pcicmp.c

来自「开放源码的编译器open watcom 1.6.0版的源代码」· C语言 代码 · 共 561 行 · 第 1/2 页

  if (block_icmp)   /* application is handling ICMP; not needed */
     return;

  len    = in_GetHdrLen (ip);
  icmp   = (union icmp_pkt*) ((BYTE*)ip + len);
  len    = intel16 (ip->length) - len;
  for_me = (DWORD) (intel(ip->destination) - my_ip_addr) <= multihomes;

  if (!for_me || broadcast)  /* drop broadcast pings.. */
     return;

  if (len < sizeof(icmp->info))
  {
    STAT (icmpstats.icps_tooshort++);
    return;
  }

  if (checksum(icmp,len) != 0xFFFF)
  {
    STAT (icmpstats.icps_checksum++);
    icmp_print (1, _LANG("bad checksum"), ip->source);
    return;
  }

  type    = icmp->unused.type;
  code    = icmp->unused.code;
  orig_ip = &icmp->ip.ip;
  i_orig  = is_local_addr (intel(orig_ip->source));

  if (type == ICMP_MASKREPLY)
  {
    if (!_domask_req)
       return;
    i_orig = TRUE;
  }

  /* !! this needs work
   */
  if (!i_orig &&
      (type != ICMP_ECHOREPLY && type != ICMP_ECHO &&
       type != ICMP_IREQREPLY && type != ICMP_TSTAMP))
  {
    icmp_bogus (ip, type, NULL);
    return;
  }

  switch (type)
  {
    case ICMP_ECHOREPLY:  /* check if we were waiting for it */
         STAT (icmpstats.icps_inhist[ICMP_ECHOREPLY]++);
         ping_hcache = intel (ip->source);
         ping_tcache = set_timeout (1000) - *(DWORD*)&icmp->echo.identifier;
         if (ping_tcache > 0x7FFFFFFFL)
             ping_tcache += 0x1800B0L;
         ping_number = *(DWORD*)(((BYTE*)&icmp->echo.identifier) + 4);
         return;

    case ICMP_UNREACH:
         STAT (icmpstats.icps_inhist[ICMP_UNREACH]++);
         if (code < DIM(icmp_unreach_str))
         {
           icmp_print (1, msg = icmp_unreach_str[code], ip->source);
#if !defined(USE_UDP_ONLY)
           if (orig_ip->proto == TCP_PROTO)
              _tcp_cancel (orig_ip, type, msg, 0);
           else
#endif
           if (orig_ip->proto == UDP_PROTO)
              _udp_cancel (orig_ip, type, msg, 0);
         }
         else
           STAT (icmpstats.icps_badcode++);
         return;

    case ICMP_SOURCEQUENCH:
         STAT (icmpstats.icps_inhist[ICMP_SOURCEQUENCH]++);
#if !defined(USE_UDP_ONLY)
         if (orig_ip->proto == TCP_PROTO)
         {
           icmp_print (1, _LANG("Source Quench"), ip->source);
           _tcp_cancel (orig_ip, type, NULL, 0);
         }
#endif
         return;

    case ICMP_REDIRECT:
         STAT (icmpstats.icps_inhist[ICMP_REDIRECT]++);
         if (code < 4)
         {
           DWORD new_gw = intel (icmp->ip.ipaddr);

           /* Check if new gateway is on our subnet
            */
           if ((new_gw ^ my_ip_addr) & sin_mask)
           {
             char buf[100], adr[20];
             strcpy (buf, ", GW = ");
             strcat (buf, _inet_ntoa(adr,new_gw));
             icmp_bogus (ip, type, buf);
             return;
           }
           icmp_print (1, msg = icmp_redirect_str[code], ip->source);

           switch (orig_ip->proto)
           {
#if !defined(USE_UDP_ONLY)
             case TCP_PROTO:
                  if (do_redirect.tcp)  /* do it to some socket */
                     _tcp_cancel (orig_ip, type, msg, new_gw);
                  break;
#endif
             case UDP_PROTO:
                  if (do_redirect.udp)
                     _udp_cancel (orig_ip, type, msg, new_gw);
                  break;

             case ICMP_PROTO:
                  if (do_redirect.icmp)
                  {
                    _ip_recursion = 1;
                    _arp_register (new_gw, intel(orig_ip->destination), 0);
                    _ip_recursion = 0;
                  }
                  break;

             case IGMP_PROTO:
                  if (do_redirect.igmp)
                  {
                    _ip_recursion = 1;
                    _arp_register (new_gw, intel(orig_ip->destination), 0);
                    _ip_recursion = 0;
                  }
                  break;
           }
         }
         else
           STAT (icmpstats.icps_badcode++);
         return;

    case ICMP_ECHO:
         STAT (icmpstats.icps_inhist[ICMP_ECHO]++);
         icmp_print (2, _LANG("PING requested of us"), ip->source);
         {
           /* Extract eth-address and create Echo reply packet.
            */
           struct _pkt     *pkt;
           union  icmp_pkt *newicmp;

           if (!icmp_chk_src(ip,ICMP_ECHO))
              return;

           pkt     = (struct _pkt*) _eth_formatpacket (MAC_SRC(ip), IP_TYPE);
           newicmp = &pkt->icmp;

