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/* |
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* Copyright (c) 1982, 1986, 1988, 1993 |
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* The Regents of the University of California. All rights reserved. |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted provided that the following conditions |
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* are met: |
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* 1. Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* 2. Redistributions in binary form must reproduce the above copyright |
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* notice, this list of conditions and the following disclaimer in the |
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* documentation and/or other materials provided with the distribution. |
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* 3. All advertising materials mentioning features or use of this software |
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* must display the following acknowledgement: |
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* This product includes software developed by the University of |
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* California, Berkeley and its contributors. |
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* 4. Neither the name of the University nor the names of its contributors |
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* may be used to endorse or promote products derived from this software |
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* without specific prior written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
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* SUCH DAMAGE. |
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* |
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* @(#)ip_icmp.c 8.2 (Berkeley) 1/4/94 |
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* ip_icmp.c,v 1.7 1995/05/30 08:09:42 rgrimes Exp |
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*/ |
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|
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#include "slirp.h" |
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#include "ip_icmp.h" |
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|
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struct icmpstat icmpstat; |
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|
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/* The message sent when emulating PING */ |
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/* Be nice and tell them it's just a psuedo-ping packet */ |
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char icmp_ping_msg[] = "This is a psuedo-PING packet used by Slirp to emulate ICMP ECHO-REQUEST packets.\n"; |
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|
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/* list of actions for icmp_error() on RX of an icmp message */ |
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static int icmp_flush[19] = { |
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/* ECHO REPLY (0) */ 0, |
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1, |
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1, |
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/* DEST UNREACH (3) */ 1, |
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/* SOURCE QUENCH (4)*/ 1, |
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/* REDIRECT (5) */ 1, |
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1, |
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1, |
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/* ECHO (8) */ 0, |
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/* ROUTERADVERT (9) */ 1, |
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/* ROUTERSOLICIT (10) */ 1, |
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/* TIME EXCEEDED (11) */ 1, |
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/* PARAMETER PROBLEM (12) */ 1, |
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/* TIMESTAMP (13) */ 0, |
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/* TIMESTAMP REPLY (14) */ 0, |
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/* INFO (15) */ 0, |
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/* INFO REPLY (16) */ 0, |
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/* ADDR MASK (17) */ 0, |
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/* ADDR MASK REPLY (18) */ 0 |
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}; |
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|
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/* |
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* Process a received ICMP message. |
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*/ |
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void |
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icmp_input(m, hlen) |
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struct mbuf *m; |
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int hlen; |
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{ |
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register struct icmp *icp; |
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register struct ip *ip=mtod(m, struct ip *); |
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int icmplen=ip->ip_len; |
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/* int code; */ |
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|
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DEBUG_CALL("icmp_input"); |
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DEBUG_ARG("m = %lx", (long )m); |
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DEBUG_ARG("m_len = %d", m->m_len); |
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|
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icmpstat.icps_received++; |
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|
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/* |
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* Locate icmp structure in mbuf, and check |
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* that its not corrupted and of at least minimum length. |
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*/ |
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if (icmplen < ICMP_MINLEN) { /* min 8 bytes payload */ |
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icmpstat.icps_tooshort++; |
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freeit: |
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m_freem(m); |
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goto end_error; |
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} |
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|
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m->m_len -= hlen; |
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m->m_data += hlen; |
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icp = mtod(m, struct icmp *); |
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if (cksum(m, icmplen)) { |
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icmpstat.icps_checksum++; |
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goto freeit; |
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} |
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m->m_len += hlen; |
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m->m_data -= hlen; |
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|
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/* icmpstat.icps_inhist[icp->icmp_type]++; */ |
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/* code = icp->icmp_code; */ |
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|
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DEBUG_ARG("icmp_type = %d", icp->icmp_type); |
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switch (icp->icmp_type) { |
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case ICMP_ECHO: |
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icp->icmp_type = ICMP_ECHOREPLY; |
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ip->ip_len += hlen; /* since ip_input subtracts this */ |
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if (ip->ip_dst.s_addr == alias_addr.s_addr) { |
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icmp_reflect(m); |
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} else { |
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struct socket *so; |
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struct sockaddr_in addr; |
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if ((so = socreate()) == NULL) goto freeit; |
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if(udp_attach(so) == -1) { |
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DEBUG_MISC((dfd,"icmp_input udp_attach errno = %d-%s\n", |
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errno,strerror(errno))); |
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sofree(so); |
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m_free(m); |
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goto end_error; |
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} |
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so->so_m = m; |
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so->so_faddr = ip->ip_dst; |
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so->so_fport = htons(7); |
