[apple/xnu.git] / bsd / netinet / udp_usrreq.c

/*
 * Copyright (c) 2000-2016 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@
 */
/*
 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. 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_usrreq.c        8.6 (Berkeley) 5/23/95
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/domain.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/sysctl.h>
#include <sys/syslog.h>
#include <sys/mcache.h>
#include <net/ntstat.h>

#include <kern/zalloc.h>
#include <mach/boolean.h>

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

#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/in_tclass.h>
#include <netinet/ip.h>
#if INET6
#include <netinet/ip6.h>
#endif /* INET6 */
#include <netinet/in_pcb.h>
#include <netinet/in_var.h>
#include <netinet/ip_var.h>
#if INET6
#include <netinet6/in6_pcb.h>
#include <netinet6/ip6_var.h>
#include <netinet6/udp6_var.h>
#endif /* INET6 */
#include <netinet/ip_icmp.h>
#include <netinet/icmp_var.h>
#include <netinet/udp.h>
#include <netinet/udp_var.h>
#include <sys/kdebug.h>

#if IPSEC
#include <netinet6/ipsec.h>
#include <netinet6/esp.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 */

#define DBG_LAYER_IN_BEG        NETDBG_CODE(DBG_NETUDP, 0)
#define DBG_LAYER_IN_END        NETDBG_CODE(DBG_NETUDP, 2)
#define DBG_LAYER_OUT_BEG       NETDBG_CODE(DBG_NETUDP, 1)
#define DBG_LAYER_OUT_END       NETDBG_CODE(DBG_NETUDP, 3)
#define DBG_FNC_UDP_INPUT       NETDBG_CODE(DBG_NETUDP, (5 << 8))
#define DBG_FNC_UDP_OUTPUT      NETDBG_CODE(DBG_NETUDP, (6 << 8) | 1)

/*
 * UDP protocol implementation.
 * Per RFC 768, August, 1980.
 */
#ifndef COMPAT_42
static int udpcksum = 1;
#else
static int udpcksum = 0;                /* XXX */
#endif
SYSCTL_INT(_net_inet_udp, UDPCTL_CHECKSUM, checksum,
    CTLFLAG_RW | CTLFLAG_LOCKED, &udpcksum, 0, "");

int udp_log_in_vain = 0;
SYSCTL_INT(_net_inet_udp, OID_AUTO, log_in_vain, CTLFLAG_RW | CTLFLAG_LOCKED,
        &udp_log_in_vain, 0, "Log all incoming UDP packets");

static int blackhole = 0;
SYSCTL_INT(_net_inet_udp, OID_AUTO, blackhole, CTLFLAG_RW | CTLFLAG_LOCKED,
        &blackhole, 0, "Do not send port unreachables for refused connects");

struct inpcbhead udb;           /* from udp_var.h */
#define udb6    udb  /* for KAME src sync over BSD*'s */
struct inpcbinfo udbinfo;

#ifndef UDBHASHSIZE
#define UDBHASHSIZE 16
#endif

/* Garbage collection performed during most recent udp_gc() run */
static boolean_t udp_gc_done = FALSE;

#if IPFIREWALL
extern int fw_verbose;
extern void ipfwsyslog(int level, const char *format, ...);
extern void ipfw_stealth_stats_incr_udp(void);

/* Apple logging, log to ipfw.log */
#define log_in_vain_log(a) {                                            \
        if ((udp_log_in_vain == 3) && (fw_verbose == 2)) {              \
                ipfwsyslog a;                                           \
        } else if ((udp_log_in_vain == 4) && (fw_verbose == 2)) {       \
                ipfw_stealth_stats_incr_udp();                          \
        } else {                                                        \
                log a;                                                  \
        }                                                               \
}
#else /* !IPFIREWALL */
#define log_in_vain_log(a) { log a; }
#endif /* !IPFIREWALL */

static int udp_getstat SYSCTL_HANDLER_ARGS;
struct  udpstat udpstat;        /* from udp_var.h */
SYSCTL_PROC(_net_inet_udp, UDPCTL_STATS, stats,
        CTLTYPE_STRUCT | CTLFLAG_RD | CTLFLAG_LOCKED,
        0, 0, udp_getstat, "S,udpstat",
        "UDP statistics (struct udpstat, netinet/udp_var.h)");

SYSCTL_INT(_net_inet_udp, OID_AUTO, pcbcount,
        CTLFLAG_RD | CTLFLAG_LOCKED, &udbinfo.ipi_count, 0,
        "Number of active PCBs");

__private_extern__ int udp_use_randomport = 1;
SYSCTL_INT(_net_inet_udp, OID_AUTO, randomize_ports,
        CTLFLAG_RW | CTLFLAG_LOCKED, &udp_use_randomport, 0,
        "Randomize UDP port numbers");

#if INET6
struct udp_in6 {
        struct sockaddr_in6     uin6_sin;
        u_char                  uin6_init_done : 1;
};
struct udp_ip6 {
        struct ip6_hdr          uip6_ip6;
        u_char                  uip6_init_done : 1;
};

static int udp_abort(struct socket *);
static int udp_attach(struct socket *, int, struct proc *);
static int udp_bind(struct socket *, struct sockaddr *, struct proc *);
static int udp_connect(struct socket *, struct sockaddr *, struct proc *);
static int udp_connectx(struct socket *, struct sockaddr_list **,
    struct sockaddr_list **, struct proc *, uint32_t, sae_associd_t,
    sae_connid_t *, uint32_t, void *, uint32_t, struct uio *, user_ssize_t *);
static int udp_detach(struct socket *);
static int udp_disconnect(struct socket *);
static int udp_disconnectx(struct socket *, sae_associd_t, sae_connid_t);
static int udp_send(struct socket *, int, struct mbuf *, struct sockaddr *,
    struct mbuf *, struct proc *);
static void udp_append(struct inpcb *, struct ip *, struct mbuf *, int,
    struct sockaddr_in *, struct udp_in6 *, struct udp_ip6 *, struct ifnet *);
#else /* !INET6 */
static void udp_append(struct inpcb *, struct ip *, struct mbuf *, int,
    struct sockaddr_in *, struct ifnet *);
#endif /* !INET6 */
static int udp_input_checksum(struct mbuf *, struct udphdr *, int, int);
static int udp_output(struct inpcb *, struct mbuf *, struct sockaddr *,
    struct mbuf *, struct proc *);
static void ip_2_ip6_hdr(struct ip6_hdr *ip6, struct ip *ip);
static void udp_gc(struct inpcbinfo *);

struct pr_usrreqs udp_usrreqs = {
        .pru_abort =            udp_abort,
        .pru_attach =           udp_attach,
        .pru_bind =             udp_bind,
        .pru_connect =          udp_connect,
        .pru_connectx =         udp_connectx,
        .pru_control =          in_control,
        .pru_detach =           udp_detach,
        .pru_disconnect =       udp_disconnect,
        .pru_disconnectx =      udp_disconnectx,
        .pru_peeraddr =         in_getpeeraddr,
        .pru_send =             udp_send,
        .pru_shutdown =         udp_shutdown,
        .pru_sockaddr =         in_getsockaddr,
        .pru_sosend =           sosend,
        .pru_soreceive =        soreceive,
        .pru_soreceive_list =   soreceive_list,
};

void
udp_init(struct protosw *pp, struct domain *dp)
{
#pragma unused(dp)
        static int udp_initialized = 0;
        vm_size_t               str_size;
        struct inpcbinfo        *pcbinfo;

        VERIFY((pp->pr_flags & (PR_INITIALIZED|PR_ATTACHED)) == PR_ATTACHED);

        if (udp_initialized)
                return;
        udp_initialized = 1;

        LIST_INIT(&udb);
        udbinfo.ipi_listhead = &udb;
        udbinfo.ipi_hashbase = hashinit(UDBHASHSIZE, M_PCB,
            &udbinfo.ipi_hashmask);
        udbinfo.ipi_porthashbase = hashinit(UDBHASHSIZE, M_PCB,
            &udbinfo.ipi_porthashmask);
        str_size = (vm_size_t) sizeof (struct inpcb);
        udbinfo.ipi_zone = zinit(str_size, 80000*str_size, 8192, "udpcb");

        pcbinfo = &udbinfo;
        /*
         * allocate lock group attribute and group for udp pcb mutexes
         */
        pcbinfo->ipi_lock_grp_attr = lck_grp_attr_alloc_init();
        pcbinfo->ipi_lock_grp = lck_grp_alloc_init("udppcb",
            pcbinfo->ipi_lock_grp_attr);
        pcbinfo->ipi_lock_attr = lck_attr_alloc_init();
        if ((pcbinfo->ipi_lock = lck_rw_alloc_init(pcbinfo->ipi_lock_grp,
            pcbinfo->ipi_lock_attr)) == NULL) {
                panic("%s: unable to allocate PCB lock\n", __func__);
                /* NOTREACHED */
        }

        udbinfo.ipi_gc = udp_gc;
        in_pcbinfo_attach(&udbinfo);
}

void
udp_input(struct mbuf *m, int iphlen)
{
        struct ip *ip;
        struct udphdr *uh;
        struct inpcb *inp;
        struct mbuf *opts = NULL;
        int len, isbroadcast;
        struct ip save_ip;
        struct sockaddr *append_sa;
        struct inpcbinfo *pcbinfo = &udbinfo;
        struct sockaddr_in udp_in;
        struct ip_moptions *imo = NULL;
        int foundmembership = 0, ret = 0;
#if INET6
        struct udp_in6 udp_in6;
        struct udp_ip6 udp_ip6;
#endif /* INET6 */
        struct ifnet *ifp = m->m_pkthdr.rcvif;
        boolean_t cell = IFNET_IS_CELLULAR(ifp);
        boolean_t wifi = (!cell && IFNET_IS_WIFI(ifp));
        boolean_t wired = (!wifi && IFNET_IS_WIRED(ifp));

        bzero(&udp_in, sizeof (udp_in));
        udp_in.sin_len = sizeof (struct sockaddr_in);
        udp_in.sin_family = AF_INET;
#if INET6
        bzero(&udp_in6, sizeof (udp_in6));
        udp_in6.uin6_sin.sin6_len = sizeof (struct sockaddr_in6);
        udp_in6.uin6_sin.sin6_family = AF_INET6;
#endif /* INET6 */

        udpstat.udps_ipackets++;

        KERNEL_DEBUG(DBG_FNC_UDP_INPUT | DBG_FUNC_START, 0, 0, 0, 0, 0);

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

        /*
         * Strip IP options, if any; should skip this,
         * make available to user, and use on returned packets,
         * but we don't yet have a way to check the checksum
         * with options still present.
         */
        if (iphlen > sizeof (struct ip)) {
                ip_stripoptions(m, (struct mbuf *)0);
                iphlen = sizeof (struct ip);
        }

        /*
         * Get IP and UDP header together in first mbuf.
         */
        ip = mtod(m, struct ip *);
        if (m->m_len < iphlen + sizeof (struct udphdr)) {
                m = m_pullup(m, iphlen + sizeof (struct udphdr));
                if (m == NULL) {
                        udpstat.udps_hdrops++;
                        KERNEL_DEBUG(DBG_FNC_UDP_INPUT | DBG_FUNC_END,
                            0, 0, 0, 0, 0);
                        return;
                }
                ip = mtod(m, struct ip *);
        }
        uh = (struct udphdr *)(void *)((caddr_t)ip + iphlen);

