[qemu.git] / slirp / ip_icmp.c

/*
 * 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
};

/*
 * 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;

  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_freem(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:
    icp->icmp_type = ICMP_ECHOREPLY;
    ip->ip_len += hlen;	             /* since ip_input subtracts this */
    if (ip->ip_dst.s_addr == vhost_addr.s_addr) {
      icmp_reflect(m);
    } else {
      struct socket *so;
      struct sockaddr_in addr;
      if ((so = socreate()) == NULL) goto freeit;
      if(udp_attach(so) == -1) {
	DEBUG_MISC((dfd,"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 & vnetwork_mask.s_addr) ==
          vnetwork_addr.s_addr) {
	/* It's an alias */
	if (so->so_faddr.s_addr == vnameserver_addr.s_addr) {
	  addr.sin_addr = dns_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((dfd,"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_freem(m);
    break;

  default:
    m_freem(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((dfd, " %.16s to %.16s\n", bufa, bufb));
  }
#endif
  if(ip->ip_off & IP_OFFMASK) goto end_error;    /* Only reply to fragment 0 */

  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 */
  if(!(m=m_get())) goto end_error;               /* get mbuf */
  { 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 adresses */
  ip->ip_src = 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_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);
}
Commit	Line	Data
f0cbd3ec FB	1	/*
	2	* Copyright (c) 1982, 1986, 1988, 1993
	3	* The Regents of the University of California. All rights reserved.
	4	*
	5	* Redistribution and use in source and binary forms, with or without
	6	* modification, are permitted provided that the following conditions
	7	* are met:
	8	* 1. Redistributions of source code must retain the above copyright
	9	* notice, this list of conditions and the following disclaimer.
	10	* 2. Redistributions in binary form must reproduce the above copyright
	11	* notice, this list of conditions and the following disclaimer in the
	12	* documentation and/or other materials provided with the distribution.
2f5f8996	13	* 3. Neither the name of the University nor the names of its contributors
f0cbd3ec FB	14	* may be used to endorse or promote products derived from this software
	15	* without specific prior written permission.
	16	*
	17	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	18	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	19	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	20	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	21	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	22	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	23	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	24	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	25	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	26	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	27	* SUCH DAMAGE.
	28	*
	29	* @(#)ip_icmp.c 8.2 (Berkeley) 1/4/94
	30	* ip_icmp.c,v 1.7 1995/05/30 08:09:42 rgrimes Exp
	31	*/
	32
	33	#include "slirp.h"
	34	#include "ip_icmp.h"
	35
f0cbd3ec	36	/* The message sent when emulating PING */
7878ff6b	37	/* Be nice and tell them it's just a pseudo-ping packet */
7ca699c8	38	static const char icmp_ping_msg[] = "This is a pseudo-PING packet used by Slirp to emulate ICMP ECHO-REQUEST packets.\n";
f0cbd3ec FB	39
f0cbd3ec FB	40	/* list of actions for icmp_error() on RX of an icmp message */
9634d903	41	static const int icmp_flush[19] = {
f0cbd3ec FB	42	/* ECHO REPLY (0) */ 0,
	43	1,
	44	1,
	45	/* DEST UNREACH (3) */ 1,
	46	/* SOURCE QUENCH (4)*/ 1,
	47	/* REDIRECT (5) */ 1,
	48	1,
	49	1,
	50	/* ECHO (8) */ 0,
	51	/* ROUTERADVERT (9) */ 1,
	52	/* ROUTERSOLICIT (10) */ 1,
	53	/* TIME EXCEEDED (11) */ 1,
	54	/* PARAMETER PROBLEM (12) */ 1,
	55	/* TIMESTAMP (13) */ 0,
	56	/* TIMESTAMP REPLY (14) */ 0,
	57	/* INFO (15) */ 0,
	58	/* INFO REPLY (16) */ 0,
	59	/* ADDR MASK (17) */ 0,
5fafdf24	60	/* ADDR MASK REPLY (18) */ 0
f0cbd3ec FB	61	};
	62
	63	/*
	64	* Process a received ICMP message.
