/*      $NetBSD: udp_usrreq.c,v 1.266 2024/10/08 02:30:04 riastradh Exp $       */

/*
 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the project nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE PROJECT 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 PROJECT 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.
 */

/*
 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
 *
 *      @(#)udp_usrreq.c        8.6 (Berkeley) 5/23/95
 */

/*
 * UDP protocol implementation.
 * Per RFC 768, August, 1980.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: udp_usrreq.c,v 1.266 2024/10/08 02:30:04 riastradh Exp $");

#ifdef _KERNEL_OPT
#include "opt_inet.h"
#include "opt_ipsec.h"
#include "opt_inet_csum.h"
#include "opt_mbuftrace.h"
#include "opt_net_mpsafe.h"
#endif

#include <sys/param.h>
#include <sys/mbuf.h>
#include <sys/once.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/domain.h>
#include <sys/sysctl.h>

#include <net/if.h>

#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/in_var.h>
#include <netinet/ip.h>
#include <netinet/in_pcb.h>
#include <netinet/ip_var.h>
#include <netinet/ip_icmp.h>
#include <netinet/udp.h>
#include <netinet/udp_var.h>
#include <netinet/udp_private.h>

#ifdef INET6
#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>
#include <netinet6/ip6_private.h>
#include <netinet6/in6_pcb.h>
#include <netinet6/udp6_var.h>
#include <netinet6/udp6_private.h>
#endif

#ifndef INET6
#include <netinet/ip6.h>
#endif

#ifdef IPSEC
#include <netipsec/ipsec.h>
#include <netipsec/esp.h>
#endif

int udpcksum = 1;
int udp_do_loopback_cksum = 0;

struct inpcbtable udbtable;

percpu_t *udpstat_percpu;

#ifdef INET
#ifdef IPSEC
static int udp4_espinudp(struct mbuf **, int);
#endif
static void udp4_sendup(struct mbuf *, int, struct sockaddr *,
    struct socket *);
static int udp4_realinput(struct sockaddr_in *, struct sockaddr_in *,
    struct mbuf **, int);
static int udp4_input_checksum(struct mbuf *, const struct udphdr *, int, int);
#endif
#ifdef INET
static void udp_notify (struct inpcb *, int);
#endif

#ifndef UDBHASHSIZE
#define UDBHASHSIZE     128
#endif
int udbhashsize = UDBHASHSIZE;

/*
 * For send - really max datagram size; for receive - 40 1K datagrams.
 */
static int udp_sendspace = 9216;
static int udp_recvspace = 40 * (1024 + sizeof(struct sockaddr_in));

#ifdef MBUFTRACE
struct mowner udp_mowner = MOWNER_INIT("udp", "");
struct mowner udp_rx_mowner = MOWNER_INIT("udp", "rx");
struct mowner udp_tx_mowner = MOWNER_INIT("udp", "tx");
#endif

#ifdef UDP_CSUM_COUNTERS
#include <sys/device.h>

#if defined(INET)
struct evcnt udp_hwcsum_bad = EVCNT_INITIALIZER(EVCNT_TYPE_MISC,
    NULL, "udp", "hwcsum bad");
struct evcnt udp_hwcsum_ok = EVCNT_INITIALIZER(EVCNT_TYPE_MISC,
    NULL, "udp", "hwcsum ok");
struct evcnt udp_hwcsum_data = EVCNT_INITIALIZER(EVCNT_TYPE_MISC,
    NULL, "udp", "hwcsum data");
struct evcnt udp_swcsum = EVCNT_INITIALIZER(EVCNT_TYPE_MISC,
    NULL, "udp", "swcsum");

EVCNT_ATTACH_STATIC(udp_hwcsum_bad);
EVCNT_ATTACH_STATIC(udp_hwcsum_ok);
EVCNT_ATTACH_STATIC(udp_hwcsum_data);
EVCNT_ATTACH_STATIC(udp_swcsum);
#endif /* defined(INET) */

#define UDP_CSUM_COUNTER_INCR(ev)       (ev)->ev_count++
#else
#define UDP_CSUM_COUNTER_INCR(ev)       /* nothing */
#endif /* UDP_CSUM_COUNTERS */

static void sysctl_net_inet_udp_setup(struct sysctllog **);

static int
do_udpinit(void)
{

        inpcb_init(&udbtable, udbhashsize, udbhashsize);
        udpstat_percpu = percpu_alloc(sizeof(uint64_t) * UDP_NSTATS);

        MOWNER_ATTACH(&udp_tx_mowner);
        MOWNER_ATTACH(&udp_rx_mowner);
        MOWNER_ATTACH(&udp_mowner);

        return 0;
}

void
udp_init_common(void)
{
        static ONCE_DECL(doudpinit);