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

        KERNEL_DEBUG(DBG_LAYER_IN_BEG, uh->uh_dport, uh->uh_sport,
            ip->ip_src.s_addr, ip->ip_dst.s_addr, uh->uh_ulen);

        /*
         * Make mbuf data length reflect UDP length.
         * If not enough data to reflect UDP length, drop.
         */
        len = ntohs((u_short)uh->uh_ulen);
        if (ip->ip_len != len) {
                if (len > ip->ip_len || len < sizeof (struct udphdr)) {
                        udpstat.udps_badlen++;
                        IF_UDP_STATINC(ifp, badlength);
                        goto bad;
                }
                m_adj(m, len - ip->ip_len);
                /* ip->ip_len = len; */
        }
        /*
         * Save a copy of the IP header in case we want restore it
         * for sending an ICMP error message in response.
         */
        save_ip = *ip;

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

        isbroadcast = in_broadcast(ip->ip_dst, ifp);

        if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || isbroadcast) {
                int reuse_sock = 0, mcast_delivered = 0;

                lck_rw_lock_shared(pcbinfo->ipi_lock);
                /*
                 * 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?)
                 */

                /*
                 * Construct sockaddr format source address.
                 */
                udp_in.sin_port = uh->uh_sport;
                udp_in.sin_addr = ip->ip_src;
                /*
                 * Locate pcb(s) for datagram.
                 * (Algorithm copied from raw_intr().)
                 */
#if INET6
                udp_in6.uin6_init_done = udp_ip6.uip6_init_done = 0;
#endif /* INET6 */
                LIST_FOREACH(inp, &udb, inp_list) {
#if IPSEC
                        int skipit;
#endif /* IPSEC */

                        if (inp->inp_socket == NULL)
                                continue;
                        if (inp != sotoinpcb(inp->inp_socket)) {
                                panic("%s: bad so back ptr inp=%p\n",
                                    __func__, inp);
                                /* NOTREACHED */
                        }
#if INET6
                        if ((inp->inp_vflag & INP_IPV4) == 0)
                                continue;
#endif /* INET6 */
                        if (inp_restricted_recv(inp, ifp))
                                continue;

                        if ((inp->inp_moptions == NULL) &&
                            (ntohl(ip->ip_dst.s_addr) !=
                            INADDR_ALLHOSTS_GROUP) && (isbroadcast == 0))
                                continue;

                        if (in_pcb_checkstate(inp, WNT_ACQUIRE, 0) ==
                            WNT_STOPUSING)
                                continue;

                        udp_lock(inp->inp_socket, 1, 0);

                        if (in_pcb_checkstate(inp, WNT_RELEASE, 1) ==
                            WNT_STOPUSING) {
                                udp_unlock(inp->inp_socket, 1, 0);
                                continue;
                        }

                        if (inp->inp_lport != uh->uh_dport) {
                                udp_unlock(inp->inp_socket, 1, 0);
                                continue;
                        }
                        if (inp->inp_laddr.s_addr != INADDR_ANY) {
                                if (inp->inp_laddr.s_addr !=
                                    ip->ip_dst.s_addr) {
                                        udp_unlock(inp->inp_socket, 1, 0);
                                        continue;
                                }
                        }
                        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) {
                                        udp_unlock(inp->inp_socket, 1, 0);
                                        continue;
                                }
                        }

                        if (isbroadcast == 0 && (ntohl(ip->ip_dst.s_addr) !=
                            INADDR_ALLHOSTS_GROUP)) {
                                struct sockaddr_in group;
                                int blocked;

                                if ((imo = inp->inp_moptions) == NULL) {
                                        udp_unlock(inp->inp_socket, 1, 0);
                                        continue;
                                }
                                IMO_LOCK(imo);

                                bzero(&group, sizeof (struct sockaddr_in));
                                group.sin_len = sizeof (struct sockaddr_in);
                                group.sin_family = AF_INET;
                                group.sin_addr = ip->ip_dst;

                                blocked = imo_multi_filter(imo, ifp,
                                    (struct sockaddr *)&group,
                                    (struct sockaddr *)&udp_in);
                                if (blocked == MCAST_PASS)
                                        foundmembership = 1;

                                IMO_UNLOCK(imo);
                                if (!foundmembership) {
                                        udp_unlock(inp->inp_socket, 1, 0);
                                        if (blocked == MCAST_NOTSMEMBER ||
                                            blocked == MCAST_MUTED)
                                                udpstat.udps_filtermcast++;
                                        continue;
                                }
                                foundmembership = 0;
                        }

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

#if NECP
                        skipit = 0;
                        if (!necp_socket_is_allowed_to_send_recv_v4(inp,
                            uh->uh_dport, uh->uh_sport, &ip->ip_dst,
                            &ip->ip_src, ifp, NULL, NULL)) {
                                /* do not inject data to pcb */
                                skipit = 1;
                        }
                        if (skipit == 0)
#endif /* NECP */
                        {
                                struct mbuf *n = NULL;

                                if (reuse_sock)
                                        n = m_copy(m, 0, M_COPYALL);
#if INET6
                                udp_append(inp, ip, m,
                                    iphlen + sizeof (struct udphdr),
                                    &udp_in, &udp_in6, &udp_ip6, ifp);
#else /* !INET6 */
                                udp_append(inp, ip, m,
                                    iphlen + sizeof (struct udphdr),
                                    &udp_in, ifp);
#endif /* !INET6 */
                                mcast_delivered++;

                                m = n;
                        }
                        udp_unlock(inp->inp_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
                         */
                        ip = mtod(m, struct ip *);
                        uh = (struct udphdr *)(void *)((caddr_t)ip + iphlen);
                }
                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_noportbcast++;
                        IF_UDP_STATINC(ifp, port_unreach);
                        goto bad;
                }

                /* free the extra copy of mbuf or skipped by IPSec */
                if (m != NULL)
                        m_freem(m);
                KERNEL_DEBUG(DBG_FNC_UDP_INPUT | DBG_FUNC_END, 0, 0, 0, 0, 0);
                return;
        }

#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)) {
                int payload_len = len - sizeof (struct udphdr) > 4 ? 4 :
                    len - sizeof (struct udphdr);

                if (m->m_len < iphlen + sizeof (struct udphdr) + payload_len) {
                        if ((m = m_pullup(m, iphlen + sizeof (struct udphdr) +
                            payload_len)) == NULL) {
                                udpstat.udps_hdrops++;
                                KERNEL_DEBUG(DBG_FNC_UDP_INPUT | DBG_FUNC_END,
                                    0, 0, 0, 0, 0);
                                return;
                        }
                        /*
                         * Expect 32-bit aligned data pointer on strict-align
                         * platforms.
                         */
                        MBUF_STRICT_DATA_ALIGNMENT_CHECK_32(m);

                        ip = mtod(m, struct ip *);
                        uh = (struct udphdr *)(void *)((caddr_t)ip + iphlen);
                }
                /* Check for NAT keepalive packet */
                if (payload_len == 1 && *(u_int8_t *)
                    ((caddr_t)uh + sizeof (struct udphdr)) == 0xFF) {
                        m_freem(m);
                        KERNEL_DEBUG(DBG_FNC_UDP_INPUT | DBG_FUNC_END,
                            0, 0, 0, 0, 0);
                        return;
                } else if (payload_len == 4 && *(u_int32_t *)(void *)
                    ((caddr_t)uh + sizeof (struct udphdr)) != 0) {
                        /* UDP encapsulated IPSec packet to pass through NAT */
                        KERNEL_DEBUG(DBG_FNC_UDP_INPUT | DBG_FUNC_END,
                            0, 0, 0, 0, 0);
                        /* preserve the udp header */
                        esp4_input(m, iphlen + sizeof (struct udphdr));
                        return;
                }
        }
#endif /* IPSEC */

        /*
         * Locate pcb for datagram.
         */
        inp = in_pcblookup_hash(&udbinfo, ip->ip_src, uh->uh_sport,
            ip->ip_dst, uh->uh_dport, 1, ifp);
        if (inp == NULL) {
                IF_UDP_STATINC(ifp, port_unreach);

                if (udp_log_in_vain) {
                        char buf[MAX_IPv4_STR_LEN];
                        char buf2[MAX_IPv4_STR_LEN];

                        /* check src and dst address */
                        if (udp_log_in_vain < 3) {
                                log(LOG_INFO, "Connection attempt to "
                                    "UDP %s:%d from %s:%d\n", inet_ntop(AF_INET,
                                        &ip->ip_dst, buf, sizeof (buf)),
                                        ntohs(uh->uh_dport), inet_ntop(AF_INET,
                                        &ip->ip_src, buf2, sizeof (buf2)),
                                        ntohs(uh->uh_sport));
                        } else if (!(m->m_flags & (M_BCAST | M_MCAST)) &&
                            ip->ip_dst.s_addr != ip->ip_src.s_addr) {
                                log_in_vain_log((LOG_INFO,
                                    "Stealth Mode connection attempt to "
                                    "UDP %s:%d from %s:%d\n", inet_ntop(AF_INET,
                                    &ip->ip_dst, buf, sizeof (buf)),
                                    ntohs(uh->uh_dport), inet_ntop(AF_INET,
                                    &ip->ip_src, buf2, sizeof (buf2)),
                                    ntohs(uh->uh_sport)))
                        }
                }
                udpstat.udps_noport++;
                if (m->m_flags & (M_BCAST | M_MCAST)) {
                        udpstat.udps_noportbcast++;
                        goto bad;
                }
#if ICMP_BANDLIM
                if (badport_bandlim(BANDLIM_ICMP_UNREACH) < 0)
                        goto bad;
#endif /* ICMP_BANDLIM */
                if (blackhole)
                        if (ifp && ifp->if_type != IFT_LOOP)
                                goto bad;
                *ip = save_ip;
                ip->ip_len += iphlen;
                icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_PORT, 0, 0);
                KERNEL_DEBUG(DBG_FNC_UDP_INPUT | DBG_FUNC_END, 0, 0, 0, 0, 0);
                return;
        }
        udp_lock(inp->inp_socket, 1, 0);

        if (in_pcb_checkstate(inp, WNT_RELEASE, 1) == WNT_STOPUSING) {
                udp_unlock(inp->inp_socket, 1, 0);
                IF_UDP_STATINC(ifp, cleanup);
                goto bad;
        }
#if NECP
        if (!necp_socket_is_allowed_to_send_recv_v4(inp, uh->uh_dport,
            uh->uh_sport, &ip->ip_dst, &ip->ip_src, ifp, NULL, NULL)) {
                udp_unlock(inp->inp_socket, 1, 0);
                IF_UDP_STATINC(ifp, badipsec);
                goto bad;
        }
#endif /* NECP */

        /*
         * Construct sockaddr format source address.
         * Stuff source address and datagram in user buffer.
         */
        udp_in.sin_port = uh->uh_sport;
        udp_in.sin_addr = ip->ip_src;
        if ((inp->inp_flags & INP_CONTROLOPTS) != 0 ||
            (inp->inp_socket->so_options & SO_TIMESTAMP) != 0 ||
            (inp->inp_socket->so_options & SO_TIMESTAMP_MONOTONIC) != 0) {
#if INET6
                if (inp->inp_vflag & INP_IPV6) {
                        int savedflags;

