/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2008
 *      Swinburne University of Technology, Melbourne, Australia.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *  1. Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS "AS IS" AND
 *  ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 *  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 *  ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
 *  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 *  DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 *  OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 *  HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 *  LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 *  OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 *  SUCH DAMAGE.
 */

/*
 * Alias_sctp forms part of the libalias kernel module to handle
 * Network Address Translation (NAT) for the SCTP protocol.
 *
 *  This software was developed by David A. Hayes and Jason But
 *
 * The design is outlined in CAIA technical report number  080618A
 * (D. Hayes and J. But, "Alias_sctp Version 0.1: SCTP NAT implementation in IPFW")
 *
 * Development is part of the CAIA SONATA project,
 * proposed by Jason But and Grenville Armitage:
 * http://caia.swin.edu.au/urp/sonata/
 *
 *
 * This project has been made possible in part by a grant from
 * the Cisco University Research Program Fund at Community
 * Foundation Silicon Valley.
 *
 */
/** @mainpage
 * Alias_sctp is part of the SONATA (http://caia.swin.edu.au/urp/sonata) project
 * to develop and release a BSD licensed implementation of a Network Address
 * Translation (NAT) module that supports the Stream Control Transmission
 * Protocol (SCTP).
 *
 * Traditional address and port number look ups are inadequate for SCTP's
 * operation due to both processing requirements and issues with multi-homing.
 * Alias_sctp integrates with FreeBSD's ipfw/libalias NAT system.
 *
 * Version 0.2 features include:
 * - Support for global multi-homing
 * - Support for ASCONF modification from Internet Draft
 *   (draft-stewart-behave-sctpnat-04, R. Stewart and M. Tuexen, "Stream control
 *   transmission protocol (SCTP) network address translation," Jul. 2008) to
 *   provide support for multi-homed privately addressed hosts
 * - Support for forwarding of T-flagged packets
 * - Generation and delivery of AbortM/ErrorM packets upon detection of NAT
 *   collisions
 * - Per-port forwarding rules
 * - Dynamically controllable logging and statistics
 * - Dynamic management of timers
 * - Dynamic control of hash-table size
 */


#ifdef _KERNEL
#include <sys/param.h>
#include <sys/gsb_crc32.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/module.h>
#include <sys/stdarg.h>
#include <sys/syslog.h>
#include <netinet/libalias/alias_sctp.h>
#include <netinet/libalias/alias.h>
#include <netinet/libalias/alias_local.h>
#include <netinet/sctp_crc32.h>
#include <machine/in_cksum.h>
#else
#include "alias_sctp.h"
#include <arpa/inet.h>
#include "alias.h"
#include "alias_local.h"
#include <machine/in_cksum.h>
#include <sys/libkern.h>
#endif //#ifdef _KERNEL

/* ----------------------------------------------------------------------
 *                          FUNCTION PROTOTYPES
 * ----------------------------------------------------------------------
 */
/* Packet Parsing Functions */
static int sctp_PktParser(struct libalias *la, int direction, struct ip *pip,
    struct sctp_nat_msg *sm, struct sctp_nat_assoc **passoc);
static int GetAsconfVtags(struct libalias *la, struct sctp_nat_msg *sm,
    uint32_t *l_vtag, uint32_t *g_vtag, int direction);
static int IsASCONFack(struct libalias *la, struct sctp_nat_msg *sm, int direction);

static void AddGlobalIPAddresses(struct sctp_nat_msg *sm, struct sctp_nat_assoc *assoc, int direction);
static int  Add_Global_Address_to_List(struct sctp_nat_assoc *assoc,  struct sctp_GlobalAddress *G_addr);
static void RmGlobalIPAddresses(struct sctp_nat_msg *sm, struct sctp_nat_assoc *assoc, int direction);
static int IsADDorDEL(struct libalias *la, struct sctp_nat_msg *sm, int direction);

/* State Machine Functions */
static int ProcessSctpMsg(struct libalias *la, int direction, \
    struct sctp_nat_msg *sm, struct sctp_nat_assoc *assoc);

static int ID_process(struct libalias *la, int direction,\
    struct sctp_nat_assoc *assoc, struct sctp_nat_msg *sm);
static int INi_process(struct libalias *la, int direction,\
    struct sctp_nat_assoc *assoc, struct sctp_nat_msg *sm);
static int INa_process(struct libalias *la, int direction,\
    struct sctp_nat_assoc *assoc, struct sctp_nat_msg *sm);
static int UP_process(struct libalias *la, int direction,\
    struct sctp_nat_assoc *assoc, struct sctp_nat_msg *sm);
static int CL_process(struct libalias *la, int direction,\
    struct sctp_nat_assoc *assoc, struct sctp_nat_msg *sm);
static void TxAbortErrorM(struct libalias *la,  struct sctp_nat_msg *sm,\
    struct sctp_nat_assoc *assoc, int sndrply, int direction);

/* Hash Table Functions */
static struct sctp_nat_assoc *
FindSctpLocal(struct libalias *la, struct in_addr l_addr, struct in_addr g_addr, uint32_t l_vtag, uint16_t l_port, uint16_t g_port);
static struct sctp_nat_assoc *
FindSctpGlobal(struct libalias *la, struct in_addr g_addr, uint32_t g_vtag, uint16_t g_port, uint16_t l_port, int *partial_match);
static struct sctp_nat_assoc *
FindSctpGlobalClash(struct libalias *la,  struct sctp_nat_assoc *Cassoc);
static struct sctp_nat_assoc *
FindSctpLocalT(struct libalias *la,  struct in_addr g_addr, uint32_t l_vtag, uint16_t g_port, uint16_t l_port);
static struct sctp_nat_assoc *
FindSctpGlobalT(struct libalias *la, struct in_addr g_addr, uint32_t g_vtag, uint16_t l_port, uint16_t g_port);

static int AddSctpAssocLocal(struct libalias *la, struct sctp_nat_assoc *assoc, struct in_addr g_addr);
static int AddSctpAssocGlobal(struct libalias *la, struct sctp_nat_assoc *assoc);
static void RmSctpAssoc(struct libalias *la, struct sctp_nat_assoc *assoc);
static void freeGlobalAddressList(struct sctp_nat_assoc *assoc);

/* Timer Queue Functions */
static void sctp_AddTimeOut(struct libalias *la, struct sctp_nat_assoc *assoc);
static void sctp_RmTimeOut(struct libalias *la, struct sctp_nat_assoc *assoc);
static void sctp_ResetTimeOut(struct libalias *la, struct sctp_nat_assoc *assoc, int newexp);
void sctp_CheckTimers(struct libalias *la);

/* Logging Functions */
static void logsctperror(char *errormsg, uint32_t vtag, int error, int direction);
static void logsctpparse(int direction, struct sctp_nat_msg *sm);
static void logsctpassoc(struct sctp_nat_assoc *assoc, char *s);
static void logTimerQ(struct libalias *la);
static void logSctpGlobal(struct libalias *la);
static void logSctpLocal(struct libalias *la);
#ifdef _KERNEL
static void SctpAliasLog(const char *format, ...);
#endif

/** @defgroup external External code changes and modifications
 *
 * Some changes have been made to files external to alias_sctp.(c|h). These
 * changes are primarily due to code needing to call static functions within
 * those files or to perform extra functionality that can only be performed
 * within these files.
 */
/** @ingroup external
 * @brief Log current statistics for the libalias instance
 *
 * This function is defined in alias_db.c, since it calls static functions in
 * this file
 *
 * Calls the higher level ShowAliasStats() in alias_db.c which logs all current
 * statistics about the libalias instance - including SCTP statistics
 *
 * @param la Pointer to the libalias instance
 */
void SctpShowAliasStats(struct libalias *la);

#ifdef _KERNEL

static MALLOC_DEFINE(M_SCTPNAT, "sctpnat", "sctp nat dbs");
/* Use kernel allocator. */
#ifdef _SYS_MALLOC_H_
#define sn_malloc(x)    malloc(x, M_SCTPNAT, M_NOWAIT|M_ZERO)
#define sn_calloc(n,x)  mallocarray((n), (x), M_SCTPNAT, M_NOWAIT|M_ZERO)
#define sn_free(x)      free(x, M_SCTPNAT)
#endif// #ifdef _SYS_MALLOC_H_

#else //#ifdef  _KERNEL
#define sn_malloc(x)    malloc(x)
#define sn_calloc(n, x) calloc(n, x)
#define sn_free(x)      free(x)

#endif //#ifdef _KERNEL

/** @defgroup packet_parser SCTP Packet Parsing
 *
 * Macros to:
 * - Return pointers to the first and next SCTP chunks within an SCTP Packet
 * - Define possible return values of the packet parsing process
 * - SCTP message types for storing in the sctp_nat_msg structure @{
 */

#define SN_SCTP_FIRSTCHUNK(sctphead)    (struct sctp_chunkhdr *)(((char *)sctphead) + sizeof(struct sctphdr))
/**< Returns a pointer to the first chunk in an SCTP packet given a pointer to the SCTP header */

#define SN_SCTP_NEXTCHUNK(chunkhead)    (struct sctp_chunkhdr *)(((char *)chunkhead) + SCTP_SIZE32(ntohs(chunkhead->chunk_length)))
/**< Returns a pointer to the next chunk in an SCTP packet given a pointer to the current chunk */

#define SN_SCTP_NEXTPARAM(param)        (struct sctp_paramhdr *)(((char *)param) + SCTP_SIZE32(ntohs(param->param_length)))
/**< Returns a pointer to the next parameter in an SCTP packet given a pointer to the current parameter */

#define SN_MIN_CHUNK_SIZE        4    /**< Smallest possible SCTP chunk size in bytes */
#define SN_MIN_PARAM_SIZE        4    /**< Smallest possible SCTP param size in bytes */
#define SN_VTAG_PARAM_SIZE      12    /**< Size of  SCTP ASCONF vtag param in bytes */
#define SN_ASCONFACK_PARAM_SIZE  8    /**< Size of  SCTP ASCONF ACK param in bytes */

/* Packet parsing return codes */
#define SN_PARSE_OK                  0    /**< Packet parsed for SCTP messages */
#define SN_PARSE_ERROR_IPSHL         1    /**< Packet parsing error - IP and SCTP common header len */
#define SN_PARSE_ERROR_AS_MALLOC     2    /**< Packet parsing error - assoc malloc */
#define SN_PARSE_ERROR_CHHL          3    /**< Packet parsing error - Chunk header len */
#define SN_PARSE_ERROR_DIR           4    /**< Packet parsing error - Direction */
#define SN_PARSE_ERROR_VTAG          5    /**< Packet parsing error - Vtag */
#define SN_PARSE_ERROR_CHUNK         6    /**< Packet parsing error - Chunk */
#define SN_PARSE_ERROR_PORT          7    /**< Packet parsing error - Port=0 */
#define SN_PARSE_ERROR_LOOKUP        8    /**< Packet parsing error - Lookup */
#define SN_PARSE_ERROR_PARTIALLOOKUP 9    /**< Packet parsing error - partial lookup only found */
#define SN_PARSE_ERROR_LOOKUP_ABORT  10   /**< Packet parsing error - Lookup - but abort packet */

/* Alias_sctp performs its processing based on a number of key messages */
#define SN_SCTP_ABORT       0x0000    /**< a packet containing an ABORT chunk */
#define SN_SCTP_INIT        0x0001    /**< a packet containing an INIT chunk */
#define SN_SCTP_INITACK     0x0002    /**< a packet containing an INIT-ACK chunk */
#define SN_SCTP_SHUTCOMP    0x0010    /**< a packet containing a SHUTDOWN-COMPLETE chunk */
#define SN_SCTP_SHUTACK     0x0020    /**< a packet containing a SHUTDOWN-ACK chunk */
#define SN_SCTP_ASCONF      0x0100    /**< a packet containing an ASCONF chunk */
#define SN_SCTP_ASCONFACK   0x0200    /**< a packet containing an ASCONF-ACK chunk */
#define SN_SCTP_OTHER       0xFFFF    /**< a packet containing a chunk that is not of interest */
/** @}
 * @defgroup state_machine SCTP NAT State Machine
 *
 * Defines the various states an association can be within the NAT @{
 */
#define SN_ID  0x0000           /**< Idle state */
#define SN_INi 0x0010           /**< Initialising, waiting for InitAck state */
#define SN_INa 0x0020           /**< Initialising, waiting for AddIpAck state */
#define SN_UP  0x0100           /**< Association in UP state */
#define SN_CL  0x1000           /**< Closing state */
#define SN_RM  0x2000           /**< Removing state */
/** @}
 * @defgroup Logging Logging Functionality
 *
 * Define various log levels and a macro to call specified log functions only if
 * the current log level (sysctl_log_level) matches the specified level @{
 */
#define SN_LOG_LOW        0
#define SN_LOG_EVENT      1
#define SN_LOG_INFO       2
#define SN_LOG_DETAIL     3
#define SN_LOG_DEBUG      4
#define SN_LOG_DEBUG_MAX  5

#define SN_LOG(level, action)   if (sysctl_log_level >= level) { action; } /**< Perform log action ONLY if the current log level meets the specified log level */
/** @}
 * @defgroup Hash Hash Table Macros and Functions
 *
 * Defines minimum/maximum/default values for the hash table size @{
 */
#define SN_MIN_HASH_SIZE        101   /**< Minimum hash table size (set to stop users choosing stupid values) */
#define SN_MAX_HASH_SIZE    1000001   /**< Maximum hash table size (NB must be less than max int) */
#define SN_DEFAULT_HASH_SIZE   2003   /**< A reasonable default size for the hash tables */

#define SN_LOCAL_TBL           0x01   /**< assoc in local table */
#define SN_GLOBAL_TBL          0x02   /**< assoc in global table */
#define SN_BOTH_TBL            0x03   /**< assoc in both tables */
#define SN_WAIT_TOLOCAL        0x10   /**< assoc waiting for TOLOCAL asconf ACK*/
#define SN_WAIT_TOGLOBAL       0x20   /**< assoc waiting for TOLOCAL asconf ACK*/
#define SN_NULL_TBL            0x00   /**< assoc in No table */
#define SN_MAX_GLOBAL_ADDRESSES 100   /**< absolute maximum global address count*/

#define SN_ADD_OK                 0   /**< Association added to the table */
#define SN_ADD_CLASH              1   /**< Clash when trying to add the assoc. info to the table */

#define SN_TABLE_HASH(vtag, port, size) (((u_int) vtag + (u_int) port) % (u_int) size) /**< Calculate the hash table lookup position */
/** @}
 * @defgroup Timer Timer Queue Macros and Functions
 *
 * Timer macros set minimum/maximum timeout values and calculate timer expiry
 * times for the provided libalias instance @{
 */
#define SN_MIN_TIMER 1
#define SN_MAX_TIMER 600
#define SN_TIMER_QUEUE_SIZE SN_MAX_TIMER+2

#define SN_I_T(la) (LibAliasTime + sysctl_init_timer)       /**< INIT State expiration time in seconds */
#define SN_U_T(la) (LibAliasTime + sysctl_up_timer)         /**< UP State expiration time in seconds */
#define SN_C_T(la) (LibAliasTime + sysctl_shutdown_timer)   /**< CL State expiration time in seconds */
#define SN_X_T(la) (LibAliasTime + sysctl_holddown_timer)   /**< Wait after a shutdown complete in seconds */
/** @}
 * @defgroup sysctl SysCtl Variable and callback function declarations
 *
 * Sysctl variables to modify NAT functionality in real-time along with associated functions
 * to manage modifications to the sysctl variables @{
 */

