path: root/epan/dissectors/packet-websocket.c

/* packet-websocket.c
 * Routines for WebSocket dissection
 * Copyright 2012, Alexis La Goutte <alexis.lagoutte@gmail.com>
 *
 * $Id$
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#include <glib.h>

#include <epan/packet.h>
#include <epan/expert.h>

/*
 * The information used comes from:
 * RFC6455: The WebSocket Protocol
 * http://www.iana.org/assignments/websocket (last updated 2012-04-12)
 */

/* Initialize the protocol and registered fields */
static int proto_websocket = -1;
static int hf_ws_fin = -1;
static int hf_ws_reserved = -1;
static int hf_ws_opcode = -1;
static int hf_ws_mask = -1;
static int hf_ws_payload_length = -1;
static int hf_ws_payload_length_ext_16 = -1;
static int hf_ws_payload_length_ext_64 = -1;
static int hf_ws_masking_key = -1;
static int hf_ws_payload = -1;
static int hf_ws_payload_unmask = -1;
static int hf_ws_payload_continue = -1;
static int hf_ws_payload_text = -1;
static int hf_ws_payload_text_mask = -1;
static int hf_ws_payload_text_unmask = -1;
static int hf_ws_payload_binary = -1;
static int hf_ws_payload_binary_mask = -1;
static int hf_ws_payload_binary_unmask = -1;
static int hf_ws_payload_close = -1;
static int hf_ws_payload_close_mask = -1;
static int hf_ws_payload_close_unmask = -1;
static int hf_ws_payload_close_status_code = -1;
static int hf_ws_payload_close_reason = -1;
static int hf_ws_payload_ping = -1;
static int hf_ws_payload_ping_mask = -1;
static int hf_ws_payload_ping_unmask = -1;
static int hf_ws_payload_pong = -1;
static int hf_ws_payload_pong_mask = -1;
static int hf_ws_payload_pong_unmask = -1;
static int hf_ws_payload_unknown = -1;

static gint ett_ws = -1;
static gint ett_ws_pl = -1;
static gint ett_ws_mask = -1;

#define WS_CONTINUE 0x0
#define WS_TEXT     0x1
#define WS_BINARY   0x2
#define WS_CLOSE    0x8
#define WS_PING     0x9
#define WS_PONG     0xA

static const value_string ws_opcode_vals[] = {
  { WS_CONTINUE, "Continuation" },
  { WS_TEXT, "Text" },
  { WS_BINARY, "Binary" },
  { WS_CLOSE, "Connection Close" },
  { WS_PING, "Ping" },
  { WS_PONG, "Pong" },
  { 0, 	NULL}
};

#define MASK_WS_FIN 0x80
#define MASK_WS_RSV 0x70
#define MASK_WS_OPCODE  0x0F
#define MASK_WS_MASK  0x80
#define MASK_WS_PAYLOAD_LEN 0x7F

static const value_string ws_close_status_code_vals[] = {
  { 1000, "Normal Closure" },
  { 1001, "Going Away" },
  { 1002, "Protocol error" },
  { 1003, "Unsupported Data" },
  { 1004, "---Reserved----" },
  { 1005, "No Status Rcvd" },
  { 1006, "Abnormal Closure" },
  { 1007, "Invalid frame payload data" },
  { 1008, "Policy Violation" },
  { 1009, "Message Too Big" },
  { 1010, "Mandatory Ext." },
  { 1011, "Internal Server" },
  { 1015, "TLS handshake" },
  { 0, 	NULL}
};

#define MAX_UNMASKED_LEN (1024 * 64)
tvbuff_t *
tvb_unmasked(tvbuff_t *tvb, const int offset, int payload_length, const guint8 *masking_key)
{

  gchar *data_unmask;
  tvbuff_t  *tvb_unmask    = NULL;
  int i;
  const guint8 *data_mask;
  int unmasked_length = payload_length > MAX_UNMASKED_LEN ? MAX_UNMASKED_LEN : payload_length;

  data_unmask = g_malloc(unmasked_length);
  data_mask = tvb_get_ptr(tvb, offset, unmasked_length);
  /* Unmasked(XOR) Data... */
  for(i=0; i < unmasked_length; i++){
    data_unmask[i] = data_mask[i] ^ masking_key[i%4];
  }

  tvb_unmask = tvb_new_real_data(data_unmask, unmasked_length, unmasked_length);
  tvb_set_free_cb(tvb_unmask, g_free);
  return tvb_unmask;
}

static int
dissect_websocket_payload(tvbuff_t *tvb, packet_info *pinfo, proto_tree *ws_tree, guint8 opcode, guint64 payload_length, guint8 mask, const guint8* masking_key)
{
  int offset = 0;
  int payload_length_32bit;
  proto_item *ti_unmask, *ti;
  proto_tree *pl_tree, *mask_tree = NULL;
  tvbuff_t  *unmask_tvb    = NULL;

