/*      $OpenBSD: udp_usrreq.c,v 1.350 2025/10/24 15:09:56 bluhm Exp $  */
/*      $NetBSD: udp_usrreq.c,v 1.28 1996/03/16 23:54:03 christos Exp $ */

/*
 * Copyright (c) 1982, 1986, 1988, 1990, 1993
 *      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.
 *
 *      @(#)COPYRIGHT   1.1 (NRL) 17 January 1995
 *
 * NRL grants permission for redistribution and use in source and binary
 * forms, with or without modification, of the software and documentation
 * created at NRL 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgements:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 *      This product includes software developed at the Information
 *      Technology Division, US Naval Research Laboratory.
 * 4. Neither the name of the NRL nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THE SOFTWARE PROVIDED BY NRL IS PROVIDED BY NRL 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 NRL 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.
 *
 * The views and conclusions contained in the software and documentation
 * are those of the authors and should not be interpreted as representing
 * official policies, either expressed or implied, of the US Naval
 * Research Laboratory (NRL).
 */

#include "pf.h"
#include "stoeplitz.h"

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

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

#include <netinet/in.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>

#ifdef IPSEC
#include <netinet/ip_ipsp.h>
#include <netinet/ip_esp.h>
#endif

#ifdef INET6
#include <netinet6/in6_var.h>
#include <netinet6/ip6_var.h>
#include <netinet6/ip6protosw.h>
#endif /* INET6 */

#if NPF > 0
#include <net/pfvar.h>
#endif

#ifdef PIPEX
#include <net/pipex.h>
#endif

/*
 * Locks used to protect data:
 *      a       atomic
 */

/*
 * UDP protocol implementation.
 * Per RFC 768, August, 1980.
 */
int     udpcksum = 1;                   /* [a] */

u_int   udp_sendspace = 9216;           /* [a] really max datagram size */
u_int   udp_recvspace = 40 * (1024 + sizeof(struct sockaddr_in));
                                        /* [a] 40 1K datagrams */

const struct pr_usrreqs udp_usrreqs = {
        .pru_attach     = udp_attach,
        .pru_detach     = udp_detach,
        .pru_bind       = udp_bind,
        .pru_connect    = udp_connect,
        .pru_disconnect = udp_disconnect,
        .pru_shutdown   = udp_shutdown,
        .pru_send       = udp_send,
        .pru_control    = in_control,
        .pru_sockaddr   = in_sockaddr,
        .pru_peeraddr   = in_peeraddr,
        .pru_flowid     = in_flowid,
};

#ifdef INET6
const struct pr_usrreqs udp6_usrreqs = {
        .pru_attach     = udp_attach,
        .pru_detach     = udp_detach,
        .pru_bind       = udp_bind,
        .pru_connect    = udp_connect,
        .pru_disconnect = udp_disconnect,
        .pru_shutdown   = udp_shutdown,
        .pru_send       = udp_send,
        .pru_control    = in6_control,
        .pru_sockaddr   = in6_sockaddr,
        .pru_peeraddr   = in6_peeraddr,
        .pru_flowid     = in_flowid,
};
#endif

#ifndef SMALL_KERNEL
const struct sysctl_bounded_args udpctl_vars[] = {
        { UDPCTL_CHECKSUM, &udpcksum, 0, 1 },
        { UDPCTL_RECVSPACE, &udp_recvspace, 0, SB_MAX },
        { UDPCTL_SENDSPACE, &udp_sendspace, 0, SB_MAX },
};
#endif /* SMALL_KERNEL */

struct  inpcbtable udbtable;
#ifdef INET6
struct  inpcbtable udb6table;
#endif
struct  cpumem *udpcounters;

void    udp_sbappend(struct inpcb *, struct mbuf *, struct ip *,
            struct ip6_hdr *, int, struct udphdr *, struct sockaddr *,
            u_int32_t, struct netstack *);
int     udp_output(struct inpcb *, struct mbuf *, struct mbuf *, struct mbuf *);
void    udp_notify(struct inpcb *, int);
int     udp_sysctl_udpstat(void *, size_t *, void *);

#ifndef UDB_INITIAL_HASH_SIZE
#define UDB_INITIAL_HASH_SIZE   128
#endif

void
udp_init(void)
{
        udpcounters = counters_alloc(udps_ncounters);
        in_pcbinit(&udbtable, UDB_INITIAL_HASH_SIZE);
#ifdef INET6
        in_pcbinit(&udb6table, UDB_INITIAL_HASH_SIZE);
#endif
}

int
udp_input(struct mbuf **mp, int *offp, int proto, int af, struct netstack *ns)
{
        struct mbuf *m = *mp;
        int iphlen = *offp;
        struct ip *ip = NULL;
        struct udphdr *uh;
        struct inpcb *inp = NULL;
        struct ip save_ip;
        int len;
        u_int16_t savesum;
        union {
                struct sockaddr sa;
                struct sockaddr_in sin;
#ifdef INET6
                struct sockaddr_in6 sin6;
#endif /* INET6 */
        } srcsa, dstsa;
        struct ip6_hdr *ip6 = NULL;
        u_int32_t ipsecflowinfo = 0;
#ifdef IPSEC
        int udpencap_port_local = atomic_load_int(&udpencap_port);
#endif /* IPSEC */

        udpstat_inc(udps_ipackets);

        uh = ip6_exthdr_get(mp, iphlen, sizeof(struct udphdr));
        if (uh == NULL) {
                udpstat_inc(udps_hdrops);
                return IPPROTO_DONE;
        }

