[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"

struct icmpstat icmpstat;

/* The message sent when emulating PING */
/* Be nice and tell them it's just a psuedo-ping packet */
char icmp_ping_msg[] = "This is a psuedo-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 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);

  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 */
    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)) {
    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:
    icmpstat.icps_notsupp++;
    m_freem(m);
    break;
   
  default:
    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(msrc, type, code, minsize, message)
     struct mbuf *msrc;
     u_char type;
     u_char code;
     int minsize;
     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 *);
#if 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);

#if 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);
 
  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);

  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
	40	struct icmpstat icmpstat;
	41
	42	/* The message sent when emulating PING */
	43	/* Be nice and tell them it's just a psuedo-ping packet */
	44	char icmp_ping_msg[] = "This is a psuedo-PING packet used by Slirp to emulate ICMP ECHO-REQUEST packets.\n";
	45
	46	/* list of actions for icmp_error() on RX of an icmp message */
	47	static int icmp_flush[19] = {
	48	/* ECHO REPLY (0) */ 0,
	49	1,
	50	1,
	51	/* DEST UNREACH (3) */ 1,
	52	/* SOURCE QUENCH (4)*/ 1,
	53	/* REDIRECT (5) */ 1,
	54	1,
	55	1,
	56	/* ECHO (8) */ 0,
	57	/* ROUTERADVERT (9) */ 1,
	58	/* ROUTERSOLICIT (10) */ 1,
	59	/* TIME EXCEEDED (11) */ 1,
	60	/* PARAMETER PROBLEM (12) */ 1,
	61	/* TIMESTAMP (13) */ 0,
	62	/* TIMESTAMP REPLY (14) */ 0,
	63	/* INFO (15) */ 0,
	64	/* INFO REPLY (16) */ 0,
65	/* ADDR MASK (17) */ 0,
5fafdf24	66	/* ADDR MASK REPLY (18) */ 0
f0cbd3ec FB	67	};
	68
	69	/*
	70	* Process a received ICMP message.
	71	*/
	72	void
	73	icmp_input(m, hlen)
	74	struct mbuf *m;
	75	int hlen;
	76	{
	77	register struct icmp *icp;
	78	register struct ip ip=mtod(m, struct ip );
	79	int icmplen=ip->ip_len;
	80	/* int code; */
5fafdf24	81
f0cbd3ec FB	82	DEBUG_CALL("icmp_input");
	83	DEBUG_ARG("m = %lx", (long )m);
	84	DEBUG_ARG("m_len = %d", m->m_len);
	85
	86	icmpstat.icps_received++;
5fafdf24	87
f0cbd3ec FB	88	/*
	89	* Locate icmp structure in mbuf, and check
	90	* that its not corrupted and of at least minimum length.
	91	*/
	92	if (icmplen < ICMP_MINLEN) { /* min 8 bytes payload */
	93	icmpstat.icps_tooshort++;
	94	freeit:
	95	m_freem(m);
	96	goto end_error;
	97	}
	98
	99	m->m_len -= hlen;
	100	m->m_data += hlen;
	101	icp = mtod(m, struct icmp *);
	102	if (cksum(m, icmplen)) {
	103	icmpstat.icps_checksum++;
	104	goto freeit;
	105	}
	106	m->m_len += hlen;
	107	m->m_data -= hlen;
5fafdf24	108
f0cbd3ec FB	109	/* icmpstat.icps_inhist[icp->icmp_type]++; */
	110	/* code = icp->icmp_code; */
	111
	112	DEBUG_ARG("icmp_type = %d", icp->icmp_type);
	113	switch (icp->icmp_type) {
	114	case ICMP_ECHO:
	115	icp->icmp_type = ICMP_ECHOREPLY;
	116	ip->ip_len += hlen; /* since ip_input subtracts this */
8dbca8dd	117	if (ip->ip_dst.s_addr == alias_addr.s_addr) {
f0cbd3ec FB	118	icmp_reflect(m);
	119	} else {
	120	struct socket *so;
	121	struct sockaddr_in addr;
	122	if ((so = socreate()) == NULL) goto freeit;
	123	if(udp_attach(so) == -1) {
5fafdf24	124	DEBUG_MISC((dfd,"icmp_input udp_attach errno = %d-%s\n",
f0cbd3ec FB	125	errno,strerror(errno)));
	126	sofree(so);
	127	m_free(m);
	128	goto end_error;
	129	}
	130	so->so_m = m;