        RUN_ONCE(&doudpinit, do_udpinit);
}

void
udp_init(void)
{

        sysctl_net_inet_udp_setup(NULL);

        udp_init_common();
}

/*
 * Checksum extended UDP header and data.
 */
int
udp_input_checksum(int af, struct mbuf *m, const struct udphdr *uh,
    int iphlen, int len)
{

        switch (af) {
#ifdef INET
        case AF_INET:
                return udp4_input_checksum(m, uh, iphlen, len);
#endif
#ifdef INET6
        case AF_INET6:
                return udp6_input_checksum(m, uh, iphlen, len);
#endif
        }
#ifdef DIAGNOSTIC
        panic("udp_input_checksum: unknown af %d", af);
#endif
        /* NOTREACHED */
        return -1;
}

#ifdef INET

/*
 * Checksum extended UDP header and data.
 */
static int
udp4_input_checksum(struct mbuf *m, const struct udphdr *uh,
    int iphlen, int len)
{

        /*
         * XXX it's better to record and check if this mbuf is
         * already checked.
         */

        if (uh->uh_sum == 0)
                return 0;

        switch (m->m_pkthdr.csum_flags &
            ((m_get_rcvif_NOMPSAFE(m)->if_csum_flags_rx & M_CSUM_UDPv4) |
            M_CSUM_TCP_UDP_BAD | M_CSUM_DATA)) {
        case M_CSUM_UDPv4|M_CSUM_TCP_UDP_BAD:
                UDP_CSUM_COUNTER_INCR(&udp_hwcsum_bad);
                goto badcsum;

        case M_CSUM_UDPv4|M_CSUM_DATA: {
                u_int32_t hw_csum = m->m_pkthdr.csum_data;

                UDP_CSUM_COUNTER_INCR(&udp_hwcsum_data);
                if (m->m_pkthdr.csum_flags & M_CSUM_NO_PSEUDOHDR) {
                        const struct ip *ip =
                            mtod(m, const struct ip *);

                        hw_csum = in_cksum_phdr(ip->ip_src.s_addr,
                            ip->ip_dst.s_addr,
                            htons(hw_csum + len + IPPROTO_UDP));
                }
                if ((hw_csum ^ 0xffff) != 0)
                        goto badcsum;
                break;
        }

        case M_CSUM_UDPv4:
                /* Checksum was okay. */
                UDP_CSUM_COUNTER_INCR(&udp_hwcsum_ok);
                break;

        default:
                /*
                 * Need to compute it ourselves.  Maybe skip checksum
                 * on loopback interfaces.
                 */
                if (__predict_true(!(m_get_rcvif_NOMPSAFE(m)->if_flags &
                                     IFF_LOOPBACK) ||
                                   udp_do_loopback_cksum)) {
                        UDP_CSUM_COUNTER_INCR(&udp_swcsum);
                        if (in4_cksum(m, IPPROTO_UDP, iphlen, len) != 0)
                                goto badcsum;
                }
                break;
        }

        return 0;

badcsum:
        UDP_STATINC(UDP_STAT_BADSUM);
        return -1;
}

void
udp_input(struct mbuf *m, int off, int proto)
{
        struct sockaddr_in src, dst;
        struct ip *ip;
        struct udphdr *uh;
        int iphlen = off;
        int len;
        int n;
        u_int16_t ip_len;

        MCLAIM(m, &udp_rx_mowner);
        UDP_STATINC(UDP_STAT_IPACKETS);

        /*
         * Get IP and UDP header together in first mbuf.
         */
        ip = mtod(m, struct ip *);
        M_REGION_GET(uh, struct udphdr *, m, iphlen, sizeof(struct udphdr));
        if (uh == NULL) {
                UDP_STATINC(UDP_STAT_HDROPS);
                return;
        }

        /*
         * Enforce alignment requirements that are violated in
         * some cases, see kern/50766 for details.
         */
        if (ACCESSIBLE_POINTER(uh, struct udphdr) == 0) {
                m = m_copyup(m, iphlen + sizeof(struct udphdr), 0);
                if (m == NULL) {
                        UDP_STATINC(UDP_STAT_HDROPS);
                        return;
                }
                ip = mtod(m, struct ip *);
                uh = (struct udphdr *)(mtod(m, char *) + iphlen);
        }
        KASSERT(ACCESSIBLE_POINTER(uh, struct udphdr));

        /* destination port of 0 is illegal, based on RFC768. */
        if (uh->uh_dport == 0)
                goto bad;

        /*
         * Make mbuf data length reflect UDP length.
         * If not enough data to reflect UDP length, drop.
         */
        ip_len = ntohs(ip->ip_len);
        len = ntohs((u_int16_t)uh->uh_ulen);
        if (len < sizeof(struct udphdr)) {
                UDP_STATINC(UDP_STAT_BADLEN);
                goto bad;
        }
        if (ip_len != iphlen + len) {
                if (ip_len < iphlen + len) {
                        UDP_STATINC(UDP_STAT_BADLEN);
                        goto bad;
                }
                m_adj(m, iphlen + len - ip_len);
        }

        /*
         * Checksum extended UDP header and data.
         */
        if (udp4_input_checksum(m, uh, iphlen, len))
                goto badcsum;