                        ip_2_ip6_hdr(&udp_ip6.uip6_ip6, ip);
                        savedflags = inp->inp_flags;
                        inp->inp_flags &= ~INP_UNMAPPABLEOPTS;
                        ret = ip6_savecontrol(inp, m, &opts);
                        inp->inp_flags = savedflags;
                } else
#endif /* INET6 */
                {
                        ret = ip_savecontrol(inp, &opts, ip, m);
                }
                if (ret != 0) {
                        udp_unlock(inp->inp_socket, 1, 0);
                        goto bad;
                }
        }
        m_adj(m, iphlen + sizeof (struct udphdr));

        KERNEL_DEBUG(DBG_LAYER_IN_END, uh->uh_dport, uh->uh_sport,
            save_ip.ip_src.s_addr, save_ip.ip_dst.s_addr, uh->uh_ulen);

#if INET6
        if (inp->inp_vflag & INP_IPV6) {
                in6_sin_2_v4mapsin6(&udp_in, &udp_in6.uin6_sin);
                append_sa = (struct sockaddr *)&udp_in6.uin6_sin;
        } else
#endif /* INET6 */
        {
                append_sa = (struct sockaddr *)&udp_in;
        }
        if (nstat_collect) {
                INP_ADD_STAT(inp, cell, wifi, wired, rxpackets, 1);
                INP_ADD_STAT(inp, cell, wifi, wired, rxbytes, m->m_pkthdr.len);
        }
        so_recv_data_stat(inp->inp_socket, m, 0);
        if (sbappendaddr(&inp->inp_socket->so_rcv, append_sa,
            m, opts, NULL) == 0) {
                udpstat.udps_fullsock++;
        } else {
                sorwakeup(inp->inp_socket);
        }
        udp_unlock(inp->inp_socket, 1, 0);
        KERNEL_DEBUG(DBG_FNC_UDP_INPUT | DBG_FUNC_END, 0, 0, 0, 0, 0);
        return;
bad:
        m_freem(m);
        if (opts)
                m_freem(opts);
        KERNEL_DEBUG(DBG_FNC_UDP_INPUT | DBG_FUNC_END, 0, 0, 0, 0, 0);
}

#if INET6
static void
ip_2_ip6_hdr(struct ip6_hdr *ip6, struct ip *ip)
{
        bzero(ip6, sizeof (*ip6));

        ip6->ip6_vfc = IPV6_VERSION;
        ip6->ip6_plen = ip->ip_len;
        ip6->ip6_nxt = ip->ip_p;
        ip6->ip6_hlim = ip->ip_ttl;
        if (ip->ip_src.s_addr) {
                ip6->ip6_src.s6_addr32[2] = IPV6_ADDR_INT32_SMP;
                ip6->ip6_src.s6_addr32[3] = ip->ip_src.s_addr;
        }
        if (ip->ip_dst.s_addr) {
                ip6->ip6_dst.s6_addr32[2] = IPV6_ADDR_INT32_SMP;
                ip6->ip6_dst.s6_addr32[3] = ip->ip_dst.s_addr;
        }
}
#endif /* INET6 */

/*
 * subroutine of udp_input(), mainly for source code readability.
 */
static void
#if INET6
udp_append(struct inpcb *last, struct ip *ip, struct mbuf *n, int off,
    struct sockaddr_in *pudp_in, struct udp_in6 *pudp_in6,
    struct udp_ip6 *pudp_ip6, struct ifnet *ifp)
#else /* !INET6 */
udp_append(struct inpcb *last, struct ip *ip, struct mbuf *n, int off,
    struct sockaddr_in *pudp_in, struct ifnet *ifp)
#endif /* !INET6 */
{
        struct sockaddr *append_sa;
        struct mbuf *opts = 0;
        boolean_t cell = IFNET_IS_CELLULAR(ifp);
        boolean_t wifi = (!cell && IFNET_IS_WIFI(ifp));
        boolean_t wired = (!wifi && IFNET_IS_WIRED(ifp));
        int ret = 0;

#if CONFIG_MACF_NET
        if (mac_inpcb_check_deliver(last, n, AF_INET, SOCK_DGRAM) != 0) {
                m_freem(n);
                return;
        }
#endif /* CONFIG_MACF_NET */
        if ((last->inp_flags & INP_CONTROLOPTS) != 0 ||
            (last->inp_socket->so_options & SO_TIMESTAMP) != 0 ||
            (last->inp_socket->so_options & SO_TIMESTAMP_MONOTONIC) != 0) {
#if INET6
                if (last->inp_vflag & INP_IPV6) {
                        int savedflags;

                        if (pudp_ip6->uip6_init_done == 0) {
                                ip_2_ip6_hdr(&pudp_ip6->uip6_ip6, ip);
                                pudp_ip6->uip6_init_done = 1;
                        }
                        savedflags = last->inp_flags;
                        last->inp_flags &= ~INP_UNMAPPABLEOPTS;
                        ret = ip6_savecontrol(last, n, &opts);
                        if (ret != 0) {
                                last->inp_flags = savedflags;
                                goto error;
                        }
                        last->inp_flags = savedflags;
                } else
#endif /* INET6 */
                {
                        ret = ip_savecontrol(last, &opts, ip, n);
                        if (ret != 0) {
                                goto error;
                        }
                }
        }
#if INET6
        if (last->inp_vflag & INP_IPV6) {
                if (pudp_in6->uin6_init_done == 0) {
                        in6_sin_2_v4mapsin6(pudp_in, &pudp_in6->uin6_sin);
                        pudp_in6->uin6_init_done = 1;
                }
                append_sa = (struct sockaddr *)&pudp_in6->uin6_sin;
        } else
#endif /* INET6 */
        append_sa = (struct sockaddr *)pudp_in;
        if (nstat_collect) {
                INP_ADD_STAT(last, cell, wifi, wired, rxpackets, 1);
                INP_ADD_STAT(last, cell, wifi, wired, rxbytes,
                    n->m_pkthdr.len);
        }
        so_recv_data_stat(last->inp_socket, n, 0);
        m_adj(n, off);
        if (sbappendaddr(&last->inp_socket->so_rcv, append_sa,
            n, opts, NULL) == 0) {
                udpstat.udps_fullsock++;
        } else {
                sorwakeup(last->inp_socket);
        }
        return;
error:
        m_freem(n);
        m_freem(opts);
}

/*
 * 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);
}

void
udp_ctlinput(int cmd, struct sockaddr *sa, void *vip)
{
        struct ip *ip = vip;
        void (*notify)(struct inpcb *, int) = udp_notify;
        struct in_addr faddr;
        struct inpcb *inp;

        faddr = ((struct sockaddr_in *)(void *)sa)->sin_addr;
        if (sa->sa_family != AF_INET || faddr.s_addr == INADDR_ANY)
                return;

        if (PRC_IS_REDIRECT(cmd)) {
                ip = 0;
                notify = in_rtchange;
        } else if (cmd == PRC_HOSTDEAD) {
                ip = 0;
        } else if ((unsigned)cmd >= PRC_NCMDS || inetctlerrmap[cmd] == 0) {
                return;
        }
        if (ip) {
                struct udphdr uh;

                bcopy(((caddr_t)ip + (ip->ip_hl << 2)), &uh, sizeof (uh));
                inp = in_pcblookup_hash(&udbinfo, faddr, uh.uh_dport,
                    ip->ip_src, uh.uh_sport, 0, NULL);
                if (inp != NULL && inp->inp_socket != NULL) {
                        udp_lock(inp->inp_socket, 1, 0);
                        if (in_pcb_checkstate(inp, WNT_RELEASE, 1) ==
                            WNT_STOPUSING)  {
                                udp_unlock(inp->inp_socket, 1, 0);
                                return;
                        }
                        (*notify)(inp, inetctlerrmap[cmd]);
                        udp_unlock(inp->inp_socket, 1, 0);
                }
        } else {
                in_pcbnotifyall(&udbinfo, faddr, inetctlerrmap[cmd], notify);
        }
}

int
udp_ctloutput(struct socket *so, struct sockopt *sopt)
{
        int     error, optval;
        struct  inpcb *inp;

        /* Allow <SOL_SOCKET,SO_FLUSH> at this level */
        if (sopt->sopt_level != IPPROTO_UDP &&
            !(sopt->sopt_level == SOL_SOCKET && sopt->sopt_name == SO_FLUSH))
                return (ip_ctloutput(so, sopt));

        error = 0;
        inp = sotoinpcb(so);

        switch (sopt->sopt_dir) {
        case SOPT_SET:
                switch (sopt->sopt_name) {
                case UDP_NOCKSUM:
                        /* This option is settable only for UDP over IPv4 */
                        if (!(inp->inp_vflag & INP_IPV4)) {
                                error = EINVAL;
                                break;
                        }

                        if ((error = sooptcopyin(sopt, &optval, sizeof (optval),
                            sizeof (optval))) != 0)
                                break;

                        if (optval != 0)
                                inp->inp_flags |= INP_UDP_NOCKSUM;
                        else
                                inp->inp_flags &= ~INP_UDP_NOCKSUM;
                        break;
                case UDP_KEEPALIVE_OFFLOAD:
                {
                        struct udp_keepalive_offload ka;
                        /*
                         * If the socket is not connected, the stack will
                         * not know the destination address to put in the
                         * keepalive datagram. Return an error now instead
                         * of failing later.
                         */
                        if (!(so->so_state & SS_ISCONNECTED)) {
                                error = EINVAL;
                                break;
                        }
                        if (sopt->sopt_valsize != sizeof(ka)) {
                                error = EINVAL;
                                break;
                        }
                        if ((error = sooptcopyin(sopt, &ka, sizeof(ka),
                            sizeof(ka))) != 0)
                                break;

                        /* application should specify the type */
                        if (ka.ka_type == 0)
                                return (EINVAL);

                        if (ka.ka_interval == 0) {
                                /*
                                 * if interval is 0, disable the offload
                                 * mechanism
                                 */
                                if (inp->inp_keepalive_data != NULL)
                                        FREE(inp->inp_keepalive_data,
                                            M_TEMP);
                                inp->inp_keepalive_data = NULL;
                                inp->inp_keepalive_datalen = 0;
                                inp->inp_keepalive_interval = 0;
                                inp->inp_keepalive_type = 0;
                                inp->inp_flags2 &= ~INP2_KEEPALIVE_OFFLOAD;
                        } else {
                                if (inp->inp_keepalive_data != NULL) {
                                        FREE(inp->inp_keepalive_data,
                                            M_TEMP);
                                        inp->inp_keepalive_data = NULL;
                                }

                                inp->inp_keepalive_datalen = min(
                                    ka.ka_data_len,
                                    UDP_KEEPALIVE_OFFLOAD_DATA_SIZE);
                                if (inp->inp_keepalive_datalen > 0) {
                                        MALLOC(inp->inp_keepalive_data,
                                            u_int8_t *,
                                            inp->inp_keepalive_datalen,
                                            M_TEMP, M_WAITOK);
                                        if (inp->inp_keepalive_data == NULL) {
                                                inp->inp_keepalive_datalen = 0;
                                                error = ENOMEM;
                                                break;
                                        }
                                        bcopy(ka.ka_data,
                                            inp->inp_keepalive_data,
                                            inp->inp_keepalive_datalen);
                                } else {
                                        inp->inp_keepalive_datalen = 0;
                                }
                                inp->inp_keepalive_interval =
                                    min(UDP_KEEPALIVE_INTERVAL_MAX_SECONDS,
                                    ka.ka_interval);
                                inp->inp_keepalive_type = ka.ka_type;
                                inp->inp_flags2 |= INP2_KEEPALIVE_OFFLOAD;
                        }
                        break;
                }
                case SO_FLUSH:
                        if ((error = sooptcopyin(sopt, &optval, sizeof (optval),
                            sizeof (optval))) != 0)
                                break;