	131	so->so_faddr = ip->ip_dst;
	132	so->so_fport = htons(7);
	133	so->so_laddr = ip->ip_src;
	134	so->so_lport = htons(9);
	135	so->so_iptos = ip->ip_tos;
	136	so->so_type = IPPROTO_ICMP;
	137	so->so_state = SS_ISFCONNECTED;
5fafdf24	138
f0cbd3ec FB	139	/* Send the packet */
	140	addr.sin_family = AF_INET;
	141	if ((so->so_faddr.s_addr & htonl(0xffffff00)) == special_addr.s_addr) {
	142	/* It's an alias */
	143	switch(ntohl(so->so_faddr.s_addr) & 0xff) {
	144	case CTL_DNS:
	145	addr.sin_addr = dns_addr;
	146	break;
	147	case CTL_ALIAS:
	148	default:
	149	addr.sin_addr = loopback_addr;
	150	break;
	151	}
	152	} else {
	153	addr.sin_addr = so->so_faddr;
	154	}
	155	addr.sin_port = so->so_fport;
	156	if(sendto(so->s, icmp_ping_msg, strlen(icmp_ping_msg), 0,
	157	(struct sockaddr *)&addr, sizeof(addr)) == -1) {
	158	DEBUG_MISC((dfd,"icmp_input udp sendto tx errno = %d-%s\n",
	159	errno,strerror(errno)));
5fafdf24	160	icmp_error(m, ICMP_UNREACH,ICMP_UNREACH_NET, 0,strerror(errno));
f0cbd3ec FB	161	udp_detach(so);
f0cbd3ec FB	162	}
8dbca8dd	163	} /* if ip->ip_dst.s_addr == alias_addr.s_addr */
f0cbd3ec FB	164	break;
	165	case ICMP_UNREACH:
	166	/* XXX? report error? close socket? */
	167	case ICMP_TIMXCEED:
	168	case ICMP_PARAMPROB:
	169	case ICMP_SOURCEQUENCH:
	170	case ICMP_TSTAMP:
	171	case ICMP_MASKREQ:
	172	case ICMP_REDIRECT:
	173	icmpstat.icps_notsupp++;
	174	m_freem(m);
	175	break;
5fafdf24	176
f0cbd3ec FB	177	default:
	178	icmpstat.icps_badtype++;
	179	m_freem(m);
	180	} /* swith */
	181
	182	end_error:
	183	/* m is m_free()'d xor put in a socket xor or given to ip_send */
	184	return;
	185	}
	186
	187
	188	/*
	189	* Send an ICMP message in response to a situation
	190	*
	191	* RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. MAY send more (we do).
	192	* MUST NOT change this header information.
	193	* MUST NOT reply to a multicast/broadcast IP address.
	194	* MUST NOT reply to a multicast/broadcast MAC address.
	195	* MUST reply to only the first fragment.
	196	*/
	197	/*
	198	* Send ICMP_UNREACH back to the source regarding msrc.
	199	* mbuf *msrc is used as a template, but is NOT m_free()'d.
	200	* It is reported as the bad ip packet. The header should
	201	* be fully correct and in host byte order.
5fafdf24	202	* ICMP fragmentation is illegal. All machines must accept 576 bytes in one
f0cbd3ec FB	203	* packet. The maximum payload is 576-20(ip hdr)-8(icmp hdr)=548
	204	*/
	205
	206	#define ICMP_MAXDATALEN (IP_MSS-28)
	207	void
	208	icmp_error(msrc, type, code, minsize, message)
	209	struct mbuf *msrc;
	210	u_char type;
	211	u_char code;
	212	int minsize;
	213	char *message;
	214	{
	215	unsigned hlen, shlen, s_ip_len;
	216	register struct ip *ip;
	217	register struct icmp *icp;
	218	register struct mbuf *m;
	219
	220	DEBUG_CALL("icmp_error");
	221	DEBUG_ARG("msrc = %lx", (long )msrc);
	222	DEBUG_ARG("msrc_len = %d", msrc->m_len);
	223
	224	if(type!=ICMP_UNREACH && type!=ICMP_TIMXCEED) goto end_error;
	225
	226	/* check msrc */
	227	if(!msrc) goto end_error;
	228	ip = mtod(msrc, struct ip *);
5fafdf24	229	#if DEBUG
f0cbd3ec FB	230	{ char bufa[20], bufb[20];
	231	strcpy(bufa, inet_ntoa(ip->ip_src));
	232	strcpy(bufb, inet_ntoa(ip->ip_dst));
	233	DEBUG_MISC((dfd, " %.16s to %.16s\n", bufa, bufb));
	234	}
	235	#endif
	236	if(ip->ip_off & IP_OFFMASK) goto end_error; /* Only reply to fragment 0 */
	237
	238	shlen=ip->ip_hl << 2;
	239	s_ip_len=ip->ip_len;
	240	if(ip->ip_p == IPPROTO_ICMP) {
	241	icp = (struct icmp )((char )ip + shlen);
	242	/*
	243	* Assume any unknown ICMP type is an error. This isn't
	244	* specified by the RFC, but think about it..
