xnu-7195.60.75.tar.gz

[apple/xnu.git] / bsd / netinet6 / udp6_usrreq.c

/*
 * Copyright (c) 2000-2020 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 *
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 *
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */

/*      $FreeBSD: src/sys/netinet6/udp6_usrreq.c,v 1.6.2.6 2001/07/29 19:32:40 ume Exp $        */
/*      $KAME: udp6_usrreq.c,v 1.27 2001/05/21 05:45:10 jinmei 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, 1989, 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. 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_var.h   8.1 (Berkeley) 6/10/93
 */
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/param.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/sysctl.h>
#include <sys/errno.h>
#include <sys/stat.h>
#include <sys/systm.h>
#include <sys/syslog.h>
#include <sys/proc.h>
#include <sys/kauth.h>

#include <net/if.h>
#include <net/route.h>
#include <net/if_types.h>
#include <net/ntstat.h>
#include <net/dlil.h>
#include <net/net_api_stats.h>

#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/in_pcb.h>
#include <netinet/in_var.h>
#include <netinet/ip_var.h>
#include <netinet/udp.h>
#include <netinet/udp_var.h>
#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>
#include <netinet6/in6_pcb.h>
#include <netinet/icmp6.h>
#include <netinet6/udp6_var.h>
#include <netinet6/ip6protosw.h>

#if IPSEC
#include <netinet6/ipsec.h>
#include <netinet6/ipsec6.h>
#include <netinet6/esp6.h>
#include <netkey/key.h>
extern int ipsec_bypass;
extern int esp_udp_encap_port;
#endif /* IPSEC */

#if NECP
#include <net/necp.h>
#endif /* NECP */

#if FLOW_DIVERT
#include <netinet/flow_divert.h>
#endif /* FLOW_DIVERT */

#if CONTENT_FILTER
#include <net/content_filter.h>
#endif /* CONTENT_FILTER */

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

static int udp6_abort(struct socket *);
static int udp6_attach(struct socket *, int, struct proc *);
static int udp6_bind(struct socket *, struct sockaddr *, struct proc *);
static int udp6_connectx(struct socket *, struct sockaddr *,
    struct sockaddr *, struct proc *, uint32_t, sae_associd_t,
    sae_connid_t *, uint32_t, void *, uint32_t, struct uio *, user_ssize_t *);
static  int udp6_detach(struct socket *);
static int udp6_disconnect(struct socket *);
static int udp6_disconnectx(struct socket *, sae_associd_t, sae_connid_t);
static int udp6_send(struct socket *, int, struct mbuf *, struct sockaddr *,
    struct mbuf *, struct proc *);
static void udp6_append(struct inpcb *, struct ip6_hdr *,
    struct sockaddr_in6 *, struct mbuf *, int, struct ifnet *);
static int udp6_input_checksum(struct mbuf *, struct udphdr *, int, int);

struct pr_usrreqs udp6_usrreqs = {
        .pru_abort =            udp6_abort,
        .pru_attach =           udp6_attach,
        .pru_bind =             udp6_bind,
        .pru_connect =          udp6_connect,
        .pru_connectx =         udp6_connectx,
        .pru_control =          in6_control,
        .pru_detach =           udp6_detach,
        .pru_disconnect =       udp6_disconnect,
        .pru_disconnectx =      udp6_disconnectx,
        .pru_peeraddr =         in6_mapped_peeraddr,
        .pru_send =             udp6_send,
        .pru_shutdown =         udp_shutdown,
        .pru_sockaddr =         in6_mapped_sockaddr,
        .pru_sosend =           sosend,
        .pru_soreceive =        soreceive,
        .pru_soreceive_list =   soreceive_list,
};

/*
 * subroutine of udp6_input(), mainly for source code readability.
 */
static void
udp6_append(struct inpcb *last, struct ip6_hdr *ip6,
    struct sockaddr_in6 *udp_in6, struct mbuf *n, int off, struct ifnet *ifp)
{
#pragma unused(ip6)
        struct  mbuf *opts = NULL;
        int ret = 0;
        boolean_t cell = IFNET_IS_CELLULAR(ifp);
        boolean_t wifi = (!cell && IFNET_IS_WIFI(ifp));
        boolean_t wired = (!wifi && IFNET_IS_WIRED(ifp));

        if ((last->in6p_flags & INP_CONTROLOPTS) != 0 ||
#if CONTENT_FILTER
            /* Content Filter needs to see local address */
            (last->in6p_socket->so_cfil_db != NULL) ||
#endif
            (last->in6p_socket->so_options & SO_TIMESTAMP) != 0 ||
            (last->in6p_socket->so_options & SO_TIMESTAMP_MONOTONIC) != 0 ||
            (last->in6p_socket->so_options & SO_TIMESTAMP_CONTINUOUS) != 0) {
                ret = ip6_savecontrol(last, n, &opts);
                if (ret != 0) {
                        m_freem(n);
                        m_freem(opts);
                        return;
                }
        }
        m_adj(n, off);
        if (nstat_collect) {
                INP_ADD_STAT(last, cell, wifi, wired, rxpackets, 1);
                INP_ADD_STAT(last, cell, wifi, wired, rxbytes, n->m_pkthdr.len);
                inp_set_activity_bitmap(last);
        }
        so_recv_data_stat(last->in6p_socket, n, 0);
        if (sbappendaddr(&last->in6p_socket->so_rcv,
            (struct sockaddr *)udp_in6, n, opts, NULL) == 0) {
                udpstat.udps_fullsock++;
        } else {
                sorwakeup(last->in6p_socket);
        }
}

