/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995
 *      The Regents of the University of California.
 * Copyright (c) 2008 Robert N. M. Watson
 * Copyright (c) 2010-2011 Juniper Networks, Inc.
 * Copyright (c) 2014 Kevin Lo
 * All rights reserved.
 *
 * Portions of this software were developed by Robert N. M. Watson under
 * contract to Juniper Networks, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include "opt_inet.h"
#include "opt_inet6.h"
#include "opt_ipsec.h"
#include "opt_rss.h"

#include <sys/param.h>
#include <sys/domain.h>
#include <sys/eventhandler.h>
#include <sys/jail.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/protosw.h>
#include <sys/sdt.h>
#include <sys/signalvar.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/sx.h>
#include <sys/sysctl.h>
#include <sys/syslog.h>
#include <sys/systm.h>

#include <vm/uma.h>

#include <net/if.h>
#include <net/if_var.h>
#include <net/route.h>
#include <net/route/nhop.h>
#include <net/rss_config.h>

#include <netinet/in.h>
#include <netinet/in_kdtrace.h>
#include <netinet/in_fib.h>
#include <netinet/in_pcb.h>
#include <netinet/in_systm.h>
#include <netinet/in_var.h>
#include <netinet/ip.h>
#ifdef INET6
#include <netinet/ip6.h>
#endif
#include <netinet/ip_icmp.h>
#include <netinet/icmp_var.h>
#include <netinet/ip_var.h>
#include <netinet/ip_options.h>
#ifdef INET6
#include <netinet6/ip6_var.h>
#endif
#include <netinet/udp.h>
#include <netinet/udp_var.h>
#include <netinet/udplite.h>
#include <netinet/in_rss.h>

#include <netipsec/ipsec_support.h>

#include <machine/in_cksum.h>

#include <security/mac/mac_framework.h>

/*
 * UDP and UDP-Lite protocols implementation.
 * Per RFC 768, August, 1980.
 * Per RFC 3828, July, 2004.
 */

VNET_DEFINE(int, udp_bind_all_fibs) = 1;
SYSCTL_INT(_net_inet_udp, OID_AUTO, bind_all_fibs, CTLFLAG_VNET | CTLFLAG_RDTUN,
    &VNET_NAME(udp_bind_all_fibs), 0,
    "Bound sockets receive traffic from all FIBs");

/*
 * BSD 4.2 defaulted the udp checksum to be off.  Turning off udp checksums
 * removes the only data integrity mechanism for packets and malformed
 * packets that would otherwise be discarded due to bad checksums, and may
 * cause problems (especially for NFS data blocks).
 */
VNET_DEFINE(int, udp_cksum) = 1;
SYSCTL_INT(_net_inet_udp, UDPCTL_CHECKSUM, checksum, CTLFLAG_VNET | CTLFLAG_RW,
    &VNET_NAME(udp_cksum), 0, "compute udp checksum");

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

VNET_DEFINE(int, udp_blackhole) = 0;
SYSCTL_INT(_net_inet_udp, OID_AUTO, blackhole, CTLFLAG_VNET | CTLFLAG_RW,
    &VNET_NAME(udp_blackhole), 0,
    "Do not send port unreachables for refused connects");
VNET_DEFINE(bool, udp_blackhole_local) = false;
SYSCTL_BOOL(_net_inet_udp, OID_AUTO, blackhole_local, CTLFLAG_VNET |
    CTLFLAG_RW, &VNET_NAME(udp_blackhole_local), false,
    "Enforce net.inet.udp.blackhole for locally originated packets");

u_long  udp_sendspace = 9216;           /* really max datagram size */
SYSCTL_ULONG(_net_inet_udp, UDPCTL_MAXDGRAM, maxdgram, CTLFLAG_RW,
    &udp_sendspace, 0, "Maximum outgoing UDP datagram size");

u_long  udp_recvspace = 40 * (1024 +
#ifdef INET6
                                      sizeof(struct sockaddr_in6)
#else
                                      sizeof(struct sockaddr_in)
#endif
                                      );        /* 40 1K datagrams */

SYSCTL_ULONG(_net_inet_udp, UDPCTL_RECVSPACE, recvspace, CTLFLAG_RW,
    &udp_recvspace, 0, "Maximum space for incoming UDP datagrams");

VNET_DEFINE(struct inpcbinfo, udbinfo);
VNET_DEFINE(struct inpcbinfo, ulitecbinfo);

#ifndef UDBHASHSIZE
#define UDBHASHSIZE     128
#endif

VNET_PCPUSTAT_DEFINE(struct udpstat, udpstat);          /* from udp_var.h */
VNET_PCPUSTAT_SYSINIT(udpstat);
SYSCTL_VNET_PCPUSTAT(_net_inet_udp, UDPCTL_STATS, stats, struct udpstat,
    udpstat, "UDP statistics (struct udpstat, netinet/udp_var.h)");

#ifdef VIMAGE
VNET_PCPUSTAT_SYSUNINIT(udpstat);
#endif /* VIMAGE */
#ifdef INET
static void     udp_detach(struct socket *so);
#endif

INPCBSTORAGE_DEFINE(udpcbstor, udpcb, "udpinp", "udp_inpcb", "udp", "udphash");
INPCBSTORAGE_DEFINE(udplitecbstor, udpcb, "udpliteinp", "udplite_inpcb",
    "udplite", "udplitehash");

static void
udp_vnet_init(void *arg __unused)
{

        /*
         * For now default to 2-tuple UDP hashing - until the fragment
         * reassembly code can also update the flowid.
         *
         * Once we can calculate the flowid that way and re-establish
         * a 4-tuple, flip this to 4-tuple.
         */
        in_pcbinfo_init(&V_udbinfo, &udpcbstor, UDBHASHSIZE, UDBHASHSIZE);
        /* Additional pcbinfo for UDP-Lite */
        in_pcbinfo_init(&V_ulitecbinfo, &udplitecbstor, UDBHASHSIZE,
            UDBHASHSIZE);
}
VNET_SYSINIT(udp_vnet_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_FOURTH,
    udp_vnet_init, NULL);

/*
 * Kernel module interface for updating udpstat.  The argument is an index
 * into udpstat treated as an array of u_long.  While this encodes the
 * general layout of udpstat into the caller, it doesn't encode its location,
 * so that future changes to add, for example, per-CPU stats support won't
 * cause binary compatibility problems for kernel modules.
 */
void
kmod_udpstat_inc(int statnum)
{

        counter_u64_add(VNET(udpstat)[statnum], 1);
}

#ifdef VIMAGE
static void
udp_destroy(void *unused __unused)
{

        in_pcbinfo_destroy(&V_udbinfo);
        in_pcbinfo_destroy(&V_ulitecbinfo);
}
VNET_SYSUNINIT(udp, SI_SUB_PROTO_DOMAIN, SI_ORDER_FOURTH, udp_destroy, NULL);
#endif

#ifdef INET
/*
 * Subroutine of udp_input(), which appends the provided mbuf chain to the
 * passed pcb/socket.  The caller must provide a sockaddr_in via udp_in that
 * contains the source address.  If the socket ends up being an IPv6 socket,
 * udp_append() will convert to a sockaddr_in6 before passing the address
 * into the socket code.
 *
 * In the normal case udp_append() will return 'false', indicating that you
 * must unlock the inpcb.  However if a tunneling protocol is in place we
 * increment the inpcb refcnt and unlock the inpcb, on return from the tunneling
 * protocol we then decrement the reference count.  If in_pcbrele_rlocked()
 * returns 'true', indicating the inpcb is gone, we return that to the caller
 * to tell them *not* to unlock the inpcb.  In the case of multicast this will
 * cause the distribution to stop (though most tunneling protocols known
 * currently do *not* use multicast).
 *
 * The mbuf is always consumed.
 */
static bool
udp_append(struct inpcb *inp, struct ip *ip, struct mbuf *n, int off,
    struct sockaddr_in *udp_in)
{
        struct sockaddr *append_sa;
        struct socket *so;
        struct mbuf *tmpopts, *opts = NULL;
#ifdef INET6
        struct sockaddr_in6 udp_in6;
#endif
        struct udpcb *up;