                        error = inp_flush(inp, optval);
                        break;

                default:
                        error = ENOPROTOOPT;
                        break;
                }
                break;

        case SOPT_GET:
                switch (sopt->sopt_name) {
                case UDP_NOCKSUM:
                        optval = inp->inp_flags & INP_UDP_NOCKSUM;
                        break;

                default:
                        error = ENOPROTOOPT;
                        break;
                }
                if (error == 0)
                        error = sooptcopyout(sopt, &optval, sizeof (optval));
                break;
        }
        return (error);
}

static int
udp_pcblist SYSCTL_HANDLER_ARGS
{
#pragma unused(oidp, arg1, arg2)
        int error, i, n;
        struct inpcb *inp, **inp_list;
        inp_gen_t gencnt;
        struct xinpgen xig;

        /*
         * The process of preparing the TCB list is too time-consuming and
         * resource-intensive to repeat twice on every request.
         */
        lck_rw_lock_exclusive(udbinfo.ipi_lock);
        if (req->oldptr == USER_ADDR_NULL) {
                n = udbinfo.ipi_count;
                req->oldidx = 2 * (sizeof (xig))
                        + (n + n/8) * sizeof (struct xinpcb);
                lck_rw_done(udbinfo.ipi_lock);
                return (0);
        }

        if (req->newptr != USER_ADDR_NULL) {
                lck_rw_done(udbinfo.ipi_lock);
                return (EPERM);
        }

        /*
         * OK, now we're committed to doing something.
         */
        gencnt = udbinfo.ipi_gencnt;
        n = udbinfo.ipi_count;

        bzero(&xig, sizeof (xig));
        xig.xig_len = sizeof (xig);
        xig.xig_count = n;
        xig.xig_gen = gencnt;
        xig.xig_sogen = so_gencnt;
        error = SYSCTL_OUT(req, &xig, sizeof (xig));
        if (error) {
                lck_rw_done(udbinfo.ipi_lock);
                return (error);
        }
        /*
         * We are done if there is no pcb
         */
        if (n == 0) {
                lck_rw_done(udbinfo.ipi_lock);
                return (0);
        }

        inp_list = _MALLOC(n * sizeof (*inp_list), M_TEMP, M_WAITOK);
        if (inp_list == 0) {
                lck_rw_done(udbinfo.ipi_lock);
                return (ENOMEM);
        }

        for (inp = LIST_FIRST(udbinfo.ipi_listhead), i = 0; inp && i < n;
            inp = LIST_NEXT(inp, inp_list)) {
                if (inp->inp_gencnt <= gencnt &&
                    inp->inp_state != INPCB_STATE_DEAD)
                        inp_list[i++] = inp;
        }
        n = i;

        error = 0;
        for (i = 0; i < n; i++) {
                struct xinpcb xi;

                inp = inp_list[i];

                if (in_pcb_checkstate(inp, WNT_ACQUIRE, 0) == WNT_STOPUSING)
                        continue;
                udp_lock(inp->inp_socket, 1, 0);
                if (in_pcb_checkstate(inp, WNT_RELEASE, 1) == WNT_STOPUSING) {
                        udp_unlock(inp->inp_socket, 1, 0);
                        continue;
                }
                if (inp->inp_gencnt > gencnt) {
                        udp_unlock(inp->inp_socket, 1, 0);
                        continue;
                }

                bzero(&xi, sizeof (xi));
                xi.xi_len = sizeof (xi);
                /* XXX should avoid extra copy */
                inpcb_to_compat(inp, &xi.xi_inp);
                if (inp->inp_socket)
                        sotoxsocket(inp->inp_socket, &xi.xi_socket);

                udp_unlock(inp->inp_socket, 1, 0);

                error = SYSCTL_OUT(req, &xi, sizeof (xi));
        }
        if (!error) {
                /*
                 * Give the user an updated idea of our state.
                 * If the generation differs from what we told
                 * her before, she knows that something happened
                 * while we were processing this request, and it
                 * might be necessary to retry.
                 */
                bzero(&xig, sizeof (xig));
                xig.xig_len = sizeof (xig);
                xig.xig_gen = udbinfo.ipi_gencnt;
                xig.xig_sogen = so_gencnt;
                xig.xig_count = udbinfo.ipi_count;
                error = SYSCTL_OUT(req, &xig, sizeof (xig));
        }
        FREE(inp_list, M_TEMP);
        lck_rw_done(udbinfo.ipi_lock);
        return (error);
}

SYSCTL_PROC(_net_inet_udp, UDPCTL_PCBLIST, pcblist,
        CTLTYPE_STRUCT | CTLFLAG_RD | CTLFLAG_LOCKED, 0, 0, udp_pcblist,
        "S,xinpcb", "List of active UDP sockets");


static int
udp_pcblist64 SYSCTL_HANDLER_ARGS
{
#pragma unused(oidp, arg1, arg2)
        int error, i, n;
        struct inpcb *inp, **inp_list;
        inp_gen_t gencnt;
        struct xinpgen xig;

        /*
         * The process of preparing the TCB list is too time-consuming and
         * resource-intensive to repeat twice on every request.
         */
        lck_rw_lock_shared(udbinfo.ipi_lock);
        if (req->oldptr == USER_ADDR_NULL) {
                n = udbinfo.ipi_count;
                req->oldidx =
                    2 * (sizeof (xig)) + (n + n/8) * sizeof (struct xinpcb64);
                lck_rw_done(udbinfo.ipi_lock);
                return (0);
        }

        if (req->newptr != USER_ADDR_NULL) {
                lck_rw_done(udbinfo.ipi_lock);
                return (EPERM);
        }

        /*
         * OK, now we're committed to doing something.
         */
        gencnt = udbinfo.ipi_gencnt;
        n = udbinfo.ipi_count;

        bzero(&xig, sizeof (xig));
        xig.xig_len = sizeof (xig);
        xig.xig_count = n;
        xig.xig_gen = gencnt;
        xig.xig_sogen = so_gencnt;
        error = SYSCTL_OUT(req, &xig, sizeof (xig));
        if (error) {
                lck_rw_done(udbinfo.ipi_lock);
                return (error);
        }
        /*
         * We are done if there is no pcb
         */
        if (n == 0) {
                lck_rw_done(udbinfo.ipi_lock);
                return (0);
        }

        inp_list = _MALLOC(n * sizeof (*inp_list), M_TEMP, M_WAITOK);
        if (inp_list == 0) {
                lck_rw_done(udbinfo.ipi_lock);
                return (ENOMEM);
        }

        for (inp = LIST_FIRST(udbinfo.ipi_listhead), i = 0; inp && i < n;
            inp = LIST_NEXT(inp, inp_list)) {
                if (inp->inp_gencnt <= gencnt &&
                    inp->inp_state != INPCB_STATE_DEAD)
                        inp_list[i++] = inp;
        }
        n = i;

        error = 0;
        for (i = 0; i < n; i++) {
                struct xinpcb64 xi;

                inp = inp_list[i];

                if (in_pcb_checkstate(inp, WNT_ACQUIRE, 0) == WNT_STOPUSING)
                        continue;
                udp_lock(inp->inp_socket, 1, 0);
                if (in_pcb_checkstate(inp, WNT_RELEASE, 1) == WNT_STOPUSING) {
                        udp_unlock(inp->inp_socket, 1, 0);
                        continue;
                }
                if (inp->inp_gencnt > gencnt) {
                        udp_unlock(inp->inp_socket, 1, 0);
                        continue;
                }

                bzero(&xi, sizeof (xi));
                xi.xi_len = sizeof (xi);
                inpcb_to_xinpcb64(inp, &xi);
                if (inp->inp_socket)
                        sotoxsocket64(inp->inp_socket, &xi.xi_socket);

                udp_unlock(inp->inp_socket, 1, 0);

                error = SYSCTL_OUT(req, &xi, sizeof (xi));
        }
        if (!error) {
                /*
                 * Give the user an updated idea of our state.
                 * If the generation differs from what we told
                 * her before, she knows that something happened
                 * while we were processing this request, and it
                 * might be necessary to retry.
                 */
                bzero(&xig, sizeof (xig));
                xig.xig_len = sizeof (xig);
                xig.xig_gen = udbinfo.ipi_gencnt;
                xig.xig_sogen = so_gencnt;
                xig.xig_count = udbinfo.ipi_count;
                error = SYSCTL_OUT(req, &xig, sizeof (xig));
        }
        FREE(inp_list, M_TEMP);
        lck_rw_done(udbinfo.ipi_lock);
        return (error);
}

SYSCTL_PROC(_net_inet_udp, OID_AUTO, pcblist64,
        CTLTYPE_STRUCT | CTLFLAG_RD | CTLFLAG_LOCKED, 0, 0, udp_pcblist64,
        "S,xinpcb64", "List of active UDP sockets");


static int
udp_pcblist_n SYSCTL_HANDLER_ARGS
{
#pragma unused(oidp, arg1, arg2)
        return (get_pcblist_n(IPPROTO_UDP, req, &udbinfo));
}

SYSCTL_PROC(_net_inet_udp, OID_AUTO, pcblist_n,
        CTLTYPE_STRUCT | CTLFLAG_RD | CTLFLAG_LOCKED, 0, 0, udp_pcblist_n,
        "S,xinpcb_n", "List of active UDP sockets");

__private_extern__ void
udp_get_ports_used(uint32_t ifindex, int protocol, uint32_t flags,
    bitstr_t *bitfield)
{
        inpcb_get_ports_used(ifindex, protocol, flags, bitfield, &udbinfo);
}

__private_extern__ uint32_t
udp_count_opportunistic(unsigned int ifindex, u_int32_t flags)
{
        return (inpcb_count_opportunistic(ifindex, &udbinfo, flags));
}

__private_extern__ uint32_t
udp_find_anypcb_byaddr(struct ifaddr *ifa)
{
        return (inpcb_find_anypcb_byaddr(ifa, &udbinfo));
}

static int
udp_check_pktinfo(struct mbuf *control, struct ifnet **outif,
    struct in_addr *laddr)
{
        struct cmsghdr *cm = 0;
        struct in_pktinfo *pktinfo;
        struct ifnet *ifp;

        if (outif != NULL)
                *outif = NULL;

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

        if (control->m_len < CMSG_LEN(0))
                return (EINVAL);

        for (cm = M_FIRST_CMSGHDR(control); cm;
            cm = M_NXT_CMSGHDR(control, cm)) {
                if (cm->cmsg_len < sizeof (struct cmsghdr) ||
                    cm->cmsg_len > control->m_len)
                        return (EINVAL);

                if (cm->cmsg_level != IPPROTO_IP || cm->cmsg_type != IP_PKTINFO)
                        continue;

                if (cm->cmsg_len != CMSG_LEN(sizeof (struct in_pktinfo)))
                        return (EINVAL);

                pktinfo =  (struct in_pktinfo *)(void *)CMSG_DATA(cm);

                /* Check for a valid ifindex in pktinfo */
                ifnet_head_lock_shared();

                if (pktinfo->ipi_ifindex > if_index) {
                        ifnet_head_done();
                        return (ENXIO);
                }