        /* construct source and dst sockaddrs. */
        sockaddr_in_init(&src, &ip->ip_src, uh->uh_sport);
        sockaddr_in_init(&dst, &ip->ip_dst, uh->uh_dport);

        if ((n = udp4_realinput(&src, &dst, &m, iphlen)) == -1) {
                UDP_STATINC(UDP_STAT_HDROPS);
                return;
        }
        if (m == NULL) {
                /*
                 * packet has been processed by ESP stuff -
                 * e.g. dropped NAT-T-keep-alive-packet ...
                 */
                return;
        }

        ip = mtod(m, struct ip *);
        M_REGION_GET(uh, struct udphdr *, m, iphlen, sizeof(struct udphdr));
        if (uh == NULL) {
                UDP_STATINC(UDP_STAT_HDROPS);
                return;
        }
        /* XXX Re-enforce alignment? */

#ifdef INET6
        if (IN_MULTICAST(ip->ip_dst.s_addr) || n == 0) {
                struct sockaddr_in6 src6, dst6;

                memset(&src6, 0, sizeof(src6));
                src6.sin6_family = AF_INET6;
                src6.sin6_len = sizeof(struct sockaddr_in6);
                in6_in_2_v4mapin6(&ip->ip_src, &src6.sin6_addr);
                src6.sin6_port = uh->uh_sport;
                memset(&dst6, 0, sizeof(dst6));
                dst6.sin6_family = AF_INET6;
                dst6.sin6_len = sizeof(struct sockaddr_in6);
                in6_in_2_v4mapin6(&ip->ip_dst, &dst6.sin6_addr);
                dst6.sin6_port = uh->uh_dport;

                n += udp6_realinput(AF_INET, &src6, &dst6, &m, iphlen);
        }
#endif

        if (n == 0) {
                if (m->m_flags & (M_BCAST | M_MCAST)) {
                        UDP_STATINC(UDP_STAT_NOPORTBCAST);
                        goto bad;
                }
                UDP_STATINC(UDP_STAT_NOPORT);
                icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_PORT, 0, 0);
                m = NULL;
        }

bad:
        m_freem(m);
        return;

badcsum:
        m_freem(m);
}
#endif

#ifdef INET
static void
udp4_sendup(struct mbuf *m, int off /* offset of data portion */,
    struct sockaddr *src, struct socket *so)
{
        struct mbuf *opts = NULL;
        struct mbuf *n;
        struct inpcb *inp;

        KASSERT(so != NULL);
        KASSERT(so->so_proto->pr_domain->dom_family == AF_INET);
        inp = sotoinpcb(so);
        KASSERT(inp != NULL);

#if defined(IPSEC)
        if (ipsec_used && ipsec_in_reject(m, inp)) {
                if ((n = m_copypacket(m, M_DONTWAIT)) != NULL)
                        icmp_error(n, ICMP_UNREACH, ICMP_UNREACH_ADMIN_PROHIBIT,
                            0, 0);
                return;
        }
#endif

        if ((n = m_copypacket(m, M_DONTWAIT)) != NULL) {
                if (inp->inp_flags & INP_CONTROLOPTS ||
                    SOOPT_TIMESTAMP(so->so_options)) {
                        struct ip *ip = mtod(n, struct ip *);
                        ip_savecontrol(inp, &opts, ip, n);
                }

                m_adj(n, off);
                if (sbappendaddr(&so->so_rcv, src, n, opts) == 0) {
                        m_freem(n);
                        m_freem(opts);
                        UDP_STATINC(UDP_STAT_FULLSOCK);
                        soroverflow(so);
                } else
                        sorwakeup(so);
        }
}
#endif

#ifdef INET
static int
udp4_realinput(struct sockaddr_in *src, struct sockaddr_in *dst,
    struct mbuf **mp, int off /* offset of udphdr */)
{
        u_int16_t *sport, *dport;
        int rcvcnt;
        struct in_addr *src4, *dst4;
        struct inpcb *inp;
        struct mbuf *m = *mp;

        rcvcnt = 0;
        off += sizeof(struct udphdr);   /* now, offset of payload */

        if (src->sin_family != AF_INET || dst->sin_family != AF_INET)
                goto bad;

        src4 = &src->sin_addr;
        sport = &src->sin_port;
        dst4 = &dst->sin_addr;
        dport = &dst->sin_port;

        if (IN_MULTICAST(dst4->s_addr) ||
            in_broadcast(*dst4, m_get_rcvif_NOMPSAFE(m))) {
                /*
                 * Deliver a multicast or broadcast datagram to *all* sockets
                 * for which the local and remote addresses and ports match
                 * those of the incoming datagram.  This allows more than
                 * one process to receive multi/broadcasts on the same port.
                 * (This really ought to be done for unicast datagrams as
                 * well, but that would cause problems with existing
                 * applications that open both address-specific sockets and
                 * a wildcard socket listening to the same port -- they would
                 * end up receiving duplicates of every unicast datagram.
                 * Those applications open the multiple sockets to overcome an
                 * inadequacy of the UDP socket interface, but for backwards
                 * compatibility we avoid the problem here rather than
                 * fixing the interface.  Maybe 4.5BSD will remedy this?)
                 */

