Parallelize ifnet.if_addrhead accessing by duplicating the list itself

[dragonfly.git] / sys / net / ipfw / ip_fw2.c

/*
 * Copyright (c) 2002 Luigi Rizzo, Universita` di Pisa
 *
 * 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/netinet/ip_fw2.c,v 1.6.2.12 2003/04/08 10:42:32 maxim Exp $
 * $DragonFly: src/sys/net/ipfw/ip_fw2.c,v 1.41 2008/03/07 11:34:20 sephe Exp $
 */

#define        DEB(x)
#define        DDB(x) x

/*
 * Implement IP packet firewall (new version)
 */

#ifndef KLD_MODULE
#include "opt_ipfw.h"
#include "opt_ipdn.h"
#include "opt_ipdivert.h"
#include "opt_inet.h"
#ifndef INET
#error IPFIREWALL requires INET.
#endif /* INET */
#endif

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/sysctl.h>
#include <sys/syslog.h>
#include <sys/thread2.h>
#include <sys/ucred.h>
#include <sys/in_cksum.h>
#include <net/if.h>
#include <net/route.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/in_var.h>
#include <netinet/in_pcb.h>
#include <netinet/ip.h>
#include <netinet/ip_var.h>
#include <netinet/ip_icmp.h>
#include "ip_fw.h"
#include <net/dummynet/ip_dummynet.h>
#include <netinet/tcp.h>
#include <netinet/tcp_timer.h>
#include <netinet/tcp_var.h>
#include <netinet/tcpip.h>
#include <netinet/udp.h>
#include <netinet/udp_var.h>

#include <netinet/if_ether.h> /* XXX for ETHERTYPE_IP */

/*
 * set_disable contains one bit per set value (0..31).
 * If the bit is set, all rules with the corresponding set
 * are disabled. Set 31 is reserved for the default rule
 * and CANNOT be disabled.
 */
static uint32_t set_disable;

static int fw_verbose;
static int verbose_limit;

#ifdef KLD_MODULE
static int ipfw_refcnt;
#endif

static struct callout ipfw_timeout_h;
#define IPFW_DEFAULT_RULE       65535

/*
 * list of rules for layer 3
 */
static struct ip_fw *layer3_chain;

MALLOC_DEFINE(M_IPFW, "IpFw/IpAcct", "IpFw/IpAcct chain's");

static int fw_debug = 1;
static int autoinc_step = 100; /* bounded to 1..1000 in ipfw_add_rule() */

#ifdef SYSCTL_NODE
SYSCTL_NODE(_net_inet_ip, OID_AUTO, fw, CTLFLAG_RW, 0, "Firewall");
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, enable, CTLFLAG_RW,
    &fw_enable, 0, "Enable ipfw");
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, autoinc_step, CTLFLAG_RW,
    &autoinc_step, 0, "Rule number autincrement step");
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO,one_pass,CTLFLAG_RW,
    &fw_one_pass, 0,
    "Only do a single pass through ipfw when using dummynet(4)");
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, debug, CTLFLAG_RW,
    &fw_debug, 0, "Enable printing of debug ip_fw statements");
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, verbose, CTLFLAG_RW,
    &fw_verbose, 0, "Log matches to ipfw rules");
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, verbose_limit, CTLFLAG_RW,
    &verbose_limit, 0, "Set upper limit of matches of ipfw rules logged");

/*
 * Description of dynamic rules.
 *
 * Dynamic rules are stored in lists accessed through a hash table
 * (ipfw_dyn_v) whose size is curr_dyn_buckets. This value can
 * be modified through the sysctl variable dyn_buckets which is
 * updated when the table becomes empty.
 *
 * XXX currently there is only one list, ipfw_dyn.
 *
 * When a packet is received, its address fields are first masked
 * with the mask defined for the rule, then hashed, then matched
 * against the entries in the corresponding list.
 * Dynamic rules can be used for different purposes:
 *  + stateful rules;
 *  + enforcing limits on the number of sessions;
 *  + in-kernel NAT (not implemented yet)
 *
 * The lifetime of dynamic rules is regulated by dyn_*_lifetime,
 * measured in seconds and depending on the flags.
 *
 * The total number of dynamic rules is stored in dyn_count.
 * The max number of dynamic rules is dyn_max. When we reach
 * the maximum number of rules we do not create anymore. This is
 * done to avoid consuming too much memory, but also too much
 * time when searching on each packet (ideally, we should try instead
 * to put a limit on the length of the list on each bucket...).
 *
 * Each dynamic rule holds a pointer to the parent ipfw rule so
 * we know what action to perform. Dynamic rules are removed when
 * the parent rule is deleted. XXX we should make them survive.
 *
 * There are some limitations with dynamic rules -- we do not
 * obey the 'randomized match', and we do not do multiple
 * passes through the firewall. XXX check the latter!!!
 */
static ipfw_dyn_rule **ipfw_dyn_v = NULL;
static uint32_t dyn_buckets = 256; /* must be power of 2 */
static uint32_t curr_dyn_buckets = 256; /* must be power of 2 */

/*
 * Timeouts for various events in handing dynamic rules.
 */
static uint32_t dyn_ack_lifetime = 300;
static uint32_t dyn_syn_lifetime = 20;
static uint32_t dyn_fin_lifetime = 1;
static uint32_t dyn_rst_lifetime = 1;
static uint32_t dyn_udp_lifetime = 10;
static uint32_t dyn_short_lifetime = 5;

/*
 * Keepalives are sent if dyn_keepalive is set. They are sent every
 * dyn_keepalive_period seconds, in the last dyn_keepalive_interval
 * seconds of lifetime of a rule.
 * dyn_rst_lifetime and dyn_fin_lifetime should be strictly lower
 * than dyn_keepalive_period.
 */

static uint32_t dyn_keepalive_interval = 20;
static uint32_t dyn_keepalive_period = 5;
static uint32_t dyn_keepalive = 1;      /* do send keepalives */

static uint32_t static_count;           /* # of static rules */
static uint32_t static_ioc_len; /* bytes of static rules */
static uint32_t dyn_count;              /* # of dynamic rules */
static uint32_t dyn_max = 4096; /* max # of dynamic rules */

SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_buckets, CTLFLAG_RW,
    &dyn_buckets, 0, "Number of dyn. buckets");
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, curr_dyn_buckets, CTLFLAG_RD,
    &curr_dyn_buckets, 0, "Current Number of dyn. buckets");
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_count, CTLFLAG_RD,
    &dyn_count, 0, "Number of dyn. rules");
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_max, CTLFLAG_RW,
    &dyn_max, 0, "Max number of dyn. rules");
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, static_count, CTLFLAG_RD,
    &static_count, 0, "Number of static rules");
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_ack_lifetime, CTLFLAG_RW,
    &dyn_ack_lifetime, 0, "Lifetime of dyn. rules for acks");
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_syn_lifetime, CTLFLAG_RW,
    &dyn_syn_lifetime, 0, "Lifetime of dyn. rules for syn");
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_fin_lifetime, CTLFLAG_RW,
    &dyn_fin_lifetime, 0, "Lifetime of dyn. rules for fin");
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_rst_lifetime, CTLFLAG_RW,
    &dyn_rst_lifetime, 0, "Lifetime of dyn. rules for rst");
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_udp_lifetime, CTLFLAG_RW,
    &dyn_udp_lifetime, 0, "Lifetime of dyn. rules for UDP");
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_short_lifetime, CTLFLAG_RW,
    &dyn_short_lifetime, 0, "Lifetime of dyn. rules for other situations");
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_keepalive, CTLFLAG_RW,
    &dyn_keepalive, 0, "Enable keepalives for dyn. rules");

#endif /* SYSCTL_NODE */

/**
 * dummynet needs a reference to the default rule, because rules can be
 * deleted while packets hold a reference to them. When this happens,
 * dummynet changes the reference to the default rule (it could well be a
 * NULL pointer, but this way we do not need to check for the special
 * case, plus here he have info on the default behaviour).
 */
struct ip_fw *ip_fw_default_rule;

static ip_fw_chk_t      ipfw_chk;

static __inline int
ipfw_free_rule(struct ip_fw *rule)
{
        KASSERT(rule->refcnt > 0, ("invalid refcnt %u\n", rule->refcnt));
        atomic_subtract_int(&rule->refcnt, 1);
        if (atomic_cmpset_int(&rule->refcnt, 0, 1)) {
                kfree(rule, M_IPFW);
                return 1;
        }
        return 0;
}

static void
ipfw_unref_rule(void *priv)
{
        ipfw_free_rule(priv);
#ifdef KLD_MODULE
        atomic_subtract_int(&ipfw_refcnt, 1);
#endif
}

static __inline void
ipfw_ref_rule(struct ip_fw *rule)
{
#ifdef KLD_MODULE
        atomic_add_int(&ipfw_refcnt, 1);
#endif
        atomic_add_int(&rule->refcnt, 1);
}

/*
 * This macro maps an ip pointer into a layer3 header pointer of type T
 */
#define L3HDR(T, ip) ((T *)((uint32_t *)(ip) + (ip)->ip_hl))

static __inline int
icmptype_match(struct ip *ip, ipfw_insn_u32 *cmd)
{
        int type = L3HDR(struct icmp,ip)->icmp_type;

        return (type <= ICMP_MAXTYPE && (cmd->d[0] & (1<<type)) );
}

#define TT      ( (1 << ICMP_ECHO) | (1 << ICMP_ROUTERSOLICIT) | \
    (1 << ICMP_TSTAMP) | (1 << ICMP_IREQ) | (1 << ICMP_MASKREQ) )

static int
is_icmp_query(struct ip *ip)
{
        int type = L3HDR(struct icmp, ip)->icmp_type;
        return (type <= ICMP_MAXTYPE && (TT & (1<<type)) );
}
#undef TT

/*
 * The following checks use two arrays of 8 or 16 bits to store the
 * bits that we want set or clear, respectively. They are in the
 * low and high half of cmd->arg1 or cmd->d[0].
 *
 * We scan options and store the bits we find set. We succeed if
 *
 *      (want_set & ~bits) == 0 && (want_clear & ~bits) == want_clear
 *
 * The code is sometimes optimized not to store additional variables.
 */

static int
flags_match(ipfw_insn *cmd, uint8_t bits)
{
        u_char want_clear;
        bits = ~bits;

        if ( ((cmd->arg1 & 0xff) & bits) != 0)
                return 0; /* some bits we want set were clear */
        want_clear = (cmd->arg1 >> 8) & 0xff;
        if ( (want_clear & bits) != want_clear)
                return 0; /* some bits we want clear were set */
        return 1;
}

static int
ipopts_match(struct ip *ip, ipfw_insn *cmd)
{
        int optlen, bits = 0;
        u_char *cp = (u_char *)(ip + 1);
        int x = (ip->ip_hl << 2) - sizeof (struct ip);

        for (; x > 0; x -= optlen, cp += optlen) {
                int opt = cp[IPOPT_OPTVAL];

                if (opt == IPOPT_EOL)
                        break;
                if (opt == IPOPT_NOP)
                        optlen = 1;
                else {
                        optlen = cp[IPOPT_OLEN];
                        if (optlen <= 0 || optlen > x)
                                return 0; /* invalid or truncated */
                }
                switch (opt) {

                default:
                        break;

                case IPOPT_LSRR:
                        bits |= IP_FW_IPOPT_LSRR;
                        break;

                case IPOPT_SSRR:
                        bits |= IP_FW_IPOPT_SSRR;
                        break;

                case IPOPT_RR:
                        bits |= IP_FW_IPOPT_RR;
                        break;

                case IPOPT_TS:
                        bits |= IP_FW_IPOPT_TS;
                        break;
                }
        }
        return (flags_match(cmd, bits));
}

static int
tcpopts_match(struct ip *ip, ipfw_insn *cmd)
{
        int optlen, bits = 0;
        struct tcphdr *tcp = L3HDR(struct tcphdr,ip);
        u_char *cp = (u_char *)(tcp + 1);
        int x = (tcp->th_off << 2) - sizeof(struct tcphdr);

        for (; x > 0; x -= optlen, cp += optlen) {
                int opt = cp[0];
                if (opt == TCPOPT_EOL)
                        break;
                if (opt == TCPOPT_NOP)
                        optlen = 1;
                else {
                        optlen = cp[1];
                        if (optlen <= 0)
                                break;
                }

                switch (opt) {

                default:
                        break;

                case TCPOPT_MAXSEG:
                        bits |= IP_FW_TCPOPT_MSS;
                        break;

                case TCPOPT_WINDOW:
                        bits |= IP_FW_TCPOPT_WINDOW;
                        break;

                case TCPOPT_SACK_PERMITTED:
                case TCPOPT_SACK:
                        bits |= IP_FW_TCPOPT_SACK;
                        break;

                case TCPOPT_TIMESTAMP:
                        bits |= IP_FW_TCPOPT_TS;
                        break;

                case TCPOPT_CC:
                case TCPOPT_CCNEW:
                case TCPOPT_CCECHO:
                        bits |= IP_FW_TCPOPT_CC;
                        break;
                }
        }
        return (flags_match(cmd, bits));
}

static int
iface_match(struct ifnet *ifp, ipfw_insn_if *cmd)
{
        if (ifp == NULL)        /* no iface with this packet, match fails */
                return 0;
        /* Check by name or by IP address */
        if (cmd->name[0] != '\0') { /* match by name */
                /* Check name */
                if (cmd->p.glob) {
                        if (kfnmatch(cmd->name, ifp->if_xname, 0) == 0)
                                return(1);
                } else {
                        if (strncmp(ifp->if_xname, cmd->name, IFNAMSIZ) == 0)
                                return(1);
                }
        } else {
                struct ifaddr_container *ifac;

                TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) {
                        struct ifaddr *ia = ifac->ifa;

                        if (ia->ifa_addr == NULL)
                                continue;
                        if (ia->ifa_addr->sa_family != AF_INET)
                                continue;
                        if (cmd->p.ip.s_addr == ((struct sockaddr_in *)
                            (ia->ifa_addr))->sin_addr.s_addr)
                                return(1);      /* match */
                }
        }
        return(0);      /* no match, fail ... */
}

static uint64_t norule_counter; /* counter for ipfw_log(NULL...) */

#define SNPARGS(buf, len) buf + len, sizeof(buf) > len ? sizeof(buf) - len : 0
#define SNP(buf) buf, sizeof(buf)

/*
 * We enter here when we have a rule with O_LOG.
 * XXX this function alone takes about 2Kbytes of code!
 */
static void
ipfw_log(struct ip_fw *f, u_int hlen, struct ether_header *eh,
        struct mbuf *m, struct ifnet *oif)
{
        char *action;
        int limit_reached = 0;
        char action2[40], proto[48], fragment[28];

        fragment[0] = '\0';
        proto[0] = '\0';

        if (f == NULL) {        /* bogus pkt */
                if (verbose_limit != 0 && norule_counter >= verbose_limit)
                        return;
                norule_counter++;
                if (norule_counter == verbose_limit)
                        limit_reached = verbose_limit;
                action = "Refuse";
        } else {        /* O_LOG is the first action, find the real one */
                ipfw_insn *cmd = ACTION_PTR(f);
                ipfw_insn_log *l = (ipfw_insn_log *)cmd;

                if (l->max_log != 0 && l->log_left == 0)
                        return;
                l->log_left--;
                if (l->log_left == 0)
                        limit_reached = l->max_log;
                cmd += F_LEN(cmd);      /* point to first action */
                if (cmd->opcode == O_PROB)
                        cmd += F_LEN(cmd);

                action = action2;
                switch (cmd->opcode) {
                case O_DENY:
                        action = "Deny";
                        break;

                case O_REJECT:
                        if (cmd->arg1==ICMP_REJECT_RST)
                                action = "Reset";
                        else if (cmd->arg1==ICMP_UNREACH_HOST)
                                action = "Reject";
                        else
                                ksnprintf(SNPARGS(action2, 0), "Unreach %d",
                                        cmd->arg1);
                        break;

                case O_ACCEPT:
                        action = "Accept";
                        break;
                case O_COUNT:
                        action = "Count";
                        break;
                case O_DIVERT:
                        ksnprintf(SNPARGS(action2, 0), "Divert %d",
                                cmd->arg1);
                        break;
                case O_TEE:
                        ksnprintf(SNPARGS(action2, 0), "Tee %d",
                                cmd->arg1);
                        break;
                case O_SKIPTO:
                        ksnprintf(SNPARGS(action2, 0), "SkipTo %d",
                                cmd->arg1);
                        break;
                case O_PIPE:
                        ksnprintf(SNPARGS(action2, 0), "Pipe %d",
                                cmd->arg1);
                        break;
                case O_QUEUE:
                        ksnprintf(SNPARGS(action2, 0), "Queue %d",
                                cmd->arg1);
                        break;
                case O_FORWARD_IP: {
                        ipfw_insn_sa *sa = (ipfw_insn_sa *)cmd;
                        int len;

                        len = ksnprintf(SNPARGS(action2, 0), "Forward to %s",
                                inet_ntoa(sa->sa.sin_addr));
                        if (sa->sa.sin_port)
                                ksnprintf(SNPARGS(action2, len), ":%d",
                                    sa->sa.sin_port);
                        }
                        break;
                default:
                        action = "UNKNOWN";
                        break;
                }
        }

        if (hlen == 0) {        /* non-ip */
                ksnprintf(SNPARGS(proto, 0), "MAC");
        } else {
                struct ip *ip = mtod(m, struct ip *);
                /* these three are all aliases to the same thing */
                struct icmp *const icmp = L3HDR(struct icmp, ip);
                struct tcphdr *const tcp = (struct tcphdr *)icmp;
                struct udphdr *const udp = (struct udphdr *)icmp;

                int ip_off, offset, ip_len;

                int len;

                if (eh != NULL) { /* layer 2 packets are as on the wire */
                        ip_off = ntohs(ip->ip_off);
                        ip_len = ntohs(ip->ip_len);
                } else {
                        ip_off = ip->ip_off;
                        ip_len = ip->ip_len;
                }
                offset = ip_off & IP_OFFMASK;
                switch (ip->ip_p) {
                case IPPROTO_TCP:
                        len = ksnprintf(SNPARGS(proto, 0), "TCP %s",
                            inet_ntoa(ip->ip_src));
                        if (offset == 0)
                                ksnprintf(SNPARGS(proto, len), ":%d %s:%d",
                                    ntohs(tcp->th_sport),
                                    inet_ntoa(ip->ip_dst),
                                    ntohs(tcp->th_dport));
                        else
                                ksnprintf(SNPARGS(proto, len), " %s",
                                    inet_ntoa(ip->ip_dst));
                        break;

                case IPPROTO_UDP:
                        len = ksnprintf(SNPARGS(proto, 0), "UDP %s",
                                inet_ntoa(ip->ip_src));
                        if (offset == 0)
                                ksnprintf(SNPARGS(proto, len), ":%d %s:%d",
                                    ntohs(udp->uh_sport),
                                    inet_ntoa(ip->ip_dst),
                                    ntohs(udp->uh_dport));
                        else
                                ksnprintf(SNPARGS(proto, len), " %s",
                                    inet_ntoa(ip->ip_dst));
                        break;

                case IPPROTO_ICMP:
                        if (offset == 0)
                                len = ksnprintf(SNPARGS(proto, 0),
                                    "ICMP:%u.%u ",
                                    icmp->icmp_type, icmp->icmp_code);
                        else
                                len = ksnprintf(SNPARGS(proto, 0), "ICMP ");
                        len += ksnprintf(SNPARGS(proto, len), "%s",
                            inet_ntoa(ip->ip_src));
                        ksnprintf(SNPARGS(proto, len), " %s",
                            inet_ntoa(ip->ip_dst));
                        break;

                default:
                        len = ksnprintf(SNPARGS(proto, 0), "P:%d %s", ip->ip_p,
                            inet_ntoa(ip->ip_src));
                        ksnprintf(SNPARGS(proto, len), " %s",
                            inet_ntoa(ip->ip_dst));
                        break;
                }

                if (ip_off & (IP_MF | IP_OFFMASK))
                        ksnprintf(SNPARGS(fragment, 0), " (frag %d:%d@%d%s)",
                             ntohs(ip->ip_id), ip_len - (ip->ip_hl << 2),
                             offset << 3,
                             (ip_off & IP_MF) ? "+" : "");
        }
        if (oif || m->m_pkthdr.rcvif)
                log(LOG_SECURITY | LOG_INFO,
                    "ipfw: %d %s %s %s via %s%s\n",
                    f ? f->rulenum : -1,
                    action, proto, oif ? "out" : "in",
                    oif ? oif->if_xname : m->m_pkthdr.rcvif->if_xname,
                    fragment);
        else
                log(LOG_SECURITY | LOG_INFO,
                    "ipfw: %d %s %s [no if info]%s\n",
                    f ? f->rulenum : -1,
                    action, proto, fragment);
        if (limit_reached)
                log(LOG_SECURITY | LOG_NOTICE,
                    "ipfw: limit %d reached on entry %d\n",
                    limit_reached, f ? f->rulenum : -1);
}

/*
 * IMPORTANT: the hash function for dynamic rules must be commutative
 * in source and destination (ip,port), because rules are bidirectional
 * and we want to find both in the same bucket.
 */
static __inline int
hash_packet(struct ipfw_flow_id *id)
{
        uint32_t i;

        i = (id->dst_ip) ^ (id->src_ip) ^ (id->dst_port) ^ (id->src_port);
        i &= (curr_dyn_buckets - 1);
        return i;
}

/**
 * unlink a dynamic rule from a chain. prev is a pointer to
 * the previous one, q is a pointer to the rule to delete,
 * head is a pointer to the head of the queue.
 * Modifies q and potentially also head.
 */
#define UNLINK_DYN_RULE(prev, head, q) {                                \
        ipfw_dyn_rule *old_q = q;                                       \
                                                                        \
        /* remove a refcount to the parent */                           \
        if (q->dyn_type == O_LIMIT)                                     \
                q->parent->count--;                                     \
        DEB(kprintf("-- unlink entry 0x%08x %d -> 0x%08x %d, %d left\n",        \
                (q->id.src_ip), (q->id.src_port),                       \
                (q->id.dst_ip), (q->id.dst_port), dyn_count-1 ); )      \
        if (prev != NULL)                                               \
                prev->next = q = q->next;                               \
        else                                                            \
                head = q = q->next;                                     \
        KASSERT(dyn_count > 0, ("invalid dyn count %u\n", dyn_count));  \
        dyn_count--;                                                    \
        kfree(old_q, M_IPFW); }

#define TIME_LEQ(a,b)       ((int)((a)-(b)) <= 0)

/**
 * Remove dynamic rules pointing to "rule", or all of them if rule == NULL.
 *
 * If keep_me == NULL, rules are deleted even if not expired,
 * otherwise only expired rules are removed.
 *
 * The value of the second parameter is also used to point to identify
 * a rule we absolutely do not want to remove (e.g. because we are
 * holding a reference to it -- this is the case with O_LIMIT_PARENT
 * rules). The pointer is only used for comparison, so any non-null
 * value will do.
 */
static void
remove_dyn_rule(struct ip_fw *rule, ipfw_dyn_rule *keep_me)
{
        static uint32_t last_remove = 0;

#define FORCE (keep_me == NULL)

        ipfw_dyn_rule *prev, *q;
        int i, pass = 0, max_pass = 0;

        if (ipfw_dyn_v == NULL || dyn_count == 0)
                return;
        /* do not expire more than once per second, it is useless */
        if (!FORCE && last_remove == time_second)
                return;
        last_remove = time_second;

        /*
         * because O_LIMIT refer to parent rules, during the first pass only
         * remove child and mark any pending LIMIT_PARENT, and remove
         * them in a second pass.
         */
next_pass:
        for (i = 0 ; i < curr_dyn_buckets ; i++) {
                for (prev=NULL, q = ipfw_dyn_v[i] ; q ; ) {
                        /*
                         * Logic can become complex here, so we split tests.
                         */
                        if (q == keep_me)
                                goto next;
                        if (rule != NULL && rule != q->rule)
                                goto next; /* not the one we are looking for */
                        if (q->dyn_type == O_LIMIT_PARENT) {
                                /*
                                 * handle parent in the second pass,
                                 * record we need one.
                                 */
                                max_pass = 1;
                                if (pass == 0)
                                        goto next;
                                if (FORCE && q->count != 0 ) {
                                        /* XXX should not happen! */
                                        kprintf( "OUCH! cannot remove rule,"
                                             " count %d\n", q->count);
                                }
                        } else {
                                if (!FORCE &&
                                    !TIME_LEQ( q->expire, time_second ))
                                        goto next;
                        }
                        UNLINK_DYN_RULE(prev, ipfw_dyn_v[i], q);
                        continue;
next:
                        prev=q;
                        q=q->next;
                }
        }
        if (pass++ < max_pass)
                goto next_pass;
}


