File:  [Qemu by Fabrice Bellard] / qemu / slirp / ip_icmp.c
Revision 1.1.1.6 (vendor branch): download - view: text, annotated - select for diffs
Tue Apr 24 17:41:01 2018 UTC (2 years, 1 month ago) by root
Branches: qemu, MAIN
CVS tags: qemu0150, qemu0141, qemu0140, qemu0130, qemu0125, qemu0124, qemu0123, qemu0122, qemu0121, qemu0120, HEAD
qemu 0.12.0

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

unix.superglobalmegacorp.com