        /* Check for illegal destination port 0 */
        if (uh->uh_dport == 0) {
                udpstat_inc(udps_noport);
                goto bad;
        }

        /*
         * Make mbuf data length reflect UDP length.
         * If not enough data to reflect UDP length, drop.
         */
        len = ntohs((u_int16_t)uh->uh_ulen);
        switch (af) {
        case AF_INET:
                if (m->m_pkthdr.len - iphlen != len) {
                        if (len > (m->m_pkthdr.len - iphlen) ||
                            len < sizeof(struct udphdr)) {
                                udpstat_inc(udps_badlen);
                                goto bad;
                        }
                        m_adj(m, len - (m->m_pkthdr.len - iphlen));
                }
                ip = mtod(m, struct ip *);
                /*
                 * Save a copy of the IP header in case we want restore it
                 * for sending an ICMP error message in response.
                 */
                save_ip = *ip;
                break;
#ifdef INET6
        case AF_INET6:
                /* jumbograms */
                if (len == 0 && m->m_pkthdr.len - iphlen > 0xffff)
                        len = m->m_pkthdr.len - iphlen;
                if (len != m->m_pkthdr.len - iphlen) {
                        udpstat_inc(udps_badlen);
                        goto bad;
                }
                ip6 = mtod(m, struct ip6_hdr *);
                break;
#endif /* INET6 */
        default:
                unhandled_af(af);
        }

        /*
         * Checksum extended UDP header and data.
         * from W.R.Stevens: check incoming udp cksums even if
         *      udpcksum is not set.
         */
        savesum = uh->uh_sum;
        if (uh->uh_sum == 0) {
                udpstat_inc(udps_nosum);
#ifdef INET6
                /*
                 * In IPv6, the UDP checksum is ALWAYS used.
                 */
                if (ip6)
                        goto bad;
#endif /* INET6 */
        } else {
                if ((m->m_pkthdr.csum_flags & M_UDP_CSUM_IN_OK) == 0) {
                        if (m->m_pkthdr.csum_flags & M_UDP_CSUM_IN_BAD) {
                                udpstat_inc(udps_badsum);
                                goto bad;
                        }
                        udpstat_inc(udps_inswcsum);

                        if (ip)
                                uh->uh_sum = in4_cksum(m, IPPROTO_UDP,
                                    iphlen, len);
#ifdef INET6
                        else if (ip6)
                                uh->uh_sum = in6_cksum(m, IPPROTO_UDP,
                                    iphlen, len);
#endif /* INET6 */
                        if (uh->uh_sum != 0) {
                                udpstat_inc(udps_badsum);
                                goto bad;
                        }
                }
        }
        CLR(m->m_pkthdr.csum_flags, M_UDP_CSUM_OUT);

#ifdef IPSEC
        if (atomic_load_int(&udpencap_enable) && udpencap_port_local &&
            atomic_load_int(&esp_enable) &&
#if NPF > 0
            !(m->m_pkthdr.pf.flags & PF_TAG_DIVERTED) &&
#endif
            uh->uh_dport == htons(udpencap_port_local)) {
                u_int32_t spi;
                int skip = iphlen + sizeof(struct udphdr);

                if (m->m_pkthdr.len - skip < sizeof(u_int32_t)) {
                        /* packet too short */
                        m_freem(m);
                        return IPPROTO_DONE;
                }
                m_copydata(m, skip, sizeof(u_int32_t), (caddr_t) &spi);
                /*
                 * decapsulate if the SPI is not zero, otherwise pass
                 * to userland
                 */
                if (spi != 0) {
                        int protoff;

                        if ((m = *mp = m_pullup(m, skip)) == NULL) {
                                udpstat_inc(udps_hdrops);
                                return IPPROTO_DONE;
                        }

                        /* remove the UDP header */
                        bcopy(mtod(m, u_char *),
                            mtod(m, u_char *) + sizeof(struct udphdr), iphlen);
                        m_adj(m, sizeof(struct udphdr));
                        skip -= sizeof(struct udphdr);

                        espstat_inc(esps_udpencin);
                        protoff = af == AF_INET ? offsetof(struct ip, ip_p) :
                            offsetof(struct ip6_hdr, ip6_nxt);
                        return ipsec_common_input(mp, skip, protoff,
                            af, IPPROTO_ESP, 1, ns);
                }
        }
#endif /* IPSEC */

        switch (af) {
        case AF_INET:
                bzero(&srcsa, sizeof(struct sockaddr_in));
                srcsa.sin.sin_len = sizeof(struct sockaddr_in);
                srcsa.sin.sin_family = AF_INET;
                srcsa.sin.sin_port = uh->uh_sport;
                srcsa.sin.sin_addr = ip->ip_src;

