udp.c

一个Windows下的Linux专用虚拟机

/*
 * 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
 * udp_usrreq.c,v 1.4 1994/10/02 17:48:45 phk Exp
 */

/*
 * Changes and additions relating to SLiRP
 * Copyright (c) 1995 Danny Gasparovski.
 * 
 * Please read the file COPYRIGHT for the 
 * terms and conditions of the copyright.
 */

#include "slirp.h"
#include "ip_icmp.h"

struct udpstat udpstat;

struct socket udb;

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

struct	socket *udp_last_so = &udb;

/* incrase receive buffer (win32 default: 8k) */
static const int max_rcvbuf_size = 32768;

void
udp_init()
{
	udb.so_next = udb.so_prev = &udb;
}

/* m->m_data  points at ip packet header 
 * m->m_len   length ip packet 
 * ip->ip_len length data (IPDU)
 */
void
udp_input(m, iphlen)
	register struct mbuf *m;
	int iphlen;
{
	register struct ip *ip;
	register struct udphdr *uh;
/*	struct mbuf *opts = 0;*/
	int len;
	struct ip save_ip; 
	struct socket *so;
	
	DEBUG_CALL("udp_input");
	DEBUG_ARG("m = %lx", (long)m);
	DEBUG_ARG("iphlen = %d", iphlen);
	
	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 *);
	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_int16_t)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; 
	save_ip.ip_len+= iphlen;         /* tcp_input subtracts this */

	/*
	 * 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;
	  /* keep uh_sum for ICMP reply
	   * uh->uh_sum = cksum(m, len + sizeof (struct ip)); 
	   * if (uh->uh_sum) { 
	   */
	  if(cksum(m, len + sizeof(struct ip))) {
	    udpstat.udps_badsum++;
	    goto bad;
	  }
	}

        /*
         *  handle DHCP/BOOTP
         */
        if (ntohs(uh->uh_dport) == BOOTP_SERVER) {
            bootp_input(m);
            goto bad;
        }

#ifdef EMULATE_TFTP_SERVER
        /*
         *  handle TFTP
         */
        if (ntohs(uh->uh_dport) == TFTP_SERVER) {
            tftp_input(m);
            goto bad;
        }
#endif

	/*
	 * Locate pcb for datagram.
	 */
	so = udp_last_so;
	if (so->so_lport != uh->uh_sport ||
	    so->so_laddr.s_addr != ip->ip_src.s_addr) {
		struct socket *tmp;
		
		for (tmp = udb.so_next; tmp != &udb; tmp = tmp->so_next) {
			if (tmp->so_lport == uh->uh_sport &&
			    tmp->so_laddr.s_addr == ip->ip_src.s_addr) {
				so = tmp;
				break;
			}
		}
		if (tmp == &udb) {
		  so = NULL;
		} else {
		  udpstat.udpps_pcbcachemiss++;
		  udp_last_so = so;
		}
	}
	
	if (so != NULL) {
	  so->so_faddr = ip->ip_dst;
	  so->so_fport = uh->uh_dport;
	} else {
	  /*
	   * If there's no socket for this packet,
	   * create one
	   */
	  if ((so = socreate()) == NULL) goto bad;
	  if(udp_attach(so) == -1) {
	    DEBUG_MISC((dfd," udp_attach errno = %d-%s\n", 
			errno,strerror(errno)));
	    sofree(so);
	    goto bad;
	  }
	  
	  /*
	   * Setup fields
	   */
	  /* udp_last_so = so; */
	  so->so_laddr = ip->ip_src;
	  so->so_lport = uh->uh_sport;
	  so->so_faddr = ip->ip_dst; /* XXX */
	  so->so_fport = uh->uh_dport; /* XXX */
	  
	  if ((so->so_iptos = udp_tos(so)) == 0)
	    so->so_iptos = ip->ip_tos;
	  
	  /*
	   * XXXXX Here, check if it's in udpexec_list,
	   * and if it is, do the fork_exec() etc.
	   */
	}

	iphlen += sizeof(struct udphdr);
	m->m_len -= iphlen;
	m->m_data += iphlen;

