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Annotation of previous_trunk/src/slirp/ip_icmp.c, revision 1.1

1.1     ! root        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: struct icmpstat icmpstat;
        !            37: 
        !            38: /* The message sent when emulating PING */
        !            39: /* Be nice and tell them it's just a psuedo-ping packet */
        !            40: char icmp_ping_msg[] = "This is a psuedo-PING packet used by Slirp to emulate ICMP ECHO-REQUEST packets.\n";
        !            41: 
        !            42: /* list of actions for icmp_error() on RX of an icmp message */
        !            43: static int icmp_flush[19] = {
        !            44: /*  ECHO REPLY (0)  */   0,
        !            45:                         1,
        !            46:                         1,
        !            47: /* DEST UNREACH (3) */   1,
        !            48: /* SOURCE QUENCH (4)*/   1,
        !            49: /* REDIRECT (5) */       1,
        !            50:                         1,
        !            51:                         1,
        !            52: /* ECHO (8) */           0,
        !            53: /* ROUTERADVERT (9) */   1,
        !            54: /* ROUTERSOLICIT (10) */ 1,
        !            55: /* TIME EXCEEDED (11) */ 1,
        !            56: /* PARAMETER PROBLEM (12) */ 1,
        !            57: /* TIMESTAMP (13) */     0,
        !            58: /* TIMESTAMP REPLY (14) */ 0,
        !            59: /* INFO (15) */          0,
        !            60: /* INFO REPLY (16) */    0,
        !            61: /* ADDR MASK (17) */     0,
        !            62: /* ADDR MASK REPLY (18) */ 0 
        !            63: };
        !            64: 
        !            65: /*
        !            66:  * Process a received ICMP message.
        !            67:  */
        !            68: void
        !            69: icmp_input(m, hlen)
        !            70:      struct mbuf *m;
        !            71:      int hlen;
        !            72: {
        !            73:   register struct icmp *icp;
        !            74:   register struct ip *ip=mtod(m, struct ip *);
        !            75:   int icmplen=ip->ip_len;
        !            76:   /* int code; */
        !            77:        
        !            78:   DEBUG_CALL("icmp_input");
        !            79:   DEBUG_ARG("m = %lx", (long )m);
        !            80:   DEBUG_ARG("m_len = %zu", m->m_len);
        !            81: 
        !            82:   icmpstat.icps_received++;
        !            83:        
        !            84:   /*
        !            85:    * Locate icmp structure in mbuf, and check
        !            86:    * that its not corrupted and of at least minimum length.
        !            87:    */
        !            88:   if (icmplen < ICMP_MINLEN) {          /* min 8 bytes payload */
        !            89:     icmpstat.icps_tooshort++;
        !            90:   freeit:
        !            91:     m_freem(m);
        !            92:     goto end_error;
        !            93:   }
        !            94: 
        !            95:   m->m_len -= hlen;
        !            96:   m->m_data += hlen;
        !            97:   icp = mtod(m, struct icmp *);
        !            98:   if (cksum(m, icmplen)) {
        !            99:     icmpstat.icps_checksum++;
        !           100:     goto freeit;
        !           101:   }
        !           102:   m->m_len += hlen;
        !           103:   m->m_data -= hlen;
        !           104:   
        !           105:   /*   icmpstat.icps_inhist[icp->icmp_type]++; */
        !           106:   /* code = icp->icmp_code; */
        !           107: 
        !           108:   DEBUG_ARG("icmp_type = %d", icp->icmp_type);
        !           109:   switch (icp->icmp_type) {
        !           110:   case ICMP_ECHO:
        !           111:     icp->icmp_type = ICMP_ECHOREPLY;
        !           112:     ip->ip_len += hlen;                     /* since ip_input subtracts this */
        !           113:     if (ip->ip_dst.s_addr == alias_addr.s_addr) {
        !           114:       icmp_reflect(m);
        !           115:     } else {
        !           116:       struct socket *so;
        !           117:       struct sockaddr_in addr;
        !           118:       if ((so = socreate()) == NULL) goto freeit;
