Annotation of qemu/slirp/ip_icmp.c, revision 1.1.1.6

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.
1.1.1.4   root       13:  * 3. Neither the name of the University nor the names of its contributors
1.1       root       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 */
1.1.1.3   root       37: /* Be nice and tell them it's just a pseudo-ping packet */
1.1.1.4   root       38: static const char icmp_ping_msg[] = "This is a pseudo-PING packet used by Slirp to emulate ICMP ECHO-REQUEST packets.\n";
1.1       root       39: 
                     40: /* list of actions for icmp_error() on RX of an icmp message */
1.1.1.3   root       41: static const int icmp_flush[19] = {
1.1       root       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,
1.1.1.3   root       60: /* ADDR MASK REPLY (18) */ 0
1.1       root       61: };
                     62: 
                     63: /*
                     64:  * Process a received ICMP message.
                     65:  */
                     66: void
1.1.1.5   root       67: icmp_input(struct mbuf *m, int hlen)
1.1       root       68: {
                     69:   register struct icmp *icp;
                     70:   register struct ip *ip=mtod(m, struct ip *);
                     71:   int icmplen=ip->ip_len;
1.1.1.5   root       72:   Slirp *slirp = m->slirp;
1.1.1.3   root       73: 
1.1       root       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;
1.1.1.3   root       96: 
1.1       root       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 */
1.1.1.5   root      102:     if (ip->ip_dst.s_addr == slirp->vhost_addr.s_addr) {
1.1       root      103:       icmp_reflect(m);
                    104:     } else {
                    105:       struct socket *so;
                    106:       struct sockaddr_in addr;
1.1.1.5   root      107:       if ((so = socreate(slirp)) == NULL) goto freeit;
1.1       root      108:       if(udp_attach(so) == -1) {
1.1.1.3   root      109:        DEBUG_MISC((dfd,"icmp_input udp_attach errno = %d-%s\n",
1.1       root      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;
1.1.1.3   root      123: 
1.1       root      124:       /* Send the packet */
                    125:       addr.sin_family = AF_INET;
1.1.1.5   root      126:       if ((so->so_faddr.s_addr & slirp->vnetwork_mask.s_addr) ==
                    127:           slirp->vnetwork_addr.s_addr) {
1.1       root      128:        /* It's an alias */
1.1.1.5   root      129:        if (so->so_faddr.s_addr == slirp->vnameserver_addr.s_addr) {
1.1.1.6 ! root      130:          if (get_dns_addr(&addr.sin_addr) < 0)
        !           131:            addr.sin_addr = loopback_addr;
1.1.1.5   root      132:        } else {
1.1       root      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)));
1.1.1.3   root      143:        icmp_error(m, ICMP_UNREACH,ICMP_UNREACH_NET, 0,strerror(errno));
1.1       root      144:        udp_detach(so);
                    145:       }
1.1.1.2   root      146:     } /* if ip->ip_dst.s_addr == alias_addr.s_addr */
1.1       root      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;
1.1.1.3   root      158: 
1.1       root      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.
1.1.1.3   root      183:  * ICMP fragmentation is illegal.  All machines must accept 576 bytes in one
1.1       root      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
1.1.1.4   root      189: icmp_error(struct mbuf *msrc, u_char type, u_char code, int minsize,
                    190:            const char *message)
1.1       root      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 *);
1.1.1.4   root      206: #ifdef DEBUG
1.1       root      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 */
1.1.1.5   root      227:   m = m_get(msrc->slirp);
                    228:   if (!m) {
                    229:       goto end_error;
                    230:   }
                    231: 
1.1       root      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 */
1.1.1.3   root      242: 
1.1       root      243:   /* fill in icmp */
1.1.1.3   root      244:   m->m_data += hlen;
1.1       root      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: 
1.1.1.3   root      253:   m->m_len=ICMP_MINLEN+s_ip_len;        /* 8 bytes ICMP header */
1.1       root      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: 
1.1.1.4   root      267: #ifdef DEBUG
1.1       root      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;
1.1.1.3   root      288: 
1.1       root      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 */
1.1.1.5   root      294:   ip->ip_src = m->slirp->vhost_addr;
1.1       root      295: 
                    296:   (void ) ip_output((struct socket *)NULL, m);
1.1.1.3   root      297: 
1.1       root      298: end_error:
                    299:   return;
                    300: }
                    301: #undef ICMP_MAXDATALEN
                    302: 
                    303: /*
                    304:  * Reflect the ip packet back to the source
                    305:  */
                    306: void
1.1.1.5   root      307: icmp_reflect(struct mbuf *m)
1.1       root      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: }

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