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wireshark/epan/dissectors/packet-websocket.c

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/* packet-websocket.c
* Routines for WebSocket dissection
* Copyright 2012, Alexis La Goutte <alexis.lagoutte@gmail.com>
* 2015, Peter Wu <peter@lekensteyn.nl>
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "config.h"
#include <wsutil/wslog.h>
#include <epan/addr_resolv.h>
#include <epan/conversation.h>
#include <epan/follow.h>
#include <epan/proto_data.h>
#include <epan/packet.h>
#include <epan/expert.h>
#include <epan/prefs.h>
#include <epan/reassemble.h>
#include <wsutil/strtoi.h>
#include "packet-http.h"
#include "packet-tcp.h"
#ifdef HAVE_ZLIB
#define ZLIB_CONST
#include <zlib.h>
#endif
/*
* The information used comes from:
* RFC6455: The WebSocket Protocol
* http://www.iana.org/assignments/websocket (last updated 2012-04-12)
*/
void proto_register_websocket(void);
void proto_reg_handoff_websocket(void);
static dissector_handle_t websocket_handle;
static dissector_handle_t text_lines_handle;
static dissector_handle_t json_handle;
static dissector_handle_t sip_handle;
#define WEBSOCKET_NONE 0
#define WEBSOCKET_TEXT 1
#define WEBSOCKET_JSON 2
#define WEBSOCKET_SIP 3
#define OPCODE_KEY 0
static gint pref_text_type = WEBSOCKET_NONE;
static gboolean pref_decompress = TRUE;
typedef struct {
const char *subprotocol;
guint16 server_port;
gboolean permessage_deflate;
#ifdef HAVE_ZLIB
gboolean permessage_deflate_ok;
gint8 server_wbits;
gint8 client_wbits;
z_streamp server_take_over_context;
z_streamp client_take_over_context;
#endif
guint32 frag_id;
guint8 first_frag_opcode;
} websocket_conv_t;
#ifdef HAVE_ZLIB
typedef struct {
guint8 *decompr_payload;
guint decompr_len;
} websocket_packet_t;
#endif
static int websocket_follow_tap = -1;
/* Initialize the protocol and registered fields */
static int proto_websocket = -1;
static int proto_http = -1;
static int hf_ws_fin = -1;
static int hf_ws_reserved = -1;
static int hf_ws_pmc = -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_masked_payload = -1;
static int hf_ws_payload_continue = -1;
static int hf_ws_payload_close = -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_pong = -1;
static int hf_ws_payload_unknown = -1;
static int hf_ws_fragments = -1;
static int hf_ws_fragment = -1;
static int hf_ws_fragment_overlap = -1;
static int hf_ws_fragment_overlap_conflict = -1;
static int hf_ws_fragment_multiple_tails = -1;
static int hf_ws_fragment_too_long_fragment = -1;
static int hf_ws_fragment_error = -1;
static int hf_ws_fragment_count = -1;
static int hf_ws_reassembled_length = -1;
static gint ett_ws = -1;
static gint ett_ws_pl = -1;
static gint ett_ws_mask = -1;
static gint ett_ws_control_close = -1;
static gint ett_ws_fragments = -1;
static gint ett_ws_fragment = -1;
static expert_field ei_ws_payload_unknown = EI_INIT;
static expert_field ei_ws_decompression_failed = EI_INIT;
#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_RSV1 0x40
#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}
};
static const fragment_items ws_frag_items = {
&ett_ws_fragments,
&ett_ws_fragment,
&hf_ws_fragments,
&hf_ws_fragment,
&hf_ws_fragment_overlap,
&hf_ws_fragment_overlap_conflict,
&hf_ws_fragment_multiple_tails,
&hf_ws_fragment_too_long_fragment,
&hf_ws_fragment_error,
&hf_ws_fragment_count,
NULL,
&hf_ws_reassembled_length,
/* Reassembled data field */
NULL,
"websocket fragments"
};
static dissector_table_t port_subdissector_table;
static dissector_table_t protocol_subdissector_table;
static heur_dissector_list_t heur_subdissector_list;
static reassembly_table ws_reassembly_table;
#define MAX_UNMASKED_LEN (1024 * 256)
static tvbuff_t *
tvb_unmasked(tvbuff_t *tvb, packet_info *pinfo, const guint offset, guint payload_length, const guint8 *masking_key)
{
gchar *data_unmask;
guint i;
const guint8 *data_mask;
guint unmasked_length = payload_length > MAX_UNMASKED_LEN ? MAX_UNMASKED_LEN : payload_length;
data_unmask = (gchar *)wmem_alloc(pinfo->pool, 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];
}
return tvb_new_real_data(data_unmask, unmasked_length, payload_length);
}
#ifdef HAVE_ZLIB
static gint8
websocket_extract_wbits(const gchar *str)
{
guint8 wbits;
const gchar *end;
if (str && ws_strtou8(str, &end, &wbits) &&
(*end == '\0' || strchr(";\t ", *end))) {
if (wbits < 8) {
wbits = 8;
} else if (wbits > 15) {
wbits = 15;
}
} else {
wbits = 15;
}
return -wbits;
}
static void *
websocket_zalloc(void *opaque _U_, unsigned int items, unsigned int size)
{
return wmem_alloc(wmem_file_scope(), items*size);
}
static void
websocket_zfree(void *opaque _U_, void *addr)
{
wmem_free(wmem_file_scope(), addr);
}
static z_streamp
websocket_init_z_stream_context(gint8 wbits)
{
z_streamp z_strm = wmem_new0(wmem_file_scope(), z_stream);
z_strm->zalloc = websocket_zalloc;
z_strm->zfree = websocket_zfree;
if (inflateInit2(z_strm, wbits) != Z_OK) {
inflateEnd(z_strm);
wmem_free(wmem_file_scope(), z_strm);
return NULL;
}
return z_strm;
}
/*
* Decompress the given buffer using the given zlib context. On success, the
* (possibly empty) buffer is stored as "proto data" and TRUE is returned.