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so->so_laddr = ip->ip_src; |
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so->so_lport = htons(9); |
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so->so_iptos = ip->ip_tos; |
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so->so_type = IPPROTO_ICMP; |
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so->so_state = SS_ISFCONNECTED; |
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|
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/* Send the packet */ |
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addr.sin_family = AF_INET; |
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if ((so->so_faddr.s_addr & htonl(0xffffff00)) == special_addr.s_addr) { |
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/* It's an alias */ |
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switch(ntohl(so->so_faddr.s_addr) & 0xff) { |
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case CTL_DNS: |
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addr.sin_addr = dns_addr; |
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break; |
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case CTL_ALIAS: |
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default: |
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addr.sin_addr = loopback_addr; |
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break; |
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} |
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} else { |
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addr.sin_addr = so->so_faddr; |
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} |
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addr.sin_port = so->so_fport; |
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if(sendto(so->s, icmp_ping_msg, strlen(icmp_ping_msg), 0, |
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(struct sockaddr *)&addr, sizeof(addr)) == -1) { |
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DEBUG_MISC((dfd,"icmp_input udp sendto tx errno = %d-%s\n", |
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errno,strerror(errno))); |
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icmp_error(m, ICMP_UNREACH,ICMP_UNREACH_NET, 0,strerror(errno)); |
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udp_detach(so); |
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} |
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} /* if ip->ip_dst.s_addr == alias_addr.s_addr */ |
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break; |
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case ICMP_UNREACH: |
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/* XXX? report error? close socket? */ |
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case ICMP_TIMXCEED: |
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case ICMP_PARAMPROB: |
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case ICMP_SOURCEQUENCH: |
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case ICMP_TSTAMP: |
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case ICMP_MASKREQ: |
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case ICMP_REDIRECT: |
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icmpstat.icps_notsupp++; |
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m_freem(m); |
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break; |
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|
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default: |
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icmpstat.icps_badtype++; |
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m_freem(m); |
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} /* swith */ |
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|
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end_error: |
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/* m is m_free()'d xor put in a socket xor or given to ip_send */ |
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return; |
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} |
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|
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|
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/* |
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* Send an ICMP message in response to a situation |
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* |
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* RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. MAY send more (we do). |
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* MUST NOT change this header information. |
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* MUST NOT reply to a multicast/broadcast IP address. |
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* MUST NOT reply to a multicast/broadcast MAC address. |
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* MUST reply to only the first fragment. |
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*/ |
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/* |
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* Send ICMP_UNREACH back to the source regarding msrc. |
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* mbuf *msrc is used as a template, but is NOT m_free()'d. |
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* It is reported as the bad ip packet. The header should |
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* be fully correct and in host byte order. |
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* ICMP fragmentation is illegal. All machines must accept 576 bytes in one |
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* packet. The maximum payload is 576-20(ip hdr)-8(icmp hdr)=548 |
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*/ |
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|
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#define ICMP_MAXDATALEN (IP_MSS-28) |
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void |
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icmp_error(msrc, type, code, minsize, message) |
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struct mbuf *msrc; |
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u_char type; |
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u_char code; |
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int minsize; |
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char *message; |
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{ |
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unsigned hlen, shlen, s_ip_len; |
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register struct ip *ip; |
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register struct icmp *icp; |
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register struct mbuf *m; |
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|
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DEBUG_CALL("icmp_error"); |
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DEBUG_ARG("msrc = %lx", (long )msrc); |
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DEBUG_ARG("msrc_len = %d", msrc->m_len); |
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|
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if(type!=ICMP_UNREACH && type!=ICMP_TIMXCEED) goto end_error; |
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|
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/* check msrc */ |
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if(!msrc) goto end_error; |
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ip = mtod(msrc, struct ip *); |
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#if DEBUG |
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{ char bufa[20], bufb[20]; |
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strcpy(bufa, inet_ntoa(ip->ip_src)); |
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strcpy(bufb, inet_ntoa(ip->ip_dst)); |
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DEBUG_MISC((dfd, " %.16s to %.16s\n", bufa, bufb)); |
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} |
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#endif |
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if(ip->ip_off & IP_OFFMASK) goto end_error; /* Only reply to fragment 0 */ |
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|
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shlen=ip->ip_hl << 2; |
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s_ip_len=ip->ip_len; |
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if(ip->ip_p == IPPROTO_ICMP) { |
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icp = (struct icmp *)((char *)ip + shlen); |
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/* |
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* Assume any unknown ICMP type is an error. This isn't |
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* specified by the RFC, but think about it.. |
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*/ |
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if(icp->icmp_type>18 || icmp_flush[icp->icmp_type]) goto end_error; |
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} |
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|
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/* make a copy */ |
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if(!(m=m_get())) goto end_error; /* get mbuf */ |