/**
 * lookup a dynamic rule.
 */
static ipfw_dyn_rule *
lookup_dyn_rule(struct ipfw_flow_id *pkt, int *match_direction,
        struct tcphdr *tcp)
{
        /*
         * stateful ipfw extensions.
         * Lookup into dynamic session queue
         */
#define MATCH_REVERSE   0
#define MATCH_FORWARD   1
#define MATCH_NONE      2
#define MATCH_UNKNOWN   3
        int i, dir = MATCH_NONE;
        ipfw_dyn_rule *prev, *q=NULL;

        if (ipfw_dyn_v == NULL)
                goto done;      /* not found */
        i = hash_packet( pkt );
        for (prev=NULL, q = ipfw_dyn_v[i] ; q != NULL ; ) {
                if (q->dyn_type == O_LIMIT_PARENT)
                        goto next;
                if (TIME_LEQ( q->expire, time_second)) { /* expire entry */
                        UNLINK_DYN_RULE(prev, ipfw_dyn_v[i], q);
                        continue;
                }
                if ( pkt->proto == q->id.proto) {
                        if (pkt->src_ip == q->id.src_ip &&
                            pkt->dst_ip == q->id.dst_ip &&
                            pkt->src_port == q->id.src_port &&
                            pkt->dst_port == q->id.dst_port ) {
                                dir = MATCH_FORWARD;
                                break;
                        }
                        if (pkt->src_ip == q->id.dst_ip &&
                            pkt->dst_ip == q->id.src_ip &&
                            pkt->src_port == q->id.dst_port &&
                            pkt->dst_port == q->id.src_port ) {
                                dir = MATCH_REVERSE;
                                break;
                        }
                }
next:
                prev = q;
                q = q->next;
        }
        if (q == NULL)
                goto done; /* q = NULL, not found */

        if ( prev != NULL) { /* found and not in front */
                prev->next = q->next;
                q->next = ipfw_dyn_v[i];
                ipfw_dyn_v[i] = q;
        }
        if (pkt->proto == IPPROTO_TCP) { /* update state according to flags */
                u_char flags = pkt->flags & (TH_FIN|TH_SYN|TH_RST);

#define BOTH_SYN        (TH_SYN | (TH_SYN << 8))
#define BOTH_FIN        (TH_FIN | (TH_FIN << 8))
                q->state |= (dir == MATCH_FORWARD ) ? flags : (flags << 8);
                switch (q->state) {
                case TH_SYN:                            /* opening */
                        q->expire = time_second + dyn_syn_lifetime;
                        break;

                case BOTH_SYN:                  /* move to established */
                case BOTH_SYN | TH_FIN :        /* one side tries to close */
                case BOTH_SYN | (TH_FIN << 8) :
                        if (tcp) {
#define _SEQ_GE(a,b) ((int)(a) - (int)(b) >= 0)
                            uint32_t ack = ntohl(tcp->th_ack);
                            if (dir == MATCH_FORWARD) {
                                if (q->ack_fwd == 0 || _SEQ_GE(ack, q->ack_fwd))
                                    q->ack_fwd = ack;
                                else { /* ignore out-of-sequence */
                                    break;
                                }
                            } else {
                                if (q->ack_rev == 0 || _SEQ_GE(ack, q->ack_rev))
                                    q->ack_rev = ack;
                                else { /* ignore out-of-sequence */
                                    break;
                                }
                            }
                        }
                        q->expire = time_second + dyn_ack_lifetime;
                        break;

                case BOTH_SYN | BOTH_FIN:       /* both sides closed */
                        if (dyn_fin_lifetime >= dyn_keepalive_period)
                                dyn_fin_lifetime = dyn_keepalive_period - 1;
                        q->expire = time_second + dyn_fin_lifetime;
                        break;

                default:
#if 0
                        /*
                         * reset or some invalid combination, but can also
                         * occur if we use keep-state the wrong way.
                         */
                        if ( (q->state & ((TH_RST << 8)|TH_RST)) == 0)
                                kprintf("invalid state: 0x%x\n", q->state);
#endif
                        if (dyn_rst_lifetime >= dyn_keepalive_period)
                                dyn_rst_lifetime = dyn_keepalive_period - 1;
                        q->expire = time_second + dyn_rst_lifetime;
                        break;
                }
        } else if (pkt->proto == IPPROTO_UDP) {
                q->expire = time_second + dyn_udp_lifetime;
        } else {
                /* other protocols */
                q->expire = time_second + dyn_short_lifetime;
        }
done:
        if (match_direction)
                *match_direction = dir;
        return q;
}

static void
realloc_dynamic_table(void)
{
        /*
         * Try reallocation, make sure we have a power of 2 and do
         * not allow more than 64k entries. In case of overflow,
         * default to 1024.
         */

        if (dyn_buckets > 65536)
                dyn_buckets = 1024;
        if ((dyn_buckets & (dyn_buckets-1)) != 0) { /* not a power of 2 */
                dyn_buckets = curr_dyn_buckets; /* reset */
                return;
        }
        curr_dyn_buckets = dyn_buckets;
        if (ipfw_dyn_v != NULL)
                kfree(ipfw_dyn_v, M_IPFW);
        for (;;) {
                ipfw_dyn_v = kmalloc(curr_dyn_buckets * sizeof(ipfw_dyn_rule *),
                       M_IPFW, M_INTWAIT | M_NULLOK | M_ZERO);
                if (ipfw_dyn_v != NULL || curr_dyn_buckets <= 2)
                        break;
                curr_dyn_buckets /= 2;
        }
}

/**
 * Install state of type 'type' for a dynamic session.
 * The hash table contains two type of rules:
 * - regular rules (O_KEEP_STATE)
 * - rules for sessions with limited number of sess per user
 *   (O_LIMIT). When they are created, the parent is
 *   increased by 1, and decreased on delete. In this case,
 *   the third parameter is the parent rule and not the chain.
 * - "parent" rules for the above (O_LIMIT_PARENT).
 */
static ipfw_dyn_rule *
add_dyn_rule(struct ipfw_flow_id *id, uint8_t dyn_type, struct ip_fw *rule)
{
        ipfw_dyn_rule *r;
        int i;

        if (ipfw_dyn_v == NULL ||
            (dyn_count == 0 && dyn_buckets != curr_dyn_buckets)) {
                realloc_dynamic_table();
                if (ipfw_dyn_v == NULL)
                        return NULL; /* failed ! */
        }
        i = hash_packet(id);

        r = kmalloc(sizeof *r, M_IPFW, M_INTWAIT | M_NULLOK | M_ZERO);
        if (r == NULL) {
                kprintf ("sorry cannot allocate state\n");
                return NULL;
        }

        /* increase refcount on parent, and set pointer */
        if (dyn_type == O_LIMIT) {
                ipfw_dyn_rule *parent = (ipfw_dyn_rule *)rule;
                if ( parent->dyn_type != O_LIMIT_PARENT)
                        panic("invalid parent");
                parent->count++;
                r->parent = parent;
                rule = parent->rule;
        }

        r->id = *id;
        r->expire = time_second + dyn_syn_lifetime;
        r->rule = rule;
        r->dyn_type = dyn_type;
        r->pcnt = r->bcnt = 0;
        r->count = 0;

        r->bucket = i;
        r->next = ipfw_dyn_v[i];
        ipfw_dyn_v[i] = r;
        dyn_count++;
        DEB(kprintf("-- add dyn entry ty %d 0x%08x %d -> 0x%08x %d, total %d\n",
           dyn_type,
           (r->id.src_ip), (r->id.src_port),
           (r->id.dst_ip), (r->id.dst_port),
           dyn_count ); )
        return r;
}

/**
 * lookup dynamic parent rule using pkt and rule as search keys.
 * If the lookup fails, then install one.
 */
static ipfw_dyn_rule *
lookup_dyn_parent(struct ipfw_flow_id *pkt, struct ip_fw *rule)
{
        ipfw_dyn_rule *q;
        int i;

        if (ipfw_dyn_v) {
                i = hash_packet( pkt );
                for (q = ipfw_dyn_v[i] ; q != NULL ; q=q->next)
                        if (q->dyn_type == O_LIMIT_PARENT &&
                            rule== q->rule &&
                            pkt->proto == q->id.proto &&
                            pkt->src_ip == q->id.src_ip &&
                            pkt->dst_ip == q->id.dst_ip &&
                            pkt->src_port == q->id.src_port &&
                            pkt->dst_port == q->id.dst_port) {
                                q->expire = time_second + dyn_short_lifetime;
                                DEB(kprintf("lookup_dyn_parent found 0x%p\n",q);)
                                return q;
                        }
        }
        return add_dyn_rule(pkt, O_LIMIT_PARENT, rule);
}

/**
 * Install dynamic state for rule type cmd->o.opcode
 *
 * Returns 1 (failure) if state is not installed because of errors or because
 * session limitations are enforced.
 */
static int
install_state(struct ip_fw *rule, ipfw_insn_limit *cmd,
        struct ip_fw_args *args)
{
        static int last_log;

        ipfw_dyn_rule *q;

        DEB(kprintf("-- install state type %d 0x%08x %u -> 0x%08x %u\n",
            cmd->o.opcode,
            (args->f_id.src_ip), (args->f_id.src_port),
            (args->f_id.dst_ip), (args->f_id.dst_port) );)

        q = lookup_dyn_rule(&args->f_id, NULL, NULL);

        if (q != NULL) { /* should never occur */
                if (last_log != time_second) {
                        last_log = time_second;
                        kprintf(" install_state: entry already present, done\n");
                }
                return 0;
        }

        if (dyn_count >= dyn_max)
                /*
                 * Run out of slots, try to remove any expired rule.
                 */
                remove_dyn_rule(NULL, (ipfw_dyn_rule *)1);

        if (dyn_count >= dyn_max) {
                if (last_log != time_second) {
                        last_log = time_second;
                        kprintf("install_state: Too many dynamic rules\n");
                }
                return 1; /* cannot install, notify caller */
        }

        switch (cmd->o.opcode) {
        case O_KEEP_STATE: /* bidir rule */
                add_dyn_rule(&args->f_id, O_KEEP_STATE, rule);
                break;

        case O_LIMIT: /* limit number of sessions */
            {
                uint16_t limit_mask = cmd->limit_mask;
                struct ipfw_flow_id id;
                ipfw_dyn_rule *parent;

                DEB(kprintf("installing dyn-limit rule %d\n", cmd->conn_limit);)

                id.dst_ip = id.src_ip = 0;
                id.dst_port = id.src_port = 0;
                id.proto = args->f_id.proto;

                if (limit_mask & DYN_SRC_ADDR)
                        id.src_ip = args->f_id.src_ip;
                if (limit_mask & DYN_DST_ADDR)
                        id.dst_ip = args->f_id.dst_ip;
                if (limit_mask & DYN_SRC_PORT)
                        id.src_port = args->f_id.src_port;
                if (limit_mask & DYN_DST_PORT)
                        id.dst_port = args->f_id.dst_port;
                parent = lookup_dyn_parent(&id, rule);
                if (parent == NULL) {
                        kprintf("add parent failed\n");
                        return 1;
                }
                if (parent->count >= cmd->conn_limit) {
                        /*
                         * See if we can remove some expired rule.
                         */
                        remove_dyn_rule(rule, parent);
                        if (parent->count >= cmd->conn_limit) {
                                if (fw_verbose && last_log != time_second) {
                                        last_log = time_second;
                                        log(LOG_SECURITY | LOG_DEBUG,
                                            "drop session, too many entries\n");
                                }
                                return 1;
                        }
                }
                add_dyn_rule(&args->f_id, O_LIMIT, (struct ip_fw *)parent);
            }
                break;
        default:
                kprintf("unknown dynamic rule type %u\n", cmd->o.opcode);
                return 1;
        }
        lookup_dyn_rule(&args->f_id, NULL, NULL); /* XXX just set lifetime */
        return 0;
}

