/*
 * Copyright (C) 2012 by Darren Reed.
 *
 * See the IPFILTER.LICENCE file for details on licencing.
 */
#if defined(KERNEL) || defined(_KERNEL)
# undef KERNEL
# undef _KERNEL
# define        KERNEL  1
# define        _KERNEL 1
#endif
#include <sys/errno.h>
#include <sys/types.h>
#include <sys/param.h>
#include <sys/file.h>
#if !defined(_KERNEL) && !defined(__KERNEL__)
# include <stdio.h>
# include <stdlib.h>
# include <string.h>
# define _KERNEL
# include <sys/uio.h>
# undef _KERNEL
#else
# include <sys/systm.h>
# if defined(NetBSD) && (__NetBSD_Version__ >= 104000000)
#  include <sys/proc.h>
# endif
#endif
#include <sys/time.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#if defined(_KERNEL) && !defined(__SVR4)
# include <sys/mbuf.h>
#endif
#if defined(__SVR4)
# include <sys/filio.h>
# include <sys/byteorder.h>
# ifdef _KERNEL
#  include <sys/dditypes.h>
# endif
# include <sys/stream.h>
# include <sys/kmem.h>
#endif
#if defined(__FreeBSD__)
# include <sys/malloc.h>
#endif

#include <net/if.h>
#include <netinet/in.h>

#include "netinet/ip_compat.h"
#include "netinet/ip_fil.h"
#include "netinet/ip_nat.h"
#include "netinet/ip_lookup.h"
#include "netinet/ip_dstlist.h"

/* END OF INCLUDES */

#ifdef HAS_SYS_MD5_H
# include <sys/md5.h>
#else
# include "md5.h"
#endif


typedef struct ipf_dstl_softc_s {
        ippool_dst_t    *dstlist[LOOKUP_POOL_SZ];
        ippool_dst_t    **tails[LOOKUP_POOL_SZ];
        ipf_dstl_stat_t stats;
} ipf_dstl_softc_t;


static void *ipf_dstlist_soft_create(ipf_main_softc_t *);
static void ipf_dstlist_soft_destroy(ipf_main_softc_t *, void *);
static int ipf_dstlist_soft_init(ipf_main_softc_t *, void *);
static void ipf_dstlist_soft_fini(ipf_main_softc_t *, void *);
static int ipf_dstlist_addr_find(ipf_main_softc_t *, void *, int,
                                      void *, u_int);
static size_t ipf_dstlist_flush(ipf_main_softc_t *, void *,
                                     iplookupflush_t *);
static int ipf_dstlist_iter_deref(ipf_main_softc_t *, void *, int, int,
                                       void *);
static int ipf_dstlist_iter_next(ipf_main_softc_t *, void *, ipftoken_t *,
                                      ipflookupiter_t *);
static int ipf_dstlist_node_add(ipf_main_softc_t *, void *,
                                     iplookupop_t *, int);
static int ipf_dstlist_node_del(ipf_main_softc_t *, void *,
                                     iplookupop_t *, int);
static int ipf_dstlist_stats_get(ipf_main_softc_t *, void *,
                                      iplookupop_t *);
static int ipf_dstlist_table_add(ipf_main_softc_t *, void *,
                                      iplookupop_t *);
static int ipf_dstlist_table_del(ipf_main_softc_t *, void *,
                                      iplookupop_t *);
static int ipf_dstlist_table_deref(ipf_main_softc_t *, void *, void *);
static void *ipf_dstlist_table_find(void *, int, char *);
static void ipf_dstlist_table_free(ipf_dstl_softc_t *, ippool_dst_t *);
static void ipf_dstlist_table_remove(ipf_main_softc_t *,
                                          ipf_dstl_softc_t *, ippool_dst_t *);
static void ipf_dstlist_table_clearnodes(ipf_dstl_softc_t *,
                                              ippool_dst_t *);
static ipf_dstnode_t *ipf_dstlist_select(fr_info_t *, ippool_dst_t *);
static void *ipf_dstlist_select_ref(void *, int, char *);
static void ipf_dstlist_node_free(ipf_dstl_softc_t *, ippool_dst_t *, ipf_dstnode_t *);
static int ipf_dstlist_node_deref(void *, ipf_dstnode_t *);
static void ipf_dstlist_expire(ipf_main_softc_t *, void *);
static void ipf_dstlist_sync(ipf_main_softc_t *, void *);

ipf_lookup_t ipf_dstlist_backend = {
        IPLT_DSTLIST,
        ipf_dstlist_soft_create,
        ipf_dstlist_soft_destroy,
        ipf_dstlist_soft_init,
        ipf_dstlist_soft_fini,
        ipf_dstlist_addr_find,
        ipf_dstlist_flush,
        ipf_dstlist_iter_deref,
        ipf_dstlist_iter_next,
        ipf_dstlist_node_add,
        ipf_dstlist_node_del,
        ipf_dstlist_stats_get,
        ipf_dstlist_table_add,
        ipf_dstlist_table_del,
        ipf_dstlist_table_deref,
        ipf_dstlist_table_find,
        ipf_dstlist_select_ref,
        ipf_dstlist_select_node,
        ipf_dstlist_expire,
        ipf_dstlist_sync
};


/* ------------------------------------------------------------------------ */
/* Function:    ipf_dstlist_soft_create                                     */
/* Returns:     int - 0 = success, else error                               */
/* Parameters:  softc(I) - pointer to soft context main structure           */
/*                                                                          */
/* Allocating a chunk of memory filled with 0's is enough for the current   */
/* soft context used with destination lists.                                */
/* ------------------------------------------------------------------------ */
static void *
ipf_dstlist_soft_create(ipf_main_softc_t *softc)
{
        ipf_dstl_softc_t *softd;
        int i;

