proto_ip_authentication_hdr.c

   1 /*
   2  * netsniff-ng - the packet sniffing beast
   3  * Copyright 2012 Markus Amend <markus@netsniff-ng.org>, Deutsche Flugsicherung GmbH
   4  * Subject to the GPL, version 2.
   5  *
   6  * IP Authentication Header described in RFC4302
   7  */
   8
   9 #include <stdio.h>
  10 #include <stdint.h>
  11 #include <netinet/in.h>    /* for ntohs() */
  12
  13 #include "proto.h"
  14 #include "dissector_eth.h"
  15 #include "built_in.h"
  16 #include "pkt_buff.h"
  17
  18 struct auth_hdr {
  19         uint8_t h_next_header;
  20         uint8_t h_payload_len;
  21         uint16_t h_reserved;
  22         uint32_t h_spi;
  23         uint32_t h_snf;
  24 } __packed;
  25
  26 static void auth_hdr(struct pkt_buff *pkt)
  27 {
  28         size_t i, hdr_len;
  29         struct auth_hdr *auth_ops;
  30
  31         auth_ops = (struct auth_hdr *) pkt_pull(pkt, sizeof(*auth_ops));
  32         if (auth_ops == NULL)
  33                 return;
  34
  35         hdr_len = (auth_ops->h_payload_len * 4) + 8;
  36
  37         tprintf(" [ Authentication Header ");
  38         tprintf("NextHdr (%u), ", auth_ops->h_next_header);
  39         if (hdr_len > pkt_len(pkt)) {
  40                 tprintf("HdrLen (%u, %zd Bytes %s), ",
  41                       auth_ops->h_payload_len, hdr_len,
  42                       colorize_start_full(black, red)
  43                       "invalid" colorize_end());
  44                       return;
  45         }
  46         tprintf("HdrLen (%u, %zd Bytes), ",auth_ops->h_payload_len, hdr_len);
  47         tprintf("Reserved (0x%x), ", ntohs(auth_ops->h_reserved));
  48         /* TODO
  49          * Upgrade for Extended (64-bit) Sequence Number
  50          * http://tools.ietf.org/html/rfc4302#section-2.5.1
  51          */
  52         tprintf("SPI (0x%x), ", ntohl(auth_ops->h_spi));
  53         tprintf("SNF (0x%x), ", ntohl(auth_ops->h_snf));
  54         tprintf("ICV 0x");
  55         for (i = sizeof(struct auth_hdr); i < hdr_len; i++) {
  56                 uint8_t *data = pkt_pull(pkt, 1);
  57
  58                 if (data == NULL) {
  59                         tprintf("%sinvalid%s", colorize_start_full(black, red),
  60                                 colorize_end());
  61                         break;
  62                 }
  63
  64                 tprintf("%02x", *data);
  65         }
  66         tprintf(" ]\n");
  67
  68         pkt_set_dissector(pkt, &eth_lay3, auth_ops->h_next_header);
  69 }
  70
  71 static void auth_hdr_less(struct pkt_buff *pkt)
  72 {
  73         ssize_t hdr_len;
  74         struct auth_hdr *auth_ops;
  75
  76         auth_ops = (struct auth_hdr *) pkt_pull(pkt, sizeof(*auth_ops));
  77         if (auth_ops == NULL)
  78                 return;
  79
  80         hdr_len = (auth_ops->h_payload_len * 4) + 8;
  81         if (hdr_len > pkt_len(pkt) || hdr_len < 0)
  82                 return;
  83
  84         tprintf(" AH");
  85
  86         pkt_pull(pkt, hdr_len - sizeof(*auth_ops));
  87         pkt_set_dissector(pkt, &eth_lay3, auth_ops->h_next_header);
  88 }
  89
  90 struct protocol ip_auth_ops = {
  91         .key = 0x33,
  92         .print_full = auth_hdr,
  93         .print_less = auth_hdr_less,
  94 };