/*
 * Transmit a TCP packet, containing either a RST or a keepalive.
 * When flags & TH_RST, we are sending a RST packet, because of a
 * "reset" action matched the packet.
 * Otherwise we are sending a keepalive, and flags & TH_
 */
static void
send_pkt(struct ipfw_flow_id *id, uint32_t seq, uint32_t ack, int flags)
{
        struct mbuf *m;
        struct ip *ip;
        struct tcphdr *tcp;
        struct route sro;       /* fake route */

        MGETHDR(m, MB_DONTWAIT, MT_HEADER);
        if (m == 0)
                return;
        m->m_pkthdr.rcvif = (struct ifnet *)0;
        m->m_pkthdr.len = m->m_len = sizeof(struct ip) + sizeof(struct tcphdr);
        m->m_data += max_linkhdr;

        ip = mtod(m, struct ip *);
        bzero(ip, m->m_len);
        tcp = (struct tcphdr *)(ip + 1); /* no IP options */
        ip->ip_p = IPPROTO_TCP;
        tcp->th_off = 5;
        /*
         * Assume we are sending a RST (or a keepalive in the reverse
         * direction), swap src and destination addresses and ports.
         */
        ip->ip_src.s_addr = htonl(id->dst_ip);
        ip->ip_dst.s_addr = htonl(id->src_ip);
        tcp->th_sport = htons(id->dst_port);
        tcp->th_dport = htons(id->src_port);
        if (flags & TH_RST) {   /* we are sending a RST */
                if (flags & TH_ACK) {
                        tcp->th_seq = htonl(ack);
                        tcp->th_ack = htonl(0);
                        tcp->th_flags = TH_RST;
                } else {
                        if (flags & TH_SYN)
                                seq++;
                        tcp->th_seq = htonl(0);
                        tcp->th_ack = htonl(seq);
                        tcp->th_flags = TH_RST | TH_ACK;
                }
        } else {
                /*
                 * We are sending a keepalive. flags & TH_SYN determines
                 * the direction, forward if set, reverse if clear.
                 * NOTE: seq and ack are always assumed to be correct
                 * as set by the caller. This may be confusing...
                 */
                if (flags & TH_SYN) {
                        /*
                         * we have to rewrite the correct addresses!
                         */
                        ip->ip_dst.s_addr = htonl(id->dst_ip);
                        ip->ip_src.s_addr = htonl(id->src_ip);
                        tcp->th_dport = htons(id->dst_port);
                        tcp->th_sport = htons(id->src_port);
                }
                tcp->th_seq = htonl(seq);
                tcp->th_ack = htonl(ack);
                tcp->th_flags = TH_ACK;
        }
        /*
         * set ip_len to the payload size so we can compute
         * the tcp checksum on the pseudoheader
         * XXX check this, could save a couple of words ?
         */
        ip->ip_len = htons(sizeof(struct tcphdr));
        tcp->th_sum = in_cksum(m, m->m_pkthdr.len);
        /*
         * now fill fields left out earlier
         */
        ip->ip_ttl = ip_defttl;
        ip->ip_len = m->m_pkthdr.len;
        bzero (&sro, sizeof (sro));
        ip_rtaddr(ip->ip_dst, &sro);
        m->m_pkthdr.fw_flags |= IPFW_MBUF_GENERATED;
        ip_output(m, NULL, &sro, 0, NULL, NULL);
        if (sro.ro_rt)
                RTFREE(sro.ro_rt);
}

/*
 * sends a reject message, consuming the mbuf passed as an argument.
 */
static void
send_reject(struct ip_fw_args *args, int code, int offset, int ip_len)
{

        if (code != ICMP_REJECT_RST) { /* Send an ICMP unreach */
                /* We need the IP header in host order for icmp_error(). */
                if (args->eh != NULL) {
                        struct ip *ip = mtod(args->m, struct ip *);
                        ip->ip_len = ntohs(ip->ip_len);
                        ip->ip_off = ntohs(ip->ip_off);
                }
                icmp_error(args->m, ICMP_UNREACH, code, 0L, 0);
        } else if (offset == 0 && args->f_id.proto == IPPROTO_TCP) {
                struct tcphdr *const tcp =
                    L3HDR(struct tcphdr, mtod(args->m, struct ip *));
                if ( (tcp->th_flags & TH_RST) == 0)
                        send_pkt(&(args->f_id), ntohl(tcp->th_seq),
                                ntohl(tcp->th_ack),
                                tcp->th_flags | TH_RST);
                m_freem(args->m);
        } else
                m_freem(args->m);
        args->m = NULL;
}

/**
 *
 * Given an ip_fw *, lookup_next_rule will return a pointer
 * to the next rule, which can be either the jump
 * target (for skipto instructions) or the next one in the list (in
 * all other cases including a missing jump target).
 * The result is also written in the "next_rule" field of the rule.
 * Backward jumps are not allowed, so start looking from the next
 * rule...
 *
 * This never returns NULL -- in case we do not have an exact match,
 * the next rule is returned. When the ruleset is changed,
 * pointers are flushed so we are always correct.
 */

static struct ip_fw *
lookup_next_rule(struct ip_fw *me)
{
        struct ip_fw *rule = NULL;
        ipfw_insn *cmd;

        /* look for action, in case it is a skipto */
        cmd = ACTION_PTR(me);
        if (cmd->opcode == O_LOG)
                cmd += F_LEN(cmd);
        if ( cmd->opcode == O_SKIPTO )
                for (rule = me->next; rule ; rule = rule->next)
                        if (rule->rulenum >= cmd->arg1)
                                break;
        if (rule == NULL)                       /* failure or not a skipto */
                rule = me->next;
        me->next_rule = rule;
        return rule;
}

/*
 * The main check routine for the firewall.
 *
 * All arguments are in args so we can modify them and return them
 * back to the caller.
 *
 * Parameters:
 *
 *      args->m (in/out) The packet; we set to NULL when/if we nuke it.
 *              Starts with the IP header.
 *      args->eh (in)   Mac header if present, or NULL for layer3 packet.
 *      args->oif       Outgoing interface, or NULL if packet is incoming.
 *              The incoming interface is in the mbuf. (in)
 *
 *      args->rule      Pointer to the last matching rule (in/out)
 *      args->next_hop  Socket we are forwarding to (out).
 *      args->f_id      Addresses grabbed from the packet (out)
 *
 * Return value:
 *
 *      IP_FW_PORT_DENY_FLAG    the packet must be dropped.
 *      0       The packet is to be accepted and routed normally OR
 *              the packet was denied/rejected and has been dropped;
 *              in the latter case, *m is equal to NULL upon return.
 *      port    Divert the packet to port, with these caveats:
 *
 *              - If IP_FW_PORT_TEE_FLAG is set, tee the packet instead
 *                of diverting it (ie, 'ipfw tee').
 *
 *              - If IP_FW_PORT_DYNT_FLAG is set, interpret the lower
 *                16 bits as a dummynet pipe number instead of diverting
 */

static int
ipfw_chk(struct ip_fw_args *args)
{
        /*
         * Local variables hold state during the processing of a packet.
         *
         * IMPORTANT NOTE: to speed up the processing of rules, there
         * are some assumption on the values of the variables, which
         * are documented here. Should you change them, please check
         * the implementation of the various instructions to make sure
         * that they still work.
         *
         * args->eh     The MAC header. It is non-null for a layer2
         *      packet, it is NULL for a layer-3 packet.
         *
         * m | args->m  Pointer to the mbuf, as received from the caller.
         *      It may change if ipfw_chk() does an m_pullup, or if it
         *      consumes the packet because it calls send_reject().
         *      XXX This has to change, so that ipfw_chk() never modifies
         *      or consumes the buffer.
         * ip   is simply an alias of the value of m, and it is kept
         *      in sync with it (the packet is  supposed to start with
         *      the ip header).
         */
        struct mbuf *m = args->m;
        struct ip *ip = mtod(m, struct ip *);

        /*
         * oif | args->oif      If NULL, ipfw_chk has been called on the
         *      inbound path (ether_input, ip_input).
         *      If non-NULL, ipfw_chk has been called on the outbound path
         *      (ether_output, ip_output).
         */
        struct ifnet *oif = args->oif;

        struct ip_fw *f = NULL;         /* matching rule */
        int retval = 0;
        struct m_tag *mtag;

        /*
         * hlen The length of the IPv4 header.
         *      hlen >0 means we have an IPv4 packet.
         */
        u_int hlen = 0;         /* hlen >0 means we have an IP pkt */

        /*
         * offset       The offset of a fragment. offset != 0 means that
         *      we have a fragment at this offset of an IPv4 packet.
         *      offset == 0 means that (if this is an IPv4 packet)
         *      this is the first or only fragment.
         */
        u_short offset = 0;

        /*
         * Local copies of addresses. They are only valid if we have
         * an IP packet.
         *
         * proto        The protocol. Set to 0 for non-ip packets,
         *      or to the protocol read from the packet otherwise.
         *      proto != 0 means that we have an IPv4 packet.
         *
         * src_port, dst_port   port numbers, in HOST format. Only
         *      valid for TCP and UDP packets.
         *
         * src_ip, dst_ip       ip addresses, in NETWORK format.
         *      Only valid for IPv4 packets.
         */
        uint8_t proto;
        uint16_t src_port = 0, dst_port = 0;    /* NOTE: host format    */
        struct in_addr src_ip, dst_ip;          /* NOTE: network format */
        uint16_t ip_len=0;
        int dyn_dir = MATCH_UNKNOWN;
        ipfw_dyn_rule *q = NULL;

        if (m->m_pkthdr.fw_flags & IPFW_MBUF_GENERATED)
                return 0;       /* accept */
        /*
         * dyn_dir = MATCH_UNKNOWN when rules unchecked,
         *      MATCH_NONE when checked and not matched (q = NULL),
         *      MATCH_FORWARD or MATCH_REVERSE otherwise (q != NULL)
         */

        if (args->eh == NULL ||         /* layer 3 packet */
                ( m->m_pkthdr.len >= sizeof(struct ip) &&
                    ntohs(args->eh->ether_type) == ETHERTYPE_IP))
                        hlen = ip->ip_hl << 2;

        /*
         * Collect parameters into local variables for faster matching.
         */
        if (hlen == 0) {        /* do not grab addresses for non-ip pkts */
                proto = args->f_id.proto = 0;   /* mark f_id invalid */
                goto after_ip_checks;
        }

        proto = args->f_id.proto = ip->ip_p;
        src_ip = ip->ip_src;
        dst_ip = ip->ip_dst;
        if (args->eh != NULL) { /* layer 2 packets are as on the wire */
                offset = ntohs(ip->ip_off) & IP_OFFMASK;
                ip_len = ntohs(ip->ip_len);
        } else {
                offset = ip->ip_off & IP_OFFMASK;
                ip_len = ip->ip_len;
        }

#define PULLUP_TO(len)                                          \
                do {                                            \
                        if ((m)->m_len < (len)) {               \
                            args->m = m = m_pullup(m, (len));   \
                            if (m == 0)                         \
                                goto pullup_failed;             \
                            ip = mtod(m, struct ip *);          \
                        }                                       \
                } while (0)

        if (offset == 0) {
                switch (proto) {
                case IPPROTO_TCP:
                    {
                        struct tcphdr *tcp;

                        PULLUP_TO(hlen + sizeof(struct tcphdr));
                        tcp = L3HDR(struct tcphdr, ip);
                        dst_port = tcp->th_dport;
                        src_port = tcp->th_sport;
                        args->f_id.flags = tcp->th_flags;
                        }
                        break;

                case IPPROTO_UDP:
                    {
                        struct udphdr *udp;

                        PULLUP_TO(hlen + sizeof(struct udphdr));
                        udp = L3HDR(struct udphdr, ip);
                        dst_port = udp->uh_dport;
                        src_port = udp->uh_sport;
                        }
                        break;

                case IPPROTO_ICMP:
                        PULLUP_TO(hlen + 4);    /* type, code and checksum. */
                        args->f_id.flags = L3HDR(struct icmp, ip)->icmp_type;
                        break;

                default:
                        break;
                }
#undef PULLUP_TO
        }

        args->f_id.src_ip = ntohl(src_ip.s_addr);
        args->f_id.dst_ip = ntohl(dst_ip.s_addr);
        args->f_id.src_port = src_port = ntohs(src_port);
        args->f_id.dst_port = dst_port = ntohs(dst_port);

after_ip_checks:
        if (args->rule) {
                /*
                 * Packet has already been tagged. Look for the next rule
                 * to restart processing.
                 *
                 * If fw_one_pass != 0 then just accept it.
                 * XXX should not happen here, but optimized out in
                 * the caller.
                 */
                if (fw_one_pass)
                        return 0;