        INP_LOCK_ASSERT(inp);

        /*
         * Engage the tunneling protocol.
         */
        up = intoudpcb(inp);
        if (up->u_tun_func != NULL) {
                bool filtered;

                in_pcbref(inp);
                INP_RUNLOCK(inp);
                filtered = (*up->u_tun_func)(n, off, inp,
                    (struct sockaddr *)&udp_in[0], up->u_tun_ctx);
                INP_RLOCK(inp);
                if (in_pcbrele_rlocked(inp)) {
                        if (!filtered)
                                m_freem(n);
                        return (true);
                }
                if (filtered)
                        return (false);
        }

        off += sizeof(struct udphdr);

#if defined(IPSEC) || defined(IPSEC_SUPPORT)
        /* Check AH/ESP integrity. */
        if (IPSEC_ENABLED(ipv4) &&
            IPSEC_CHECK_POLICY(ipv4, n, inp) != 0) {
                m_freem(n);
                return (false);
        }
        if (up->u_flags & UF_ESPINUDP) {/* IPSec UDP encaps. */
                if (IPSEC_ENABLED(ipv4) &&
                    UDPENCAP_INPUT(ipv4, n, off, AF_INET) != 0)
                        return (false);
        }
#endif /* IPSEC */
#ifdef MAC
        if (mac_inpcb_check_deliver(inp, n) != 0) {
                m_freem(n);
                return (false);
        }
#endif /* MAC */
        if (inp->inp_flags & INP_CONTROLOPTS ||
            inp->inp_socket->so_options & (SO_TIMESTAMP | SO_BINTIME)) {
#ifdef INET6
                if (inp->inp_vflag & INP_IPV6)
                        (void)ip6_savecontrol_v4(inp, n, &opts, NULL);
                else
#endif /* INET6 */
                        ip_savecontrol(inp, &opts, ip, n);
        }
        if ((inp->inp_vflag & INP_IPV4) && (inp->inp_flags2 & INP_ORIGDSTADDR)) {
                tmpopts = sbcreatecontrol(&udp_in[1],
                    sizeof(struct sockaddr_in), IP_ORIGDSTADDR, IPPROTO_IP,
                    M_NOWAIT);
                if (tmpopts) {
                        if (opts) {
                                tmpopts->m_next = opts;
                                opts = tmpopts;
                        } else
                                opts = tmpopts;
                }
        }
#ifdef INET6
        if (inp->inp_vflag & INP_IPV6) {
                bzero(&udp_in6, sizeof(udp_in6));
                udp_in6.sin6_len = sizeof(udp_in6);
                udp_in6.sin6_family = AF_INET6;
                in6_sin_2_v4mapsin6(&udp_in[0], &udp_in6);
                append_sa = (struct sockaddr *)&udp_in6;
        } else
#endif /* INET6 */
                append_sa = (struct sockaddr *)&udp_in[0];
        m_adj(n, off);

        so = inp->inp_socket;
        SOCKBUF_LOCK(&so->so_rcv);
        if (sbappendaddr_locked(&so->so_rcv, append_sa, n, opts) == 0) {
                soroverflow_locked(so);
                m_freem(n);
                if (opts)
                        m_freem(opts);
                UDPSTAT_INC(udps_fullsock);
        } else
                sorwakeup_locked(so);
        return (false);
}

static bool
udp_multi_match(const struct inpcb *inp, void *v)
{
        struct ip *ip = v;
        struct udphdr *uh = (struct udphdr *)(ip + 1);

        if (inp->inp_lport != uh->uh_dport)
                return (false);
#ifdef INET6
        if ((inp->inp_vflag & INP_IPV4) == 0)
                return (false);
#endif
        if (inp->inp_laddr.s_addr != INADDR_ANY &&
            inp->inp_laddr.s_addr != ip->ip_dst.s_addr)
                return (false);
        if (inp->inp_faddr.s_addr != INADDR_ANY &&
            inp->inp_faddr.s_addr != ip->ip_src.s_addr)
                return (false);
        if (inp->inp_fport != 0 &&
            inp->inp_fport != uh->uh_sport)
                return (false);

        return (true);
}

static int
udp_multi_input(struct mbuf *m, int proto, struct sockaddr_in *udp_in)
{
        struct ip *ip = mtod(m, struct ip *);
        struct inpcb_iterator inpi = INP_ITERATOR(udp_get_inpcbinfo(proto),
            INPLOOKUP_RLOCKPCB, udp_multi_match, ip);
#ifdef KDTRACE_HOOKS
        struct udphdr *uh = (struct udphdr *)(ip + 1);
#endif
        struct inpcb *inp;
        struct mbuf *n;
        int appends = 0, fib;

        MPASS(ip->ip_hl == sizeof(struct ip) >> 2);

        fib = M_GETFIB(m);

        while ((inp = inp_next(&inpi)) != NULL) {
                /*
                 * XXXRW: Because we weren't holding either the inpcb
                 * or the hash lock when we checked for a match
                 * before, we should probably recheck now that the
                 * inpcb lock is held.
                 */

                if (V_udp_bind_all_fibs == 0 && fib != inp->inp_inc.inc_fibnum)
                        /*
                         * Sockets bound to a specific FIB can only receive
                         * packets from that FIB.
                         */
                        continue;

                /*
                 * Handle socket delivery policy for any-source
                 * and source-specific multicast. [RFC3678]
                 */
                if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
                        struct ip_moptions      *imo;
                        struct sockaddr_in       group;
                        int                      blocked;

                        imo = inp->inp_moptions;
                        if (imo == NULL)
                                continue;
                        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, m->m_pkthdr.rcvif,
                                (struct sockaddr *)&group,
                                (struct sockaddr *)&udp_in[0]);
                        if (blocked != MCAST_PASS) {
                                if (blocked == MCAST_NOTGMEMBER)
                                        IPSTAT_INC(ips_notmember);
                                if (blocked == MCAST_NOTSMEMBER ||
                                    blocked == MCAST_MUTED)
                                        UDPSTAT_INC(udps_filtermcast);
                                continue;
                        }
                }
                if ((n = m_copym(m, 0, M_COPYALL, M_NOWAIT)) != NULL) {
                        if (proto == IPPROTO_UDPLITE)
                                UDPLITE_PROBE(receive, NULL, inp, ip, inp, uh);
                        else
                                UDP_PROBE(receive, NULL, inp, ip, inp, uh);
                        if (udp_append(inp, ip, n, sizeof(struct ip), udp_in)) {
                                break;
                        } else
                                appends++;
                }
                /*
                 * Don't look for additional matches if this one does
                 * not have either the SO_REUSEPORT or SO_REUSEADDR
                 * socket options set.  This heuristic avoids
                 * searching through all pcbs in the common case of a
                 * non-shared port.  It assumes that an application
                 * will never clear these options after setting them.
                 */
                if ((inp->inp_socket->so_options &
                    (SO_REUSEPORT|SO_REUSEPORT_LB|SO_REUSEADDR)) == 0) {
                        INP_RUNLOCK(inp);
                        break;
                }
        }

        if (appends == 0) {
                /*
                 * No matching pcb found; discard datagram.  (No need
                 * to send an ICMP Port Unreachable for a broadcast
                 * or multicast datagram.)
                 */
                UDPSTAT_INC(udps_noport);
                if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)))
                        UDPSTAT_INC(udps_noportmcast);
                else
                        UDPSTAT_INC(udps_noportbcast);
        }
        m_freem(m);

        return (IPPROTO_DONE);
}

static int
udp_input(struct mbuf **mp, int *offp, int proto)
{
        struct ip *ip;
        struct udphdr *uh;
        struct ifnet *ifp;
        struct inpcb *inp;
        uint16_t len, ip_len;
        struct inpcbinfo *pcbinfo;
        struct sockaddr_in udp_in[2];
        struct mbuf *m;
        struct m_tag *fwd_tag;
        int cscov_partial, iphlen, lookupflags;

        m = *mp;
        iphlen = *offp;
        ifp = m->m_pkthdr.rcvif;
        *mp = NULL;
        UDPSTAT_INC(udps_ipackets);

