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

 /*
  * Copyright (c) 1982, 1986, 1988, 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.
  *
  *	@(#)ip_icmp.c	8.2 (Berkeley) 1/4/94
  * ip_icmp.c,v 1.7 1995/05/30 08:09:42 rgrimes Exp
  */

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

 /* The message sent when emulating PING */
 /* Be nice and tell them it's just a pseudo-ping packet */
 static const char icmp_ping_msg[] = "This is a pseudo-PING packet used by Slirp to emulate ICMP ECHO-REQUEST packets.\n";

 /* list of actions for icmp_error() on RX of an icmp message */
 static const int icmp_flush[19] = {
 /*  ECHO REPLY (0)  */   0,
 		         1,
 		         1,
 /* DEST UNREACH (3) */   1,
 /* SOURCE QUENCH (4)*/   1,
 /* REDIRECT (5) */       1,
 		         1,
 		         1,
 /* ECHO (8) */           0,
 /* ROUTERADVERT (9) */   1,
 /* ROUTERSOLICIT (10) */ 1,
 /* TIME EXCEEDED (11) */ 1,
 /* PARAMETER PROBLEM (12) */ 1,
 /* TIMESTAMP (13) */     0,
 /* TIMESTAMP REPLY (14) */ 0,
 /* INFO (15) */          0,
 /* INFO REPLY (16) */    0,
 /* ADDR MASK (17) */     0,
 /* ADDR MASK REPLY (18) */ 0
 };

 void icmp_init(Slirp *slirp)
 {
     slirp->icmp.so_next = slirp->icmp.so_prev = &slirp->icmp;
     slirp->icmp_last_so = &slirp->icmp;
 }

 void icmp_cleanup(Slirp *slirp)
 {
     while (slirp->icmp.so_next != &slirp->icmp) {
         icmp_detach(slirp->icmp.so_next);
     }
 }

 static int icmp_send(struct socket *so, struct mbuf *m, int hlen)
 {
     struct ip *ip = mtod(m, struct ip *);
     struct sockaddr_in addr;

     so->s = qemu_socket(AF_INET, SOCK_DGRAM, IPPROTO_ICMP);
     if (so->s == -1) {
         return -1;
     }

     so->so_m = m;
     so->so_faddr = ip->ip_dst;
     so->so_laddr = ip->ip_src;
     so->so_iptos = ip->ip_tos;
     so->so_type = IPPROTO_ICMP;
     so->so_state = SS_ISFCONNECTED;
     so->so_expire = curtime + SO_EXPIRE;

     addr.sin_family = AF_INET;
     addr.sin_addr = so->so_faddr;

     insque(so, &so->slirp->icmp);

     if (sendto(so->s, m->m_data + hlen, m->m_len - hlen, 0,
                (struct sockaddr *)&addr, sizeof(addr)) == -1) {
         DEBUG_MISC("icmp_input icmp sendto tx errno = %d-%s\n",
                     errno, strerror(errno));
         icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_NET, 0, strerror(errno));
         icmp_detach(so);
     }

     return 0;
 }

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

 /*
  * Process a received ICMP message.
  */
 void
 icmp_input(struct mbuf *m, int hlen)
 {
   register struct icmp *icp;
   register struct ip *ip=mtod(m, struct ip *);
   int icmplen=ip->ip_len;
   Slirp *slirp = m->slirp;

   DEBUG_CALL("icmp_input");
   DEBUG_ARG("m = %lx", (long )m);
   DEBUG_ARG("m_len = %d", m->m_len);

   /*
    * Locate icmp structure in mbuf, and check
    * that its not corrupted and of at least minimum length.
    */
   if (icmplen < ICMP_MINLEN) {          /* min 8 bytes payload */
   freeit:
     m_free(m);
     goto end_error;
   }

   m->m_len -= hlen;
   m->m_data += hlen;
   icp = mtod(m, struct icmp *);
   if (cksum(m, icmplen)) {
     goto freeit;
   }
   m->m_len += hlen;
   m->m_data -= hlen;