                /* This rule was deleted */
                if (args->rule->rule_flags & IPFW_RULE_F_INVALID)
                        return IP_FW_PORT_DENY_FLAG;

                f = args->rule->next_rule;
                if (f == NULL)
                        f = lookup_next_rule(args->rule);
        } else {
                /*
                 * Find the starting rule. It can be either the first
                 * one, or the one after divert_rule if asked so.
                 */
                int skipto;

                mtag = m_tag_find(m, PACKET_TAG_IPFW_DIVERT, NULL);
                if (mtag != NULL)
                        skipto = *(uint16_t *)m_tag_data(mtag);
                else
                        skipto = 0;

                f = layer3_chain;
                if (args->eh == NULL && skipto != 0) {
                        if (skipto >= IPFW_DEFAULT_RULE)
                                return(IP_FW_PORT_DENY_FLAG); /* invalid */
                        while (f && f->rulenum <= skipto)
                                f = f->next;
                        if (f == NULL)  /* drop packet */
                                return(IP_FW_PORT_DENY_FLAG);
                }
        }
        if ((mtag = m_tag_find(m, PACKET_TAG_IPFW_DIVERT, NULL)) != NULL)
                m_tag_delete(m, mtag);

        /*
         * Now scan the rules, and parse microinstructions for each rule.
         */
        for (; f; f = f->next) {
                int l, cmdlen;
                ipfw_insn *cmd;
                int skip_or; /* skip rest of OR block */

again:
                if (set_disable & (1 << f->set) )
                        continue;

                skip_or = 0;
                for (l = f->cmd_len, cmd = f->cmd ; l > 0 ;
                    l -= cmdlen, cmd += cmdlen) {
                        int match;

                        /*
                         * check_body is a jump target used when we find a
                         * CHECK_STATE, and need to jump to the body of
                         * the target rule.
                         */

check_body:
                        cmdlen = F_LEN(cmd);
                        /*
                         * An OR block (insn_1 || .. || insn_n) has the
                         * F_OR bit set in all but the last instruction.
                         * The first match will set "skip_or", and cause
                         * the following instructions to be skipped until
                         * past the one with the F_OR bit clear.
                         */
                        if (skip_or) {          /* skip this instruction */
                                if ((cmd->len & F_OR) == 0)
                                        skip_or = 0;    /* next one is good */
                                continue;
                        }
                        match = 0; /* set to 1 if we succeed */

                        switch (cmd->opcode) {
                        /*
                         * The first set of opcodes compares the packet's
                         * fields with some pattern, setting 'match' if a
                         * match is found. At the end of the loop there is
                         * logic to deal with F_NOT and F_OR flags associated
                         * with the opcode.
                         */
                        case O_NOP:
                                match = 1;
                                break;

                        case O_FORWARD_MAC:
                                kprintf("ipfw: opcode %d unimplemented\n",
                                    cmd->opcode);
                                break;

                        case O_GID:
                        case O_UID:
                                /*
                                 * We only check offset == 0 && proto != 0,
                                 * as this ensures that we have an IPv4
                                 * packet with the ports info.
                                 */
                                if (offset!=0)
                                        break;
                            {
                                struct inpcbinfo *pi;
                                int wildcard;
                                struct inpcb *pcb;

                                if (proto == IPPROTO_TCP) {
                                        wildcard = 0;
                                        pi = &tcbinfo[mycpu->gd_cpuid];
                                } else if (proto == IPPROTO_UDP) {
                                        wildcard = 1;
                                        pi = &udbinfo;
                                } else
                                        break;

                                pcb =  (oif) ?
                                        in_pcblookup_hash(pi,
                                            dst_ip, htons(dst_port),
                                            src_ip, htons(src_port),
                                            wildcard, oif) :
                                        in_pcblookup_hash(pi,
                                            src_ip, htons(src_port),
                                            dst_ip, htons(dst_port),
                                            wildcard, NULL);

                                if (pcb == NULL || pcb->inp_socket == NULL)
                                        break;
#if defined(__DragonFly__) || (defined(__FreeBSD__) && __FreeBSD_version < 500034)
#define socheckuid(a,b) ((a)->so_cred->cr_uid != (b))
#endif
                                if (cmd->opcode == O_UID) {
                                        match =
                                          !socheckuid(pcb->inp_socket,
                                           (uid_t)((ipfw_insn_u32 *)cmd)->d[0]);
                                } else  {
                                        match = groupmember(
                                            (uid_t)((ipfw_insn_u32 *)cmd)->d[0],
                                            pcb->inp_socket->so_cred);
                                }
                            }
                                break;

                        case O_RECV:
                                match = iface_match(m->m_pkthdr.rcvif,
                                    (ipfw_insn_if *)cmd);
                                break;

                        case O_XMIT:
                                match = iface_match(oif, (ipfw_insn_if *)cmd);
                                break;

                        case O_VIA:
                                match = iface_match(oif ? oif :
                                    m->m_pkthdr.rcvif, (ipfw_insn_if *)cmd);
                                break;

                        case O_MACADDR2:
                                if (args->eh != NULL) { /* have MAC header */
                                        uint32_t *want = (uint32_t *)
                                                ((ipfw_insn_mac *)cmd)->addr;
                                        uint32_t *mask = (uint32_t *)
                                                ((ipfw_insn_mac *)cmd)->mask;
                                        uint32_t *hdr = (uint32_t *)args->eh;

                                        match =
                                            ( want[0] == (hdr[0] & mask[0]) &&
                                              want[1] == (hdr[1] & mask[1]) &&
                                              want[2] == (hdr[2] & mask[2]) );
                                }
                                break;

                        case O_MAC_TYPE:
                                if (args->eh != NULL) {
                                        uint16_t t =
                                            ntohs(args->eh->ether_type);
                                        uint16_t *p =
                                            ((ipfw_insn_u16 *)cmd)->ports;
                                        int i;

                                        for (i = cmdlen - 1; !match && i>0;
                                            i--, p += 2)
                                                match = (t>=p[0] && t<=p[1]);
                                }
                                break;

                        case O_FRAG:
                                match = (hlen > 0 && offset != 0);
                                break;

                        case O_IN:      /* "out" is "not in" */
                                match = (oif == NULL);
                                break;

                        case O_LAYER2:
                                match = (args->eh != NULL);
                                break;

                        case O_PROTO:
                                /*
                                 * We do not allow an arg of 0 so the
                                 * check of "proto" only suffices.
                                 */
                                match = (proto == cmd->arg1);
                                break;

                        case O_IP_SRC:
                                match = (hlen > 0 &&
                                    ((ipfw_insn_ip *)cmd)->addr.s_addr ==
                                    src_ip.s_addr);
                                break;

                        case O_IP_SRC_MASK:
                                match = (hlen > 0 &&
                                    ((ipfw_insn_ip *)cmd)->addr.s_addr ==
                                     (src_ip.s_addr &
                                     ((ipfw_insn_ip *)cmd)->mask.s_addr));
                                break;

                        case O_IP_SRC_ME:
                                if (hlen > 0) {
                                        struct ifnet *tif;

                                        INADDR_TO_IFP(src_ip, tif);
                                        match = (tif != NULL);
                                }
                                break;

                        case O_IP_DST_SET:
                        case O_IP_SRC_SET:
                                if (hlen > 0) {
                                        uint32_t *d = (uint32_t *)(cmd+1);
                                        uint32_t addr =
                                            cmd->opcode == O_IP_DST_SET ?
                                                args->f_id.dst_ip :
                                                args->f_id.src_ip;

                                            if (addr < d[0])
                                                    break;
                                            addr -= d[0]; /* subtract base */
                                            match = (addr < cmd->arg1) &&
                                                ( d[ 1 + (addr>>5)] &
                                                  (1<<(addr & 0x1f)) );
                                }
                                break;

                        case O_IP_DST:
                                match = (hlen > 0 &&
                                    ((ipfw_insn_ip *)cmd)->addr.s_addr ==
                                    dst_ip.s_addr);
                                break;

                        case O_IP_DST_MASK:
                                match = (hlen > 0) &&
                                    (((ipfw_insn_ip *)cmd)->addr.s_addr ==
                                     (dst_ip.s_addr &
                                     ((ipfw_insn_ip *)cmd)->mask.s_addr));
                                break;

                        case O_IP_DST_ME:
                                if (hlen > 0) {
                                        struct ifnet *tif;

                                        INADDR_TO_IFP(dst_ip, tif);
                                        match = (tif != NULL);
                                }
                                break;

                        case O_IP_SRCPORT:
                        case O_IP_DSTPORT:
                                /*
                                 * offset == 0 && proto != 0 is enough
                                 * to guarantee that we have an IPv4
                                 * packet with port info.
                                 */
                                if ((proto==IPPROTO_UDP || proto==IPPROTO_TCP)
                                    && offset == 0) {
                                        uint16_t x =
                                            (cmd->opcode == O_IP_SRCPORT) ?
                                                src_port : dst_port ;
                                        uint16_t *p =
                                            ((ipfw_insn_u16 *)cmd)->ports;
                                        int i;

                                        for (i = cmdlen - 1; !match && i>0;
                                            i--, p += 2)
                                                match = (x>=p[0] && x<=p[1]);
                                }
                                break;

                        case O_ICMPTYPE:
                                match = (offset == 0 && proto==IPPROTO_ICMP &&
                                    icmptype_match(ip, (ipfw_insn_u32 *)cmd) );
                                break;

                        case O_IPOPT:
                                match = (hlen > 0 && ipopts_match(ip, cmd) );
                                break;

                        case O_IPVER:
                                match = (hlen > 0 && cmd->arg1 == ip->ip_v);
                                break;

                        case O_IPTTL:
                                match = (hlen > 0 && cmd->arg1 == ip->ip_ttl);
                                break;

                        case O_IPID:
                                match = (hlen > 0 &&
                                    cmd->arg1 == ntohs(ip->ip_id));
                                break;

                        case O_IPLEN:
                                match = (hlen > 0 && cmd->arg1 == ip_len);
                                break;

                        case O_IPPRECEDENCE:
                                match = (hlen > 0 &&
                                    (cmd->arg1 == (ip->ip_tos & 0xe0)) );
                                break;

                        case O_IPTOS:
                                match = (hlen > 0 &&
                                    flags_match(cmd, ip->ip_tos));
                                break;

                        case O_TCPFLAGS:
                                match = (proto == IPPROTO_TCP && offset == 0 &&
                                    flags_match(cmd,
                                        L3HDR(struct tcphdr,ip)->th_flags));
                                break;

                        case O_TCPOPTS:
                                match = (proto == IPPROTO_TCP && offset == 0 &&
                                    tcpopts_match(ip, cmd));
                                break;

                        case O_TCPSEQ:
                                match = (proto == IPPROTO_TCP && offset == 0 &&
                                    ((ipfw_insn_u32 *)cmd)->d[0] ==
                                        L3HDR(struct tcphdr,ip)->th_seq);
                                break;

                        case O_TCPACK:
                                match = (proto == IPPROTO_TCP && offset == 0 &&
                                    ((ipfw_insn_u32 *)cmd)->d[0] ==
                                        L3HDR(struct tcphdr,ip)->th_ack);
                                break;

                        case O_TCPWIN:
                                match = (proto == IPPROTO_TCP && offset == 0 &&
                                    cmd->arg1 ==
                                        L3HDR(struct tcphdr,ip)->th_win);
                                break;

                        case O_ESTAB:
                                /* reject packets which have SYN only */
                                /* XXX should i also check for TH_ACK ? */
                                match = (proto == IPPROTO_TCP && offset == 0 &&
                                    (L3HDR(struct tcphdr,ip)->th_flags &
                                     (TH_RST | TH_ACK | TH_SYN)) != TH_SYN);
                                break;

                        case O_LOG:
                                if (fw_verbose)
                                        ipfw_log(f, hlen, args->eh, m, oif);
                                match = 1;
                                break;

                        case O_PROB:
                                match = (krandom() <
                                        ((ipfw_insn_u32 *)cmd)->d[0]);
                                break;

