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 "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         size_t i, hdr_len;
  30         struct auth_hdr *auth_ops;
  31
  32         auth_ops = (struct auth_hdr *) pkt_pull(pkt, sizeof(*auth_ops));
  33         if (auth_ops == NULL)
  34                 return;
  35
  36         hdr_len = (auth_ops->h_payload_len * 4) + 8;
  37
  38         tprintf(" [ Authentication Header ");
  39         tprintf("NextHdr (%u), ", auth_ops->h_next_header);
  40         if (hdr_len > pkt_len(pkt)) {
  41                 tprintf("HdrLen (%u, %zd Bytes %s), ",
  42                       auth_ops->h_payload_len, hdr_len,
  43                       colorize_start_full(black, red)
  44                       "invalid" colorize_end());
  45                       return;
  46         }
  47         tprintf("HdrLen (%u, %zd Bytes), ",auth_ops->h_payload_len, hdr_len);
  48         tprintf("Reserved (0x%x), ", ntohs(auth_ops->h_reserved));
  49         /* TODO
  50          * Upgrade for Extended (64-bit) Sequence Number
  51          * http://tools.ietf.org/html/rfc4302#section-2.5.1
  52          */
  53         tprintf("SPI (0x%x), ", ntohl(auth_ops->h_spi));
  54         tprintf("SNF (0x%x), ", ntohl(auth_ops->h_snf));
  55         tprintf("ICV 0x");
  56         for (i = sizeof(struct auth_hdr); i < hdr_len; i++) {
  57                 uint8_t *data = pkt_pull(pkt, 1);
  58
  59                 if (data == NULL) {
  60                         tprintf("%sinvalid%s", colorize_start_full(black, red),
  61                                 colorize_end());
  62                         break;
  63                 }
  64
  65                 tprintf("%02x", *data);
  66         }
  67         tprintf(" ]\n");
  68
  69         pkt_set_proto(pkt, &eth_lay3, auth_ops->h_next_header);
  70 }
  71
  72 static void auth_hdr_less(struct pkt_buff *pkt)
  73 {
  74         ssize_t hdr_len;
  75         struct auth_hdr *auth_ops;
  76
  77         auth_ops = (struct auth_hdr *) pkt_pull(pkt, sizeof(*auth_ops));
  78         if (auth_ops == NULL)
  79                 return;
  80
  81         hdr_len = (auth_ops->h_payload_len * 4) + 8;
  82         if (hdr_len > pkt_len(pkt) || hdr_len < 0)
  83                 return;
  84
  85         tprintf(" AH");
  86
  87         pkt_pull(pkt, hdr_len - sizeof(*auth_ops));
  88         pkt_set_proto(pkt, &eth_lay3, auth_ops->h_next_header);
  89 }
  90
  91 struct protocol ip_auth_ops = {
  92         .key = 0x33,
  93         .print_full = auth_hdr,
  94         .print_less = auth_hdr_less,
  95 };