int
udp6_input(struct mbuf **mp, int *offp, int proto)
{
#pragma unused(proto)
        struct mbuf *m = *mp;
        struct ifnet *ifp;
        struct ip6_hdr *ip6;
        struct udphdr *uh;
        struct inpcb *in6p;
        struct  mbuf *opts = NULL;
        int off = *offp;
        int plen, ulen, ret = 0;
        boolean_t cell, wifi, wired;
        struct sockaddr_in6 udp_in6;
        struct inpcbinfo *pcbinfo = &udbinfo;
        struct sockaddr_in6 fromsa;
        u_int16_t pf_tag = 0;

        IP6_EXTHDR_CHECK(m, off, sizeof(struct udphdr), return IPPROTO_DONE);

        /* Expect 32-bit aligned data pointer on strict-align platforms */
        MBUF_STRICT_DATA_ALIGNMENT_CHECK_32(m);

        ifp = m->m_pkthdr.rcvif;
        ip6 = mtod(m, struct ip6_hdr *);
        cell = IFNET_IS_CELLULAR(ifp);
        wifi = (!cell && IFNET_IS_WIFI(ifp));
        wired = (!wifi && IFNET_IS_WIRED(ifp));

        if (m->m_flags & M_PKTHDR) {
                pf_tag = m_pftag(m)->pftag_tag;
        }

        udpstat.udps_ipackets++;

        plen = ntohs(ip6->ip6_plen) - off + sizeof(*ip6);
        uh = (struct udphdr *)(void *)((caddr_t)ip6 + off);
        ulen = ntohs((u_short)uh->uh_ulen);

        if (plen != ulen) {
                udpstat.udps_badlen++;
                IF_UDP_STATINC(ifp, badlength);
                goto bad;
        }

        /* destination port of 0 is illegal, based on RFC768. */
        if (uh->uh_dport == 0) {
                IF_UDP_STATINC(ifp, port0);
                goto bad;
        }

        /*
         * Checksum extended UDP header and data.
         */
        if (udp6_input_checksum(m, uh, off, ulen)) {
                goto bad;
        }

        /*
         * Construct sockaddr format source address.
         */
        init_sin6(&fromsa, m);
        fromsa.sin6_port = uh->uh_sport;

        if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
                int reuse_sock = 0, mcast_delivered = 0;
                struct ip6_moptions *imo;

                /*
                 * Deliver a multicast 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 multicasts 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?)
                 */

                /*
                 * In a case that laddr should be set to the link-local
                 * address (this happens in RIPng), the multicast address
                 * specified in the received packet does not match with
                 * laddr. To cure this situation, the matching is relaxed
                 * if the receiving interface is the same as one specified
                 * in the socket and if the destination multicast address
                 * matches one of the multicast groups specified in the socket.
                 */

                /*
                 * Construct sockaddr format source address.
                 */
                init_sin6(&udp_in6, m); /* general init */
                udp_in6.sin6_port = uh->uh_sport;
                /*
                 * KAME note: usually we drop udphdr from mbuf here.
                 * We need udphdr for IPsec processing so we do that later.
                 */

                /*
                 * Locate pcb(s) for datagram.
                 * (Algorithm copied from raw_intr().)
                 */
                lck_rw_lock_shared(pcbinfo->ipi_lock);

                LIST_FOREACH(in6p, &udb, inp_list) {
#if IPSEC
                        int skipit;
#endif /* IPSEC */

                        if ((in6p->inp_vflag & INP_IPV6) == 0) {
                                continue;
                        }

                        if (inp_restricted_recv(in6p, ifp)) {
                                continue;
                        }

                        if (in_pcb_checkstate(in6p, WNT_ACQUIRE, 0) ==
                            WNT_STOPUSING) {
                                continue;
                        }

                        udp_lock(in6p->in6p_socket, 1, 0);

                        if (in_pcb_checkstate(in6p, WNT_RELEASE, 1) ==
                            WNT_STOPUSING) {
                                udp_unlock(in6p->in6p_socket, 1, 0);
                                continue;
                        }
                        if (in6p->in6p_lport != uh->uh_dport) {
                                udp_unlock(in6p->in6p_socket, 1, 0);
                                continue;
                        }