                        /*
                         * The second set of opcodes represents 'actions',
                         * i.e. the terminal part of a rule once the packet
                         * matches all previous patterns.
                         * Typically there is only one action for each rule,
                         * and the opcode is stored at the end of the rule
                         * (but there are exceptions -- see below).
                         *
                         * In general, here we set retval and terminate the
                         * outer loop (would be a 'break 3' in some language,
                         * but we need to do a 'goto done').
                         *
                         * Exceptions:
                         * O_COUNT and O_SKIPTO actions:
                         *   instead of terminating, we jump to the next rule
                         *   ('goto next_rule', equivalent to a 'break 2'),
                         *   or to the SKIPTO target ('goto again' after
                         *   having set f, cmd and l), respectively.
                         *
                         * O_LIMIT and O_KEEP_STATE: these opcodes are
                         *   not real 'actions', and are stored right
                         *   before the 'action' part of the rule.
                         *   These opcodes try to install an entry in the
                         *   state tables; if successful, we continue with
                         *   the next opcode (match=1; break;), otherwise
                         *   the packet *   must be dropped
                         *   ('goto done' after setting retval);
                         *
                         * O_PROBE_STATE and O_CHECK_STATE: these opcodes
                         *   cause a lookup of the state table, and a jump
                         *   to the 'action' part of the parent rule
                         *   ('goto check_body') if an entry is found, or
                         *   (CHECK_STATE only) a jump to the next rule if
                         *   the entry is not found ('goto next_rule').
                         *   The result of the lookup is cached to make
                         *   further instances of these opcodes are
                         *   effectively NOPs.
                         */
                        case O_LIMIT:
                        case O_KEEP_STATE:
                                if (install_state(f,
                                    (ipfw_insn_limit *)cmd, args)) {
                                        retval = IP_FW_PORT_DENY_FLAG;
                                        goto done; /* error/limit violation */
                                }
                                match = 1;
                                break;

                        case O_PROBE_STATE:
                        case O_CHECK_STATE:
                                /*
                                 * dynamic rules are checked at the first
                                 * keep-state or check-state occurrence,
                                 * with the result being stored in dyn_dir.
                                 * The compiler introduces a PROBE_STATE
                                 * instruction for us when we have a
                                 * KEEP_STATE (because PROBE_STATE needs
                                 * to be run first).
                                 */
                                if (dyn_dir == MATCH_UNKNOWN &&
                                    (q = lookup_dyn_rule(&args->f_id,
                                     &dyn_dir, proto == IPPROTO_TCP ?
                                        L3HDR(struct tcphdr, ip) : NULL))
                                        != NULL) {
                                        /*
                                         * Found dynamic entry, update stats
                                         * and jump to the 'action' part of
                                         * the parent rule.
                                         */
                                        q->pcnt++;
                                        q->bcnt += ip_len;
                                        f = q->rule;
                                        cmd = ACTION_PTR(f);
                                        l = f->cmd_len - f->act_ofs;
                                        goto check_body;
                                }
                                /*
                                 * Dynamic entry not found. If CHECK_STATE,
                                 * skip to next rule, if PROBE_STATE just
                                 * ignore and continue with next opcode.
                                 */
                                if (cmd->opcode == O_CHECK_STATE)
                                        goto next_rule;
                                match = 1;
                                break;

                        case O_ACCEPT:
                                retval = 0;     /* accept */
                                goto done;

                        case O_PIPE:
                        case O_QUEUE:
                                args->rule = f; /* report matching rule */
                                retval = cmd->arg1 | IP_FW_PORT_DYNT_FLAG;
                                goto done;

                        case O_DIVERT:
                        case O_TEE:
                                if (args->eh) /* not on layer 2 */
                                        break;

                                mtag = m_tag_get(PACKET_TAG_IPFW_DIVERT,
                                                 sizeof(uint16_t), MB_DONTWAIT);
                                if (mtag == NULL) {
                                        retval = IP_FW_PORT_DENY_FLAG;
                                        goto done;
                                }
                                *(uint16_t *)m_tag_data(mtag) = f->rulenum;
                                m_tag_prepend(m, mtag);
                                retval = (cmd->opcode == O_DIVERT) ?
                                    cmd->arg1 :
                                    cmd->arg1 | IP_FW_PORT_TEE_FLAG;
                                goto done;

                        case O_COUNT:
                        case O_SKIPTO:
                                f->pcnt++;      /* update stats */
                                f->bcnt += ip_len;
                                f->timestamp = time_second;
                                if (cmd->opcode == O_COUNT)
                                        goto next_rule;
                                /* handle skipto */
                                if (f->next_rule == NULL)
                                        lookup_next_rule(f);
                                f = f->next_rule;
                                goto again;

                        case O_REJECT:
                                /*
                                 * Drop the packet and send a reject notice
                                 * if the packet is not ICMP (or is an ICMP
                                 * query), and it is not multicast/broadcast.
                                 */
                                if (hlen > 0 &&
                                    (proto != IPPROTO_ICMP ||
                                     is_icmp_query(ip)) &&
                                    !(m->m_flags & (M_BCAST|M_MCAST)) &&
                                    !IN_MULTICAST(ntohl(dst_ip.s_addr))) {
                                        send_reject(args, cmd->arg1,
                                            offset,ip_len);
                                        m = args->m;
                                }
                                /* FALLTHROUGH */
                        case O_DENY:
                                retval = IP_FW_PORT_DENY_FLAG;
                                goto done;

                        case O_FORWARD_IP:
                                if (args->eh)   /* not valid on layer2 pkts */
                                        break;
                                if (!q || dyn_dir == MATCH_FORWARD)
                                        args->next_hop =
                                            &((ipfw_insn_sa *)cmd)->sa;
                                retval = 0;
                                goto done;

                        default:
                                panic("-- unknown opcode %d\n", cmd->opcode);
                        } /* end of switch() on opcodes */

                        if (cmd->len & F_NOT)
                                match = !match;

                        if (match) {
                                if (cmd->len & F_OR)
                                        skip_or = 1;
                        } else {
                                if (!(cmd->len & F_OR)) /* not an OR block, */
                                        break;          /* try next rule    */
                        }

                }       /* end of inner for, scan opcodes */

next_rule:;             /* try next rule                */

        }               /* end of outer for, scan rules */
        kprintf("+++ ipfw: ouch!, skip past end of rules, denying packet\n");
        return(IP_FW_PORT_DENY_FLAG);

done:
        /* Update statistics */
        f->pcnt++;
        f->bcnt += ip_len;
        f->timestamp = time_second;
        return retval;

pullup_failed:
        if (fw_verbose)
                kprintf("pullup failed\n");
        return(IP_FW_PORT_DENY_FLAG);
}

static void
ipfw_dummynet_io(struct mbuf *m, int pipe_nr, int dir, struct ip_fw_args *fwa)
{
        struct m_tag *mtag;
        struct dn_pkt *pkt;
        ipfw_insn *cmd;
        const struct ipfw_flow_id *id;
        struct dn_flow_id *fid;

        M_ASSERTPKTHDR(m);

        mtag = m_tag_get(PACKET_TAG_DUMMYNET, sizeof(*pkt), MB_DONTWAIT);
        if (mtag == NULL) {
                m_freem(m);
                return;
        }
        m_tag_prepend(m, mtag);

        pkt = m_tag_data(mtag);
        bzero(pkt, sizeof(*pkt));

        cmd = fwa->rule->cmd + fwa->rule->act_ofs;
        if (cmd->opcode == O_LOG)
                cmd += F_LEN(cmd);
        KASSERT(cmd->opcode == O_PIPE || cmd->opcode == O_QUEUE,
                ("Rule is not PIPE or QUEUE, opcode %d\n", cmd->opcode));

        pkt->dn_m = m;
        pkt->dn_flags = (dir & DN_FLAGS_DIR_MASK);
        pkt->ifp = fwa->oif;
        pkt->cpuid = mycpu->gd_cpuid;
        pkt->pipe_nr = pipe_nr;

        id = &fwa->f_id;
        fid = &pkt->id;
        fid->fid_dst_ip = id->dst_ip;
        fid->fid_src_ip = id->src_ip;
        fid->fid_dst_port = id->dst_port;
        fid->fid_src_port = id->src_port;
        fid->fid_proto = id->proto;
        fid->fid_flags = id->flags;

        ipfw_ref_rule(fwa->rule);
        pkt->dn_priv = fwa->rule;
        pkt->dn_unref_priv = ipfw_unref_rule;

        if (cmd->opcode == O_PIPE)
                pkt->dn_flags |= DN_FLAGS_IS_PIPE;

        if (dir == DN_TO_IP_OUT) {
                /*
                 * We need to copy *ro because for ICMP pkts (and maybe
                 * others) the caller passed a pointer into the stack;
                 * dst might also be a pointer into *ro so it needs to
                 * be updated.
                 */
                pkt->ro = *(fwa->ro);
                if (fwa->ro->ro_rt)
                        fwa->ro->ro_rt->rt_refcnt++;
                if (fwa->dst == (struct sockaddr_in *)&fwa->ro->ro_dst) {
                        /* 'dst' points into 'ro' */
                        fwa->dst = (struct sockaddr_in *)&(pkt->ro.ro_dst);
                }
                pkt->dn_dst = fwa->dst;
                pkt->flags = fwa->flags;
        }

        m->m_pkthdr.fw_flags |= DUMMYNET_MBUF_TAGGED;
        ip_dn_queue(m);
}

/*
 * When a rule is added/deleted, clear the next_rule pointers in all rules.
 * These will be reconstructed on the fly as packets are matched.
 * Must be called at splimp().
 */
static void
flush_rule_ptrs(void)
{
        struct ip_fw *rule;

        for (rule = layer3_chain; rule; rule = rule->next)
                rule->next_rule = NULL;
}

static __inline void
ipfw_inc_static_count(struct ip_fw *rule)
{
        static_count++;
        static_ioc_len += IOC_RULESIZE(rule);
}

static __inline void
ipfw_dec_static_count(struct ip_fw *rule)
{
        int l = IOC_RULESIZE(rule);

        KASSERT(static_count > 0, ("invalid static count %u\n", static_count));
        static_count--;

        KASSERT(static_ioc_len >= l,
                ("invalid static len %u\n", static_ioc_len));
        static_ioc_len -= l;
}

static struct ip_fw *
ipfw_create_rule(const struct ipfw_ioc_rule *ioc_rule)
{
        struct ip_fw *rule;

        rule = kmalloc(RULESIZE(ioc_rule), M_IPFW, M_WAITOK | M_ZERO);

        rule->act_ofs = ioc_rule->act_ofs;
        rule->cmd_len = ioc_rule->cmd_len;
        rule->rulenum = ioc_rule->rulenum;
        rule->set = ioc_rule->set;
        rule->usr_flags = ioc_rule->usr_flags;

        bcopy(ioc_rule->cmd, rule->cmd, rule->cmd_len * 4 /* XXX */);

        rule->refcnt = 1;

        return rule;
}

/*
 * Add a new rule to the list. Copy the rule into a malloc'ed area, then
 * possibly create a rule number and add the rule to the list.
 * Update the rule_number in the input struct so the caller knows it as well.
 */
static int
ipfw_add_rule(struct ip_fw **head, struct ipfw_ioc_rule *ioc_rule)
{
        struct ip_fw *rule, *f, *prev;

        KKASSERT(*head != NULL);

        rule = ipfw_create_rule(ioc_rule);

        crit_enter();

        /*
         * If rulenum is 0, find highest numbered rule before the
         * default rule, and add autoinc_step
         */
        if (autoinc_step < 1)
                autoinc_step = 1;
        else if (autoinc_step > 1000)
                autoinc_step = 1000;
        if (rule->rulenum == 0) {
                /*
                 * locate the highest numbered rule before default
                 */
                for (f = *head; f; f = f->next) {
                        if (f->rulenum == IPFW_DEFAULT_RULE)
                                break;
                        rule->rulenum = f->rulenum;
                }
                if (rule->rulenum < IPFW_DEFAULT_RULE - autoinc_step)
                        rule->rulenum += autoinc_step;
                ioc_rule->rulenum = rule->rulenum;
        }

        /*
         * Now insert the new rule in the right place in the sorted list.
         */
        for (prev = NULL, f = *head; f; prev = f, f = f->next) {
                if (f->rulenum > rule->rulenum) { /* found the location */
                        if (prev) {
                                rule->next = f;
                                prev->next = rule;
                        } else { /* head insert */
                                rule->next = *head;
                                *head = rule;
                        }
                        break;
                }
        }

        flush_rule_ptrs();
        ipfw_inc_static_count(rule);

        crit_exit();

