/*      $OpenBSD: pptp.h,v 1.12 2024/02/26 08:29:37 yasuoka Exp $       */

/*-
 * Copyright (c) 2009 Internet Initiative Japan Inc.
 * All rights reserved.
 *
 * 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 AUTHOR 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 AUTHOR 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.
 */
#ifndef PPTP_H
#define PPTP_H  1

/*
 * PPTP protocol constants
 */
#define PPTP_MES_TYPE_CTRL                      1
#define PPTP_MAGIC_COOKIE                       0x1a2b3c4d
#define PPTP_RFC_2637_VERSION                   0x0100

#ifndef PPTP_MAX_CALL
#define PPTP_MAX_CALL                           8192
#endif

/* Start-Control-Connection-Request */
#define PPTP_CTRL_MES_CODE_SCCRQ        1

/* Start-Control-Connection-Reply */
#define PPTP_CTRL_MES_CODE_SCCRP        2

/* Stop-Control-Connection-Request */
#define PPTP_CTRL_MES_CODE_StopCCRQ     3

/* Stop-Control-Connection-Reply */
#define PPTP_CTRL_MES_CODE_StopCCRP     4

/* Echo-Request */
#define PPTP_CTRL_MES_CODE_ECHO_RQ      5

/* Echo-Reply */
#define PPTP_CTRL_MES_CODE_ECHO_RP      6

/* Outgoing-Call-Request */
#define PPTP_CTRL_MES_CODE_OCRQ         7

/* Outgoing-Call-Reply */
#define PPTP_CTRL_MES_CODE_OCRP         8

/* Incoming-Call-Request */
#define PPTP_CTRL_MES_CODE_ICRQ         9

/* Incoming-Call-Reply */
#define PPTP_CTRL_MES_CODE_ICRP         10

/* Incoming-Call-Connected */
#define PPTP_CTRL_MES_CODE_ICCN         11

/* Call-Clear-Request */
#define PPTP_CTRL_MES_CODE_CCR          12

/* Call-Disconnect-Notify */
#define PPTP_CTRL_MES_CODE_CDN          13

/* Set-Link-Info */
#define PPTP_CTRL_MES_CODE_SLI          15


#define PPTP_CTRL_FRAMING_ASYNC         1
#define PPTP_CTRL_FRAMING_SYNC          2

#define PPTP_CTRL_BEARER_ANALOG         1
#define PPTP_CTRL_BEARER_DIGITAL        2


/* Result Code: Start-Control-Connection-Reply */
#define PPTP_SCCRP_RESULT_SUCCESS               1
#define PPTP_SCCRP_RESULT_GENERIC_ERROR         2
#define PPTP_SCCRP_RESULT_CHANNEL_EXISTS        3
#define PPTP_SCCRP_RESULT_NOT_AUTHORIZIZED      4
#define PPTP_SCCRP_RESULT_BAD_PROTOCOL_VERSION  5

/* General Error Code (RFC 2637 2.16 pp.36) */
#define PPTP_ERROR_NONE                         0
#define PPTP_ERROR_NOT_CONNECTED                1
#define PPTP_ERROR_BAD_FORMAT                   2
#define PPTP_ERROR_NO_RESOURCE                  3
#define PPTP_ERROR_BAD_CALL                     4
#define PPTP_ERROR_PAC_ERROR                    5

/* Result Code: Outgoing-Call-Reply */
#define PPTP_OCRP_RESULT_CONNECTED              1
#define PPTP_OCRP_RESULT_GENERIC_ERROR          2
#define PPTP_OCRP_RESULT_NO_CARRIER             3
#define PPTP_OCRP_RESULT_BUSY                   4
#define PPTP_OCRP_RESULT_NO_DIALTONE            5
#define PPTP_OCRP_RESULT_TIMEOUT                6
#define PPTP_OCRP_RESULT_DO_NOT_ACCEPT          7

/* Result Code: Echo-Reply */
#define PPTP_ECHO_RP_RESULT_OK                  1
#define PPTP_ECHO_RP_RESULT_GENERIC_ERROR       2

/* Reason code of the Stop-Control-Connection-Request */
#define PPTP_StopCCRQ_REASON_NONE                       1
#define PPTP_StopCCRQ_REASON_STOP_PROTOCOL              2
#define PPTP_StopCCRQ_REASON_STOP_LOCAL_SHUTDOWN        3

