[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"

#ifdef LOG_ENABLED
struct icmpstat icmpstat;
#endif

/* 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);

  STAT(icmpstat.icps_received++);

  /*
   * 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 */
    STAT(icmpstat.icps_tooshort++);
  freeit:
    m_freem(m);
    goto end_error;
  }

  m->m_len -= hlen;
  m->m_data += hlen;
  icp = mtod(m, struct icmp *);
  if (cksum(m, icmplen)) {
    STAT(icmpstat.icps_checksum++);
    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:
    STAT(icmpstat.icps_notsupp++);
    m_freem(m);
    break;

  default:
    STAT(icmpstat.icps_badtype++);
    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);

  STAT(icmpstat.icps_reflect++);

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);

  STAT(icmpstat.icps_reflect++);
}
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
31a60e22	36	#ifdef LOG_ENABLED
f0cbd3ec	37	struct icmpstat icmpstat;
31a60e22	38	#endif
f0cbd3ec FB	39
f0cbd3ec FB	40	/* The message sent when emulating PING */
7878ff6b	41	/* Be nice and tell them it's just a pseudo-ping packet */
7ca699c8	42	static const char icmp_ping_msg[] = "This is a pseudo-PING packet used by Slirp to emulate ICMP ECHO-REQUEST packets.\n";
f0cbd3ec FB	43
f0cbd3ec FB	44	/* list of actions for icmp_error() on RX of an icmp message */
9634d903	45	static const int icmp_flush[19] = {
f0cbd3ec FB	46	/* ECHO REPLY (0) */ 0,
	47	1,
	48	1,
	49	/* DEST UNREACH (3) */ 1,
	50	/* SOURCE QUENCH (4)*/ 1,
	51	/* REDIRECT (5) */ 1,
	52	1,
	53	1,
	54	/* ECHO (8) */ 0,
	55	/* ROUTERADVERT (9) */ 1,
	56	/* ROUTERSOLICIT (10) */ 1,
	57	/* TIME EXCEEDED (11) */ 1,
	58	/* PARAMETER PROBLEM (12) */ 1,
	59	/* TIMESTAMP (13) */ 0,
	60	/* TIMESTAMP REPLY (14) */ 0,
	61	/* INFO (15) */ 0,
	62	/* INFO REPLY (16) */ 0,
	63	/* ADDR MASK (17) */ 0,
5fafdf24	64	/* ADDR MASK REPLY (18) */ 0
f0cbd3ec FB	65	};
	66
	67	/*
	68	* Process a received ICMP message.
	69	*/
	70	void
511d2b14	71	icmp_input(struct mbuf *m, int hlen)
f0cbd3ec FB	72	{
	73	register struct icmp *icp;
	74	register struct ip ip=mtod(m, struct ip );
	75	int icmplen=ip->ip_len;
5fafdf24	76
f0cbd3ec FB	77	DEBUG_CALL("icmp_input");
	78	DEBUG_ARG("m = %lx", (long )m);
	79	DEBUG_ARG("m_len = %d", m->m_len);
	80
31a60e22	81	STAT(icmpstat.icps_received++);
5fafdf24	82
f0cbd3ec FB	83	/*
	84	* Locate icmp structure in mbuf, and check
	85	* that its not corrupted and of at least minimum length.
	86	*/
	87	if (icmplen < ICMP_MINLEN) { /* min 8 bytes payload */
31a60e22	88	STAT(icmpstat.icps_tooshort++);
f0cbd3ec FB	89	freeit:
	90	m_freem(m);
	91	goto end_error;
	92	}
	93
	94	m->m_len -= hlen;
	95	m->m_data += hlen;
	96	icp = mtod(m, struct icmp *);