        DEB(kprintf("++ installed rule %d, static count now %d\n",
                rule->rulenum, static_count);)
        return (0);
}

/**
 * Free storage associated with a static rule (including derived
 * dynamic rules).
 * The caller is in charge of clearing rule pointers to avoid
 * dangling pointers.
 * @return a pointer to the next entry.
 * Arguments are not checked, so they better be correct.
 * Must be called at splimp().
 */
static struct ip_fw *
delete_rule(struct ip_fw **head, struct ip_fw *prev, struct ip_fw *rule)
{
        struct ip_fw *n;

        n = rule->next;
        remove_dyn_rule(rule, NULL /* force removal */);
        if (prev == NULL)
                *head = n;
        else
                prev->next = n;
        ipfw_dec_static_count(rule);

        /* Mark the rule as invalid */
        rule->rule_flags |= IPFW_RULE_F_INVALID;
        rule->next_rule = NULL;

        /* Try to free this rule */
        ipfw_free_rule(rule);

        return n;
}

/*
 * Deletes all rules from a chain (including the default rule
 * if the second argument is set).
 * Must be called at splimp().
 */
static void
free_chain(struct ip_fw **chain, int kill_default)
{
        struct ip_fw *rule;

        flush_rule_ptrs(); /* more efficient to do outside the loop */

        while ( (rule = *chain) != NULL &&
            (kill_default || rule->rulenum != IPFW_DEFAULT_RULE) )
                delete_rule(chain, NULL, rule);

        KASSERT(dyn_count == 0, ("%u dyn rule remains\n", dyn_count));

        if (kill_default) {
                ip_fw_default_rule = NULL;      /* Reset default rule */

                if (ipfw_dyn_v != NULL) {
                        /*
                         * Free dynamic rules(state) hash table
                         */
                        kfree(ipfw_dyn_v, M_IPFW);
                        ipfw_dyn_v = NULL;
                }

                KASSERT(static_count == 0,
                        ("%u static rules remains\n", static_count));
                KASSERT(static_ioc_len == 0,
                        ("%u bytes of static rules remains\n", static_ioc_len));
        } else {
                KASSERT(static_count == 1,
                        ("%u static rules remains\n", static_count));
                KASSERT(static_ioc_len == IOC_RULESIZE(ip_fw_default_rule),
                        ("%u bytes of static rules remains, should be %u\n",
                         static_ioc_len, IOC_RULESIZE(ip_fw_default_rule)));
        }
}

/**
 * Remove all rules with given number, and also do set manipulation.
 *
 * The argument is an uint32_t. The low 16 bit are the rule or set number,
 * the next 8 bits are the new set, the top 8 bits are the command:
 *
 *      0       delete rules with given number
 *      1       delete rules with given set number
 *      2       move rules with given number to new set
 *      3       move rules with given set number to new set
 *      4       swap sets with given numbers
 */
static int
del_entry(struct ip_fw **chain, uint32_t arg)
{
        struct ip_fw *prev, *rule;
        uint16_t rulenum;
        uint8_t cmd, new_set;

        rulenum = arg & 0xffff;
        cmd = (arg >> 24) & 0xff;
        new_set = (arg >> 16) & 0xff;

        if (cmd > 4)
                return EINVAL;
        if (new_set > 30)
                return EINVAL;
        if (cmd == 0 || cmd == 2) {
                if (rulenum == IPFW_DEFAULT_RULE)
                        return EINVAL;
        } else {
                if (rulenum > 30)
                        return EINVAL;
        }

        switch (cmd) {
        case 0: /* delete rules with given number */
                /*
                 * locate first rule to delete
                 */
                for (prev = NULL, rule = *chain;
                    rule && rule->rulenum < rulenum;
                     prev = rule, rule = rule->next)
                        ;
                if (rule->rulenum != rulenum)
                        return EINVAL;

                crit_enter(); /* no access to rules while removing */
                /*
                 * flush pointers outside the loop, then delete all matching
                 * rules. prev remains the same throughout the cycle.
                 */
                flush_rule_ptrs();
                while (rule && rule->rulenum == rulenum)
                        rule = delete_rule(chain, prev, rule);
                crit_exit();
                break;

        case 1: /* delete all rules with given set number */
                crit_enter();
                flush_rule_ptrs();
                for (prev = NULL, rule = *chain; rule ; )
                        if (rule->set == rulenum)
                                rule = delete_rule(chain, prev, rule);
                        else {
                                prev = rule;
                                rule = rule->next;
                        }
                crit_exit();
                break;

        case 2: /* move rules with given number to new set */
                crit_enter();
                for (rule = *chain; rule ; rule = rule->next)
                        if (rule->rulenum == rulenum)
                                rule->set = new_set;
                crit_exit();
                break;

        case 3: /* move rules with given set number to new set */
                crit_enter();
                for (rule = *chain; rule ; rule = rule->next)
                        if (rule->set == rulenum)
                                rule->set = new_set;
                crit_exit();
                break;

        case 4: /* swap two sets */
                crit_enter();
                for (rule = *chain; rule ; rule = rule->next)
                        if (rule->set == rulenum)
                                rule->set = new_set;
                        else if (rule->set == new_set)
                                rule->set = rulenum;
                crit_exit();
                break;
        }
        return 0;
}

/*
 * Clear counters for a specific rule.
 */
static void
clear_counters(struct ip_fw *rule, int log_only)
{
        ipfw_insn_log *l = (ipfw_insn_log *)ACTION_PTR(rule);

        if (log_only == 0) {
                rule->bcnt = rule->pcnt = 0;
                rule->timestamp = 0;
        }
        if (l->o.opcode == O_LOG)
                l->log_left = l->max_log;
}

/**
 * Reset some or all counters on firewall rules.
 * @arg frwl is null to clear all entries, or contains a specific
 * rule number.
 * @arg log_only is 1 if we only want to reset logs, zero otherwise.
 */
static int
zero_entry(int rulenum, int log_only)
{
        struct ip_fw *rule;
        char *msg;

        if (rulenum == 0) {
                crit_enter();
                norule_counter = 0;
                for (rule = layer3_chain; rule; rule = rule->next)
                        clear_counters(rule, log_only);
                crit_exit();
                msg = log_only ? "ipfw: All logging counts reset.\n" :
                                "ipfw: Accounting cleared.\n";
        } else {
                int cleared = 0;
                /*
                 * We can have multiple rules with the same number, so we
                 * need to clear them all.
                 */
                for (rule = layer3_chain; rule; rule = rule->next)
                        if (rule->rulenum == rulenum) {
                                crit_enter();
                                while (rule && rule->rulenum == rulenum) {
                                        clear_counters(rule, log_only);
                                        rule = rule->next;
                                }
                                crit_exit();
                                cleared = 1;
                                break;
                        }
                if (!cleared)   /* we did not find any matching rules */
                        return (EINVAL);
                msg = log_only ? "ipfw: Entry %d logging count reset.\n" :
                                "ipfw: Entry %d cleared.\n";
        }
        if (fw_verbose)
                log(LOG_SECURITY | LOG_NOTICE, msg, rulenum);
        return (0);
}

/*
 * Check validity of the structure before insert.
 * Fortunately rules are simple, so this mostly need to check rule sizes.
 */
static int
ipfw_ctl_check_rule(struct ipfw_ioc_rule *rule, int size)
{
        int l, cmdlen = 0;
        int have_action = 0;
        ipfw_insn *cmd;

        /* Check for valid size */
        if (size < sizeof(*rule)) {
                kprintf("ipfw: rule too short\n");
                return EINVAL;
        }
        l = IOC_RULESIZE(rule);
        if (l != size) {
                kprintf("ipfw: size mismatch (have %d want %d)\n", size, l);
                return EINVAL;
        }

        /*
         * Now go for the individual checks. Very simple ones, basically only
         * instruction sizes.
         */
        for (l = rule->cmd_len, cmd = rule->cmd; l > 0;
             l -= cmdlen, cmd += cmdlen) {
                cmdlen = F_LEN(cmd);
                if (cmdlen > l) {
                        kprintf("ipfw: opcode %d size truncated\n",
                            cmd->opcode);
                        return EINVAL;
                }
                DEB(kprintf("ipfw: opcode %d\n", cmd->opcode);)
                switch (cmd->opcode) {
                case O_NOP:
                case O_PROBE_STATE:
                case O_KEEP_STATE:
                case O_PROTO:
                case O_IP_SRC_ME:
                case O_IP_DST_ME:
                case O_LAYER2:
                case O_IN:
                case O_FRAG:
                case O_IPOPT:
                case O_IPLEN:
                case O_IPID:
                case O_IPTOS:
                case O_IPPRECEDENCE:
                case O_IPTTL:
                case O_IPVER:
                case O_TCPWIN:
                case O_TCPFLAGS:
                case O_TCPOPTS:
                case O_ESTAB:
                        if (cmdlen != F_INSN_SIZE(ipfw_insn))
                                goto bad_size;
                        break;

                case O_UID:
                case O_GID:
                case O_IP_SRC:
                case O_IP_DST:
                case O_TCPSEQ:
                case O_TCPACK:
                case O_PROB:
                case O_ICMPTYPE:
                        if (cmdlen != F_INSN_SIZE(ipfw_insn_u32))
                                goto bad_size;
                        break;

                case O_LIMIT:
                        if (cmdlen != F_INSN_SIZE(ipfw_insn_limit))
                                goto bad_size;
                        break;

                case O_LOG:
                        if (cmdlen != F_INSN_SIZE(ipfw_insn_log))
                                goto bad_size;

                        ((ipfw_insn_log *)cmd)->log_left =
                            ((ipfw_insn_log *)cmd)->max_log;

                        break;

                case O_IP_SRC_MASK:
                case O_IP_DST_MASK:
                        if (cmdlen != F_INSN_SIZE(ipfw_insn_ip))
                                goto bad_size;
                        if (((ipfw_insn_ip *)cmd)->mask.s_addr == 0) {
                                kprintf("ipfw: opcode %d, useless rule\n",
                                        cmd->opcode);
                                return EINVAL;
                        }
                        break;

                case O_IP_SRC_SET:
                case O_IP_DST_SET:
                        if (cmd->arg1 == 0 || cmd->arg1 > 256) {
                                kprintf("ipfw: invalid set size %d\n",
                                        cmd->arg1);
                                return EINVAL;
                        }
                        if (cmdlen != F_INSN_SIZE(ipfw_insn_u32) +
                            (cmd->arg1+31)/32 )
                                goto bad_size;
                        break;

                case O_MACADDR2:
                        if (cmdlen != F_INSN_SIZE(ipfw_insn_mac))
                                goto bad_size;
                        break;

                case O_MAC_TYPE:
                case O_IP_SRCPORT:
                case O_IP_DSTPORT: /* XXX artificial limit, 30 port pairs */
                        if (cmdlen < 2 || cmdlen > 31)
                                goto bad_size;
                        break;

                case O_RECV:
                case O_XMIT:
                case O_VIA:
                        if (cmdlen != F_INSN_SIZE(ipfw_insn_if))
                                goto bad_size;
                        break;

                case O_PIPE:
                case O_QUEUE:
                        if (cmdlen != F_INSN_SIZE(ipfw_insn_pipe))
                                goto bad_size;
                        goto check_action;

                case O_FORWARD_IP:
                        if (cmdlen != F_INSN_SIZE(ipfw_insn_sa))
                                goto bad_size;
                        goto check_action;

                case O_FORWARD_MAC: /* XXX not implemented yet */
                case O_CHECK_STATE:
                case O_COUNT:
                case O_ACCEPT:
                case O_DENY:
                case O_REJECT:
                case O_SKIPTO:
                case O_DIVERT:
                case O_TEE:
                        if (cmdlen != F_INSN_SIZE(ipfw_insn))
                                goto bad_size;
check_action:
                        if (have_action) {
                                kprintf("ipfw: opcode %d, multiple actions"
                                        " not allowed\n",
                                        cmd->opcode);
                                return EINVAL;
                        }
                        have_action = 1;
                        if (l != cmdlen) {
                                kprintf("ipfw: opcode %d, action must be"
                                        " last opcode\n",
                                        cmd->opcode);
                                return EINVAL;
                        }
                        break;
                default:
                        kprintf("ipfw: opcode %d, unknown opcode\n",
                                cmd->opcode);
                        return EINVAL;
                }
        }
        if (have_action == 0) {
                kprintf("ipfw: missing action\n");
                return EINVAL;
        }
        return 0;