        !           119:       if(udp_attach(so) == -1) {
        !           120:        DEBUG_MISC((dfd,"icmp_input udp_attach errno = %d-%s\n", 
        !           121:                    errno,strerror(errno)));
        !           122:        sofree(so);
        !           123:        m_free(m);
        !           124:        goto end_error;
        !           125:       }
        !           126:       so->so_m = m;
        !           127:       so->so_faddr = ip->ip_dst;
        !           128:       so->so_fport = htons(7);
        !           129:       so->so_laddr = ip->ip_src;
        !           130:       so->so_lport = htons(9);
        !           131:       so->so_iptos = ip->ip_tos;
        !           132:       so->so_type = IPPROTO_ICMP;
        !           133:       so->so_state = SS_ISFCONNECTED;
        !           134:       
        !           135:       /* Send the packet */
        !           136:       addr.sin_family = AF_INET;
        !           137:       if ((so->so_faddr.s_addr & htonl(0xffffff00)) == special_addr.s_addr) {
        !           138:        /* It's an alias */
        !           139:        switch(ntohl(so->so_faddr.s_addr) & 0xff) {
        !           140:        case CTL_DNS:
        !           141:          addr.sin_addr = dns_addr;
        !           142:          break;
        !           143:        case CTL_ALIAS:
        !           144:        default:
        !           145:          addr.sin_addr = loopback_addr;
        !           146:          break;
        !           147:        }
        !           148:       } else {
        !           149:        addr.sin_addr = so->so_faddr;
        !           150:       }
        !           151:       addr.sin_port = so->so_fport;
        !           152:       if(sendto(so->s, icmp_ping_msg, strlen(icmp_ping_msg), 0,
        !           153:                (struct sockaddr *)&addr, sizeof(addr)) == -1) {
        !           154:        DEBUG_MISC((dfd,"icmp_input udp sendto tx errno = %d-%s\n",
        !           155:                    errno,strerror(errno)));
        !           156:        icmp_error(m, ICMP_UNREACH,ICMP_UNREACH_NET, 0,strerror(errno)); 
        !           157:        udp_detach(so);
        !           158:       }
        !           159:     } /* if ip->ip_dst.s_addr == alias_addr.s_addr */
        !           160:     break;
        !           161:   case ICMP_UNREACH:
        !           162:     /* XXX? report error? close socket? */
        !           163:   case ICMP_TIMXCEED:
        !           164:   case ICMP_PARAMPROB:
        !           165:   case ICMP_SOURCEQUENCH:
        !           166:   case ICMP_TSTAMP:
        !           167:   case ICMP_MASKREQ:
        !           168:   case ICMP_REDIRECT:
        !           169:     icmpstat.icps_notsupp++;
        !           170:     m_freem(m);
        !           171:     break;
        !           172:     
        !           173:   default:
        !           174:     icmpstat.icps_badtype++;
        !           175:     m_freem(m);
        !           176:   } /* swith */
        !           177: 
        !           178: end_error:
        !           179:   /* m is m_free()'d xor put in a socket xor or given to ip_send */
        !           180:   return;
        !           181: }
        !           182: 
        !           183: 
        !           184: /*
        !           185:  *     Send an ICMP message in response to a situation
        !           186:  *
        !           187:  *     RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. MAY send more (we do).
        !           188:  *                     MUST NOT change this header information.
        !           189:  *                     MUST NOT reply to a multicast/broadcast IP address.
        !           190:  *                     MUST NOT reply to a multicast/broadcast MAC address.
        !           191:  *                     MUST reply to only the first fragment.
        !           192:  */
        !           193: /*
        !           194:  * Send ICMP_UNREACH back to the source regarding msrc.
        !           195:  * mbuf *msrc is used as a template, but is NOT m_free()'d.
        !           196:  * It is reported as the bad ip packet.  The header should
        !           197:  * be fully correct and in host byte order.