                        /*
                         * Handle socket delivery policy for any-source
                         * and source-specific multicast. [RFC3678]
                         */
                        imo = in6p->in6p_moptions;
                        if (imo && IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
                                struct sockaddr_in6 mcaddr;
                                int blocked;

                                IM6O_LOCK(imo);
                                bzero(&mcaddr, sizeof(struct sockaddr_in6));
                                mcaddr.sin6_len = sizeof(struct sockaddr_in6);
                                mcaddr.sin6_family = AF_INET6;
                                mcaddr.sin6_addr = ip6->ip6_dst;

                                blocked = im6o_mc_filter(imo, ifp,
                                    &mcaddr, &fromsa);
                                IM6O_UNLOCK(imo);
                                if (blocked != MCAST_PASS) {
                                        udp_unlock(in6p->in6p_socket, 1, 0);
                                        if (blocked == MCAST_NOTSMEMBER ||
                                            blocked == MCAST_MUTED) {
                                                udpstat.udps_filtermcast++;
                                        }
                                        continue;
                                }
                        }
                        if (!IN6_IS_ADDR_UNSPECIFIED(&in6p->in6p_faddr) &&
                            (!IN6_ARE_ADDR_EQUAL(&in6p->in6p_faddr,
                            &ip6->ip6_src) ||
                            in6p->in6p_fport != uh->uh_sport)) {
                                udp_unlock(in6p->in6p_socket, 1, 0);
                                continue;
                        }

                        reuse_sock = in6p->inp_socket->so_options &
                            (SO_REUSEPORT | SO_REUSEADDR);

#if NECP
                        skipit = 0;
                        if (!necp_socket_is_allowed_to_send_recv_v6(in6p,
                            uh->uh_dport, uh->uh_sport, &ip6->ip6_dst,
                            &ip6->ip6_src, ifp, pf_tag, NULL, NULL, NULL, NULL)) {
                                /* do not inject data to pcb */
                                skipit = 1;
                        }
                        if (skipit == 0)
#endif /* NECP */
                        {
                                struct mbuf *n = NULL;
                                /*
                                 * KAME NOTE: do not
                                 * m_copy(m, offset, ...) below.
                                 * sbappendaddr() expects M_PKTHDR,
                                 * and m_copy() will copy M_PKTHDR
                                 * only if offset is 0.
                                 */
                                if (reuse_sock) {
                                        n = m_copy(m, 0, M_COPYALL);
                                }
                                udp6_append(in6p, ip6, &udp_in6, m,
                                    off + sizeof(struct udphdr), ifp);
                                mcast_delivered++;
                                m = n;
                        }
                        udp_unlock(in6p->in6p_socket, 1, 0);

                        /*
                         * 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 (reuse_sock == 0 || m == NULL) {
                                break;
                        }

                        /*
                         * Expect 32-bit aligned data pointer on strict-align
                         * platforms.
                         */
                        MBUF_STRICT_DATA_ALIGNMENT_CHECK_32(m);

                        /*
                         * Recompute IP and UDP header pointers for new mbuf
                         */
                        ip6 = mtod(m, struct ip6_hdr *);
                        uh = (struct udphdr *)(void *)((caddr_t)ip6 + off);
                }
                lck_rw_done(pcbinfo->ipi_lock);

                if (mcast_delivered == 0) {
                        /*
                         * No matching pcb found; discard datagram.
                         * (No need to send an ICMP Port Unreachable
                         * for a broadcast or multicast datgram.)
                         */
                        udpstat.udps_noport++;
                        udpstat.udps_noportmcast++;
                        IF_UDP_STATINC(ifp, port_unreach);
                        goto bad;
                }

                /* free the extra copy of mbuf or skipped by NECP */
                if (m != NULL) {
                        m_freem(m);
                }
                return IPPROTO_DONE;
        }

#if IPSEC
        /*
         * UDP to port 4500 with a payload where the first four bytes are
         * not zero is a UDP encapsulated IPsec packet. Packets where
         * the payload is one byte and that byte is 0xFF are NAT keepalive
         * packets. Decapsulate the ESP packet and carry on with IPsec input
         * or discard the NAT keep-alive.
         */
        if (ipsec_bypass == 0 && (esp_udp_encap_port & 0xFFFF) != 0 &&
            (uh->uh_dport == ntohs((u_short)esp_udp_encap_port) ||
            uh->uh_sport == ntohs((u_short)esp_udp_encap_port))) {
                /*
                 * Check if ESP or keepalive:
                 *      1. If the destination port of the incoming packet is 4500.
                 *      2. If the source port of the incoming packet is 4500,
                 *         then check the SADB to match IP address and port.
                 */
                bool check_esp = true;
                if (uh->uh_dport != ntohs((u_short)esp_udp_encap_port)) {
                        check_esp = key_checksa_present(AF_INET6, (caddr_t)&ip6->ip6_dst,
                            (caddr_t)&ip6->ip6_src, uh->uh_dport,
                            uh->uh_sport);
                }

                if (check_esp) {
                        int payload_len = ulen - sizeof(struct udphdr) > 4 ? 4 :
                            ulen - sizeof(struct udphdr);