                /*
                 * KAME note: traditionally we dropped udpiphdr from mbuf here.
                 * we need udpiphdr for IPsec processing so we do that later.
                 */
                /*
                 * Locate pcb(s) for datagram.
                 */
                TAILQ_FOREACH(inp, &udbtable.inpt_queue, inp_queue) {
                        if (inp->inp_af != AF_INET)
                                continue;

                        if (inp->inp_lport != *dport)
                                continue;
                        if (!in_nullhost(in4p_laddr(inp))) {
                                if (!in_hosteq(in4p_laddr(inp), *dst4))
                                        continue;
                        }
                        if (!in_nullhost(in4p_faddr(inp))) {
                                if (!in_hosteq(in4p_faddr(inp), *src4) ||
                                    inp->inp_fport != *sport)
                                        continue;
                        }

                        udp4_sendup(m, off, (struct sockaddr *)src,
                            inp->inp_socket);
                        rcvcnt++;

                        /*
                         * Don't look for additional matches if this one does
                         * not have either the SO_REUSEPORT or SO_REUSEADDR
                         * socket options set.  This heuristic avoids searching
                         * through all pcbs in the common case of a non-shared
                         * port.  It assumes that an application will never
                         * clear these options after setting them.
                         */
                        if ((inp->inp_socket->so_options &
                            (SO_REUSEPORT|SO_REUSEADDR)) == 0)
                                break;
                }
        } else {
                /*
                 * Locate pcb for datagram.
                 */
                inp = inpcb_lookup(&udbtable, *src4, *sport, *dst4,
                    *dport, 0);
                if (inp == 0) {
                        UDP_STATINC(UDP_STAT_PCBHASHMISS);
                        inp = inpcb_lookup_bound(&udbtable, *dst4, *dport);
                        if (inp == 0)
                                return rcvcnt;
                }

#ifdef IPSEC
                /* Handle ESP over UDP */
                if (inp->inp_flags & INP_ESPINUDP) {
                        switch (udp4_espinudp(mp, off)) {
                        case -1: /* Error, m was freed */
                                KASSERT(*mp == NULL);
                                rcvcnt = -1;
                                goto bad;

                        case 1: /* ESP over UDP */
                                KASSERT(*mp == NULL);
                                rcvcnt++;
                                goto bad;

                        case 0: /* plain UDP */
                        default: /* Unexpected */
                                /*
                                 * Normal UDP processing will take place,
                                 * m may have changed.
                                 */
                                m = *mp;
                                break;
                        }
                }
#endif
                if (inp->inp_overudp_cb != NULL) {
                        int ret;
                        ret = inp->inp_overudp_cb(mp, off, inp->inp_socket,
                            sintosa(src), inp->inp_overudp_arg);
                        switch (ret) {
                        case -1: /* Error, m was freed */
                                KASSERT(*mp == NULL);
                                rcvcnt = -1;
                                goto bad;

                        case 1: /* Foo over UDP */
                                KASSERT(*mp == NULL);
                                rcvcnt++;
                                goto bad;

                        case 0: /* plain UDP */
                        default: /* Unexpected */
                                /*
                                 * Normal UDP processing will take place,
                                 * m may have changed.
                                 */
                                m = *mp;
                                break;
                        }
                }

                /*
                 * Check the minimum TTL for socket.
                 */
                if (mtod(m, struct ip *)->ip_ttl < in4p_ip_minttl(inp))
                        goto bad;

                udp4_sendup(m, off, (struct sockaddr *)src, inp->inp_socket);
                rcvcnt++;
        }

bad:
        return rcvcnt;
}
#endif

#ifdef INET
/*
 * Notify a udp user of an asynchronous error;
 * just wake up so that he can collect error status.
 */
static void
udp_notify(struct inpcb *inp, int errno)
{
        inp->inp_socket->so_error = errno;
        sorwakeup(inp->inp_socket);
        sowwakeup(inp->inp_socket);
}

void *
udp_ctlinput(int cmd, const struct sockaddr *sa, void *v)
{
        struct ip *ip = v;
        struct udphdr *uh;
        void (*notify)(struct inpcb *, int) = udp_notify;
        int errno;

        if (sa->sa_family != AF_INET ||
            sa->sa_len != sizeof(struct sockaddr_in))
                return NULL;
        if ((unsigned)cmd >= PRC_NCMDS)
                return NULL;

        errno = inetctlerrmap[cmd];
        if (PRC_IS_REDIRECT(cmd)) {
                notify = inpcb_rtchange;
                ip = NULL;
        } else if (cmd == PRC_HOSTDEAD) {
                ip = NULL;
        } else if (errno == 0) {
                return NULL;
        }

        if (ip) {
                uh = (struct udphdr *)((char *)ip + (ip->ip_hl << 2));
                inpcb_notify(&udbtable, satocsin(sa)->sin_addr, uh->uh_dport,
                    ip->ip_src, uh->uh_sport, errno, notify);
                /* XXX mapped address case */
        } else {
                inpcb_notifyall(&udbtable, satocsin(sa)->sin_addr, errno,
                    notify);
        }

