udp_usrreq.c

早期freebsd实现

/*
 * Copyright (c) 1982, 1986, 1988, 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)udp_usrreq.c	8.4 (Berkeley) 1/21/94
 */

#include <sys/param.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/errno.h>
#include <sys/stat.h>

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

#include <netinet/in.h>
#include <netinet/in_systm.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>

/*
 * UDP protocol implementation.
 * Per RFC 768, August, 1980.
 */
#ifndef	COMPAT_42
int	udpcksum = 1;
#else
int	udpcksum = 0;		/* XXX */
#endif

struct	sockaddr_in udp_in = { sizeof(udp_in), AF_INET };
struct	inpcb *udp_last_inpcb = &udb;

static	void udp_detach __P((struct inpcb *));
static	void udp_notify __P((struct inpcb *, int));
static	struct mbuf *udp_saveopt __P((caddr_t, int, int));

void
udp_init()
{
	udb.inp_next = udb.inp_prev = &udb;
}

void
udp_input(m, iphlen)
	register struct mbuf *m;
	int iphlen;
{
	register struct ip *ip;
	register struct udphdr *uh;
	register struct inpcb *inp;
	struct mbuf *opts = 0;
	int len;
	struct ip save_ip;

	udpstat.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, (struct mbuf *)0);
		iphlen = sizeof(struct ip);
	}

	/*
	 * Get IP and UDP header together in first mbuf.
	 */
	ip = mtod(m, struct ip *);
	if (m->m_len < iphlen + sizeof(struct udphdr)) {
		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);

	/*
	 * 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) {
			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 (udpcksum && uh->uh_sum) {
		((struct ipovly *)ip)->ih_next = 0;
		((struct ipovly *)ip)->ih_prev = 0;
		((struct ipovly *)ip)->ih_x1 = 0;
		((struct ipovly *)ip)->ih_len = uh->uh_ulen;
		if (uh->uh_sum = in_cksum(m, len + sizeof (struct ip))) {
			udpstat.udps_badsum++;
			m_freem(m);
			return;
		}
	}

	if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) ||
	    in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) {
		struct socket *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;
		m->m_len -= sizeof (struct udpiphdr);
		m->m_data += sizeof (struct udpiphdr);
		/*
		 * Locate pcb(s) for datagram.
		 * (Algorithm copied from raw_intr().)
		 */
		last = NULL;
		for (inp = udb.inp_next; inp != &udb; inp = inp->inp_next) {
			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;

				if ((n = m_copy(m, 0, M_COPYALL)) != NULL) {
					if (sbappendaddr(&last->so_rcv,
						(struct sockaddr *)&udp_in,
						n, (struct mbuf *)0) == 0) {
						m_freem(n);
						udpstat.udps_fullsock++;
					} else
						sorwakeup(last);
				}
			}
			last = inp->inp_socket;
			/*
			 * 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->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;
		}
		if (sbappendaddr(&last->so_rcv, (struct sockaddr *)&udp_in,
		     m, (struct mbuf *)0) == 0) {
			udpstat.udps_fullsock++;
			goto bad;
		}
		sorwakeup(last);
		return;
	}
	/*
	 * Locate pcb for datagram.
	 */
	inp = udp_last_inpcb;
	if (inp->inp_lport != uh->uh_dport ||
	    inp->inp_fport != uh->uh_sport ||
	    inp->inp_faddr.s_addr != ip->ip_src.s_addr ||
	    inp->inp_laddr.s_addr != ip->ip_dst.s_addr) {
		inp = in_pcblookup(&udb, ip->ip_src, uh->uh_sport,
		    ip->ip_dst, uh->uh_dport, INPLOOKUP_WILDCARD);
		if (inp)
			udp_last_inpcb = inp;
		udpstat.udpps_pcbcachemiss++;
	}
	if (inp == 0) {
		udpstat.udps_noport++;
		if (m->m_flags & (M_BCAST | M_MCAST)) {
			udpstat.udps_noportbcast++;
			goto bad;
		}
		*ip = save_ip;
		ip->ip_len += iphlen;
		icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_PORT, 0, 0);
		return;
	}

	/*
	 * 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) {
		struct mbuf **mp = &opts;

		if (inp->inp_flags & INP_RECVDSTADDR) {
			*mp = udp_saveopt((caddr_t) &ip->ip_dst,
			    sizeof(struct in_addr), IP_RECVDSTADDR);
			if (*mp)
				mp = &(*mp)->m_next;
		}
#ifdef notyet
		/* options were tossed above */
		if (inp->inp_flags & INP_RECVOPTS) {
			*mp = udp_saveopt((caddr_t) opts_deleted_above,
			    sizeof(struct in_addr), IP_RECVOPTS);
			if (*mp)
				mp = &(*mp)->m_next;
		}
		/* ip_srcroute doesn't do what we want here, need to fix */
		if (inp->inp_flags & INP_RECVRETOPTS) {
			*mp = udp_saveopt((caddr_t) ip_srcroute(),
			    sizeof(struct in_addr), IP_RECVRETOPTS);
			if (*mp)
				mp = &(*mp)->m_next;
		}
#endif
	}
	iphlen += sizeof(struct udphdr);
	m->m_len -= iphlen;
	m->m_pkthdr.len -= iphlen;
	m->m_data += iphlen;
	if (sbappendaddr(&inp->inp_socket->so_rcv, (struct sockaddr *)&udp_in,
	    m, opts) == 0) {
		udpstat.udps_fullsock++;
		goto bad;
	}
	sorwakeup(inp->inp_socket);
	return;
bad:
	m_freem(m);
	if (opts)
		m_freem(opts);
}

/*
 * Create a "control" mbuf containing the specified data
 * with the specified type for presentation with a datagram.
 */
struct mbuf *
udp_saveopt(p, size, type)