/* Result code of the Stop-Control-Connection-Response */
#define PPTP_StopCCRP_RESULT_OK                 1
#define PPTP_StopCCRP_RESULT_GENERIC_ERROR      2

#define PPTP_CDN_RESULT_LOST_CARRIER            1
#define PPTP_CDN_RESULT_GENRIC_ERROR            2
#define PPTP_CDN_RESULT_ADMIN_SHUTDOWN          3
#define PPTP_CDN_RESULT_REQUEST                 4

/* Default TCP port number */
#define PPTPD_DEFAULT_TCP_PORT                  1723


#define PPTP_GRE_PROTOCOL_TYPE                  0x880b
#define PPTP_GRE_VERSION                        1

/*
 * Constants of the NPPPD implementation
 */
#include "pptp_conf.h"

/* pptpd status */
#define PPTPD_STATE_INIT                0
#define PPTPD_STATE_RUNNING             1
#define PPTPD_STATE_SHUTTING_DOWN       2
#define PPTPD_STATE_STOPPED             3

#define PPTPD_CONFIG_BUFSIZ             65535

#define PPTP_BACKLOG    32
#define PPTP_BUFSIZ     1024

#define PPTPD_DEFAULT_LAYER2_LABEL              "PPTP"

/* pptp control state code */
#define PPTP_CTRL_STATE_IDLE                    0
#define PPTP_CTRL_STATE_WAIT_CTRL_REPLY         1
#define PPTP_CTRL_STATE_ESTABLISHED             2
#define PPTP_CTRL_STATE_WAIT_STOP_REPLY         3
#define PPTP_CTRL_STATE_DISPOSING               4

#ifndef PPTPD_DEFAULT_VENDOR_NAME
#define PPTPD_DEFAULT_VENDOR_NAME               ""
#endif

#ifndef PPTP_CALL_DEFAULT_MAXWINSZ
#define PPTP_CALL_DEFAULT_MAXWINSZ              64
#endif

/* Connection speed that notified by OCRP */
/* XXX: currently we use fixed value */
#ifndef PPTP_CALL_CONNECT_SPEED
#define PPTP_CALL_CONNECT_SPEED                 10000000
#endif

/* Initial packet processing delay that notified by OCRP */
#ifndef PPTP_CALL_INITIAL_PPD
#define PPTP_CALL_INITIAL_PPD                   0
#endif

/**
 * PPTP_CALL_DELAY_LIMIT indicates how many sequence number can be rewinded
 * by reordering.
 */
#define PPTP_CALL_DELAY_LIMIT                   64

/* pptp call state machine */
#define PPTP_CALL_STATE_IDLE                    0
#define PPTP_CALL_STATE_WAIT_CONN               1
#define PPTP_CALL_STATE_ESTABLISHED             2
#define PPTP_CALL_STATE_CLEANUP_WAIT            3

/* Timeout */
#define PPTPD_SHUTDOWN_TIMEOUT                  5

#define PPTPD_IDLE_TIMEOUT                      60

#define PPTP_CALL_CLEANUP_WAIT_TIME             3

#define PPTP_CTRL_DEFAULT_ECHO_INTERVAL         60
#define PPTP_CTRL_DEFAULT_ECHO_TIMEOUT          60
#define PPTP_CTRL_StopCCRP_WAIT_TIME            3

/* MAXIMUM bindable IP addresses */
#ifndef PPTP_NLISTENER
#define PPTP_NLISTENER                          6
#endif

/* Utility macro */
#define pptpd_is_stopped(pptpd)                                 \
        (((pptpd)->state != PPTPD_STATE_SHUTTING_DOWN &&        \
            (pptpd)->state != PPTPD_STATE_RUNNING)? 1 : 0)

#define pptpd_is_shutting_down(pptpd)                           \
        (((pptpd)->state == PPTPD_STATE_SHUTTING_DOWN)? 1 : 0)

/*
 * types
 */
struct _pptpd;

typedef struct _pptpd_listener {
        struct event ev_sock_gre; /* GRE event context */
        struct _pptpd   *self;
        uint16_t        index;
        int             sock; /* listing socket */
        int             sock_gre; /* GRE socket */
        struct sockaddr_in bind_sin;    /* listing TCP address */
        struct sockaddr_in bind_sin_gre; /* listing GRE address */
        char    tun_name[PPTP_NAME_LEN];
        struct pptp_conf *conf;
} pptpd_listener;

typedef struct _pptpd {
        unsigned        id;
        slist listener;         /* list of listeners */
        int state;
        struct event ev_timer; /* timer event context */
        slist  ctrl_list;       /* list of PPTP controls */

        slist call_free_list;   /* Free call lists */
        hash_table *call_id_map; /* table to map between callid and call */
        /* ipv4 networks that is permitted to connect */

        uint32_t                /* flags */
            initialized:1;
} pptpd;