        KMALLOC(softd, ipf_dstl_softc_t *);
        if (softd == NULL) {
                IPFERROR(120028);
                return (NULL);
        }

        bzero((char *)softd, sizeof(*softd));
        for (i = 0; i <= IPL_LOGMAX; i++)
                softd->tails[i] = &softd->dstlist[i];

        return (softd);
}


/* ------------------------------------------------------------------------ */
/* Function:    ipf_dstlist_soft_destroy                                    */
/* Returns:     Nil                                                         */
/* Parameters:  softc(I) - pointer to soft context main structure           */
/*              arg(I)   - pointer to local context to use                  */
/*                                                                          */
/* For destination lists, the only thing we have to do when destroying the  */
/* soft context is free it!                                                 */
/* ------------------------------------------------------------------------ */
static void
ipf_dstlist_soft_destroy(ipf_main_softc_t *softc, void *arg)
{
        ipf_dstl_softc_t *softd = arg;

        KFREE(softd);
}


/* ------------------------------------------------------------------------ */
/* Function:    ipf_dstlist_soft_init                                       */
/* Returns:     int - 0 = success, else error                               */
/* Parameters:  softc(I) - pointer to soft context main structure           */
/*              arg(I)   - pointer to local context to use                  */
/*                                                                          */
/* There is currently no soft context for destination list management.      */
/* ------------------------------------------------------------------------ */
static int
ipf_dstlist_soft_init(ipf_main_softc_t *softc, void *arg)
{
        return (0);
}


/* ------------------------------------------------------------------------ */
/* Function:    ipf_dstlist_soft_fini                                       */
/* Returns:     Nil                                                         */
/* Parameters:  softc(I) - pointer to soft context main structure           */
/*              arg(I)   - pointer to local context to use                  */
/*                                                                          */
/* There is currently no soft context for destination list management.      */
/* ------------------------------------------------------------------------ */
static void
ipf_dstlist_soft_fini(ipf_main_softc_t *softc, void *arg)
{
        ipf_dstl_softc_t *softd = arg;
        int i;

        for (i = -1; i <= IPL_LOGMAX; i++) {
                while (softd->dstlist[i + 1] != NULL) {
                        ipf_dstlist_table_remove(softc, softd,
                                                 softd->dstlist[i + 1]);
                }
        }

        ASSERT(softd->stats.ipls_numderefnodes == 0);
}


/* ------------------------------------------------------------------------ */
/* Function:    ipf_dstlist_addr_find                                       */
/* Returns:     int - 0 = success, else error                               */
/* Parameters:  softc(I) - pointer to soft context main structure           */
/*              arg1(I)  - pointer to local context to use                  */
/*              arg2(I)  - pointer to local context to use                  */
/*              arg3(I)  - pointer to local context to use                  */
/*              arg4(I)  - pointer to local context to use                  */
/*                                                                          */
/* There is currently no such thing as searching a destination list for an  */
/* address so this function becomes a no-op. Its presence is required as    */
/* ipf_lookup_res_name() stores the "addr_find" function pointer in the     */
/* pointer passed in to it as funcptr, although it could be a generic null- */
/* op function rather than a specific one.                                  */
/* ------------------------------------------------------------------------ */
/*ARGSUSED*/
static int
ipf_dstlist_addr_find(ipf_main_softc_t *softc, void *arg1, int arg2,
        void *arg3, u_int arg4)
{
        return (-1);
}


/* ------------------------------------------------------------------------ */
/* Function:    ipf_dstlist_flush                                           */
/* Returns:     int      - number of objects deleted                        */
/* Parameters:  softc(I) - pointer to soft context main structure           */
/*              arg(I)   - pointer to local context to use                  */
/*              fop(I)   - pointer to lookup flush operation data           */
/*                                                                          */
/* Flush all of the destination tables that match the data passed in with   */
/* the iplookupflush_t. There are two ways to match objects: the device for */
/* which they are to be used with and their name.                           */
/* ------------------------------------------------------------------------ */
static size_t
ipf_dstlist_flush(ipf_main_softc_t *softc, void *arg, iplookupflush_t *fop)
{
        ipf_dstl_softc_t *softd = arg;
        ippool_dst_t *node, *next;
        int n, i;

        for (n = 0, i = -1; i <= IPL_LOGMAX; i++) {
                if (fop->iplf_unit != IPLT_ALL && fop->iplf_unit != i)
                        continue;
                for (node = softd->dstlist[i + 1]; node != NULL; node = next) {
                        next = node->ipld_next;

                        if ((*fop->iplf_name != '\0') &&
                            strncmp(fop->iplf_name, node->ipld_name,
                                    FR_GROUPLEN))
                                continue;

                        ipf_dstlist_table_remove(softc, softd, node);
                        n++;
                }
        }
        return (n);
}


/* ------------------------------------------------------------------------ */
/* Function:    ipf_dstlist_iter_deref                                      */
/* Returns:     int      - 0 = success, else error                          */
/* Parameters:  softc(I) - pointer to soft context main structure           */
/*              arg(I)   - pointer to local context to use                  */
/*              otype(I) - type of data structure to iterate through        */
/*              unit(I)  - device we are working with                       */
/*              data(I)  - address of object in kernel space                */
/*                                                                          */
/* This function is called when the iteration token is being free'd and is  */
/* responsible for dropping the reference count of the structure it points  */
/* to.                                                                      */
/* ------------------------------------------------------------------------ */
static int
ipf_dstlist_iter_deref(ipf_main_softc_t *softc, void *arg, int otype,
        int unit, void *data)
{
        if (data == NULL) {
                IPFERROR(120001);
                return (EINVAL);
        }

        if (unit < -1 || unit > IPL_LOGMAX) {
                IPFERROR(120002);
                return (EINVAL);
        }