        return NULL;
}

int
udp_ctloutput(int op, struct socket *so, struct sockopt *sopt)
{
        int s;
        int error = 0;
        struct inpcb *inp;
        int family;
        int optval;

        family = so->so_proto->pr_domain->dom_family;

        s = splsoftnet();
        switch (family) {
#ifdef INET
        case PF_INET:
                if (sopt->sopt_level != IPPROTO_UDP) {
                        error = ip_ctloutput(op, so, sopt);
                        goto end;
                }
                break;
#endif
#ifdef INET6
        case PF_INET6:
                if (sopt->sopt_level != IPPROTO_UDP) {
                        error = ip6_ctloutput(op, so, sopt);
                        goto end;
                }
                break;
#endif
        default:
                error = EAFNOSUPPORT;
                goto end;
        }


        switch (op) {
        case PRCO_SETOPT:
                inp = sotoinpcb(so);

                switch (sopt->sopt_name) {
                case UDP_ENCAP:
                        error = sockopt_getint(sopt, &optval);
                        if (error)
                                break;

                        switch(optval) {
                        case 0:
                                inp->inp_flags &= ~INP_ESPINUDP;
                                break;

                        case UDP_ENCAP_ESPINUDP:
                                inp->inp_flags |= INP_ESPINUDP;
                                break;

                        default:
                                error = EINVAL;
                                break;
                        }
                        break;

                default:
                        error = ENOPROTOOPT;
                        break;
                }
                break;

        default:
                error = EINVAL;
                break;
        }

end:
        splx(s);
        return error;
}

int
udp_output(struct mbuf *m, struct inpcb *inp, struct mbuf *control,
    struct lwp *l)
{
        struct udpiphdr *ui;
        struct route *ro;
        struct ip_pktopts pktopts;
        kauth_cred_t cred;
        int len = m->m_pkthdr.len;
        int error, flags = 0;

        MCLAIM(m, &udp_tx_mowner);

        /*
         * Calculate data length and get a mbuf
         * for UDP and IP headers.
         */
        M_PREPEND(m, sizeof(struct udpiphdr), M_DONTWAIT);
        if (m == NULL) {
                error = ENOBUFS;
                goto release;
        }

        /*
         * Compute the packet length of the IP header, and
         * punt if the length looks bogus.
         */
        if (len + sizeof(struct udpiphdr) > IP_MAXPACKET) {
                error = EMSGSIZE;
                goto release;
        }

        if (l == NULL)
                cred = NULL;
        else
                cred = l->l_cred;

        /* Setup IP outgoing packet options */
        memset(&pktopts, 0, sizeof(pktopts));
        error = ip_setpktopts(control, &pktopts, &flags, inp, cred);
        if (error != 0)
                goto release;

        m_freem(control);
        control = NULL;

        /*
         * Fill in mbuf with extended UDP header
         * and addresses and length put into network format.
         */
        ui = mtod(m, struct udpiphdr *);
        ui->ui_pr = IPPROTO_UDP;
        ui->ui_src = pktopts.ippo_laddr.sin_addr;
        ui->ui_dst = in4p_faddr(inp);
        ui->ui_sport = inp->inp_lport;
        ui->ui_dport = inp->inp_fport;
        ui->ui_ulen = htons((u_int16_t)len + sizeof(struct udphdr));

        ro = &inp->inp_route;

        /*
         * Set up checksum and output datagram.
         */
        if (udpcksum) {
                /*
                 * XXX Cache pseudo-header checksum part for
                 * XXX "connected" UDP sockets.
                 */
                ui->ui_sum = in_cksum_phdr(ui->ui_src.s_addr,
                    ui->ui_dst.s_addr, htons((u_int16_t)len +
                    sizeof(struct udphdr) + IPPROTO_UDP));
                m->m_pkthdr.csum_flags = M_CSUM_UDPv4;
                m->m_pkthdr.csum_data = offsetof(struct udphdr, uh_sum);
        } else
                ui->ui_sum = 0;

        ((struct ip *)ui)->ip_len = htons(sizeof(struct udpiphdr) + len);
        ((struct ip *)ui)->ip_ttl = in4p_ip(inp).ip_ttl;        /* XXX */
        ((struct ip *)ui)->ip_tos = in4p_ip(inp).ip_tos;        /* XXX */
        UDP_STATINC(UDP_STAT_OPACKETS);

        flags |= inp->inp_socket->so_options & (SO_DONTROUTE|SO_BROADCAST);
        return ip_output(m, inp->inp_options, ro, flags, pktopts.ippo_imo, inp);

 release:
        m_freem(control);
        m_freem(m);
        return error;
}

static int
udp_attach(struct socket *so, int proto)
{
        struct inpcb *inp;
        int error;

        KASSERT(sotoinpcb(so) == NULL);

        /* Assign the lock (must happen even if we will error out). */
        sosetlock(so);

