/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright 2005, Gleb Smirnoff <glebius@FreeBSD.org>
 * 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.
 */

#include "opt_inet.h"
#include "opt_inet6.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mbuf.h>
#include <sys/malloc.h>
#include <sys/ctype.h>
#include <sys/errno.h>
#include <sys/rwlock.h>
#include <sys/socket.h>
#include <sys/syslog.h>

#include <net/if.h>
#include <net/if_var.h>

#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/in_var.h>
#include <netinet/ip_var.h>
#include <netinet/ip_fw.h>
#include <netinet/ip.h>
#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>

#include <netpfil/ipfw/ip_fw_private.h>

#include <netgraph/ng_message.h>
#include <netgraph/ng_parse.h>
#include <netgraph/ng_ipfw.h>
#include <netgraph/netgraph.h>

static int              ng_ipfw_mod_event(module_t mod, int event, void *data);
static ng_constructor_t ng_ipfw_constructor;
static ng_shutdown_t    ng_ipfw_shutdown;
static ng_newhook_t     ng_ipfw_newhook;
static ng_connect_t     ng_ipfw_connect;
static ng_findhook_t    ng_ipfw_findhook;
static ng_rcvdata_t     ng_ipfw_rcvdata;
static ng_disconnect_t  ng_ipfw_disconnect;

static hook_p           ng_ipfw_findhook1(node_p, uint32_t );
static int      ng_ipfw_input(struct mbuf **, struct ip_fw_args *, bool);

/* We have only one node */
static node_p   fw_node;

/* Netgraph node type descriptor */
static struct ng_type ng_ipfw_typestruct = {
        .version =      NG_ABI_VERSION,
        .name =         NG_IPFW_NODE_TYPE,
        .mod_event =    ng_ipfw_mod_event,
        .constructor =  ng_ipfw_constructor,
        .shutdown =     ng_ipfw_shutdown,
        .newhook =      ng_ipfw_newhook,
        .connect =      ng_ipfw_connect,
        .findhook =     ng_ipfw_findhook,
        .rcvdata =      ng_ipfw_rcvdata,
        .disconnect =   ng_ipfw_disconnect,
};
NETGRAPH_INIT(ipfw, &ng_ipfw_typestruct);
MODULE_DEPEND(ng_ipfw, ipfw, 3, 3, 3);

/* Information we store for each hook */
struct ng_ipfw_hook_priv {
        hook_p          hook;
        uint32_t        cookie;
};
typedef struct ng_ipfw_hook_priv *hpriv_p;

static int
ng_ipfw_mod_event(module_t mod, int event, void *data)
{
        int error = 0;

        switch (event) {
        case MOD_LOAD:

                if (ng_ipfw_input_p != NULL) {
                        error = EEXIST;
                        break;
                }

                /* Setup node without any private data */
                if ((error = ng_make_node_common(&ng_ipfw_typestruct, &fw_node))
                    != 0) {
                        log(LOG_ERR, "%s: can't create ng_ipfw node", __func__);
                        break;
                }

                /* Try to name node */
                if (ng_name_node(fw_node, "ipfw") != 0)
                        log(LOG_WARNING, "%s: failed to name node \"ipfw\"",
                            __func__);

                /* Register hook */
                ng_ipfw_input_p = ng_ipfw_input;
                break;

        case MOD_UNLOAD:
                 /*
                  * This won't happen if a node exists.
                  * ng_ipfw_input_p is already cleared.
                  */
                break;

        default:
                error = EOPNOTSUPP;
                break;
        }

        return (error);
}

static int
ng_ipfw_constructor(node_p node)
{
        return (EINVAL);        /* Only one node */
}

static int
ng_ipfw_newhook(node_p node, hook_p hook, const char *name)
{
        hpriv_p hpriv;
        uint32_t cookie;
        const char *cp;
        char *endptr;

        /* Protect from leading zero */
        if (name[0] == '0' && name[1] != '\0')
                return (EINVAL);

        /* Check that name contains only digits */
        for (cp = name; *cp != '\0'; cp++)
                if (!isdigit(*cp))
                        return (EINVAL);

        /* Convert it to integer */
        cookie = (uint32_t)strtoul(name, &endptr, 10);
        if (*endptr != '\0')
                return (EINVAL);

        /* Allocate memory for this hook's private data */
        hpriv = malloc(sizeof(*hpriv), M_NETGRAPH, M_NOWAIT | M_ZERO);
        if (hpriv== NULL)
                return (ENOMEM);

        hpriv->hook = hook;
        hpriv->cookie = cookie;

        NG_HOOK_SET_PRIVATE(hook, hpriv);

        return(0);
}

/*
 * Set hooks into queueing mode, to avoid recursion between
 * netgraph layer and ip_{input,output}.
 */
static int
ng_ipfw_connect(hook_p hook)
{
        NG_HOOK_FORCE_QUEUE(hook);
        return (0);
}