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{ int new_m_size; |
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new_m_size=sizeof(struct ip )+ICMP_MINLEN+msrc->m_len+ICMP_MAXDATALEN; |
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if(new_m_size>m->m_size) m_inc(m, new_m_size); |
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} |
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memcpy(m->m_data, msrc->m_data, msrc->m_len); |
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m->m_len = msrc->m_len; /* copy msrc to m */ |
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|
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/* make the header of the reply packet */ |
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ip = mtod(m, struct ip *); |
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hlen= sizeof(struct ip ); /* no options in reply */ |
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|
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/* fill in icmp */ |
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m->m_data += hlen; |
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m->m_len -= hlen; |
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|
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icp = mtod(m, struct icmp *); |
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|
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if(minsize) s_ip_len=shlen+ICMP_MINLEN; /* return header+8b only */ |
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else if(s_ip_len>ICMP_MAXDATALEN) /* maximum size */ |
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s_ip_len=ICMP_MAXDATALEN; |
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|
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m->m_len=ICMP_MINLEN+s_ip_len; /* 8 bytes ICMP header */ |
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|
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/* min. size = 8+sizeof(struct ip)+8 */ |
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|
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icp->icmp_type = type; |
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icp->icmp_code = code; |
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icp->icmp_id = 0; |
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icp->icmp_seq = 0; |
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|
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memcpy(&icp->icmp_ip, msrc->m_data, s_ip_len); /* report the ip packet */ |
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HTONS(icp->icmp_ip.ip_len); |
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HTONS(icp->icmp_ip.ip_id); |
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HTONS(icp->icmp_ip.ip_off); |
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|
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#if DEBUG |
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if(message) { /* DEBUG : append message to ICMP packet */ |
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int message_len; |
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char *cpnt; |
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message_len=strlen(message); |
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if(message_len>ICMP_MAXDATALEN) message_len=ICMP_MAXDATALEN; |
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cpnt=(char *)m->m_data+m->m_len; |
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memcpy(cpnt, message, message_len); |
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m->m_len+=message_len; |
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} |
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#endif |
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|
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icp->icmp_cksum = 0; |
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icp->icmp_cksum = cksum(m, m->m_len); |
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|
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m->m_data -= hlen; |
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m->m_len += hlen; |
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|
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/* fill in ip */ |
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ip->ip_hl = hlen >> 2; |
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ip->ip_len = m->m_len; |
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|
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ip->ip_tos=((ip->ip_tos & 0x1E) | 0xC0); /* high priority for errors */ |
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|
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ip->ip_ttl = MAXTTL; |
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ip->ip_p = IPPROTO_ICMP; |
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ip->ip_dst = ip->ip_src; /* ip adresses */ |
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ip->ip_src = alias_addr; |
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|
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(void ) ip_output((struct socket *)NULL, m); |
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|
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icmpstat.icps_reflect++; |
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|
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end_error: |
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return; |
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} |
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#undef ICMP_MAXDATALEN |
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|
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/* |
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* Reflect the ip packet back to the source |
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*/ |
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void |
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icmp_reflect(m) |
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struct mbuf *m; |
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{ |
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register struct ip *ip = mtod(m, struct ip *); |
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int hlen = ip->ip_hl << 2; |
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int optlen = hlen - sizeof(struct ip ); |
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register struct icmp *icp; |
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|
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/* |
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* Send an icmp packet back to the ip level, |
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* after supplying a checksum. |
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*/ |
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m->m_data += hlen; |
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m->m_len -= hlen; |
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icp = mtod(m, struct icmp *); |
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|
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icp->icmp_cksum = 0; |
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icp->icmp_cksum = cksum(m, ip->ip_len - hlen); |
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|
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m->m_data -= hlen; |
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m->m_len += hlen; |
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|
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/* fill in ip */ |
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if (optlen > 0) { |
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/* |
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* Strip out original options by copying rest of first |
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* mbuf's data back, and adjust the IP length. |
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*/ |
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memmove((caddr_t)(ip + 1), (caddr_t)ip + hlen, |
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(unsigned )(m->m_len - hlen)); |
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hlen -= optlen; |
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ip->ip_hl = hlen >> 2; |
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ip->ip_len -= optlen; |
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m->m_len -= optlen; |
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} |
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|
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ip->ip_ttl = MAXTTL; |
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{ /* swap */ |
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struct in_addr icmp_dst; |
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icmp_dst = ip->ip_dst; |
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ip->ip_dst = ip->ip_src; |
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ip->ip_src = icmp_dst; |
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} |
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|
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(void ) ip_output((struct socket *)NULL, m); |
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|
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icmpstat.icps_reflect++; |
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} |