#ifdef MBUFTRACE
        so->so_mowner = &udp_mowner;
        so->so_rcv.sb_mowner = &udp_rx_mowner;
        so->so_snd.sb_mowner = &udp_tx_mowner;
#endif
        if (so->so_snd.sb_hiwat == 0 || so->so_rcv.sb_hiwat == 0) {
                error = soreserve(so, udp_sendspace, udp_recvspace);
                if (error) {
                        return error;
                }
        }

        error = inpcb_create(so, &udbtable);
        if (error) {
                return error;
        }
        inp = sotoinpcb(so);
        in4p_ip(inp).ip_ttl = ip_defttl;
        KASSERT(solocked(so));

        return error;
}

static void
udp_detach(struct socket *so)
{
        struct inpcb *inp;

        KASSERT(solocked(so));
        inp = sotoinpcb(so);
        KASSERT(inp != NULL);
        inpcb_destroy(inp);
}

static int
udp_accept(struct socket *so, struct sockaddr *nam)
{
        KASSERT(solocked(so));

        panic("udp_accept");

        return EOPNOTSUPP;
}

static int
udp_bind(struct socket *so, struct sockaddr *nam, struct lwp *l)
{
        struct inpcb *inp = sotoinpcb(so);
        struct sockaddr_in *sin = (struct sockaddr_in *)nam;
        int error = 0;
        int s;

        KASSERT(solocked(so));
        KASSERT(inp != NULL);
        KASSERT(nam != NULL);

        s = splsoftnet();
        error = inpcb_bind(inp, sin, l);
        splx(s);

        return error;
}

static int
udp_listen(struct socket *so, struct lwp *l)
{
        KASSERT(solocked(so));

        return EOPNOTSUPP;
}

static int
udp_connect(struct socket *so, struct sockaddr *nam, struct lwp *l)
{
        struct inpcb *inp = sotoinpcb(so);
        int error = 0;
        int s;

        KASSERT(solocked(so));
        KASSERT(inp != NULL);
        KASSERT(nam != NULL);

        s = splsoftnet();
        error = inpcb_connect(inp, (struct sockaddr_in *)nam, l);
        if (! error)
                soisconnected(so);
        splx(s);
        return error;
}

static int
udp_connect2(struct socket *so, struct socket *so2)
{
        KASSERT(solocked(so));

        return EOPNOTSUPP;
}

static int
udp_disconnect(struct socket *so)
{
        struct inpcb *inp = sotoinpcb(so);
        int s;

        KASSERT(solocked(so));
        KASSERT(inp != NULL);

        s = splsoftnet();
        /*soisdisconnected(so);*/
        so->so_state &= ~SS_ISCONNECTED;        /* XXX */
        inpcb_disconnect(inp);
        in4p_laddr(inp) = zeroin_addr;          /* XXX */
        inpcb_set_state(inp, INP_BOUND);                /* XXX */
        splx(s);

        return 0;
}

static int
udp_shutdown(struct socket *so)
{
        int s;

        KASSERT(solocked(so));

        s = splsoftnet();
        socantsendmore(so);
        splx(s);

        return 0;
}

static int
udp_abort(struct socket *so)
{
        KASSERT(solocked(so));

        panic("udp_abort");

        return EOPNOTSUPP;
}

static int
udp_ioctl(struct socket *so, u_long cmd, void *nam, struct ifnet *ifp)
{
        return in_control(so, cmd, nam, ifp);
}

static int
udp_stat(struct socket *so, struct stat *ub)
{
        KASSERT(solocked(so));

        /* stat: don't bother with a blocksize. */
        return 0;
}

static int
udp_peeraddr(struct socket *so, struct sockaddr *nam)
{
        int s;

        KASSERT(solocked(so));
        KASSERT(sotoinpcb(so) != NULL);
        KASSERT(nam != NULL);

        s = splsoftnet();
        inpcb_fetch_peeraddr(sotoinpcb(so), (struct sockaddr_in *)nam);
        splx(s);

        return 0;
}

static int
udp_sockaddr(struct socket *so, struct sockaddr *nam)
{
        int s;

        KASSERT(solocked(so));
        KASSERT(sotoinpcb(so) != NULL);
        KASSERT(nam != NULL);

        s = splsoftnet();
        inpcb_fetch_sockaddr(sotoinpcb(so), (struct sockaddr_in *)nam);
        splx(s);

        return 0;
}

static int
udp_rcvd(struct socket *so, int flags, struct lwp *l)
{
        KASSERT(solocked(so));

        return EOPNOTSUPP;
}

static int
udp_recvoob(struct socket *so, struct mbuf *m, int flags)
{
        KASSERT(solocked(so));

        return EOPNOTSUPP;
}

int
udp_send(struct socket *so, struct mbuf *m, struct sockaddr *nam,
    struct mbuf *control, struct lwp *l)
{
        struct inpcb *inp = sotoinpcb(so);
        int error = 0;
        struct in_addr laddr;                   /* XXX */
        int s;