                        if (m->m_len < off + sizeof(struct udphdr) + payload_len) {
                                if ((m = m_pullup(m, off + sizeof(struct udphdr) +
                                    payload_len)) == NULL) {
                                        udpstat.udps_hdrops++;
                                        goto bad;
                                }
                                /*
                                 * Expect 32-bit aligned data pointer on strict-align
                                 * platforms.
                                 */
                                MBUF_STRICT_DATA_ALIGNMENT_CHECK_32(m);

                                ip6 = mtod(m, struct ip6_hdr *);
                                uh = (struct udphdr *)(void *)((caddr_t)ip6 + off);
                        }
                        /* Check for NAT keepalive packet */
                        if (payload_len == 1 && *(u_int8_t*)
                            ((caddr_t)uh + sizeof(struct udphdr)) == 0xFF) {
                                goto bad;
                        } else if (payload_len == 4 && *(u_int32_t*)(void *)
                            ((caddr_t)uh + sizeof(struct udphdr)) != 0) {
                                /* UDP encapsulated IPsec packet to pass through NAT */
                                /* preserve the udp header */
                                *offp = off + sizeof(struct udphdr);
                                return esp6_input(mp, offp, IPPROTO_UDP);
                        }
                }
        }
#endif /* IPSEC */

        /*
         * Locate pcb for datagram.
         */
        in6p = in6_pcblookup_hash(&udbinfo, &ip6->ip6_src, uh->uh_sport,
            &ip6->ip6_dst, uh->uh_dport, 1, m->m_pkthdr.rcvif);
        if (in6p == NULL) {
                IF_UDP_STATINC(ifp, port_unreach);

                if (udp_log_in_vain) {
                        char buf[INET6_ADDRSTRLEN];

                        strlcpy(buf, ip6_sprintf(&ip6->ip6_dst), sizeof(buf));
                        if (udp_log_in_vain < 3) {
                                log(LOG_INFO, "Connection attempt to UDP "
                                    "%s:%d from %s:%d\n", buf,
                                    ntohs(uh->uh_dport),
                                    ip6_sprintf(&ip6->ip6_src),
                                    ntohs(uh->uh_sport));
                        } else if (!(m->m_flags & (M_BCAST | M_MCAST)) &&
                            !IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &ip6->ip6_src)) {
                                log(LOG_INFO, "Connection attempt "
                                    "to UDP %s:%d from %s:%d\n", buf,
                                    ntohs(uh->uh_dport),
                                    ip6_sprintf(&ip6->ip6_src),
                                    ntohs(uh->uh_sport));
                        }
                }
                udpstat.udps_noport++;
                if (m->m_flags & M_MCAST) {
                        printf("UDP6: M_MCAST is set in a unicast packet.\n");
                        udpstat.udps_noportmcast++;
                        IF_UDP_STATINC(ifp, badmcast);
                        goto bad;
                }
                icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_NOPORT, 0);
                return IPPROTO_DONE;
        }
#if NECP
        if (!necp_socket_is_allowed_to_send_recv_v6(in6p, uh->uh_dport,
            uh->uh_sport, &ip6->ip6_dst, &ip6->ip6_src, ifp, pf_tag, NULL, NULL, NULL, NULL)) {
                in_pcb_checkstate(in6p, WNT_RELEASE, 0);
                IF_UDP_STATINC(ifp, badipsec);
                goto bad;
        }
#endif /* NECP */

        /*
         * Construct sockaddr format source address.
         * Stuff source address and datagram in user buffer.
         */
        udp_lock(in6p->in6p_socket, 1, 0);

        if (in_pcb_checkstate(in6p, WNT_RELEASE, 1) == WNT_STOPUSING) {
                udp_unlock(in6p->in6p_socket, 1, 0);
                IF_UDP_STATINC(ifp, cleanup);
                goto bad;
        }

        init_sin6(&udp_in6, m); /* general init */
        udp_in6.sin6_port = uh->uh_sport;
        if ((in6p->in6p_flags & INP_CONTROLOPTS) != 0 ||
#if CONTENT_FILTER
            /* Content Filter needs to see local address */
            (in6p->in6p_socket->so_cfil_db != NULL) ||
#endif
            (in6p->in6p_socket->so_options & SO_TIMESTAMP) != 0 ||
            (in6p->in6p_socket->so_options & SO_TIMESTAMP_MONOTONIC) != 0 ||
            (in6p->in6p_socket->so_options & SO_TIMESTAMP_CONTINUOUS) != 0) {
                ret = ip6_savecontrol(in6p, m, &opts);
                if (ret != 0) {
                        udp_unlock(in6p->in6p_socket, 1, 0);
                        goto bad;
                }
        }
        m_adj(m, off + sizeof(struct udphdr));
        if (nstat_collect) {
                INP_ADD_STAT(in6p, cell, wifi, wired, rxpackets, 1);
                INP_ADD_STAT(in6p, cell, wifi, wired, rxbytes, m->m_pkthdr.len);
                inp_set_activity_bitmap(in6p);
        }
        so_recv_data_stat(in6p->in6p_socket, m, 0);
        if (sbappendaddr(&in6p->in6p_socket->so_rcv,
            (struct sockaddr *)&udp_in6, m, opts, NULL) == 0) {
                m = NULL;
                opts = NULL;
                udpstat.udps_fullsock++;
                udp_unlock(in6p->in6p_socket, 1, 0);
                goto bad;
        }
        sorwakeup(in6p->in6p_socket);
        udp_unlock(in6p->in6p_socket, 1, 0);
        return IPPROTO_DONE;
bad:
        if (m != NULL) {
                m_freem(m);
        }
        if (opts != NULL) {
                m_freem(opts);
        }
        return IPPROTO_DONE;
}

