[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. 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.
 *
 *	@(#)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(m, hlen)
     struct mbuf *m;
     int hlen;
{
  register struct icmp *icp;
  register struct ip *ip=mtod(m, struct ip *);
  int icmplen=ip->ip_len;
  /* int code; */

  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;

  /*	icmpstat.icps_inhist[icp->icmp_type]++; */
  /* code = icp->icmp_code; */

  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 == alias_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 & htonl(0xffffff00)) == special_addr.s_addr) {
	/* It's an alias */
	switch(ntohl(so->so_faddr.s_addr) & 0xff) {
	case CTL_DNS:
	  addr.sin_addr = dns_addr;
	  break;
	case CTL_ALIAS:
	default:
	  addr.sin_addr = loopback_addr;
	  break;
	}
      } 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 = alias_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(m)
     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.
	13	* 3. All advertising materials mentioning features or use of this software
	14	* must display the following acknowledgement:
	15	* This product includes software developed by the University of
	16	* California, Berkeley and its contributors.
	17	* 4. Neither the name of the University nor the names of its contributors
	18	* may be used to endorse or promote products derived from this software
	19	* without specific prior written permission.
	20	*
	21	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	22	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	23	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	24	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	25	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	26	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	27	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	28	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	29	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	30	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	31	* SUCH DAMAGE.
	32	*
	33	* @(#)ip_icmp.c 8.2 (Berkeley) 1/4/94
	34	* ip_icmp.c,v 1.7 1995/05/30 08:09:42 rgrimes Exp
	35	*/
	36
	37	#include "slirp.h"
	38	#include "ip_icmp.h"
	39
31a60e22	40	#ifdef LOG_ENABLED
f0cbd3ec	41	struct icmpstat icmpstat;
31a60e22	42	#endif
f0cbd3ec FB	43
f0cbd3ec FB	44	/* The message sent when emulating PING */
7878ff6b	45	/* Be nice and tell them it's just a pseudo-ping packet */
7ca699c8	46	static const char icmp_ping_msg[] = "This is a pseudo-PING packet used by Slirp to emulate ICMP ECHO-REQUEST packets.\n";
f0cbd3ec FB	47
f0cbd3ec FB	48	/* list of actions for icmp_error() on RX of an icmp message */
9634d903	49	static const int icmp_flush[19] = {
f0cbd3ec FB	50	/* ECHO REPLY (0) */ 0,
	51	1,
	52	1,
	53	/* DEST UNREACH (3) */ 1,
	54	/* SOURCE QUENCH (4)*/ 1,
	55	/* REDIRECT (5) */ 1,
	56	1,
	57	1,
	58	/* ECHO (8) */ 0,
	59	/* ROUTERADVERT (9) */ 1,
	60	/* ROUTERSOLICIT (10) */ 1,
	61	/* TIME EXCEEDED (11) */ 1,
	62	/* PARAMETER PROBLEM (12) */ 1,
	63	/* TIMESTAMP (13) */ 0,
	64	/* TIMESTAMP REPLY (14) */ 0,
	65	/* INFO (15) */ 0,
	66	/* INFO REPLY (16) */ 0,
	67	/* ADDR MASK (17) */ 0,
5fafdf24	68	/* ADDR MASK REPLY (18) */ 0
f0cbd3ec FB	69	};
	70
	71	/*
	72	* Process a received ICMP message.
	73	*/
	74	void
	75	icmp_input(m, hlen)
	76	struct mbuf *m;
	77	int hlen;
	78	{
	79	register struct icmp *icp;
	80	register struct ip ip=mtod(m, struct ip );
	81	int icmplen=ip->ip_len;
	82	/* int code; */
5fafdf24	83
f0cbd3ec FB	84	DEBUG_CALL("icmp_input");
	85	DEBUG_ARG("m = %lx", (long )m);
	86	DEBUG_ARG("m_len = %d", m->m_len);
	87
31a60e22	88	STAT(icmpstat.icps_received++);
5fafdf24	89
f0cbd3ec FB	90	/*
	91	* Locate icmp structure in mbuf, and check
	92	* that its not corrupted and of at least minimum length.