                bzero(&dstsa, sizeof(struct sockaddr_in));
                dstsa.sin.sin_len = sizeof(struct sockaddr_in);
                dstsa.sin.sin_family = AF_INET;
                dstsa.sin.sin_port = uh->uh_dport;
                dstsa.sin.sin_addr = ip->ip_dst;
                break;
#ifdef INET6
        case AF_INET6:
                bzero(&srcsa, sizeof(struct sockaddr_in6));
                srcsa.sin6.sin6_len = sizeof(struct sockaddr_in6);
                srcsa.sin6.sin6_family = AF_INET6;
                srcsa.sin6.sin6_port = uh->uh_sport;
#if 0 /*XXX inbound flowinfo */
                srcsa.sin6.sin6_flowinfo = htonl(0x0fffffff) & ip6->ip6_flow;
#endif
                /* KAME hack: recover scopeid */
                in6_recoverscope(&srcsa.sin6, &ip6->ip6_src);

                bzero(&dstsa, sizeof(struct sockaddr_in6));
                dstsa.sin6.sin6_len = sizeof(struct sockaddr_in6);
                dstsa.sin6.sin6_family = AF_INET6;
                dstsa.sin6.sin6_port = uh->uh_dport;
#if 0 /*XXX inbound flowinfo */
                dstsa.sin6.sin6_flowinfo = htonl(0x0fffffff) & ip6->ip6_flow;
#endif
                /* KAME hack: recover scopeid */
                in6_recoverscope(&dstsa.sin6, &ip6->ip6_dst);
                break;
#endif /* INET6 */
        }

        if (m->m_flags & (M_BCAST|M_MCAST)) {
                struct inpcbtable *table;
                struct inpcb_iterator iter = { .inp_table = NULL };
                struct inpcb *last;

                /*
                 * 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?)
                 */

#ifdef INET6
                if (ip6)
                        table = &udb6table;
                else
#endif
                        table = &udbtable;

                mtx_enter(&table->inpt_mtx);
                last = inp = NULL;
                while ((inp = in_pcb_iterator(table, inp, &iter)) != NULL) {
                        if (ip6)
                                KASSERT(ISSET(inp->inp_flags, INP_IPV6));
                        else
                                KASSERT(!ISSET(inp->inp_flags, INP_IPV6));

                        if (inp->inp_socket->so_rcv.sb_state & SS_CANTRCVMORE)
                                continue;
                        if (rtable_l2(inp->inp_rtableid) !=
                            rtable_l2(m->m_pkthdr.ph_rtableid))
                                continue;
                        if (inp->inp_lport != uh->uh_dport)
                                continue;
#ifdef INET6
                        if (ip6) {
                                if (inp->inp_ip6_minhlim &&
                                    inp->inp_ip6_minhlim > ip6->ip6_hlim)
                                        continue;
                                if (!IN6_IS_ADDR_UNSPECIFIED(&inp->inp_laddr6))
                                        if (!IN6_ARE_ADDR_EQUAL(
                                            &inp->inp_laddr6, &ip6->ip6_dst))
                                                continue;
                        } else
#endif /* INET6 */
                        {
                                if (inp->inp_ip_minttl &&
                                    inp->inp_ip_minttl > ip->ip_ttl)
                                        continue;

                                if (inp->inp_laddr.s_addr != INADDR_ANY) {
                                        if (inp->inp_laddr.s_addr !=
                                            ip->ip_dst.s_addr)
                                                continue;
                                }
                        }
#ifdef INET6
                        if (ip6) {
                                if (!IN6_IS_ADDR_UNSPECIFIED(&inp->inp_faddr6))
                                        if (!IN6_ARE_ADDR_EQUAL(
                                            &inp->inp_faddr6, &ip6->ip6_src) ||
                                            inp->inp_fport != uh->uh_sport)
                                                continue;
                        } else
#endif /* INET6 */
                        if (inp->inp_faddr.s_addr != INADDR_ANY) {
                                if (inp->inp_faddr.s_addr !=
                                    ip->ip_src.s_addr ||
                                    inp->inp_fport != uh->uh_sport)
                                        continue;
                        }

                        if (last != NULL) {
                                struct mbuf *n;

                                mtx_leave(&table->inpt_mtx);

                                n = m_copym(m, 0, M_COPYALL, M_NOWAIT);
                                if (n != NULL) {
                                        udp_sbappend(last, n, ip, ip6, iphlen,
                                            uh, &srcsa.sa, 0, ns);
                                }
                                in_pcbunref(last);

                                mtx_enter(&table->inpt_mtx);
                        }
                        last = in_pcbref(inp);

                        /*
                         * 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) {
                                in_pcb_iterator_abort(table, inp, &iter);
                                break;
                        }
                }
                mtx_leave(&table->inpt_mtx);

                if (last == NULL) {
                        /*
                         * No matching pcb found; discard datagram.
                         * (No need to send an ICMP Port Unreachable
                         * for a broadcast or multicast datagram.)
                         */
                        udpstat_inc(udps_noportbcast);
                        m_freem(m);
                        return IPPROTO_DONE;
                }

                udp_sbappend(last, m, ip, ip6, iphlen, uh, &srcsa.sa, 0, ns);
                in_pcbunref(last);

                return IPPROTO_DONE;
        }
        /*
         * Locate pcb for datagram.
         */
#if NPF > 0
        inp = pf_inp_lookup(m);
#endif
        if (inp == NULL) {
#ifdef INET6
                if (ip6) {
                        inp = in6_pcblookup(&udb6table, &ip6->ip6_src,
                            uh->uh_sport, &ip6->ip6_dst, uh->uh_dport,
                            m->m_pkthdr.ph_rtableid);
                } else
#endif /* INET6 */
                {
                        inp = in_pcblookup(&udbtable, ip->ip_src,
                            uh->uh_sport, ip->ip_dst, uh->uh_dport,
                            m->m_pkthdr.ph_rtableid);
                }
        }
        if (inp == NULL) {
                udpstat_inc(udps_pcbhashmiss);
#ifdef INET6
                if (ip6) {
                        inp = in6_pcblookup_listen(&udb6table, &ip6->ip6_dst,
                            uh->uh_dport, m, m->m_pkthdr.ph_rtableid);
                } else
#endif /* INET6 */
                {
                        inp = in_pcblookup_listen(&udbtable, ip->ip_dst,
                            uh->uh_dport, m, m->m_pkthdr.ph_rtableid);
                }
        }