                /*
                 * If ipi_ifindex is specified it takes precedence
                 * over ipi_spec_dst.
                 */
                if (pktinfo->ipi_ifindex) {
                        ifp = ifindex2ifnet[pktinfo->ipi_ifindex];
                        if (ifp == NULL) {
                                ifnet_head_done();
                                return (ENXIO);
                        }
                        if (outif != NULL) {
                                ifnet_reference(ifp);
                                *outif = ifp;
                        }
                        ifnet_head_done();
                        laddr->s_addr = INADDR_ANY;
                        break;
                }

                ifnet_head_done();

                /*
                 * Use the provided ipi_spec_dst address for temp
                 * source address.
                 */
                *laddr = pktinfo->ipi_spec_dst;
                break;
        }
        return (0);
}

static int
udp_output(struct inpcb *inp, struct mbuf *m, struct sockaddr *addr,
    struct mbuf *control, struct proc *p)
{
        struct udpiphdr *ui;
        int len = m->m_pkthdr.len;
        struct sockaddr_in *sin;
        struct in_addr origladdr, laddr, faddr, pi_laddr;
        u_short lport, fport;
        int error = 0, udp_dodisconnect = 0, pktinfo = 0;
        struct socket *so = inp->inp_socket;
        int soopts = 0;
        struct mbuf *inpopts;
        struct ip_moptions *mopts;
        struct route ro;
        struct ip_out_args ipoa =
            { IFSCOPE_NONE, { 0 }, IPOAF_SELECT_SRCIF, 0, 0, 0 };
        struct ifnet *outif = NULL;
        struct flowadv *adv = &ipoa.ipoa_flowadv;
        int sotc = SO_TC_UNSPEC;
        int netsvctype = _NET_SERVICE_TYPE_UNSPEC;
        struct ifnet *origoutifp = NULL;
        int flowadv = 0;

        /* Enable flow advisory only when connected */
        flowadv = (so->so_state & SS_ISCONNECTED) ? 1 : 0;
        pi_laddr.s_addr = INADDR_ANY;

        KERNEL_DEBUG(DBG_FNC_UDP_OUTPUT | DBG_FUNC_START, 0, 0, 0, 0, 0);

        lck_mtx_assert(&inp->inpcb_mtx, LCK_MTX_ASSERT_OWNED);
        if (control != NULL) {
                sotc = so_tc_from_control(control, &netsvctype);
                VERIFY(outif == NULL);
                error = udp_check_pktinfo(control, &outif, &pi_laddr);
                m_freem(control);
                control = NULL;
                if (error)
                        goto release;
                pktinfo++;
                if (outif != NULL)
                        ipoa.ipoa_boundif = outif->if_index;
        }
        if (sotc == SO_TC_UNSPEC) {
                sotc = so->so_traffic_class;
                netsvctype = so->so_netsvctype;
        }

        KERNEL_DEBUG(DBG_LAYER_OUT_BEG, inp->inp_fport, inp->inp_lport,
            inp->inp_laddr.s_addr, inp->inp_faddr.s_addr,
            (htons((u_short)len + sizeof (struct udphdr))));

        if (len + sizeof (struct udpiphdr) > IP_MAXPACKET) {
                error = EMSGSIZE;
                goto release;
        }

        if (flowadv && INP_WAIT_FOR_IF_FEEDBACK(inp)) {
                /*
                 * The socket is flow-controlled, drop the packets
                 * until the inp is not flow controlled
                 */
                error = ENOBUFS;
                goto release;
        }
        /*
         * If socket was bound to an ifindex, tell ip_output about it.
         * If the ancillary IP_PKTINFO option contains an interface index,
         * it takes precedence over the one specified by IP_BOUND_IF.
         */
        if (ipoa.ipoa_boundif == IFSCOPE_NONE &&
            (inp->inp_flags & INP_BOUND_IF)) {
                VERIFY(inp->inp_boundifp != NULL);
                ifnet_reference(inp->inp_boundifp);     /* for this routine */
                if (outif != NULL)
                        ifnet_release(outif);
                outif = inp->inp_boundifp;
                ipoa.ipoa_boundif = outif->if_index;
        }
        if (INP_NO_CELLULAR(inp))
                ipoa.ipoa_flags |=  IPOAF_NO_CELLULAR;
        if (INP_NO_EXPENSIVE(inp))
                ipoa.ipoa_flags |=  IPOAF_NO_EXPENSIVE;
        if (INP_AWDL_UNRESTRICTED(inp))
                ipoa.ipoa_flags |=  IPOAF_AWDL_UNRESTRICTED;
        ipoa.ipoa_sotc = sotc;
        ipoa.ipoa_netsvctype = netsvctype;
        soopts |= IP_OUTARGS;

        /*
         * If there was a routing change, discard cached route and check
         * that we have a valid source address.  Reacquire a new source
         * address if INADDR_ANY was specified.
         */
        if (ROUTE_UNUSABLE(&inp->inp_route)) {
                struct in_ifaddr *ia = NULL;

                ROUTE_RELEASE(&inp->inp_route);

                /* src address is gone? */
                if (inp->inp_laddr.s_addr != INADDR_ANY &&
                    (ia = ifa_foraddr(inp->inp_laddr.s_addr)) == NULL) {
                        if (!(inp->inp_flags & INP_INADDR_ANY) ||
                            (so->so_state & SS_ISCONNECTED)) {
                                /*
                                 * Rdar://5448998
                                 * If the source address is gone, return an
                                 * error if:
                                 * - the source was specified
                                 * - the socket was already connected
                                 */
                                soevent(so, (SO_FILT_HINT_LOCKED |
                                    SO_FILT_HINT_NOSRCADDR));
                                error = EADDRNOTAVAIL;
                                goto release;
                        } else {
                                /* new src will be set later */
                                inp->inp_laddr.s_addr = INADDR_ANY;
                                inp->inp_last_outifp = NULL;
                        }
                }
                if (ia != NULL)
                        IFA_REMREF(&ia->ia_ifa);
        }

        /*
         * IP_PKTINFO option check.  If a temporary scope or src address
         * is provided, use it for this packet only and make sure we forget
         * it after sending this datagram.
         */
        if (pi_laddr.s_addr != INADDR_ANY ||
            (ipoa.ipoa_boundif != IFSCOPE_NONE && pktinfo)) {
                /* temp src address for this datagram only */
                laddr = pi_laddr;
                origladdr.s_addr = INADDR_ANY;
                /* we don't want to keep the laddr or route */
                udp_dodisconnect = 1;
                /* remember we don't care about src addr */
                inp->inp_flags |= INP_INADDR_ANY;
        } else {
                origladdr = laddr = inp->inp_laddr;
        }

        origoutifp = inp->inp_last_outifp;
        faddr = inp->inp_faddr;
        lport = inp->inp_lport;
        fport = inp->inp_fport;

        if (addr) {
                sin = (struct sockaddr_in *)(void *)addr;
                if (faddr.s_addr != INADDR_ANY) {
                        error = EISCONN;
                        goto release;
                }
                if (lport == 0) {
                        /*
                         * In case we don't have a local port set, go through
                         * the full connect.  We don't have a local port yet
                         * (i.e., we can't be looked up), so it's not an issue
                         * if the input runs at the same time we do this.
                         */
                        /* if we have a source address specified, use that */
                        if (pi_laddr.s_addr != INADDR_ANY)
                                inp->inp_laddr = pi_laddr;
                        /*
                         * If a scope is specified, use it.  Scope from
                         * IP_PKTINFO takes precendence over the the scope
                         * set via INP_BOUND_IF.
                         */
                        error = in_pcbconnect(inp, addr, p, ipoa.ipoa_boundif,
                            &outif);
                        if (error)
                                goto release;

                        laddr = inp->inp_laddr;
                        lport = inp->inp_lport;
                        faddr = inp->inp_faddr;
                        fport = inp->inp_fport;
                        udp_dodisconnect = 1;

                        /* synch up in case in_pcbladdr() overrides */
                        if (outif != NULL && ipoa.ipoa_boundif != IFSCOPE_NONE)
                                ipoa.ipoa_boundif = outif->if_index;
                } else {
                        /*
                         * Fast path case
                         *
                         * We have a full address and a local port; use those
                         * info to build the packet without changing the pcb
                         * and interfering with the input path. See 3851370.
                         *
                         * Scope from IP_PKTINFO takes precendence over the
                         * the scope set via INP_BOUND_IF.
                         */
                        if (laddr.s_addr == INADDR_ANY) {
                                if ((error = in_pcbladdr(inp, addr, &laddr,
                                    ipoa.ipoa_boundif, &outif, 0)) != 0)
                                        goto release;
                                /*
                                 * from pcbconnect: remember we don't
                                 * care about src addr.
                                 */
                                inp->inp_flags |= INP_INADDR_ANY;

                                /* synch up in case in_pcbladdr() overrides */
                                if (outif != NULL &&
                                    ipoa.ipoa_boundif != IFSCOPE_NONE)
                                        ipoa.ipoa_boundif = outif->if_index;
                        }

                        faddr = sin->sin_addr;
                        fport = sin->sin_port;
                }
        } else {
                if (faddr.s_addr == INADDR_ANY) {
                        error = ENOTCONN;
                        goto release;
                }
        }

#if CONFIG_MACF_NET
        mac_mbuf_label_associate_inpcb(inp, m);
#endif /* CONFIG_MACF_NET */

        if (inp->inp_flowhash == 0)
                inp->inp_flowhash = inp_calc_flowhash(inp);

        /*
         * Calculate data length and get a mbuf
         * for UDP and IP headers.
         */
        M_PREPEND(m, sizeof (struct udpiphdr), M_DONTWAIT, 1);
        if (m == 0) {
                error = ENOBUFS;
                goto abort;
        }

        /*
         * 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));   /* XXX still needed? */
        ui->ui_pr = IPPROTO_UDP;
        ui->ui_src = laddr;
        ui->ui_dst = faddr;
        ui->ui_sport = lport;
        ui->ui_dport = fport;
        ui->ui_ulen = htons((u_short)len + sizeof (struct udphdr));

        /*
         * Set up checksum and output datagram.
         */
        if (udpcksum && !(inp->inp_flags & INP_UDP_NOCKSUM)) {
                ui->ui_sum = in_pseudo(ui->ui_src.s_addr, ui->ui_dst.s_addr,
                    htons((u_short)len + sizeof (struct udphdr) + IPPROTO_UDP));
                m->m_pkthdr.csum_flags = CSUM_UDP;
                m->m_pkthdr.csum_data = offsetof(struct udphdr, uh_sum);
        } else {
                ui->ui_sum = 0;
        }
        ((struct ip *)ui)->ip_len = sizeof (struct udpiphdr) + len;
        ((struct ip *)ui)->ip_ttl = inp->inp_ip_ttl;    /* XXX */
        ((struct ip *)ui)->ip_tos = inp->inp_ip_tos;    /* XXX */
        udpstat.udps_opackets++;

        KERNEL_DEBUG(DBG_LAYER_OUT_END, ui->ui_dport, ui->ui_sport,
            ui->ui_src.s_addr, ui->ui_dst.s_addr, ui->ui_ulen);

#if NECP
        {
                necp_kernel_policy_id policy_id;
                u_int32_t route_rule_id;

