slirp/udp.c - emulators/simh - Rivoreo Source Code Repositories

 /*
  * 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. 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"

 static uint8_t udp_tos(struct socket *so);

 void
 udp_init(Slirp *slirp)
 {
     slirp->udb.so_next = slirp->udb.so_prev = &slirp->udb;
     slirp->udp_last_so = &slirp->udb;
 }

 void udp_cleanup(Slirp *slirp)
 {
     while (slirp->udb.so_next != &slirp->udb) {
         udp_detach(slirp->udb.so_next);
     }
 }

 /* m->m_data  points at ip packet header
  * m->m_len   length ip packet
  * ip->ip_len length data (IPDU)
  */
 void
 udp_input(register struct mbuf *m, int iphlen)
 {
 	Slirp *slirp = m->slirp;
 	register struct ip *ip;
 	register struct udphdr *uh;
 	int len;
 	struct ip save_ip;
 	struct socket *so;

 	DEBUG_CALL("udp_input");
 	DEBUG_ARG("m = %lx", (long)m);
 	DEBUG_ARG("iphlen = %d", iphlen);

 	/*
 	 * 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((uint16_t)uh->uh_ulen);

 	if (ip->ip_len != len) {
 		if (len > ip->ip_len) {
 			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 (uh->uh_sum) {
       memset(&((struct ipovly *)ip)->ih_mbuf, 0, sizeof(struct mbuf_ptr));
 	  ((struct ipovly *)ip)->ih_x1 = 0;
 	  ((struct ipovly *)ip)->ih_len = uh->uh_ulen;
 	  if(cksum(m, len + sizeof(struct ip))) {
 	    goto bad;
 	  }
 	}

         /*
          *  handle DHCP/BOOTP
          */
         if (ntohs(uh->uh_dport) == BOOTP_SERVER &&
             (ip->ip_dst.s_addr == slirp->vhost_addr.s_addr ||
              ip->ip_dst.s_addr == 0xffffffff)) {
                 bootp_input(m);
                 goto bad;
             }

         /*
          *  handle TFTP
          */
         if (ntohs(uh->uh_dport) == TFTP_SERVER &&
             ip->ip_dst.s_addr == slirp->vhost_addr.s_addr) {
             tftp_input(m);
             goto bad;
         }

         if (slirp->restricted) {
             goto bad;
         }

 	/*
 	 * Locate pcb for datagram.
 	 */
 	so = slirp->udp_last_so;
 	if (so == &slirp->udb || so->so_lport != uh->uh_sport ||
 	    so->so_laddr.s_addr != ip->ip_src.s_addr) {
 		struct socket *tmp;

 		for (tmp = slirp->udb.so_next; tmp != &slirp->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 == &slirp->udb) {
 		  so = NULL;
 		} else {
 		  slirp->udp_last_so = so;
 		}
 	}

 	if (so == NULL) {
 	  /*
 	   * If there's no socket for this packet,
 	   * create one
 	   */
 	  so = socreate(slirp);
 	  if (!so) {
 	      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
 	   */
 	  so->so_laddr = ip->ip_src;
 	  so->so_lport = uh->uh_sport;

 	  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.
 	   */
 	}

         so->so_faddr = ip->ip_dst; /* XXX */
         so->so_fport = uh->uh_dport; /* XXX */

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

 	/*
 	 * Now we sendto() the packet.
 	 */
 	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_free(m);
 }

 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 *);
     memset(&ui->ui_i.ih_mbuf, 0 , sizeof(struct mbuf_ptr));
 	ui->ui_x1 = 0;
 	ui->ui_pr = IPPROTO_UDP;
 	ui->ui_len = htons(m->m_len - sizeof(struct ip));
 	/* 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 ((ui->ui_sum = cksum(m, m->m_len)) == 0)
 		ui->ui_sum = 0xffff;
 	((struct ip *)ui)->ip_len = m->m_len;

 	((struct ip *)ui)->ip_ttl = IPDEFTTL;
 	((struct ip *)ui)->ip_tos = iptos;

 	error = ip_output(so, m);

 	return (error);
 }

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

 {
     Slirp *slirp = so->slirp;
     struct sockaddr_in saddr, daddr;

     saddr = *addr;
     if ((so->so_faddr.s_addr & slirp->vnetwork_mask.s_addr) ==
         slirp->vnetwork_addr.s_addr) {
         uint32_t inv_mask = ~slirp->vnetwork_mask.s_addr;

         if ((so->so_faddr.s_addr & inv_mask) == inv_mask) {
             saddr.sin_addr = slirp->vhost_addr;
         } else if (addr->sin_addr.s_addr == loopback_addr.s_addr ||
                    so->so_faddr.s_addr != slirp->vhost_addr.s_addr) {
             saddr.sin_addr = so->so_faddr;
         }
     }
     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(struct socket *so)
 {
   if((so->s = qemu_socket(AF_INET,SOCK_DGRAM,0)) != -1) {
     so->so_expire = curtime + SO_EXPIRE;
     insque(so, &so->slirp->udb);
   }
   return(so->s);
 }