#ifdef IPSEC
        if (ipsec_in_use) {
                struct m_tag *mtag;
                struct tdb_ident *tdbi;
                struct tdb *tdb;
                int error;

                mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
                if (mtag != NULL) {
                        tdbi = (struct tdb_ident *)(mtag + 1);
                        tdb = gettdb(tdbi->rdomain, tdbi->spi,
                            &tdbi->dst, tdbi->proto);
                } else
                        tdb = NULL;
                error = ipsp_spd_lookup(m, af, iphlen, IPSP_DIRECTION_IN,
                    tdb, inp ? &inp->inp_seclevel : NULL, NULL, NULL);
                if (error) {
                        udpstat_inc(udps_nosec);
                        tdb_unref(tdb);
                        goto bad;
                }
                /* create ipsec options, id is not modified after creation */
                if (tdb && tdb->tdb_ids)
                        ipsecflowinfo = tdb->tdb_ids->id_flow;
                tdb_unref(tdb);
        }
#endif /*IPSEC */

        if (inp == NULL) {
                udpstat_inc(udps_noport);
                if (m->m_flags & (M_BCAST | M_MCAST)) {
                        udpstat_inc(udps_noportbcast);
                        goto bad;
                }
#ifdef INET6
                if (ip6) {
                        uh->uh_sum = savesum;
                        icmp6_error(m, ICMP6_DST_UNREACH,
                            ICMP6_DST_UNREACH_NOPORT,0);
                } else
#endif /* INET6 */
                {
                        *ip = save_ip;
                        uh->uh_sum = savesum;
                        icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_PORT,
                            0, 0);
                }
                return IPPROTO_DONE;
        }

        soassertlocked_readonly(inp->inp_socket);

#ifdef INET6
        if (ip6 && inp->inp_ip6_minhlim &&
            inp->inp_ip6_minhlim > ip6->ip6_hlim) {
                goto bad;
        } else
#endif
        if (ip && inp->inp_ip_minttl &&
            inp->inp_ip_minttl > ip->ip_ttl) {
                goto bad;
        }

#if NPF > 0
        if (inp->inp_socket->so_state & SS_ISCONNECTED)
                pf_inp_link(m, inp);
#endif

#ifdef PIPEX
        if (pipex_enable && inp->inp_pipex) {
                struct pipex_session *session;
                int off = iphlen + sizeof(struct udphdr);

                if ((session = pipex_l2tp_lookup_session(m, off, &srcsa.sa))
                    != NULL) {
                        m = *mp = pipex_l2tp_input(m, off, session,
                            ipsecflowinfo, ns);
                        pipex_rele_session(session);
                        if (m == NULL) {
                                in_pcbunref(inp);
                                return IPPROTO_DONE;
                        }
                }
        }
#endif

        udp_sbappend(inp, m, ip, ip6, iphlen, uh, &srcsa.sa, ipsecflowinfo, ns);
        in_pcbunref(inp);
        return IPPROTO_DONE;
bad:
        m_freem(m);
        in_pcbunref(inp);
        return IPPROTO_DONE;
}

void
udp_sbappend(struct inpcb *inp, struct mbuf *m, struct ip *ip,
    struct ip6_hdr *ip6, int hlen, struct udphdr *uh,
    struct sockaddr *srcaddr, u_int32_t ipsecflowinfo,
    struct netstack *ns)
{
        struct socket *so = inp->inp_socket;
        struct mbuf *opts = NULL;

        hlen += sizeof(*uh);

        if (inp->inp_upcall != NULL) {
                m = (*inp->inp_upcall)(inp->inp_upcall_arg, m,
                    ip, ip6, uh, hlen, ns);
                if (m == NULL)
                        return;
        }

#ifdef INET6
        if (ip6 && (inp->inp_flags & IN6P_CONTROLOPTS ||
            so->so_options & SO_TIMESTAMP))
                ip6_savecontrol(inp, m, &opts);
#endif /* INET6 */
        if (ip && (inp->inp_flags & INP_CONTROLOPTS ||
            so->so_options & SO_TIMESTAMP))
                ip_savecontrol(inp, &opts, ip, m);
#ifdef INET6
        if (ip6 && (inp->inp_flags & IN6P_RECVDSTPORT)) {
                struct mbuf **mp = &opts;

                while (*mp)
                        mp = &(*mp)->m_next;
                *mp = sbcreatecontrol((caddr_t)&uh->uh_dport, sizeof(u_int16_t),
                    IPV6_RECVDSTPORT, IPPROTO_IPV6);
        }
#endif /* INET6 */
        if (ip && (inp->inp_flags & INP_RECVDSTPORT)) {
                struct mbuf **mp = &opts;

