xref: /src/sys/netinet/udp_usrreq.c

/*	$NetBSD: udp_usrreq.c,v 1.254.2.1 2019/06/10 22:09:47 christos Exp $	*/

/*
 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the project nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)udp_usrreq.c	8.6 (Berkeley) 5/23/95
 */

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

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: udp_usrreq.c,v 1.254.2.1 2019/06/10 22:09:47 christos Exp $");

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

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

#include <net/if.h>

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

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

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

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

int udpcksum = 1;
int udp_do_loopback_cksum = 0;

struct inpcbtable udbtable;

percpu_t *udpstat_percpu;

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

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

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

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

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

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

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

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

static void sysctl_net_inet_udp_setup(struct sysctllog **);

static int
do_udpinit(void)
{

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

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

	return 0;
}

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

	RUN_ONCE(&doudpinit, do_udpinit);
}

void
udp_init(void)
{

	sysctl_net_inet_udp_setup(NULL);

	udp_init_common();
}

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

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

#ifdef INET

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

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

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

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

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

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

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

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

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

	return 0;

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

bad:
	if (m)
		m_freem(m);
	return;

badcsum:
	m_freem(m);
}
#endif

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

			case 1: /* ESP over UDP */
				rcvcnt++;
				goto bad;

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

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

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

bad:
	return rcvcnt;
}
#endif

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

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

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

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

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

	return NULL;
}

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

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

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


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

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

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

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

			default:
				error = EINVAL;
				break;
			}
			break;

		default:
			error = ENOPROTOOPT;
			break;
		}
		break;

	default:
		error = EINVAL;
		break;
	}

end:
	splx(s);
	return error;
}

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

	MCLAIM(m, &udp_tx_mowner);

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

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

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

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

	if (control != NULL) {
		m_freem(control);
		control = NULL;
	}

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

	ro = &inp->inp_route;

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

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

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

 release:
	if (control != NULL)
		m_freem(control);
	m_freem(m);
	return error;
}

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

	KASSERT(sotoinpcb(so) == NULL);

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

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

	error = in_pcballoc(so, &udbtable);
	if (error) {
		return error;
	}
	inp = sotoinpcb(so);
	inp->inp_ip.ip_ttl = ip_defttl;
	KASSERT(solocked(so));

	return error;
}

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

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

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

	panic("udp_accept");

	return EOPNOTSUPP;
}

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

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

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

	return error;
}

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

	return EOPNOTSUPP;
}

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

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

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

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

	return EOPNOTSUPP;
}

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

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

	s = splsoftnet();
	/*soisdisconnected(so);*/
	so->so_state &= ~SS_ISCONNECTED;	/* XXX */
	in_pcbdisconnect(inp);
	inp->inp_laddr = zeroin_addr;		/* XXX */
	in_pcbstate(inp, INP_BOUND);		/* XXX */
	splx(s);

	return 0;
}

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

	KASSERT(solocked(so));

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

	return 0;
}

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

	panic("udp_abort");

	return EOPNOTSUPP;
}

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

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

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

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

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

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

	return 0;
}

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

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

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

	return 0;
}

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

	return EOPNOTSUPP;
}

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

	return EOPNOTSUPP;
}

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

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

	memset(&laddr, 0, sizeof laddr);

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

	splx(s);
	return error;
}

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

	m_freem(m);
	m_freem(control);

	return EOPNOTSUPP;
}

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

	s = splsoftnet();
	mutex_enter(softnet_lock);
	in_pcbpurgeif0(&udbtable, ifp);
#ifdef NET_MPSAFE
	mutex_exit(softnet_lock);
#endif
	in_purgeif(ifp);
#ifdef NET_MPSAFE
	mutex_enter(softnet_lock);
#endif
	in_pcbpurgeif(&udbtable, ifp);
	mutex_exit(softnet_lock);
	splx(s);

	return 0;
}

static int
sysctl_net_inet_udp_stats(SYSCTLFN_ARGS)
{

	return (NETSTAT_SYSCTL(udpstat_percpu, UDP_NSTATS));
}

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

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

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

void
udp_statinc(u_int stat)
{

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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