        /*
         * 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);
                iphlen = sizeof(struct ip);
        }

        /*
         * Get IP and UDP header together in first mbuf.
         */
        if (m->m_len < iphlen + sizeof(struct udphdr)) {
                if ((m = m_pullup(m, iphlen + sizeof(struct udphdr))) == NULL) {
                        UDPSTAT_INC(udps_hdrops);
                        return (IPPROTO_DONE);
                }
        }
        ip = mtod(m, struct ip *);
        uh = (struct udphdr *)((caddr_t)ip + iphlen);
        cscov_partial = (proto == IPPROTO_UDPLITE) ? 1 : 0;

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

        /*
         * Construct sockaddr format source address.  Stuff source address
         * and datagram in user buffer.
         */
        bzero(&udp_in[0], sizeof(struct sockaddr_in) * 2);
        udp_in[0].sin_len = sizeof(struct sockaddr_in);
        udp_in[0].sin_family = AF_INET;
        udp_in[0].sin_port = uh->uh_sport;
        udp_in[0].sin_addr = ip->ip_src;
        udp_in[1].sin_len = sizeof(struct sockaddr_in);
        udp_in[1].sin_family = AF_INET;
        udp_in[1].sin_port = uh->uh_dport;
        udp_in[1].sin_addr = ip->ip_dst;

        /*
         * Make mbuf data length reflect UDP length.  If not enough data to
         * reflect UDP length, drop.
         */
        len = ntohs((u_short)uh->uh_ulen);
        ip_len = ntohs(ip->ip_len) - iphlen;
        if (proto == IPPROTO_UDPLITE && (len == 0 || len == ip_len)) {
                /* Zero means checksum over the complete packet. */
                if (len == 0)
                        len = ip_len;
                cscov_partial = 0;
        }
        if (ip_len != len) {
                if (len > ip_len || len < sizeof(struct udphdr)) {
                        UDPSTAT_INC(udps_badlen);
                        goto badunlocked;
                }
                if (proto == IPPROTO_UDP)
                        m_adj(m, len - ip_len);
        }

        /*
         * Checksum extended UDP header and data.
         */
        if (uh->uh_sum) {
                u_short uh_sum;

                if ((m->m_pkthdr.csum_flags & CSUM_DATA_VALID) &&
                    !cscov_partial) {
                        if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR)
                                uh_sum = m->m_pkthdr.csum_data;
                        else
                                uh_sum = in_pseudo(ip->ip_src.s_addr,
                                    ip->ip_dst.s_addr, htonl((u_short)len +
                                    m->m_pkthdr.csum_data + proto));
                        uh_sum ^= 0xffff;
                } else if (m->m_pkthdr.csum_flags & CSUM_IP_UDP) {
                        /*
                         * Packet from local host (maybe from a VM).
                         * Checksum not required.
                         */
                        uh_sum = 0;
                } else {
                        char b[offsetof(struct ipovly, ih_src)];
                        struct ipovly *ipov = (struct ipovly *)ip;

                        memcpy(b, ipov, sizeof(b));
                        bzero(ipov, sizeof(ipov->ih_x1));
                        ipov->ih_len = (proto == IPPROTO_UDP) ?
                            uh->uh_ulen : htons(ip_len);
                        uh_sum = in_cksum(m, len + sizeof (struct ip));
                        memcpy(ipov, b, sizeof(b));
                }
                if (uh_sum) {
                        UDPSTAT_INC(udps_badsum);
                        m_freem(m);
                        return (IPPROTO_DONE);
                }
        } else {
                if (proto == IPPROTO_UDP) {
                        UDPSTAT_INC(udps_nosum);
                } else {
                        /* UDPLite requires a checksum */
                        /* XXX: What is the right UDPLite MIB counter here? */
                        m_freem(m);
                        return (IPPROTO_DONE);
                }
        }

        if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) ||
            in_ifnet_broadcast(ip->ip_dst, ifp))
                return (udp_multi_input(m, proto, udp_in));

        pcbinfo = udp_get_inpcbinfo(proto);

        /*
         * Locate pcb for datagram.
         */
        lookupflags = INPLOOKUP_RLOCKPCB |
            (V_udp_bind_all_fibs ? 0 : INPLOOKUP_FIB);

        /*
         * Grab info from PACKET_TAG_IPFORWARD tag prepended to the chain.
         */
        if ((m->m_flags & M_IP_NEXTHOP) &&
            (fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL)) != NULL) {
                struct sockaddr_in *next_hop;

                next_hop = (struct sockaddr_in *)(fwd_tag + 1);

                /*
                 * Transparently forwarded. Pretend to be the destination.
                 * Already got one like this?
                 */
                inp = in_pcblookup_mbuf(pcbinfo, ip->ip_src, uh->uh_sport,
                    ip->ip_dst, uh->uh_dport, lookupflags, ifp, m);
                if (!inp) {
                        /*
                         * It's new.  Try to find the ambushing socket.
                         * Because we've rewritten the destination address,
                         * any hardware-generated hash is ignored.
                         */
                        inp = in_pcblookup(pcbinfo, ip->ip_src,
                            uh->uh_sport, next_hop->sin_addr,
                            next_hop->sin_port ? htons(next_hop->sin_port) :
                            uh->uh_dport, INPLOOKUP_WILDCARD | lookupflags,
                            ifp);
                }
                /* Remove the tag from the packet. We don't need it anymore. */
                m_tag_delete(m, fwd_tag);
                m->m_flags &= ~M_IP_NEXTHOP;
        } else
                inp = in_pcblookup_mbuf(pcbinfo, ip->ip_src, uh->uh_sport,
                    ip->ip_dst, uh->uh_dport, INPLOOKUP_WILDCARD |
                    lookupflags, ifp, m);
        if (inp == NULL) {
                if (V_udp_log_in_vain) {
                        char src[INET_ADDRSTRLEN];
                        char dst[INET_ADDRSTRLEN];

                        log(LOG_INFO,
                            "Connection attempt to UDP %s:%d from %s:%d\n",
                            inet_ntoa_r(ip->ip_dst, dst), ntohs(uh->uh_dport),
                            inet_ntoa_r(ip->ip_src, src), ntohs(uh->uh_sport));
                }
                if (proto == IPPROTO_UDPLITE)
                        UDPLITE_PROBE(receive, NULL, NULL, ip, NULL, uh);
                else
                        UDP_PROBE(receive, NULL, NULL, ip, NULL, uh);
                UDPSTAT_INC(udps_noport);
                if (m->m_flags & M_MCAST) {
                        UDPSTAT_INC(udps_noportmcast);
                        goto badunlocked;
                }
                if (m->m_flags & M_BCAST) {
                        UDPSTAT_INC(udps_noportbcast);
                        goto badunlocked;
                }
                if (V_udp_blackhole && (V_udp_blackhole_local ||
                    !in_localip(ip->ip_src)))
                        goto badunlocked;
                if (badport_bandlim(BANDLIM_ICMP_UNREACH) < 0)
                        goto badunlocked;
                icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_PORT, 0, 0);
                return (IPPROTO_DONE);
        }