   DEBUG_ARG("icmp_type = %d", icp->icmp_type);
   switch (icp->icmp_type) {
   case ICMP_ECHO:
     ip->ip_len += hlen;	             /* since ip_input subtracts this */
     if (ip->ip_dst.s_addr == slirp->vhost_addr.s_addr) {
       icmp_reflect(m);
     } else if (slirp->restricted) {
         goto freeit;
     } else {
       struct socket *so;
       struct sockaddr_in addr;
       if ((so = socreate(slirp)) == NULL) goto freeit;
       if (icmp_send(so, m, hlen) == 0) {
         return;
       }
       if(udp_attach(so) == -1) {
 	DEBUG_MISC("icmp_input udp_attach errno = %d-%s\n",
 		    errno,strerror(errno));
 	sofree(so);
 	m_free(m);
 	goto end_error;
       }
       so->so_m = m;
       so->so_faddr = ip->ip_dst;
       so->so_fport = htons(7);
       so->so_laddr = ip->ip_src;
       so->so_lport = htons(9);
       so->so_iptos = ip->ip_tos;
       so->so_type = IPPROTO_ICMP;
       so->so_state = SS_ISFCONNECTED;

       /* Send the packet */
       addr.sin_family = AF_INET;
       if ((so->so_faddr.s_addr & slirp->vnetwork_mask.s_addr) ==
           slirp->vnetwork_addr.s_addr) {
 	/* It's an alias */
 	if (so->so_faddr.s_addr == slirp->vnameserver_addr.s_addr) {
 	  if (get_dns_addr(&addr.sin_addr) < 0)
 	    addr.sin_addr = loopback_addr;
 	} else {
 	  addr.sin_addr = loopback_addr;
 	}
       } else {
 	addr.sin_addr = so->so_faddr;
       }
       addr.sin_port = so->so_fport;
       if(sendto(so->s, icmp_ping_msg, strlen(icmp_ping_msg), 0,
 		(struct sockaddr *)&addr, sizeof(addr)) == -1) {
 	DEBUG_MISC("icmp_input udp sendto tx errno = %d-%s\n",
 		    errno,strerror(errno));
 	icmp_error(m, ICMP_UNREACH,ICMP_UNREACH_NET, 0,strerror(errno));
 	udp_detach(so);
       }
     } /* if ip->ip_dst.s_addr == alias_addr.s_addr */
     break;
   case ICMP_UNREACH:
     /* XXX? report error? close socket? */
   case ICMP_TIMXCEED:
   case ICMP_PARAMPROB:
   case ICMP_SOURCEQUENCH:
   case ICMP_TSTAMP:
   case ICMP_MASKREQ:
   case ICMP_REDIRECT:
     m_free(m);
     break;

   default:
     m_free(m);
   } /* swith */

 end_error:
   /* m is m_free()'d xor put in a socket xor or given to ip_send */
   return;
 }


 /*
  *	Send an ICMP message in response to a situation
  *
  *	RFC 1122: 3.2.2	MUST send at least the IP header and 8 bytes of header. MAY send more (we do).
  *			MUST NOT change this header information.
  *			MUST NOT reply to a multicast/broadcast IP address.
  *			MUST NOT reply to a multicast/broadcast MAC address.
  *			MUST reply to only the first fragment.
  */
 /*
  * Send ICMP_UNREACH back to the source regarding msrc.
  * mbuf *msrc is used as a template, but is NOT m_free()'d.
  * It is reported as the bad ip packet.  The header should
  * be fully correct and in host byte order.
  * ICMP fragmentation is illegal.  All machines must accept 576 bytes in one
  * packet.  The maximum payload is 576-20(ip hdr)-8(icmp hdr)=548
  */

 #define ICMP_MAXDATALEN (IP_MSS-28)
 void
 icmp_error(struct mbuf *msrc, u_char type, u_char code, int minsize,
            const char *message)
 {
   unsigned hlen, shlen, s_ip_len;
   register struct ip *ip;
   register struct icmp *icp;
   register struct mbuf *m;

   DEBUG_CALL("icmp_error");
   DEBUG_ARG("msrc = %lx", (long )msrc);
   DEBUG_ARG("msrc_len = %d", msrc->m_len);

   if(type!=ICMP_UNREACH && type!=ICMP_TIMXCEED) goto end_error;