* Otherwise FALSE is returned.
*/
static gboolean
websocket_uncompress(tvbuff_t *tvb, packet_info *pinfo, z_streamp z_strm, tvbuff_t **uncompressed_tvb, guint32 key)
{
/*
* Decompression a message: append "0x00 0x00 0xff 0xff" to the end of
* message, then apply DEFLATE to the result.
* https://tools.ietf.org/html/rfc7692#section-7.2.2
*/
guint8 *decompr_payload = NULL;
guint decompr_len = 0;
guint compr_len, decompr_buf_len;
guint8 *compr_payload, *decompr_buf;
gint err;
compr_len = tvb_captured_length(tvb) + 4;
compr_payload = (guint8 *)wmem_alloc(pinfo->pool, compr_len);
tvb_memcpy(tvb, compr_payload, 0, compr_len-4);
compr_payload[compr_len-4] = compr_payload[compr_len-3] = 0x00;
compr_payload[compr_len-2] = compr_payload[compr_len-1] = 0xff;
decompr_buf_len = 2*compr_len;
decompr_buf = (guint8 *)wmem_alloc(pinfo->pool, decompr_buf_len);
z_strm->next_in = compr_payload;
z_strm->avail_in = compr_len;
/* Decompress all available data. */
do {
z_strm->next_out = decompr_buf;
z_strm->avail_out = decompr_buf_len;
err = inflate(z_strm, Z_SYNC_FLUSH);
if (err == Z_OK || err == Z_STREAM_END || err == Z_BUF_ERROR) {
guint avail_bytes = decompr_buf_len - z_strm->avail_out;
if (avail_bytes) {
decompr_payload = (guint8 *)wmem_realloc(wmem_file_scope(), decompr_payload,
decompr_len + avail_bytes);
memcpy(&decompr_payload[decompr_len], decompr_buf, avail_bytes);
decompr_len += avail_bytes;
}
}
} while (err == Z_OK);
if (err == Z_STREAM_END || err == Z_BUF_ERROR) {
/* Data was (partially) uncompressed. */
websocket_packet_t *pkt_info = wmem_new0(wmem_file_scope(), websocket_packet_t);
if (decompr_len > 0) {
pkt_info->decompr_payload = decompr_payload;
pkt_info->decompr_len = decompr_len;
*uncompressed_tvb = tvb_new_real_data(decompr_payload, decompr_len, decompr_len);
}
p_add_proto_data(wmem_file_scope(), pinfo, proto_websocket, key, pkt_info);
return TRUE;
} else {
/* decompression failed */
wmem_free(wmem_file_scope(), decompr_payload);
return FALSE;
}
}
#endif
static void
dissect_websocket_control_frame(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, guint8 opcode)
{
proto_item *ti;
proto_tree *subtree;
const guint offset = 0, length = tvb_reported_length(tvb);
switch (opcode) {
case WS_CLOSE: /* Close */
ti = proto_tree_add_item(tree, hf_ws_payload_close, tvb, offset, length, ENC_NA);
subtree = proto_item_add_subtree(ti, ett_ws_control_close);
/* Close frame MAY contain a body. */
if (length >= 2) {
proto_tree_add_item(subtree, hf_ws_payload_close_status_code, tvb, offset, 2, ENC_BIG_ENDIAN);
if (length > 2)
proto_tree_add_item(subtree, hf_ws_payload_close_reason, tvb, offset+2, length-2, ENC_UTF_8);
}
break;
case WS_PING: /* Ping */
proto_tree_add_item(tree, hf_ws_payload_ping, tvb, offset, length, ENC_NA);
break;
case WS_PONG: /* Pong */
proto_tree_add_item(tree, hf_ws_payload_pong, tvb, offset, length, ENC_NA);
break;
default: /* Unknown */
ti = proto_tree_add_item(tree, hf_ws_payload_unknown, tvb, offset, length, ENC_NA);
expert_add_info_format(pinfo, ti, &ei_ws_payload_unknown, "Dissector for Websocket Opcode (%d)"
" code not implemented, Contact Wireshark developers"
" if you want this supported", opcode);
break;
}
}
static void
dissect_websocket_data_frame(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, proto_tree *pl_tree, guint8 opcode, websocket_conv_t *websocket_conv, gboolean pmc _U_, gint raw_offset _U_)
{
proto_item *ti;
dissector_handle_t handle = NULL;