        /*
         * Check the minimum TTL for socket.
         */
        INP_RLOCK_ASSERT(inp);
        if (inp->inp_ip_minttl && inp->inp_ip_minttl > ip->ip_ttl) {
                if (proto == IPPROTO_UDPLITE)
                        UDPLITE_PROBE(receive, NULL, inp, ip, inp, uh);
                else
                        UDP_PROBE(receive, NULL, inp, ip, inp, uh);
                INP_RUNLOCK(inp);
                m_freem(m);
                return (IPPROTO_DONE);
        }
        if (cscov_partial) {
                struct udpcb *up;

                up = intoudpcb(inp);
                if (up->u_rxcslen == 0 || up->u_rxcslen > len) {
                        INP_RUNLOCK(inp);
                        m_freem(m);
                        return (IPPROTO_DONE);
                }
        }

        if (proto == IPPROTO_UDPLITE)
                UDPLITE_PROBE(receive, NULL, inp, ip, inp, uh);
        else
                UDP_PROBE(receive, NULL, inp, ip, inp, uh);
        if (!udp_append(inp, ip, m, iphlen, udp_in))
                INP_RUNLOCK(inp);
        return (IPPROTO_DONE);

badunlocked:
        m_freem(m);
        return (IPPROTO_DONE);
}
#endif /* INET */

/*
 * Notify a udp user of an asynchronous error; just wake up so that they can
 * collect error status.
 */
struct inpcb *
udp_notify(struct inpcb *inp, int errno)
{

        INP_WLOCK_ASSERT(inp);
        if ((errno == EHOSTUNREACH || errno == ENETUNREACH ||
             errno == EHOSTDOWN) && inp->inp_route.ro_nh) {
                NH_FREE(inp->inp_route.ro_nh);
                inp->inp_route.ro_nh = (struct nhop_object *)NULL;
        }

        inp->inp_socket->so_error = errno;
        sorwakeup(inp->inp_socket);
        sowwakeup(inp->inp_socket);
        return (inp);
}

#ifdef INET
static void
udp_common_ctlinput(struct icmp *icmp, struct inpcbinfo *pcbinfo)
{
        struct ip *ip = &icmp->icmp_ip;
        struct udphdr *uh;
        struct inpcb *inp;

        if (icmp_errmap(icmp) == 0)
                return;

        uh = (struct udphdr *)((caddr_t)ip + (ip->ip_hl << 2));
        inp = in_pcblookup(pcbinfo, ip->ip_dst, uh->uh_dport, ip->ip_src,
            uh->uh_sport, INPLOOKUP_WLOCKPCB, NULL);
        if (inp != NULL) {
                INP_WLOCK_ASSERT(inp);
                if (inp->inp_socket != NULL)
                        udp_notify(inp, icmp_errmap(icmp));
                INP_WUNLOCK(inp);
        } else {
                inp = in_pcblookup(pcbinfo, ip->ip_dst, uh->uh_dport,
                    ip->ip_src, uh->uh_sport,
                    INPLOOKUP_WILDCARD | INPLOOKUP_RLOCKPCB, NULL);
                if (inp != NULL) {
                        struct udpcb *up;
                        udp_tun_icmp_t *func;

                        up = intoudpcb(inp);
                        func = up->u_icmp_func;
                        INP_RUNLOCK(inp);
                        if (func != NULL)
                                func(icmp);
                }
        }
}

static void
udp_ctlinput(struct icmp *icmp)
{

        return (udp_common_ctlinput(icmp, &V_udbinfo));
}

static void
udplite_ctlinput(struct icmp *icmp)
{

        return (udp_common_ctlinput(icmp, &V_ulitecbinfo));
}
#endif /* INET */

static int
udp_pcblist(SYSCTL_HANDLER_ARGS)
{
        struct inpcbinfo *pcbinfo = udp_get_inpcbinfo(arg2);
        struct inpcb_iterator inpi = INP_ALL_ITERATOR(pcbinfo,
            INPLOOKUP_RLOCKPCB);
        struct xinpgen xig;
        struct inpcb *inp;
        int error;

        if (req->newptr != 0)
                return (EPERM);

        if (req->oldptr == 0) {
                int n;

                n = pcbinfo->ipi_count;
                n += imax(n / 8, 10);
                req->oldidx = 2 * (sizeof xig) + n * sizeof(struct xinpcb);
                return (0);
        }

        if ((error = sysctl_wire_old_buffer(req, 0)) != 0)
                return (error);

        bzero(&xig, sizeof(xig));
        xig.xig_len = sizeof xig;
        xig.xig_count = pcbinfo->ipi_count;
        xig.xig_gen = pcbinfo->ipi_gencnt;
        xig.xig_sogen = so_gencnt;
        error = SYSCTL_OUT(req, &xig, sizeof xig);
        if (error)
                return (error);

        while ((inp = inp_next(&inpi)) != NULL) {
                if (inp->inp_gencnt <= xig.xig_gen &&
                    cr_canseeinpcb(req->td->td_ucred, inp) == 0) {
                        struct xinpcb xi;

                        in_pcbtoxinpcb(inp, &xi);
                        error = SYSCTL_OUT(req, &xi, sizeof xi);
                        if (error) {
                                INP_RUNLOCK(inp);
                                break;
                        }
                }
        }

        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.
                 */
                xig.xig_gen = pcbinfo->ipi_gencnt;
                xig.xig_sogen = so_gencnt;
                xig.xig_count = pcbinfo->ipi_count;
                error = SYSCTL_OUT(req, &xig, sizeof xig);
        }

        return (error);
}

SYSCTL_PROC(_net_inet_udp, UDPCTL_PCBLIST, pcblist,
    CTLTYPE_OPAQUE | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, IPPROTO_UDP,
    udp_pcblist, "S,xinpcb",
    "List of active UDP sockets");

SYSCTL_PROC(_net_inet_udplite, OID_AUTO, pcblist,
    CTLTYPE_OPAQUE | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, IPPROTO_UDPLITE,
    udp_pcblist, "S,xinpcb",
    "List of active UDP-Lite sockets");

#ifdef INET
static int
udp_getcred(SYSCTL_HANDLER_ARGS)
{
        struct xucred xuc;
        struct sockaddr_in addrs[2];
        struct epoch_tracker et;
        struct inpcb *inp;
        int error;

        if (req->newptr == NULL)
                return (EINVAL);
        error = priv_check(req->td, PRIV_NETINET_GETCRED);
        if (error)
                return (error);
        error = SYSCTL_IN(req, addrs, sizeof(addrs));
        if (error)
                return (error);
        NET_EPOCH_ENTER(et);
        inp = in_pcblookup(&V_udbinfo, addrs[1].sin_addr, addrs[1].sin_port,
            addrs[0].sin_addr, addrs[0].sin_port,
            INPLOOKUP_WILDCARD | INPLOOKUP_RLOCKPCB, NULL);
        NET_EPOCH_EXIT(et);
        if (inp != NULL) {
                INP_RLOCK_ASSERT(inp);
                if (inp->inp_socket == NULL)
                        error = ENOENT;
                if (error == 0)
                        error = cr_canseeinpcb(req->td->td_ucred, inp);
                if (error == 0)
                        cru2x(inp->inp_cred, &xuc);
                INP_RUNLOCK(inp);
        } else
                error = ENOENT;
        if (error == 0)
                error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred));
        return (error);
}

SYSCTL_PROC(_net_inet_udp, OID_AUTO, getcred,
    CTLTYPE_OPAQUE | CTLFLAG_RW | CTLFLAG_PRISON | CTLFLAG_MPSAFE,
    0, 0, udp_getcred, "S,xucred",
    "Get the xucred of a UDP connection");
#endif /* INET */