   /* check msrc */
   if(!msrc) goto end_error;
   ip = mtod(msrc, struct ip *);
 #ifdef DEBUG
   { char bufa[20], bufb[20];
     strcpy(bufa, inet_ntoa(ip->ip_src));
     strcpy(bufb, inet_ntoa(ip->ip_dst));
     DEBUG_MISC(" %.16s to %.16s\n", bufa, bufb);
   }
 #endif
   if(ip->ip_off & IP_OFFMASK) goto end_error;    /* Only reply to fragment 0 */

   /* Do not reply to source-only IPs */
   if ((ip->ip_src.s_addr & htonl(~(0xf << 28))) == 0) {
       goto end_error;
   }

   shlen=ip->ip_hl << 2;
   s_ip_len=ip->ip_len;
   if(ip->ip_p == IPPROTO_ICMP) {
     icp = (struct icmp *)((char *)ip + shlen);
     /*
      *	Assume any unknown ICMP type is an error. This isn't
      *	specified by the RFC, but think about it..
      */
     if(icp->icmp_type>18 || icmp_flush[icp->icmp_type]) goto end_error;
   }

   /* make a copy */
   m = m_get(msrc->slirp);
   if (!m) {
       goto end_error;
   }

   { int new_m_size;
     new_m_size=sizeof(struct ip )+ICMP_MINLEN+msrc->m_len+ICMP_MAXDATALEN;
     if(new_m_size>m->m_size) m_inc(m, new_m_size);
   }
   memcpy(m->m_data, msrc->m_data, msrc->m_len);
   m->m_len = msrc->m_len;                        /* copy msrc to m */

   /* make the header of the reply packet */
   ip  = mtod(m, struct ip *);
   hlen= sizeof(struct ip );     /* no options in reply */

   /* fill in icmp */
   m->m_data += hlen;
   m->m_len -= hlen;

   icp = mtod(m, struct icmp *);

   if(minsize) s_ip_len=shlen+ICMP_MINLEN;   /* return header+8b only */
   else if(s_ip_len>ICMP_MAXDATALEN)         /* maximum size */
     s_ip_len=ICMP_MAXDATALEN;

   m->m_len=ICMP_MINLEN+s_ip_len;        /* 8 bytes ICMP header */

   /* min. size = 8+sizeof(struct ip)+8 */

   icp->icmp_type = type;
   icp->icmp_code = code;
   icp->icmp_id = 0;
   icp->icmp_seq = 0;

   memcpy(&icp->icmp_ip, msrc->m_data, s_ip_len);   /* report the ip packet */
   HTONS(icp->icmp_ip.ip_len);
   HTONS(icp->icmp_ip.ip_id);
   HTONS(icp->icmp_ip.ip_off);

 #ifdef DEBUG
   if(message) {           /* DEBUG : append message to ICMP packet */
     int message_len;
     char *cpnt;
     message_len=strlen(message);
     if(message_len>ICMP_MAXDATALEN) message_len=ICMP_MAXDATALEN;
     cpnt=(char *)m->m_data+m->m_len;
     memcpy(cpnt, message, message_len);
     m->m_len+=message_len;
   }
 #endif

   icp->icmp_cksum = 0;
   icp->icmp_cksum = cksum(m, m->m_len);

   m->m_data -= hlen;
   m->m_len += hlen;

   /* fill in ip */
   ip->ip_hl = hlen >> 2;
   ip->ip_len = m->m_len;

   ip->ip_tos=((ip->ip_tos & 0x1E) | 0xC0);  /* high priority for errors */

   ip->ip_ttl = MAXTTL;
   ip->ip_p = IPPROTO_ICMP;
   ip->ip_dst = ip->ip_src;    /* ip addresses */
   ip->ip_src = m->slirp->vhost_addr;

   (void ) ip_output((struct socket *)NULL, m);

 end_error:
   return;
 }
 #undef ICMP_MAXDATALEN

 /*
  * Reflect the ip packet back to the source
  */
 void
 icmp_reflect(struct mbuf *m)
 {
   register struct ip *ip = mtod(m, struct ip *);
   int hlen = ip->ip_hl << 2;
   int optlen = hlen - sizeof(struct ip );
   register struct icmp *icp;