        switch (otype)
        {
        case IPFLOOKUPITER_LIST :
                ipf_dstlist_table_deref(softc, arg, (ippool_dst_t *)data);
                break;

        case IPFLOOKUPITER_NODE :
                ipf_dstlist_node_deref(arg, (ipf_dstnode_t *)data);
                break;
        }

        return (0);
}


/* ------------------------------------------------------------------------ */
/* Function:    ipf_dstlist_iter_next                                       */
/* Returns:     int - 0 = success, else error                               */
/* Parameters:  softc(I) - pointer to soft context main structure           */
/*              arg(I)   - pointer to local context to use                  */
/*              op(I)    - pointer to lookup operation data                 */
/*              uid(I)   - uid of process doing the ioctl                   */
/*                                                                          */
/* This function is responsible for either selecting the next destination   */
/* list or node on a destination list to be returned as a user process      */
/* iterates through the list of destination lists or nodes.                 */
/* ------------------------------------------------------------------------ */
static int
ipf_dstlist_iter_next(ipf_main_softc_t *softc, void *arg,
        ipftoken_t *token, ipflookupiter_t *iter)
{
        ipf_dstnode_t zn, *nextnode = NULL, *node = NULL;
        ippool_dst_t zero, *next = NULL, *dsttab = NULL;
        ipf_dstl_softc_t *softd = arg;
        int err = 0;
        void *hint;

        switch (iter->ili_otype)
        {
        case IPFLOOKUPITER_LIST :
                dsttab = token->ipt_data;
                if (dsttab == NULL) {
                        next = softd->dstlist[(int)iter->ili_unit + 1];
                } else {
                        next = dsttab->ipld_next;
                }

                if (next != NULL) {
                        ATOMIC_INC32(next->ipld_ref);
                        token->ipt_data = next;
                        hint = next->ipld_next;
                } else {
                        bzero((char *)&zero, sizeof(zero));
                        next = &zero;
                        token->ipt_data = NULL;
                        hint = NULL;
                }
                break;

        case IPFLOOKUPITER_NODE :
                node = token->ipt_data;
                if (node == NULL) {
                        dsttab = ipf_dstlist_table_find(arg, iter->ili_unit,
                                                        iter->ili_name);
                        if (dsttab == NULL) {
                                IPFERROR(120004);
                                err = ESRCH;
                                nextnode = NULL;
                        } else {
                                if (dsttab->ipld_dests == NULL)
                                        nextnode = NULL;
                                else
                                        nextnode = *dsttab->ipld_dests;
                                dsttab = NULL;
                        }
                } else {
                        nextnode = node->ipfd_next;
                }

                if (nextnode != NULL) {
                        MUTEX_ENTER(&nextnode->ipfd_lock);
                        nextnode->ipfd_ref++;
                        MUTEX_EXIT(&nextnode->ipfd_lock);
                        token->ipt_data = nextnode;
                        hint = nextnode->ipfd_next;
                } else {
                        bzero((char *)&zn, sizeof(zn));
                        nextnode = &zn;
                        token->ipt_data = NULL;
                        hint = NULL;
                }
                break;
        default :
                IPFERROR(120003);
                err = EINVAL;
                break;
        }

        if (err != 0)
                return (err);

        switch (iter->ili_otype)
        {
        case IPFLOOKUPITER_LIST :
                if (dsttab != NULL)
                        ipf_dstlist_table_deref(softc, arg, dsttab);
                err = COPYOUT(next, iter->ili_data, sizeof(*next));
                if (err != 0) {
                        IPFERROR(120005);
                        err = EFAULT;
                }
                break;

        case IPFLOOKUPITER_NODE :
                if (node != NULL)
                        ipf_dstlist_node_deref(arg, node);
                err = COPYOUT(nextnode, iter->ili_data, sizeof(*nextnode));
                if (err != 0) {
                        IPFERROR(120006);
                        err = EFAULT;
                }
                break;
        }

        if (hint == NULL)
                ipf_token_mark_complete(token);

        return (err);
}


/* ------------------------------------------------------------------------ */
/* Function:    ipf_dstlist_node_add                                        */
/* Returns:     int - 0 = success, else error                               */
/* Parameters:  softc(I) - pointer to soft context main structure           */
/*              arg(I)   - pointer to local context to use                  */
/*              op(I)    - pointer to lookup operation data                 */
/*              uid(I)   - uid of process doing the ioctl                   */
/* Locks:       WRITE(ipf_poolrw)                                           */
/*                                                                          */
/* Add a new node to a destination list. To do this, we only copy in the    */
/* frdest_t structure because that contains the only data required from the */
/* application to create a new node. The frdest_t doesn't contain the name  */
/* itself. When loading filter rules, fd_name is a 'pointer' to the name.   */
/* In this case, the 'pointer' does not work, instead it is the length of   */
/* the name and the name is immediately following the frdest_t structure.   */
/* fd_name must include the trailing \0, so it should be strlen(str) + 1.   */
/* For simple sanity checking, an upper bound on the size of fd_name is     */
/* imposed - 128.                                                          */
/* ------------------------------------------------------------------------ */
static int
ipf_dstlist_node_add(ipf_main_softc_t *softc, void *arg,
        iplookupop_t *op, int uid)
{
        ipf_dstl_softc_t *softd = arg;
        ipf_dstnode_t *node, **nodes;
        ippool_dst_t *d;
        frdest_t dest;
        int err;

        if (op->iplo_size < sizeof(frdest_t)) {
                IPFERROR(120007);
                return (EINVAL);
        }

        err = COPYIN(op->iplo_struct, &dest, sizeof(dest));
        if (err != 0) {
                IPFERROR(120009);
                return (EFAULT);
        }

        d = ipf_dstlist_table_find(arg, op->iplo_unit, op->iplo_name);
        if (d == NULL) {
                IPFERROR(120010);
                return (ESRCH);
        }

        switch (dest.fd_addr.adf_family)
        {
        case AF_INET :
        case AF_INET6 :
                break;
        default :
                IPFERROR(120019);
                return (EINVAL);
        }

        if (dest.fd_name < -1 || dest.fd_name > 128) {
                IPFERROR(120018);
                return (EINVAL);
        }