	97	if (cksum(m, icmplen)) {
31a60e22	98	STAT(icmpstat.icps_checksum++);
f0cbd3ec FB	99	goto freeit;
	100	}
	101	m->m_len += hlen;
	102	m->m_data -= hlen;
3b46e624	103
f0cbd3ec FB	104	DEBUG_ARG("icmp_type = %d", icp->icmp_type);
	105	switch (icp->icmp_type) {
	106	case ICMP_ECHO:
	107	icp->icmp_type = ICMP_ECHOREPLY;
	108	ip->ip_len += hlen; /* since ip_input subtracts this */
a13a4126	109	if (ip->ip_dst.s_addr == vhost_addr.s_addr) {
f0cbd3ec FB	110	icmp_reflect(m);
	111	} else {
	112	struct socket *so;
	113	struct sockaddr_in addr;
	114	if ((so = socreate()) == NULL) goto freeit;
	115	if(udp_attach(so) == -1) {
5fafdf24	116	DEBUG_MISC((dfd,"icmp_input udp_attach errno = %d-%s\n",
f0cbd3ec FB	117	errno,strerror(errno)));
	118	sofree(so);
	119	m_free(m);
	120	goto end_error;
	121	}
	122	so->so_m = m;
	123	so->so_faddr = ip->ip_dst;
	124	so->so_fport = htons(7);
	125	so->so_laddr = ip->ip_src;
	126	so->so_lport = htons(9);
	127	so->so_iptos = ip->ip_tos;
	128	so->so_type = IPPROTO_ICMP;
	129	so->so_state = SS_ISFCONNECTED;
3b46e624	130
f0cbd3ec FB	131	/* Send the packet */
f0cbd3ec FB	132	addr.sin_family = AF_INET;
a13a4126 JK	133	if ((so->so_faddr.s_addr & vnetwork_mask.s_addr) ==
a13a4126 JK	134	vnetwork_addr.s_addr) {
f0cbd3ec	135	/* It's an alias */
a13a4126	136	if (so->so_faddr.s_addr == vnameserver_addr.s_addr) {
f0cbd3ec	137	addr.sin_addr = dns_addr;
a13a4126	138	} else {
f0cbd3ec	139	addr.sin_addr = loopback_addr;
f0cbd3ec FB	140	}
	141	} else {
	142	addr.sin_addr = so->so_faddr;
	143	}
	144	addr.sin_port = so->so_fport;
	145	if(sendto(so->s, icmp_ping_msg, strlen(icmp_ping_msg), 0,
	146	(struct sockaddr *)&addr, sizeof(addr)) == -1) {
	147	DEBUG_MISC((dfd,"icmp_input udp sendto tx errno = %d-%s\n",
	148	errno,strerror(errno)));
5fafdf24	149	icmp_error(m, ICMP_UNREACH,ICMP_UNREACH_NET, 0,strerror(errno));
f0cbd3ec FB	150	udp_detach(so);
f0cbd3ec FB	151	}
8dbca8dd	152	} /* if ip->ip_dst.s_addr == alias_addr.s_addr */
f0cbd3ec FB	153	break;
	154	case ICMP_UNREACH:
	155	/* XXX? report error? close socket? */
	156	case ICMP_TIMXCEED:
	157	case ICMP_PARAMPROB:
	158	case ICMP_SOURCEQUENCH:
	159	case ICMP_TSTAMP:
	160	case ICMP_MASKREQ:
	161	case ICMP_REDIRECT:
31a60e22	162	STAT(icmpstat.icps_notsupp++);
f0cbd3ec FB	163	m_freem(m);
f0cbd3ec FB	164	break;
3b46e624	165
f0cbd3ec	166	default:
31a60e22	167	STAT(icmpstat.icps_badtype++);
f0cbd3ec FB	168	m_freem(m);
	169	} /* swith */
	170
	171	end_error:
	172	/* m is m_free()'d xor put in a socket xor or given to ip_send */
	173	return;
	174	}
	175
	176
	177	/*
	178	* Send an ICMP message in response to a situation
	179	*
	180	* RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. MAY send more (we do).