   /*
    * Send an icmp packet back to the ip level,
    * after supplying a checksum.
    */
   m->m_data += hlen;
   m->m_len -= hlen;
   icp = mtod(m, struct icmp *);

   icp->icmp_type = ICMP_ECHOREPLY;
   icp->icmp_cksum = 0;
   icp->icmp_cksum = cksum(m, ip->ip_len - hlen);

   m->m_data -= hlen;
   m->m_len += hlen;

   /* fill in ip */
   if (optlen > 0) {
     /*
      * Strip out original options by copying rest of first
      * mbuf's data back, and adjust the IP length.
      */
     memmove((caddr_t)(ip + 1), (caddr_t)ip + hlen,
 	    (unsigned )(m->m_len - hlen));
     hlen -= optlen;
     ip->ip_hl = hlen >> 2;
     ip->ip_len -= optlen;
     m->m_len -= optlen;
   }

   ip->ip_ttl = MAXTTL;
   { /* swap */
     struct in_addr icmp_dst;
     icmp_dst = ip->ip_dst;
     ip->ip_dst = ip->ip_src;
     ip->ip_src = icmp_dst;
   }

   (void ) ip_output((struct socket *)NULL, m);
 }

 void icmp_receive(struct socket *so)
 {
     struct mbuf *m = so->so_m;
     struct ip *ip = mtod(m, struct ip *);
     int hlen = ip->ip_hl << 2;
     u_char error_code;
     struct icmp *icp;
     int id, len;

     m->m_data += hlen;
     m->m_len -= hlen;
     icp = mtod(m, struct icmp *);

     id = icp->icmp_id;
     len = qemu_recv(so->s, icp, m->m_len, 0);
     icp->icmp_id = id;

     m->m_data -= hlen;
     m->m_len += hlen;

     if (len == -1 || len == 0) {
         if (errno == ENETUNREACH) {
             error_code = ICMP_UNREACH_NET;
         } else {
             error_code = ICMP_UNREACH_HOST;
         }
         DEBUG_MISC(" udp icmp rx errno = %d-%s\n", errno,
                     strerror(errno));
         icmp_error(so->so_m, ICMP_UNREACH, error_code, 0, strerror(errno));
     } else {
         icmp_reflect(so->so_m);
         so->so_m = NULL; /* Don't m_free() it again! */
     }
     icmp_detach(so);
 }
	/*
	* Copyright (c) 1982, 1986, 1988, 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.
	*
	* @(#)ip_icmp.c 8.2 (Berkeley) 1/4/94
	* ip_icmp.c,v 1.7 1995/05/30 08:09:42 rgrimes Exp
	*/

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

	/* The message sent when emulating PING */
	/* Be nice and tell them it's just a pseudo-ping packet */
	static const char icmp_ping_msg[] = "This is a pseudo-PING packet used by Slirp to emulate ICMP ECHO-REQUEST packets.\n";

	/* list of actions for icmp_error() on RX of an icmp message */
	static const int icmp_flush[19] = {
	/* ECHO REPLY (0) */ 0,
	1,
	1,
	/* DEST UNREACH (3) */ 1,
	/* SOURCE QUENCH (4)*/ 1,
	/* REDIRECT (5) */ 1,
	1,
	1,
	/* ECHO (8) */ 0,
	/* ROUTERADVERT (9) */ 1,
	/* ROUTERSOLICIT (10) */ 1,
	/* TIME EXCEEDED (11) */ 1,
	/* PARAMETER PROBLEM (12) */ 1,
	/* TIMESTAMP (13) */ 0,
	/* TIMESTAMP REPLY (14) */ 0,
	/* INFO (15) */ 0,
	/* INFO REPLY (16) */ 0,
	/* ADDR MASK (17) */ 0,
	/* ADDR MASK REPLY (18) */ 0
	};

	void icmp_init(Slirp *slirp)
	{
	slirp->icmp.so_next = slirp->icmp.so_prev = &slirp->icmp;
	slirp->icmp_last_so = &slirp->icmp;
	}

	void icmp_cleanup(Slirp *slirp)
	{
	while (slirp->icmp.so_next != &slirp->icmp) {
	icmp_detach(slirp->icmp.so_next);
	}
	}

	static int icmp_send(struct socket so, struct mbuf m, int hlen)
	{
	struct ip ip = mtod(m, struct ip );
	struct sockaddr_in addr;