	245	*/
	246	if(icp->icmp_type>18 \|\| icmp_flush[icp->icmp_type]) goto end_error;
	247	}
	248
	249	/* make a copy */
	250	if(!(m=m_get())) goto end_error; /* get mbuf */
	251	{ int new_m_size;
	252	new_m_size=sizeof(struct ip )+ICMP_MINLEN+msrc->m_len+ICMP_MAXDATALEN;
	253	if(new_m_size>m->m_size) m_inc(m, new_m_size);
	254	}
	255	memcpy(m->m_data, msrc->m_data, msrc->m_len);
	256	m->m_len = msrc->m_len; /* copy msrc to m */
	257
	258	/* make the header of the reply packet */
	259	ip = mtod(m, struct ip *);
	260	hlen= sizeof(struct ip ); /* no options in reply */
5fafdf24	261
f0cbd3ec	262	/* fill in icmp */
5fafdf24	263	m->m_data += hlen;
f0cbd3ec FB	264	m->m_len -= hlen;
	265
	266	icp = mtod(m, struct icmp *);
	267
	268	if(minsize) s_ip_len=shlen+ICMP_MINLEN; /* return header+8b only */
	269	else if(s_ip_len>ICMP_MAXDATALEN) /* maximum size */
	270	s_ip_len=ICMP_MAXDATALEN;
	271
5fafdf24	272	m->m_len=ICMP_MINLEN+s_ip_len; /* 8 bytes ICMP header */
f0cbd3ec FB	273
	274	/* min. size = 8+sizeof(struct ip)+8 */
	275
	276	icp->icmp_type = type;
	277	icp->icmp_code = code;
	278	icp->icmp_id = 0;
	279	icp->icmp_seq = 0;
	280
	281	memcpy(&icp->icmp_ip, msrc->m_data, s_ip_len); /* report the ip packet */
	282	HTONS(icp->icmp_ip.ip_len);
	283	HTONS(icp->icmp_ip.ip_id);
	284	HTONS(icp->icmp_ip.ip_off);
	285
	286	#if DEBUG
	287	if(message) { /* DEBUG : append message to ICMP packet */
	288	int message_len;
	289	char *cpnt;
	290	message_len=strlen(message);
	291	if(message_len>ICMP_MAXDATALEN) message_len=ICMP_MAXDATALEN;
	292	cpnt=(char *)m->m_data+m->m_len;
	293	memcpy(cpnt, message, message_len);
	294	m->m_len+=message_len;
	295	}
	296	#endif
	297
	298	icp->icmp_cksum = 0;
	299	icp->icmp_cksum = cksum(m, m->m_len);
	300
	301	m->m_data -= hlen;
	302	m->m_len += hlen;
	303
	304	/* fill in ip */
	305	ip->ip_hl = hlen >> 2;
	306	ip->ip_len = m->m_len;
5fafdf24	307
f0cbd3ec FB	308	ip->ip_tos=((ip->ip_tos & 0x1E) \| 0xC0); /* high priority for errors */
	309
	310	ip->ip_ttl = MAXTTL;
	311	ip->ip_p = IPPROTO_ICMP;
	312	ip->ip_dst = ip->ip_src; /* ip adresses */
8dbca8dd	313	ip->ip_src = alias_addr;
f0cbd3ec FB	314
f0cbd3ec FB	315	(void ) ip_output((struct socket *)NULL, m);
5fafdf24	316
f0cbd3ec FB	317	icmpstat.icps_reflect++;
	318
	319	end_error:
	320	return;
	321	}
	322	#undef ICMP_MAXDATALEN
	323
	324	/*
	325	* Reflect the ip packet back to the source
	326	*/
	327	void
	328	icmp_reflect(m)
	329	struct mbuf *m;
	330	{
	331	register struct ip ip = mtod(m, struct ip );
	332	int hlen = ip->ip_hl << 2;
	333	int optlen = hlen - sizeof(struct ip );
	334	register struct icmp *icp;
	335
	336	/*
	337	* Send an icmp packet back to the ip level,
	338	* after supplying a checksum.
	339	*/
	340	m->m_data += hlen;
	341	m->m_len -= hlen;
	342	icp = mtod(m, struct icmp *);
	343
	344	icp->icmp_cksum = 0;
	345	icp->icmp_cksum = cksum(m, ip->ip_len - hlen);
	346
	347	m->m_data -= hlen;
	348	m->m_len += hlen;
	349
	350	/* fill in ip */
	351	if (optlen > 0) {
	352	/*
	353	* Strip out original options by copying rest of first
	354	* mbuf's data back, and adjust the IP length.
	355	*/
	356	memmove((caddr_t)(ip + 1), (caddr_t)ip + hlen,
	357	(unsigned )(m->m_len - hlen));
	358	hlen -= optlen;
	359	ip->ip_hl = hlen >> 2;
	360	ip->ip_len -= optlen;
	361	m->m_len -= optlen;
	362	}
	363
	364	ip->ip_ttl = MAXTTL;
	365	{ /* swap */
	366	struct in_addr icmp_dst;
	367	icmp_dst = ip->ip_dst;
	368	ip->ip_dst = ip->ip_src;
	369	ip->ip_src = icmp_dst;
	370	}
	371
	372	(void ) ip_output((struct socket *)NULL, m);
	373
	374	icmpstat.icps_reflect++;
	375	}