	181	* MUST NOT change this header information.
	182	* MUST NOT reply to a multicast/broadcast IP address.
	183	* MUST NOT reply to a multicast/broadcast MAC address.
	184	* MUST reply to only the first fragment.
	185	*/
	186	/*
	187	* Send ICMP_UNREACH back to the source regarding msrc.
	188	* mbuf *msrc is used as a template, but is NOT m_free()'d.
	189	* It is reported as the bad ip packet. The header should
	190	* be fully correct and in host byte order.
5fafdf24	191	* ICMP fragmentation is illegal. All machines must accept 576 bytes in one
f0cbd3ec FB	192	* packet. The maximum payload is 576-20(ip hdr)-8(icmp hdr)=548
	193	*/
	194
	195	#define ICMP_MAXDATALEN (IP_MSS-28)
	196	void
7ccfb2eb BS	197	icmp_error(struct mbuf *msrc, u_char type, u_char code, int minsize,
7ccfb2eb BS	198	const char *message)
f0cbd3ec FB	199	{
	200	unsigned hlen, shlen, s_ip_len;
	201	register struct ip *ip;
	202	register struct icmp *icp;
	203	register struct mbuf *m;
	204
	205	DEBUG_CALL("icmp_error");
	206	DEBUG_ARG("msrc = %lx", (long )msrc);
	207	DEBUG_ARG("msrc_len = %d", msrc->m_len);
	208
	209	if(type!=ICMP_UNREACH && type!=ICMP_TIMXCEED) goto end_error;
	210
	211	/* check msrc */
	212	if(!msrc) goto end_error;
	213	ip = mtod(msrc, struct ip *);
eb38c52c	214	#ifdef DEBUG
f0cbd3ec FB	215	{ char bufa[20], bufb[20];
	216	strcpy(bufa, inet_ntoa(ip->ip_src));
	217	strcpy(bufb, inet_ntoa(ip->ip_dst));
	218	DEBUG_MISC((dfd, " %.16s to %.16s\n", bufa, bufb));
	219	}
	220	#endif
	221	if(ip->ip_off & IP_OFFMASK) goto end_error; /* Only reply to fragment 0 */
	222
	223	shlen=ip->ip_hl << 2;
	224	s_ip_len=ip->ip_len;
	225	if(ip->ip_p == IPPROTO_ICMP) {
	226	icp = (struct icmp )((char )ip + shlen);
	227	/*
	228	* Assume any unknown ICMP type is an error. This isn't
	229	* specified by the RFC, but think about it..
	230	*/
	231	if(icp->icmp_type>18 \|\| icmp_flush[icp->icmp_type]) goto end_error;
	232	}
	233
	234	/* make a copy */
	235	if(!(m=m_get())) goto end_error; /* get mbuf */
	236	{ int new_m_size;
	237	new_m_size=sizeof(struct ip )+ICMP_MINLEN+msrc->m_len+ICMP_MAXDATALEN;
	238	if(new_m_size>m->m_size) m_inc(m, new_m_size);
	239	}
	240	memcpy(m->m_data, msrc->m_data, msrc->m_len);
	241	m->m_len = msrc->m_len; /* copy msrc to m */
	242
	243	/* make the header of the reply packet */
	244	ip = mtod(m, struct ip *);
	245	hlen= sizeof(struct ip ); /* no options in reply */
3b46e624	246
f0cbd3ec	247	/* fill in icmp */
3b46e624	248	m->m_data += hlen;
f0cbd3ec FB	249	m->m_len -= hlen;
	250
	251	icp = mtod(m, struct icmp *);
	252
	253	if(minsize) s_ip_len=shlen+ICMP_MINLEN; /* return header+8b only */
	254	else if(s_ip_len>ICMP_MAXDATALEN) /* maximum size */
	255	s_ip_len=ICMP_MAXDATALEN;
	256