	65	*/
	66	void
511d2b14	67	icmp_input(struct mbuf *m, int hlen)
f0cbd3ec FB	68	{
	69	register struct icmp *icp;
	70	register struct ip ip=mtod(m, struct ip );
	71	int icmplen=ip->ip_len;
5fafdf24	72
f0cbd3ec FB	73	DEBUG_CALL("icmp_input");
	74	DEBUG_ARG("m = %lx", (long )m);
	75	DEBUG_ARG("m_len = %d", m->m_len);
	76
f0cbd3ec FB	77	/*
	78	* Locate icmp structure in mbuf, and check
	79	* that its not corrupted and of at least minimum length.
	80	*/
	81	if (icmplen < ICMP_MINLEN) { /* min 8 bytes payload */
f0cbd3ec FB	82	freeit:
	83	m_freem(m);
	84	goto end_error;
	85	}
	86
	87	m->m_len -= hlen;
	88	m->m_data += hlen;
	89	icp = mtod(m, struct icmp *);
	90	if (cksum(m, icmplen)) {
f0cbd3ec FB	91	goto freeit;
	92	}
	93	m->m_len += hlen;
	94	m->m_data -= hlen;
3b46e624	95
f0cbd3ec FB	96	DEBUG_ARG("icmp_type = %d", icp->icmp_type);
	97	switch (icp->icmp_type) {
	98	case ICMP_ECHO:
	99	icp->icmp_type = ICMP_ECHOREPLY;
	100	ip->ip_len += hlen; /* since ip_input subtracts this */
a13a4126	101	if (ip->ip_dst.s_addr == vhost_addr.s_addr) {
f0cbd3ec FB	102	icmp_reflect(m);
	103	} else {
	104	struct socket *so;
	105	struct sockaddr_in addr;
	106	if ((so = socreate()) == NULL) goto freeit;
	107	if(udp_attach(so) == -1) {
5fafdf24	108	DEBUG_MISC((dfd,"icmp_input udp_attach errno = %d-%s\n",
f0cbd3ec FB	109	errno,strerror(errno)));
	110	sofree(so);
	111	m_free(m);
	112	goto end_error;
	113	}
	114	so->so_m = m;
	115	so->so_faddr = ip->ip_dst;
	116	so->so_fport = htons(7);
	117	so->so_laddr = ip->ip_src;
	118	so->so_lport = htons(9);
	119	so->so_iptos = ip->ip_tos;
	120	so->so_type = IPPROTO_ICMP;
	121	so->so_state = SS_ISFCONNECTED;
3b46e624	122
f0cbd3ec FB	123	/* Send the packet */
f0cbd3ec FB	124	addr.sin_family = AF_INET;
a13a4126 JK	125	if ((so->so_faddr.s_addr & vnetwork_mask.s_addr) ==
a13a4126 JK	126	vnetwork_addr.s_addr) {
f0cbd3ec	127	/* It's an alias */
a13a4126	128	if (so->so_faddr.s_addr == vnameserver_addr.s_addr) {
f0cbd3ec	129	addr.sin_addr = dns_addr;
a13a4126	130	} else {
f0cbd3ec	131	addr.sin_addr = loopback_addr;
f0cbd3ec FB	132	}
	133	} else {
	134	addr.sin_addr = so->so_faddr;
	135	}
	136	addr.sin_port = so->so_fport;
	137	if(sendto(so->s, icmp_ping_msg, strlen(icmp_ping_msg), 0,
	138	(struct sockaddr *)&addr, sizeof(addr)) == -1) {
	139	DEBUG_MISC((dfd,"icmp_input udp sendto tx errno = %d-%s\n",
	140	errno,strerror(errno)));
5fafdf24	141	icmp_error(m, ICMP_UNREACH,ICMP_UNREACH_NET, 0,strerror(errno));
f0cbd3ec FB	142	udp_detach(so);
f0cbd3ec FB	143	}
8dbca8dd	144	} /* if ip->ip_dst.s_addr == alias_addr.s_addr */
f0cbd3ec FB	145	break;
	146	case ICMP_UNREACH:
	147	/* XXX? report error? close socket? */
	148	case ICMP_TIMXCEED:
	149	case ICMP_PARAMPROB:
	150	case ICMP_SOURCEQUENCH:
	151	case ICMP_TSTAMP:
	152	case ICMP_MASKREQ:
	153	case ICMP_REDIRECT:
f0cbd3ec FB	154	m_freem(m);
f0cbd3ec FB	155	break;
3b46e624	156
f0cbd3ec	157	default:
f0cbd3ec FB	158	m_freem(m);
	159	} /* swith */
	160
	161	end_error:
	162	/* m is m_free()'d xor put in a socket xor or given to ip_send */
	163	return;
	164	}
	165
	166
	167	/*
	168	* Send an ICMP message in response to a situation
	169	*
	170	* RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. MAY send more (we do).