                while (*mp)
                        mp = &(*mp)->m_next;
                *mp = sbcreatecontrol((caddr_t)&uh->uh_dport, sizeof(u_int16_t),
                    IP_RECVDSTPORT, IPPROTO_IP);
        }
#ifdef IPSEC
        if (ipsecflowinfo && (inp->inp_flags & INP_IPSECFLOWINFO)) {
                struct mbuf **mp = &opts;

                while (*mp)
                        mp = &(*mp)->m_next;
                *mp = sbcreatecontrol((caddr_t)&ipsecflowinfo,
                    sizeof(u_int32_t), IP_IPSECFLOWINFO, IPPROTO_IP);
        }
#endif
        m_adj(m, hlen);

        mtx_enter(&so->so_rcv.sb_mtx);
        if (sbappendaddr(&so->so_rcv, srcaddr, m, opts) == 0) {
                mtx_leave(&so->so_rcv.sb_mtx);
                udpstat_inc(udps_fullsock);
                m_freem(m);
                m_freem(opts);
                return;
        }
        mtx_leave(&so->so_rcv.sb_mtx);

        sorwakeup(so);
}

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

#ifdef INET6
void
udp6_ctlinput(int cmd, struct sockaddr *sa, u_int rdomain, void *d)
{
        struct udphdr uh;
        struct sockaddr_in6 sa6;
        struct ip6_hdr *ip6;
        struct mbuf *m;
        int off;
        void *cmdarg;
        struct ip6ctlparam *ip6cp = NULL;
        struct udp_portonly {
                u_int16_t uh_sport;
                u_int16_t uh_dport;
        } *uhp;
        struct inpcb *inp;
        void (*notify)(struct inpcb *, int) = udp_notify;

        if (sa == NULL)
                return;
        if (sa->sa_family != AF_INET6 ||
            sa->sa_len != sizeof(struct sockaddr_in6))
                return;

        if ((unsigned)cmd >= PRC_NCMDS)
                return;
        if (PRC_IS_REDIRECT(cmd))
                notify = in_pcbrtchange, d = NULL;
        else if (cmd == PRC_HOSTDEAD)
                d = NULL;
        else if (cmd == PRC_MSGSIZE)
                ; /* special code is present, see below */
        else if (inet6ctlerrmap[cmd] == 0)
                return;

        /* if the parameter is from icmp6, decode it. */
        if (d != NULL) {
                ip6cp = (struct ip6ctlparam *)d;
                m = ip6cp->ip6c_m;
                ip6 = ip6cp->ip6c_ip6;
                off = ip6cp->ip6c_off;
                cmdarg = ip6cp->ip6c_cmdarg;
        } else {
                m = NULL;
                ip6 = NULL;
                cmdarg = NULL;
                /* XXX: translate addresses into internal form */
                sa6 = *satosin6(sa);
                if (in6_embedscope(&sa6.sin6_addr, &sa6, NULL, NULL)) {
                        /* should be impossible */
                        return;
                }
        }

        if (ip6cp && ip6cp->ip6c_finaldst) {
                bzero(&sa6, sizeof(sa6));
                sa6.sin6_family = AF_INET6;
                sa6.sin6_len = sizeof(sa6);
                sa6.sin6_addr = *ip6cp->ip6c_finaldst;
                /* XXX: assuming M is valid in this case */
                sa6.sin6_scope_id = in6_addr2scopeid(m->m_pkthdr.ph_ifidx,
                    ip6cp->ip6c_finaldst);
                if (in6_embedscope(ip6cp->ip6c_finaldst, &sa6, NULL, NULL)) {
                        /* should be impossible */
                        return;
                }
        } else {
                /* XXX: translate addresses into internal form */
                sa6 = *satosin6(sa);
                if (in6_embedscope(&sa6.sin6_addr, &sa6, NULL, NULL)) {
                        /* should be impossible */
                        return;
                }
        }

        if (ip6) {
                /*
                 * XXX: We assume that when IPV6 is non NULL,
                 * M and OFF are valid.
                 */
                struct sockaddr_in6 sa6_src;

                /* check if we can safely examine src and dst ports */
                if (m->m_pkthdr.len < off + sizeof(*uhp))
                        return;

                bzero(&uh, sizeof(uh));
                m_copydata(m, off, sizeof(*uhp), (caddr_t)&uh);

                bzero(&sa6_src, sizeof(sa6_src));
                sa6_src.sin6_family = AF_INET6;
                sa6_src.sin6_len = sizeof(sa6_src);
                sa6_src.sin6_addr = ip6->ip6_src;
                sa6_src.sin6_scope_id = in6_addr2scopeid(m->m_pkthdr.ph_ifidx,
                    &ip6->ip6_src);
                if (in6_embedscope(&sa6_src.sin6_addr, &sa6_src, NULL, NULL)) {
                        /* should be impossible */
                        return;
                }

                if (cmd == PRC_MSGSIZE) {
                        /*
                         * Check to see if we have a valid UDP socket
                         * corresponding to the address in the ICMPv6 message
                         * payload.
                         */
                        inp = in6_pcblookup(&udb6table, &sa6.sin6_addr,
                            uh.uh_dport, &sa6_src.sin6_addr, uh.uh_sport,
                            rdomain);
#if 0
                        /*
                         * As the use of sendto(2) is fairly popular,
                         * we may want to allow non-connected pcb too.
                         * But it could be too weak against attacks...
                         * We should at least check if the local address (= s)
                         * is really ours.
                         */
                        if (inp == NULL) {
                                inp = in6_pcblookup_listen(&udb6table,
                                    &sa6_src.sin6_addr, uh.uh_sport, NULL,
                                    rdomain))
                        }
#endif