        KMALLOCS(node, ipf_dstnode_t *, sizeof(*node) + dest.fd_name);
        if (node == NULL) {
                softd->stats.ipls_nomem++;
                IPFERROR(120008);
                return (ENOMEM);
        }
        bzero((char *)node, sizeof(*node) + dest.fd_name);

        bcopy(&dest, &node->ipfd_dest, sizeof(dest));
        node->ipfd_size = sizeof(*node) + dest.fd_name;

        if (dest.fd_name > 0) {
                /*
                 * fd_name starts out as the length of the string to copy
                 * in (including \0) and ends up being the offset from
                 * fd_names (0).
                 */
                err = COPYIN((char *)op->iplo_struct + sizeof(dest),
                             node->ipfd_names, dest.fd_name);
                if (err != 0) {
                        IPFERROR(120017);
                        KFREES(node, node->ipfd_size);
                        return (EFAULT);
                }
                node->ipfd_dest.fd_name = 0;
        } else {
                node->ipfd_dest.fd_name = -1;
        }

        if (d->ipld_nodes == d->ipld_maxnodes) {
                KMALLOCS(nodes, ipf_dstnode_t **,
                         sizeof(*nodes) * (d->ipld_maxnodes + 1));
                if (nodes == NULL) {
                        softd->stats.ipls_nomem++;
                        IPFERROR(120022);
                        KFREES(node, node->ipfd_size);
                        return (ENOMEM);
                }
                if (d->ipld_dests != NULL) {
                        bcopy(d->ipld_dests, nodes,
                              sizeof(*nodes) * d->ipld_maxnodes);
                        KFREES(d->ipld_dests, sizeof(*nodes) * d->ipld_nodes);
                        nodes[0]->ipfd_pnext = nodes;
                }
                d->ipld_dests = nodes;
                d->ipld_maxnodes++;
        }
        d->ipld_dests[d->ipld_nodes] = node;
        d->ipld_nodes++;

        if (d->ipld_nodes == 1) {
                node->ipfd_pnext = d->ipld_dests;
        } else if (d->ipld_nodes > 1) {
                node->ipfd_pnext = &d->ipld_dests[d->ipld_nodes - 2]->ipfd_next;
        }
        *node->ipfd_pnext = node;

        MUTEX_INIT(&node->ipfd_lock, "ipf dst node lock");
        node->ipfd_uid = uid;
        node->ipfd_ref = 1;
        if (node->ipfd_dest.fd_name == 0)
                (void) ipf_resolvedest(softc, node->ipfd_names,
                                       &node->ipfd_dest, AF_INET);
#ifdef USE_INET6
        if (node->ipfd_dest.fd_name == 0 &&
            node->ipfd_dest.fd_ptr == (void *)-1)
                (void) ipf_resolvedest(softc, node->ipfd_names,
                                       &node->ipfd_dest, AF_INET6);
#endif

        softd->stats.ipls_numnodes++;

        return (0);
}


/* ------------------------------------------------------------------------ */
/* Function:    ipf_dstlist_node_deref                                      */
/* Returns:     int - 0 = success, else error                               */
/* Parameters:  arg(I)  - pointer to local context to use                   */
/*              node(I) - pointer to destionation node to free              */
/*                                                                          */
/* Dereference the use count by one. If it drops to zero then we can assume */
/* that it has been removed from any lists/tables and is ripe for freeing.  */
/* The pointer to context is required for the purpose of maintaining        */
/* statistics.                                                              */
/* ------------------------------------------------------------------------ */
static int
ipf_dstlist_node_deref(void *arg, ipf_dstnode_t *node)
{
        ipf_dstl_softc_t *softd = arg;
        int ref;

        MUTEX_ENTER(&node->ipfd_lock);
        ref = --node->ipfd_ref;
        MUTEX_EXIT(&node->ipfd_lock);

        if (ref > 0)
                return (0);

        if ((node->ipfd_flags & IPDST_DELETE) != 0)
                softd->stats.ipls_numderefnodes--;
        MUTEX_DESTROY(&node->ipfd_lock);
        KFREES(node, node->ipfd_size);
        softd->stats.ipls_numnodes--;

        return (0);
}


/* ------------------------------------------------------------------------ */
/* Function:    ipf_dstlist_node_del                                        */
/* Returns:     int      - 0 = success, else error                          */
/* Parameters:  softc(I) - pointer to soft context main structure           */
/*              arg(I)   - pointer to local context to use                  */
/*              op(I)    - pointer to lookup operation data                 */
/*              uid(I)   - uid of process doing the ioctl                   */
/*                                                                          */
/* Look for a matching destination node on the named table and free it if   */
/* found. Because the name embedded in the frdest_t is variable in length,  */
/* it is necessary to allocate some memory locally, to complete this op.    */
/* ------------------------------------------------------------------------ */
static int
ipf_dstlist_node_del(ipf_main_softc_t *softc, void *arg, iplookupop_t *op,
        int uid)
{
        ipf_dstl_softc_t *softd = arg;
        ipf_dstnode_t *node;
        frdest_t frd, *temp;
        ippool_dst_t *d;
        size_t size;
        int err;

        d = ipf_dstlist_table_find(arg, op->iplo_unit, op->iplo_name);
        if (d == NULL) {
                IPFERROR(120012);
                return (ESRCH);
        }

        err = COPYIN(op->iplo_struct, &frd, sizeof(frd));
        if (err != 0) {
                IPFERROR(120011);
                return (EFAULT);
        }

        size = sizeof(*temp) + frd.fd_name;
        KMALLOCS(temp, frdest_t *, size);
        if (temp == NULL) {
                softd->stats.ipls_nomem++;
                IPFERROR(120026);
                return (ENOMEM);
        }

        err = COPYIN(op->iplo_struct, temp, size);
        if (err != 0) {
                IPFERROR(120027);
                KFREES(temp, size);
                return (EFAULT);
        }