                /*
                 * We need a route to perform NECP route rule checks
                 */
                if (net_qos_policy_restricted != 0 &&
                    ROUTE_UNUSABLE(&inp->inp_route)) {
                        struct sockaddr_in to;
                        struct sockaddr_in from;

                        ROUTE_RELEASE(&inp->inp_route);

                        bzero(&from, sizeof(struct sockaddr_in));
                        from.sin_family = AF_INET;
                        from.sin_len = sizeof(struct sockaddr_in);
                        from.sin_addr = laddr;

                        bzero(&to, sizeof(struct sockaddr_in));
                        to.sin_family = AF_INET;
                        to.sin_len = sizeof(struct sockaddr_in);
                        to.sin_addr = faddr;

                        inp->inp_route.ro_dst.sa_family = AF_INET;
                        inp->inp_route.ro_dst.sa_len = sizeof(struct sockaddr_in);
                        ((struct sockaddr_in *)(void *)&inp->inp_route.ro_dst)->sin_addr =
                                faddr;

                        rtalloc_scoped(&inp->inp_route, ipoa.ipoa_boundif);

                        inp_update_necp_policy(inp, (struct sockaddr *)&from,
                            (struct sockaddr *)&to, ipoa.ipoa_boundif);
                        inp->inp_policyresult.results.qos_marking_gencount = 0;
                }

                if (!necp_socket_is_allowed_to_send_recv_v4(inp, lport, fport,
                    &laddr, &faddr, NULL, &policy_id, &route_rule_id)) {
                        error = EHOSTUNREACH;
                        goto abort;
                }

                necp_mark_packet_from_socket(m, inp, policy_id, route_rule_id);

                if (net_qos_policy_restricted != 0) {
                        necp_socket_update_qos_marking(inp,
                            inp->inp_route.ro_rt, NULL, route_rule_id);
                }
        }
#endif /* NECP */
        if ((so->so_flags1 & SOF1_QOSMARKING_ALLOWED))
                ipoa.ipoa_flags |= IPOAF_QOSMARKING_ALLOWED;

#if IPSEC
        if (inp->inp_sp != NULL && ipsec_setsocket(m, inp->inp_socket) != 0) {
                error = ENOBUFS;
                goto abort;
        }
#endif /* IPSEC */

        inpopts = inp->inp_options;
        soopts |= (inp->inp_socket->so_options & (SO_DONTROUTE | SO_BROADCAST));
        mopts = inp->inp_moptions;
        if (mopts != NULL) {
                IMO_LOCK(mopts);
                IMO_ADDREF_LOCKED(mopts);
                if (IN_MULTICAST(ntohl(ui->ui_dst.s_addr)) &&
                    mopts->imo_multicast_ifp != NULL) {
                        /* no reference needed */
                        inp->inp_last_outifp = mopts->imo_multicast_ifp;
                }
                IMO_UNLOCK(mopts);
        }

        /* Copy the cached route and take an extra reference */
        inp_route_copyout(inp, &ro);

        set_packet_service_class(m, so, sotc, 0);
        m->m_pkthdr.pkt_flowsrc = FLOWSRC_INPCB;
        m->m_pkthdr.pkt_flowid = inp->inp_flowhash;
        m->m_pkthdr.pkt_proto = IPPROTO_UDP;
        m->m_pkthdr.pkt_flags |= (PKTF_FLOW_ID | PKTF_FLOW_LOCALSRC);
        if (flowadv)
                m->m_pkthdr.pkt_flags |= PKTF_FLOW_ADV;

        if (ipoa.ipoa_boundif != IFSCOPE_NONE)
                ipoa.ipoa_flags |= IPOAF_BOUND_IF;

        if (laddr.s_addr != INADDR_ANY)
                ipoa.ipoa_flags |= IPOAF_BOUND_SRCADDR;

        inp->inp_sndinprog_cnt++;

        socket_unlock(so, 0);
        error = ip_output(m, inpopts, &ro, soopts, mopts, &ipoa);
        m = NULL;
        socket_lock(so, 0);
        if (mopts != NULL)
                IMO_REMREF(mopts);

        if (error == 0 && nstat_collect) {
                boolean_t cell, wifi, wired;

                if (ro.ro_rt != NULL) {
                        cell = IFNET_IS_CELLULAR(ro.ro_rt->rt_ifp);
                        wifi = (!cell && IFNET_IS_WIFI(ro.ro_rt->rt_ifp));
                        wired = (!wifi && IFNET_IS_WIRED(ro.ro_rt->rt_ifp));
                } else {
                        cell = wifi = wired = FALSE;
                }
                INP_ADD_STAT(inp, cell, wifi, wired, txpackets, 1);
                INP_ADD_STAT(inp, cell, wifi, wired, txbytes, len);
        }

        if (flowadv && (adv->code == FADV_FLOW_CONTROLLED ||
            adv->code == FADV_SUSPENDED)) {
                /*
                 * return a hint to the application that
                 * the packet has been dropped
                 */
                error = ENOBUFS;
                inp_set_fc_state(inp, adv->code);
        }

        VERIFY(inp->inp_sndinprog_cnt > 0);
        if ( --inp->inp_sndinprog_cnt == 0)
                inp->inp_flags &= ~(INP_FC_FEEDBACK);

        /* Synchronize PCB cached route */
        inp_route_copyin(inp, &ro);

abort:
        if (udp_dodisconnect) {
                /* Always discard the cached route for unconnected socket */
                ROUTE_RELEASE(&inp->inp_route);
                in_pcbdisconnect(inp);
                inp->inp_laddr = origladdr;     /* XXX rehash? */
                /* no reference needed */
                inp->inp_last_outifp = origoutifp;
        } else if (inp->inp_route.ro_rt != NULL) {
                struct rtentry *rt = inp->inp_route.ro_rt;
                struct ifnet *outifp;

                if (rt->rt_flags & (RTF_MULTICAST|RTF_BROADCAST))
                        rt = NULL;      /* unusable */
                /*
                 * Always discard if it is a multicast or broadcast route.
                 */
                if (rt == NULL)
                        ROUTE_RELEASE(&inp->inp_route);

                /*
                 * If the destination route is unicast, update outifp with
                 * that of the route interface used by IP.
                 */
                if (rt != NULL &&
                    (outifp = rt->rt_ifp) != inp->inp_last_outifp) {
                        inp->inp_last_outifp = outifp; /* no reference needed */

                        so->so_pktheadroom = P2ROUNDUP(
                            sizeof(struct udphdr) +
                            sizeof(struct ip) +
                            ifnet_hdrlen(outifp) +
                            ifnet_packetpreamblelen(outifp),
                            sizeof(u_int32_t));
                }
        } else {
                ROUTE_RELEASE(&inp->inp_route);
        }

        /*
         * If output interface was cellular/expensive, and this socket is
         * denied access to it, generate an event.
         */
        if (error != 0 && (ipoa.ipoa_retflags & IPOARF_IFDENIED) &&
            (INP_NO_CELLULAR(inp) || INP_NO_EXPENSIVE(inp)))
                soevent(so, (SO_FILT_HINT_LOCKED|SO_FILT_HINT_IFDENIED));

release:
        KERNEL_DEBUG(DBG_FNC_UDP_OUTPUT | DBG_FUNC_END, error, 0, 0, 0, 0);

        if (m != NULL)
                m_freem(m);

        if (outif != NULL)
                ifnet_release(outif);

        return (error);
}

u_int32_t       udp_sendspace = 9216;           /* really max datagram size */
/* 187 1K datagrams (approx 192 KB) */
u_int32_t       udp_recvspace = 187 * (1024 +
#if INET6
                    sizeof (struct sockaddr_in6)
#else /* !INET6 */
                    sizeof (struct sockaddr_in)
#endif /* !INET6 */
                );

/* Check that the values of udp send and recv space do not exceed sb_max */
static int
sysctl_udp_sospace(struct sysctl_oid *oidp, void *arg1, int arg2,
    struct sysctl_req *req)
{
#pragma unused(arg1, arg2)
        u_int32_t new_value = 0, *space_p = NULL;
        int changed = 0, error = 0;
        u_quad_t sb_effective_max = (sb_max/(MSIZE+MCLBYTES)) * MCLBYTES;

        switch (oidp->oid_number) {
        case UDPCTL_RECVSPACE:
                space_p = &udp_recvspace;
                break;
        case UDPCTL_MAXDGRAM:
                space_p = &udp_sendspace;
                break;
        default:
                return (EINVAL);
        }
        error = sysctl_io_number(req, *space_p, sizeof (u_int32_t),
            &new_value, &changed);
        if (changed) {
                if (new_value > 0 && new_value <= sb_effective_max)
                        *space_p = new_value;
                else
                        error = ERANGE;
        }
        return (error);
}

SYSCTL_PROC(_net_inet_udp, UDPCTL_RECVSPACE, recvspace,
        CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_LOCKED, &udp_recvspace, 0,
        &sysctl_udp_sospace, "IU", "Maximum incoming UDP datagram size");

SYSCTL_PROC(_net_inet_udp, UDPCTL_MAXDGRAM, maxdgram,
        CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_LOCKED, &udp_sendspace, 0,
        &sysctl_udp_sospace, "IU", "Maximum outgoing UDP datagram size");

static int
udp_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);
        in_pcbdetach(inp);
        return (0);
}

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

        inp = sotoinpcb(so);
        if (inp != NULL) {
                panic("%s so=%p inp=%p\n", __func__, so, inp);
                /* NOTREACHED */
        }
        error = in_pcballoc(so, &udbinfo, p);
        if (error != 0)
                return (error);
        error = soreserve(so, udp_sendspace, udp_recvspace);
        if (error != 0)
                return (error);
        inp = (struct inpcb *)so->so_pcb;
        inp->inp_vflag |= INP_IPV4;
        inp->inp_ip_ttl = ip_defttl;
        if (nstat_collect)
                nstat_udp_new_pcb(inp);
        return (0);
}

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

        if (nam->sa_family != 0 && nam->sa_family != AF_INET &&
            nam->sa_family != AF_INET6)
                return (EAFNOSUPPORT);

        inp = sotoinpcb(so);
        if (inp == NULL)
                return (EINVAL);
        error = in_pcbbind(inp, nam, p);
        return (error);
}

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

        inp = sotoinpcb(so);
        if (inp == NULL)
                return (EINVAL);
        if (inp->inp_faddr.s_addr != INADDR_ANY)
                return (EISCONN);

#if NECP
#if FLOW_DIVERT
        if (necp_socket_should_use_flow_divert(inp)) {
                uint32_t fd_ctl_unit =
                    necp_socket_get_flow_divert_control_unit(inp);
                if (fd_ctl_unit > 0) {
                        error = flow_divert_pcb_init(so, fd_ctl_unit);
                        if (error == 0) {
                                error = flow_divert_connect_out(so, nam, p);
                        }
                } else {
                        error = ENETDOWN;
                }
                return (error);
        }
#endif /* FLOW_DIVERT */
#endif /* NECP */

        error = in_pcbconnect(inp, nam, p, IFSCOPE_NONE, NULL);
        if (error == 0) {
                soisconnected(so);
                if (inp->inp_flowhash == 0)
                        inp->inp_flowhash = inp_calc_flowhash(inp);
        }
        return (error);
}

int
udp_connectx_common(struct socket *so, int af,
    struct sockaddr_list **src_sl, struct sockaddr_list **dst_sl,
    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)
{
#pragma unused(aid, flags, arg, arglen)
        struct sockaddr_entry *src_se = NULL, *dst_se = NULL;
        struct inpcb *inp = sotoinpcb(so);
        int error;
        user_ssize_t datalen = 0;