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

        error = 0;
        isudplite = (so->so_proto->pr_protocol == IPPROTO_UDPLITE) ? 1 : 0;
        inp = sotoinpcb(so);
        KASSERT(inp != NULL, ("%s: inp == NULL", __func__));
        INP_WLOCK(inp);
        if (sopt->sopt_level != so->so_proto->pr_protocol) {
#ifdef INET6
                if (INP_CHECK_SOCKAF(so, AF_INET6)) {
                        INP_WUNLOCK(inp);
                        error = ip6_ctloutput(so, sopt);
                }
#endif
#if defined(INET) && defined(INET6)
                else
#endif
#ifdef INET
                {
                        INP_WUNLOCK(inp);
                        error = ip_ctloutput(so, sopt);
                }
#endif
                return (error);
        }

        switch (sopt->sopt_dir) {
        case SOPT_SET:
                switch (sopt->sopt_name) {
#if defined(IPSEC) || defined(IPSEC_SUPPORT)
#if defined(INET) || defined(INET6)
                case UDP_ENCAP:
#ifdef INET
                        if (INP_SOCKAF(so) == AF_INET) {
                                if (!IPSEC_ENABLED(ipv4)) {
                                        INP_WUNLOCK(inp);
                                        return (ENOPROTOOPT);
                                }
                                error = UDPENCAP_PCBCTL(ipv4, inp, sopt);
                                break;
                        }
#endif /* INET */
#ifdef INET6
                        if (INP_SOCKAF(so) == AF_INET6) {
                                if (!IPSEC_ENABLED(ipv6)) {
                                        INP_WUNLOCK(inp);
                                        return (ENOPROTOOPT);
                                }
                                error = UDPENCAP_PCBCTL(ipv6, inp, sopt);
                                break;
                        }
#endif /* INET6 */
                        INP_WUNLOCK(inp);
                        return (EINVAL);
#endif /* INET || INET6 */

#endif /* IPSEC */
                case UDPLITE_SEND_CSCOV:
                case UDPLITE_RECV_CSCOV:
                        if (!isudplite) {
                                INP_WUNLOCK(inp);
                                error = ENOPROTOOPT;
                                break;
                        }
                        INP_WUNLOCK(inp);
                        error = sooptcopyin(sopt, &optval, sizeof(optval),
                            sizeof(optval));
                        if (error != 0)
                                break;
                        inp = sotoinpcb(so);
                        KASSERT(inp != NULL, ("%s: inp == NULL", __func__));
                        INP_WLOCK(inp);
                        up = intoudpcb(inp);
                        KASSERT(up != NULL, ("%s: up == NULL", __func__));
                        if ((optval != 0 && optval < 8) || (optval > 65535)) {
                                INP_WUNLOCK(inp);
                                error = EINVAL;
                                break;
                        }
                        if (sopt->sopt_name == UDPLITE_SEND_CSCOV)
                                up->u_txcslen = optval;
                        else
                                up->u_rxcslen = optval;
                        INP_WUNLOCK(inp);
                        break;
                default:
                        INP_WUNLOCK(inp);
                        error = ENOPROTOOPT;
                        break;
                }
                break;
        case SOPT_GET:
                switch (sopt->sopt_name) {
#if defined(IPSEC) || defined(IPSEC_SUPPORT)
#if defined(INET) || defined(INET6)
                case UDP_ENCAP:
#ifdef INET
                        if (INP_SOCKAF(so) == AF_INET) {
                                if (!IPSEC_ENABLED(ipv4)) {
                                        INP_WUNLOCK(inp);
                                        return (ENOPROTOOPT);
                                }
                                error = UDPENCAP_PCBCTL(ipv4, inp, sopt);
                                break;
                        }
#endif /* INET */
#ifdef INET6
                        if (INP_SOCKAF(so) == AF_INET6) {
                                if (!IPSEC_ENABLED(ipv6)) {
                                        INP_WUNLOCK(inp);
                                        return (ENOPROTOOPT);
                                }
                                error = UDPENCAP_PCBCTL(ipv6, inp, sopt);
                                break;
                        }
#endif /* INET6 */
                        INP_WUNLOCK(inp);
                        return (EINVAL);
#endif /* INET || INET6 */

#endif /* IPSEC */
                case UDPLITE_SEND_CSCOV:
                case UDPLITE_RECV_CSCOV:
                        if (!isudplite) {
                                INP_WUNLOCK(inp);
                                error = ENOPROTOOPT;
                                break;
                        }
                        up = intoudpcb(inp);
                        KASSERT(up != NULL, ("%s: up == NULL", __func__));
                        if (sopt->sopt_name == UDPLITE_SEND_CSCOV)
                                optval = up->u_txcslen;
                        else
                                optval = up->u_rxcslen;
                        INP_WUNLOCK(inp);
                        error = sooptcopyout(sopt, &optval, sizeof(optval));
                        break;
                default:
                        INP_WUNLOCK(inp);
                        error = ENOPROTOOPT;
                        break;
                }
                break;
        }
        return (error);
}

#ifdef INET
#ifdef INET6
/* The logic here is derived from ip6_setpktopt(). See comments there. */
static int
udp_v4mapped_pktinfo(struct cmsghdr *cm, struct sockaddr_in * src,
    struct inpcb *inp, int flags)
{
        struct ifnet *ifp;
        struct in6_pktinfo *pktinfo;
        struct in_addr ia;

        NET_EPOCH_ASSERT();

        if ((flags & PRUS_IPV6) == 0)
                return (0);

        if (cm->cmsg_level != IPPROTO_IPV6)
                return (0);

        if  (cm->cmsg_type != IPV6_2292PKTINFO &&
            cm->cmsg_type != IPV6_PKTINFO)
                return (0);

        if (cm->cmsg_len !=
            CMSG_LEN(sizeof(struct in6_pktinfo)))
                return (EINVAL);

        pktinfo = (struct in6_pktinfo *)CMSG_DATA(cm);
        if (!IN6_IS_ADDR_V4MAPPED(&pktinfo->ipi6_addr) &&
            !IN6_IS_ADDR_UNSPECIFIED(&pktinfo->ipi6_addr))
                return (EINVAL);

        /* Validate the interface index if specified. */
        if (pktinfo->ipi6_ifindex) {
                ifp = ifnet_byindex(pktinfo->ipi6_ifindex);
                if (ifp == NULL)
                        return (ENXIO);
        } else
                ifp = NULL;
        if (ifp != NULL && !IN6_IS_ADDR_UNSPECIFIED(&pktinfo->ipi6_addr)) {
                ia.s_addr = pktinfo->ipi6_addr.s6_addr32[3];
                if (!in_ifhasaddr(ifp, ia))
                        return (EADDRNOTAVAIL);
        }

        bzero(src, sizeof(*src));
        src->sin_family = AF_INET;
        src->sin_len = sizeof(*src);
        src->sin_port = inp->inp_lport;
        src->sin_addr.s_addr = pktinfo->ipi6_addr.s6_addr32[3];

        return (0);
}
#endif  /* INET6 */

int
udp_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *addr,
    struct mbuf *control, struct thread *td)
{
        struct inpcb *inp;
        struct udpiphdr *ui;
        int len, error = 0;
        struct in_addr faddr, laddr;
        struct cmsghdr *cm;
        struct inpcbinfo *pcbinfo;
        struct sockaddr_in *sin, src;
        struct epoch_tracker et;
        int cscov_partial = 0;
        int ipflags = 0;
        u_short fport, lport;
        u_char tos, vflagsav;
        uint8_t pr;
        uint16_t cscov = 0;
        uint32_t hash_val, hash_type, flowid = 0;
        uint8_t flowtype = M_HASHTYPE_NONE;
        bool use_cached_route;

        inp = sotoinpcb(so);
        KASSERT(inp != NULL, ("udp_send: inp == NULL"));

        if (addr != NULL) {
                if (addr->sa_family != AF_INET)
                        error = EAFNOSUPPORT;
                else if (addr->sa_len != sizeof(struct sockaddr_in))
                        error = EINVAL;
                if (__predict_false(error != 0)) {
                        m_freem(control);
                        m_freem(m);
                        return (error);
                }
        }

        len = m->m_pkthdr.len;
        if (len + sizeof(struct udpiphdr) > IP_MAXPACKET) {
                if (control)
                        m_freem(control);
                m_freem(m);
                return (EMSGSIZE);
        }

        src.sin_family = 0;
        sin = (struct sockaddr_in *)addr;