        KASSERT(solocked(so));
        KASSERT(inp != NULL);
        KASSERT(m != NULL);

        memset(&laddr, 0, sizeof laddr);

        s = splsoftnet();
        if (nam) {
                laddr = in4p_laddr(inp);                /* XXX */
                if ((so->so_state & SS_ISCONNECTED) != 0) {
                        error = EISCONN;
                        goto die;
                }
                error = inpcb_connect(inp, (struct sockaddr_in *)nam, l);
                if (error)
                        goto die;
        } else {
                if ((so->so_state & SS_ISCONNECTED) == 0) {
                        error = ENOTCONN;
                        goto die;
                }
        }
        error = udp_output(m, inp, control, l);
        m = NULL;
        control = NULL;
        if (nam) {
                inpcb_disconnect(inp);
                in4p_laddr(inp) = laddr;                /* XXX */
                inpcb_set_state(inp, INP_BOUND);        /* XXX */
        }
  die:
        m_freem(m);
        m_freem(control);

        splx(s);
        return error;
}

static int
udp_sendoob(struct socket *so, struct mbuf *m, struct mbuf *control)
{
        KASSERT(solocked(so));

        m_freem(m);
        m_freem(control);

        return EOPNOTSUPP;
}

static int
udp_purgeif(struct socket *so, struct ifnet *ifp)
{
        int s;

        s = splsoftnet();
        mutex_enter(softnet_lock);
        inpcb_purgeif0(&udbtable, ifp);
#ifdef NET_MPSAFE
        mutex_exit(softnet_lock);
#endif
        in_purgeif(ifp);
#ifdef NET_MPSAFE
        mutex_enter(softnet_lock);
#endif
        inpcb_purgeif(&udbtable, ifp);
        mutex_exit(softnet_lock);
        splx(s);

        return 0;
}

static int
sysctl_net_inet_udp_stats(SYSCTLFN_ARGS)
{

        return (NETSTAT_SYSCTL(udpstat_percpu, UDP_NSTATS));
}

/*
 * Sysctl for udp variables.
 */
static void
sysctl_net_inet_udp_setup(struct sysctllog **clog)
{

        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_NODE, "inet", NULL,
                       NULL, 0, NULL, 0,
                       CTL_NET, PF_INET, CTL_EOL);
        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_NODE, "udp",
                       SYSCTL_DESCR("UDPv4 related settings"),
                       NULL, 0, NULL, 0,
                       CTL_NET, PF_INET, IPPROTO_UDP, CTL_EOL);

        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                       CTLTYPE_INT, "checksum",
                       SYSCTL_DESCR("Compute UDP checksums"),
                       NULL, 0, &udpcksum, 0,
                       CTL_NET, PF_INET, IPPROTO_UDP, UDPCTL_CHECKSUM,
                       CTL_EOL);
        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                       CTLTYPE_INT, "sendspace",
                       SYSCTL_DESCR("Default UDP send buffer size"),
                       NULL, 0, &udp_sendspace, 0,
                       CTL_NET, PF_INET, IPPROTO_UDP, UDPCTL_SENDSPACE,
                       CTL_EOL);
        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                       CTLTYPE_INT, "recvspace",
                       SYSCTL_DESCR("Default UDP receive buffer size"),
                       NULL, 0, &udp_recvspace, 0,
                       CTL_NET, PF_INET, IPPROTO_UDP, UDPCTL_RECVSPACE,
                       CTL_EOL);
        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                       CTLTYPE_INT, "do_loopback_cksum",
                       SYSCTL_DESCR("Perform UDP checksum on loopback"),
                       NULL, 0, &udp_do_loopback_cksum, 0,
                       CTL_NET, PF_INET, IPPROTO_UDP, UDPCTL_LOOPBACKCKSUM,
                       CTL_EOL);
        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_STRUCT, "pcblist",
                       SYSCTL_DESCR("UDP protocol control block list"),
                       sysctl_inpcblist, 0, &udbtable, 0,
                       CTL_NET, PF_INET, IPPROTO_UDP, CTL_CREATE,
                       CTL_EOL);
        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_STRUCT, "stats",
                       SYSCTL_DESCR("UDP statistics"),
                       sysctl_net_inet_udp_stats, 0, NULL, 0,
                       CTL_NET, PF_INET, IPPROTO_UDP, UDPCTL_STATS,
                       CTL_EOL);
}
#endif

void
udp_statinc(u_int stat)
{

        KASSERT(stat < UDP_NSTATS);
        UDP_STATINC(stat);
}

#if defined(INET) && defined(IPSEC)
/*
 * Handle ESP-in-UDP packets (RFC3948).
 *
 * We need to distinguish between ESP packets and IKE packets. We do so by
 * looking at the Non-ESP marker. If IKE, we process the UDP packet as usual.
 * Otherwise, ESP, we invoke IPsec.
 *
 * Returns:
 *     1 if the packet was processed
 *     0 if normal UDP processing should take place
 *    -1 if an error occurred and m was freed
 */
static int
udp4_espinudp(struct mbuf **mp, int off)
{
        const size_t skip = sizeof(struct udphdr);
        size_t len;
        uint8_t *data;
        size_t minlen;
        size_t iphdrlen;
        struct ip *ip;
        struct m_tag *tag;
        struct udphdr *udphdr;
        u_int16_t sport, dport;
        struct mbuf *m = *mp;
        uint32_t *marker;

        minlen = off + sizeof(struct esp);
        if (minlen > m->m_pkthdr.len)
                minlen = m->m_pkthdr.len;

        if (m->m_len < minlen) {
                if ((*mp = m_pullup(m, minlen)) == NULL) {
                        return -1; /* dropped */
                }
                m = *mp;
        }

        len = m->m_len - off;
        data = mtod(m, uint8_t *) + off;