                        /*
                         * Depending on the value of "valid" and routing table
                         * size (mtudisc_{hi,lo}wat), we will:
                         * - recalculate the new MTU and create the
                         *   corresponding routing entry, or
                         * - ignore the MTU change notification.
                         */
                        icmp6_mtudisc_update((struct ip6ctlparam *)d,
                            inp != NULL);
                        in_pcbunref(inp);

                        /*
                         * regardless of if we called icmp6_mtudisc_update(),
                         * we need to call in6_pcbnotify(), to notify path
                         * MTU change to the userland (2292bis-02), because
                         * some unconnected sockets may share the same
                         * destination and want to know the path MTU.
                         */
                }

                in6_pcbnotify(&udb6table, &sa6, uh.uh_dport,
                    &sa6_src, uh.uh_sport, rdomain, cmd, cmdarg, notify);
        } else {
                in6_pcbnotify(&udb6table, &sa6, 0,
                    &sa6_any, 0, rdomain, cmd, cmdarg, notify);
        }
}
#endif

void
udp_ctlinput(int cmd, struct sockaddr *sa, u_int rdomain, void *v)
{
        struct ip *ip = v;
        struct udphdr *uhp;
        struct in_addr faddr;
        void (*notify)(struct inpcb *, int) = udp_notify;
        int errno;

        if (sa == NULL)
                return;
        if (sa->sa_family != AF_INET ||
            sa->sa_len != sizeof(struct sockaddr_in))
                return;
        faddr = satosin(sa)->sin_addr;
        if (faddr.s_addr == INADDR_ANY)
                return;

        if ((unsigned)cmd >= PRC_NCMDS)
                return;
        errno = inetctlerrmap[cmd];
        if (PRC_IS_REDIRECT(cmd))
                notify = in_pcbrtchange, ip = NULL;
        else if (cmd == PRC_HOSTDEAD)
                ip = NULL;
        else if (errno == 0)
                return;

        if (ip) {
                struct inpcb *inp;
                struct socket *so = NULL;
#ifdef IPSEC
                int udpencap_port_local = atomic_load_int(&udpencap_port);
#endif

                uhp = (struct udphdr *)((caddr_t)ip + (ip->ip_hl << 2));
#ifdef IPSEC
                /* PMTU discovery for udpencap */
                if (cmd == PRC_MSGSIZE && atomic_load_int(&ip_mtudisc) &&
                    atomic_load_int(&udpencap_enable) && udpencap_port_local &&
                    uhp->uh_sport == udpencap_port_local) {
                        udpencap_ctlinput(cmd, sa, rdomain, v);
                        return;
                }
#endif
                inp = in_pcblookup(&udbtable,
                    ip->ip_dst, uhp->uh_dport, ip->ip_src, uhp->uh_sport,
                    rdomain);
                if (inp != NULL)
                        so = in_pcbsolock(inp);
                if (so != NULL)
                        notify(inp, errno);
                in_pcbsounlock(inp, so);
                in_pcbunref(inp);
        } else
                in_pcbnotifyall(&udbtable, satosin(sa), rdomain, errno, notify);
}

int
udp_output(struct inpcb *inp, struct mbuf *m, struct mbuf *addr,
    struct mbuf *control)
{
        struct sockaddr_in *sin = NULL;
        struct udpiphdr *ui;
        u_int32_t ipsecflowinfo = 0;
        struct sockaddr_in src_sin;
        int len = m->m_pkthdr.len;
        struct in_addr laddr;
        int error = 0;

#ifdef INET6
        if (ISSET(inp->inp_flags, INP_IPV6))
                return (udp6_output(inp, m, addr, control));
#endif

        /*
         * 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;
        }

        memset(&src_sin, 0, sizeof(src_sin));

        if (control) {
                u_int clen;
                struct cmsghdr *cm;
                caddr_t cmsgs;

                /*
                 * XXX: Currently, we assume all the optional information is
                 * stored in a single mbuf.
                 */
                if (control->m_next) {
                        error = EINVAL;
                        goto release;
                }