        MUTEX_ENTER(&d->ipld_lock);
        for (node = *d->ipld_dests; node != NULL; node = node->ipfd_next) {
                if ((uid != 0) && (node->ipfd_uid != uid))
                        continue;
                if (node->ipfd_size != size)
                        continue;
                if (!bcmp(&node->ipfd_dest.fd_ip6, &frd.fd_ip6,
                          size - offsetof(frdest_t, fd_ip6))) {
                        ipf_dstlist_node_free(softd, d, node);
                        MUTEX_EXIT(&d->ipld_lock);
                        KFREES(temp, size);
                        return (0);
                }
        }
        MUTEX_EXIT(&d->ipld_lock);
        KFREES(temp, size);

        return (ESRCH);
}


/* ------------------------------------------------------------------------ */
/* Function:    ipf_dstlist_node_free                                       */
/* Returns:     Nil                                                         */
/* Parameters:  softd(I) - pointer to the destination list context          */
/*              d(I)     - pointer to destination list                      */
/*              node(I)  - pointer to node to free                          */
/* Locks:       MUTEX(ipld_lock) or WRITE(ipf_poolrw)                       */
/*                                                                          */
/* Free the destination node by first removing it from any lists and then   */
/* checking if this was the last reference held to the object. While the    */
/* array of pointers to nodes is compacted, its size isn't reduced (by way  */
/* of allocating a new smaller one and copying) because the belief is that  */
/* it is likely the array will again reach that size.                       */
/* ------------------------------------------------------------------------ */
static void
ipf_dstlist_node_free(ipf_dstl_softc_t *softd, ippool_dst_t *d,
        ipf_dstnode_t *node)
{
        int i;

        /*
         * Compact the array of pointers to nodes.
         */
        for (i = 0; i < d->ipld_nodes; i++)
                if (d->ipld_dests[i] == node)
                        break;
        if (d->ipld_nodes - i > 1) {
                bcopy(&d->ipld_dests[i + 1], &d->ipld_dests[i],
                      sizeof(*d->ipld_dests) * (d->ipld_nodes - i - 1));
        }
        d->ipld_nodes--;

        if (node->ipfd_pnext != NULL)
                *node->ipfd_pnext = node->ipfd_next;
        if (node->ipfd_next != NULL)
                node->ipfd_next->ipfd_pnext = node->ipfd_pnext;
        node->ipfd_pnext = NULL;
        node->ipfd_next = NULL;

        if ((node->ipfd_flags & IPDST_DELETE) == 0) {
                softd->stats.ipls_numderefnodes++;
                node->ipfd_flags |= IPDST_DELETE;
        }

        ipf_dstlist_node_deref(softd, node);
}


/* ------------------------------------------------------------------------ */
/* Function:    ipf_dstlist_stats_get                                       */
/* Returns:     int - 0 = success, else error                               */
/* Parameters:  softc(I) - pointer to soft context main structure           */
/*              arg(I)   - pointer to local context to use                  */
/*              op(I)    - pointer to lookup operation data                 */
/*                                                                          */
/* Return the current statistics for destination lists. This may be for all */
/* of them or just information pertaining to a particular table.            */
/* ------------------------------------------------------------------------ */
/*ARGSUSED*/
static int
ipf_dstlist_stats_get(ipf_main_softc_t *softc, void *arg, iplookupop_t *op)
{
        ipf_dstl_softc_t *softd = arg;
        ipf_dstl_stat_t stats;
        int unit, i, err = 0;

        if (op->iplo_size != sizeof(ipf_dstl_stat_t)) {
                IPFERROR(120023);
                return (EINVAL);
        }

        stats = softd->stats;
        unit = op->iplo_unit;
        if (unit == IPL_LOGALL) {
                for (i = 0; i <= IPL_LOGMAX; i++)
                        stats.ipls_list[i] = softd->dstlist[i];
        } else if (unit >= 0 && unit <= IPL_LOGMAX) {
                void *ptr;

                if (op->iplo_name[0] != '\0')
                        ptr = ipf_dstlist_table_find(softd, unit,
                                                     op->iplo_name);
                else
                        ptr = softd->dstlist[unit + 1];
                stats.ipls_list[unit] = ptr;
        } else {
                IPFERROR(120024);
                err = EINVAL;
        }

        if (err == 0) {
                err = COPYOUT(&stats, op->iplo_struct, sizeof(stats));
                if (err != 0) {
                        IPFERROR(120025);
                        return (EFAULT);
                }
        }
        return (0);
}


/* ------------------------------------------------------------------------ */
/* Function:    ipf_dstlist_table_add                                       */
/* Returns:     int      - 0 = success, else error                          */
/* Parameters:  softc(I) - pointer to soft context main structure           */
/*              arg(I)   - pointer to local context to use                  */
/*              op(I)    - pointer to lookup operation data                 */
/*                                                                          */
/* Add a new destination table to the list of those available for the given */
/* device. Because we seldom operate on these objects (find/add/delete),    */
/* they are just kept in a simple linked list.                              */
/* ------------------------------------------------------------------------ */
static int
ipf_dstlist_table_add(ipf_main_softc_t *softc, void *arg, iplookupop_t *op)
{
        ipf_dstl_softc_t *softd = arg;
        ippool_dst_t user, *d, *new;
        int unit, err;

        d = ipf_dstlist_table_find(arg, op->iplo_unit, op->iplo_name);
        if (d != NULL) {
                IPFERROR(120013);
                return (EEXIST);
        }

        err = COPYIN(op->iplo_struct, &user, sizeof(user));
        if (err != 0) {
                IPFERROR(120021);
                return (EFAULT);
        }