        /* Ignore keepalive packets. */
        if ((len == 1) && (*data == 0xff)) {
                m_freem(m);
                *mp = NULL; /* avoid any further processing by caller */
                return 1;       /* consumed */
        }

        /* Handle Non-ESP marker (32bit). If zero, then IKE. */
        marker = (uint32_t *)data;
        if (len <= sizeof(uint32_t))
                return 0;       /* passthrough */
        if (marker[0] == 0)
                return 0;       /* passthrough */

        /*
         * Get the UDP ports. They are handled in network order
         * everywhere in the IPSEC_NAT_T code.
         */
        udphdr = (struct udphdr *)((char *)data - skip);
        sport = udphdr->uh_sport;
        dport = udphdr->uh_dport;

        /*
         * Remove the UDP header, plus a possible marker. IP header
         * length is iphdrlen.
         *
         * Before:
         *   <--- off --->
         *   +----+------+-----+
         *   | IP |  UDP | ESP |
         *   +----+------+-----+
         *        <-skip->
         * After:
         *          +----+-----+
         *          | IP | ESP |
         *          +----+-----+
         *   <-skip->
         */
        iphdrlen = off - sizeof(struct udphdr);
        memmove(mtod(m, char *) + skip, mtod(m, void *), iphdrlen);
        m_adj(m, skip);

        ip = mtod(m, struct ip *);
        ip->ip_len = htons(ntohs(ip->ip_len) - skip);
        ip->ip_p = IPPROTO_ESP;

        /*
         * We have modified the packet - it is now ESP, so we should not
         * return to UDP processing.
         *
         * Add a PACKET_TAG_IPSEC_NAT_T_PORTS tag to remember the source
         * UDP port. This is required if we want to select the right SPD
         * for multiple hosts behind same NAT.
         */
        if ((tag = m_tag_get(PACKET_TAG_IPSEC_NAT_T_PORTS,
            sizeof(sport) + sizeof(dport), M_DONTWAIT)) == NULL) {
                m_freem(m);
                *mp = NULL;
                return -1;      /* dropped */
        }
        ((u_int16_t *)(tag + 1))[0] = sport;
        ((u_int16_t *)(tag + 1))[1] = dport;
        m_tag_prepend(m, tag);

        if (ipsec_used)
                ipsec4_common_input(m, iphdrlen, IPPROTO_ESP);
        else
                m_freem(m);

        /* We handled it, it shouldn't be handled by UDP */
        *mp = NULL; /* avoid free by caller ... */
        return 1;               /* consumed */
}
#endif

PR_WRAP_USRREQS(udp)
#define udp_attach      udp_attach_wrapper
#define udp_detach      udp_detach_wrapper
#define udp_accept      udp_accept_wrapper
#define udp_bind        udp_bind_wrapper
#define udp_listen      udp_listen_wrapper
#define udp_connect     udp_connect_wrapper
#define udp_connect2    udp_connect2_wrapper
#define udp_disconnect  udp_disconnect_wrapper
#define udp_shutdown    udp_shutdown_wrapper
#define udp_abort       udp_abort_wrapper
#define udp_ioctl       udp_ioctl_wrapper
#define udp_stat        udp_stat_wrapper
#define udp_peeraddr    udp_peeraddr_wrapper
#define udp_sockaddr    udp_sockaddr_wrapper
#define udp_rcvd        udp_rcvd_wrapper
#define udp_recvoob     udp_recvoob_wrapper
#define udp_send        udp_send_wrapper
#define udp_sendoob     udp_sendoob_wrapper
#define udp_purgeif     udp_purgeif_wrapper

const struct pr_usrreqs udp_usrreqs = {
        .pr_attach      = udp_attach,
        .pr_detach      = udp_detach,
        .pr_accept      = udp_accept,
        .pr_bind        = udp_bind,
        .pr_listen      = udp_listen,
        .pr_connect     = udp_connect,
        .pr_connect2    = udp_connect2,
        .pr_disconnect  = udp_disconnect,
        .pr_shutdown    = udp_shutdown,
        .pr_abort       = udp_abort,
        .pr_ioctl       = udp_ioctl,
        .pr_stat        = udp_stat,
        .pr_peeraddr    = udp_peeraddr,
        .pr_sockaddr    = udp_sockaddr,
        .pr_rcvd        = udp_rcvd,
        .pr_recvoob     = udp_recvoob,
        .pr_send        = udp_send,
        .pr_sendoob     = udp_sendoob,
        .pr_purgeif     = udp_purgeif,
};