void
udp6_ctlinput(int cmd, struct sockaddr *sa, void *d, __unused struct ifnet *ifp)
{
        struct udphdr uh;
        struct ip6_hdr *ip6;
        struct mbuf *m;
        int off = 0;
        struct ip6ctlparam *ip6cp = NULL;
        struct icmp6_hdr *icmp6 = NULL;
        const struct sockaddr_in6 *sa6_src = NULL;
        void *cmdarg = NULL;
        void (*notify)(struct inpcb *, int) = udp_notify;
        struct inpcb *in6p;
        struct udp_portonly {
                u_int16_t uh_sport;
                u_int16_t uh_dport;
        } *uhp;

        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 = in6_rtchange;
                d = NULL;
        } else if (cmd == PRC_HOSTDEAD) {
                d = NULL;
        } else if (inet6ctlerrmap[cmd] == 0) {
                return;
        }

        /* if the parameter is from icmp6, decode it. */
        if (d != NULL) {
                ip6cp = (struct ip6ctlparam *)d;
                icmp6 = ip6cp->ip6c_icmp6;
                m = ip6cp->ip6c_m;
                ip6 = ip6cp->ip6c_ip6;
                off = ip6cp->ip6c_off;
                cmdarg = ip6cp->ip6c_cmdarg;
                sa6_src = ip6cp->ip6c_src;
        } else {
                m = NULL;
                ip6 = NULL;
                cmdarg = NULL;
                sa6_src = &sa6_any;
        }

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

                in6p = in6_pcblookup_hash(&udbinfo, &ip6->ip6_dst, uh.uh_dport,
                    &ip6->ip6_src, uh.uh_sport, 0, NULL);
                if (cmd == PRC_MSGSIZE && in6p != NULL && !uuid_is_null(in6p->necp_client_uuid)) {
                        uuid_t null_uuid;
                        uuid_clear(null_uuid);
                        necp_update_flow_protoctl_event(null_uuid, in6p->necp_client_uuid,
                            PRC_MSGSIZE, ntohl(icmp6->icmp6_mtu), 0);
                }

                (void) in6_pcbnotify(&udbinfo, sa, uh.uh_dport,
                    (struct sockaddr*)ip6cp->ip6c_src, uh.uh_sport,
                    cmd, cmdarg, notify);
        }
        /*
         * XXX The else condition here was broken for a long time.
         * Fixing it made us deliver notification correctly but broke
         * some frameworks that didn't handle it well.
         * For now we have removed it and will revisit it later.
         */
}

static int
udp6_abort(struct socket *so)
{
        struct inpcb *inp;

        inp = sotoinpcb(so);
        if (inp == NULL) {
                panic("%s: so=%p null inp\n", __func__, so);
                /* NOTREACHED */
        }
        soisdisconnected(so);
        in6_pcbdetach(inp);
        return 0;
}

static int
udp6_attach(struct socket *so, int proto, struct proc *p)
{
#pragma unused(proto)
        struct inpcb *inp;
        int error;

        inp = sotoinpcb(so);
        if (inp != NULL) {
                return EINVAL;
        }

        error = in_pcballoc(so, &udbinfo, p);
        if (error) {
                return error;
        }

        if (so->so_snd.sb_hiwat == 0 || so->so_rcv.sb_hiwat == 0) {
                error = soreserve(so, udp_sendspace, udp_recvspace);
                if (error) {
                        return error;
                }
        }
        inp = (struct inpcb *)so->so_pcb;
        inp->inp_vflag |= INP_IPV6;
        if (ip6_mapped_addr_on) {
                inp->inp_vflag |= INP_IPV4;
        }
        inp->in6p_hops = -1;    /* use kernel default */
        inp->in6p_cksum = -1;   /* just to be sure */
        /*
         * XXX: ugly!!
         * IPv4 TTL initialization is necessary for an IPv6 socket as well,
         * because the socket may be bound to an IPv6 wildcard address,
         * which may match an IPv4-mapped IPv6 address.
         */
        inp->inp_ip_ttl = (u_char)ip_defttl;
        if (nstat_collect) {
                nstat_udp_new_pcb(inp);
        }
        return 0;
}

static int
udp6_bind(struct socket *so, struct sockaddr *nam, struct proc *p)
{
        struct inpcb *inp;
        int error;