                clen = control->m_len;
                cmsgs = mtod(control, caddr_t);
                do {
                        if (clen < CMSG_LEN(0)) {
                                error = EINVAL;
                                goto release;
                        }
                        cm = (struct cmsghdr *)cmsgs;
                        if (cm->cmsg_len < CMSG_LEN(0) ||
                            CMSG_ALIGN(cm->cmsg_len) > clen) {
                                error = EINVAL;
                                goto release;
                        }
#ifdef IPSEC
                        if ((inp->inp_flags & INP_IPSECFLOWINFO) != 0 &&
                            cm->cmsg_len == CMSG_LEN(sizeof(ipsecflowinfo)) &&
                            cm->cmsg_level == IPPROTO_IP &&
                            cm->cmsg_type == IP_IPSECFLOWINFO) {
                                ipsecflowinfo = *(u_int32_t *)CMSG_DATA(cm);
                        } else
#endif
                        if (cm->cmsg_len == CMSG_LEN(sizeof(struct in_addr)) &&
                            cm->cmsg_level == IPPROTO_IP &&
                            cm->cmsg_type == IP_SENDSRCADDR) {
                                memcpy(&src_sin.sin_addr, CMSG_DATA(cm),
                                    sizeof(struct in_addr));
                                src_sin.sin_family = AF_INET;
                                src_sin.sin_len = sizeof(src_sin);
                                /* no check on reuse when sin->sin_port == 0 */
                                if ((error = in_pcbaddrisavail(inp, &src_sin,
                                    0, curproc)))
                                        goto release;
                        }
                        clen -= CMSG_ALIGN(cm->cmsg_len);
                        cmsgs += CMSG_ALIGN(cm->cmsg_len);
                } while (clen);
        }

        if (addr) {
                if ((error = in_nam2sin(addr, &sin)))
                        goto release;
                if (sin->sin_port == 0) {
                        error = EADDRNOTAVAIL;
                        goto release;
                }
                if (inp->inp_faddr.s_addr != INADDR_ANY) {
                        error = EISCONN;
                        goto release;
                }
                error = in_pcbselsrc(&laddr, sin, inp);
                if (error)
                        goto release;

                if (inp->inp_lport == 0) {
                        error = in_pcbbind(inp, NULL, curproc);
                        if (error)
                                goto release;
                }

                if (src_sin.sin_len > 0 &&
                    src_sin.sin_addr.s_addr != INADDR_ANY &&
                    src_sin.sin_addr.s_addr != inp->inp_laddr.s_addr) {
                        src_sin.sin_port = inp->inp_lport;
                        if (inp->inp_laddr.s_addr != INADDR_ANY &&
                            (error =
                            in_pcbaddrisavail(inp, &src_sin, 0, curproc)))
                                goto release;
                        laddr = src_sin.sin_addr;
                }
        } else {
                if (inp->inp_faddr.s_addr == INADDR_ANY) {
                        error = ENOTCONN;
                        goto release;
                }
                laddr = inp->inp_laddr;
        }

        /*
         * 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 bail;
        }

        /*
         * Fill in mbuf with extended UDP header
         * and addresses and length put into network format.
         */
        ui = mtod(m, struct udpiphdr *);
        bzero(ui->ui_x1, sizeof ui->ui_x1);
        ui->ui_pr = IPPROTO_UDP;
        ui->ui_len = htons((u_int16_t)len + sizeof (struct udphdr));
        ui->ui_src = laddr;
        ui->ui_dst = sin ? sin->sin_addr : inp->inp_faddr;
        ui->ui_sport = inp->inp_lport;
        ui->ui_dport = sin ? sin->sin_port : inp->inp_fport;
        ui->ui_ulen = ui->ui_len;
        ((struct ip *)ui)->ip_len = htons(sizeof (struct udpiphdr) + len);
        ((struct ip *)ui)->ip_ttl = inp->inp_ip.ip_ttl;
        ((struct ip *)ui)->ip_tos = inp->inp_ip.ip_tos;
        if (atomic_load_int(&udpcksum))
                m->m_pkthdr.csum_flags |= M_UDP_CSUM_OUT;

        udpstat_inc(udps_opackets);

        /* force routing table */
        m->m_pkthdr.ph_rtableid = inp->inp_rtableid;

        if (inp->inp_socket->so_state & SS_ISCONNECTED) {
#if NPF > 0
                pf_mbuf_link_inpcb(m, inp);
#endif
#if NSTOEPLITZ > 0
                m->m_pkthdr.ph_flowid = inp->inp_flowid;
                SET(m->m_pkthdr.csum_flags, M_FLOWID);
#endif
        }

        error = ip_output(m, inp->inp_options, &inp->inp_route,
            (inp->inp_socket->so_options & SO_BROADCAST), inp->inp_moptions,
            &inp->inp_seclevel, ipsecflowinfo);

bail:
        m_freem(control);
        return (error);

release:
        m_freem(m);
        goto bail;
}

int
udp_attach(struct socket *so, int proto, int wait)
{
        struct inpcbtable *table;
        int error;

        if (so->so_pcb != NULL)
                return EINVAL;

        if ((error = soreserve(so, atomic_load_int(&udp_sendspace),
            atomic_load_int(&udp_recvspace))))
                return error;

#ifdef INET6
        if (so->so_proto->pr_domain->dom_family == PF_INET6)
                table = &udb6table;
        else
#endif
                table = &udbtable;
        if ((error = in_pcballoc(so, table, wait)))
                return error;
#ifdef INET6
        if (ISSET(sotoinpcb(so)->inp_flags, INP_IPV6))
                sotoinpcb(so)->inp_ipv6.ip6_hlim =
                    atomic_load_int(&ip6_defhlim);
        else
#endif
                sotoinpcb(so)->inp_ip.ip_ttl = atomic_load_int(&ip_defttl);
        return 0;
}

int
udp_detach(struct socket *so)
{
        struct inpcb *inp;

        soassertlocked(so);

        inp = sotoinpcb(so);
        if (inp == NULL)
                return (EINVAL);

        in_pcbdetach(inp);
        return (0);
}

int
udp_bind(struct socket *so, struct mbuf *addr, struct proc *p)
{
        struct inpcb *inp = sotoinpcb(so);

        soassertlocked(so);
        return in_pcbbind(inp, addr, p);
}

int
udp_connect(struct socket *so, struct mbuf *addr)
{
        struct inpcb *inp = sotoinpcb(so);
        int error;

        soassertlocked(so);