        !           198:  * ICMP fragmentation is illegal.  All machines must accept 576 bytes in one 
        !           199:  * packet.  The maximum payload is 576-20(ip hdr)-8(icmp hdr)=548
        !           200:  */
        !           201: 
        !           202: #define ICMP_MAXDATALEN (IP_MSS-28)
        !           203: void
        !           204: icmp_error(
        !           205:      struct mbuf *msrc,
        !           206:      u_char type,
        !           207:      u_char code,
        !           208:      int minsize,
        !           209:      const char *message)
        !           210: {
        !           211:   unsigned hlen, shlen, s_ip_len;
        !           212:   register struct ip *ip;
        !           213:   register struct icmp *icp;
        !           214:   register struct mbuf *m;
        !           215: 
        !           216:   DEBUG_CALL("icmp_error");
        !           217:   DEBUG_ARG("msrc = %lx", (long )msrc);
        !           218:   DEBUG_ARG("msrc_len = %zu", msrc->m_len);
        !           219: 
        !           220:   if(type!=ICMP_UNREACH && type!=ICMP_TIMXCEED) goto end_error;
        !           221: 
        !           222:   /* check msrc */
        !           223:   if(!msrc) goto end_error;
        !           224:   ip = mtod(msrc, struct ip *);
        !           225: #if DEBUG  
        !           226:   { char bufa[INET_ADDRSTRLEN], bufb[INET_ADDRSTRLEN];
        !           227:     inet_ntop(AF_INET, &ip->ip_src, bufa, sizeof(bufa));
        !           228:        inet_ntop(AF_INET, &ip->ip_dst, bufb, sizeof(bufb));
        !           229:     DEBUG_MISC((dfd, " %.16s to %.16s\n", bufa, bufb));
        !           230:   }
        !           231: #endif
        !           232:   if(ip->ip_off & IP_OFFMASK) goto end_error;    /* Only reply to fragment 0 */
        !           233: 
        !           234:   shlen=ip->ip_hl << 2;
        !           235:   s_ip_len=ip->ip_len;
        !           236:   if(ip->ip_p == IPPROTO_ICMP) {
        !           237:     icp = (struct icmp *)((char *)ip + shlen);
        !           238:     /*
        !           239:      * Assume any unknown ICMP type is an error. This isn't
        !           240:      * specified by the RFC, but think about it..
        !           241:      */
        !           242:     if(icp->icmp_type>18 || icmp_flush[icp->icmp_type]) goto end_error;
        !           243:   }
        !           244: 
        !           245:   /* make a copy */
        !           246:   if(!(m=m_get())) goto end_error;               /* get mbuf */
        !           247:   { u_int new_m_size;
        !           248:     new_m_size=sizeof(struct ip )+ICMP_MINLEN+msrc->m_len+ICMP_MAXDATALEN;
        !           249:     if(new_m_size>m->m_size) m_inc(m, new_m_size);
        !           250:   }
        !           251:   memcpy(m->m_data, msrc->m_data, msrc->m_len);
        !           252:   m->m_len = msrc->m_len;                        /* copy msrc to m */
        !           253: 
        !           254:   /* make the header of the reply packet */
        !           255:   ip  = mtod(m, struct ip *);
        !           256:   hlen= sizeof(struct ip );     /* no options in reply */
        !           257:   
        !           258:   /* fill in icmp */
        !           259:   m->m_data += hlen;                  
        !           260:   m->m_len -= hlen;
        !           261: 
        !           262:   icp = mtod(m, struct icmp *);
        !           263: 
        !           264:   if(minsize) s_ip_len=shlen+ICMP_MINLEN;   /* return header+8b only */
        !           265:   else if(s_ip_len>ICMP_MAXDATALEN)         /* maximum size */
        !           266:     s_ip_len=ICMP_MAXDATALEN;
        !           267: 
        !           268:   m->m_len=ICMP_MINLEN+s_ip_len;        /* 8 bytes ICMP header */  
        !           269: 
        !           270:   /* min. size = 8+sizeof(struct ip)+8 */
        !           271: 
        !           272:   icp->icmp_type = type;
        !           273:   icp->icmp_code = code;
        !           274:   icp->icmp_id = 0;
        !           275:   icp->icmp_seq = 0;
        !           276: 
        !           277:   memcpy(&icp->icmp_ip, msrc->m_data, s_ip_len);   /* report the ip packet */
        !           278:   HTONS(icp->icmp_ip.ip_len);