bad_size:
        kprintf("ipfw: opcode %d size %d wrong\n",
                cmd->opcode, cmdlen);
        return EINVAL;
}

static int
ipfw_ctl_add_rule(struct sockopt *sopt)
{
        struct ipfw_ioc_rule *ioc_rule;
        uint32_t rule_buf[IPFW_RULE_SIZE_MAX];
        size_t size;
        int error;

        ioc_rule = (struct ipfw_ioc_rule *)rule_buf;
        error = sooptcopyin(sopt, ioc_rule, sizeof(rule_buf),
                            sizeof(*ioc_rule));
        if (error)
                return error;

        size = sopt->sopt_valsize;
        error = ipfw_ctl_check_rule(ioc_rule, size);
        if (error)
                return error;

        error = ipfw_add_rule(&layer3_chain, ioc_rule);
        if (error)
                return error;

        if (sopt->sopt_dir == SOPT_GET)
                error = sooptcopyout(sopt, ioc_rule, IOC_RULESIZE(ioc_rule));
        return error;
}

static void *
ipfw_copy_rule(const struct ip_fw *rule, struct ipfw_ioc_rule *ioc_rule)
{
        ioc_rule->act_ofs = rule->act_ofs;
        ioc_rule->cmd_len = rule->cmd_len;
        ioc_rule->rulenum = rule->rulenum;
        ioc_rule->set = rule->set;
        ioc_rule->usr_flags = rule->usr_flags;

        ioc_rule->set_disable = set_disable;
        ioc_rule->static_count = static_count;
        ioc_rule->static_len = static_ioc_len;

        ioc_rule->pcnt = rule->pcnt;
        ioc_rule->bcnt = rule->bcnt;
        ioc_rule->timestamp = rule->timestamp;

        bcopy(rule->cmd, ioc_rule->cmd, ioc_rule->cmd_len * 4 /* XXX */);

        return ((uint8_t *)ioc_rule + IOC_RULESIZE(ioc_rule));
}

static void
ipfw_copy_state(const ipfw_dyn_rule *dyn_rule,
                struct ipfw_ioc_state *ioc_state)
{
        const struct ipfw_flow_id *id;
        struct ipfw_ioc_flowid *ioc_id;

        ioc_state->expire = TIME_LEQ(dyn_rule->expire, time_second) ?
                            0 : dyn_rule->expire - time_second;
        ioc_state->pcnt = dyn_rule->pcnt;
        ioc_state->bcnt = dyn_rule->bcnt;

        ioc_state->dyn_type = dyn_rule->dyn_type;
        ioc_state->count = dyn_rule->count;

        ioc_state->rulenum = dyn_rule->rule->rulenum;

        id = &dyn_rule->id;
        ioc_id = &ioc_state->id;

        ioc_id->type = ETHERTYPE_IP;
        ioc_id->u.ip.dst_ip = id->dst_ip;
        ioc_id->u.ip.src_ip = id->src_ip;
        ioc_id->u.ip.dst_port = id->dst_port;
        ioc_id->u.ip.src_port = id->src_port;
        ioc_id->u.ip.proto = id->proto;
}

static int
ipfw_ctl_get_rules(struct sockopt *sopt)
{
        struct ip_fw *rule;
        void *buf, *bp;
        size_t size;
        int error;

        /*
         * pass up a copy of the current rules. Static rules
         * come first (the last of which has number IPFW_DEFAULT_RULE),
         * followed by a possibly empty list of dynamic rule.
         */
        crit_enter();

        size = static_ioc_len;  /* size of static rules */
        if (ipfw_dyn_v)         /* add size of dyn.rules */
                size += (dyn_count * sizeof(struct ipfw_ioc_state));

        /*
         * XXX todo: if the user passes a short length just to know
         * how much room is needed, do not bother filling up the
         * buffer, just jump to the sooptcopyout.
         */
        bp = buf = kmalloc(size, M_TEMP, M_WAITOK | M_ZERO);

        for (rule = layer3_chain; rule; rule = rule->next)
                bp = ipfw_copy_rule(rule, bp);

        if (ipfw_dyn_v) {
                struct ipfw_ioc_state *ioc_state;
                int i;

                ioc_state = bp;
                for (i = 0; i < curr_dyn_buckets; i++) {
                        ipfw_dyn_rule *p;

                        for (p = ipfw_dyn_v[i]; p != NULL;
                             p = p->next, ioc_state++)
                                ipfw_copy_state(p, ioc_state);
                }
        }

        crit_exit();

        error = sooptcopyout(sopt, buf, size);
        kfree(buf, M_TEMP);
        return error;
}

/**
 * {set|get}sockopt parser.
 */
static int
ipfw_ctl(struct sockopt *sopt)
{
        int error, rulenum;
        uint32_t masks[2];
        size_t size;

        /*
         * Disallow modifications in really-really secure mode, but still allow
         * the logging counters to be reset.
         */
        if (sopt->sopt_name == IP_FW_ADD ||
            (sopt->sopt_dir == SOPT_SET && sopt->sopt_name != IP_FW_RESETLOG)) {
                if (securelevel >= 3)
                        return EPERM;
        }

        error = 0;

        switch (sopt->sopt_name) {
        case IP_FW_GET:
                error = ipfw_ctl_get_rules(sopt);
                break;

        case IP_FW_FLUSH:
                /*
                 * Normally we cannot release the lock on each iteration.
                 * We could do it here only because we start from the head all
                 * the times so there is no risk of missing some entries.
                 * On the other hand, the risk is that we end up with
                 * a very inconsistent ruleset, so better keep the lock
                 * around the whole cycle.
                 *
                 * XXX this code can be improved by resetting the head of
                 * the list to point to the default rule, and then freeing
                 * the old list without the need for a lock.
                 */

                crit_enter();
                free_chain(&layer3_chain, 0 /* keep default rule */);
                crit_exit();
                break;

        case IP_FW_ADD:
                error = ipfw_ctl_add_rule(sopt);
                break;

        case IP_FW_DEL:
                /*
                 * IP_FW_DEL is used for deleting single rules or sets,
                 * and (ab)used to atomically manipulate sets. Argument size
                 * is used to distinguish between the two:
                 *    sizeof(uint32_t)
                 *      delete single rule or set of rules,
                 *      or reassign rules (or sets) to a different set.
                 *    2*sizeof(uint32_t)
                 *      atomic disable/enable sets.
                 *      first uint32_t contains sets to be disabled,
                 *      second uint32_t contains sets to be enabled.
                 */
                error = sooptcopyin(sopt, masks,
                        sizeof(masks), sizeof(masks[0]));
                if (error)
                        break;

                size = sopt->sopt_valsize;
                if (size == sizeof(masks[0])) {
                        /*
                         * Delete or reassign static rule
                         */
                        error = del_entry(&layer3_chain, masks[0]);
                } else if (size == sizeof(masks)) {
                        /*
                         * Set enable/disable
                         */
                        crit_enter();

                        set_disable =
                            (set_disable | masks[0]) & ~masks[1] &
                            ~(1 << 31); /* set 31 always enabled */

                        crit_exit();
                } else {
                        error = EINVAL;
                }
                break;

        case IP_FW_ZERO:
        case IP_FW_RESETLOG: /* argument is an int, the rule number */
                rulenum=0;

                if (sopt->sopt_val != 0) {
                    error = sooptcopyin(sopt, &rulenum,
                            sizeof(int), sizeof(int));
                    if (error)
                        break;
                }
                error = zero_entry(rulenum, sopt->sopt_name == IP_FW_RESETLOG);
                break;

        default:
                kprintf("ipfw_ctl invalid option %d\n", sopt->sopt_name);
                error = EINVAL;
        }

        return error;
}

/*
 * This procedure is only used to handle keepalives. It is invoked
 * every dyn_keepalive_period
 */
static void
ipfw_tick(void * __unused unused)
{
        int i;
        ipfw_dyn_rule *q;

        if (dyn_keepalive == 0 || ipfw_dyn_v == NULL || dyn_count == 0)
                goto done;

        crit_enter();
        for (i = 0 ; i < curr_dyn_buckets ; i++) {
                for (q = ipfw_dyn_v[i] ; q ; q = q->next ) {
                        if (q->dyn_type == O_LIMIT_PARENT)
                                continue;
                        if (q->id.proto != IPPROTO_TCP)
                                continue;
                        if ( (q->state & BOTH_SYN) != BOTH_SYN)
                                continue;
                        if (TIME_LEQ( time_second+dyn_keepalive_interval,
                            q->expire))
                                continue;       /* too early */
                        if (TIME_LEQ(q->expire, time_second))
                                continue;       /* too late, rule expired */

                        send_pkt(&(q->id), q->ack_rev - 1, q->ack_fwd, TH_SYN);
                        send_pkt(&(q->id), q->ack_fwd - 1, q->ack_rev, 0);
                }
        }
        crit_exit();
done:
        callout_reset(&ipfw_timeout_h, dyn_keepalive_period * hz,
                      ipfw_tick, NULL);
}

static void
ipfw_init_default_rule(struct ip_fw **head)
{
        struct ip_fw *def_rule;

        KKASSERT(*head == NULL);

        def_rule = kmalloc(sizeof(*def_rule), M_IPFW, M_WAITOK | M_ZERO);

        def_rule->act_ofs = 0;
        def_rule->rulenum = IPFW_DEFAULT_RULE;
        def_rule->cmd_len = 1;
        def_rule->set = 31;

        def_rule->cmd[0].len = 1;
#ifdef IPFIREWALL_DEFAULT_TO_ACCEPT
        def_rule->cmd[0].opcode = O_ACCEPT;
#else
        def_rule->cmd[0].opcode = O_DENY;
#endif

        def_rule->refcnt = 1;

        *head = def_rule;
        ipfw_inc_static_count(def_rule);

        /* Install the default rule */
        ip_fw_default_rule = def_rule;
}

static void
ipfw_init(void)
{
        ip_fw_chk_ptr = ipfw_chk;
        ip_fw_ctl_ptr = ipfw_ctl;
        ip_fw_dn_io_ptr = ipfw_dummynet_io;

        layer3_chain = NULL;
        ipfw_init_default_rule(&layer3_chain);

        kprintf("ipfw2 initialized, divert %s, "
                "rule-based forwarding enabled, default to %s, logging ",
#ifdef IPDIVERT
                "enabled",
#else
                "disabled",
#endif
                ip_fw_default_rule->cmd[0].opcode == O_ACCEPT ?
                "accept" : "deny");

#ifdef IPFIREWALL_VERBOSE
        fw_verbose = 1;
#endif
#ifdef IPFIREWALL_VERBOSE_LIMIT
        verbose_limit = IPFIREWALL_VERBOSE_LIMIT;
#endif
        if (fw_verbose == 0)
                kprintf("disabled\n");
        else if (verbose_limit == 0)
                kprintf("unlimited\n");
        else
                kprintf("limited to %d packets/entry by default\n",
                    verbose_limit);
        callout_init(&ipfw_timeout_h);
        callout_reset(&ipfw_timeout_h, hz, ipfw_tick, NULL);
}

static int
ipfw_modevent(module_t mod, int type, void *unused)
{
        int err = 0;

        switch (type) {
        case MOD_LOAD:
                crit_enter();
                if (IPFW_LOADED) {
                        crit_exit();
                        kprintf("IP firewall already loaded\n");
                        err = EEXIST;
                } else {
                        ipfw_init();
                        crit_exit();
                }
                break;

        case MOD_UNLOAD:
#ifndef KLD_MODULE
                kprintf("ipfw statically compiled, cannot unload\n");
                err = EBUSY;
#else
                if (ipfw_refcnt != 0) {
                        err = EBUSY;
                        break;
                }

                crit_enter();
                callout_stop(&ipfw_timeout_h);
                ip_fw_chk_ptr = NULL;
                ip_fw_ctl_ptr = NULL;
                ip_fw_dn_io_ptr = NULL;
                free_chain(&layer3_chain, 1 /* kill default rule */);
                crit_exit();
                kprintf("IP firewall unloaded\n");
#endif
                break;
        default:
                break;
        }
        return err;
}

static moduledata_t ipfwmod = {
        "ipfw",
        ipfw_modevent,
        0
};
DECLARE_MODULE(ipfw, ipfwmod, SI_SUB_PROTO_END, SI_ORDER_ANY);
MODULE_VERSION(ipfw, 1);