/* Callbacks */
int sysctl_chg_loglevel(SYSCTL_HANDLER_ARGS);
int sysctl_chg_timer(SYSCTL_HANDLER_ARGS);
int sysctl_chg_hashtable_size(SYSCTL_HANDLER_ARGS);
int sysctl_chg_error_on_ootb(SYSCTL_HANDLER_ARGS);
int sysctl_chg_accept_global_ootb_addip(SYSCTL_HANDLER_ARGS);
int sysctl_chg_initialising_chunk_proc_limit(SYSCTL_HANDLER_ARGS);
int sysctl_chg_chunk_proc_limit(SYSCTL_HANDLER_ARGS);
int sysctl_chg_param_proc_limit(SYSCTL_HANDLER_ARGS);
int sysctl_chg_track_global_addresses(SYSCTL_HANDLER_ARGS);

/* Sysctl variables */
/** @brief net.inet.ip.alias.sctp.log_level */
static u_int sysctl_log_level = 0; /**< Stores the current level of logging */
/** @brief net.inet.ip.alias.sctp.init_timer */
static u_int sysctl_init_timer = 15; /**< Seconds to hold an association in the table waiting for an INIT-ACK or AddIP-ACK */
/** @brief net.inet.ip.alias.sctp.up_timer */
static u_int sysctl_up_timer = 300; /**< Seconds to hold an association in the table while no packets are transmitted */
/** @brief net.inet.ip.alias.sctp.shutdown_timer */
static u_int sysctl_shutdown_timer = 15; /**< Seconds to hold an association in the table waiting for a SHUTDOWN-COMPLETE */
/** @brief net.inet.ip.alias.sctp.holddown_timer */
static u_int sysctl_holddown_timer = 0; /**< Seconds to hold an association in the table after it has been shutdown (to allow for lost SHUTDOWN-COMPLETEs) */
/** @brief net.inet.ip.alias.sctp.hashtable_size */
static u_int sysctl_hashtable_size = SN_DEFAULT_HASH_SIZE; /**< Sets the hash table size for any NEW NAT instances (existing instances retain their existing Hash Table */
/** @brief net.inet.ip.alias.sctp.error_on_ootb */
static u_int sysctl_error_on_ootb = 1; /**< NAT response  to receipt of OOTB packet
                                          (0 - No response, 1 - NAT will send ErrorM only to local side,
                                          2 -  NAT will send local ErrorM and global ErrorM if there was a partial association match
                                          3 - NAT will send ErrorM to both local and global) */
/** @brief net.inet.ip.alias.sctp.accept_global_ootb_addip */
static u_int sysctl_accept_global_ootb_addip = 0; /**<NAT responset to receipt of global OOTB AddIP (0 - No response, 1 - NAT will accept OOTB global AddIP messages for processing (Security risk)) */
/** @brief net.inet.ip.alias.sctp.initialising_chunk_proc_limit */
static u_int sysctl_initialising_chunk_proc_limit = 2; /**< A limit on the number of chunks that should be searched if there is no matching association (DoS prevention) */
/** @brief net.inet.ip.alias.sctp.param_proc_limit */
static u_int sysctl_chunk_proc_limit = 5; /**< A limit on the number of chunks that should be searched (DoS prevention) */
/** @brief net.inet.ip.alias.sctp.param_proc_limit */
static u_int sysctl_param_proc_limit = 25; /**< A limit on the number of parameters (in chunks) that should be searched (DoS prevention) */
/** @brief net.inet.ip.alias.sctp.track_global_addresses */
static u_int sysctl_track_global_addresses = 0; /**< Configures the global address tracking option within the NAT (0 - Global tracking is disabled, > 0 - enables tracking but limits the number of global IP addresses to this value)
                                                   If set to >=1 the NAT will track that many global IP addresses. This may reduce look up table conflicts, but increases processing */

#define SN_NO_ERROR_ON_OOTB              0 /**< Send no errorM on out of the blue packets */
#define SN_LOCAL_ERROR_ON_OOTB           1 /**< Send only local errorM on out of the blue packets */
#define SN_LOCALandPARTIAL_ERROR_ON_OOTB 2 /**< Send local errorM and global errorM for out of the blue packets only if partial match found */
#define SN_ERROR_ON_OOTB                 3 /**< Send errorM on out of the blue packets */

#ifdef SYSCTL_NODE

SYSCTL_DECL(_net_inet);
SYSCTL_DECL(_net_inet_ip);
SYSCTL_DECL(_net_inet_ip_alias);

static SYSCTL_NODE(_net_inet_ip_alias, OID_AUTO, sctp,
    CTLFLAG_RW | CTLFLAG_MPSAFE, NULL,
    "SCTP NAT");
SYSCTL_PROC(_net_inet_ip_alias_sctp, OID_AUTO, log_level,
    CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
    &sysctl_log_level, 0, sysctl_chg_loglevel, "IU",
    "Level of detail (0 - default, 1 - event, 2 - info, 3 - detail, 4 - debug, 5 - max debug)");
SYSCTL_PROC(_net_inet_ip_alias_sctp, OID_AUTO, init_timer,
    CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
    &sysctl_init_timer, 0, sysctl_chg_timer, "IU",
    "Timeout value (s) while waiting for (INIT-ACK|AddIP-ACK)");
SYSCTL_PROC(_net_inet_ip_alias_sctp, OID_AUTO, up_timer,
    CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
    &sysctl_up_timer, 0, sysctl_chg_timer, "IU",
    "Timeout value (s) to keep an association up with no traffic");
SYSCTL_PROC(_net_inet_ip_alias_sctp, OID_AUTO, shutdown_timer,
    CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
    &sysctl_shutdown_timer, 0, sysctl_chg_timer, "IU",
    "Timeout value (s) while waiting for SHUTDOWN-COMPLETE");
SYSCTL_PROC(_net_inet_ip_alias_sctp, OID_AUTO, holddown_timer,
    CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
    &sysctl_holddown_timer, 0, sysctl_chg_timer, "IU",
    "Hold association in table for this many seconds after receiving a SHUTDOWN-COMPLETE");
SYSCTL_PROC(_net_inet_ip_alias_sctp, OID_AUTO, hashtable_size,
    CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
    &sysctl_hashtable_size, 0, sysctl_chg_hashtable_size, "IU",
    "Size of hash tables used for NAT lookups (100 < prime_number > 1000001)");
SYSCTL_PROC(_net_inet_ip_alias_sctp, OID_AUTO, error_on_ootb,
    CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
    &sysctl_error_on_ootb, 0, sysctl_chg_error_on_ootb, "IU",
    "ErrorM sent on receipt of ootb packet:\n\t0 - none,\n"
    "\t1 - to local only,\n"
    "\t2 - to local and global if a partial association match,\n"
    "\t3 - to local and global (DoS risk)");
SYSCTL_PROC(_net_inet_ip_alias_sctp, OID_AUTO, accept_global_ootb_addip,
    CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
    &sysctl_accept_global_ootb_addip, 0, sysctl_chg_accept_global_ootb_addip, "IU",
    "NAT response to receipt of global OOTB AddIP:\n"
    "\t0 - No response,\n"
    "\t1 - NAT will accept OOTB global AddIP messages for processing (Security risk)");
SYSCTL_PROC(_net_inet_ip_alias_sctp, OID_AUTO, initialising_chunk_proc_limit,
    CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
    &sysctl_initialising_chunk_proc_limit, 0,
    sysctl_chg_initialising_chunk_proc_limit, "IU",
    "Number of chunks that should be processed if there is no current "
    "association found:\n\t > 0 (A high value is a DoS risk)");
SYSCTL_PROC(_net_inet_ip_alias_sctp, OID_AUTO, chunk_proc_limit,
    CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
    &sysctl_chunk_proc_limit, 0, sysctl_chg_chunk_proc_limit, "IU",
    "Number of chunks that should be processed to find key chunk:\n"
    "\t>= initialising_chunk_proc_limit (A high value is a DoS risk)");
SYSCTL_PROC(_net_inet_ip_alias_sctp, OID_AUTO, param_proc_limit,
    CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
    &sysctl_param_proc_limit, 0, sysctl_chg_param_proc_limit, "IU",
    "Number of parameters (in a chunk) that should be processed to find key "
    "parameters:\n\t> 1 (A high value is a DoS risk)");
SYSCTL_PROC(_net_inet_ip_alias_sctp, OID_AUTO, track_global_addresses,
    CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
    &sysctl_track_global_addresses, 0, sysctl_chg_track_global_addresses, "IU",
    "Configures the global address tracking option within the NAT:\n"
    "\t0 - Global tracking is disabled,\n"
    "\t> 0 - enables tracking but limits the number of global IP addresses to this value");

#endif /* SYSCTL_NODE */
/** @}
 * @ingroup sysctl
 * @brief sysctl callback for changing net.inet.ip.fw.sctp.log_level
 *
 * Updates the variable sysctl_log_level to the provided value and ensures
 * it is in the valid range (SN_LOG_LOW -> SN_LOG_DEBUG)
 */
int sysctl_chg_loglevel(SYSCTL_HANDLER_ARGS)
{
        u_int level = *(u_int *)arg1;
        int error;

        error = sysctl_handle_int(oidp, &level, 0, req);
        if (error)
                return (error);

        level = (level > SN_LOG_DEBUG_MAX) ? (SN_LOG_DEBUG_MAX) : (level);
        level = (level < SN_LOG_LOW) ? (SN_LOG_LOW) : (level);
        sysctl_log_level = level;
        return (0);
}

/** @ingroup sysctl
 * @brief sysctl callback for changing net.inet.ip.fw.sctp.(init_timer|up_timer|shutdown_timer)
 *
 * Updates the timer-based sysctl variables. The new values are sanity-checked
 * to make sure that they are within the range SN_MIN_TIMER-SN_MAX_TIMER. The
 * holddown timer is allowed to be 0
 */
int sysctl_chg_timer(SYSCTL_HANDLER_ARGS)
{
        u_int timer = *(u_int *)arg1;
        int error;

        error = sysctl_handle_int(oidp, &timer, 0, req);
        if (error)
                return (error);

        timer = (timer > SN_MAX_TIMER) ? (SN_MAX_TIMER) : (timer);

        if (((u_int *)arg1) != &sysctl_holddown_timer) {
                timer = (timer < SN_MIN_TIMER) ? (SN_MIN_TIMER) : (timer);
        }

        *(u_int *)arg1 = timer;

        return (0);
}

/** @ingroup sysctl
 * @brief sysctl callback for changing net.inet.ip.alias.sctp.hashtable_size
 *
 * Updates the hashtable_size sysctl variable. The new value should be a prime
 * number.  We sanity check to ensure that the size is within the range
 * SN_MIN_HASH_SIZE-SN_MAX_HASH_SIZE. We then check the provided number to see
 * if it is prime. We approximate by checking that (2,3,5,7,11) are not factors,
 * incrementing the user provided value until we find a suitable number.
 */
int sysctl_chg_hashtable_size(SYSCTL_HANDLER_ARGS)
{
        u_int size = *(u_int *)arg1;
        int error;

        error = sysctl_handle_int(oidp, &size, 0, req);
        if (error)
                return (error);

        size = (size < SN_MIN_HASH_SIZE) ? (SN_MIN_HASH_SIZE) : ((size > SN_MAX_HASH_SIZE) ? (SN_MAX_HASH_SIZE) : (size));

        size |= 0x00000001; /* make odd */

        for (;(((size % 3) == 0) || ((size % 5) == 0) || ((size % 7) == 0) || ((size % 11) == 0)); size+=2);
        sysctl_hashtable_size = size;

        return (0);
}

/** @ingroup sysctl
 * @brief sysctl callback for changing net.inet.ip.alias.sctp.error_on_ootb
 *
 * Updates the error_on_clash sysctl variable.
 * If set to 0, no ErrorM will be sent if there is a look up table clash
 * If set to 1, an ErrorM is sent only to the local side
 * If set to 2, an ErrorM is sent to the local side and global side if there is
 *                                                  a partial association match
 * If set to 3, an ErrorM is sent to both local and global sides (DoS) risk.
 */
int sysctl_chg_error_on_ootb(SYSCTL_HANDLER_ARGS)
{
        u_int flag = *(u_int *)arg1;
        int error;

        error = sysctl_handle_int(oidp, &flag, 0, req);
        if (error)
                return (error);

        sysctl_error_on_ootb = (flag > SN_ERROR_ON_OOTB) ? SN_ERROR_ON_OOTB: flag;

        return (0);
}

/** @ingroup sysctl
 * @brief sysctl callback for changing net.inet.ip.alias.sctp.accept_global_ootb_addip
 *
 * If set to 1 the NAT will accept ootb global addip messages for processing (Security risk)
 * Default is 0, only responding to local ootb AddIP messages
 */
int sysctl_chg_accept_global_ootb_addip(SYSCTL_HANDLER_ARGS)
{
        u_int flag = *(u_int *)arg1;
        int error;

        error = sysctl_handle_int(oidp, &flag, 0, req);
        if (error)
                return (error);

        sysctl_accept_global_ootb_addip = (flag == 1) ? 1: 0;

        return (0);
}

/** @ingroup sysctl
 * @brief sysctl callback for changing net.inet.ip.alias.sctp.initialising_chunk_proc_limit
 *
 * Updates the initialising_chunk_proc_limit sysctl variable.  Number of chunks
 * that should be processed if there is no current association found: > 0 (A
 * high value is a DoS risk)
 */
int sysctl_chg_initialising_chunk_proc_limit(SYSCTL_HANDLER_ARGS)
{
        u_int proclimit = *(u_int *)arg1;
        int error;

        error = sysctl_handle_int(oidp, &proclimit, 0, req);
        if (error)
                return (error);

        sysctl_initialising_chunk_proc_limit = (proclimit < 1) ? 1: proclimit;
        sysctl_chunk_proc_limit =
                (sysctl_chunk_proc_limit < sysctl_initialising_chunk_proc_limit) ? sysctl_initialising_chunk_proc_limit : sysctl_chunk_proc_limit;

        return (0);
}

/** @ingroup sysctl
 * @brief sysctl callback for changing net.inet.ip.alias.sctp.chunk_proc_limit
 *
 * Updates the chunk_proc_limit sysctl variable.
 * Number of chunks that should be processed to find key chunk:
 *  >= initialising_chunk_proc_limit (A high value is a DoS risk)
 */
int sysctl_chg_chunk_proc_limit(SYSCTL_HANDLER_ARGS)
{
        u_int proclimit = *(u_int *)arg1;
        int error;

        error = sysctl_handle_int(oidp, &proclimit, 0, req);
        if (error)
                return (error);

        sysctl_chunk_proc_limit =
                (proclimit < sysctl_initialising_chunk_proc_limit) ? sysctl_initialising_chunk_proc_limit : proclimit;

        return (0);
}

/** @ingroup sysctl
 * @brief sysctl callback for changing net.inet.ip.alias.sctp.param_proc_limit
 *
 * Updates the param_proc_limit sysctl variable.
 * Number of parameters that should be processed to find key parameters:
 *  > 1 (A high value is a DoS risk)
 */
int sysctl_chg_param_proc_limit(SYSCTL_HANDLER_ARGS)
{
        u_int proclimit = *(u_int *)arg1;
        int error;