 void
 udp_detach(struct socket *so)
 {
 	closesocket(so->s);
 	sofree(so);
 }

 static const struct tos_t udptos[] = {
 	{0, 53, IPTOS_LOWDELAY, 0},			/* DNS */
 	{0, 0, 0, 0}
 };

 static uint8_t
 udp_tos(struct socket *so)
 {
 	int i = 0;

 	while(udptos[i].tos) {
 		if ((udptos[i].fport && ntohs(so->so_fport) == udptos[i].fport) ||
 		    (udptos[i].lport && ntohs(so->so_lport) == udptos[i].lport)) {
 		    	so->so_emu = udptos[i].emu;
 			return udptos[i].tos;
 		}
 		i++;
 	}

 	return 0;
 }

 struct socket *
 udp_listen(Slirp *slirp, uint32_t haddr, u_int hport, uint32_t laddr,
            u_int lport, int flags)
 {
 	struct sockaddr_in addr;
 	struct socket *so;
 	socklen_t addrlen = sizeof(struct sockaddr_in);

 	so = socreate(slirp);
 	if (!so) {
 	    return NULL;
 	}
 	so->s = qemu_socket(AF_INET,SOCK_DGRAM,0);
 	so->so_expire = curtime + SO_EXPIRE;
 	insque(so, &slirp->udb);

 	addr.sin_family = AF_INET;
 	addr.sin_addr.s_addr = haddr;
 	addr.sin_port = hport;

 	if (bind(so->s,(struct sockaddr *)&addr, addrlen) < 0) {
 		udp_detach(so);
 		return NULL;
 	}
 	socket_set_fast_reuse(so->s);

 	getsockname(so->s,(struct sockaddr *)&addr,&addrlen);
 	so->so_fport = addr.sin_port;
 	if (addr.sin_addr.s_addr == 0 ||
 	    addr.sin_addr.s_addr == loopback_addr.s_addr) {
 	   so->so_faddr = slirp->vhost_addr;
 	} else {
 	   so->so_faddr = addr.sin_addr;
 	}
 	so->so_lport = lport;
 	so->so_laddr.s_addr = laddr;
 	if (flags != SS_FACCEPTONCE)
 	   so->so_expire = 0;

 	so->so_state &= SS_PERSISTENT_MASK;
 	so->so_state |= SS_ISFCONNECTED | flags;

 	return so;
 }
	/*
	* 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. 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"

	static uint8_t udp_tos(struct socket *so);

	void
	udp_init(Slirp *slirp)
	{
	slirp->udb.so_next = slirp->udb.so_prev = &slirp->udb;
	slirp->udp_last_so = &slirp->udb;
	}

	void udp_cleanup(Slirp *slirp)
	{
	while (slirp->udb.so_next != &slirp->udb) {
	udp_detach(slirp->udb.so_next);
	}
	}

	/* m->m_data points at ip packet header
	* m->m_len length ip packet
	* ip->ip_len length data (IPDU)
	*/
	void
	udp_input(register struct mbuf *m, int iphlen)
	{
	Slirp *slirp = m->slirp;
	register struct ip *ip;
	register struct udphdr *uh;
	int len;
	struct ip save_ip;
	struct socket *so;

	DEBUG_CALL("udp_input");
	DEBUG_ARG("m = %lx", (long)m);
	DEBUG_ARG("iphlen = %d", iphlen);

	/*
	* 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((uint16_t)uh->uh_ulen);

	if (ip->ip_len != len) {
	if (len > ip->ip_len) {
	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 (uh->uh_sum) {
	memset(&((struct ipovly *)ip)->ih_mbuf, 0, sizeof(struct mbuf_ptr));
	((struct ipovly *)ip)->ih_x1 = 0;
	((struct ipovly *)ip)->ih_len = uh->uh_ulen;
	if(cksum(m, len + sizeof(struct ip))) {
	goto bad;
	}
	}

	/*
	* handle DHCP/BOOTP
	*/
	if (ntohs(uh->uh_dport) == BOOTP_SERVER &&
	(ip->ip_dst.s_addr == slirp->vhost_addr.s_addr \|\|
	ip->ip_dst.s_addr == 0xffffffff)) {
	bootp_input(m);
	goto bad;
	}