	93	*/
	94	if (icmplen < ICMP_MINLEN) { /* min 8 bytes payload */
31a60e22	95	STAT(icmpstat.icps_tooshort++);
f0cbd3ec FB	96	freeit:
	97	m_freem(m);
	98	goto end_error;
	99	}
	100
	101	m->m_len -= hlen;
	102	m->m_data += hlen;
	103	icp = mtod(m, struct icmp *);
	104	if (cksum(m, icmplen)) {
31a60e22	105	STAT(icmpstat.icps_checksum++);
f0cbd3ec FB	106	goto freeit;
	107	}
	108	m->m_len += hlen;
	109	m->m_data -= hlen;
3b46e624	110
f0cbd3ec FB	111	/* icmpstat.icps_inhist[icp->icmp_type]++; */
	112	/* code = icp->icmp_code; */
	113
	114	DEBUG_ARG("icmp_type = %d", icp->icmp_type);
	115	switch (icp->icmp_type) {
	116	case ICMP_ECHO:
	117	icp->icmp_type = ICMP_ECHOREPLY;
	118	ip->ip_len += hlen; /* since ip_input subtracts this */
8dbca8dd	119	if (ip->ip_dst.s_addr == alias_addr.s_addr) {
f0cbd3ec FB	120	icmp_reflect(m);
	121	} else {
	122	struct socket *so;
	123	struct sockaddr_in addr;
	124	if ((so = socreate()) == NULL) goto freeit;
	125	if(udp_attach(so) == -1) {
5fafdf24	126	DEBUG_MISC((dfd,"icmp_input udp_attach errno = %d-%s\n",
f0cbd3ec FB	127	errno,strerror(errno)));
	128	sofree(so);
	129	m_free(m);
	130	goto end_error;
	131	}
	132	so->so_m = m;
	133	so->so_faddr = ip->ip_dst;
	134	so->so_fport = htons(7);
	135	so->so_laddr = ip->ip_src;
	136	so->so_lport = htons(9);
	137	so->so_iptos = ip->ip_tos;
	138	so->so_type = IPPROTO_ICMP;
	139	so->so_state = SS_ISFCONNECTED;
3b46e624	140
f0cbd3ec FB	141	/* Send the packet */
	142	addr.sin_family = AF_INET;
	143	if ((so->so_faddr.s_addr & htonl(0xffffff00)) == special_addr.s_addr) {
	144	/* It's an alias */
	145	switch(ntohl(so->so_faddr.s_addr) & 0xff) {
	146	case CTL_DNS:
	147	addr.sin_addr = dns_addr;
	148	break;
	149	case CTL_ALIAS:
	150	default:
	151	addr.sin_addr = loopback_addr;
	152	break;
	153	}
	154	} else {
	155	addr.sin_addr = so->so_faddr;
	156	}
	157	addr.sin_port = so->so_fport;
	158	if(sendto(so->s, icmp_ping_msg, strlen(icmp_ping_msg), 0,
	159	(struct sockaddr *)&addr, sizeof(addr)) == -1) {
	160	DEBUG_MISC((dfd,"icmp_input udp sendto tx errno = %d-%s\n",
	161	errno,strerror(errno)));
5fafdf24	162	icmp_error(m, ICMP_UNREACH,ICMP_UNREACH_NET, 0,strerror(errno));
f0cbd3ec FB	163	udp_detach(so);
f0cbd3ec FB	164	}
8dbca8dd	165	} /* if ip->ip_dst.s_addr == alias_addr.s_addr */
f0cbd3ec FB	166	break;
	167	case ICMP_UNREACH:
	168	/* XXX? report error? close socket? */
	169	case ICMP_TIMXCEED:
	170	case ICMP_PARAMPROB:
	171	case ICMP_SOURCEQUENCH:
	172	case ICMP_TSTAMP:
	173	case ICMP_MASKREQ:
	174	case ICMP_REDIRECT:
31a60e22	175	STAT(icmpstat.icps_notsupp++);
f0cbd3ec FB	176	m_freem(m);
f0cbd3ec FB	177	break;
3b46e624	178
f0cbd3ec	179	default:
31a60e22	180	STAT(icmpstat.icps_badtype++);
f0cbd3ec FB	181	m_freem(m);
	182	} /* swith */
	183
	184	end_error:
	185	/* m is m_free()'d xor put in a socket xor or given to ip_send */
	186	return;
	187	}
	188
	189
	190	/*
	191	* Send an ICMP message in response to a situation
	192	*
	193	* RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. MAY send more (we do).