        error = sysctl_handle_int(oidp, &proclimit, 0, req);
        if (error)
                return (error);

        sysctl_param_proc_limit =
                (proclimit < 2) ? 2 : proclimit;

        return (0);
}

/** @ingroup sysctl
 * @brief sysctl callback for changing net.inet.ip.alias.sctp.track_global_addresses
 *
 *Configures the global address tracking option within the NAT (0 - Global
 *tracking is disabled, > 0 - enables tracking but limits the number of global
 *IP addresses to this value)
 */
int sysctl_chg_track_global_addresses(SYSCTL_HANDLER_ARGS)
{
        u_int num_to_track = *(u_int *)arg1;
        int error;

        error = sysctl_handle_int(oidp, &num_to_track, 0, req);
        if (error)
                return (error);

        sysctl_track_global_addresses = (num_to_track > SN_MAX_GLOBAL_ADDRESSES) ? SN_MAX_GLOBAL_ADDRESSES : num_to_track;

        return (0);
}

/* ----------------------------------------------------------------------
 *                            CODE BEGINS HERE
 * ----------------------------------------------------------------------
 */
/**
 * @brief Initialises the SCTP NAT Implementation
 *
 * Creates the look-up tables and the timer queue and initialises all state
 * variables
 *
 * @param la Pointer to the relevant libalias instance
 */
void
AliasSctpInit(struct libalias *la)
{
        /* Initialise association tables*/
        int i;
        la->sctpNatTableSize = sysctl_hashtable_size;
        SN_LOG(SN_LOG_EVENT,
            SctpAliasLog("Initialising SCTP NAT Instance (hash_table_size:%d)\n", la->sctpNatTableSize));
        la->sctpTableLocal = sn_calloc(la->sctpNatTableSize, sizeof(struct sctpNatTableL));
        la->sctpTableGlobal = sn_calloc(la->sctpNatTableSize, sizeof(struct sctpNatTableG));
        la->sctpNatTimer.TimerQ = sn_calloc(SN_TIMER_QUEUE_SIZE, sizeof(struct sctpTimerQ));
        /* Initialise hash table */
        for (i = 0; i < la->sctpNatTableSize; i++) {
                LIST_INIT(&la->sctpTableLocal[i]);
                LIST_INIT(&la->sctpTableGlobal[i]);
        }

        /* Initialise circular timer Q*/
        for (i = 0; i < SN_TIMER_QUEUE_SIZE; i++)
                LIST_INIT(&la->sctpNatTimer.TimerQ[i]);
#ifdef _KERNEL
        la->sctpNatTimer.loc_time=time_uptime; /* LibAliasTime is not set yet */
#else
        la->sctpNatTimer.loc_time=LibAliasTime;
#endif
        la->sctpNatTimer.cur_loc = 0;
        la->sctpLinkCount = 0;
}

/**
 * @brief Cleans-up the SCTP NAT Implementation prior to unloading
 *
 * Removes all entries from the timer queue, freeing associations as it goes.
 * We then free memory allocated to the look-up tables and the time queue
 *
 * NOTE: We do not need to traverse the look-up tables as each association
 *       will always have an entry in the timer queue, freeing this memory
 *       once will free all memory allocated to entries in the look-up tables
 *
 * @param la Pointer to the relevant libalias instance
 */
void
AliasSctpTerm(struct libalias *la)
{
        struct sctp_nat_assoc *assoc1, *assoc2;
        int                   i;

        LIBALIAS_LOCK_ASSERT(la);
        SN_LOG(SN_LOG_EVENT,
            SctpAliasLog("Removing SCTP NAT Instance\n"));
        for (i = 0; i < SN_TIMER_QUEUE_SIZE; i++) {
                assoc1 = LIST_FIRST(&la->sctpNatTimer.TimerQ[i]);
                while (assoc1 != NULL) {
                        freeGlobalAddressList(assoc1);
                        assoc2 = LIST_NEXT(assoc1, timer_Q);
                        sn_free(assoc1);
                        assoc1 = assoc2;
                }
        }

        sn_free(la->sctpTableLocal);
        sn_free(la->sctpTableGlobal);
        sn_free(la->sctpNatTimer.TimerQ);
}

/**
 * @brief Handles SCTP packets passed from libalias
 *
 * This function needs to actually NAT/drop packets and possibly create and
 * send AbortM or ErrorM packets in response. The process involves:
 * - Validating the direction parameter passed by the caller
 * - Checking and handling any expired timers for the NAT
 * - Calling sctp_PktParser() to parse the packet
 * - Call ProcessSctpMsg() to decide the appropriate outcome and to update
 *   the NAT tables
 * - Based on the return code either:
 *   - NAT the packet
 *   - Construct and send an ErrorM|AbortM packet
 *   - Mark the association for removal from the tables
 * - Potentially remove the association from all lookup tables
 * - Return the appropriate result to libalias
 *
 * @param la Pointer to the relevant libalias instance
 * @param pip Pointer to IP packet to process
 * @param direction SN_TO_LOCAL | SN_TO_GLOBAL
 *
 * @return  PKT_ALIAS_OK | PKT_ALIAS_IGNORE | PKT_ALIAS_ERROR
 */
int
SctpAlias(struct libalias *la, struct ip *pip, int direction)
{
        int rtnval;
        struct sctp_nat_msg msg;
        struct sctp_nat_assoc *assoc = NULL;

        if ((direction != SN_TO_LOCAL) && (direction != SN_TO_GLOBAL)) {
                SctpAliasLog("ERROR: Invalid direction\n");
                return (PKT_ALIAS_ERROR);
        }

        sctp_CheckTimers(la); /* Check timers */

        /* Parse the packet */
        rtnval = sctp_PktParser(la, direction, pip, &msg, &assoc); //using *char (change to mbuf when get code from paolo)
        switch (rtnval) {
        case SN_PARSE_OK:
                break;
        case SN_PARSE_ERROR_CHHL:
                /*
                 * Not an error, if there is a chunk length parsing error,
                 * this is a fragmented packet, and we have a valid assoc.
                 */
                if ((assoc != NULL) && (ntohs(pip->ip_off) & IP_MF)) {
                        rtnval = SN_PARSE_OK;
                        break;
                }
                SN_LOG(SN_LOG_EVENT,
                    logsctperror("SN_PARSE_ERROR", msg.sctp_hdr->v_tag, rtnval, direction));
                return (PKT_ALIAS_ERROR);
        case SN_PARSE_ERROR_PARTIALLOOKUP:
                if (sysctl_error_on_ootb > SN_LOCALandPARTIAL_ERROR_ON_OOTB) {
                        SN_LOG(SN_LOG_EVENT,
                            logsctperror("SN_PARSE_ERROR", msg.sctp_hdr->v_tag, rtnval, direction));
                        return (PKT_ALIAS_ERROR);
                }
        case SN_PARSE_ERROR_LOOKUP:
                if (sysctl_error_on_ootb == SN_ERROR_ON_OOTB ||
                    (sysctl_error_on_ootb == SN_LOCALandPARTIAL_ERROR_ON_OOTB && direction == SN_TO_LOCAL) ||
                    (sysctl_error_on_ootb == SN_LOCAL_ERROR_ON_OOTB && direction == SN_TO_GLOBAL)) {
                        TxAbortErrorM(la, &msg, assoc, SN_REFLECT_ERROR, direction); /*NB assoc=NULL */
                        return (PKT_ALIAS_RESPOND);
                }
        default:
                SN_LOG(SN_LOG_EVENT,
                    logsctperror("SN_PARSE_ERROR", msg.sctp_hdr->v_tag, rtnval, direction));
                return (PKT_ALIAS_ERROR);
        }

        SN_LOG(SN_LOG_DETAIL,
            logsctpassoc(assoc, "*");
            logsctpparse(direction, &msg);
        );

        /* Process the SCTP message */
        rtnval = ProcessSctpMsg(la, direction, &msg, assoc);

        SN_LOG(SN_LOG_DEBUG_MAX,
            logsctpassoc(assoc, "-");
            logSctpLocal(la);
            logSctpGlobal(la);
        );
        SN_LOG(SN_LOG_DEBUG, logTimerQ(la));

        switch (rtnval) {
        case SN_NAT_PKT:
                switch (direction) {
                case SN_TO_LOCAL:
                        DifferentialChecksum(&(msg.ip_hdr->ip_sum),
                            &(assoc->l_addr), &(msg.ip_hdr->ip_dst), 2);
                        msg.ip_hdr->ip_dst = assoc->l_addr; /* change dst address to local address*/
                        break;
                case SN_TO_GLOBAL:
                        DifferentialChecksum(&(msg.ip_hdr->ip_sum),
                            &(assoc->a_addr),  &(msg.ip_hdr->ip_src), 2);
                        msg.ip_hdr->ip_src = assoc->a_addr; /* change src to alias addr*/
                        break;
                default:
                        rtnval = SN_DROP_PKT; /* shouldn't get here, but if it does drop packet */
                        SN_LOG(SN_LOG_LOW, logsctperror("ERROR: Invalid direction", msg.sctp_hdr->v_tag, rtnval, direction));
                        break;
                }
                break;
        case SN_DROP_PKT:
                SN_LOG(SN_LOG_DETAIL, logsctperror("SN_DROP_PKT", msg.sctp_hdr->v_tag, rtnval, direction));
                break;
        case SN_REPLY_ABORT:
        case SN_REPLY_ERROR:
        case SN_SEND_ABORT:
                TxAbortErrorM(la, &msg, assoc, rtnval, direction);
                break;
        default:
                // big error, remove association and go to idle and write log messages
                SN_LOG(SN_LOG_LOW, logsctperror("SN_PROCESSING_ERROR", msg.sctp_hdr->v_tag, rtnval, direction));
                assoc->state = SN_RM;/* Mark for removal*/
                break;
        }

        /* Remove association if tagged for removal */
        if (assoc->state == SN_RM) {
                if (assoc->TableRegister) {
                        sctp_RmTimeOut(la, assoc);
                        RmSctpAssoc(la, assoc);
                }
                LIBALIAS_LOCK_ASSERT(la);
                freeGlobalAddressList(assoc);
                sn_free(assoc);
        }
        switch (rtnval) {
        case SN_NAT_PKT:
                return (PKT_ALIAS_OK);
        case SN_SEND_ABORT:
                return (PKT_ALIAS_OK);
        case SN_REPLY_ABORT:
        case SN_REPLY_ERROR:
        case SN_REFLECT_ERROR:
                return (PKT_ALIAS_RESPOND);
        case SN_DROP_PKT:
        default:
                return (PKT_ALIAS_ERROR);
        }
}

/**
 * @brief Send an AbortM or ErrorM
 *
 * We construct the new SCTP packet to send in place of the existing packet we
 * have been asked to NAT. This function can only be called if the original
 * packet was successfully parsed as a valid SCTP packet.
 *
 * An AbortM (without cause) packet is the smallest SCTP packet available and as
 * such there is always space in the existing packet buffer to fit the AbortM
 * packet. An ErrorM packet is 4 bytes longer than the (the error cause is not
 * optional). An ErrorM is sent in response to an AddIP when the Vtag/address
 * combination, if added, will produce a conflict in the association look up
 * tables. It may also be used for an unexpected packet - a packet with no
 * matching association in the NAT table and we are requesting an AddIP so we
 * can add it.  The smallest valid SCTP packet while the association is in an
 * up-state is a Heartbeat packet, which is big enough to be transformed to an
 * ErrorM.
 *
 * We create a temporary character array to store the packet as we are constructing
 * it. We then populate the array with appropriate values based on:
 * - Packet type (AbortM | ErrorM)
 * - Initial packet direction (SN_TO_LOCAL | SN_TO_GLOBAL)
 * - NAT response (Send packet | Reply packet)
 *
 * Once complete, we copy the contents of the temporary packet over the original
 * SCTP packet we were asked to NAT
 *
 * @param la Pointer to the relevant libalias instance
 * @param sm Pointer to sctp message information
 * @param assoc Pointer to current association details
 * @param sndrply SN_SEND_ABORT | SN_REPLY_ABORT | SN_REPLY_ERROR
 * @param direction SN_TO_LOCAL | SN_TO_GLOBAL
 */
static uint32_t
local_sctp_finalize_crc32(uint32_t crc32c)
{
        /* This routine is duplicated from SCTP
         * we need to do that since it MAY be that SCTP
         * is NOT compiled into the kernel. The CRC32C routines
         * however are always available in libkern.
         */
        uint32_t result;
#if BYTE_ORDER == BIG_ENDIAN
        uint8_t byte0, byte1, byte2, byte3;

#endif
        /* Complement the result */
        result = ~crc32c;
#if BYTE_ORDER == BIG_ENDIAN
        /*
         * For BIG-ENDIAN.. aka Motorola byte order the result is in
         * little-endian form. So we must manually swap the bytes. Then we
         * can call htonl() which does nothing...
         */
        byte0 = result & 0x000000ff;
        byte1 = (result >> 8) & 0x000000ff;
        byte2 = (result >> 16) & 0x000000ff;
        byte3 = (result >> 24) & 0x000000ff;
        crc32c = ((byte0 << 24) | (byte1 << 16) | (byte2 << 8) | byte3);
#else
        /*
         * For INTEL platforms the result comes out in network order. No
         * htonl is required or the swap above. So we optimize out both the
         * htonl and the manual swap above.
         */
        crc32c = result;
#endif
        return (crc32c);
}

static void
TxAbortErrorM(struct libalias *la, struct sctp_nat_msg *sm, struct sctp_nat_assoc *assoc, int sndrply, int direction)
{
        int sctp_size = sizeof(struct sctphdr) + sizeof(struct sctp_chunkhdr) + sizeof(struct sctp_error_cause);
        int ip_size = sizeof(struct ip) + sctp_size;
        int include_error_cause = 1;
        char tmp_ip[ip_size];
        char addrbuf[INET_ADDRSTRLEN];

        if (ntohs(sm->ip_hdr->ip_len) < ip_size) { /* short packet, cannot send error cause */
                include_error_cause = 0;
                ip_size = ip_size -  sizeof(struct sctp_error_cause);
                sctp_size = sctp_size -  sizeof(struct sctp_error_cause);
        }
        /* Assign header pointers packet */
        struct ip* ip = (struct ip *) tmp_ip;
        struct sctphdr* sctp_hdr = (struct sctphdr *) ((char *) ip + sizeof(*ip));
        struct sctp_chunkhdr* chunk_hdr = (struct sctp_chunkhdr *) ((char *) sctp_hdr + sizeof(*sctp_hdr));
        struct sctp_error_cause* error_cause = (struct sctp_error_cause *) ((char *) chunk_hdr + sizeof(*chunk_hdr));

