src/ipfp/udp_fp.c

   1 #include "../common.h"
   2 #include "../prads.h"
   3 #include "ipfp.h"
   4
   5 void fp_udp4(packetinfo *pi, ip4_header * ip4, udp_header * udph, const uint8_t * end_ptr)
   6 {
   7
   8     uint8_t *opt_ptr;
   9     int32_t ilen, olen;
  10     uint32_t quirks = 0;
  11     uint8_t *payload = 0;
  12
  13     /*
  14      * Decode variable length header options and remaining data in field
  15      */
  16     olen = IP_HL(ip4) - 5;
  17     if (olen < 0) {             // Check for bad hlen
  18         olen = 0;
  19     } else {
  20         /*
  21          * Option length is number of 32 bit words
  22          */
  23         olen = olen * 4;
  24         quirks |= QUIRK_IPOPT;
  25     }
  26     /*
  27      * If the declared length is shorter than the snapshot (etherleak
  28      * or such), truncate the package.
  29      */
  30     opt_ptr = (uint8_t *) ip4 + ntohs(ip4->ip_len);
  31     if (end_ptr > opt_ptr)
  32         end_ptr = opt_ptr;
  33
  34     ilen = ip4->ip_vhl & 15;
  35     /*
  36      * B0rked packet
  37      */
  38     if (ilen < 5)
  39         return;
  40
  41     if (ilen > 5) {
  42         quirks |= QUIRK_IPOPT;
  43     }
  44     /*
  45      * If IP header ends past end_ptr
  46      */
  47     if ((uint8_t *) (ip4 + 1) > end_ptr)
  48         return;
  49
  50     if ((uint8_t *) opt_ptr + ilen < end_ptr) {
  51         quirks |= QUIRK_DATA;
  52         payload = opt_ptr + ilen;
  53     }
  54     uint8_t udata = (uint8_t *) end_ptr - payload;
  55
  56     if (!ip4->ip_id)
  57         quirks |= QUIRK_ZEROID;
  58
  59     // Fingerprint format: $fplen,$ttl,$df,$io,$if,$fo
  60     gen_fp_udp(ntohs(ip4->ip_len) - ntohs(udph->len), udata, ip4->ip_ttl,
  61                (ntohs(ip4->ip_off) & IP_DF) != 0, olen, ntohs(ip4->ip_len),
  62                ip4->ip_off, ip4->ip_tos, quirks,
  63                //ip_src, udph->src_port,AF_INET);
  64                pi);
  65
  66 //icmp_os_find_match($type,$code,$gttl,$df,$ipopts,$len,$ipflags,$foffset,$tos);
  67
  68 }