        /*
         * udp_send() may need to bind the current inpcb.  As such, we don't
         * know up front whether we will need the pcbinfo lock or not.  Do any
         * work to decide what is needed up front before acquiring any locks.
         *
         * We will need network epoch in either case, to safely lookup into
         * pcb hash.
         */
        use_cached_route = sin == NULL || (inp->inp_laddr.s_addr == INADDR_ANY && inp->inp_lport == 0);
        if (use_cached_route || (flags & PRUS_IPV6) != 0)
                INP_WLOCK(inp);
        else
                INP_RLOCK(inp);
        NET_EPOCH_ENTER(et);
#ifdef INET6
        if ((flags & PRUS_IPV6) != 0) {
                if ((inp->in6p_outputopts != NULL) &&
                    (inp->in6p_outputopts->ip6po_tclass != -1))
                        tos = (u_char)inp->in6p_outputopts->ip6po_tclass;
                else
                        tos = 0;
        } else {
                tos = inp->inp_ip_tos;
        }
#else
        tos = inp->inp_ip_tos;
#endif
        if (control != NULL) {
                /*
                 * XXX: Currently, we assume all the optional information is
                 * stored in a single mbuf.
                 */
                if (control->m_next) {
                        m_freem(control);
                        error = EINVAL;
                        goto release;
                }
                for (; control->m_len > 0;
                    control->m_data += CMSG_ALIGN(cm->cmsg_len),
                    control->m_len -= CMSG_ALIGN(cm->cmsg_len)) {
                        cm = mtod(control, struct cmsghdr *);
                        if (control->m_len < sizeof(*cm) || cm->cmsg_len == 0
                            || cm->cmsg_len > control->m_len) {
                                error = EINVAL;
                                break;
                        }
#ifdef INET6
                        error = udp_v4mapped_pktinfo(cm, &src, inp, flags);
                        if (error != 0)
                                break;
                        if (((flags & PRUS_IPV6) != 0) &&
                            (cm->cmsg_level == IPPROTO_IPV6) &&
                            (cm->cmsg_type == IPV6_TCLASS)) {
                                int tclass;

                                if (cm->cmsg_len != CMSG_LEN(sizeof(int))) {
                                        error = EINVAL;
                                        break;
                                }
                                tclass = *(int *)CMSG_DATA(cm);
                                if (tclass < -1 || tclass > 255) {
                                        error = EINVAL;
                                        break;
                                }
                                if (tclass != -1)
                                        tos = (u_char)tclass;
                        }
#endif
                        if (cm->cmsg_level != IPPROTO_IP)
                                continue;

                        switch (cm->cmsg_type) {
                        case IP_SENDSRCADDR:
                                if (cm->cmsg_len !=
                                    CMSG_LEN(sizeof(struct in_addr))) {
                                        error = EINVAL;
                                        break;
                                }
                                bzero(&src, sizeof(src));
                                src.sin_family = AF_INET;
                                src.sin_len = sizeof(src);
                                src.sin_port = inp->inp_lport;
                                src.sin_addr =
                                    *(struct in_addr *)CMSG_DATA(cm);
                                break;

                        case IP_TOS:
                                if (cm->cmsg_len != CMSG_LEN(sizeof(u_char))) {
                                        error = EINVAL;
                                        break;
                                }
                                tos = *(u_char *)CMSG_DATA(cm);
                                break;

                        case IP_FLOWID:
                                if (cm->cmsg_len != CMSG_LEN(sizeof(uint32_t))) {
                                        error = EINVAL;
                                        break;
                                }
                                flowid = *(uint32_t *) CMSG_DATA(cm);
                                break;

                        case IP_FLOWTYPE:
                                if (cm->cmsg_len != CMSG_LEN(sizeof(uint32_t))) {
                                        error = EINVAL;
                                        break;
                                }
                                flowtype = *(uint32_t *) CMSG_DATA(cm);
                                break;

#ifdef  RSS
                        case IP_RSSBUCKETID:
                                if (cm->cmsg_len != CMSG_LEN(sizeof(uint32_t))) {
                                        error = EINVAL;
                                        break;
                                }
                                /* This is just a placeholder for now */
                                break;
#endif  /* RSS */
                        default:
                                error = ENOPROTOOPT;
                                break;
                        }
                        if (error)
                                break;
                }
                m_freem(control);
                control = NULL;
        }
        if (error)
                goto release;

        pr = inp->inp_socket->so_proto->pr_protocol;
        pcbinfo = udp_get_inpcbinfo(pr);

        /*
         * If the IP_SENDSRCADDR control message was specified, override the
         * source address for this datagram.  Its use is invalidated if the
         * address thus specified is incomplete or clobbers other inpcbs.
         */
        laddr = inp->inp_laddr;
        lport = inp->inp_lport;
        if (src.sin_family == AF_INET) {
                if ((lport == 0) ||
                    (laddr.s_addr == INADDR_ANY &&
                     src.sin_addr.s_addr == INADDR_ANY)) {
                        error = EINVAL;
                        goto release;
                }
                if ((flags & PRUS_IPV6) != 0) {
                        vflagsav = inp->inp_vflag;
                        inp->inp_vflag |= INP_IPV4;
                        inp->inp_vflag &= ~INP_IPV6;
                }
                INP_HASH_WLOCK(pcbinfo);
                error = in_pcbbind_setup(inp, &src, &laddr.s_addr, &lport,
                    V_udp_bind_all_fibs ? 0 : INPBIND_FIB, td->td_ucred);
                INP_HASH_WUNLOCK(pcbinfo);
                if ((flags & PRUS_IPV6) != 0)
                        inp->inp_vflag = vflagsav;
                if (error)
                        goto release;
        }

        /*
         * If a UDP socket has been connected, then a local address/port will
         * have been selected and bound.
         *
         * If a UDP socket has not been connected to, then an explicit
         * destination address must be used, in which case a local
         * address/port may not have been selected and bound.
         */
        if (sin != NULL) {
                INP_LOCK_ASSERT(inp);
                if (inp->inp_faddr.s_addr != INADDR_ANY) {
                        error = EISCONN;
                        goto release;
                }

                /*
                 * Jail may rewrite the destination address, so let it do
                 * that before we use it.
                 */
                error = prison_remote_ip4(td->td_ucred, &sin->sin_addr);
                if (error)
                        goto release;
                /*
                 * sendto(2) on unconnected UDP socket results in implicit
                 * binding to INADDR_ANY and anonymous port.  This has two
                 * side effects:
                 * 1) after first sendto(2) the socket will receive datagrams
                 *    destined to the selected port.
                 * 2) subsequent sendto(2) calls will use the same source port.
                 */
                if (inp->inp_lport == 0) {
                        struct sockaddr_in wild = {
                                .sin_family = AF_INET,
                                .sin_len = sizeof(struct sockaddr_in),
                        };

                        INP_HASH_WLOCK(pcbinfo);
                        error = in_pcbbind(inp, &wild, V_udp_bind_all_fibs ?
                            0 : INPBIND_FIB, td->td_ucred);
                        INP_HASH_WUNLOCK(pcbinfo);
                        if (error)
                                goto release;
                        lport = inp->inp_lport;
                        laddr = inp->inp_laddr;
                }
                if (laddr.s_addr == INADDR_ANY) {
                        error = in_pcbladdr(inp, &sin->sin_addr, &laddr,
                            td->td_ucred);
                        if (error)
                                goto release;
                }
                faddr = sin->sin_addr;
                fport = sin->sin_port;
        } else {
                INP_LOCK_ASSERT(inp);
                faddr = inp->inp_faddr;
                fport = inp->inp_fport;
                if (faddr.s_addr == INADDR_ANY) {
                        error = ENOTCONN;
                        goto release;
                }
        }