        /* construct ip header */
        ip->ip_v = sm->ip_hdr->ip_v;
        ip->ip_hl = 5; /* 5*32 bit words */
        ip->ip_tos = 0;
        ip->ip_len = htons(ip_size);
        ip->ip_id = sm->ip_hdr->ip_id;
        ip->ip_off = 0;
        ip->ip_ttl = 255;
        ip->ip_p = IPPROTO_SCTP;
        /*
          The definitions below should be removed when they make it into the SCTP stack
        */
#define SCTP_MIDDLEBOX_FLAG 0x02
#define SCTP_NAT_TABLE_COLLISION 0x00b0
#define SCTP_MISSING_NAT 0x00b1
        chunk_hdr->chunk_type = (sndrply & SN_TX_ABORT) ? SCTP_ABORT_ASSOCIATION : SCTP_OPERATION_ERROR;
        chunk_hdr->chunk_flags = SCTP_MIDDLEBOX_FLAG;
        if (include_error_cause) {
                error_cause->code = htons((sndrply & SN_REFLECT_ERROR) ? SCTP_MISSING_NAT : SCTP_NAT_TABLE_COLLISION);
                error_cause->length = htons(sizeof(struct sctp_error_cause));
                chunk_hdr->chunk_length = htons(sizeof(*chunk_hdr) + sizeof(struct sctp_error_cause));
        } else {
                chunk_hdr->chunk_length = htons(sizeof(*chunk_hdr));
        }

        /* set specific values */
        switch (sndrply) {
        case SN_REFLECT_ERROR:
                chunk_hdr->chunk_flags |= SCTP_HAD_NO_TCB; /* set Tbit */
                sctp_hdr->v_tag = sm->sctp_hdr->v_tag;
                break;
        case SN_REPLY_ERROR:
                sctp_hdr->v_tag = (direction == SN_TO_LOCAL) ? assoc->g_vtag : assoc->l_vtag ;
                break;
        case SN_SEND_ABORT:
                sctp_hdr->v_tag = sm->sctp_hdr->v_tag;
                break;
        case SN_REPLY_ABORT:
                sctp_hdr->v_tag = sm->sctpchnk.Init->initiate_tag;
                break;
        }

        /* Set send/reply values */
        if (sndrply == SN_SEND_ABORT) { /*pass through NAT */
                ip->ip_src = (direction == SN_TO_LOCAL) ? sm->ip_hdr->ip_src : assoc->a_addr;
                ip->ip_dst = (direction == SN_TO_LOCAL) ? assoc->l_addr : sm->ip_hdr->ip_dst;
                sctp_hdr->src_port = sm->sctp_hdr->src_port;
                sctp_hdr->dest_port = sm->sctp_hdr->dest_port;
        } else { /* reply and reflect */
                ip->ip_src = sm->ip_hdr->ip_dst;
                ip->ip_dst = sm->ip_hdr->ip_src;
                sctp_hdr->src_port = sm->sctp_hdr->dest_port;
                sctp_hdr->dest_port = sm->sctp_hdr->src_port;
        }

        /* Calculate IP header checksum */
        ip->ip_sum = in_cksum_hdr(ip);

        /* calculate SCTP header CRC32 */
        sctp_hdr->checksum = 0;
        sctp_hdr->checksum = local_sctp_finalize_crc32(calculate_crc32c(0xffffffff, (unsigned char *) sctp_hdr, sctp_size));

        memcpy(sm->ip_hdr, ip, ip_size);

        SN_LOG(SN_LOG_EVENT,SctpAliasLog("%s %s 0x%x (->%s:%u vtag=0x%x crc=0x%x)\n",
            ((sndrply == SN_SEND_ABORT) ? "Sending" : "Replying"),
            ((sndrply & SN_TX_ERROR) ? "ErrorM" : "AbortM"),
            (include_error_cause ? ntohs(error_cause->code) : 0),
            inet_ntoa_r(ip->ip_dst, INET_NTOA_BUF(addrbuf)),
            ntohs(sctp_hdr->dest_port),
            ntohl(sctp_hdr->v_tag), ntohl(sctp_hdr->checksum)));
}

/* ----------------------------------------------------------------------
 *                           PACKET PARSER CODE
 * ----------------------------------------------------------------------
 */
/** @addtogroup packet_parser
 *
 * These functions parse the SCTP packet and fill a sctp_nat_msg structure
 * with the parsed contents.
 */
/** @ingroup packet_parser
 * @brief Parses SCTP packets for the key SCTP chunk that will be processed
 *
 * This module parses SCTP packets for the key SCTP chunk that will be processed
 * The module completes the sctp_nat_msg structure and either retrieves the
 * relevant (existing) stored association from the Hash Tables or creates a new
 * association entity with state SN_ID
 *
 * @param la Pointer to the relevant libalias instance
 * @param direction SN_TO_LOCAL | SN_TO_GLOBAL
 * @param pip
 * @param sm Pointer to sctp message information
 * @param passoc Pointer to the association this SCTP Message belongs to
 *
 * @return SN_PARSE_OK | SN_PARSE_ERROR_*
 */
static int
sctp_PktParser(struct libalias *la, int direction, struct ip *pip,
    struct sctp_nat_msg *sm, struct sctp_nat_assoc **passoc)
//sctp_PktParser(int direction, struct mbuf *ipak, int ip_hdr_len,struct sctp_nat_msg *sm, struct sctp_nat_assoc *assoc)
{
        struct sctphdr *sctp_hdr;
        struct sctp_chunkhdr *chunk_hdr;
        struct sctp_paramhdr *param_hdr;
        struct in_addr ipv4addr;
        int bytes_left; /* bytes left in ip packet */
        int chunk_length;
        int chunk_count;
        int partial_match = 0;
        //  mbuf *mp;
        //  int mlen;

        //  mlen = SCTP_HEADER_LEN(i_pak);
        //  mp = SCTP_HEADER_TO_CHAIN(i_pak); /* does nothing in bsd since header and chain not separate */

        /*
         * Note, that if the VTag is zero, it must be an INIT
         * Also, I am only interested in the content of INIT and ADDIP chunks
         */

        sm->msg = SN_SCTP_OTHER;/* Initialise to largest value*/
        sm->chunk_length = 0; /* only care about length for key chunks */
        // no mbuf stuff from Paolo yet so ...
        sm->ip_hdr = pip;
        /* remove ip header length from the bytes_left */
        bytes_left = ntohs(pip->ip_len) - (pip->ip_hl << 2);

        /* Check SCTP header length and move to first chunk */
        if (bytes_left < sizeof(struct sctphdr)) {
                sm->sctp_hdr = NULL;
                return (SN_PARSE_ERROR_IPSHL); /* packet not long enough*/
        }

        sm->sctp_hdr = sctp_hdr = (struct sctphdr *) ip_next(pip);
        bytes_left -= sizeof(struct sctphdr);

        /* Check for valid ports (zero valued ports would find partially initialised associations */
        if (sctp_hdr->src_port == 0 || sctp_hdr->dest_port == 0)
                return (SN_PARSE_ERROR_PORT);

        /* Check length of first chunk */
        if (bytes_left < SN_MIN_CHUNK_SIZE) /* malformed chunk - could cause endless loop*/
                return (SN_PARSE_ERROR_CHHL); /* packet not long enough for this chunk */

        /* First chunk */
        chunk_hdr = SN_SCTP_FIRSTCHUNK(sctp_hdr);

        chunk_length = SCTP_SIZE32(ntohs(chunk_hdr->chunk_length));
        if ((chunk_length < SN_MIN_CHUNK_SIZE) || (chunk_length > bytes_left)) /* malformed chunk - could cause endless loop*/
                return (SN_PARSE_ERROR_CHHL);

        if ((chunk_hdr->chunk_flags & SCTP_HAD_NO_TCB) &&
            ((chunk_hdr->chunk_type == SCTP_ABORT_ASSOCIATION) ||
                (chunk_hdr->chunk_type == SCTP_SHUTDOWN_COMPLETE))) {
                /* T-Bit set */
                if (direction == SN_TO_LOCAL)
                        *passoc = FindSctpGlobalT(la,  pip->ip_src, sctp_hdr->v_tag, sctp_hdr->dest_port, sctp_hdr->src_port);
                else
                        *passoc = FindSctpLocalT(la, pip->ip_dst, sctp_hdr->v_tag, sctp_hdr->dest_port, sctp_hdr->src_port);
        } else {
                /* Proper v_tag settings */
                if (direction == SN_TO_LOCAL)
                        *passoc = FindSctpGlobal(la, pip->ip_src, sctp_hdr->v_tag, sctp_hdr->src_port, sctp_hdr->dest_port, &partial_match);
                else
                        *passoc = FindSctpLocal(la, pip->ip_src,  pip->ip_dst, sctp_hdr->v_tag, sctp_hdr->src_port, sctp_hdr->dest_port);
        }

        chunk_count = 1;
        /* Real packet parsing occurs below */
        while (IS_SCTP_CONTROL(chunk_hdr)) {
                switch (chunk_hdr->chunk_type) {
                case SCTP_INITIATION:
                        if (chunk_length < sizeof(struct sctp_init_chunk)) /* malformed chunk*/
                                return (SN_PARSE_ERROR_CHHL);
                        sm->msg = SN_SCTP_INIT;
                        sm->sctpchnk.Init = (struct sctp_init *) ((char *) chunk_hdr + sizeof(struct sctp_chunkhdr));
                        sm->chunk_length = chunk_length;
                        /* if no existing association, create a new one */
                        if (*passoc == NULL) {
                                if (sctp_hdr->v_tag == 0) { //Init requires vtag=0
                                        *passoc = (struct sctp_nat_assoc *) sn_malloc(sizeof(struct sctp_nat_assoc));
                                        if (*passoc == NULL) {/* out of resources */
                                                return (SN_PARSE_ERROR_AS_MALLOC);
                                        }
                                        /* Initialize association - sn_malloc initializes memory to zeros */
                                        (*passoc)->state = SN_ID;
                                        LIST_INIT(&((*passoc)->Gaddr)); /* always initialise to avoid memory problems */
                                        (*passoc)->TableRegister = SN_NULL_TBL;
                                        return (SN_PARSE_OK);
                                }
                                return (SN_PARSE_ERROR_VTAG);
                        }
                        return (SN_PARSE_ERROR_LOOKUP);
                case SCTP_INITIATION_ACK:
                        if (chunk_length < sizeof(struct sctp_init_ack_chunk)) /* malformed chunk*/
                                return (SN_PARSE_ERROR_CHHL);
                        sm->msg = SN_SCTP_INITACK;
                        sm->sctpchnk.InitAck = (struct sctp_init_ack *) ((char *) chunk_hdr + sizeof(struct sctp_chunkhdr));
                        sm->chunk_length = chunk_length;
                        return ((*passoc == NULL) ? (SN_PARSE_ERROR_LOOKUP) : (SN_PARSE_OK));
                case SCTP_ABORT_ASSOCIATION: /* access only minimum sized chunk */
                        sm->msg = SN_SCTP_ABORT;
                        sm->chunk_length = chunk_length;
                        return ((*passoc == NULL) ? (SN_PARSE_ERROR_LOOKUP_ABORT) : (SN_PARSE_OK));
                case SCTP_SHUTDOWN_ACK:
                        if (chunk_length < sizeof(struct sctp_shutdown_ack_chunk)) /* malformed chunk*/
                                return (SN_PARSE_ERROR_CHHL);
                        if (sm->msg > SN_SCTP_SHUTACK) {
                                sm->msg = SN_SCTP_SHUTACK;
                                sm->chunk_length = chunk_length;
                        }
                        break;
                case SCTP_SHUTDOWN_COMPLETE:  /* minimum sized chunk */
                        if (sm->msg > SN_SCTP_SHUTCOMP) {
                                sm->msg = SN_SCTP_SHUTCOMP;
                                sm->chunk_length = chunk_length;
                        }
                        return ((*passoc == NULL) ? (SN_PARSE_ERROR_LOOKUP) : (SN_PARSE_OK));
                case SCTP_ASCONF:
                        if (sm->msg > SN_SCTP_ASCONF) {
                                if (chunk_length < (sizeof(struct  sctp_asconf_chunk) + sizeof(struct  sctp_ipv4addr_param))) /* malformed chunk*/
                                        return (SN_PARSE_ERROR_CHHL);
                                //leave parameter searching to later, if required
                                param_hdr = (struct sctp_paramhdr *) ((char *) chunk_hdr + sizeof(struct sctp_asconf_chunk)); /*compulsory IP parameter*/
                                if (ntohs(param_hdr->param_type) == SCTP_IPV4_ADDRESS) {
                                        if ((*passoc == NULL) && (direction == SN_TO_LOCAL)) { /* AddIP with no association */
                                                /* try look up with the ASCONF packet's alternative address */
                                                ipv4addr.s_addr = ((struct sctp_ipv4addr_param *) param_hdr)->addr;
                                                *passoc = FindSctpGlobal(la, ipv4addr, sctp_hdr->v_tag, sctp_hdr->src_port, sctp_hdr->dest_port, &partial_match);
                                        }
                                        param_hdr = (struct sctp_paramhdr *)
                                                ((char *) param_hdr + sizeof(struct sctp_ipv4addr_param)); /*asconf's compulsory address parameter */
                                        sm->chunk_length = chunk_length - sizeof(struct  sctp_asconf_chunk) - sizeof(struct  sctp_ipv4addr_param); /* rest of chunk */
                                } else {
                                        if (chunk_length < (sizeof(struct  sctp_asconf_chunk) + sizeof(struct  sctp_ipv6addr_param))) /* malformed chunk*/
                                                return (SN_PARSE_ERROR_CHHL);
                                        param_hdr = (struct sctp_paramhdr *)
                                                ((char *) param_hdr + sizeof(struct sctp_ipv6addr_param)); /*asconf's compulsory address parameter */
                                        sm->chunk_length = chunk_length - sizeof(struct  sctp_asconf_chunk) - sizeof(struct  sctp_ipv6addr_param); /* rest of chunk */
                                }
                                sm->msg = SN_SCTP_ASCONF;
                                sm->sctpchnk.Asconf = param_hdr;

                                if (*passoc == NULL) { /* AddIP with no association */
                                        *passoc = (struct sctp_nat_assoc *) sn_malloc(sizeof(struct sctp_nat_assoc));
                                        if (*passoc == NULL) {/* out of resources */
                                                return (SN_PARSE_ERROR_AS_MALLOC);
                                        }
                                        /* Initialize association  - sn_malloc initializes memory to zeros */
                                        (*passoc)->state = SN_ID;
                                        LIST_INIT(&((*passoc)->Gaddr)); /* always initialise to avoid memory problems */
                                        (*passoc)->TableRegister = SN_NULL_TBL;
                                        return (SN_PARSE_OK);
                                }
                        }
                        break;
                case SCTP_ASCONF_ACK:
                        if (sm->msg > SN_SCTP_ASCONFACK) {
                                if (chunk_length < sizeof(struct  sctp_asconf_ack_chunk)) /* malformed chunk*/
                                        return (SN_PARSE_ERROR_CHHL);
                                //leave parameter searching to later, if required
                                param_hdr = (struct sctp_paramhdr *) ((char *) chunk_hdr
                                    + sizeof(struct sctp_asconf_ack_chunk));
                                sm->msg = SN_SCTP_ASCONFACK;
                                sm->sctpchnk.Asconf = param_hdr;
                                sm->chunk_length = chunk_length - sizeof(struct sctp_asconf_ack_chunk);
                        }
                        break;
                default:
                        break; /* do nothing*/
                }

                /* if no association is found exit - we need to find an Init or AddIP within sysctl_initialising_chunk_proc_limit */
                if ((*passoc == NULL) && (chunk_count >= sysctl_initialising_chunk_proc_limit))
                        return (SN_PARSE_ERROR_LOOKUP);

                /* finished with this chunk, on to the next chunk*/
                bytes_left-= chunk_length;