	so->s = qemu_socket(AF_INET, SOCK_DGRAM, IPPROTO_ICMP);
	if (so->s == -1) {
	return -1;
	}

	so->so_m = m;
	so->so_faddr = ip->ip_dst;
	so->so_laddr = ip->ip_src;
	so->so_iptos = ip->ip_tos;
	so->so_type = IPPROTO_ICMP;
	so->so_state = SS_ISFCONNECTED;
	so->so_expire = curtime + SO_EXPIRE;

	addr.sin_family = AF_INET;
	addr.sin_addr = so->so_faddr;

	insque(so, &so->slirp->icmp);

	if (sendto(so->s, m->m_data + hlen, m->m_len - hlen, 0,
	(struct sockaddr *)&addr, sizeof(addr)) == -1) {
	DEBUG_MISC("icmp_input icmp sendto tx errno = %d-%s\n",
	errno, strerror(errno));
	icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_NET, 0, strerror(errno));
	icmp_detach(so);
	}

	return 0;
	}

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

	/*
	* Process a received ICMP message.
	*/
	void
	icmp_input(struct mbuf *m, int hlen)
	{
	register struct icmp *icp;
	register struct ip ip=mtod(m, struct ip );
	int icmplen=ip->ip_len;
	Slirp *slirp = m->slirp;

	DEBUG_CALL("icmp_input");
	DEBUG_ARG("m = %lx", (long )m);
	DEBUG_ARG("m_len = %d", m->m_len);

	/*
	* Locate icmp structure in mbuf, and check
	* that its not corrupted and of at least minimum length.
	*/
	if (icmplen < ICMP_MINLEN) { /* min 8 bytes payload */
	freeit:
	m_free(m);
	goto end_error;
	}

	m->m_len -= hlen;
	m->m_data += hlen;
	icp = mtod(m, struct icmp *);
	if (cksum(m, icmplen)) {
	goto freeit;
	}
	m->m_len += hlen;
	m->m_data -= hlen;

	DEBUG_ARG("icmp_type = %d", icp->icmp_type);
	switch (icp->icmp_type) {
	case ICMP_ECHO:
	ip->ip_len += hlen; /* since ip_input subtracts this */
	if (ip->ip_dst.s_addr == slirp->vhost_addr.s_addr) {
	icmp_reflect(m);
	} else if (slirp->restricted) {
	goto freeit;
	} else {
	struct socket *so;
	struct sockaddr_in addr;
	if ((so = socreate(slirp)) == NULL) goto freeit;
	if (icmp_send(so, m, hlen) == 0) {
	return;
	}
	if(udp_attach(so) == -1) {
	DEBUG_MISC("icmp_input udp_attach errno = %d-%s\n",
	errno,strerror(errno));
	sofree(so);
	m_free(m);
	goto end_error;
	}
	so->so_m = m;
	so->so_faddr = ip->ip_dst;
	so->so_fport = htons(7);
	so->so_laddr = ip->ip_src;
	so->so_lport = htons(9);
	so->so_iptos = ip->ip_tos;
	so->so_type = IPPROTO_ICMP;
	so->so_state = SS_ISFCONNECTED;

	/* Send the packet */
	addr.sin_family = AF_INET;
	if ((so->so_faddr.s_addr & slirp->vnetwork_mask.s_addr) ==
	slirp->vnetwork_addr.s_addr) {
	/* It's an alias */
	if (so->so_faddr.s_addr == slirp->vnameserver_addr.s_addr) {
	if (get_dns_addr(&addr.sin_addr) < 0)
	addr.sin_addr = loopback_addr;
	} else {
	addr.sin_addr = loopback_addr;
	}
	} else {
	addr.sin_addr = so->so_faddr;
	}
	addr.sin_port = so->so_fport;
	if(sendto(so->s, icmp_ping_msg, strlen(icmp_ping_msg), 0,
	(struct sockaddr *)&addr, sizeof(addr)) == -1) {
	DEBUG_MISC("icmp_input udp sendto tx errno = %d-%s\n",
	errno,strerror(errno));
	icmp_error(m, ICMP_UNREACH,ICMP_UNREACH_NET, 0,strerror(errno));
	udp_detach(so);
	}
	} /* if ip->ip_dst.s_addr == alias_addr.s_addr */
	break;
	case ICMP_UNREACH:
	/* XXX? report error? close socket? */
	case ICMP_TIMXCEED:
	case ICMP_PARAMPROB:
	case ICMP_SOURCEQUENCH:
	case ICMP_TSTAMP:
	case ICMP_MASKREQ:
	case ICMP_REDIRECT:
	m_free(m);
	break;

	default:
	m_free(m);
	} /* swith */

	end_error:
	/* m is m_free()'d xor put in a socket xor or given to ip_send */
	return;
	}