  /* Wireshark does not handle packets larger than 2^31-1 bytes. */
  payload_length_32bit = (int)payload_length;
  if (payload_length != (guint64)payload_length_32bit) {
    proto_tree_add_text(ws_tree, tvb, offset, -1, "Payload length %" G_GINT64_MODIFIER "u is too large to dissect",
                        payload_length);
    return tvb_length(tvb);
  }

  /* Payload */
  ti = proto_tree_add_item(ws_tree, hf_ws_payload, tvb, offset, payload_length_32bit, ENC_NA);
  pl_tree = proto_item_add_subtree(ti, ett_ws_pl);
  if(mask){
    unmask_tvb = tvb_unmasked(tvb, offset, payload_length_32bit, masking_key);
    tvb_set_child_real_data_tvbuff(tvb, unmask_tvb);
    add_new_data_source(pinfo, unmask_tvb, payload_length_32bit > (int) tvb_length(unmask_tvb) ? "Unmasked Data (truncated)" : "Unmasked Data");
    ti = proto_tree_add_item(ws_tree, hf_ws_payload_unmask, unmask_tvb, offset, payload_length_32bit, ENC_NA);
    mask_tree = proto_item_add_subtree(ti, ett_ws_mask);
  }

  /* Extension Data */
  /* TODO: Add dissector of Extension (not extension available for the moment...) */

  /* Application Data */
  switch(opcode){

    case WS_CONTINUE: /* Continue */
      proto_tree_add_item(pl_tree, hf_ws_payload_continue, tvb, offset, payload_length_32bit, ENC_NA);
      /* TODO: Add Fragmentation support... */
    break;

    case WS_TEXT: /* Text */
    if(mask){

      proto_tree_add_item(pl_tree, hf_ws_payload_text_mask, tvb, offset, payload_length_32bit, ENC_NA);
      ti_unmask = proto_tree_add_item(mask_tree, hf_ws_payload_text_unmask, unmask_tvb, offset, payload_length_32bit,  ENC_UTF_8|ENC_NA);
      PROTO_ITEM_SET_GENERATED(ti_unmask);
      ti_unmask = proto_tree_add_item(mask_tree, hf_ws_payload_text, unmask_tvb, offset, payload_length_32bit,  ENC_UTF_8|ENC_NA);
      PROTO_ITEM_SET_HIDDEN(ti_unmask);
    }else{
      proto_tree_add_item(pl_tree, hf_ws_payload_text, tvb, offset, payload_length_32bit, ENC_UTF_8|ENC_NA);

    }
    offset += payload_length_32bit;
    break;

    case WS_BINARY: /* Binary */
    if(mask){
      proto_tree_add_item(pl_tree, hf_ws_payload_binary_mask, tvb, offset, payload_length_32bit, ENC_NA);
      ti_unmask = proto_tree_add_item(mask_tree, hf_ws_payload_binary_unmask, unmask_tvb, offset, payload_length_32bit, ENC_NA);
      PROTO_ITEM_SET_GENERATED(ti_unmask);
      ti_unmask = proto_tree_add_item(mask_tree, hf_ws_payload_binary, unmask_tvb, offset, payload_length_32bit, ENC_NA);
      PROTO_ITEM_SET_HIDDEN(ti_unmask);
    }else{
      proto_tree_add_item(pl_tree, hf_ws_payload_binary, tvb, offset, payload_length_32bit, ENC_NA);
    }
    offset += payload_length_32bit;
    break;

    case WS_CLOSE: /* Close */
    if(mask){
      proto_tree_add_item(pl_tree, hf_ws_payload_close_mask, tvb, offset, payload_length_32bit, ENC_NA);
      ti_unmask = proto_tree_add_item(mask_tree, hf_ws_payload_close_unmask, unmask_tvb, offset, payload_length_32bit, ENC_NA);
      PROTO_ITEM_SET_GENERATED(ti_unmask);
      ti_unmask = proto_tree_add_item(mask_tree, hf_ws_payload_close, unmask_tvb, offset, payload_length_32bit, ENC_NA);
      PROTO_ITEM_SET_HIDDEN(ti_unmask);
      ti_unmask = proto_tree_add_item(mask_tree, hf_ws_payload_close_status_code, unmask_tvb, offset, 2, ENC_BIG_ENDIAN);
      PROTO_ITEM_SET_GENERATED(ti_unmask);