                /* Is this the end of the packet ? */
                if (bytes_left == 0)
                        return (*passoc == NULL) ? (SN_PARSE_ERROR_LOOKUP) : (SN_PARSE_OK);

                /* Are there enough bytes in packet to at least retrieve length of next chunk ? */
                if (bytes_left < SN_MIN_CHUNK_SIZE)
                        return (SN_PARSE_ERROR_CHHL);

                chunk_hdr = SN_SCTP_NEXTCHUNK(chunk_hdr);

                /* Is the chunk long enough to not cause endless look and are there enough bytes in packet to read the chunk ? */
                chunk_length = SCTP_SIZE32(ntohs(chunk_hdr->chunk_length));
                if ((chunk_length < SN_MIN_CHUNK_SIZE) || (chunk_length > bytes_left))
                        return (SN_PARSE_ERROR_CHHL);
                if (++chunk_count > sysctl_chunk_proc_limit)
                        return (SN_PARSE_OK); /* limit for processing chunks, take what we get */
        }

        if (*passoc == NULL)
                return (partial_match) ? (SN_PARSE_ERROR_PARTIALLOOKUP) : (SN_PARSE_ERROR_LOOKUP);
        else
                return (SN_PARSE_OK);
}

/** @ingroup packet_parser
 * @brief Extract Vtags from Asconf Chunk
 *
 * GetAsconfVtags scans an Asconf Chunk for the vtags parameter, and then
 * extracts the vtags.
 *
 * GetAsconfVtags is not called from within sctp_PktParser. It is called only
 * from within ID_process when an AddIP has been received.
 *
 * @param la Pointer to the relevant libalias instance
 * @param sm Pointer to sctp message information
 * @param l_vtag Pointer to the local vtag in the association this SCTP Message belongs to
 * @param g_vtag Pointer to the local vtag in the association this SCTP Message belongs to
 * @param direction SN_TO_LOCAL | SN_TO_GLOBAL
 *
 * @return 1 - success | 0 - fail
 */
static int
GetAsconfVtags(struct libalias *la, struct sctp_nat_msg *sm, uint32_t *l_vtag, uint32_t *g_vtag, int direction)
{
        /* To be removed when information is in the sctp headers */
#define SCTP_VTAG_PARAM 0xC007
        struct sctp_vtag_param {
                struct sctp_paramhdr ph;/* type=SCTP_VTAG_PARAM */
                uint32_t local_vtag;
                uint32_t remote_vtag;
        } __attribute__((packed));

        struct sctp_vtag_param *vtag_param;
        struct sctp_paramhdr *param;
        int bytes_left;
        int param_size;
        int param_count;

        param_count = 1;
        param = sm->sctpchnk.Asconf;
        param_size = SCTP_SIZE32(ntohs(param->param_length));
        bytes_left = sm->chunk_length;
        /* step through Asconf parameters */
        while((bytes_left >= param_size) && (bytes_left >= SN_VTAG_PARAM_SIZE)) {
                if (ntohs(param->param_type) == SCTP_VTAG_PARAM) {
                        vtag_param = (struct sctp_vtag_param *) param;
                        switch (direction) {
                                /* The Internet draft is a little ambigious as to order of these vtags.
                                   We think it is this way around. If we are wrong, the order will need
                                   to be changed. */
                        case SN_TO_GLOBAL:
                                *g_vtag = vtag_param->local_vtag;
                                *l_vtag = vtag_param->remote_vtag;
                                break;
                        case SN_TO_LOCAL:
                                *g_vtag = vtag_param->remote_vtag;
                                *l_vtag = vtag_param->local_vtag;
                                break;
                        }
                        return (1); /* found */
                }

                bytes_left -= param_size;
                if (bytes_left < SN_MIN_PARAM_SIZE)
                        return (0);

                param = SN_SCTP_NEXTPARAM(param);
                param_size = SCTP_SIZE32(ntohs(param->param_length));
                if (++param_count > sysctl_param_proc_limit) {
                        SN_LOG(SN_LOG_EVENT,
                            logsctperror("Parameter parse limit exceeded (GetAsconfVtags)",
                                sm->sctp_hdr->v_tag, sysctl_param_proc_limit, direction));
                        return (0); /* not found limit exceeded*/
                }
        }
        return (0); /* not found */
}

/** @ingroup packet_parser
 * @brief AddGlobalIPAddresses from Init,InitAck,or AddIP packets
 *
 * AddGlobalIPAddresses scans an SCTP chunk (in sm) for Global IP addresses, and
 * adds them.
 *
 * @param sm Pointer to sctp message information
 * @param assoc Pointer to the association this SCTP Message belongs to
 * @param direction SN_TO_LOCAL | SN_TO_GLOBAL
 *
 */
static void
AddGlobalIPAddresses(struct sctp_nat_msg *sm, struct sctp_nat_assoc *assoc, int direction)
{
        struct sctp_ipv4addr_param *ipv4_param;
        struct sctp_paramhdr *param = NULL;
        struct sctp_GlobalAddress *G_Addr;
        struct in_addr g_addr = {0};
        int bytes_left = 0;
        int param_size;
        int param_count, addr_param_count = 0;

        switch (direction) {
        case SN_TO_GLOBAL: /* does not contain global addresses */
                g_addr = sm->ip_hdr->ip_dst;
                bytes_left = 0; /* force exit */
                break;
        case SN_TO_LOCAL:
                g_addr = sm->ip_hdr->ip_src;
                param_count = 1;
                switch (sm->msg) {
                case SN_SCTP_INIT:
                        bytes_left = sm->chunk_length - sizeof(struct sctp_init_chunk);
                        param = (struct sctp_paramhdr *)((char *)sm->sctpchnk.Init + sizeof(struct sctp_init));
                        break;
                case SN_SCTP_INITACK:
                        bytes_left = sm->chunk_length - sizeof(struct sctp_init_ack_chunk);
                        param = (struct sctp_paramhdr *)((char *)sm->sctpchnk.InitAck + sizeof(struct sctp_init_ack));
                        break;
                case SN_SCTP_ASCONF:
                        bytes_left = sm->chunk_length;
                        param = sm->sctpchnk.Asconf;
                        break;
                }
        }
        if (bytes_left >= SN_MIN_PARAM_SIZE)
                param_size = SCTP_SIZE32(ntohs(param->param_length));
        else
                param_size = bytes_left+1; /* force skip loop */

        if ((assoc->state == SN_ID) && ((sm->msg == SN_SCTP_INIT) || (bytes_left < SN_MIN_PARAM_SIZE))) {/* add pkt address */
                G_Addr = (struct sctp_GlobalAddress *) sn_malloc(sizeof(struct sctp_GlobalAddress));
                if (G_Addr == NULL) {/* out of resources */
                        SN_LOG(SN_LOG_EVENT,
                            logsctperror("AddGlobalIPAddress: No resources for adding global address - revert to no tracking",
                                sm->sctp_hdr->v_tag,  0, direction));
                        assoc->num_Gaddr = 0; /* don't track any more for this assoc*/
                        sysctl_track_global_addresses=0;
                        return;
                }
                G_Addr->g_addr = g_addr;
                if (!Add_Global_Address_to_List(assoc, G_Addr))
                        SN_LOG(SN_LOG_EVENT,
                            logsctperror("AddGlobalIPAddress: Address already in list",
                                sm->sctp_hdr->v_tag,  assoc->num_Gaddr, direction));
        }

        /* step through parameters */
        while((bytes_left >= param_size) && (bytes_left >= sizeof(struct sctp_ipv4addr_param))) {
                if (assoc->num_Gaddr >= sysctl_track_global_addresses) {
                        SN_LOG(SN_LOG_EVENT,
                            logsctperror("AddGlobalIPAddress: Maximum Number of addresses reached",
                                sm->sctp_hdr->v_tag,  sysctl_track_global_addresses, direction));
                        return;
                }
                switch (ntohs(param->param_type)) {
                case SCTP_ADD_IP_ADDRESS:
                        /* skip to address parameter - leave param_size so bytes left will be calculated properly*/
                        param = (struct sctp_paramhdr *) &((struct sctp_asconf_addrv4_param *) param)->addrp;
                        /* FALLTHROUGH */
                case SCTP_IPV4_ADDRESS:
                        ipv4_param = (struct sctp_ipv4addr_param *) param;
                        /* add addresses to association */
                        G_Addr = (struct sctp_GlobalAddress *) sn_malloc(sizeof(struct sctp_GlobalAddress));
                        if (G_Addr == NULL) {/* out of resources */
                                SN_LOG(SN_LOG_EVENT,
                                    logsctperror("AddGlobalIPAddress: No resources for adding global address - revert to no tracking",
                                        sm->sctp_hdr->v_tag,  0, direction));
                                assoc->num_Gaddr = 0; /* don't track any more for this assoc*/
                                sysctl_track_global_addresses=0;
                                return;
                        }
                        /* add address */
                        addr_param_count++;
                        if ((sm->msg == SN_SCTP_ASCONF) && (ipv4_param->addr == INADDR_ANY)) { /* use packet address */
                                G_Addr->g_addr = g_addr;
                                if (!Add_Global_Address_to_List(assoc, G_Addr))
                                        SN_LOG(SN_LOG_EVENT,
                                            logsctperror("AddGlobalIPAddress: Address already in list",
                                                sm->sctp_hdr->v_tag,  assoc->num_Gaddr, direction));
                                return; /*shouldn't be any other addresses if the zero address is given*/
                        } else {
                                G_Addr->g_addr.s_addr = ipv4_param->addr;
                                if (!Add_Global_Address_to_List(assoc, G_Addr))
                                        SN_LOG(SN_LOG_EVENT,
                                            logsctperror("AddGlobalIPAddress: Address already in list",
                                                sm->sctp_hdr->v_tag,  assoc->num_Gaddr, direction));
                        }
                }

                bytes_left -= param_size;
                if (bytes_left < SN_MIN_PARAM_SIZE)
                        break;

                param = SN_SCTP_NEXTPARAM(param);
                param_size = SCTP_SIZE32(ntohs(param->param_length));
                if (++param_count > sysctl_param_proc_limit) {
                        SN_LOG(SN_LOG_EVENT,
                            logsctperror("Parameter parse limit exceeded (AddGlobalIPAddress)",
                                sm->sctp_hdr->v_tag, sysctl_param_proc_limit, direction));
                        break; /* limit exceeded*/
                }
        }
        if (addr_param_count == 0) {
                SN_LOG(SN_LOG_DETAIL,
                    logsctperror("AddGlobalIPAddress: no address parameters to add",
                        sm->sctp_hdr->v_tag, assoc->num_Gaddr, direction));
        }
}

/**
 * @brief Add_Global_Address_to_List
 *
 * Adds a global IP address to an associations address list, if it is not
 * already there.  The first address added us usually the packet's address, and
 * is most likely to be used, so it is added at the beginning. Subsequent
 * addresses are added after this one.
 *
 * @param assoc Pointer to the association this SCTP Message belongs to
 * @param G_addr Pointer to the global address to add
 *
 * @return 1 - success | 0 - fail
 */
static int
Add_Global_Address_to_List(struct sctp_nat_assoc *assoc,  struct sctp_GlobalAddress *G_addr)
{
        struct sctp_GlobalAddress *iter_G_Addr = NULL, *first_G_Addr = NULL;
        first_G_Addr = LIST_FIRST(&(assoc->Gaddr));
        if (first_G_Addr == NULL) {
                LIST_INSERT_HEAD(&(assoc->Gaddr), G_addr, list_Gaddr); /* add new address to beginning of list*/
        } else {
                LIST_FOREACH(iter_G_Addr, &(assoc->Gaddr), list_Gaddr) {
                        if (G_addr->g_addr.s_addr == iter_G_Addr->g_addr.s_addr)
                                return (0); /* already exists, so don't add */
                }
                LIST_INSERT_AFTER(first_G_Addr, G_addr, list_Gaddr); /* add address to end of list*/
        }
        assoc->num_Gaddr++;
        return (1); /* success */
}

/** @ingroup packet_parser
 * @brief RmGlobalIPAddresses from DelIP packets
 *
 * RmGlobalIPAddresses scans an ASCONF chunk for DelIP parameters to remove the
 * given Global IP addresses from the association. It will not delete the
 * the address if it is a list of one address.
 *
 *
 * @param sm Pointer to sctp message information
 * @param assoc Pointer to the association this SCTP Message belongs to
 * @param direction SN_TO_LOCAL | SN_TO_GLOBAL
 *
 */
static void
RmGlobalIPAddresses(struct sctp_nat_msg *sm, struct sctp_nat_assoc *assoc, int direction)
{
        struct sctp_asconf_addrv4_param *asconf_ipv4_param;
        struct sctp_paramhdr *param;
        struct sctp_GlobalAddress *G_Addr, *G_Addr_tmp;
        int bytes_left;
        int param_size;
        int param_count;

        bytes_left = sm->chunk_length;
        param_count = 1;
        param = sm->sctpchnk.Asconf;
        if (bytes_left >= SN_MIN_PARAM_SIZE) {
                param_size = SCTP_SIZE32(ntohs(param->param_length));
        } else {
                SN_LOG(SN_LOG_EVENT,
                    logsctperror("RmGlobalIPAddress: truncated packet - cannot remove IP addresses",
                        sm->sctp_hdr->v_tag, sysctl_track_global_addresses, direction));
                return;
        }

        /* step through Asconf parameters */
        while((bytes_left >= param_size) && (bytes_left >= sizeof(struct sctp_ipv4addr_param))) {
                if (ntohs(param->param_type) == SCTP_DEL_IP_ADDRESS) {
                        asconf_ipv4_param = (struct sctp_asconf_addrv4_param *) param;
                        if (asconf_ipv4_param->addrp.addr == INADDR_ANY) { /* remove all bar pkt address */
                                LIST_FOREACH_SAFE(G_Addr, &(assoc->Gaddr), list_Gaddr, G_Addr_tmp) {
                                        if (G_Addr->g_addr.s_addr != sm->ip_hdr->ip_src.s_addr) {
                                                if (assoc->num_Gaddr > 1) { /* only delete if more than one */
                                                        LIST_REMOVE(G_Addr, list_Gaddr);
                                                        sn_free(G_Addr);
                                                        assoc->num_Gaddr--;
                                                } else {
                                                        SN_LOG(SN_LOG_EVENT,
                                                            logsctperror("RmGlobalIPAddress: Request to remove last IP address (didn't)",
                                                                sm->sctp_hdr->v_tag, assoc->num_Gaddr, direction));
                                                }
                                        }
                                }
                                return; /*shouldn't be any other addresses if the zero address is given*/
                        } else {
                                LIST_FOREACH_SAFE(G_Addr, &(assoc->Gaddr), list_Gaddr, G_Addr_tmp) {
                                        if (G_Addr->g_addr.s_addr == asconf_ipv4_param->addrp.addr) {
                                                if (assoc->num_Gaddr > 1) { /* only delete if more than one */
                                                        LIST_REMOVE(G_Addr, list_Gaddr);
                                                        sn_free(G_Addr);
                                                        assoc->num_Gaddr--;
                                                        break; /* Since add only adds new addresses, there should be no double entries */
                                                } else {
                                                        SN_LOG(SN_LOG_EVENT,
                                                            logsctperror("RmGlobalIPAddress: Request to remove last IP address (didn't)",
                                                                sm->sctp_hdr->v_tag, assoc->num_Gaddr, direction));
                                                }
                                        }
                                }
                        }
                }
                bytes_left -= param_size;
                if (bytes_left == 0)
                        return;
                else if (bytes_left < SN_MIN_PARAM_SIZE) {
                        SN_LOG(SN_LOG_EVENT,
                            logsctperror("RmGlobalIPAddress: truncated packet - may not have removed all IP addresses",
                                sm->sctp_hdr->v_tag, sysctl_track_global_addresses, direction));
                        return;
                }

                param = SN_SCTP_NEXTPARAM(param);
                param_size = SCTP_SIZE32(ntohs(param->param_length));
                if (++param_count > sysctl_param_proc_limit) {
                        SN_LOG(SN_LOG_EVENT,
                            logsctperror("Parameter parse limit exceeded (RmGlobalIPAddress)",
                                sm->sctp_hdr->v_tag, sysctl_param_proc_limit, direction));
                        return; /* limit exceeded*/
                }
        }
}