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

        VERIFY(dst_sl != NULL);

        /* select source (if specified) and destination addresses */
        error = in_selectaddrs(af, src_sl, &src_se, dst_sl, &dst_se);
        if (error != 0)
                return (error);

        VERIFY(*dst_sl != NULL && dst_se != NULL);
        VERIFY(src_se == NULL || *src_sl != NULL);
        VERIFY(dst_se->se_addr->sa_family == af);
        VERIFY(src_se == NULL || src_se->se_addr->sa_family == af);

#if NECP
        inp_update_necp_policy(inp, src_se ? src_se->se_addr : NULL,
            dst_se ? dst_se->se_addr : NULL, ifscope);
#endif /* NECP */

        /* bind socket to the specified interface, if requested */
        if (ifscope != IFSCOPE_NONE &&
            (error = inp_bindif(inp, ifscope, NULL)) != 0)
                return (error);

        /* if source address and/or port is specified, bind to it */
        if (src_se != NULL) {
                struct sockaddr *sa = src_se->se_addr;
                error = sobindlock(so, sa, 0);  /* already locked */
                if (error != 0)
                        return (error);
        }

        switch (af) {
        case AF_INET:
                error = udp_connect(so, dst_se->se_addr, p);
                break;
#if INET6
        case AF_INET6:
                error = udp6_connect(so, dst_se->se_addr, p);
                break;
#endif /* INET6 */
        default:
                VERIFY(0);
                /* NOTREACHED */
        }

        if (error != 0)
                return (error);

        /*
         * If there is data, copy it. DATA_IDEMPOTENT is ignored.
         * CONNECT_RESUME_ON_READ_WRITE is ignored.
         */
        if (uio != NULL) {
                socket_unlock(so, 0);

                VERIFY(bytes_written != NULL);

                datalen = uio_resid(uio);
                error = so->so_proto->pr_usrreqs->pru_sosend(so, NULL,
                    (uio_t)uio, NULL, NULL, 0);
                socket_lock(so, 0);

                /* If error returned is EMSGSIZE, for example, disconnect */
                if (error == 0 || error == EWOULDBLOCK)
                        *bytes_written = datalen - uio_resid(uio);
                else
                        (void) so->so_proto->pr_usrreqs->pru_disconnectx(so,
                            SAE_ASSOCID_ANY, SAE_CONNID_ANY);
                /*
                 * mask the EWOULDBLOCK error so that the caller
                 * knows that atleast the connect was successful.
                 */
                if (error == EWOULDBLOCK)
                        error = 0;
        }

        if (error == 0 && pcid != NULL)
                *pcid = 1;      /* there is only 1 connection for UDP */

        return (error);
}

static int
udp_connectx(struct socket *so, struct sockaddr_list **src_sl,
    struct sockaddr_list **dst_sl, 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_INET, src_sl, dst_sl,
            p, ifscope, aid, pcid, flags, arg, arglen, uio, bytes_written));
}

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

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

        /*
         * If this is a socket that does not want to wakeup the device
         * for it's traffic, the application might be waiting for
         * close to complete before going to sleep. Send a notification
         * for this kind of sockets
         */
        if (so->so_options & SO_NOWAKEFROMSLEEP)
                socket_post_kev_msg_closed(so);

        in_pcbdetach(inp);
        inp->inp_state = INPCB_STATE_DEAD;
        return (0);
}

static int
udp_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_faddr.s_addr == INADDR_ANY)
                return (ENOTCONN);

        in_pcbdisconnect(inp);

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

        inp->inp_laddr.s_addr = INADDR_ANY;
        so->so_state &= ~SS_ISCONNECTED;                /* XXX */
        inp->inp_last_outifp = NULL;
        return (0);
}

static int
udp_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 (udp_disconnect(so));
}

static int
udp_send(struct socket *so, int flags, struct mbuf *m,
    struct sockaddr *addr, struct mbuf *control, struct proc *p)
{
#ifndef FLOW_DIVERT
#pragma unused(flags)
#endif /* !(FLOW_DIVERT) */
        struct inpcb *inp;

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

#if NECP
#if FLOW_DIVERT
        if (necp_socket_should_use_flow_divert(inp)) {
                /* Implicit connect */
                return (flow_divert_implicit_data_out(so, flags, m, addr,
                    control, p));
        }
#endif /* FLOW_DIVERT */
#endif /* NECP */

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

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

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

int
udp_lock(struct socket *so, int refcount, void *debug)
{
        void *lr_saved;

        if (debug == NULL)
                lr_saved = __builtin_return_address(0);
        else
                lr_saved = debug;

        if (so->so_pcb != NULL) {
                lck_mtx_assert(&((struct inpcb *)so->so_pcb)->inpcb_mtx,
                    LCK_MTX_ASSERT_NOTOWNED);
                lck_mtx_lock(&((struct inpcb *)so->so_pcb)->inpcb_mtx);
        } else {
                panic("%s: so=%p NO PCB! lr=%p lrh= %s\n", __func__,
                    so, lr_saved, solockhistory_nr(so));
                /* NOTREACHED */
        }
        if (refcount)
                so->so_usecount++;

        so->lock_lr[so->next_lock_lr] = lr_saved;
        so->next_lock_lr = (so->next_lock_lr+1) % SO_LCKDBG_MAX;
        return (0);
}

int
udp_unlock(struct socket *so, int refcount, void *debug)
{
        void *lr_saved;

        if (debug == NULL)
                lr_saved = __builtin_return_address(0);
        else
                lr_saved = debug;

        if (refcount)
                so->so_usecount--;

        if (so->so_pcb == NULL) {
                panic("%s: so=%p NO PCB! lr=%p lrh= %s\n", __func__,
                    so, lr_saved, solockhistory_nr(so));
                /* NOTREACHED */
        } else {
                lck_mtx_assert(&((struct inpcb *)so->so_pcb)->inpcb_mtx,
                    LCK_MTX_ASSERT_OWNED);
                so->unlock_lr[so->next_unlock_lr] = lr_saved;
                so->next_unlock_lr = (so->next_unlock_lr+1) % SO_LCKDBG_MAX;
                lck_mtx_unlock(&((struct inpcb *)so->so_pcb)->inpcb_mtx);
        }
        return (0);
}

lck_mtx_t *
udp_getlock(struct socket *so, int locktype)
{
#pragma unused(locktype)
        struct inpcb *inp = sotoinpcb(so);

        if (so->so_pcb == NULL) {
                panic("%s: so=%p NULL so_pcb lrh= %s\n", __func__,
                    so, solockhistory_nr(so));
                /* NOTREACHED */
        }
        return (&inp->inpcb_mtx);
}

/*
 * UDP garbage collector callback (inpcb_timer_func_t).
 *
 * Returns > 0 to keep timer active.
 */
static void
udp_gc(struct inpcbinfo *ipi)
{
        struct inpcb *inp, *inpnxt;
        struct socket *so;

        if (lck_rw_try_lock_exclusive(ipi->ipi_lock) == FALSE) {
                if (udp_gc_done == TRUE) {
                        udp_gc_done = FALSE;
                        /* couldn't get the lock, must lock next time */
                        atomic_add_32(&ipi->ipi_gc_req.intimer_fast, 1);
                        return;
                }
                lck_rw_lock_exclusive(ipi->ipi_lock);
        }

        udp_gc_done = TRUE;

        for (inp = udb.lh_first; inp != NULL; inp = inpnxt) {
                inpnxt = inp->inp_list.le_next;

                /*
                 * Skip unless it's STOPUSING; garbage collector will
                 * be triggered by in_pcb_checkstate() upon setting
                 * wantcnt to that value.  If the PCB is already dead,
                 * keep gc active to anticipate wantcnt changing.
                 */
                if (inp->inp_wantcnt != WNT_STOPUSING)
                        continue;

                /*
                 * Skip if busy, no hurry for cleanup.  Keep gc active
                 * and try the lock again during next round.
                 */
                if (!lck_mtx_try_lock(&inp->inpcb_mtx)) {
                        atomic_add_32(&ipi->ipi_gc_req.intimer_fast, 1);
                        continue;
                }

                /*
                 * Keep gc active unless usecount is 0.
                 */
                so = inp->inp_socket;
                if (so->so_usecount == 0) {
                        if (inp->inp_state != INPCB_STATE_DEAD) {
#if INET6
                                if (SOCK_CHECK_DOM(so, PF_INET6))
                                        in6_pcbdetach(inp);
                                else
#endif /* INET6 */
                                        in_pcbdetach(inp);
                        }
                        in_pcbdispose(inp);
                } else {
                        lck_mtx_unlock(&inp->inpcb_mtx);
                        atomic_add_32(&ipi->ipi_gc_req.intimer_fast, 1);
                }
        }
        lck_rw_done(ipi->ipi_lock);
}

static int
udp_getstat SYSCTL_HANDLER_ARGS
{
#pragma unused(oidp, arg1, arg2)
        if (req->oldptr == USER_ADDR_NULL)
                req->oldlen = (size_t)sizeof (struct udpstat);

        return (SYSCTL_OUT(req, &udpstat, MIN(sizeof (udpstat), req->oldlen)));
}

void
udp_in_cksum_stats(u_int32_t len)
{
        udpstat.udps_rcv_swcsum++;
        udpstat.udps_rcv_swcsum_bytes += len;
}

void
udp_out_cksum_stats(u_int32_t len)
{
        udpstat.udps_snd_swcsum++;
        udpstat.udps_snd_swcsum_bytes += len;
}

#if INET6
void
udp_in6_cksum_stats(u_int32_t len)
{
        udpstat.udps_rcv6_swcsum++;
        udpstat.udps_rcv6_swcsum_bytes += len;
}

void
udp_out6_cksum_stats(u_int32_t len)
{
        udpstat.udps_snd6_swcsum++;
        udpstat.udps_snd6_swcsum_bytes += len;
}
#endif /* INET6 */

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

        if (uh->uh_sum == 0) {
                udpstat.udps_nosum++;
                return (0);
        }

        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 {
                        uint16_t sum = m->m_pkthdr.csum_rx_val;
                        uint16_t start = m->m_pkthdr.csum_rx_start;

                        /*
                         * Perform 1's complement adjustment of octets
                         * that got included/excluded in the hardware-
                         * calculated checksum value.  Ignore cases
                         * where the value includes or excludes the
                         * IP header span, as the sum for those octets
                         * would already be 0xffff and thus no-op.
                         */
                        if ((m->m_pkthdr.csum_flags & CSUM_PARTIAL) &&
                            start != 0 && (off - start) != off) {
#if BYTE_ORDER != BIG_ENDIAN
                                if (start < off) {
                                        HTONS(ip->ip_len);
                                        HTONS(ip->ip_off);
                                }
#endif /* BYTE_ORDER != BIG_ENDIAN */
                                /* callee folds in sum */
                                sum = m_adj_sum16(m, start, off, sum);
#if BYTE_ORDER != BIG_ENDIAN
                                if (start < off) {
                                        NTOHS(ip->ip_off);
                                        NTOHS(ip->ip_len);
                                }
#endif /* BYTE_ORDER != BIG_ENDIAN */
                        }

