epan/dissectors/packet-peap.c

   1 /* packet-peap.c
   2  * Routines for PEAP (Protected Extensible Authentication Protocol)
   3  * draft-kamath-pppext-peapv0
   4  *
   5  * Wireshark - Network traffic analyzer
   6  * By Gerald Combs <gerald@wireshark.org>
   7  * Copyright 1998 Gerald Combs
   8  *
   9  * SPDX-License-Identifier: GPL-2.0-or-later
  10  */
  11
  12 #include "config.h"
  13
  14 #include <stdio.h>
  15
  16 #include <epan/packet.h>
  17 #include <epan/eap.h>
  18 #include <epan/expert.h>
  19 #include <wsutil/pint.h>
  20 #include <epan/proto_data.h>
  21
  22 void proto_register_peap(void);
  23 void proto_reg_handoff_peap(void);
  24
  25 static int proto_peap;
  26 static int proto_eap;
  27
  28 static dissector_handle_t peap_handle;
  29 static dissector_handle_t eap_handle;
  30
  31 /*
  32   From draft-kamath-pppext-peapv0, sec 1.1
  33
  34     0                   1                   2                   3
  35     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
  36    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  37    |     Code      |   Identifier  |            Length             | <-- NOT sent
  38    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  39    |     Type      |   Value...
  40    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  41
  42    This matches the format of an EAP header but...
  43     * 'Code', 'Identifier' and 'Length' are NOT sent over the wire
  44     * 'Code' and 'Identifier' are extracted from the *outer* EAP header
  45     * 'Length' is derived from the PEAP packet (ie. TLS data frame)
  46     * ...when 'Type' is 33, the full EAP header is sent
  47 */
  48
  49 #define EAP_TLS_FLAGS_OFFSET   5
  50 #define EAP_TLS_FLAGS_VERSION  0x07 /* mask */
  51
  52 static int
  53 dissect_peap(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
  54 {
  55   int version;
  56   int len;
  57   int offset = 0;
  58   tvbuff_t *eap_tvb, *eap_len_tvb, *next_tvb;
  59   unsigned char *eap_len_buf;
  60   uint32_t tls_group = pinfo->curr_proto_layer_num << 16;
  61
  62   col_set_str(pinfo->cinfo, COL_PROTOCOL, "PEAP");
  63   col_clear(pinfo->cinfo, COL_INFO);
  64
  65   len = tvb_reported_length(tvb);
  66
  67   eap_tvb = (tvbuff_t *)p_get_proto_data(pinfo->pool, pinfo, proto_eap, PROTO_DATA_EAP_TVB | tls_group);
  68   version = tvb_get_uint8(eap_tvb, EAP_TLS_FLAGS_OFFSET) & EAP_TLS_FLAGS_VERSION;
  69   if (version > 0) {    /* FIXME support v1 and v2 */
  70     goto ret;
  71   }
  72
  73   if (!(   len >= 5
  74         && tvb_get_bits(tvb, offset, 16, ENC_BIG_ENDIAN) == tvb_get_bits(eap_tvb, 0, 16, ENC_BIG_ENDIAN)
  75         && tvb_get_uint16(tvb, offset + 2, ENC_BIG_ENDIAN) <= tvb_get_uint16(eap_tvb, 2, ENC_BIG_ENDIAN)
  76         && (
  77                 (tvb_get_uint8(eap_tvb, 0) == EAP_REQUEST && tvb_get_uint8(tvb, offset + 4) == EAP_TYPE_ID)
  78              || tvb_get_uint8(tvb, offset + 4) == EAP_TYPE_MSAUTH_TLV
  79            ))) {
  80     eap_len_buf = (unsigned char *)wmem_alloc(pinfo->pool, 2);
  81     eap_len_tvb = tvb_new_child_real_data(tvb, eap_len_buf, 2, 2);
  82     phton16(eap_len_buf, 4 + len);
  83
  84     next_tvb = tvb_new_composite();
  85     tvb_composite_append(next_tvb, tvb_new_subset_length(eap_tvb, 0, 2));
  86     tvb_composite_append(next_tvb, eap_len_tvb);
  87     tvb_composite_append(next_tvb, tvb_new_subset_length(tvb, offset, 4 + len));
  88     tvb_composite_finalize(next_tvb);
  89
  90     add_new_data_source(pinfo, next_tvb, "Pseudo EAP");
  91   } else {
  92     next_tvb = tvb;
  93   }
  94
  95   call_dissector(eap_handle, next_tvb, pinfo, tree);
  96
  97 ret:
  98   return len;
  99 }
 100
 101 void
 102 proto_register_peap(void)
 103 {
 104   proto_peap = proto_register_protocol("Protected Extensible Authentication Protocol",
 105                                        "PEAP", "peap");
 106   peap_handle = register_dissector("peap", dissect_peap, proto_peap);
 107 }
 108
 109 void
 110 proto_reg_handoff_peap(void)
 111 {
 112   proto_eap = proto_get_id_by_filter_name("eap");
 113   eap_handle = find_dissector_add_dependency("eap", proto_peap);
 114 }
 115 /*
 116  * Editor modelines
 117  *
 118  * Local Variables:
 119  * c-basic-offset: 2
 120  * tab-width: 8
 121  * indent-tabs-mode: nil
 122  * End:
 123  *
 124  * ex: set shiftwidth=2 tabstop=8 expandtab:
 125  * :indentSize=2:tabSize=8:noTabs=true:
 126  */