	/*
	* Send an ICMP message in response to a situation
	*
	* RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. MAY send more (we do).
	* MUST NOT change this header information.
	* MUST NOT reply to a multicast/broadcast IP address.
	* MUST NOT reply to a multicast/broadcast MAC address.
	* MUST reply to only the first fragment.
	*/
	/*
	* Send ICMP_UNREACH back to the source regarding msrc.
	* mbuf *msrc is used as a template, but is NOT m_free()'d.
	* It is reported as the bad ip packet. The header should
	* be fully correct and in host byte order.
	* ICMP fragmentation is illegal. All machines must accept 576 bytes in one
	* packet. The maximum payload is 576-20(ip hdr)-8(icmp hdr)=548
	*/

	#define ICMP_MAXDATALEN (IP_MSS-28)
	void
	icmp_error(struct mbuf *msrc, u_char type, u_char code, int minsize,
	const char *message)
	{
	unsigned hlen, shlen, s_ip_len;
	register struct ip *ip;
	register struct icmp *icp;
	register struct mbuf *m;

	DEBUG_CALL("icmp_error");
	DEBUG_ARG("msrc = %lx", (long )msrc);
	DEBUG_ARG("msrc_len = %d", msrc->m_len);

	if(type!=ICMP_UNREACH && type!=ICMP_TIMXCEED) goto end_error;

	/* check msrc */
	if(!msrc) goto end_error;
	ip = mtod(msrc, struct ip *);
	#ifdef DEBUG
	{ char bufa[20], bufb[20];
	strcpy(bufa, inet_ntoa(ip->ip_src));
	strcpy(bufb, inet_ntoa(ip->ip_dst));
	DEBUG_MISC(" %.16s to %.16s\n", bufa, bufb);
	}
	#endif
	if(ip->ip_off & IP_OFFMASK) goto end_error; /* Only reply to fragment 0 */

	/* Do not reply to source-only IPs */
	if ((ip->ip_src.s_addr & htonl(~(0xf << 28))) == 0) {
	goto end_error;
	}

	shlen=ip->ip_hl << 2;
	s_ip_len=ip->ip_len;
	if(ip->ip_p == IPPROTO_ICMP) {
	icp = (struct icmp )((char )ip + shlen);
	/*
	* Assume any unknown ICMP type is an error. This isn't
	* specified by the RFC, but think about it..
	*/
	if(icp->icmp_type>18 \|\| icmp_flush[icp->icmp_type]) goto end_error;
	}

	/* make a copy */
	m = m_get(msrc->slirp);
	if (!m) {
	goto end_error;
	}

	{ int new_m_size;
	new_m_size=sizeof(struct ip )+ICMP_MINLEN+msrc->m_len+ICMP_MAXDATALEN;
	if(new_m_size>m->m_size) m_inc(m, new_m_size);
	}
	memcpy(m->m_data, msrc->m_data, msrc->m_len);
	m->m_len = msrc->m_len; /* copy msrc to m */

	/* make the header of the reply packet */
	ip = mtod(m, struct ip *);
	hlen= sizeof(struct ip ); /* no options in reply */

	/* fill in icmp */
	m->m_data += hlen;
	m->m_len -= hlen;

	icp = mtod(m, struct icmp *);

	if(minsize) s_ip_len=shlen+ICMP_MINLEN; /* return header+8b only */
	else if(s_ip_len>ICMP_MAXDATALEN) /* maximum size */
	s_ip_len=ICMP_MAXDATALEN;

	m->m_len=ICMP_MINLEN+s_ip_len; /* 8 bytes ICMP header */

	/* min. size = 8+sizeof(struct ip)+8 */

	icp->icmp_type = type;
	icp->icmp_code = code;
	icp->icmp_id = 0;
	icp->icmp_seq = 0;

	memcpy(&icp->icmp_ip, msrc->m_data, s_ip_len); /* report the ip packet */
	HTONS(icp->icmp_ip.ip_len);
	HTONS(icp->icmp_ip.ip_id);
	HTONS(icp->icmp_ip.ip_off);