3b46e624	257	m->m_len=ICMP_MINLEN+s_ip_len; /* 8 bytes ICMP header */
f0cbd3ec FB	258
	259	/* min. size = 8+sizeof(struct ip)+8 */
	260
	261	icp->icmp_type = type;
	262	icp->icmp_code = code;
	263	icp->icmp_id = 0;
	264	icp->icmp_seq = 0;
	265
	266	memcpy(&icp->icmp_ip, msrc->m_data, s_ip_len); /* report the ip packet */
	267	HTONS(icp->icmp_ip.ip_len);
	268	HTONS(icp->icmp_ip.ip_id);
	269	HTONS(icp->icmp_ip.ip_off);
	270
eb38c52c	271	#ifdef DEBUG
f0cbd3ec FB	272	if(message) { /* DEBUG : append message to ICMP packet */
	273	int message_len;
	274	char *cpnt;
	275	message_len=strlen(message);
	276	if(message_len>ICMP_MAXDATALEN) message_len=ICMP_MAXDATALEN;
	277	cpnt=(char *)m->m_data+m->m_len;
	278	memcpy(cpnt, message, message_len);
	279	m->m_len+=message_len;
	280	}
	281	#endif
	282
	283	icp->icmp_cksum = 0;
	284	icp->icmp_cksum = cksum(m, m->m_len);
	285
	286	m->m_data -= hlen;
	287	m->m_len += hlen;
	288
	289	/* fill in ip */
	290	ip->ip_hl = hlen >> 2;
	291	ip->ip_len = m->m_len;
3b46e624	292
f0cbd3ec FB	293	ip->ip_tos=((ip->ip_tos & 0x1E) \| 0xC0); /* high priority for errors */
	294
	295	ip->ip_ttl = MAXTTL;
	296	ip->ip_p = IPPROTO_ICMP;
	297	ip->ip_dst = ip->ip_src; /* ip adresses */
a13a4126	298	ip->ip_src = vhost_addr;
f0cbd3ec FB	299
f0cbd3ec FB	300	(void ) ip_output((struct socket *)NULL, m);
3b46e624	301
31a60e22	302	STAT(icmpstat.icps_reflect++);
f0cbd3ec FB	303
	304	end_error:
	305	return;
	306	}
	307	#undef ICMP_MAXDATALEN
	308
	309	/*
	310	* Reflect the ip packet back to the source
	311	*/
	312	void
511d2b14	313	icmp_reflect(struct mbuf *m)
f0cbd3ec FB	314	{
	315	register struct ip ip = mtod(m, struct ip );
	316	int hlen = ip->ip_hl << 2;
	317	int optlen = hlen - sizeof(struct ip );
	318	register struct icmp *icp;
	319
	320	/*
	321	* Send an icmp packet back to the ip level,
	322	* after supplying a checksum.
	323	*/
	324	m->m_data += hlen;
	325	m->m_len -= hlen;
	326	icp = mtod(m, struct icmp *);
	327
	328	icp->icmp_cksum = 0;
	329	icp->icmp_cksum = cksum(m, ip->ip_len - hlen);
	330
	331	m->m_data -= hlen;
	332	m->m_len += hlen;
	333
	334	/* fill in ip */
	335	if (optlen > 0) {
	336	/*
	337	* Strip out original options by copying rest of first
	338	* mbuf's data back, and adjust the IP length.
	339	*/
	340	memmove((caddr_t)(ip + 1), (caddr_t)ip + hlen,
	341	(unsigned )(m->m_len - hlen));
	342	hlen -= optlen;
	343	ip->ip_hl = hlen >> 2;
	344	ip->ip_len -= optlen;
	345	m->m_len -= optlen;
	346	}
	347
	348	ip->ip_ttl = MAXTTL;
	349	{ /* swap */
	350	struct in_addr icmp_dst;
	351	icmp_dst = ip->ip_dst;
	352	ip->ip_dst = ip->ip_src;
	353	ip->ip_src = icmp_dst;
	354	}
	355
	356	(void ) ip_output((struct socket *)NULL, m);
	357
31a60e22	358	STAT(icmpstat.icps_reflect++);
f0cbd3ec	359	}