/**  @ingroup packet_parser
 * @brief Check that ASCONF was successful
 *
 * Each ASCONF configuration parameter carries a correlation ID which should be
 * matched with an ASCONFack. This is difficult for a NAT, since every
 * association could potentially have a number of outstanding ASCONF
 * configuration parameters, which should only be activated on receipt of the
 * ACK.
 *
 * Currently we only look for an ACK when the NAT is setting up a new
 * association (ie AddIP for a connection that the NAT does not know about
 * because the original Init went through a public interface or another NAT)
 * Since there is currently no connection on this path, there should be no other
 * ASCONF configuration parameters outstanding, so we presume that if there is
 * an ACK that it is responding to the AddIP and activate the new association.
 *
 * @param la Pointer to the relevant libalias instance
 * @param sm Pointer to sctp message information
 * @param direction SN_TO_LOCAL | SN_TO_GLOBAL
 *
 * @return 1 - success | 0 - fail
 */
static int
IsASCONFack(struct libalias *la, struct sctp_nat_msg *sm, int direction)
{
        struct sctp_paramhdr *param;
        int bytes_left;
        int param_size;
        int param_count;

        param_count = 1;
        param = sm->sctpchnk.Asconf;
        param_size = SCTP_SIZE32(ntohs(param->param_length));
        if (param_size == 8)
                return (1); /*success - default acknowledgement of everything */

        bytes_left = sm->chunk_length;
        if (bytes_left < param_size)
                return (0); /* not found */
        /* step through Asconf parameters */
        while(bytes_left >= SN_ASCONFACK_PARAM_SIZE) {
                if (ntohs(param->param_type) == SCTP_SUCCESS_REPORT)
                        return (1); /* success - but can't match correlation IDs - should only be one */
                /* check others just in case */
                bytes_left -= param_size;
                if (bytes_left >= SN_MIN_PARAM_SIZE)
                        param = SN_SCTP_NEXTPARAM(param);
                else
                        return (0);

                param_size = SCTP_SIZE32(ntohs(param->param_length));
                if (bytes_left < param_size)
                        return (0);

                if (++param_count > sysctl_param_proc_limit) {
                        SN_LOG(SN_LOG_EVENT,
                            logsctperror("Parameter parse limit exceeded (IsASCONFack)",
                                sm->sctp_hdr->v_tag, sysctl_param_proc_limit, direction));
                        return (0); /* not found limit exceeded*/
                }
        }
        return (0); /* not success */
}

/**  @ingroup packet_parser
 * @brief Check to see if ASCONF contains an Add IP or Del IP parameter
 *
 * IsADDorDEL scans an ASCONF packet to see if it contains an AddIP or DelIP
 * parameter
 *
 * @param la Pointer to the relevant libalias instance
 * @param sm Pointer to sctp message information
 * @param direction SN_TO_LOCAL | SN_TO_GLOBAL
 *
 * @return SCTP_ADD_IP_ADDRESS | SCTP_DEL_IP_ADDRESS | 0 - fail
 */
static int
IsADDorDEL(struct libalias *la, struct sctp_nat_msg *sm, int direction)
{
        struct sctp_paramhdr *param;
        int bytes_left;
        int param_size;
        int param_count;

        param_count = 1;
        param = sm->sctpchnk.Asconf;
        param_size = SCTP_SIZE32(ntohs(param->param_length));

        bytes_left = sm->chunk_length;
        if (bytes_left < param_size)
                return (0); /* not found */
        /* step through Asconf parameters */
        while(bytes_left >= SN_ASCONFACK_PARAM_SIZE) {
                if (ntohs(param->param_type) == SCTP_ADD_IP_ADDRESS)
                        return (SCTP_ADD_IP_ADDRESS);
                else if (ntohs(param->param_type) == SCTP_DEL_IP_ADDRESS)
                        return (SCTP_DEL_IP_ADDRESS);
                /* check others just in case */
                bytes_left -= param_size;
                if (bytes_left >= SN_MIN_PARAM_SIZE)
                        param = SN_SCTP_NEXTPARAM(param);
                else
                        return (0); /*Neither found */

                param_size = SCTP_SIZE32(ntohs(param->param_length));
                if (bytes_left < param_size)
                        return (0);

                if (++param_count > sysctl_param_proc_limit) {
                        SN_LOG(SN_LOG_EVENT,
                            logsctperror("Parameter parse limit exceeded IsADDorDEL)",
                                sm->sctp_hdr->v_tag, sysctl_param_proc_limit, direction));
                        return (0); /* not found limit exceeded*/
                }
        }
        return (0);  /*Neither found */
}

/* ----------------------------------------------------------------------
 *                            STATE MACHINE CODE
 * ----------------------------------------------------------------------
 */
/** @addtogroup state_machine
 *
 * The SCTP NAT State Machine functions will:
 * - Process an already parsed packet
 * - Use the existing NAT Hash Tables
 * - Determine the next state for the association
 * - Update the NAT Hash Tables and Timer Queues
 * - Return the appropriate action to take with the packet
 */
/** @ingroup state_machine
 * @brief Process SCTP message
 *
 * This function is the base state machine. It calls the processing engine for
 * each state.
 *
 * @param la Pointer to the relevant libalias instance
 * @param direction SN_TO_LOCAL | SN_TO_GLOBAL
 * @param sm Pointer to sctp message information
 * @param assoc Pointer to the association this SCTP Message belongs to
 *
 * @return SN_DROP_PKT | SN_NAT_PKT | SN_REPLY_ABORT | SN_REPLY_ERROR | SN_PROCESSING_ERROR
 */
static int
ProcessSctpMsg(struct libalias *la, int direction, struct sctp_nat_msg *sm, struct sctp_nat_assoc *assoc)
{
        int rtnval;

        switch (assoc->state) {
        case SN_ID: /* Idle */
                rtnval = ID_process(la, direction, assoc, sm);
                if (rtnval != SN_NAT_PKT) {
                        assoc->state = SN_RM;/* Mark for removal*/
                }
                return (rtnval);
        case SN_INi: /* Initialising - Init */
                return (INi_process(la, direction, assoc, sm));
        case SN_INa: /* Initialising - AddIP */
                return (INa_process(la, direction, assoc, sm));
        case SN_UP:  /* Association UP */
                return (UP_process(la, direction, assoc, sm));
        case SN_CL:  /* Association Closing */
                return (CL_process(la, direction, assoc, sm));
        }
        return (SN_PROCESSING_ERROR);
}

/** @ingroup state_machine
 * @brief Process SCTP message while in the Idle state
 *
 * This function looks for an Incoming INIT or AddIP message.
 *
 * All other SCTP messages are invalid when in SN_ID, and are dropped.
 *
 * @param la Pointer to the relevant libalias instance
 * @param direction SN_TO_LOCAL | SN_TO_GLOBAL
 * @param sm Pointer to sctp message information
 * @param assoc Pointer to the association this SCTP Message belongs to
 *
 * @return SN_NAT_PKT | SN_DROP_PKT | SN_REPLY_ABORT | SN_REPLY_ERROR
 */
static int
ID_process(struct libalias *la, int direction, struct sctp_nat_assoc *assoc, struct sctp_nat_msg *sm)
{
        switch (sm->msg) {
        case SN_SCTP_ASCONF:           /* a packet containing an ASCONF chunk with ADDIP */
                if (!sysctl_accept_global_ootb_addip && (direction == SN_TO_LOCAL))
                        return (SN_DROP_PKT);
                /* if this Asconf packet does not contain the Vtag parameters it is of no use in Idle state */
                if (!GetAsconfVtags(la, sm, &(assoc->l_vtag), &(assoc->g_vtag), direction))
                        return (SN_DROP_PKT);
                /* FALLTHROUGH */
        case SN_SCTP_INIT:            /* a packet containing an INIT chunk or an ASCONF AddIP */
                if (sysctl_track_global_addresses)
                        AddGlobalIPAddresses(sm, assoc, direction);
                switch (direction) {
                case SN_TO_GLOBAL:
                        assoc->l_addr = sm->ip_hdr->ip_src;
                        assoc->a_addr = FindAliasAddress(la, assoc->l_addr);
                        assoc->l_port = sm->sctp_hdr->src_port;
                        assoc->g_port = sm->sctp_hdr->dest_port;
                        if (sm->msg == SN_SCTP_INIT)
                                assoc->g_vtag = sm->sctpchnk.Init->initiate_tag;
                        if (AddSctpAssocGlobal(la, assoc)) /* DB clash: need to add dst address */
                                return ((sm->msg == SN_SCTP_INIT) ? SN_REPLY_ABORT : SN_REPLY_ERROR);
                        if (sm->msg == SN_SCTP_ASCONF) {
                                if (AddSctpAssocLocal(la, assoc, sm->ip_hdr->ip_dst)) /* DB clash */
                                        return (SN_REPLY_ERROR);
                                assoc->TableRegister |= SN_WAIT_TOLOCAL; /* wait for tolocal ack */
                        }
                break;
                case SN_TO_LOCAL:
                        assoc->l_addr = FindSctpRedirectAddress(la, sm);
                        assoc->a_addr = sm->ip_hdr->ip_dst;
                        assoc->l_port = sm->sctp_hdr->dest_port;
                        assoc->g_port = sm->sctp_hdr->src_port;
                        if (sm->msg == SN_SCTP_INIT)
                                assoc->l_vtag = sm->sctpchnk.Init->initiate_tag;
                        if (AddSctpAssocLocal(la, assoc, sm->ip_hdr->ip_src)) /* DB clash */
                                return ((sm->msg == SN_SCTP_INIT) ? SN_REPLY_ABORT : SN_REPLY_ERROR);
                        if (sm->msg == SN_SCTP_ASCONF) {
                                if (AddSctpAssocGlobal(la, assoc)) /* DB clash: need to add src address */
                                        return (SN_REPLY_ERROR);
                                assoc->TableRegister |= SN_WAIT_TOGLOBAL; /* wait for toglobal ack */
                        }
                        break;
                }
                assoc->state = (sm->msg == SN_SCTP_INIT) ? SN_INi : SN_INa;
                assoc->exp = SN_I_T(la);
                sctp_AddTimeOut(la,assoc);
                return (SN_NAT_PKT);
        default: /* Any other type of SCTP message is not valid in Idle */
                return (SN_DROP_PKT);
        }
        return (SN_DROP_PKT);/* shouldn't get here very bad: log, drop and hope for the best */
}

/** @ingroup state_machine
 * @brief Process SCTP message while waiting for an INIT-ACK message
 *
 * Only an INIT-ACK, resent INIT, or an ABORT SCTP packet are valid in this
 * state, all other packets are dropped.
 *
 * @param la Pointer to the relevant libalias instance
 * @param direction SN_TO_LOCAL | SN_TO_GLOBAL
 * @param sm Pointer to sctp message information
 * @param assoc Pointer to the association this SCTP Message belongs to
 *
 * @return SN_NAT_PKT | SN_DROP_PKT | SN_REPLY_ABORT
 */
static int
INi_process(struct libalias *la, int direction, struct sctp_nat_assoc *assoc, struct sctp_nat_msg *sm)
{
        switch (sm->msg) {
        case SN_SCTP_INIT:            /* a packet containing a retransmitted INIT chunk */
                sctp_ResetTimeOut(la, assoc, SN_I_T(la));
                return (SN_NAT_PKT);
        case SN_SCTP_INITACK:         /* a packet containing an INIT-ACK chunk */
                switch (direction) {
                case SN_TO_LOCAL:
                        if (assoc->num_Gaddr) /*If tracking global addresses for this association */
                                AddGlobalIPAddresses(sm, assoc, direction);
                        assoc->l_vtag = sm->sctpchnk.Init->initiate_tag;
                        if (AddSctpAssocLocal(la, assoc, sm->ip_hdr->ip_src)) { /* DB clash */
                                assoc->state = SN_RM;/* Mark for removal*/
                                return (SN_SEND_ABORT);
                        }
                        break;
                case SN_TO_GLOBAL:
                        assoc->l_addr = sm->ip_hdr->ip_src; // Only if not set in Init! *
                        assoc->g_vtag = sm->sctpchnk.Init->initiate_tag;
                        if (AddSctpAssocGlobal(la, assoc)) { /* DB clash */
                                assoc->state = SN_RM;/* Mark for removal*/
                                return (SN_SEND_ABORT);
                        }
                        break;
                }
                assoc->state = SN_UP;/* association established for NAT */
                sctp_ResetTimeOut(la,assoc, SN_U_T(la));
                return (SN_NAT_PKT);
        case SN_SCTP_ABORT:           /* a packet containing an ABORT chunk */
                assoc->state = SN_RM;/* Mark for removal*/
                return (SN_NAT_PKT);
        default:
                return (SN_DROP_PKT);
        }
        return (SN_DROP_PKT);/* shouldn't get here very bad: log, drop and hope for the best */
}

/** @ingroup state_machine
 * @brief Process SCTP message while waiting for an AddIp-ACK message
 *
 * Only an AddIP-ACK, resent AddIP, or an ABORT message are valid, all other
 * SCTP packets are dropped
 *
 * @param la Pointer to the relevant libalias instance
 * @param direction SN_TO_LOCAL | SN_TO_GLOBAL
 * @param sm Pointer to sctp message information
 * @param assoc Pointer to the association this SCTP Message belongs to
 *
 * @return SN_NAT_PKT | SN_DROP_PKT
 */
static int
INa_process(struct libalias *la, int direction,struct sctp_nat_assoc *assoc, struct sctp_nat_msg *sm)
{
        switch (sm->msg) {
        case SN_SCTP_ASCONF:           /* a packet containing an ASCONF chunk*/
                sctp_ResetTimeOut(la,assoc, SN_I_T(la));
                return (SN_NAT_PKT);
        case SN_SCTP_ASCONFACK:        /* a packet containing an ASCONF chunk with a ADDIP-ACK */
                switch (direction) {
                case SN_TO_LOCAL:
                        if (!(assoc->TableRegister & SN_WAIT_TOLOCAL)) /* wrong direction */
                                return (SN_DROP_PKT);
                        break;
                case SN_TO_GLOBAL:
                        if (!(assoc->TableRegister & SN_WAIT_TOGLOBAL)) /* wrong direction */
                                return (SN_DROP_PKT);
                }
                if (IsASCONFack(la,sm,direction)) {
                        assoc->TableRegister &= SN_BOTH_TBL; /* remove wait flags */
                        assoc->state = SN_UP; /* association established for NAT */
                        sctp_ResetTimeOut(la,assoc, SN_U_T(la));
                        return (SN_NAT_PKT);
                } else {
                        assoc->state = SN_RM;/* Mark for removal*/
                        return (SN_NAT_PKT);
                }
        case SN_SCTP_ABORT:           /* a packet containing an ABORT chunk */
                assoc->state = SN_RM;/* Mark for removal*/
                return (SN_NAT_PKT);
        default:
                return (SN_DROP_PKT);
        }
        return (SN_DROP_PKT);/* shouldn't get here very bad: log, drop and hope for the best */
}