	171	* MUST NOT change this header information.
	172	* MUST NOT reply to a multicast/broadcast IP address.
	173	* MUST NOT reply to a multicast/broadcast MAC address.
	174	* MUST reply to only the first fragment.
	175	*/
	176	/*
	177	* Send ICMP_UNREACH back to the source regarding msrc.
	178	* mbuf *msrc is used as a template, but is NOT m_free()'d.
	179	* It is reported as the bad ip packet. The header should
	180	* be fully correct and in host byte order.
5fafdf24	181	* ICMP fragmentation is illegal. All machines must accept 576 bytes in one
f0cbd3ec FB	182	* packet. The maximum payload is 576-20(ip hdr)-8(icmp hdr)=548
	183	*/
	184
	185	#define ICMP_MAXDATALEN (IP_MSS-28)
	186	void
7ccfb2eb BS	187	icmp_error(struct mbuf *msrc, u_char type, u_char code, int minsize,
7ccfb2eb BS	188	const char *message)
f0cbd3ec FB	189	{
	190	unsigned hlen, shlen, s_ip_len;
	191	register struct ip *ip;
	192	register struct icmp *icp;
	193	register struct mbuf *m;
	194
	195	DEBUG_CALL("icmp_error");
	196	DEBUG_ARG("msrc = %lx", (long )msrc);
	197	DEBUG_ARG("msrc_len = %d", msrc->m_len);
	198
	199	if(type!=ICMP_UNREACH && type!=ICMP_TIMXCEED) goto end_error;
	200
	201	/* check msrc */
	202	if(!msrc) goto end_error;
	203	ip = mtod(msrc, struct ip *);
eb38c52c	204	#ifdef DEBUG
f0cbd3ec FB	205	{ char bufa[20], bufb[20];
	206	strcpy(bufa, inet_ntoa(ip->ip_src));
	207	strcpy(bufb, inet_ntoa(ip->ip_dst));
	208	DEBUG_MISC((dfd, " %.16s to %.16s\n", bufa, bufb));
	209	}
	210	#endif
	211	if(ip->ip_off & IP_OFFMASK) goto end_error; /* Only reply to fragment 0 */
	212
	213	shlen=ip->ip_hl << 2;
	214	s_ip_len=ip->ip_len;
	215	if(ip->ip_p == IPPROTO_ICMP) {
	216	icp = (struct icmp )((char )ip + shlen);
	217	/*
	218	* Assume any unknown ICMP type is an error. This isn't
	219	* specified by the RFC, but think about it..
