udp_usrreq.c

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//==========================================================================
//
//      src/sys/netinet/udp_usrreq.c
//
//==========================================================================
//####BSDCOPYRIGHTBEGIN####
//
// -------------------------------------------
//
// Portions of this software may have been derived from OpenBSD, 
// FreeBSD or other sources, and are covered by the appropriate
// copyright disclaimers included herein.
//
// Portions created by Red Hat are
// Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
//
// -------------------------------------------
//
//####BSDCOPYRIGHTEND####
//==========================================================================

/*
 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)udp_usrreq.c	8.6 (Berkeley) 5/23/95
 * $FreeBSD: src/sys/netinet/udp_usrreq.c,v 1.64.2.13 2001/08/08 18:59:54 ghelmer Exp $
 */

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

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

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

#ifdef IPSEC
#include <netinet6/ipsec.h>
#endif /*IPSEC*/

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

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

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

struct	inpcbhead udb;		/* from udp_var.h */

#define	udb6	udb  /* for KAME src sync over BSD*'s */
struct	inpcbinfo udbinfo;

#ifndef UDBHASHSIZE
#define UDBHASHSIZE 16
#endif

struct	udpstat udpstat;	/* from udp_var.h */
SYSCTL_STRUCT(_net_inet_udp, UDPCTL_STATS, stats, CTLFLAG_RD,
    &udpstat, udpstat, "UDP statistics (struct udpstat, netinet/udp_var.h)");


static struct	sockaddr_in udp_in = { sizeof(udp_in), AF_INET };
#ifdef INET6
struct udp_in6 {
	struct sockaddr_in6	uin6_sin;
	u_char			uin6_init_done : 1;
} udp_in6 = {
	{ sizeof(udp_in6.uin6_sin), AF_INET6 },
	0
};
struct udp_ip6 {
	struct ip6_hdr		uip6_ip6;
	u_char			uip6_init_done : 1;
} udp_ip6;
#endif /* INET6 */

static void udp_append __P((struct inpcb *last, struct ip *ip,
			    struct mbuf *n, int off));
#ifdef INET6
static void ip_2_ip6_hdr __P((struct ip6_hdr *ip6, struct ip *ip));
#endif

static int udp_detach __P((struct socket *so));
static	int udp_output __P((struct inpcb *, struct mbuf *, struct sockaddr *,
			    struct mbuf *, struct proc *));

void
udp_init()
{
	LIST_INIT(&udb);
	udbinfo.listhead = &udb;
	udbinfo.hashbase = hashinit(UDBHASHSIZE, M_PCB, &udbinfo.hashmask);
	udbinfo.porthashbase = hashinit(UDBHASHSIZE, M_PCB,
					&udbinfo.porthashmask);
	udbinfo.ipi_zone = zinit("udpcb", sizeof(struct inpcb), maxsockets,
				 ZONE_INTERRUPT, 0);
}

void
udp_input(m, off)
	register struct mbuf *m;
	int off;
{
	int iphlen = off;
	register struct ip *ip;
	register struct udphdr *uh;
	register struct inpcb *inp;
	struct mbuf *opts = 0;
#ifdef INET6
	struct ip6_recvpktopts opts6;
#endif 
	int len;
	struct ip save_ip;
	struct sockaddr *append_sa;

	udpstat.udps_ipackets++;
#ifdef INET6
	bzero(&opts6, sizeof(opts6));
#endif

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

	/*
	 * Get IP and UDP header together in first mbuf.
	 */
	ip = mtod(m, struct ip *);
#ifndef PULLDOWN_TEST
	if (m->m_len < iphlen + sizeof(struct udphdr)) {
		if ((m = m_pullup(m, iphlen + sizeof(struct udphdr))) == 0) {
			udpstat.udps_hdrops++;
			return;
		}
		ip = mtod(m, struct ip *);
	}
	uh = (struct udphdr *)((caddr_t)ip + iphlen);
#else
	IP6_EXTHDR_GET(uh, struct udphdr *, m, iphlen, sizeof(struct udphdr));
	if (!uh) {
		udpstat.udps_hdrops++;
		return;
	}
#endif

	/* 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.
	 */
	len = ntohs((u_short)uh->uh_ulen);
	if (ip->ip_len != len) {
		if (len > ip->ip_len || len < sizeof(struct udphdr)) {
			udpstat.udps_badlen++;
			goto bad;
		}
		m_adj(m, len - ip->ip_len);
		/* ip->ip_len = len; */
	}
	/*
	 * Save a copy of the IP header in case we want restore it
	 * for sending an ICMP error message in response.
	 */
	save_ip = *ip;

	/*
	 * Checksum extended UDP header and data.
	 */
	if (uh->uh_sum) {
		if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID) {
			if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR)
				uh->uh_sum = m->m_pkthdr.csum_data;
			else
	                	uh->uh_sum = in_pseudo(ip->ip_src.s_addr,
				    ip->ip_dst.s_addr, htonl((u_short)len +
				    m->m_pkthdr.csum_data + IPPROTO_UDP));
			uh->uh_sum ^= 0xffff;
		} else {
			char b[9];
			bcopy(((struct ipovly *)ip)->ih_x1, b, 9);
			bzero(((struct ipovly *)ip)->ih_x1, 9);
			((struct ipovly *)ip)->ih_len = uh->uh_ulen;
			uh->uh_sum = in_cksum(m, len + sizeof (struct ip));
			bcopy(b, ((struct ipovly *)ip)->ih_x1, 9);
		}
		if (uh->uh_sum) {
			udpstat.udps_badsum++;
			m_freem(m);
			return;
		}
	} else
		udpstat.udps_nosum++;