/* Look up hook by name */
static hook_p
ng_ipfw_findhook(node_p node, const char *name)
{
        uint32_t n;     /* numeric representation of hook */
        char *endptr;

        n = (uint32_t)strtoul(name, &endptr, 10);
        if (*endptr != '\0')
                return NULL;
        return ng_ipfw_findhook1(node, n);
}

/* Look up hook by rule number */
static hook_p
ng_ipfw_findhook1(node_p node, uint32_t cookie)
{
        hook_p  hook;
        hpriv_p hpriv;

        LIST_FOREACH(hook, &node->nd_hooks, hk_hooks) {
                hpriv = NG_HOOK_PRIVATE(hook);
                if (NG_HOOK_IS_VALID(hook) && (hpriv->cookie == cookie))
                        return (hook);
        }

        return (NULL);
}

static int
ng_ipfw_rcvdata(hook_p hook, item_p item)
{
        struct m_tag *tag;
        struct ipfw_rule_ref *r;
        struct mbuf *m;
        struct ip *ip;

        NGI_GET_M(item, m);
        NG_FREE_ITEM(item);

        tag = m_tag_locate(m, MTAG_IPFW_RULE, 0, NULL);
        if (tag == NULL) {
                NG_FREE_M(m);
                return (EINVAL);        /* XXX: find smth better */
        }

        if (m->m_len < sizeof(struct ip) &&
            (m = m_pullup(m, sizeof(struct ip))) == NULL)
                return (ENOBUFS);

        ip = mtod(m, struct ip *);

        r = (struct ipfw_rule_ref *)(tag + 1);
        if (r->info & IPFW_INFO_IN) {
                switch (ip->ip_v) {
#ifdef INET
                case IPVERSION:
                        ip_input(m);
                        return (0);
#endif
#ifdef INET6
                case IPV6_VERSION >> 4:
                        ip6_input(m);
                        return (0);
#endif
                }
        } else {
                switch (ip->ip_v) {
#ifdef INET
                case IPVERSION:
                        return (ip_output(m, NULL, NULL, IP_FORWARDING,
                            NULL, NULL));
#endif
#ifdef INET6
                case IPV6_VERSION >> 4:
                        return (ip6_output(m, NULL, NULL, 0, NULL,
                            NULL, NULL));
#endif
                }
        }

        /* unknown IP protocol version */
        NG_FREE_M(m);
        return (EPROTONOSUPPORT);
}

static int
ng_ipfw_input(struct mbuf **m0, struct ip_fw_args *fwa, bool tee)
{
        struct mbuf *m;
        hook_p  hook;
        int error = 0;

        /*
         * Node must be loaded and corresponding hook must be present.
         */
        if (fw_node == NULL || 
           (hook = ng_ipfw_findhook1(fw_node, fwa->rule.info & IPFW_INFO_MASK)) == NULL)
                return (ESRCH);         /* no hook associated with this rule */

        /*
         * We have two modes: in normal mode we add a tag to packet, which is
         * important to return packet back to IP stack. In tee mode we make
         * a copy of a packet and forward it into netgraph without a tag.
         */
        if (tee == false) {
                struct m_tag *tag;
                struct ipfw_rule_ref *r;
                m = *m0;
                *m0 = NULL;     /* it belongs now to netgraph */

                tag = m_tag_alloc(MTAG_IPFW_RULE, 0, sizeof(*r),
                        M_NOWAIT|M_ZERO);
                if (tag == NULL) {
                        m_freem(m);
                        return (ENOMEM);
                }
                r = (struct ipfw_rule_ref *)(tag + 1);
                *r = fwa->rule;
                r->info &= IPFW_ONEPASS;  /* keep this info */
                r->info |= (fwa->flags & IPFW_ARGS_IN) ?
                    IPFW_INFO_IN : IPFW_INFO_OUT;
                m_tag_prepend(m, tag);

        } else
                if ((m = m_dup(*m0, M_NOWAIT)) == NULL)
                        return (ENOMEM);        /* which is ignored */

        if (m->m_len < sizeof(struct ip) &&
            (m = m_pullup(m, sizeof(struct ip))) == NULL)
                return (EINVAL);

        NG_SEND_DATA_ONLY(error, hook, m);

        return (error);
}

static int
ng_ipfw_shutdown(node_p node)
{

        /*
         * After our single node has been removed,
         * the only thing that can be done is
         * 'kldunload ng_ipfw.ko'
         */
        ng_ipfw_input_p = NULL;
        NG_NODE_UNREF(node);
        return (0);
}

static int
ng_ipfw_disconnect(hook_p hook)
{
        const hpriv_p hpriv = NG_HOOK_PRIVATE(hook);

        free(hpriv, M_NETGRAPH);
        NG_HOOK_SET_PRIVATE(hook, NULL);

        return (0);
}