      if(payload_length_32bit > 2){
        ti_unmask = proto_tree_add_item(mask_tree, hf_ws_payload_close_reason, unmask_tvb, offset+2, payload_length_32bit-2, ENC_ASCII|ENC_NA);
        PROTO_ITEM_SET_GENERATED(ti_unmask);
      }
    }else{
      proto_tree_add_item(pl_tree, hf_ws_payload_close, tvb, offset, payload_length_32bit, ENC_NA);
      proto_tree_add_item(pl_tree, hf_ws_payload_close_status_code, tvb, offset, 2, ENC_BIG_ENDIAN);
      if(payload_length_32bit > 2){
        proto_tree_add_item(pl_tree, hf_ws_payload_close_reason, tvb, offset+2, payload_length_32bit-2, ENC_ASCII|ENC_NA);
      }
    }
    offset += payload_length_32bit;
    break;

    case WS_PING: /* Ping */
    if(mask){
      proto_tree_add_item(pl_tree, hf_ws_payload_ping_mask, tvb, offset, payload_length_32bit, ENC_NA);
      ti_unmask = proto_tree_add_item(mask_tree, hf_ws_payload_ping_unmask, unmask_tvb, offset, payload_length_32bit, ENC_NA);
      PROTO_ITEM_SET_GENERATED(ti_unmask);
      ti_unmask = proto_tree_add_item(mask_tree, hf_ws_payload_ping, unmask_tvb, offset, payload_length_32bit, ENC_NA);
      PROTO_ITEM_SET_HIDDEN(ti_unmask);
    }else{
      proto_tree_add_item(pl_tree, hf_ws_payload_ping, tvb, offset, payload_length_32bit, ENC_NA);
    }
    offset += payload_length_32bit;
    break;

    case WS_PONG: /* Pong */
    if(mask){
      proto_tree_add_item(pl_tree, hf_ws_payload_pong_mask, tvb, offset, payload_length_32bit, ENC_NA);
      ti_unmask = proto_tree_add_item(mask_tree, hf_ws_payload_pong_unmask, unmask_tvb, offset, payload_length_32bit, ENC_NA);
      PROTO_ITEM_SET_GENERATED(ti_unmask);
      ti_unmask = proto_tree_add_item(mask_tree, hf_ws_payload_pong, unmask_tvb, offset, payload_length_32bit, ENC_NA);
      PROTO_ITEM_SET_HIDDEN(ti_unmask);
    }else{
      proto_tree_add_item(pl_tree, hf_ws_payload_pong, tvb, offset, payload_length_32bit, ENC_NA);
    }
    offset += payload_length_32bit;
    break;

    default: /* Unknown */
      ti = proto_tree_add_item(pl_tree, hf_ws_payload_unknown, tvb, offset, payload_length_32bit, ENC_NA);
      expert_add_info_format(pinfo, ti, PI_UNDECODED, PI_NOTE, "Dissector for Websocket Opcode (%d)"
                                       " code not implemented, Contact Wireshark developers"
                                       " if you want this supported", opcode);
    break;
  }
  return offset;
}
static int
dissect_websocket(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
{

  proto_item *ti, *ti_len;
  proto_tree *ws_tree = NULL;
  int offset = 0;
  guint8 fin, opcode, mask;
  const guint8 *masking_key = NULL;
  guint64 payload_length;
  tvbuff_t  *tvb_payload    = NULL;
  col_set_str(pinfo->cinfo, COL_PROTOCOL, "WebSocket");
  col_set_str(pinfo->cinfo, COL_INFO, "WebSocket");
  if (tree) {

    ti = proto_tree_add_item(tree, proto_websocket, tvb, 0, -1, ENC_NA);
    ws_tree = proto_item_add_subtree(ti, ett_ws);

  }
  /* Flags */
  proto_tree_add_item(ws_tree, hf_ws_fin, tvb, offset, 1, ENC_NA);
  fin = (tvb_get_guint8(tvb, offset) & MASK_WS_FIN) >> 4;
  proto_tree_add_item(ws_tree, hf_ws_reserved, tvb, offset, 1, ENC_NA);

  /* Opcode */
  proto_tree_add_item(ws_tree, hf_ws_opcode, tvb, offset, 1, ENC_NA);
  opcode = tvb_get_guint8(tvb, offset) & MASK_WS_OPCODE;
  col_append_fstr(pinfo->cinfo, COL_INFO, " %s", val_to_str_const(opcode, ws_opcode_vals, "Unknown Opcode"));
  col_append_fstr(pinfo->cinfo, COL_INFO, " %s", fin ? "[FIN]" : "");
  offset +=1;