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

        inp->inp_vflag &= ~INP_IPV4;
        inp->inp_vflag |= INP_IPV6;
        if ((inp->inp_flags & IN6P_IPV6_V6ONLY) == 0) {
                struct sockaddr_in6 *sin6_p;

                sin6_p = (struct sockaddr_in6 *)(void *)nam;

                if (IN6_IS_ADDR_UNSPECIFIED(&sin6_p->sin6_addr)) {
                        inp->inp_vflag |= INP_IPV4;
                } else if (IN6_IS_ADDR_V4MAPPED(&sin6_p->sin6_addr)) {
                        struct sockaddr_in sin;

                        in6_sin6_2_sin(&sin, sin6_p);
                        inp->inp_vflag |= INP_IPV4;
                        inp->inp_vflag &= ~INP_IPV6;
                        error = in_pcbbind(inp, (struct sockaddr *)&sin, p);
                        return error;
                }
        }

        error = in6_pcbbind(inp, nam, p);
        return error;
}

int
udp6_connect(struct socket *so, struct sockaddr *nam, struct proc *p)
{
        struct inpcb *inp;
        int error;
#if defined(NECP) && defined(FLOW_DIVERT)
        int should_use_flow_divert = 0;
#endif /* defined(NECP) && defined(FLOW_DIVERT) */

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

#if defined(NECP) && defined(FLOW_DIVERT)
        should_use_flow_divert = necp_socket_should_use_flow_divert(inp);
#endif /* defined(NECP) && defined(FLOW_DIVERT) */

        if ((inp->inp_flags & IN6P_IPV6_V6ONLY) == 0) {
                struct sockaddr_in6 *sin6_p;

                sin6_p = (struct sockaddr_in6 *)(void *)nam;
                if (IN6_IS_ADDR_V4MAPPED(&sin6_p->sin6_addr)) {
                        struct sockaddr_in sin;

                        if (inp->inp_faddr.s_addr != INADDR_ANY) {
                                return EISCONN;
                        }

                        if (!(so->so_flags1 & SOF1_CONNECT_COUNTED)) {
                                so->so_flags1 |= SOF1_CONNECT_COUNTED;
                                INC_ATOMIC_INT64_LIM(net_api_stats.nas_socket_inet_dgram_connected);
                        }

                        in6_sin6_2_sin(&sin, sin6_p);
#if defined(NECP) && defined(FLOW_DIVERT)
                        if (should_use_flow_divert) {
                                goto do_flow_divert;
                        }
#endif /* defined(NECP) && defined(FLOW_DIVERT) */
                        error = in_pcbconnect(inp, (struct sockaddr *)&sin,
                            p, IFSCOPE_NONE, NULL);
                        if (error == 0) {
#if NECP
                                /* Update NECP client with connected five-tuple */
                                if (!uuid_is_null(inp->necp_client_uuid)) {
                                        socket_unlock(so, 0);
                                        necp_client_assign_from_socket(so->last_pid, inp->necp_client_uuid, inp);
                                        socket_lock(so, 0);
                                }
#endif /* NECP */
                                inp->inp_vflag |= INP_IPV4;
                                inp->inp_vflag &= ~INP_IPV6;
                                soisconnected(so);
                        }
                        return error;
                }
        }

        if (!IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_faddr)) {
                return EISCONN;
        }

        if (!(so->so_flags1 & SOF1_CONNECT_COUNTED)) {
                so->so_flags1 |= SOF1_CONNECT_COUNTED;
                INC_ATOMIC_INT64_LIM(net_api_stats.nas_socket_inet6_dgram_connected);
        }

#if defined(NECP) && defined(FLOW_DIVERT)
do_flow_divert:
        if (should_use_flow_divert) {
                error = flow_divert_pcb_init(so);
                if (error == 0) {
                        error = flow_divert_connect_out(so, nam, p);
                }
                return error;
        }
#endif /* defined(NECP) && defined(FLOW_DIVERT) */

        error = in6_pcbconnect(inp, nam, p);
        if (error == 0) {
                /* should be non mapped addr */
                if (ip6_mapped_addr_on ||
                    (inp->inp_flags & IN6P_IPV6_V6ONLY) == 0) {
                        inp->inp_vflag &= ~INP_IPV4;
                        inp->inp_vflag |= INP_IPV6;
                }
#if NECP
                /* Update NECP client with connected five-tuple */
                if (!uuid_is_null(inp->necp_client_uuid)) {
                        socket_unlock(so, 0);
                        necp_client_assign_from_socket(so->last_pid, inp->necp_client_uuid, inp);
                        socket_lock(so, 0);
                }
#endif /* NECP */
                soisconnected(so);
                if (inp->inp_flowhash == 0) {
                        inp->inp_flowhash = inp_calc_flowhash(inp);
                }
                /* update flowinfo - RFC 6437 */
                if (inp->inp_flow == 0 &&
                    inp->in6p_flags & IN6P_AUTOFLOWLABEL) {
                        inp->inp_flow &= ~IPV6_FLOWLABEL_MASK;
                        inp->inp_flow |=
                            (htonl(inp->inp_flowhash) & IPV6_FLOWLABEL_MASK);
                }
        }
        return error;
}