           /* Don't let a huge reassembled ICMP-packet kill us.
            */
           len = min (len, mtu - sizeof(*ip));
           memcpy (newicmp, icmp, len);
           newicmp->echo.type = ICMP_ECHOREPLY;
           newicmp->echo.code = code;

           /* Use supplied ip values in case we ever multi-home.
            * Note that ip values are still in network order.
            */
           icmp_send (pkt, ip->destination, ip->source, len);
           icmp_print (2, _LANG("PING reply sent"), 0);
         }
         return;

    case ICMP_TIMXCEED:
         if (code >= DIM(icmp_exceed_str))
         {
           STAT (icmpstats.icps_badcode++);
           return;
         }
         STAT (icmpstats.icps_inhist[ICMP_TIMXCEED]++);

         if (code != 1)
            switch (orig_ip->proto)
            {
#if !defined(USE_UDP_ONLY)
              case TCP_PROTO:
                   icmp_print (1, icmp_exceed_str[code], ip->source);
                   _tcp_cancel (orig_ip, ICMP_TIMXCEED, NULL, 0);
                   break;
#endif
              case UDP_PROTO:
                   icmp_print (1, icmp_exceed_str[code], ip->source);
                   _udp_cancel (orig_ip, ICMP_TIMXCEED, NULL, 0);
                   break;
            }
         return;

    case ICMP_PARAMPROB:
         STAT (icmpstats.icps_inhist[ICMP_PARAMPROB]++);
         switch (orig_ip->proto)
         {
#if !defined(USE_UDP_ONLY)
           case TCP_PROTO:
                icmp_print (0, _LANG(icmp_type_str[type]), ip->source);
                _tcp_cancel (orig_ip, type, NULL, 0);
                break;
#endif
           case UDP_PROTO:
                icmp_print (0, _LANG(icmp_type_str[type]), ip->source);
                _udp_cancel (orig_ip, type, NULL, 0);
                break;
         }
         return;

    case ICMP_ROUTERADVERT:  /* todo !! */
         STAT (icmpstats.icps_inhist[ICMP_ROUTERADVERT]++);
         icmp_print (1, _LANG(icmp_type_str[type]), ip->source);
         return;

    case ICMP_ROUTERSOLICIT: /* todo !! */
         STAT (icmpstats.icps_inhist[ICMP_ROUTERSOLICIT]++);
         icmp_print (1, _LANG(icmp_type_str[type]), ip->source);
         return;

    case ICMP_TSTAMP:
         STAT (icmpstats.icps_inhist[ICMP_TSTAMP]++);
         icmp_print (1, _LANG(icmp_type_str[type]), ip->source);
         /* todo!!, send reply? */
         return;

    case ICMP_TSTAMPREPLY:
         STAT (icmpstats.icps_inhist[ICMP_TSTAMPREPLY]++);
         icmp_print (1, _LANG(icmp_type_str[type]), ip->source);
         /* todo!!, should store */
         return;

    case ICMP_IREQ:
         STAT (icmpstats.icps_inhist[ICMP_IREQ]++);
         icmp_print (1, _LANG(icmp_type_str[type]), ip->source);
         /* todo!!, send reply */
         return;

    case ICMP_IREQREPLY:
         STAT (icmpstats.icps_inhist[ICMP_IREQREPLY]++);
         icmp_print (1, _LANG(icmp_type_str[type]), ip->source);
         /* todo!!, send reply upwards */
         return;

    case ICMP_MASKREQ:
         STAT (icmpstats.icps_inhist[ICMP_MASKREQ]++);
         break;

    case ICMP_MASKREPLY:
         STAT (icmpstats.icps_inhist[ICMP_MASKREPLY]++);
         icmp_print (0, _LANG(icmp_type_str[type]), ip->source);
         if ((icmp->mask.identifier == addr_mask_id)    &&
             (icmp->mask.sequence   == addr_mask_seq-1) &&
             sin_mask != intel(icmp->mask.mask))
            outsnl ("Conflicting net-mask from \"ICMP Addr Mask Reply\"\7");
         addr_mask_id = 0;
         return;
  }
}

/*
 *  Determine which protocols we shall act upon when
 *  ICMP redirect is received
 */
void icmp_redirect (const char *value)
{
  char *val = strdup (value);

  if (val)
  {
    strupr (val);
    do_redirect.icmp = (strstr(val,"ICMP") != NULL);
    do_redirect.igmp = (strstr(val,"IGMP") != NULL);
    do_redirect.udp  = (strstr(val,"UDP")  != NULL);
    do_redirect.tcp  = (strstr(val,"TCP")  != NULL);
    free (val);
  }
}