  /* Mask */
  proto_tree_add_item(ws_tree, hf_ws_mask, tvb, offset, 1, ENC_NA);
  mask = (tvb_get_guint8(tvb, offset) & MASK_WS_MASK) >> 4;
  col_append_fstr(pinfo->cinfo, COL_INFO, " %s", mask ? "[MASKED]" : "");

  /* (Extended) Payload Length */
  ti_len = proto_tree_add_item(ws_tree, hf_ws_payload_length, tvb, offset, 1, ENC_NA);
  payload_length = (guint64)tvb_get_guint8(tvb, offset) & MASK_WS_PAYLOAD_LEN;
  offset +=1;
  switch(payload_length){
    case 126:
      proto_item_append_text(ti_len, " Extended Payload Length (16 bits)");
      proto_tree_add_item(ws_tree, hf_ws_payload_length_ext_16, tvb, offset, 2, ENC_BIG_ENDIAN);
      payload_length = (guint64)tvb_get_ntohs(tvb, offset);
      offset += 2;
    break;
    case 127:
      proto_item_append_text(ti_len, " Extended Payload Length (64 bits)");
      proto_tree_add_item(ws_tree, hf_ws_payload_length_ext_64, tvb, offset, 8, ENC_BIG_ENDIAN);
      payload_length = tvb_get_ntoh64(tvb, offset);
      offset += 8;
    break;
    default:
    break;
  }

  /* Masking-key */
  if(mask){
    proto_tree_add_item(ws_tree, hf_ws_masking_key, tvb, offset, 4, ENC_NA);
    masking_key = tvb_get_ptr(tvb, offset, 4);
    offset += 4;
  }

  tvb_payload = tvb_new_subset_remaining(tvb, offset);
  offset += dissect_websocket_payload(tvb_payload, pinfo, ws_tree, opcode, payload_length, mask, masking_key);