heur_dtbl_entry_t *hdtbl_entry;
if (pinfo->fragmented) {
/* Skip dissecting fragmented payload data. */
return;
}
/* try to find a dissector which accepts the data. */
if (websocket_conv->subprotocol) {
handle = dissector_get_string_handle(protocol_subdissector_table, websocket_conv->subprotocol);
} else if (websocket_conv->server_port) {
handle = dissector_get_uint_handle(port_subdissector_table, websocket_conv->server_port);
}
#ifdef HAVE_ZLIB
if (websocket_conv->permessage_deflate_ok && pmc) {
tvbuff_t *uncompressed = NULL;
gboolean uncompress_ok = FALSE;
if (!PINFO_FD_VISITED(pinfo)) {
z_streamp z_strm;
gint8 wbits;
if (pinfo->destport == websocket_conv->server_port) {
z_strm = websocket_conv->server_take_over_context;
wbits = websocket_conv->server_wbits;
} else {
z_strm = websocket_conv->client_take_over_context;
wbits = websocket_conv->client_wbits;
}
if (z_strm) {
uncompress_ok = websocket_uncompress(tvb, pinfo, z_strm, &uncompressed, raw_offset);
} else {
/* no context take over, initialize a new context */
z_strm = wmem_new0(pinfo->pool, z_stream);
if (inflateInit2(z_strm, wbits) == Z_OK) {
uncompress_ok = websocket_uncompress(tvb, pinfo, z_strm, &uncompressed, raw_offset);
}
inflateEnd(z_strm);
}
} else {
websocket_packet_t *pkt_info =
(websocket_packet_t *)p_get_proto_data(wmem_file_scope(), pinfo, proto_websocket, raw_offset);
if (pkt_info) {
uncompress_ok = TRUE;
if (pkt_info->decompr_len > 0) {
uncompressed = tvb_new_real_data(pkt_info->decompr_payload, pkt_info->decompr_len, pkt_info->decompr_len);
}
}
}
if (!uncompress_ok) {
proto_tree_add_expert(tree, pinfo, &ei_ws_decompression_failed, tvb, 0, -1);
return;
}
if (uncompressed) {
add_new_data_source(pinfo, uncompressed, "Decompressed payload");
tvb = uncompressed;
}
}
#endif
if (handle) {
call_dissector_only(handle, tvb, pinfo, tree, NULL);
return; /* handle found, assume dissector took care of it. */
} else if (dissector_try_heuristic(heur_subdissector_list, tvb, pinfo, tree, &hdtbl_entry, NULL)) {
return; /* heuristics dissector handled it. */
}
/* no dissector wanted it, try to print something appropriate. */
switch (opcode) {
case WS_TEXT: /* Text */
{
const gchar *saved_match_string = pinfo->match_string;
pinfo->match_string = NULL;
switch (pref_text_type) {
case WEBSOCKET_TEXT:
case WEBSOCKET_NONE:
default:
/* Assume that most text protocols are line-based. */
call_dissector(text_lines_handle, tvb, pinfo, tree);
break;
case WEBSOCKET_JSON:
call_dissector(json_handle, tvb, pinfo, tree);
break;
case WEBSOCKET_SIP:
call_dissector(sip_handle, tvb, pinfo, tree);
break;
}
pinfo->match_string = saved_match_string;
}
break;
case WS_BINARY: /* Binary */
call_data_dissector(tvb, pinfo, tree);
break;
default: /* Unknown */
ti = proto_tree_add_item(pl_tree, hf_ws_payload_unknown, tvb, 0, -1, ENC_NA);
expert_add_info_format(pinfo, ti, &ei_ws_payload_unknown, "Dissector for Websocket Opcode (%d)"
" code not implemented, Contact Wireshark developers"
" if you want this supported", opcode);
break;
}
}
static void
websocket_parse_extensions(websocket_conv_t *websocket_conv, const char *str)
{
/*
* Grammar for the header:
*
* Sec-WebSocket-Extensions = extension-list
* extension-list = 1#extension
* extension = extension-token *( ";" extension-param )
* extension-token = registered-token
* registered-token = token
* extension-param = token [ "=" (token | quoted-string) ]
*/
/*
* RFC 7692 permessage-deflate parsing.