static int
udp6_connectx(struct socket *so, struct sockaddr *src,
    struct sockaddr *dst, struct proc *p, uint32_t ifscope,
    sae_associd_t aid, sae_connid_t *pcid, uint32_t flags, void *arg,
    uint32_t arglen, struct uio *uio, user_ssize_t *bytes_written)
{
        return udp_connectx_common(so, AF_INET6, src, dst,
                   p, ifscope, aid, pcid, flags, arg, arglen, uio, bytes_written);
}

static int
udp6_detach(struct socket *so)
{
        struct inpcb *inp;

        inp = sotoinpcb(so);
        if (inp == NULL) {
                return EINVAL;
        }
        in6_pcbdetach(inp);
        return 0;
}

static int
udp6_disconnect(struct socket *so)
{
        struct inpcb *inp;

        inp = sotoinpcb(so);
        if (inp == NULL
#if NECP
            || (necp_socket_should_use_flow_divert(inp))
#endif /* NECP */
            ) {
                return inp == NULL ? EINVAL : EPROTOTYPE;
        }

        if (inp->inp_vflag & INP_IPV4) {
                struct pr_usrreqs *pru;

                pru = ip_protox[IPPROTO_UDP]->pr_usrreqs;
                return (*pru->pru_disconnect)(so);
        }

        if (IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_faddr)) {
                return ENOTCONN;
        }

        in6_pcbdisconnect(inp);

        /* reset flow-controlled state, just in case */
        inp_reset_fc_state(inp);

        inp->in6p_laddr = in6addr_any;
        inp->in6p_last_outifp = NULL;

        so->so_state &= ~SS_ISCONNECTED;                /* XXX */
        return 0;
}

static int
udp6_disconnectx(struct socket *so, sae_associd_t aid, sae_connid_t cid)
{
#pragma unused(cid)
        if (aid != SAE_ASSOCID_ANY && aid != SAE_ASSOCID_ALL) {
                return EINVAL;
        }

        return udp6_disconnect(so);
}

static int
udp6_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *addr,
    struct mbuf *control, struct proc *p)
{
        struct inpcb *inp;
        int error = 0;
#if defined(NECP) && defined(FLOW_DIVERT)
        int should_use_flow_divert = 0;
#endif /* defined(NECP) && defined(FLOW_DIVERT) */
#if CONTENT_FILTER
        struct m_tag *cfil_tag = NULL;
        struct sockaddr *cfil_faddr = NULL;
#endif

        inp = sotoinpcb(so);
        if (inp == NULL) {
                error = EINVAL;
                goto bad;
        }

#if CONTENT_FILTER
        //If socket is subject to UDP Content Filter and unconnected, get addr from tag.
        if (so->so_cfil_db && !addr && IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_faddr)) {
                cfil_tag = cfil_dgram_get_socket_state(m, NULL, NULL, &cfil_faddr, NULL);
                if (cfil_tag) {
                        addr = (struct sockaddr *)cfil_faddr;
                }
        }
#endif

#if defined(NECP) && defined(FLOW_DIVERT)
        should_use_flow_divert = necp_socket_should_use_flow_divert(inp);
#endif /* defined(NECP) && defined(FLOW_DIVERT) */

        if (addr != NULL) {
                if (addr->sa_len != sizeof(struct sockaddr_in6)) {
                        error = EINVAL;
                        goto bad;
                }
                if (addr->sa_family != AF_INET6) {
                        error = EAFNOSUPPORT;
                        goto bad;
                }
        }

        if (ip6_mapped_addr_on || (inp->inp_flags & IN6P_IPV6_V6ONLY) == 0) {
                int hasv4addr;
                struct sockaddr_in6 *sin6 = NULL;

                if (addr == NULL) {
                        hasv4addr = (inp->inp_vflag & INP_IPV4);
                } else {
                        sin6 = (struct sockaddr_in6 *)(void *)addr;
                        hasv4addr =
                            IN6_IS_ADDR_V4MAPPED(&sin6->sin6_addr) ? 1 : 0;
                }
                if (hasv4addr) {
                        struct pr_usrreqs *pru;