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

		/*
		 * Construct sockaddr format source address.
		 */
		udp_in.sin_port = uh->uh_sport;
		udp_in.sin_addr = ip->ip_src;
		/*
		 * Locate pcb(s) for datagram.
		 * (Algorithm copied from raw_intr().)
		 */
		last = NULL;
#ifdef INET6
		udp_in6.uin6_init_done = udp_ip6.uip6_init_done = 0;
#endif
		LIST_FOREACH(inp, &udb, inp_list) {
#ifdef INET6
			if ((inp->inp_vflag & INP_IPV4) == 0)
				continue;
#endif
			if (inp->inp_lport != uh->uh_dport)
				continue;
			if (inp->inp_laddr.s_addr != INADDR_ANY) {
				if (inp->inp_laddr.s_addr !=
				    ip->ip_dst.s_addr)
					continue;
			}
			if (inp->inp_faddr.s_addr != INADDR_ANY) {
				if (inp->inp_faddr.s_addr !=
				    ip->ip_src.s_addr ||
				    inp->inp_fport != uh->uh_sport)
					continue;
			}

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

#ifdef IPSEC
				/* check AH/ESP integrity. */
				if (ipsec4_in_reject_so(m, last->inp_socket))
					ipsecstat.in_polvio++;
					/* do not inject data to pcb */
				else
#endif /*IPSEC*/
				if ((n = m_copy(m, 0, M_COPYALL)) != NULL)
					udp_append(last, ip, n,
						   iphlen +
						   sizeof(struct udphdr));
			}
			last = inp;
			/*
			 * Don't look for additional matches if this one does
			 * not have either the SO_REUSEPORT or SO_REUSEADDR
			 * socket options set.  This heuristic avoids searching
			 * through all pcbs in the common case of a non-shared
			 * port.  It * assumes that an application will never
			 * clear these options after setting them.
			 */
			if ((last->inp_socket->so_options&(SO_REUSEPORT|SO_REUSEADDR)) == 0)
				break;
		}

		if (last == NULL) {
			/*
			 * No matching pcb found; discard datagram.
			 * (No need to send an ICMP Port Unreachable
			 * for a broadcast or multicast datgram.)
			 */
			udpstat.udps_noportbcast++;
			goto bad;
		}
#ifdef IPSEC
		/* check AH/ESP integrity. */
		if (ipsec4_in_reject_so(m, last->inp_socket)) {
			ipsecstat.in_polvio++;
			goto bad;
		}
#endif /*IPSEC*/
		udp_append(last, ip, m, iphlen + sizeof(struct udphdr));
		return;
	}
	/*
	 * Locate pcb for datagram.
	 */
	inp = in_pcblookup_hash(&udbinfo, ip->ip_src, uh->uh_sport,
	    ip->ip_dst, uh->uh_dport, 1, m->m_pkthdr.rcvif);
	if (inp == NULL) {
		if (log_in_vain) {
			char buf[4*sizeof "123"];

			strcpy(buf, inet_ntoa(ip->ip_dst));
			log(LOG_INFO,
			    "Connection attempt to UDP %s:%d from %s:%d\n",
			    buf, ntohs(uh->uh_dport), inet_ntoa(ip->ip_src),
			    ntohs(uh->uh_sport));
		}
		udpstat.udps_noport++;
		if (m->m_flags & (M_BCAST | M_MCAST)) {
			udpstat.udps_noportbcast++;
			goto bad;
		}
#ifdef ICMP_BANDLIM
		if (badport_bandlim(BANDLIM_ICMP_UNREACH) < 0)
			goto bad;
#endif
		if (blackhole)
			goto bad;
		*ip = save_ip;
		ip->ip_len += iphlen;
		icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_PORT, 0, 0);
		return;
	}
#ifdef IPSEC
	if (ipsec4_in_reject_so(m, inp->inp_socket)) {
		ipsecstat.in_polvio++;
		goto bad;
	}
#endif /*IPSEC*/

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

			ip_2_ip6_hdr(&udp_ip6.uip6_ip6, ip);
			savedflags = inp->inp_flags;
			inp->inp_flags &= ~INP_UNMAPPABLEOPTS;
 			ip6_savecontrol(inp, &udp_ip6.uip6_ip6, m,
 					&opts6, NULL);
			inp->inp_flags = savedflags;
		} else
#endif
		ip_savecontrol(inp, &opts, ip, m);
	}
 	m_adj(m, iphlen + sizeof(struct udphdr));
#ifdef INET6
	if (inp->inp_vflag & INP_IPV6) {
		in6_sin_2_v4mapsin6(&udp_in, &udp_in6.uin6_sin);
		append_sa = (struct sockaddr *)&udp_in6;
 		opts = opts6.head;
	} else
#endif
	append_sa = (struct sockaddr *)&udp_in;
	if (sbappendaddr(&inp->inp_socket->so_rcv, append_sa, m, opts) == 0) {
		udpstat.udps_fullsock++;
		goto bad;
	}
	sorwakeup(inp->inp_socket);
	return;
bad:
	m_freem(m);
	if (opts)
		m_freem(opts);
	return;
}

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

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

/*