        KMALLOC(new, ippool_dst_t *);
        if (new == NULL) {
                softd->stats.ipls_nomem++;
                IPFERROR(120014);
                return (ENOMEM);
        }
        bzero((char *)new, sizeof(*new));

        MUTEX_INIT(&new->ipld_lock, "ipf dst table lock");

        strncpy(new->ipld_name, op->iplo_name, FR_GROUPLEN);
        unit = op->iplo_unit;
        new->ipld_unit = unit;
        new->ipld_policy = user.ipld_policy;
        new->ipld_seed = ipf_random();
        new->ipld_ref = 1;

        new->ipld_pnext = softd->tails[unit + 1];
        *softd->tails[unit + 1] = new;
        softd->tails[unit + 1] = &new->ipld_next;
        softd->stats.ipls_numlists++;

        return (0);
}


/* ------------------------------------------------------------------------ */
/* Function:    ipf_dstlist_table_del                                       */
/* Returns:     int - 0 = success, else error                               */
/* Parameters:  softc(I) - pointer to soft context main structure           */
/*              arg(I)   - pointer to local context to use                  */
/*              op(I)    - pointer to lookup operation data                 */
/*                                                                          */
/* Find a named destinstion list table and delete it. If there are other    */
/* references to it, the caller isn't told.                                 */
/* ------------------------------------------------------------------------ */
static int
ipf_dstlist_table_del(ipf_main_softc_t *softc, void *arg, iplookupop_t *op)
{
        ippool_dst_t *d;

        d = ipf_dstlist_table_find(arg, op->iplo_unit, op->iplo_name);
        if (d == NULL) {
                IPFERROR(120015);
                return (ESRCH);
        }

        if (d->ipld_dests != NULL) {
                IPFERROR(120016);
                return (EBUSY);
        }

        ipf_dstlist_table_remove(softc, arg, d);

        return (0);
}


/* ------------------------------------------------------------------------ */
/* Function:    ipf_dstlist_table_remove                                    */
/* Returns:     Nil                                                         */
/* Parameters:  softc(I) - pointer to soft context main structure           */
/*              softd(I) - pointer to the destination list context          */
/*              d(I)     - pointer to destination list                      */
/*                                                                          */
/* Remove a given destination list from existence. While the IPDST_DELETE   */
/* flag is set every time we call this function and the reference count is  */
/* non-zero, the "numdereflists" counter is always incremented because the  */
/* decision about whether it will be freed or not is not made here. This    */
/* means that the only action the code can take here is to treat it as if   */
/* it will become a detached.                                               */
/* ------------------------------------------------------------------------ */
static void
ipf_dstlist_table_remove(ipf_main_softc_t *softc, ipf_dstl_softc_t *softd,
        ippool_dst_t *d)
{

        if (softd->tails[d->ipld_unit + 1] == &d->ipld_next)
                softd->tails[d->ipld_unit + 1] = d->ipld_pnext;

        if (d->ipld_pnext != NULL)
                *d->ipld_pnext = d->ipld_next;
        if (d->ipld_next != NULL)
                d->ipld_next->ipld_pnext = d->ipld_pnext;
        d->ipld_pnext = NULL;
        d->ipld_next = NULL;

        ipf_dstlist_table_clearnodes(softd, d);

        softd->stats.ipls_numdereflists++;
        d->ipld_flags |= IPDST_DELETE;

        ipf_dstlist_table_deref(softc, softd, d);
}


/* ------------------------------------------------------------------------ */
/* Function:    ipf_dstlist_table_free                                      */
/* Returns:     Nil                                                         */
/* Parameters:  softd(I) - pointer to the destination list context          */
/*              d(I)   - pointer to destination list                        */
/*                                                                          */
/* Free up a destination list data structure and any other memory that was  */
/* directly allocated as part of creating it. Individual destination list   */
/* nodes are not freed. It is assumed the caller will have already emptied  */
/* the destination list.                                                    */
/* ------------------------------------------------------------------------ */
static void
ipf_dstlist_table_free(ipf_dstl_softc_t *softd, ippool_dst_t *d)
{
        MUTEX_DESTROY(&d->ipld_lock);

        if ((d->ipld_flags & IPDST_DELETE) != 0)
                softd->stats.ipls_numdereflists--;
        softd->stats.ipls_numlists--;

        if (d->ipld_dests != NULL) {
                KFREES(d->ipld_dests,
                       d->ipld_maxnodes * sizeof(*d->ipld_dests));
        }

        KFREE(d);
}


/* ------------------------------------------------------------------------ */
/* Function:    ipf_dstlist_table_deref                                     */
/* Returns:     int - 0 = success, else error                               */
/* Parameters:  softc(I) - pointer to soft context main structure           */
/*              arg(I)   - pointer to local context to use                  */
/*              op(I)    - pointer to lookup operation data                 */
/*                                                                          */
/* Drops the reference count on a destination list table object and free's  */
/* it if 0 has been reached.                                                */
/* ------------------------------------------------------------------------ */
static int
ipf_dstlist_table_deref(ipf_main_softc_t *softc, void *arg, void *table)
{
        ippool_dst_t *d = table;

        d->ipld_ref--;
        if (d->ipld_ref > 0)
                return (d->ipld_ref);

        ipf_dstlist_table_free(arg, d);

        return (0);
}


/* ------------------------------------------------------------------------ */
/* Function:    ipf_dstlist_table_clearnodes                                */
/* Returns:     Nil                                                         */
/* Parameters:  softd(I) - pointer to the destination list context          */
/*              dst(I)   - pointer to destination list                      */
/*                                                                          */
/* Free all of the destination nodes attached to the given table.           */
/* ------------------------------------------------------------------------ */
static void
ipf_dstlist_table_clearnodes(ipf_dstl_softc_t *softd, ippool_dst_t *dst)
{
        ipf_dstnode_t *node;

        if (dst->ipld_dests == NULL)
                return;

        while ((node = *dst->ipld_dests) != NULL) {
                ipf_dstlist_node_free(softd, dst, node);
        }
}


