src/proto_ip_authentication_hdr.c

   1 /*
   2  * netsniff-ng - the packet sniffing beast
   3  * Copyright 2012 Markus Amend <markus@netsniff-ng.org>
   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 "protos.h"
  15 #include "dissector_eth.h"
  16 #include "built_in.h"
  17 #include "pkt_buff.h"
  18
  19 struct auth_hdr {
  20         uint8_t h_next_header;
  21         uint8_t h_payload_len;
  22         uint16_t h_reserved;
  23         uint32_t h_spi;
  24         uint32_t h_snf;
  25 } __packed;
  26
  27 static void auth_hdr(struct pkt_buff *pkt)
  28 {
  29         uint16_t hdr_len;
  30         struct auth_hdr *auth_ops;
  31
  32         auth_ops = (struct auth_hdr *) pkt_pull(pkt, sizeof(*auth_ops));
  33         hdr_len = (auth_ops->h_payload_len * 4) + 8;
  34         if (auth_ops == NULL)
  35                 return;
  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, %s), ", hdr_len,
  41                         colorize_start_full(black, red),
  42                         "invalid" colorize_end());
  43                 return;
  44         }
  45         tprintf("HdrLen (%u), ", hdr_len);
  46         tprintf("Reserved (0x%x), ", ntohs(auth_ops->h_reserved));
  47         /* TODO
  48          * Upgrade for Extended (64-bit) Sequence Number
  49          * http://tools.ietf.org/html/rfc4302#section-2.5.1
  50          */
  51         tprintf("SPI (0x%x), ", ntohl(auth_ops->h_spi));
  52         tprintf("SNF (0x%x), ", ntohl(auth_ops->h_snf));
  53         tprintf("ICV 0x");
  54         for (size_t i = sizeof(struct auth_hdr); i < hdr_len; i++)
  55                 tprintf("%02x", *pkt_pull(pkt, 1));
  56         tprintf(" ]\n");
  57
  58         pkt_set_proto(pkt, &eth_lay3, auth_ops->h_next_header);
  59 }
  60
  61 static void auth_hdr_less(struct pkt_buff *pkt)
  62 {
  63         uint16_t hdr_len;
  64         struct auth_hdr *auth_ops;
  65
  66         auth_ops = (struct auth_hdr *) pkt_pull(pkt, sizeof(*auth_ops));
  67         hdr_len = (auth_ops->h_payload_len * 4) + 8;
  68         if (auth_ops == NULL || hdr_len > pkt_len(pkt))
  69                 return;
  70
  71         tprintf(" AH");
  72
  73         pkt_pull(pkt, hdr_len - sizeof(*auth_ops));
  74         pkt_set_proto(pkt, &eth_lay3, auth_ops->h_next_header);
  75 }
  76
  77 struct protocol ip_auth_ops = {
  78         .key = 0x33,
  79         .print_full = auth_hdr,
  80         .print_less = auth_hdr_less,
  81 };
  82
  83 EXPORT_SYMBOL(ip_auth_hdr_ops);