	/*
	* handle TFTP
	*/
	if (ntohs(uh->uh_dport) == TFTP_SERVER &&
	ip->ip_dst.s_addr == slirp->vhost_addr.s_addr) {
	tftp_input(m);
	goto bad;
	}

	if (slirp->restricted) {
	goto bad;
	}

	/*
	* Locate pcb for datagram.
	*/
	so = slirp->udp_last_so;
	if (so == &slirp->udb \|\| so->so_lport != uh->uh_sport \|\|
	so->so_laddr.s_addr != ip->ip_src.s_addr) {
	struct socket *tmp;

	for (tmp = slirp->udb.so_next; tmp != &slirp->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 == &slirp->udb) {
	so = NULL;
	} else {
	slirp->udp_last_so = so;
	}
	}

	if (so == NULL) {
	/*
	* If there's no socket for this packet,
	* create one
	*/
	so = socreate(slirp);
	if (!so) {
	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
	*/
	so->so_laddr = ip->ip_src;
	so->so_lport = uh->uh_sport;

	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.
	*/
	}

	so->so_faddr = ip->ip_dst; /* XXX */
	so->so_fport = uh->uh_dport; /* XXX */

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

	/*
	* Now we sendto() the packet.
	*/
	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_free(m);
	}

	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 *);
	memset(&ui->ui_i.ih_mbuf, 0 , sizeof(struct mbuf_ptr));
	ui->ui_x1 = 0;
	ui->ui_pr = IPPROTO_UDP;
	ui->ui_len = htons(m->m_len - sizeof(struct ip));
	/* 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 ((ui->ui_sum = cksum(m, m->m_len)) == 0)
	ui->ui_sum = 0xffff;
	((struct ip *)ui)->ip_len = m->m_len;

	((struct ip *)ui)->ip_ttl = IPDEFTTL;
	((struct ip *)ui)->ip_tos = iptos;

	error = ip_output(so, m);

	return (error);
	}

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

	{
	Slirp *slirp = so->slirp;
	struct sockaddr_in saddr, daddr;

	saddr = *addr;
	if ((so->so_faddr.s_addr & slirp->vnetwork_mask.s_addr) ==
	slirp->vnetwork_addr.s_addr) {
	uint32_t inv_mask = ~slirp->vnetwork_mask.s_addr;

	if ((so->so_faddr.s_addr & inv_mask) == inv_mask) {
	saddr.sin_addr = slirp->vhost_addr;
	} else if (addr->sin_addr.s_addr == loopback_addr.s_addr \|\|
	so->so_faddr.s_addr != slirp->vhost_addr.s_addr) {
	saddr.sin_addr = so->so_faddr;
	}
	}
	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(struct socket *so)
	{
	if((so->s = qemu_socket(AF_INET,SOCK_DGRAM,0)) != -1) {
	so->so_expire = curtime + SO_EXPIRE;
	insque(so, &so->slirp->udb);
	}
	return(so->s);
	}

	void
	udp_detach(struct socket *so)
	{
	closesocket(so->s);
	sofree(so);
	}

	static const struct tos_t udptos[] = {
	{0, 53, IPTOS_LOWDELAY, 0}, /* DNS */
	{0, 0, 0, 0}
	};

	static uint8_t
	udp_tos(struct socket *so)
	{
	int i = 0;

	while(udptos[i].tos) {
	if ((udptos[i].fport && ntohs(so->so_fport) == udptos[i].fport) \|\|
	(udptos[i].lport && ntohs(so->so_lport) == udptos[i].lport)) {
	so->so_emu = udptos[i].emu;
	return udptos[i].tos;
	}
	i++;
	}

	return 0;
	}

	struct socket *
	udp_listen(Slirp *slirp, uint32_t haddr, u_int hport, uint32_t laddr,
	u_int lport, int flags)
	{
	struct sockaddr_in addr;
	struct socket *so;
	socklen_t addrlen = sizeof(struct sockaddr_in);

	so = socreate(slirp);
	if (!so) {
	return NULL;
	}
	so->s = qemu_socket(AF_INET,SOCK_DGRAM,0);
	so->so_expire = curtime + SO_EXPIRE;
	insque(so, &slirp->udb);

	addr.sin_family = AF_INET;
	addr.sin_addr.s_addr = haddr;
	addr.sin_port = hport;

	if (bind(so->s,(struct sockaddr *)&addr, addrlen) < 0) {
	udp_detach(so);
	return NULL;
	}
	socket_set_fast_reuse(so->s);

	getsockname(so->s,(struct sockaddr *)&addr,&addrlen);
	so->so_fport = addr.sin_port;
	if (addr.sin_addr.s_addr == 0 \|\|
	addr.sin_addr.s_addr == loopback_addr.s_addr) {
	so->so_faddr = slirp->vhost_addr;
	} else {
	so->so_faddr = addr.sin_addr;
	}
	so->so_lport = lport;
	so->so_laddr.s_addr = laddr;
	if (flags != SS_FACCEPTONCE)
	so->so_expire = 0;

	so->so_state &= SS_PERSISTENT_MASK;
	so->so_state \|= SS_ISFCONNECTED \| flags;

	return so;
	}