	194	* MUST NOT change this header information.
	195	* MUST NOT reply to a multicast/broadcast IP address.
	196	* MUST NOT reply to a multicast/broadcast MAC address.
	197	* MUST reply to only the first fragment.
	198	*/
	199	/*
	200	* Send ICMP_UNREACH back to the source regarding msrc.
	201	* mbuf *msrc is used as a template, but is NOT m_free()'d.
	202	* It is reported as the bad ip packet. The header should
	203	* be fully correct and in host byte order.
5fafdf24	204	* ICMP fragmentation is illegal. All machines must accept 576 bytes in one
f0cbd3ec FB	205	* packet. The maximum payload is 576-20(ip hdr)-8(icmp hdr)=548
	206	*/
	207
	208	#define ICMP_MAXDATALEN (IP_MSS-28)
	209	void
7ccfb2eb BS	210	icmp_error(struct mbuf *msrc, u_char type, u_char code, int minsize,
7ccfb2eb BS	211	const char *message)
f0cbd3ec FB	212	{
	213	unsigned hlen, shlen, s_ip_len;
	214	register struct ip *ip;
	215	register struct icmp *icp;
	216	register struct mbuf *m;
	217
	218	DEBUG_CALL("icmp_error");
	219	DEBUG_ARG("msrc = %lx", (long )msrc);
	220	DEBUG_ARG("msrc_len = %d", msrc->m_len);
	221
	222	if(type!=ICMP_UNREACH && type!=ICMP_TIMXCEED) goto end_error;
	223
	224	/* check msrc */
	225	if(!msrc) goto end_error;
	226	ip = mtod(msrc, struct ip *);
eb38c52c	227	#ifdef DEBUG
f0cbd3ec FB	228	{ char bufa[20], bufb[20];
	229	strcpy(bufa, inet_ntoa(ip->ip_src));
	230	strcpy(bufb, inet_ntoa(ip->ip_dst));
	231	DEBUG_MISC((dfd, " %.16s to %.16s\n", bufa, bufb));
	232	}
	233	#endif
	234	if(ip->ip_off & IP_OFFMASK) goto end_error; /* Only reply to fragment 0 */
	235
	236	shlen=ip->ip_hl << 2;
	237	s_ip_len=ip->ip_len;
	238	if(ip->ip_p == IPPROTO_ICMP) {
	239	icp = (struct icmp )((char )ip + shlen);
	240	/*
	241	* Assume any unknown ICMP type is an error. This isn't
	242	* specified by the RFC, but think about it..
	243	*/
	244	if(icp->icmp_type>18 \|\| icmp_flush[icp->icmp_type]) goto end_error;
	245	}
	246
	247	/* make a copy */
	248	if(!(m=m_get())) goto end_error; /* get mbuf */
	249	{ int new_m_size;
	250	new_m_size=sizeof(struct ip )+ICMP_MINLEN+msrc->m_len+ICMP_MAXDATALEN;
	251	if(new_m_size>m->m_size) m_inc(m, new_m_size);
	252	}
	253	memcpy(m->m_data, msrc->m_data, msrc->m_len);
	254	m->m_len = msrc->m_len; /* copy msrc to m */
	255
	256	/* make the header of the reply packet */
	257	ip = mtod(m, struct ip *);
	258	hlen= sizeof(struct ip ); /* no options in reply */
3b46e624	259
f0cbd3ec	260	/* fill in icmp */
3b46e624	261	m->m_data += hlen;
f0cbd3ec FB	262	m->m_len -= hlen;
	263
	264	icp = mtod(m, struct icmp *);
	265
	266	if(minsize) s_ip_len=shlen+ICMP_MINLEN; /* return header+8b only */
	267	else if(s_ip_len>ICMP_MAXDATALEN) /* maximum size */
	268	s_ip_len=ICMP_MAXDATALEN;
	269