	220	*/
	221	if(icp->icmp_type>18 \|\| icmp_flush[icp->icmp_type]) goto end_error;
	222	}
	223
	224	/* make a copy */
	225	if(!(m=m_get())) goto end_error; /* get mbuf */
	226	{ int new_m_size;
	227	new_m_size=sizeof(struct ip )+ICMP_MINLEN+msrc->m_len+ICMP_MAXDATALEN;
	228	if(new_m_size>m->m_size) m_inc(m, new_m_size);
	229	}
	230	memcpy(m->m_data, msrc->m_data, msrc->m_len);
	231	m->m_len = msrc->m_len; /* copy msrc to m */
	232
	233	/* make the header of the reply packet */
	234	ip = mtod(m, struct ip *);
	235	hlen= sizeof(struct ip ); /* no options in reply */
3b46e624	236
f0cbd3ec	237	/* fill in icmp */
3b46e624	238	m->m_data += hlen;
f0cbd3ec FB	239	m->m_len -= hlen;
	240
	241	icp = mtod(m, struct icmp *);
	242
	243	if(minsize) s_ip_len=shlen+ICMP_MINLEN; /* return header+8b only */
	244	else if(s_ip_len>ICMP_MAXDATALEN) /* maximum size */
	245	s_ip_len=ICMP_MAXDATALEN;
	246
3b46e624	247	m->m_len=ICMP_MINLEN+s_ip_len; /* 8 bytes ICMP header */
f0cbd3ec FB	248
	249	/* min. size = 8+sizeof(struct ip)+8 */
	250
	251	icp->icmp_type = type;
	252	icp->icmp_code = code;
	253	icp->icmp_id = 0;
	254	icp->icmp_seq = 0;
	255
	256	memcpy(&icp->icmp_ip, msrc->m_data, s_ip_len); /* report the ip packet */
	257	HTONS(icp->icmp_ip.ip_len);
	258	HTONS(icp->icmp_ip.ip_id);
	259	HTONS(icp->icmp_ip.ip_off);
	260
eb38c52c	261	#ifdef DEBUG
f0cbd3ec FB	262	if(message) { /* DEBUG : append message to ICMP packet */
	263	int message_len;
	264	char *cpnt;
	265	message_len=strlen(message);
	266	if(message_len>ICMP_MAXDATALEN) message_len=ICMP_MAXDATALEN;
	267	cpnt=(char *)m->m_data+m->m_len;
	268	memcpy(cpnt, message, message_len);
	269	m->m_len+=message_len;
	270	}
	271	#endif
	272
	273	icp->icmp_cksum = 0;
	274	icp->icmp_cksum = cksum(m, m->m_len);
	275
	276	m->m_data -= hlen;
	277	m->m_len += hlen;
	278
	279	/* fill in ip */
	280	ip->ip_hl = hlen >> 2;
	281	ip->ip_len = m->m_len;
3b46e624	282
f0cbd3ec FB	283	ip->ip_tos=((ip->ip_tos & 0x1E) \| 0xC0); /* high priority for errors */
	284
	285	ip->ip_ttl = MAXTTL;
	286	ip->ip_p = IPPROTO_ICMP;
	287	ip->ip_dst = ip->ip_src; /* ip adresses */
a13a4126	288	ip->ip_src = vhost_addr;
f0cbd3ec FB	289
f0cbd3ec FB	290	(void ) ip_output((struct socket *)NULL, m);
3b46e624	291
f0cbd3ec FB	292	end_error:
	293	return;
	294	}
	295	#undef ICMP_MAXDATALEN
	296
	297	/*
	298	* Reflect the ip packet back to the source
	299	*/
	300	void
511d2b14	301	icmp_reflect(struct mbuf *m)
f0cbd3ec FB	302	{
	303	register struct ip ip = mtod(m, struct ip );
	304	int hlen = ip->ip_hl << 2;
	305	int optlen = hlen - sizeof(struct ip );
	306	register struct icmp *icp;
	307
	308	/*
	309	* Send an icmp packet back to the ip level,
	310	* after supplying a checksum.
	311	*/
	312	m->m_data += hlen;
	313	m->m_len -= hlen;
	314	icp = mtod(m, struct icmp *);
	315
	316	icp->icmp_cksum = 0;
	317	icp->icmp_cksum = cksum(m, ip->ip_len - hlen);
	318
	319	m->m_data -= hlen;
	320	m->m_len += hlen;
	321
	322	/* fill in ip */
	323	if (optlen > 0) {
	324	/*
	325	* Strip out original options by copying rest of first
	326	* mbuf's data back, and adjust the IP length.
	327	*/
	328	memmove((caddr_t)(ip + 1), (caddr_t)ip + hlen,
	329	(unsigned )(m->m_len - hlen));
	330	hlen -= optlen;
	331	ip->ip_hl = hlen >> 2;
	332	ip->ip_len -= optlen;
	333	m->m_len -= optlen;
	334	}
	335
	336	ip->ip_ttl = MAXTTL;
	337	{ /* swap */
	338	struct in_addr icmp_dst;
	339	icmp_dst = ip->ip_dst;
	340	ip->ip_dst = ip->ip_src;
	341	ip->ip_src = icmp_dst;
	342	}
	343
	344	(void ) ip_output((struct socket *)NULL, m);
f0cbd3ec	345	}