        /*
         * Calculate data length and get a mbuf for UDP, IP, and possible
         * link-layer headers.  Immediate slide the data pointer back forward
         * since we won't use that space at this layer.
         */
        M_PREPEND(m, sizeof(struct udpiphdr) + max_linkhdr, M_NOWAIT);
        if (m == NULL) {
                error = ENOBUFS;
                goto release;
        }
        m->m_data += max_linkhdr;
        m->m_len -= max_linkhdr;
        m->m_pkthdr.len -= max_linkhdr;

        /*
         * Fill in mbuf with extended UDP header and addresses and length put
         * into network format.
         */
        ui = mtod(m, struct udpiphdr *);
        /*
         * Filling only those fields of udpiphdr that participate in the
         * checksum calculation. The rest must be zeroed and will be filled
         * later.
         */
        bzero(ui->ui_x1, sizeof(ui->ui_x1));
        ui->ui_pr = pr;
        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));
        if (pr == IPPROTO_UDPLITE) {
                struct udpcb *up;
                uint16_t plen;

                up = intoudpcb(inp);
                cscov = up->u_txcslen;
                plen = (u_short)len + sizeof(struct udphdr);
                if (cscov >= plen)
                        cscov = 0;
                ui->ui_len = htons(plen);
                ui->ui_ulen = htons(cscov);
                /*
                 * For UDP-Lite, checksum coverage length of zero means
                 * the entire UDPLite packet is covered by the checksum.
                 */
                cscov_partial = (cscov == 0) ? 0 : 1;
        }

        if (inp->inp_socket->so_options & SO_DONTROUTE)
                ipflags |= IP_ROUTETOIF;
        if (inp->inp_socket->so_options & SO_BROADCAST)
                ipflags |= IP_ALLOWBROADCAST;
        if (inp->inp_flags & INP_ONESBCAST)
                ipflags |= IP_SENDONES;

#ifdef MAC
        mac_inpcb_create_mbuf(inp, m);
#endif

        /*
         * Set up checksum and output datagram.
         */
        ui->ui_sum = 0;
        if (pr == IPPROTO_UDPLITE) {
                if (inp->inp_flags & INP_ONESBCAST)
                        faddr.s_addr = INADDR_BROADCAST;
                if (cscov_partial) {
                        if ((ui->ui_sum = in_cksum(m, sizeof(struct ip) + cscov)) == 0)
                                ui->ui_sum = 0xffff;
                } else {
                        if ((ui->ui_sum = in_cksum(m, sizeof(struct udpiphdr) + len)) == 0)
                                ui->ui_sum = 0xffff;
                }
        } else if (V_udp_cksum) {
                if (inp->inp_flags & INP_ONESBCAST)
                        faddr.s_addr = INADDR_BROADCAST;
                ui->ui_sum = in_pseudo(ui->ui_src.s_addr, faddr.s_addr,
                    htons((u_short)len + sizeof(struct udphdr) + pr));
                m->m_pkthdr.csum_flags = CSUM_UDP;
                m->m_pkthdr.csum_data = offsetof(struct udphdr, uh_sum);
        }
        /*
         * After finishing the checksum computation, fill the remaining fields
         * of udpiphdr.
         */
        ((struct ip *)ui)->ip_v = IPVERSION;
        ((struct ip *)ui)->ip_tos = tos;
        ((struct ip *)ui)->ip_len = htons(sizeof(struct udpiphdr) + len);
        if (inp->inp_flags & INP_DONTFRAG)
                ((struct ip *)ui)->ip_off |= htons(IP_DF);
        ((struct ip *)ui)->ip_ttl = inp->inp_ip_ttl;
        UDPSTAT_INC(udps_opackets);

        /*
         * Setup flowid / RSS information for outbound socket.
         *
         * Once the UDP code decides to set a flowid some other way,
         * this allows the flowid to be overridden by userland.
         */
        if (flowtype != M_HASHTYPE_NONE) {
                m->m_pkthdr.flowid = flowid;
                M_HASHTYPE_SET(m, flowtype);
        } else if (CALC_FLOWID_OUTBOUND_SENDTO) {
                hash_val = fib4_calc_packet_hash(laddr, faddr,
                    lport, fport, pr, &hash_type);
                m->m_pkthdr.flowid = hash_val;
                M_HASHTYPE_SET(m, hash_type);
        }

        /*
         * Don't override with the inp cached flowid value.
         *
         * Depending upon the kind of send being done, the inp
         * flowid/flowtype values may actually not be appropriate
         * for this particular socket send.
         *
         * We should either leave the flowid at zero (which is what is
         * currently done) or set it to some software generated
         * hash value based on the packet contents.
         */
        ipflags |= IP_NODEFAULTFLOWID;

        if (pr == IPPROTO_UDPLITE)
                UDPLITE_PROBE(send, NULL, inp, &ui->ui_i, inp, &ui->ui_u);
        else
                UDP_PROBE(send, NULL, inp, &ui->ui_i, inp, &ui->ui_u);
        error = ip_output(m, inp->inp_options,
            use_cached_route ? &inp->inp_route : NULL, ipflags,
            inp->inp_moptions, inp);
        INP_UNLOCK(inp);
        NET_EPOCH_EXIT(et);
        return (error);

release:
        INP_UNLOCK(inp);
        NET_EPOCH_EXIT(et);
        m_freem(m);
        return (error);
}

void
udp_abort(struct socket *so)
{
        struct inpcb *inp;
        struct inpcbinfo *pcbinfo;

        pcbinfo = udp_get_inpcbinfo(so->so_proto->pr_protocol);
        inp = sotoinpcb(so);
        KASSERT(inp != NULL, ("udp_abort: inp == NULL"));
        INP_WLOCK(inp);
        if (inp->inp_faddr.s_addr != INADDR_ANY) {
                INP_HASH_WLOCK(pcbinfo);
                in_pcbdisconnect(inp);
                INP_HASH_WUNLOCK(pcbinfo);
                soisdisconnected(so);
        }
        INP_WUNLOCK(inp);
}

static int
udp_attach(struct socket *so, int proto, struct thread *td)
{
        static uint32_t udp_flowid;
        struct inpcbinfo *pcbinfo;
        struct inpcb *inp;
        struct udpcb *up;
        int error;

        pcbinfo = udp_get_inpcbinfo(so->so_proto->pr_protocol);
        inp = sotoinpcb(so);
        KASSERT(inp == NULL, ("udp_attach: inp != NULL"));
        error = soreserve(so, udp_sendspace, udp_recvspace);
        if (error)
                return (error);
        error = in_pcballoc(so, pcbinfo);
        if (error)
                return (error);

        inp = sotoinpcb(so);
        inp->inp_ip_ttl = V_ip_defttl;
        inp->inp_flowid = atomic_fetchadd_int(&udp_flowid, 1);
        inp->inp_flowtype = M_HASHTYPE_OPAQUE;
        up = intoudpcb(inp);
        bzero(&up->u_start_zero, u_zero_size);
        INP_WUNLOCK(inp);

        return (0);
}
#endif /* INET */

int
udp_set_kernel_tunneling(struct socket *so, udp_tun_func_t f, udp_tun_icmp_t i, void *ctx)
{
        struct inpcb *inp;
        struct udpcb *up;