/* ------------------------------------------------------------------------ */
/* Function:    ipf_dstlist_table_find                                      */
/* Returns:     int      - 0 = success, else error                          */
/* Parameters:  arg(I)   - pointer to local context to use                  */
/*              unit(I)  - device we are working with                       */
/*              name(I)  - destination table name to find                   */
/*                                                                          */
/* Return a pointer to a destination table that matches the unit+name that  */
/* is passed in.                                                            */
/* ------------------------------------------------------------------------ */
static void *
ipf_dstlist_table_find(void *arg, int unit, char *name)
{
        ipf_dstl_softc_t *softd = arg;
        ippool_dst_t *d;

        for (d = softd->dstlist[unit + 1]; d != NULL; d = d->ipld_next) {
                if ((d->ipld_unit == unit) &&
                    !strncmp(d->ipld_name, name, FR_GROUPLEN)) {
                        return (d);
                }
        }

        return (NULL);
}


/* ------------------------------------------------------------------------ */
/* Function:    ipf_dstlist_select_ref                                      */
/* Returns:     void *   - NULL = failure, else pointer to table            */
/* Parameters:  arg(I)   - pointer to local context to use                  */
/*              unit(I)  - device we are working with                       */
/*              name(I)  - destination table name to find                   */
/*                                                                          */
/* Attempt to find a destination table that matches the name passed in and  */
/* if successful, bump up the reference count on it because we intend to    */
/* store the pointer to it somewhere else.                                  */
/* ------------------------------------------------------------------------ */
static void *
ipf_dstlist_select_ref(void *arg, int unit, char *name)
{
        ippool_dst_t *d;

        d = ipf_dstlist_table_find(arg, unit, name);
        if (d != NULL) {
                MUTEX_ENTER(&d->ipld_lock);
                d->ipld_ref++;
                MUTEX_EXIT(&d->ipld_lock);
        }
        return (d);
}


/* ------------------------------------------------------------------------ */
/* Function:    ipf_dstlist_select                                          */
/* Returns:     void * - NULL = failure, else pointer to table              */
/* Parameters:  fin(I) - pointer to packet information                      */
/*              d(I)   - pointer to destination list                        */
/*                                                                          */
/* Find the next node in the destination list to be used according to the   */
/* defined policy. Of these, "connection" is the most expensive policy to   */
/* implement as it always looks for the node with the least number of       */
/* connections associated with it.                                          */
/*                                                                          */
/* The hashes exclude the port numbers so that all protocols map to the     */
/* same destination. Otherwise, someone doing a ping would target a         */
/* different server than their TCP connection, etc. MD-5 is used to         */
/* transform the addressese into something random that the other end could  */
/* not easily guess and use in an attack. ipld_seed introduces an unknown   */
/* into the hash calculation to increase the difficult of an attacker       */
/* guessing the bucket.                                                     */
/*                                                                          */
/* One final comment: mixing different address families in a single pool    */
/* will currently result in failures as the address family of the node is   */
/* only matched up with that in the packet as the last step. While this can */
/* be coded around for the weighted connection and round-robin models, it   */
/* cannot be supported for the hash/random models as they do not search and */
/* nor is the algorithm conducive to searching.                             */
/* ------------------------------------------------------------------------ */
static ipf_dstnode_t *
ipf_dstlist_select(fr_info_t *fin, ippool_dst_t *d)
{
        ipf_dstnode_t *node, *sel;
        int connects;
        u_32_t hash[4];
        MD5_CTX ctx;
        int family;
        int x;

        if (d == NULL || d->ipld_dests == NULL || *d->ipld_dests == NULL)
                return (NULL);

        family = fin->fin_family;

        MUTEX_ENTER(&d->ipld_lock);

        switch (d->ipld_policy)
        {
        case IPLDP_ROUNDROBIN:
                sel = d->ipld_selected;
                if (sel == NULL) {
                        sel = *d->ipld_dests;
                } else {
                        sel = sel->ipfd_next;
                        if (sel == NULL)
                                sel = *d->ipld_dests;
                }
                break;

        case IPLDP_CONNECTION:
                if (d->ipld_selected == NULL) {
                        sel = *d->ipld_dests;
                        break;
                }

                sel = d->ipld_selected;
                connects = 0x7fffffff;
                node = sel->ipfd_next;
                if (node == NULL)
                        node = *d->ipld_dests;
                while (node != d->ipld_selected) {
                        if (node->ipfd_states == 0) {
                                sel = node;
                                break;
                        }
                        if (node->ipfd_states < connects) {
                                sel = node;
                                connects = node->ipfd_states;
                        }
                        node = node->ipfd_next;
                        if (node == NULL)
                                node = *d->ipld_dests;
                }
                break;

        case IPLDP_RANDOM :
                x = ipf_random() % d->ipld_nodes;
                sel = d->ipld_dests[x];
                break;

