/*-
 * 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.
 *
 * $FreeBSD: src/sys/netgraph/ng_ipfw.c,v 1.9 2006/02/14 15:22:24 ru Exp $
 */

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

#include <net/if.h>

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

#include "ng_message.h"
#include "ng_parse.h"
#include "ng_ipfw.h"
#include "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, u_int16_t );
static int              ng_ipfw_input(struct mbuf **, int, struct ip_fw_args *,
                            int);

/* 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, 2, 2, 2);

/* Information we store for each hook */
struct ng_ipfw_hook_priv {
        hook_p          hook;
        u_int16_t       rulenum;
};
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;
        u_int16_t rulenum;
        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 */
        rulenum = (u_int16_t)strtol(name, &endptr, 10);
        if (*endptr != '\0')
                return (EINVAL);

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

        hpriv->hook = hook;
        hpriv->rulenum = rulenum;

        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 */
hook_p
ng_ipfw_findhook(node_p node, const char *name)
{
        u_int16_t n;    /* numeric representation of hook */
        char *endptr;

        n = (u_int16_t)strtol(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, u_int16_t rulenum)
{
        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->rulenum == rulenum))
                        return (hook);
        }

        return (NULL);
}


static int
ng_ipfw_rcvdata(hook_p hook, item_p item)
{
        struct ng_ipfw_tag      *ngit;
        struct mbuf *m;

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

        if ((ngit = (struct ng_ipfw_tag *)m_tag_locate(m, NGM_IPFW_COOKIE, 0,
            NULL)) == NULL) {
                NG_FREE_M(m);
                return (EINVAL);        /* XXX: find smth better */
        }

        switch (ngit->dir) {
        case NG_IPFW_OUT:
            {
                struct ip *ip;

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

                ip = mtod(m, struct ip *);

                return ip_output(m, NULL, NULL, IP_FORWARDING, NULL, NULL);
            }
        case NG_IPFW_IN:
                ip_input(m);
                return (0);
        default:
                panic("ng_ipfw_rcvdata: bad dir %u", ngit->dir);
        }       

        /* not reached */
        return (0);
}

static int
ng_ipfw_input(struct mbuf **m0, int dir, struct ip_fw_args *fwa, int tee)
{
        struct mbuf *m;
        struct ng_ipfw_tag *ngit;
        struct ip *ip;
        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->cookie)) == NULL) {
                if (tee == 0)
                        m_freem(*m0);
                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 == 0) {
                m = *m0;
                *m0 = NULL;     /* it belongs now to netgraph */

                if ((ngit = (struct ng_ipfw_tag *)m_tag_alloc(NGM_IPFW_COOKIE,
                    0, TAGSIZ, M_NOWAIT)) == NULL) {
                        m_freem(m);
                        return (ENOMEM);
                }
                ngit->rule = fwa->rule;
                ngit->dir = dir;
                ngit->ifp = fwa->oif;
                m_tag_prepend(m, &ngit->mt);

        } 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);

        ip = mtod(m, struct ip *);

        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);

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

        return (0);
}