/** @ingroup state_machine
 * @brief Process SCTP messages while association is UP redirecting packets
 *
 * While in the SN_UP state, all packets for the particular association
 * are passed. Only a SHUT-ACK or an ABORT will cause a change of state.
 *
 * @param la Pointer to the relevant libalias instance
 * @param direction SN_TO_LOCAL | SN_TO_GLOBAL
 * @param sm Pointer to sctp message information
 * @param assoc Pointer to the association this SCTP Message belongs to
 *
 * @return SN_NAT_PKT | SN_DROP_PKT
 */
static int
UP_process(struct libalias *la, int direction, struct sctp_nat_assoc *assoc, struct sctp_nat_msg *sm)
{
        switch (sm->msg) {
        case SN_SCTP_SHUTACK:         /* a packet containing a SHUTDOWN-ACK chunk */
                assoc->state = SN_CL;
                sctp_ResetTimeOut(la,assoc, SN_C_T(la));
                return (SN_NAT_PKT);
        case SN_SCTP_ABORT:           /* a packet containing an ABORT chunk */
                assoc->state = SN_RM;/* Mark for removal*/
                return (SN_NAT_PKT);
        case SN_SCTP_ASCONF:           /* a packet containing an ASCONF chunk*/
                if ((direction == SN_TO_LOCAL) && assoc->num_Gaddr) /*If tracking global addresses for this association & from global side */
                        switch (IsADDorDEL(la,sm,direction)) {
                        case SCTP_ADD_IP_ADDRESS:
                                AddGlobalIPAddresses(sm, assoc, direction);
                                break;
                        case SCTP_DEL_IP_ADDRESS:
                                RmGlobalIPAddresses(sm, assoc, direction);
                                break;
                        }
                /* FALLTHROUGH */
        default:
                sctp_ResetTimeOut(la,assoc, SN_U_T(la));
                return (SN_NAT_PKT);  /* forward packet */
        }
        return (SN_DROP_PKT);/* shouldn't get here very bad: log, drop and hope for the best */
}

/** @ingroup state_machine
 * @brief Process SCTP message while association is in the process of closing
 *
 * This function waits for a SHUT-COMP to close the association. Depending on
 * the setting of sysctl_holddown_timer it may not remove the association
 * immediately, but leave it up until SN_X_T(la). Only SHUT-COMP, SHUT-ACK, and
 * ABORT packets are permitted in this state. All other packets are dropped.
 *
 * @param la Pointer to the relevant libalias instance
 * @param direction SN_TO_LOCAL | SN_TO_GLOBAL
 * @param sm Pointer to sctp message information
 * @param assoc Pointer to the association this SCTP Message belongs to
 *
 * @return SN_NAT_PKT | SN_DROP_PKT
 */
static int
CL_process(struct libalias *la, int direction,struct sctp_nat_assoc *assoc, struct sctp_nat_msg *sm)
{
        switch (sm->msg) {
        case SN_SCTP_SHUTCOMP:        /* a packet containing a SHUTDOWN-COMPLETE chunk */
                assoc->state = SN_CL;  /* Stay in Close state until timeout */
                if (sysctl_holddown_timer > 0)
                        sctp_ResetTimeOut(la, assoc, SN_X_T(la));/* allow to stay open for Tbit packets*/
                else
                        assoc->state = SN_RM;/* Mark for removal*/
                return (SN_NAT_PKT);
        case SN_SCTP_SHUTACK:         /* a packet containing a SHUTDOWN-ACK chunk */
                assoc->state = SN_CL;  /* Stay in Close state until timeout */
                sctp_ResetTimeOut(la, assoc, SN_C_T(la));
                return (SN_NAT_PKT);
        case SN_SCTP_ABORT:           /* a packet containing an ABORT chunk */
                assoc->state = SN_RM;/* Mark for removal*/
                return (SN_NAT_PKT);
        default:
                return (SN_DROP_PKT);
        }
        return (SN_DROP_PKT);/* shouldn't get here very bad: log, drop and hope for the best */
}

/* ----------------------------------------------------------------------
 *                           HASH TABLE CODE
 * ----------------------------------------------------------------------
 */
/** @addtogroup Hash
 *
 * The Hash functions facilitate searching the NAT Hash Tables for associations
 * as well as adding/removing associations from the table(s).
 */
/** @ingroup Hash
 * @brief Find the SCTP association given the local address, port and vtag
 *
 * Searches the local look-up table for the association entry matching the
 * provided local <address:ports:vtag> tuple
 *
 * @param la Pointer to the relevant libalias instance
 * @param l_addr local address
 * @param g_addr global address
 * @param l_vtag local Vtag
 * @param l_port local Port
 * @param g_port global Port
 *
 * @return pointer to association or NULL
 */
static struct sctp_nat_assoc *
FindSctpLocal(struct libalias *la, struct in_addr l_addr, struct in_addr g_addr, uint32_t l_vtag, uint16_t l_port, uint16_t g_port)
{
        u_int i;
        struct sctp_nat_assoc *assoc = NULL;
        struct sctp_GlobalAddress *G_Addr = NULL;

        if (l_vtag != 0) { /* an init packet, vtag==0 */
                i = SN_TABLE_HASH(l_vtag, l_port, la->sctpNatTableSize);
                LIST_FOREACH(assoc, &la->sctpTableLocal[i], list_L) {
                        if ((assoc->l_vtag == l_vtag) && (assoc->l_port == l_port) && (assoc->g_port == g_port)\
                            && (assoc->l_addr.s_addr == l_addr.s_addr)) {
                                if (assoc->num_Gaddr) {
                                        LIST_FOREACH(G_Addr, &(assoc->Gaddr), list_Gaddr) {
                                                if (G_Addr->g_addr.s_addr == g_addr.s_addr)
                                                        return (assoc);
                                        }
                                } else {
                                        return (assoc);
                                }
                        }
                }
        }
        return (NULL);
}

/** @ingroup Hash
 * @brief Check for Global Clash
 *
 * Searches the global look-up table for the association entry matching the
 * provided global <(addresses):ports:vtag> tuple
 *
 * @param la Pointer to the relevant libalias instance
 * @param Cassoc association being checked for a clash
 *
 * @return pointer to association or NULL
 */
static struct sctp_nat_assoc *
FindSctpGlobalClash(struct libalias *la, struct sctp_nat_assoc *Cassoc)
{
        u_int i;
        struct sctp_nat_assoc *assoc = NULL;
        struct sctp_GlobalAddress *G_Addr = NULL;
        struct sctp_GlobalAddress *G_AddrC = NULL;

        if (Cassoc->g_vtag != 0) { /* an init packet, vtag==0 */
                i = SN_TABLE_HASH(Cassoc->g_vtag, Cassoc->g_port, la->sctpNatTableSize);
                LIST_FOREACH(assoc, &la->sctpTableGlobal[i], list_G) {
                        if ((assoc->g_vtag == Cassoc->g_vtag) && (assoc->g_port == Cassoc->g_port) && (assoc->l_port == Cassoc->l_port)) {
                                if (assoc->num_Gaddr) {
                                        LIST_FOREACH(G_AddrC, &(Cassoc->Gaddr), list_Gaddr) {
                                                LIST_FOREACH(G_Addr, &(assoc->Gaddr), list_Gaddr) {
                                                        if (G_Addr->g_addr.s_addr == G_AddrC->g_addr.s_addr)
                                                                return (assoc);
                                                }
                                        }
                                } else {
                                        return (assoc);
                                }
                        }
                }
        }
        return (NULL);
}

/** @ingroup Hash
 * @brief Find the SCTP association given the global port and vtag
 *
 * Searches the global look-up table for the association entry matching the
 * provided global <address:ports:vtag> tuple
 *
 * If all but the global address match it sets partial_match to 1 to indicate a
 * partial match. If the NAT is tracking global IP addresses for this
 * association, the NAT may respond with an ERRORM to request the missing
 * address to be added.
 *
 * @param la Pointer to the relevant libalias instance
 * @param g_addr global address
 * @param g_vtag global vtag
 * @param g_port global port
 * @param l_port local port
 *
 * @return pointer to association or NULL
 */
static struct sctp_nat_assoc *
FindSctpGlobal(struct libalias *la, struct in_addr g_addr, uint32_t g_vtag, uint16_t g_port, uint16_t l_port, int *partial_match)
{
        u_int i;
        struct sctp_nat_assoc *assoc = NULL;
        struct sctp_GlobalAddress *G_Addr = NULL;

        *partial_match = 0;
        if (g_vtag != 0) { /* an init packet, vtag==0 */
                i = SN_TABLE_HASH(g_vtag, g_port, la->sctpNatTableSize);
                LIST_FOREACH(assoc, &la->sctpTableGlobal[i], list_G) {
                        if ((assoc->g_vtag == g_vtag) && (assoc->g_port == g_port) && (assoc->l_port == l_port)) {
                                *partial_match = 1;
                                if (assoc->num_Gaddr) {
                                        LIST_FOREACH(G_Addr, &(assoc->Gaddr), list_Gaddr) {
                                                if (G_Addr->g_addr.s_addr == g_addr.s_addr)
                                                        return (assoc);
                                        }
                                } else {
                                        return (assoc);
                                }
                        }
                }
        }
        return (NULL);
}

/** @ingroup Hash
 * @brief Find the SCTP association for a T-Flag message (given the global port and local vtag)
 *
 * Searches the local look-up table for a unique association entry matching the
 * provided global port and local vtag information
 *
 * @param la Pointer to the relevant libalias instance
 * @param g_addr global address
 * @param l_vtag local Vtag
 * @param g_port global Port
 * @param l_port local Port
 *
 * @return pointer to association or NULL
 */
static struct sctp_nat_assoc *
FindSctpLocalT(struct libalias *la, struct in_addr g_addr, uint32_t l_vtag, uint16_t g_port, uint16_t l_port)
{
        u_int i;
        struct sctp_nat_assoc *assoc = NULL, *lastmatch = NULL;
        struct sctp_GlobalAddress *G_Addr = NULL;
        int cnt = 0;

        if (l_vtag != 0) { /* an init packet, vtag==0 */
                i = SN_TABLE_HASH(l_vtag, g_port, la->sctpNatTableSize);
                LIST_FOREACH(assoc, &la->sctpTableGlobal[i], list_G) {
                        if ((assoc->g_vtag == l_vtag) && (assoc->g_port == g_port) && (assoc->l_port == l_port)) {
                                if (assoc->num_Gaddr) {
                                        LIST_FOREACH(G_Addr, &(assoc->Gaddr), list_Gaddr) {
                                                if (G_Addr->g_addr.s_addr == g_addr.s_addr)
                                                        return (assoc); /* full match */
                                        }
                                } else {
                                        if (++cnt > 1)
                                                return (NULL);
                                        lastmatch = assoc;
                                }
                        }
                }
        }
        /* If there is more than one match we do not know which local address to send to */
        return (cnt ? lastmatch : NULL);
}

/** @ingroup Hash
 * @brief Find the SCTP association for a T-Flag message (given the local port and global vtag)
 *
 * Searches the global look-up table for a unique association entry matching the
 * provided local port and global vtag information
 *
 * @param la Pointer to the relevant libalias instance
 * @param g_addr global address
 * @param g_vtag global vtag
 * @param l_port local port
 * @param g_port global port
 *
 * @return pointer to association or NULL
 */
static struct sctp_nat_assoc *
FindSctpGlobalT(struct libalias *la, struct in_addr g_addr, uint32_t g_vtag, uint16_t l_port, uint16_t g_port)
{
        u_int i;
        struct sctp_nat_assoc *assoc = NULL;
        struct sctp_GlobalAddress *G_Addr = NULL;

        if (g_vtag != 0) { /* an init packet, vtag==0 */
                i = SN_TABLE_HASH(g_vtag, l_port, la->sctpNatTableSize);
                LIST_FOREACH(assoc, &la->sctpTableLocal[i], list_L) {
                        if ((assoc->l_vtag == g_vtag) && (assoc->l_port == l_port) && (assoc->g_port == g_port)) {
                                if (assoc->num_Gaddr) {
                                        LIST_FOREACH(G_Addr, &(assoc->Gaddr), list_Gaddr) {
                                                if (G_Addr->g_addr.s_addr == g_addr.s_addr)
                                                        return (assoc);
                                        }
                                } else {
                                        return (assoc);
                                }
                        }
                }
        }
        return (NULL);
}

/** @ingroup Hash
 * @brief  Add the sctp association information to the local look up table
 *
 * Searches the local look-up table for an existing association with the same
 * details. If a match exists and is ONLY in the local look-up table then this
 * is a repeated INIT packet, we need to remove this association from the
 * look-up table and add the new association
 *
 * The new association is added to the head of the list and state is updated
 *
 * @param la Pointer to the relevant libalias instance
 * @param assoc pointer to sctp association
 * @param g_addr global address
 *
 * @return SN_ADD_OK | SN_ADD_CLASH
 */
static int
AddSctpAssocLocal(struct libalias *la, struct sctp_nat_assoc *assoc, struct in_addr g_addr)
{
        struct sctp_nat_assoc *found;

        LIBALIAS_LOCK_ASSERT(la);
        found = FindSctpLocal(la, assoc->l_addr, g_addr, assoc->l_vtag, assoc->l_port, assoc->g_port);
        /*
         * Note that if a different global address initiated this Init,
         * ie it wasn't resent as presumed:
         *  - the local receiver if receiving it for the first time will establish
         *    an association with the new global host
         *  - if receiving an init from a different global address after sending a
         *    lost initack it will send an initack to the new global host, the first
         *    association attempt will then be blocked if retried.
         */
        if (found != NULL) {
                if ((found->TableRegister == SN_LOCAL_TBL) && (found->g_port == assoc->g_port)) { /* resent message */
                        RmSctpAssoc(la, found);
                        sctp_RmTimeOut(la, found);
                        freeGlobalAddressList(found);
                        sn_free(found);
                } else
                        return (SN_ADD_CLASH);
        }

        LIST_INSERT_HEAD(&la->sctpTableLocal[SN_TABLE_HASH(assoc->l_vtag, assoc->l_port, la->sctpNatTableSize)],
            assoc, list_L);
        assoc->TableRegister |= SN_LOCAL_TBL;
        la->sctpLinkCount++; //increment link count

        if (assoc->TableRegister == SN_BOTH_TBL) {
                /* libalias log -- controlled by libalias */
                if (la->packetAliasMode & PKT_ALIAS_LOG)
                        SctpShowAliasStats(la);