  return offset;
}


void
proto_register_websocket(void)
{

  static hf_register_info hf[] = {
    { &hf_ws_fin,
      { "Fin", "websocket.fin",
      FT_BOOLEAN, 8, NULL, MASK_WS_FIN,
      "Indicates that this is the final fragment in a message", HFILL }
    },
    { &hf_ws_reserved,
      { "Reserved", "websocket.rsv",
      FT_UINT8, BASE_HEX, NULL, MASK_WS_RSV,
      "Must be zero", HFILL }
    },
    { &hf_ws_opcode,
      { "Opcode", "websocket.opcode",
      FT_UINT8, BASE_DEC, VALS(ws_opcode_vals), MASK_WS_OPCODE,
      "Defines the interpretation of the Payload data", HFILL }
    },
    { &hf_ws_mask,
      { "Mask", "websocket.mask",
      FT_BOOLEAN, 8, NULL, MASK_WS_MASK,
      "Defines whether the Payload data is masked", HFILL }
    },
    { &hf_ws_payload_length,
      { "Payload length", "websocket.payload_length",
      FT_UINT8, BASE_DEC, NULL, MASK_WS_PAYLOAD_LEN,
      "The length of the Payload data", HFILL }
    },
    { &hf_ws_payload_length_ext_16,
      { "Extended Payload length (16 bits)", "websocket.payload_length_ext_16",
      FT_UINT16, BASE_DEC, NULL, 0x0,
      "The length (16 bits) of the Payload data", HFILL }
    },
    { &hf_ws_payload_length_ext_64,
      { "Extended Payload length (16 bits)", "websocket.payload_length_ext_64",
      FT_UINT64, BASE_DEC, NULL, 0x0,
      "The length (64 bits) of the Payload data", HFILL }
    },
    { &hf_ws_masking_key,
      { "Masking-Key", "websocket.masking_key",
      FT_BYTES, BASE_NONE, NULL, 0x0,
      "All frames sent from the client to the server are masked by a 32-bit value that is contained within the frame", HFILL }
    },
    { &hf_ws_payload,
      { "Payload", "websocket.payload",
      FT_NONE, BASE_NONE, NULL, 0x0,
      NULL, HFILL }
    },
    { &hf_ws_payload_unmask,
      { "Unmask Payload", "websocket.payload.unmask",
      FT_NONE, BASE_NONE, NULL, 0x0,
      NULL, HFILL }
    },
    { &hf_ws_payload_continue,
      { "Continue", "websocket.payload.continue",
      FT_BYTES, BASE_NONE, NULL, 0x0,
      NULL, HFILL }
    },
    { &hf_ws_payload_text,
      { "Text", "websocket.payload.text",
      FT_STRING, BASE_NONE, NULL, 0x0,
      NULL, HFILL }
    },
    { &hf_ws_payload_text_mask,
      { "Text", "websocket.payload.text_mask",
      FT_BYTES, BASE_NONE, NULL, 0x0,
      NULL, HFILL }
    },
    { &hf_ws_payload_text_unmask,
      { "Text unmask", "websocket.payload.text_unmask",
      FT_STRING, BASE_NONE, NULL, 0x0,
      NULL, HFILL }
    },
    { &hf_ws_payload_binary,
      { "Binary", "websocket.payload.binary",
      FT_BYTES, BASE_NONE, NULL, 0x0,
      NULL, HFILL }
    },
    { &hf_ws_payload_binary_mask,
      { "Binary", "websocket.payload.binary_mask",
      FT_BYTES, BASE_NONE, NULL, 0x0,
      NULL, HFILL }
    },
    { &hf_ws_payload_binary_unmask,
      { "Binary", "websocket.payload.binary_unmask",
      FT_BYTES, BASE_NONE, NULL, 0x0,
      NULL, HFILL }
    },
    { &hf_ws_payload_close,
      { "Close", "websocket.payload.close",
      FT_BYTES, BASE_NONE, NULL, 0x0,
      NULL, HFILL }
    },
    { &hf_ws_payload_close_mask,
      { "Close", "websocket.payload.close_mask",
      FT_BYTES, BASE_NONE, NULL, 0x0,
      NULL, HFILL }
    },
    { &hf_ws_payload_close_unmask,
      { "Unmask Close", "websocket.payload.close_unmask",
      FT_BYTES, BASE_NONE, NULL, 0x0,
      NULL, HFILL }
    },
    { &hf_ws_payload_close_status_code,
      { "Close", "websocket.payload.close.status_code",
      FT_UINT16, BASE_DEC, VALS(ws_close_status_code_vals), 0x0,
      NULL, HFILL }
    },
    { &hf_ws_payload_close_reason,
      { "Reason", "websocket.payload.close.reason",
      FT_STRING, BASE_NONE, NULL, 0x0,
      NULL, HFILL }
    },
    { &hf_ws_payload_ping,
      { "Ping", "websocket.payload.ping",
      FT_BYTES, BASE_NONE, NULL, 0x0,
      NULL, HFILL }
    },
    { &hf_ws_payload_ping_mask,
      { "Ping", "websocket.payload.ping_mask",
      FT_BYTES, BASE_NONE, NULL, 0x0,
      NULL, HFILL }
    },
    { &hf_ws_payload_ping_unmask,
      { "Ping", "websocket.payload.ping_unmask",
      FT_BYTES, BASE_NONE, NULL, 0x0,
      NULL, HFILL }
    },
    { &hf_ws_payload_pong,
      { "Pong", "websocket.payload.pong",
      FT_BYTES, BASE_NONE, NULL, 0x0,
      NULL, HFILL }
    },
    { &hf_ws_payload_pong_mask,
      { "Pong", "websocket.payload.pong_mask",
      FT_BYTES, BASE_NONE, NULL, 0x0,
      NULL, HFILL }
    },
    { &hf_ws_payload_pong_unmask,
      { "Pong", "websocket.payload.pong_unmask",
      FT_BYTES, BASE_NONE, NULL, 0x0,
      NULL, HFILL }
    },
    { &hf_ws_payload_unknown,
      { "Unknown", "websocket.payload.unknown",
      FT_BYTES, BASE_NONE, NULL, 0x0,
      NULL, HFILL }
    },
  };


  static gint *ett[] = {
    &ett_ws,
    &ett_ws_pl,
    &ett_ws_mask
  };

  proto_websocket = proto_register_protocol("WebSocket",
      "WebSocket", "websocket");

  proto_register_field_array(proto_websocket, hf, array_length(hf));
  proto_register_subtree_array(ett, array_length(ett));

  new_register_dissector("websocket", dissect_websocket, proto_websocket);
}


/*
 * Editor modelines  -  http://www.wireshark.org/tools/modelines.html
 *
 * Local variables:
 * c-basic-offset: 2
 * tab-width: 8
 * indent-tabs-mode: nil
 * End:
 *
 * vi: set shiftwidth=2 tabstop=8 expandtab:
 * :indentSize=2:tabSize=8:noTabs=true:
 */