                        if (sin6 != NULL) {
                                in6_sin6_2_sin_in_sock(addr);
                        }
#if defined(NECP) && defined(FLOW_DIVERT)
                        if (should_use_flow_divert) {
                                goto do_flow_divert;
                        }
#endif /* defined(NECP) && defined(FLOW_DIVERT) */
                        pru = ip_protox[IPPROTO_UDP]->pr_usrreqs;
                        error = ((*pru->pru_send)(so, flags, m, addr,
                            control, p));
#if CONTENT_FILTER
                        if (cfil_tag) {
                                m_tag_free(cfil_tag);
                        }
#endif
                        /* addr will just be freed in sendit(). */
                        return error;
                }
        }

#if defined(NECP) && defined(FLOW_DIVERT)
do_flow_divert:
        if (should_use_flow_divert) {
                /* Implicit connect */
                error = flow_divert_implicit_data_out(so, flags, m, addr, control, p);
#if CONTENT_FILTER
                if (cfil_tag) {
                        m_tag_free(cfil_tag);
                }
#endif
                return error;
        }
#endif /* defined(NECP) && defined(FLOW_DIVERT) */

        error = udp6_output(inp, m, addr, control, p);
#if CONTENT_FILTER
        if (cfil_tag) {
                m_tag_free(cfil_tag);
        }
#endif
        return error;

bad:
        VERIFY(error != 0);

        if (m != NULL) {
                m_freem(m);
        }
        if (control != NULL) {
                m_freem(control);
        }
#if CONTENT_FILTER
        if (cfil_tag) {
                m_tag_free(cfil_tag);
        }
#endif
        return error;
}

/*
 * Checksum extended UDP header and data.
 */
static int
udp6_input_checksum(struct mbuf *m, struct udphdr *uh, int off, int ulen)
{
        struct ifnet *ifp = m->m_pkthdr.rcvif;
        struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);

        if (!(m->m_pkthdr.csum_flags & CSUM_DATA_VALID) &&
            uh->uh_sum == 0) {
                /* UDP/IPv6 checksum is mandatory (RFC2460) */

                /*
                 * If checksum was already validated, ignore this check.
                 * This is necessary for transport-mode ESP, which may be
                 * getting UDP payloads without checksums when the network
                 * has a NAT64.
                 */
                udpstat.udps_nosum++;
                goto badsum;
        }

        if ((hwcksum_rx || (ifp->if_flags & IFF_LOOPBACK) ||
            (m->m_pkthdr.pkt_flags & PKTF_LOOP)) &&
            (m->m_pkthdr.csum_flags & CSUM_DATA_VALID)) {
                if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) {
                        uh->uh_sum = m->m_pkthdr.csum_rx_val;
                } else {
                        uint32_t sum = m->m_pkthdr.csum_rx_val;
                        uint32_t start = m->m_pkthdr.csum_rx_start;
                        int32_t trailer = (m_pktlen(m) - (off + ulen));

                        /*
                         * Perform 1's complement adjustment of octets
                         * that got included/excluded in the hardware-
                         * calculated checksum value.  Also take care
                         * of any trailing bytes and subtract out
                         * their partial sum.
                         */
                        ASSERT(trailer >= 0);
                        if ((m->m_pkthdr.csum_flags & CSUM_PARTIAL) &&
                            (start != off || trailer != 0)) {
                                uint32_t swbytes = (uint32_t)trailer;
                                uint16_t s = 0, d = 0;

                                if (IN6_IS_SCOPE_EMBED(&ip6->ip6_src)) {
                                        s = ip6->ip6_src.s6_addr16[1];
                                        ip6->ip6_src.s6_addr16[1] = 0;
                                }
                                if (IN6_IS_SCOPE_EMBED(&ip6->ip6_dst)) {
                                        d = ip6->ip6_dst.s6_addr16[1];
                                        ip6->ip6_dst.s6_addr16[1] = 0;
                                }

                                /* callee folds in sum */
                                sum = m_adj_sum16(m, start, off, ulen, sum);
                                if (off > start) {
                                        swbytes += (off - start);
                                } else {
                                        swbytes += (start - off);
                                }

                                if (IN6_IS_SCOPE_EMBED(&ip6->ip6_src)) {
                                        ip6->ip6_src.s6_addr16[1] = s;
                                }
                                if (IN6_IS_SCOPE_EMBED(&ip6->ip6_dst)) {
                                        ip6->ip6_dst.s6_addr16[1] = d;
                                }

                                if (swbytes != 0) {
                                        udp_in_cksum_stats(swbytes);
                                }
                                if (trailer != 0) {
                                        m_adj(m, -trailer);
                                }
                        }

                        uh->uh_sum = in6_pseudo(&ip6->ip6_src, &ip6->ip6_dst,
                            sum + htonl(ulen + IPPROTO_UDP));
                }
                uh->uh_sum ^= 0xffff;
        } else {
                udp_in6_cksum_stats(ulen);
                uh->uh_sum = in6_cksum(m, IPPROTO_UDP, off, ulen);
        }

        if (uh->uh_sum != 0) {
badsum:
                udpstat.udps_badsum++;
                IF_UDP_STATINC(ifp, badchksum);
                return -1;
        }

        return 0;
}