#define pptp_ctrl_sock_gre(ctrl)        \
        ((pptpd_listener *)slist_get(&(ctrl)->pptpd->listener,\
            (ctrl)->listener_index))->sock_gre

/* get listner's physical layer label from pptp_ctrl */
#define PPTP_CTRL_LISTENER_TUN_NAME(ctrl)       \
        ((pptpd_listener *)slist_get(&(ctrl)->pptpd->listener,\
            (ctrl)->listener_index))->tun_name

#define PPTP_CTRL_CONF(ctrl)                                    \
        ((pptpd_listener *)slist_get(&(ctrl)->pptpd->listener,  \
            (ctrl)->listener_index))->conf

typedef struct _pptp_ctrl {
        pptpd           *pptpd; /* parents */
        uint16_t        listener_index;
        unsigned        id;
        int             state;

        int             sock;
        struct sockaddr_storage peer;
        struct sockaddr_storage our;
        struct event    ev_sock;
        struct event    ev_timer;

        int echo_interval; /* periods between idle state to ECHO transmit */
        int echo_timeout;

        int             send_ready; /* ready to send */
        bytebuffer      *recv_buf;
        bytebuffer      *send_buf;

        slist           call_list;

        time_t  last_snd_ctrl;  /* timestamp of latest ctrl message sent */
        time_t  last_rcv_ctrl;  /* timestamp of latest ctrl message received */
        uint32_t        echo_seq; /* identifier of Echo Request */

        uint16_t        /* flags : processing I/O events */
                        on_io_event:1,
                        reserved:15;
} pptp_ctrl;

typedef struct _pptp_call {
        pptp_ctrl       *ctrl; /* parent */
        unsigned        id;

        int             ifidx; /* receive interface index */

        int             state;

        unsigned        peers_call_id;
        void            *ppp;

        uint32_t        snd_una;        /* next ack notification */
        uint32_t        snd_nxt;        /* next transmit sequence # */

        uint32_t        rcv_nxt;        /* received sequence # */
        uint32_t        rcv_acked;      /* latest acked received sequence # */

        int             winsz;          /* current window size */
        int             maxwinsz;       /* maximum window size */
        int             peers_maxwinsz;

        time_t          last_io;
} pptp_call;


/*
 * function prototypes
 */
#ifdef __cplusplus
extern "C" {
#endif

int   pptpd_init (pptpd *);
void  pptpd_uninit (pptpd *);
int   pptpd_assign_call (pptpd *, pptp_call *);
void  pptpd_release_call (pptpd *, pptp_call *);
int   pptpd_start (pptpd *);
void  pptpd_stop (pptpd *);
void pptpd_stop_immediatly (pptpd *);
void  pptpd_ctrl_finished_notify(pptpd *, pptp_ctrl *);
int  pptpd_add_listener(pptpd *, int, struct pptp_conf *, struct sockaddr *);

pptp_ctrl  *pptp_ctrl_create (void);
int        pptp_ctrl_init (pptp_ctrl *);
int        pptp_ctrl_start (pptp_ctrl *);
void       pptp_ctrl_stop (pptp_ctrl *, int);
void       pptp_ctrl_destroy (pptp_ctrl *);
void       pptp_ctrl_output (pptp_ctrl *, u_char *, int);

pptp_call  *pptp_call_create (void);
int        pptp_call_init (pptp_call *, pptp_ctrl *);
int        pptp_call_start (pptp_call *);
int        pptp_call_stop (pptp_call *);
void       pptp_call_destroy (pptp_call *);
void       pptp_call_input (pptp_call *, int, u_char *, int);
void       pptp_call_gre_input (pptp_call *, uint32_t, uint32_t, int, u_char *, int);
void       pptp_call_disconnect(pptp_call *, int, int, const char *);
int        pptpd_reload(pptpd *, struct pptp_confs *);

#ifdef __cplusplus
}
#endif
#endif