        case IPLDP_HASHED :
                MD5Init(&ctx);
                MD5Update(&ctx, (u_char *)&d->ipld_seed, sizeof(d->ipld_seed));
                MD5Update(&ctx, (u_char *)&fin->fin_src6,
                          sizeof(fin->fin_src6));
                MD5Update(&ctx, (u_char *)&fin->fin_dst6,
                          sizeof(fin->fin_dst6));
                MD5Final((u_char *)hash, &ctx);
                x = ntohl(hash[0]) % d->ipld_nodes;
                sel = d->ipld_dests[x];
                break;

        case IPLDP_SRCHASH :
                MD5Init(&ctx);
                MD5Update(&ctx, (u_char *)&d->ipld_seed, sizeof(d->ipld_seed));
                MD5Update(&ctx, (u_char *)&fin->fin_src6,
                          sizeof(fin->fin_src6));
                MD5Final((u_char *)hash, &ctx);
                x = ntohl(hash[0]) % d->ipld_nodes;
                sel = d->ipld_dests[x];
                break;

        case IPLDP_DSTHASH :
                MD5Init(&ctx);
                MD5Update(&ctx, (u_char *)&d->ipld_seed, sizeof(d->ipld_seed));
                MD5Update(&ctx, (u_char *)&fin->fin_dst6,
                          sizeof(fin->fin_dst6));
                MD5Final((u_char *)hash, &ctx);
                x = ntohl(hash[0]) % d->ipld_nodes;
                sel = d->ipld_dests[x];
                break;

        default :
                sel = NULL;
                break;
        }

        if (sel && sel->ipfd_dest.fd_addr.adf_family != family)
                sel = NULL;
        d->ipld_selected = sel;

        MUTEX_EXIT(&d->ipld_lock);

        return (sel);
}


/* ------------------------------------------------------------------------ */
/* Function:    ipf_dstlist_select_node                                     */
/* Returns:     int      - -1 == failure, 0 == success                      */
/* Parameters:  fin(I)   - pointer to packet information                    */
/*              group(I) - destination pool to search                       */
/*              addr(I)  - pointer to store selected address                */
/*              pfdp(O)  - pointer to storage for selected destination node */
/*                                                                          */
/* This function is only responsible for obtaining the next IP address for  */
/* use and storing it in the caller's address space (addr). "addr" is only  */
/* used for storage if pfdp is NULL. No permanent reference is currently    */
/* kept on the node.                                                        */
/* ------------------------------------------------------------------------ */
int
ipf_dstlist_select_node(fr_info_t *fin, void *group, u_32_t *addr,
        frdest_t *pfdp)
{
#ifdef USE_MUTEXES
        ipf_main_softc_t *softc = fin->fin_main_soft;
#endif
        ippool_dst_t *d = group;
        ipf_dstnode_t *node;
        frdest_t *fdp;

        READ_ENTER(&softc->ipf_poolrw);

        node = ipf_dstlist_select(fin, d);
        if (node == NULL) {
                RWLOCK_EXIT(&softc->ipf_poolrw);
                return (-1);
        }

        if (pfdp != NULL) {
                bcopy(&node->ipfd_dest, pfdp, sizeof(*pfdp));
        } else {
                if (fin->fin_family == AF_INET) {
                        addr[0] = node->ipfd_dest.fd_addr.adf_addr.i6[0];
                } else if (fin->fin_family == AF_INET6) {
                        addr[0] = node->ipfd_dest.fd_addr.adf_addr.i6[0];
                        addr[1] = node->ipfd_dest.fd_addr.adf_addr.i6[1];
                        addr[2] = node->ipfd_dest.fd_addr.adf_addr.i6[2];
                        addr[3] = node->ipfd_dest.fd_addr.adf_addr.i6[3];
                }
        }

        fdp = &node->ipfd_dest;
        if (fdp->fd_ptr == NULL)
                fdp->fd_ptr = fin->fin_ifp;

        MUTEX_ENTER(&node->ipfd_lock);
        node->ipfd_states++;
        MUTEX_EXIT(&node->ipfd_lock);

        RWLOCK_EXIT(&softc->ipf_poolrw);

        return (0);
}


/* ------------------------------------------------------------------------ */
/* Function:    ipf_dstlist_expire                                          */
/* Returns:     Nil                                                         */
/* Parameters:  softc(I) - pointer to soft context main structure           */
/*              arg(I)   - pointer to local context to use                  */
/*                                                                          */
/* There are currently no objects to expire in destination lists.           */
/* ------------------------------------------------------------------------ */
static void
ipf_dstlist_expire(ipf_main_softc_t *softc, void *arg)
{
        return;
}


/* ------------------------------------------------------------------------ */
/* Function:    ipf_dstlist_sync                                            */
/* Returns:     Nil                                                         */
/* Parameters:  softc(I) - pointer to soft context main structure           */
/*              arg(I)   - pointer to local context to use                  */
/*                                                                          */
/* When a network interface appears or disappears, we need to revalidate    */
/* all of the network interface names that have been configured as a target */
/* in a destination list.                                                   */
/* ------------------------------------------------------------------------ */
void
ipf_dstlist_sync(ipf_main_softc_t *softc, void *arg)
{
        ipf_dstl_softc_t *softd = arg;
        ipf_dstnode_t *node;
        ippool_dst_t *list;
        int i;
        int j;

        for (i = 0; i < IPL_LOGMAX; i++) {
                for (list = softd->dstlist[i]; list != NULL;
                     list = list->ipld_next) {
                        for (j = 0; j < list->ipld_maxnodes; j++) {
                                node = list->ipld_dests[j];
                                if (node == NULL)
                                        continue;
                                if (node->ipfd_dest.fd_name == -1)
                                        continue;
                                (void) ipf_resolvedest(softc,
                                                       node->ipfd_names,
                                                       &node->ipfd_dest,
                                                       AF_INET);
                        }
                }
        }
}