        KASSERT(so->so_type == SOCK_DGRAM,
            ("udp_set_kernel_tunneling: !dgram"));
        inp = sotoinpcb(so);
        KASSERT(inp != NULL, ("udp_set_kernel_tunneling: inp == NULL"));
        INP_WLOCK(inp);
        up = intoudpcb(inp);
        if ((f != NULL || i != NULL) && ((up->u_tun_func != NULL) ||
            (up->u_icmp_func != NULL))) {
                INP_WUNLOCK(inp);
                return (EBUSY);
        }
        up->u_tun_func = f;
        up->u_icmp_func = i;
        up->u_tun_ctx = ctx;
        INP_WUNLOCK(inp);
        return (0);
}

#ifdef INET
static int
udp_bind(struct socket *so, struct sockaddr *nam, struct thread *td)
{
        struct inpcb *inp;
        struct inpcbinfo *pcbinfo;
        struct sockaddr_in *sinp;
        int error;

        pcbinfo = udp_get_inpcbinfo(so->so_proto->pr_protocol);
        inp = sotoinpcb(so);
        KASSERT(inp != NULL, ("udp_bind: inp == NULL"));

        sinp = (struct sockaddr_in *)nam;
        if (nam->sa_family != AF_INET) {
                /*
                 * Preserve compatibility with old programs.
                 */
                if (nam->sa_family != AF_UNSPEC ||
                    nam->sa_len < offsetof(struct sockaddr_in, sin_zero) ||
                    sinp->sin_addr.s_addr != INADDR_ANY)
                        return (EAFNOSUPPORT);
                nam->sa_family = AF_INET;
        }
        if (nam->sa_len != sizeof(struct sockaddr_in))
                return (EINVAL);

        INP_WLOCK(inp);
        INP_HASH_WLOCK(pcbinfo);
        error = in_pcbbind(inp, sinp, V_udp_bind_all_fibs ? 0 : INPBIND_FIB,
            td->td_ucred);
        INP_HASH_WUNLOCK(pcbinfo);
        INP_WUNLOCK(inp);
        return (error);
}

static void
udp_close(struct socket *so)
{
        struct inpcb *inp;
        struct inpcbinfo *pcbinfo;

        pcbinfo = udp_get_inpcbinfo(so->so_proto->pr_protocol);
        inp = sotoinpcb(so);
        KASSERT(inp != NULL, ("udp_close: inp == NULL"));
        INP_WLOCK(inp);
        if (inp->inp_faddr.s_addr != INADDR_ANY) {
                INP_HASH_WLOCK(pcbinfo);
                in_pcbdisconnect(inp);
                INP_HASH_WUNLOCK(pcbinfo);
                soisdisconnected(so);
        }
        INP_WUNLOCK(inp);
}

static int
udp_connect(struct socket *so, struct sockaddr *nam, struct thread *td)
{
        struct epoch_tracker et;
        struct inpcb *inp;
        struct inpcbinfo *pcbinfo;
        struct sockaddr_in *sin;
        int error;

        pcbinfo = udp_get_inpcbinfo(so->so_proto->pr_protocol);
        inp = sotoinpcb(so);
        KASSERT(inp != NULL, ("udp_connect: inp == NULL"));

        sin = (struct sockaddr_in *)nam;
        if (sin->sin_family != AF_INET)
                return (EAFNOSUPPORT);
        if (sin->sin_len != sizeof(*sin))
                return (EINVAL);

        INP_WLOCK(inp);
        if (inp->inp_faddr.s_addr != INADDR_ANY) {
                INP_WUNLOCK(inp);
                return (EISCONN);
        }
        error = prison_remote_ip4(td->td_ucred, &sin->sin_addr);
        if (error != 0) {
                INP_WUNLOCK(inp);
                return (error);
        }
        NET_EPOCH_ENTER(et);
        INP_HASH_WLOCK(pcbinfo);
        error = in_pcbconnect(inp, sin, td->td_ucred);
        INP_HASH_WUNLOCK(pcbinfo);
        NET_EPOCH_EXIT(et);
        if (error == 0)
                soisconnected(so);
        INP_WUNLOCK(inp);
        return (error);
}

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

        inp = sotoinpcb(so);
        KASSERT(inp != NULL, ("udp_detach: inp == NULL"));
        KASSERT(inp->inp_faddr.s_addr == INADDR_ANY,
            ("udp_detach: not disconnected"));
        INP_WLOCK(inp);
        in_pcbfree(inp);
}

int
udp_disconnect(struct socket *so)
{
        struct inpcb *inp;
        struct inpcbinfo *pcbinfo;

        pcbinfo = udp_get_inpcbinfo(so->so_proto->pr_protocol);
        inp = sotoinpcb(so);
        KASSERT(inp != NULL, ("udp_disconnect: inp == NULL"));
        INP_WLOCK(inp);
        if (inp->inp_faddr.s_addr == INADDR_ANY) {
                INP_WUNLOCK(inp);
                return (ENOTCONN);
        }
        INP_HASH_WLOCK(pcbinfo);
        in_pcbdisconnect(inp);
        INP_HASH_WUNLOCK(pcbinfo);
        SOCK_LOCK(so);
        so->so_state &= ~SS_ISCONNECTED;                /* XXX */
        SOCK_UNLOCK(so);
        INP_WUNLOCK(inp);
        return (0);
}
#endif /* INET */

int
udp_shutdown(struct socket *so, enum shutdown_how how)
{
        int error;

        SOCK_LOCK(so);
        if (!(so->so_state & SS_ISCONNECTED))
                /*
                 * POSIX mandates us to just return ENOTCONN when shutdown(2) is
                 * invoked on a datagram sockets, however historically we would
                 * actually tear socket down.  This is known to be leveraged by
                 * some applications to unblock process waiting in recv(2) by
                 * other process that it shares that socket with.  Try to meet
                 * both backward-compatibility and POSIX requirements by forcing
                 * ENOTCONN but still flushing buffers and performing wakeup(9).
                 *
                 * XXXGL: it remains unknown what applications expect this
                 * behavior and is this isolated to unix/dgram or inet/dgram or
                 * both.  See: D10351, D3039.
                 */
                error = ENOTCONN;
        else
                error = 0;
        SOCK_UNLOCK(so);

        switch (how) {
        case SHUT_RD:
                sorflush(so);
                break;
        case SHUT_RDWR:
                sorflush(so);
                /* FALLTHROUGH */
        case SHUT_WR:
                socantsendmore(so);
        }

        return (error);
}

#ifdef INET
#define UDP_PROTOSW                                                     \
        .pr_type =              SOCK_DGRAM,                             \
        .pr_flags =             PR_ATOMIC | PR_ADDR | PR_CAPATTACH,     \
        .pr_ctloutput =         udp_ctloutput,                          \
        .pr_abort =             udp_abort,                              \
        .pr_attach =            udp_attach,                             \
        .pr_bind =              udp_bind,                               \
        .pr_connect =           udp_connect,                            \
        .pr_control =           in_control,                             \
        .pr_detach =            udp_detach,                             \
        .pr_disconnect =        udp_disconnect,                         \
        .pr_peeraddr =          in_getpeeraddr,                         \
        .pr_send =              udp_send,                               \
        .pr_soreceive =         soreceive_dgram,                        \
        .pr_sosend =            sosend_dgram,                           \
        .pr_shutdown =          udp_shutdown,                           \
        .pr_sockaddr =          in_getsockaddr,                         \
        .pr_sosetlabel =        in_pcbsosetlabel,                       \
        .pr_close =             udp_close

struct protosw udp_protosw = {
        .pr_protocol =          IPPROTO_UDP,
        UDP_PROTOSW
};

struct protosw udplite_protosw = {
        .pr_protocol =          IPPROTO_UDPLITE,
        UDP_PROTOSW
};

static void
udp_init(void *arg __unused)
{

        IPPROTO_REGISTER(IPPROTO_UDP, udp_input, udp_ctlinput);
        IPPROTO_REGISTER(IPPROTO_UDPLITE, udp_input, udplite_ctlinput);
}
SYSINIT(udp_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, udp_init, NULL);
#endif /* INET */