                SN_LOG(SN_LOG_INFO, logsctpassoc(assoc, "^"));
        }

        return (SN_ADD_OK);
}

/** @ingroup Hash
 * @brief  Add the sctp association information to the global look up table
 *
 * Searches the global look-up table for an existing association with the same
 * details. If a match exists and is ONLY in the global look-up table then this
 * is a repeated INIT packet, we need to remove this association from the
 * look-up table and add the new association
 *
 * The new association is added to the head of the list and state is updated
 *
 * @param la Pointer to the relevant libalias instance
 * @param assoc pointer to sctp association
 *
 * @return SN_ADD_OK | SN_ADD_CLASH
 */
static int
AddSctpAssocGlobal(struct libalias *la, struct sctp_nat_assoc *assoc)
{
        struct sctp_nat_assoc *found;

        LIBALIAS_LOCK_ASSERT(la);
        found = FindSctpGlobalClash(la, assoc);
        if (found != NULL) {
                if ((found->TableRegister == SN_GLOBAL_TBL) &&
                    (found->l_addr.s_addr == assoc->l_addr.s_addr) &&
                    (found->l_port == assoc->l_port)) { /* resent message */
                        RmSctpAssoc(la, found);
                        sctp_RmTimeOut(la, found);
                        freeGlobalAddressList(found);
                        sn_free(found);
                } else
                        return (SN_ADD_CLASH);
        }

        LIST_INSERT_HEAD(&la->sctpTableGlobal[SN_TABLE_HASH(assoc->g_vtag, assoc->g_port, la->sctpNatTableSize)],
            assoc, list_G);
        assoc->TableRegister |= SN_GLOBAL_TBL;
        la->sctpLinkCount++; //increment link count

        if (assoc->TableRegister == SN_BOTH_TBL) {
                /* libalias log -- controlled by libalias */
                if (la->packetAliasMode & PKT_ALIAS_LOG)
                        SctpShowAliasStats(la);

                SN_LOG(SN_LOG_INFO, logsctpassoc(assoc, "^"));
        }

        return (SN_ADD_OK);
}

/** @ingroup Hash
 * @brief Remove the sctp association information from the look up table
 *
 * For each of the two (local/global) look-up tables, remove the association
 * from that table IF it has been registered in that table.
 *
 * NOTE: The calling code is responsible for freeing memory allocated to the
 *       association structure itself
 *
 * NOTE: The association is NOT removed from the timer queue
 *
 * @param la Pointer to the relevant libalias instance
 * @param assoc pointer to sctp association
 */
static void
RmSctpAssoc(struct libalias *la, struct sctp_nat_assoc *assoc)
{
        //  struct sctp_nat_assoc *found;
        if (assoc == NULL) {
                /* very bad, log and die*/
                SN_LOG(SN_LOG_LOW,
                    logsctperror("ERROR: alias_sctp:RmSctpAssoc(NULL)\n", 0, 0, SN_TO_NODIR));
                return;
        }
        /* log if association is fully up and now closing */
        if (assoc->TableRegister == SN_BOTH_TBL) {
                SN_LOG(SN_LOG_INFO, logsctpassoc(assoc, "$"));
        }
        LIBALIAS_LOCK_ASSERT(la);
        if (assoc->TableRegister & SN_LOCAL_TBL) {
                assoc->TableRegister ^= SN_LOCAL_TBL;
                la->sctpLinkCount--; //decrement link count
                LIST_REMOVE(assoc, list_L);
        }

        if (assoc->TableRegister & SN_GLOBAL_TBL) {
                assoc->TableRegister ^= SN_GLOBAL_TBL;
                la->sctpLinkCount--; //decrement link count
                LIST_REMOVE(assoc, list_G);
        }
        //  sn_free(assoc); //Don't remove now, remove if needed later
        /* libalias logging -- controlled by libalias log definition */
        if (la->packetAliasMode & PKT_ALIAS_LOG)
                SctpShowAliasStats(la);
}

/**
 * @ingroup Hash
 * @brief  free the Global Address List memory
 *
 * freeGlobalAddressList deletes all global IP addresses in an associations
 * global IP address list.
 *
 * @param assoc
 */
static void freeGlobalAddressList(struct sctp_nat_assoc *assoc)
{
        struct sctp_GlobalAddress *gaddr1=NULL,*gaddr2=NULL;
        /*free global address list*/
        gaddr1 = LIST_FIRST(&(assoc->Gaddr));
        while (gaddr1 != NULL) {
                gaddr2 = LIST_NEXT(gaddr1, list_Gaddr);
                sn_free(gaddr1);
                gaddr1 = gaddr2;
        }
}
/* ----------------------------------------------------------------------
 *                            TIMER QUEUE CODE
 * ----------------------------------------------------------------------
 */
/** @addtogroup Timer
 *
 * The timer queue management functions are designed to operate efficiently with
 * a minimum of interaction with the queues.
 *
 * Once a timeout is set in the queue it will not be altered in the queue unless
 * it has to be changed to a shorter time (usually only for aborts and closing).
 * On a queue timeout, the real expiry time is checked, and if not leq than the
 * timeout it is requeued (O(1)) at its later time. This is especially important
 * for normal packets sent during an association. When a timer expires, it is
 * updated to its new expiration time if necessary, or processed as a
 * timeout. This means that while in UP state, the timing queue is only altered
 * every U_T (every few minutes) for a particular association.
 */
/** @ingroup Timer
 * @brief Add an association timeout to the timer queue
 *
 * Determine the location in the queue to add the timeout and insert the
 * association into the list at that queue position
 *
 * @param la
 * @param assoc
 */
static void
sctp_AddTimeOut(struct libalias *la, struct sctp_nat_assoc *assoc)
{
        int add_loc;
        LIBALIAS_LOCK_ASSERT(la);
        add_loc = assoc->exp - la->sctpNatTimer.loc_time + la->sctpNatTimer.cur_loc;
        if (add_loc >= SN_TIMER_QUEUE_SIZE)
                add_loc -= SN_TIMER_QUEUE_SIZE;
        LIST_INSERT_HEAD(&la->sctpNatTimer.TimerQ[add_loc], assoc, timer_Q);
        assoc->exp_loc = add_loc;
}

/** @ingroup Timer
 * @brief Remove an association from timer queue
 *
 * This is an O(1) operation to remove the association pointer from its
 * current position in the timer queue
 *
 * @param la Pointer to the relevant libalias instance
 * @param assoc pointer to sctp association
 */
static void
sctp_RmTimeOut(struct libalias *la, struct sctp_nat_assoc *assoc)
{
        LIBALIAS_LOCK_ASSERT(la);
        LIST_REMOVE(assoc, timer_Q);/* Note this is O(1) */
}

/** @ingroup Timer
 * @brief Reset timer in timer queue
 *
 * Reset the actual timeout for the specified association. If it is earlier than
 * the existing timeout, then remove and re-install the association into the
 * queue
 *
 * @param la Pointer to the relevant libalias instance
 * @param assoc pointer to sctp association
 * @param newexp New expiration time
 */
static void
sctp_ResetTimeOut(struct libalias *la, struct sctp_nat_assoc *assoc, int newexp)
{
        if (newexp < assoc->exp) {
                sctp_RmTimeOut(la, assoc);
                assoc->exp = newexp;
                sctp_AddTimeOut(la, assoc);
        } else {
                assoc->exp = newexp;
        }
}

/** @ingroup Timer
 * @brief Check timer Q against current time
 *
 * Loop through each entry in the timer queue since the last time we processed
 * the timer queue until now (the current time). For each association in the
 * event list, we remove it from that position in the timer queue and check if
 * it has really expired. If so we:
 * - Log the timer expiry
 * - Remove the association from the NAT tables
 * - Release the memory used by the association
 *
 * If the timer hasn't really expired we place the association into its new
 * correct position in the timer queue.
 *
 * @param la  Pointer to the relevant libalias instance
 */
void
sctp_CheckTimers(struct libalias *la)
{
        struct sctp_nat_assoc *assoc;

        LIBALIAS_LOCK_ASSERT(la);
        while(LibAliasTime >= la->sctpNatTimer.loc_time) {
                while (!LIST_EMPTY(&la->sctpNatTimer.TimerQ[la->sctpNatTimer.cur_loc])) {
                        assoc = LIST_FIRST(&la->sctpNatTimer.TimerQ[la->sctpNatTimer.cur_loc]);
                        //SLIST_REMOVE_HEAD(&la->sctpNatTimer.TimerQ[la->sctpNatTimer.cur_loc], timer_Q);
                        LIST_REMOVE(assoc, timer_Q);
                        if (LibAliasTime >= assoc->exp) { /* state expired */
                                SN_LOG(((assoc->state == SN_CL) ? (SN_LOG_DEBUG) : (SN_LOG_INFO)),
                                    logsctperror("Timer Expired", assoc->g_vtag, assoc->state, SN_TO_NODIR));
                                RmSctpAssoc(la, assoc);
                                freeGlobalAddressList(assoc);
                                sn_free(assoc);
                        } else {/* state not expired, reschedule timer*/
                                sctp_AddTimeOut(la, assoc);
                        }
                }
                /* Goto next location in the timer queue*/
                ++la->sctpNatTimer.loc_time;
                if (++la->sctpNatTimer.cur_loc >= SN_TIMER_QUEUE_SIZE)
                        la->sctpNatTimer.cur_loc = 0;
        }
}

/* ----------------------------------------------------------------------
 *                              LOGGING CODE
 * ----------------------------------------------------------------------
 */
/** @addtogroup Logging
 *
 * The logging functions provide logging of different items ranging from logging
 * a simple message, through logging an association details to logging the
 * current state of the NAT tables
 */
/** @ingroup Logging
 * @brief Log sctp nat errors
 *
 * @param errormsg Error message to be logged
 * @param vtag Current Vtag
 * @param error Error number
 * @param direction Direction of packet
 */
static void
logsctperror(char *errormsg, uint32_t vtag, int error, int direction)
{
        char dir;
        switch (direction) {
        case SN_TO_LOCAL:
                dir = 'L';
                break;
        case SN_TO_GLOBAL:
                dir = 'G';
                break;
        default:
                dir = '*';
                break;
        }
        SctpAliasLog("->%c %s (vt=%u) %d\n", dir, errormsg, ntohl(vtag), error);
}

/** @ingroup Logging
 * @brief Log what the parser parsed
 *
 * @param direction Direction of packet
 * @param sm Pointer to sctp message information
 */
static void
logsctpparse(int direction, struct sctp_nat_msg *sm)
{
        char *ploc, *pstate;
        switch (direction) {
        case SN_TO_LOCAL:
                ploc = "TO_LOCAL -";
                break;
        case SN_TO_GLOBAL:
                ploc = "TO_GLOBAL -";
                break;
        default:
                ploc = "";
        }
        switch (sm->msg) {
        case SN_SCTP_INIT:
                pstate = "Init";
                break;
        case SN_SCTP_INITACK:
                pstate = "InitAck";
                break;
        case SN_SCTP_ABORT:
                pstate = "Abort";
                break;
        case SN_SCTP_SHUTACK:
                pstate = "ShutAck";
                break;
        case SN_SCTP_SHUTCOMP:
                pstate = "ShutComp";
                break;
        case SN_SCTP_ASCONF:
                pstate = "Asconf";
                break;
        case SN_SCTP_ASCONFACK:
                pstate = "AsconfAck";
                break;
        case SN_SCTP_OTHER:
                pstate = "Other";
                break;
        default:
                pstate = "***ERROR***";
                break;
        }
        SctpAliasLog("Parsed: %s %s\n", ploc, pstate);
}

/** @ingroup Logging
 * @brief Log an SCTP association's details
 *
 * @param assoc pointer to sctp association
 * @param s Character that indicates the state of processing for this packet
 */
static void logsctpassoc(struct sctp_nat_assoc *assoc, char *s)
{
        struct sctp_GlobalAddress *G_Addr = NULL;
        char *sp;
        char addrbuf[INET_ADDRSTRLEN];

        switch (assoc->state) {
        case SN_ID:
                sp = "ID ";
                break;
        case SN_INi:
                sp = "INi ";
                break;
        case SN_INa:
                sp = "INa ";
                break;
        case SN_UP:
                sp = "UP ";
                break;
        case SN_CL:
                sp = "CL ";
                break;
        case SN_RM:
                sp = "RM ";
                break;
        default:
                sp = "***ERROR***";
                break;
        }
        SctpAliasLog("%sAssoc: %s exp=%u la=%s lv=%u lp=%u gv=%u gp=%u tbl=%d\n",
            s, sp, assoc->exp, inet_ntoa_r(assoc->l_addr, addrbuf),
            ntohl(assoc->l_vtag), ntohs(assoc->l_port),
            ntohl(assoc->g_vtag), ntohs(assoc->g_port),
            assoc->TableRegister);
        /* list global addresses */
        LIST_FOREACH(G_Addr, &(assoc->Gaddr), list_Gaddr) {
                SctpAliasLog("\t\tga=%s\n",
                    inet_ntoa_r(G_Addr->g_addr, addrbuf));
        }
}

/** @ingroup Logging
 * @brief Output Global table to log
 *
 * @param la Pointer to the relevant libalias instance
 */
static void logSctpGlobal(struct libalias *la)
{
        u_int i;
        struct sctp_nat_assoc *assoc = NULL;

        SctpAliasLog("G->\n");
        for (i = 0; i < la->sctpNatTableSize; i++) {
                LIST_FOREACH(assoc, &la->sctpTableGlobal[i], list_G) {
                        logsctpassoc(assoc, " ");
                }
        }
}

/** @ingroup Logging
 * @brief  Output Local table to log
 *
 * @param la Pointer to the relevant libalias instance
 */
static void logSctpLocal(struct libalias *la)
{
        u_int i;
        struct sctp_nat_assoc *assoc = NULL;

        SctpAliasLog("L->\n");
        for (i = 0; i < la->sctpNatTableSize; i++) {
                LIST_FOREACH(assoc, &la->sctpTableLocal[i], list_L) {
                        logsctpassoc(assoc, " ");
                }
        }
}

/** @ingroup Logging
 * @brief Output timer queue to log
 *
 * @param la Pointer to the relevant libalias instance
 */
static void logTimerQ(struct libalias *la)
{
        static char buf[50];
        u_int i;
        struct sctp_nat_assoc *assoc = NULL;

        SctpAliasLog("t->\n");
        for (i = 0; i < SN_TIMER_QUEUE_SIZE; i++) {
                LIST_FOREACH(assoc, &la->sctpNatTimer.TimerQ[i], timer_Q) {
                        snprintf(buf, 50, " l=%u ",i);
                        //SctpAliasLog(la->logDesc," l=%d ",i);
                        logsctpassoc(assoc, buf);
                }
        }
}

/** @ingroup Logging
 * @brief Sctp NAT logging function
 *
 * This function is based on a similar function in alias_db.c
 *
 * @param str/stream logging descriptor
 * @param format printf type string
 */
#ifdef _KERNEL
static void
SctpAliasLog(const char *format, ...)
{
        char buffer[LIBALIAS_BUF_SIZE];
        va_list ap;
        va_start(ap, format);
        vsnprintf(buffer, LIBALIAS_BUF_SIZE, format, ap);
        va_end(ap);
        log(LOG_SECURITY | LOG_INFO, "alias_sctp: %s", buffer);
}
#else
static void
SctpAliasLog(FILE *stream, const char *format, ...)
{
        va_list ap;

        va_start(ap, format);
        vfprintf(stream, format, ap);
        va_end(ap);
        fflush(stream);
}
#endif