        !           279:   HTONS(icp->icmp_ip.ip_id);
        !           280:   HTONS(icp->icmp_ip.ip_off);
        !           281: 
        !           282: #if DEBUG
        !           283:   if(message) {           /* DEBUG : append message to ICMP packet */
        !           284:     int message_len;
        !           285:     char *cpnt;
        !           286:     message_len=strlen(message);
        !           287:     if(message_len>ICMP_MAXDATALEN) message_len=ICMP_MAXDATALEN;
        !           288:     cpnt=(char *)m->m_data+m->m_len;
        !           289:     memcpy(cpnt, message, message_len);
        !           290:     m->m_len+=message_len;
        !           291:   }
        !           292: #endif
        !           293: 
        !           294:   icp->icmp_cksum = 0;
        !           295:   icp->icmp_cksum = cksum(m, m->m_len);
        !           296: 
        !           297:   m->m_data -= hlen;
        !           298:   m->m_len += hlen;
        !           299: 
        !           300:   /* fill in ip */
        !           301:   ip->ip_hl = hlen >> 2;
        !           302:   ip->ip_len = (u_int16_t)m->m_len;
        !           303:   
        !           304:   ip->ip_tos=((ip->ip_tos & 0x1E) | 0xC0);  /* high priority for errors */
        !           305: 
        !           306:   ip->ip_ttl = MAXTTL;
        !           307:   ip->ip_p = IPPROTO_ICMP;
        !           308:   ip->ip_dst = ip->ip_src;    /* ip adresses */
        !           309:   ip->ip_src = alias_addr;
        !           310: 
        !           311:   (void ) ip_output((struct socket *)NULL, m);
        !           312:   
        !           313:   icmpstat.icps_reflect++;
        !           314: 
        !           315: end_error:
        !           316:   return;
        !           317: }
        !           318: #undef ICMP_MAXDATALEN
        !           319: 
        !           320: /*
        !           321:  * Reflect the ip packet back to the source
        !           322:  */
        !           323: void
        !           324: icmp_reflect(m)
        !           325:      struct mbuf *m;
        !           326: {
        !           327:   register struct ip *ip = mtod(m, struct ip *);
        !           328:   int hlen = ip->ip_hl << 2;
        !           329:   int optlen = hlen - sizeof(struct ip );
        !           330:   register struct icmp *icp;
        !           331: 
        !           332:   /*
        !           333:    * Send an icmp packet back to the ip level,
        !           334:    * after supplying a checksum.
        !           335:    */
        !           336:   m->m_data += hlen;
        !           337:   m->m_len -= hlen;
        !           338:   icp = mtod(m, struct icmp *);
        !           339: 
        !           340:   icp->icmp_cksum = 0;
        !           341:   icp->icmp_cksum = cksum(m, ip->ip_len - hlen);
        !           342: 
        !           343:   m->m_data -= hlen;
        !           344:   m->m_len += hlen;
        !           345: 
        !           346:   /* fill in ip */
        !           347:   if (optlen > 0) {
        !           348:     /*
        !           349:      * Strip out original options by copying rest of first
        !           350:      * mbuf's data back, and adjust the IP length.
        !           351:      */
        !           352:     memmove((caddr_t)(ip + 1), (caddr_t)ip + hlen,
        !           353:            (unsigned )(m->m_len - hlen));
        !           354:     hlen -= optlen;
        !           355:     ip->ip_hl = hlen >> 2;
        !           356:     ip->ip_len -= optlen;
        !           357:     m->m_len -= optlen;
        !           358:   }
        !           359: 
        !           360:   ip->ip_ttl = MAXTTL;
        !           361:   { /* swap */
        !           362:     struct in_addr icmp_dst;
        !           363:     icmp_dst = ip->ip_dst;
        !           364:     ip->ip_dst = ip->ip_src;
        !           365:     ip->ip_src = icmp_dst;
        !           366:   }
        !           367: 
        !           368:   (void ) ip_output((struct socket *)NULL, m);
        !           369: 
        !           370:   icmpstat.icps_reflect++;
        !           371: }

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