#ifdef INET6
        if (ISSET(inp->inp_flags, INP_IPV6)) {
                if (!IN6_IS_ADDR_UNSPECIFIED(&inp->inp_faddr6))
                        return (EISCONN);
        } else
#endif
        {
                if (inp->inp_faddr.s_addr != INADDR_ANY)
                        return (EISCONN);
        }
        error = in_pcbconnect(inp, addr);
        if (error)
                return (error);

        soisconnected(so);
        return (0);
}

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

        soassertlocked(so);

#ifdef INET6
        if (ISSET(inp->inp_flags, INP_IPV6)) {
                if (IN6_IS_ADDR_UNSPECIFIED(&inp->inp_faddr6))
                        return (ENOTCONN);
        } else
#endif
        {
                if (inp->inp_faddr.s_addr == INADDR_ANY)
                        return (ENOTCONN);
        }
        in_pcbunset_laddr(inp);
        in_pcbdisconnect(inp);
        so->so_state &= ~SS_ISCONNECTED;                /* XXX */

        return (0);
}

int
udp_shutdown(struct socket *so)
{
        soassertlocked(so);
        socantsendmore(so);
        return (0);
}

int
udp_send(struct socket *so, struct mbuf *m, struct mbuf *addr,
    struct mbuf *control)
{
        struct inpcb *inp = sotoinpcb(so);

        soassertlocked_readonly(so);

        if (inp == NULL) {
                /* PCB could be destroyed, but socket still spliced. */
                return (EINVAL);
        }

#ifdef PIPEX
        if (inp->inp_pipex) {
                struct pipex_session *session;

                if (addr != NULL)
                        session =
                            pipex_l2tp_userland_lookup_session(m,
                                mtod(addr, struct sockaddr *));
                else
#ifdef INET6
                if (ISSET(inp->inp_flags, INP_IPV6))
                        session =
                            pipex_l2tp_userland_lookup_session_ipv6(
                                m, inp->inp_faddr6);
                else
#endif
                        session =
                            pipex_l2tp_userland_lookup_session_ipv4(
                                m, inp->inp_faddr);
                if (session != NULL) {
                        m = pipex_l2tp_userland_output(m, session);
                        pipex_rele_session(session);

                        if (m == NULL) {
                                m_freem(control);
                                return (ENOMEM);
                        }
                }
        }
#endif

        return (udp_output(inp, m, addr, control));
}

#ifndef SMALL_KERNEL
/*
 * Sysctl for udp variables.
 */
int
udp_sysctl(int *name, u_int namelen, void *oldp, size_t *oldlenp, void *newp,
    size_t newlen)
{
        /* All sysctl names at this level are terminal. */
        if (namelen != 1)
                return (ENOTDIR);

        switch (name[0]) {
        case UDPCTL_ROOTONLY:
                if (newp && (int)atomic_load_int(&securelevel) > 0)
                        return (EPERM);
                /* FALLTHROUGH */
        case UDPCTL_BADDYNAMIC: {
                struct baddynamicports *ports = (name[0] == UDPCTL_ROOTONLY ?
                    &rootonlyports : &baddynamicports);
                const size_t bufitems = DP_MAPSIZE;
                const size_t buflen = bufitems * sizeof(uint32_t);
                size_t i;
                uint32_t *buf;
                int error;

                buf = malloc(buflen, M_SYSCTL, M_WAITOK | M_ZERO);

                NET_LOCK_SHARED();
                for (i = 0; i < bufitems; ++i)
                        buf[i] = ports->udp[i];
                NET_UNLOCK_SHARED();

                error = sysctl_struct(oldp, oldlenp, newp, newlen,
                    buf, buflen);

                if (error == 0 && newp) {
                        NET_LOCK();
                        for (i = 0; i < bufitems; ++i)
                                ports->udp[i] = buf[i];
                        NET_UNLOCK();
                }

                free(buf, M_SYSCTL, buflen);

                return (error);
        }
        case UDPCTL_STATS:
                if (newp != NULL)
                        return (EPERM);

                return (udp_sysctl_udpstat(oldp, oldlenp, newp));

        default:
                return (sysctl_bounded_arr(udpctl_vars, nitems(udpctl_vars),
                    name, namelen, oldp, oldlenp, newp, newlen));
        }
        /* NOTREACHED */
}

int
udp_sysctl_udpstat(void *oldp, size_t *oldlenp, void *newp)
{
        uint64_t counters[udps_ncounters];
        struct udpstat udpstat;
        u_long *words = (u_long *)&udpstat;
        int i;

        CTASSERT(sizeof(udpstat) == (nitems(counters) * sizeof(u_long)));
        memset(&udpstat, 0, sizeof udpstat);
        counters_read(udpcounters, counters, nitems(counters), NULL);

        for (i = 0; i < nitems(counters); i++)
                words[i] = (u_long)counters[i];

        return (sysctl_rdstruct(oldp, oldlenp, newp,
            &udpstat, sizeof(udpstat)));
}
#endif /* SMALL_KERNEL */