                        /* callee folds in sum */
                        uh->uh_sum = in_pseudo(ip->ip_src.s_addr,
                            ip->ip_dst.s_addr, sum + htonl(ulen + IPPROTO_UDP));
                }
                uh->uh_sum ^= 0xffff;
        } else {
                uint16_t ip_sum;
                char b[9];

                bcopy(ipov->ih_x1, b, sizeof (ipov->ih_x1));
                bzero(ipov->ih_x1, sizeof (ipov->ih_x1));
                ip_sum = ipov->ih_len;
                ipov->ih_len = uh->uh_ulen;
                uh->uh_sum = in_cksum(m, ulen + sizeof (struct ip));
                bcopy(b, ipov->ih_x1, sizeof (ipov->ih_x1));
                ipov->ih_len = ip_sum;

                udp_in_cksum_stats(ulen);
        }

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

        return (0);
}

void
udp_fill_keepalive_offload_frames(ifnet_t ifp,
    struct ifnet_keepalive_offload_frame *frames_array,
    u_int32_t frames_array_count, size_t frame_data_offset,
    u_int32_t *used_frames_count)
{
        struct inpcb *inp;
        inp_gen_t gencnt;
        u_int32_t frame_index = *used_frames_count;

        if (ifp == NULL || frames_array == NULL ||
            frames_array_count == 0 ||
            frame_index >= frames_array_count ||
            frame_data_offset >= IFNET_KEEPALIVE_OFFLOAD_FRAME_DATA_SIZE)
                return;

        lck_rw_lock_shared(udbinfo.ipi_lock);
        gencnt = udbinfo.ipi_gencnt;
        LIST_FOREACH(inp, udbinfo.ipi_listhead, inp_list) {
                struct socket *so;
                u_int8_t *data;
                struct ifnet_keepalive_offload_frame *frame;
                struct mbuf *m = NULL;

                if (frame_index >= frames_array_count)
                        break;

                if (inp->inp_gencnt > gencnt ||
                    inp->inp_state == INPCB_STATE_DEAD)
                        continue;

                if ((so = inp->inp_socket) == NULL ||
                    (so->so_state & SS_DEFUNCT))
                        continue;
                /*
                 * check for keepalive offload flag without socket
                 * lock to avoid a deadlock
                 */
                if (!(inp->inp_flags2 & INP2_KEEPALIVE_OFFLOAD)) {
                        continue;
                }

                udp_lock(so, 1, 0);
                if (!(inp->inp_vflag & (INP_IPV4 | INP_IPV6))) {
                        udp_unlock(so, 1, 0);
                        continue;
                }
                if ((inp->inp_vflag & INP_IPV4) &&
                    (inp->inp_laddr.s_addr == INADDR_ANY ||
                    inp->inp_faddr.s_addr == INADDR_ANY)) {
                        udp_unlock(so, 1, 0);
                        continue;
                }
                if ((inp->inp_vflag & INP_IPV6) &&
                    (IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_laddr) ||
                    IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_faddr))) {
                        udp_unlock(so, 1, 0);
                        continue;
                }
                if (inp->inp_lport == 0 || inp->inp_fport == 0) {
                        udp_unlock(so, 1, 0);
                        continue;
                }
                if (inp->inp_last_outifp == NULL ||
                    inp->inp_last_outifp->if_index != ifp->if_index) {
                        udp_unlock(so, 1, 0);
                        continue;
                }
                if ((inp->inp_vflag & INP_IPV4)) {
                        if ((frame_data_offset + sizeof(struct udpiphdr) +
                            inp->inp_keepalive_datalen) >
                            IFNET_KEEPALIVE_OFFLOAD_FRAME_DATA_SIZE) {
                                udp_unlock(so, 1, 0);
                                continue;
                        }
                        if ((sizeof(struct udpiphdr) +
                            inp->inp_keepalive_datalen) > _MHLEN) {
                                udp_unlock(so, 1, 0);
                                continue;
                        }
                } else {
                        if ((frame_data_offset + sizeof(struct ip6_hdr) +
                            sizeof(struct udphdr) +
                            inp->inp_keepalive_datalen) >
                            IFNET_KEEPALIVE_OFFLOAD_FRAME_DATA_SIZE) {
                                udp_unlock(so, 1, 0);
                                continue;
                        }
                        if ((sizeof(struct ip6_hdr) + sizeof(struct udphdr) +
                            inp->inp_keepalive_datalen) > _MHLEN) {
                                udp_unlock(so, 1, 0);
                                continue;
                        }
                }
                MGETHDR(m, M_WAIT, MT_HEADER);
                if (m == NULL) {
                        udp_unlock(so, 1, 0);
                        continue;
                }
                /*
                 * This inp has all the information that is needed to
                 * generate an offload frame.
                 */
                if (inp->inp_vflag & INP_IPV4) {
                        struct ip *ip;
                        struct udphdr *udp;

                        frame = &frames_array[frame_index];
                        frame->length = frame_data_offset +
                            sizeof(struct udpiphdr) +
                            inp->inp_keepalive_datalen;
                        frame->ether_type =
                            IFNET_KEEPALIVE_OFFLOAD_FRAME_ETHERTYPE_IPV4;
                        frame->interval = inp->inp_keepalive_interval;
                        switch (inp->inp_keepalive_type) {
                        case UDP_KEEPALIVE_OFFLOAD_TYPE_AIRPLAY:
                                frame->type =
                                    IFNET_KEEPALIVE_OFFLOAD_FRAME_AIRPLAY;
                                break;
                        default:
                                break;
                        }
                        data = mtod(m, u_int8_t *);
                        bzero(data, sizeof(struct udpiphdr));
                        ip = (__typeof__(ip))(void *)data;
                        udp = (__typeof__(udp))(void *) (data +
                            sizeof(struct ip));
                        m->m_len = sizeof(struct udpiphdr);
                        data = data + sizeof(struct udpiphdr);
                        if (inp->inp_keepalive_datalen > 0 &&
                            inp->inp_keepalive_data != NULL) {
                                bcopy(inp->inp_keepalive_data, data,
                                    inp->inp_keepalive_datalen);
                                m->m_len += inp->inp_keepalive_datalen;
                        }
                        m->m_pkthdr.len = m->m_len;

                        ip->ip_v = IPVERSION;
                        ip->ip_hl = (sizeof(struct ip) >> 2);
                        ip->ip_p = IPPROTO_UDP;
                        ip->ip_len = htons(sizeof(struct udpiphdr) +
                            (u_short)inp->inp_keepalive_datalen);
                        ip->ip_ttl = inp->inp_ip_ttl;
                        ip->ip_tos = inp->inp_ip_tos;
                        ip->ip_src = inp->inp_laddr;
                        ip->ip_dst = inp->inp_faddr;
                        ip->ip_sum = in_cksum_hdr_opt(ip);

                        udp->uh_sport = inp->inp_lport;
                        udp->uh_dport = inp->inp_fport;
                        udp->uh_ulen = htons(sizeof(struct udphdr) +
                            (u_short)inp->inp_keepalive_datalen);

                        if (!(inp->inp_flags & INP_UDP_NOCKSUM)) {
                                udp->uh_sum = in_pseudo(ip->ip_src.s_addr,
                                    ip->ip_dst.s_addr,
                                    htons(sizeof(struct udphdr) +
                                    (u_short)inp->inp_keepalive_datalen +
                                    IPPROTO_UDP));
                                m->m_pkthdr.csum_flags = CSUM_UDP;
                                m->m_pkthdr.csum_data = offsetof(struct udphdr,
                                    uh_sum);
                        }
                        m->m_pkthdr.pkt_proto = IPPROTO_UDP;
                        in_delayed_cksum(m);
                        bcopy(m->m_data, frame->data + frame_data_offset,
                            m->m_len);
                } else {
                        struct ip6_hdr *ip6;
                        struct udphdr *udp6;

                        VERIFY(inp->inp_vflag & INP_IPV6);
                        frame = &frames_array[frame_index];
                        frame->length = frame_data_offset +
                            sizeof(struct ip6_hdr) +
                            sizeof(struct udphdr) +
                            inp->inp_keepalive_datalen;
                        frame->ether_type =
                            IFNET_KEEPALIVE_OFFLOAD_FRAME_ETHERTYPE_IPV6;
                        frame->interval = inp->inp_keepalive_interval;
                        switch (inp->inp_keepalive_type) {
                        case UDP_KEEPALIVE_OFFLOAD_TYPE_AIRPLAY:
                                frame->type =
                                    IFNET_KEEPALIVE_OFFLOAD_FRAME_AIRPLAY;
                                break;
                        default:
                                break;
                        }
                        data = mtod(m, u_int8_t *);
                        bzero(data, sizeof(struct ip6_hdr) + sizeof(struct udphdr));
                        ip6 = (__typeof__(ip6))(void *)data;
                        udp6 = (__typeof__(udp6))(void *)(data +
                            sizeof(struct ip6_hdr));
                        m->m_len = sizeof(struct ip6_hdr) +
                            sizeof(struct udphdr);
                        data = data + (sizeof(struct ip6_hdr) +
                            sizeof(struct udphdr));
                        if (inp->inp_keepalive_datalen > 0 &&
                            inp->inp_keepalive_data != NULL) {
                                bcopy(inp->inp_keepalive_data, data,
                                    inp->inp_keepalive_datalen);
                                m->m_len += inp->inp_keepalive_datalen;
                        }
                        m->m_pkthdr.len = m->m_len;
                        ip6->ip6_flow = inp->inp_flow & IPV6_FLOWINFO_MASK;
                        ip6->ip6_vfc &= ~IPV6_VERSION_MASK;
                        ip6->ip6_vfc |= IPV6_VERSION;
                        ip6->ip6_nxt = IPPROTO_UDP;
                        ip6->ip6_hlim = ip6_defhlim;
                        ip6->ip6_plen = htons(sizeof(struct udphdr) +
                            (u_short)inp->inp_keepalive_datalen);
                        ip6->ip6_src = inp->in6p_laddr;
                        if (IN6_IS_SCOPE_EMBED(&ip6->ip6_src))
                                ip6->ip6_src.s6_addr16[1] = 0;

                        ip6->ip6_dst = inp->in6p_faddr;
                        if (IN6_IS_SCOPE_EMBED(&ip6->ip6_dst))
                                ip6->ip6_dst.s6_addr16[1] = 0;

                        udp6->uh_sport = inp->in6p_lport;
                        udp6->uh_dport = inp->in6p_fport;
                        udp6->uh_ulen = htons(sizeof(struct udphdr) +
                            (u_short)inp->inp_keepalive_datalen);
                        if (!(inp->inp_flags & INP_UDP_NOCKSUM)) {
                                udp6->uh_sum = in6_pseudo(&ip6->ip6_src,
                                    &ip6->ip6_dst,
                                    htonl(sizeof(struct udphdr) +
                                    (u_short)inp->inp_keepalive_datalen +
                                    IPPROTO_UDP));
                                m->m_pkthdr.csum_flags = CSUM_UDPIPV6;
                                m->m_pkthdr.csum_data = offsetof(struct udphdr,
                                    uh_sum);
                        }
                        m->m_pkthdr.pkt_proto = IPPROTO_UDP;
                        in6_delayed_cksum(m);
                        bcopy(m->m_data, frame->data + frame_data_offset,
                            m->m_len);
                }
                if (m != NULL) {
                        m_freem(m);
                        m = NULL;
                }
                frame_index++;
                udp_unlock(so, 1, 0);
        }
        lck_rw_done(udbinfo.ipi_lock);
        *used_frames_count = frame_index;
}