3b46e624	270	m->m_len=ICMP_MINLEN+s_ip_len; /* 8 bytes ICMP header */
f0cbd3ec FB	271
	272	/* min. size = 8+sizeof(struct ip)+8 */
	273
	274	icp->icmp_type = type;
	275	icp->icmp_code = code;
	276	icp->icmp_id = 0;
	277	icp->icmp_seq = 0;
	278
	279	memcpy(&icp->icmp_ip, msrc->m_data, s_ip_len); /* report the ip packet */
	280	HTONS(icp->icmp_ip.ip_len);
	281	HTONS(icp->icmp_ip.ip_id);
	282	HTONS(icp->icmp_ip.ip_off);
	283
eb38c52c	284	#ifdef DEBUG
f0cbd3ec FB	285	if(message) { /* DEBUG : append message to ICMP packet */
	286	int message_len;
	287	char *cpnt;
	288	message_len=strlen(message);
	289	if(message_len>ICMP_MAXDATALEN) message_len=ICMP_MAXDATALEN;
	290	cpnt=(char *)m->m_data+m->m_len;
	291	memcpy(cpnt, message, message_len);
	292	m->m_len+=message_len;
	293	}
	294	#endif
	295
	296	icp->icmp_cksum = 0;
	297	icp->icmp_cksum = cksum(m, m->m_len);
	298
	299	m->m_data -= hlen;
	300	m->m_len += hlen;
	301
	302	/* fill in ip */
	303	ip->ip_hl = hlen >> 2;
	304	ip->ip_len = m->m_len;
3b46e624	305
f0cbd3ec FB	306	ip->ip_tos=((ip->ip_tos & 0x1E) \| 0xC0); /* high priority for errors */
	307
	308	ip->ip_ttl = MAXTTL;
	309	ip->ip_p = IPPROTO_ICMP;
	310	ip->ip_dst = ip->ip_src; /* ip adresses */
8dbca8dd	311	ip->ip_src = alias_addr;
f0cbd3ec FB	312
f0cbd3ec FB	313	(void ) ip_output((struct socket *)NULL, m);
3b46e624	314
31a60e22	315	STAT(icmpstat.icps_reflect++);
f0cbd3ec FB	316
	317	end_error:
	318	return;
	319	}
	320	#undef ICMP_MAXDATALEN
	321
	322	/*
	323	* Reflect the ip packet back to the source
	324	*/
	325	void
	326	icmp_reflect(m)
	327	struct mbuf *m;
	328	{
	329	register struct ip ip = mtod(m, struct ip );
	330	int hlen = ip->ip_hl << 2;
	331	int optlen = hlen - sizeof(struct ip );
	332	register struct icmp *icp;
	333
	334	/*
	335	* Send an icmp packet back to the ip level,
	336	* after supplying a checksum.
	337	*/
	338	m->m_data += hlen;
	339	m->m_len -= hlen;
	340	icp = mtod(m, struct icmp *);
	341
	342	icp->icmp_cksum = 0;
	343	icp->icmp_cksum = cksum(m, ip->ip_len - hlen);
	344
	345	m->m_data -= hlen;
	346	m->m_len += hlen;
	347
	348	/* fill in ip */
	349	if (optlen > 0) {
	350	/*
	351	* Strip out original options by copying rest of first
	352	* mbuf's data back, and adjust the IP length.
	353	*/
	354	memmove((caddr_t)(ip + 1), (caddr_t)ip + hlen,
	355	(unsigned )(m->m_len - hlen));
	356	hlen -= optlen;
	357	ip->ip_hl = hlen >> 2;
	358	ip->ip_len -= optlen;
	359	m->m_len -= optlen;
	360	}
	361
	362	ip->ip_ttl = MAXTTL;
	363	{ /* swap */
	364	struct in_addr icmp_dst;
	365	icmp_dst = ip->ip_dst;
	366	ip->ip_dst = ip->ip_src;
	367	ip->ip_src = icmp_dst;
	368	}
	369
	370	(void ) ip_output((struct socket *)NULL, m);
	371
31a60e22	372	STAT(icmpstat.icps_reflect++);
f0cbd3ec	373	}