	/*
	 * Now we sendto() the packet.
	 */
	if (so->so_emu)
	   udp_emu(so, m);

	if(sosendto(so,m) == -1) {
	  m->m_len += iphlen;
	  m->m_data -= iphlen;
	  *ip=save_ip;
	  DEBUG_MISC((dfd,"udp tx errno = %d-%s\n",errno,strerror(errno)));
	  icmp_error(m, ICMP_UNREACH,ICMP_UNREACH_NET, 0,strerror(errno));  
	}

	m_free(so->so_m);   /* used for ICMP if error on sorecvfrom */

	/* restore the orig mbuf packet */
	m->m_len += iphlen;
	m->m_data -= iphlen;
	*ip=save_ip;
	so->so_m=m;         /* ICMP backup */

	return;
bad:
	m_freem(m);
	/* if (opts) m_freem(opts); */
	return;
}

int udp_output2(struct socket *so, struct mbuf *m, 
                struct sockaddr_in *saddr, struct sockaddr_in *daddr,
                int iptos)
{
	register struct udpiphdr *ui;
	int error = 0;

	DEBUG_CALL("udp_output");
	DEBUG_ARG("so = %lx", (long)so);
	DEBUG_ARG("m = %lx", (long)m);
	DEBUG_ARG("saddr = %lx", (long)saddr->sin_addr.s_addr);
	DEBUG_ARG("daddr = %lx", (long)daddr->sin_addr.s_addr);

	/*
	 * Adjust for header
	 */
	m->m_data -= sizeof(struct udpiphdr);
	m->m_len += sizeof(struct udpiphdr);
	
	/*
	 * Fill in mbuf with extended UDP header
	 * and addresses and length put into network format.
	 */
	ui = mtod(m, struct udpiphdr *);
	ui->ui_next = ui->ui_prev = 0;
	ui->ui_x1 = 0;
	ui->ui_pr = IPPROTO_UDP;
	ui->ui_len = htons(m->m_len - sizeof(struct ip)); /* + sizeof (struct udphdr)); */
	/* XXXXX Check for from-one-location sockets, or from-any-location sockets */
        ui->ui_src = saddr->sin_addr;
	ui->ui_dst = daddr->sin_addr;
	ui->ui_sport = saddr->sin_port;
	ui->ui_dport = daddr->sin_port;
	ui->ui_ulen = ui->ui_len;

	/*
	 * Stuff checksum and output datagram.
	 */
	ui->ui_sum = 0;
	if (udpcksum) {
	    if ((ui->ui_sum = cksum(m, /* sizeof (struct udpiphdr) + */ m->m_len)) == 0)
		ui->ui_sum = 0xffff;
	}
	((struct ip *)ui)->ip_len = m->m_len;

	((struct ip *)ui)->ip_ttl = ip_defttl;
	((struct ip *)ui)->ip_tos = iptos;
	
	udpstat.udps_opackets++;
	
	error = ip_output(so, m);
	
	return (error);
}

int udp_output(struct socket *so, struct mbuf *m, 
               struct sockaddr_in *addr)

{
    struct sockaddr_in saddr, daddr;

    saddr = *addr;
    if ((so->so_faddr.s_addr & htonl(0xffffff00)) == special_addr.s_addr) {
        saddr.sin_addr.s_addr = so->so_faddr.s_addr;
        if ((so->so_faddr.s_addr & htonl(0x000000ff)) == htonl(0xff))
            saddr.sin_addr.s_addr = alias_addr.s_addr;
    }
    daddr.sin_addr = so->so_laddr;
    daddr.sin_port = so->so_lport;
    
    return udp_output2(so, m, &saddr, &daddr, so->so_iptos);
}

int
udp_attach(so)
     struct socket *so;
{
  struct sockaddr_in addr;
	
  if((so->s = socket(AF_INET,SOCK_DGRAM,0)) != -1) {
    /*
     * Here, we bind() the socket.  Although not really needed
     * (sendto() on an unbound socket will bind it), it's done
     * here so that emulation of ytalk etc. don't have to do it
     */
    addr.sin_family = AF_INET;
    addr.sin_port = 0;
    addr.sin_addr.s_addr = INADDR_ANY;
    if(bind(so->s, (struct sockaddr *)&addr, sizeof(addr))<0) {