	#ifdef DEBUG
	if(message) { /* DEBUG : append message to ICMP packet */
	int message_len;
	char *cpnt;
	message_len=strlen(message);
	if(message_len>ICMP_MAXDATALEN) message_len=ICMP_MAXDATALEN;
	cpnt=(char *)m->m_data+m->m_len;
	memcpy(cpnt, message, message_len);
	m->m_len+=message_len;
	}
	#endif

	icp->icmp_cksum = 0;
	icp->icmp_cksum = cksum(m, m->m_len);

	m->m_data -= hlen;
	m->m_len += hlen;

	/* fill in ip */
	ip->ip_hl = hlen >> 2;
	ip->ip_len = m->m_len;

	ip->ip_tos=((ip->ip_tos & 0x1E) \| 0xC0); /* high priority for errors */

	ip->ip_ttl = MAXTTL;
	ip->ip_p = IPPROTO_ICMP;
	ip->ip_dst = ip->ip_src; /* ip addresses */
	ip->ip_src = m->slirp->vhost_addr;

	(void ) ip_output((struct socket *)NULL, m);

	end_error:
	return;
	}
	#undef ICMP_MAXDATALEN

	/*
	* Reflect the ip packet back to the source
	*/
	void
	icmp_reflect(struct mbuf *m)
	{
	register struct ip ip = mtod(m, struct ip );
	int hlen = ip->ip_hl << 2;
	int optlen = hlen - sizeof(struct ip );
	register struct icmp *icp;

	/*
	* Send an icmp packet back to the ip level,
	* after supplying a checksum.
	*/
	m->m_data += hlen;
	m->m_len -= hlen;
	icp = mtod(m, struct icmp *);

	icp->icmp_type = ICMP_ECHOREPLY;
	icp->icmp_cksum = 0;
	icp->icmp_cksum = cksum(m, ip->ip_len - hlen);

	m->m_data -= hlen;
	m->m_len += hlen;

	/* fill in ip */
	if (optlen > 0) {
	/*
	* Strip out original options by copying rest of first
	* mbuf's data back, and adjust the IP length.
	*/
	memmove((caddr_t)(ip + 1), (caddr_t)ip + hlen,
	(unsigned )(m->m_len - hlen));
	hlen -= optlen;
	ip->ip_hl = hlen >> 2;
	ip->ip_len -= optlen;
	m->m_len -= optlen;
	}

	ip->ip_ttl = MAXTTL;
	{ /* swap */
	struct in_addr icmp_dst;
	icmp_dst = ip->ip_dst;
	ip->ip_dst = ip->ip_src;
	ip->ip_src = icmp_dst;
	}

	(void ) ip_output((struct socket *)NULL, m);
	}

	void icmp_receive(struct socket *so)
	{
	struct mbuf *m = so->so_m;
	struct ip ip = mtod(m, struct ip );
	int hlen = ip->ip_hl << 2;
	u_char error_code;
	struct icmp *icp;
	int id, len;

	m->m_data += hlen;
	m->m_len -= hlen;
	icp = mtod(m, struct icmp *);

	id = icp->icmp_id;
	len = qemu_recv(so->s, icp, m->m_len, 0);
	icp->icmp_id = id;

	m->m_data -= hlen;
	m->m_len += hlen;

	if (len == -1 \|\| len == 0) {
	if (errno == ENETUNREACH) {
	error_code = ICMP_UNREACH_NET;
	} else {
	error_code = ICMP_UNREACH_HOST;
	}
	DEBUG_MISC(" udp icmp rx errno = %d-%s\n", errno,
	strerror(errno));
	icmp_error(so->so_m, ICMP_UNREACH, error_code, 0, strerror(errno));
	} else {
	icmp_reflect(so->so_m);
	so->so_m = NULL; /* Don't m_free() it again! */
	}
	icmp_detach(so);
	}