* "x-webkit-deflate-frame" is an alias used by some versions of Safari browser
*/
websocket_conv->permessage_deflate = !!strstr(str, "permessage-deflate")
|| !!strstr(str, "x-webkit-deflate-frame");
#ifdef HAVE_ZLIB
websocket_conv->permessage_deflate_ok = pref_decompress &&
websocket_conv->permessage_deflate;
if (websocket_conv->permessage_deflate_ok) {
websocket_conv->server_wbits =
websocket_extract_wbits(strstr(str, "server_max_window_bits="));
if (!strstr(str, "server_no_context_takeover")) {
websocket_conv->server_take_over_context =
websocket_init_z_stream_context(websocket_conv->server_wbits);
}
websocket_conv->client_wbits =
websocket_extract_wbits(strstr(str, "client_max_window_bits="));
if (!strstr(str, "client_no_context_takeover")) {
websocket_conv->client_take_over_context =
websocket_init_z_stream_context(websocket_conv->client_wbits);
}
}
#endif
}
static void
dissect_websocket_payload(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, proto_tree *ws_tree, guint8 fin, guint8 opcode, websocket_conv_t *websocket_conv, gboolean pmc, gint raw_offset)
{
const guint offset = 0, length = tvb_reported_length(tvb);
proto_item *ti;
proto_tree *pl_tree;
tvbuff_t *tvb_appdata;
tvbuff_t *frag_tvb = NULL;
/* Payload */
ti = proto_tree_add_item(ws_tree, hf_ws_payload, tvb, offset, length, ENC_NA);
pl_tree = proto_item_add_subtree(ti, ett_ws_pl);
/* Extension Data */
/* TODO: Add dissector of Extension (not extension available for the moment...) */
if (opcode & 8) { /* Control frames have MSB set. */
dissect_websocket_control_frame(tvb, pinfo, pl_tree, opcode);
return;
}
bool save_fragmented = pinfo->fragmented;
if (!fin || opcode == WS_CONTINUE) {
/* Fragmented data frame */
fragment_head *frag_msg;
pinfo->fragmented = TRUE;
if (!PINFO_FD_VISITED(pinfo) && opcode != WS_CONTINUE) {
/* First fragment, temporarily save opcode needed when dissecting the reassembled frame */
websocket_conv->first_frag_opcode = opcode;
}
frag_msg = fragment_add_seq_next(&ws_reassembly_table, tvb, offset,
pinfo, websocket_conv->frag_id,
NULL, tvb_captured_length_remaining(tvb, offset),
!fin);
frag_tvb = process_reassembled_data(tvb, offset, pinfo,
"Reassembled Message", frag_msg, &ws_frag_items,
NULL, tree);
}
if (!PINFO_FD_VISITED(pinfo) && frag_tvb) {
/* First time fragments fully reassembled, store opcode from first fragment */
p_add_proto_data(wmem_file_scope(), pinfo, proto_websocket, OPCODE_KEY,
GUINT_TO_POINTER(websocket_conv->first_frag_opcode));
}
if (frag_tvb) {
/* Fragments were fully reassembled. */
tvb_appdata = frag_tvb;
/* Lookup opcode from first fragment */
guint first_frag_opcode = GPOINTER_TO_UINT(
p_get_proto_data(wmem_file_scope(),pinfo, proto_websocket, OPCODE_KEY));
opcode = (guint8)first_frag_opcode;
} else {
/* Right now this is exactly the same, this may change when exts. are added.
tvb_appdata = tvb_new_subset_length_caplen(tvb, offset, length, length);
*/
tvb_appdata = tvb;
}
/* Application Data */
if (pinfo->fragmented && opcode == WS_CONTINUE) {
/* Not last fragment, dissect continue fragment as is */
proto_tree_add_item(tree, hf_ws_payload_continue, tvb_appdata, offset, length, ENC_NA);
return;
}
dissect_websocket_data_frame(tvb_appdata, pinfo, tree, pl_tree, opcode, websocket_conv, pmc, raw_offset);
pinfo->fragmented = save_fragmented;
}
static int
dissect_websocket_frame(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
{
static guint32 frag_id_counter = 0;
proto_item *ti, *ti_len;
guint8 fin, opcode;
gboolean mask;
guint short_length, payload_length;
guint payload_offset, mask_offset;
proto_tree *ws_tree;
const guint8 *masking_key = NULL;
tvbuff_t *tvb_payload;
conversation_t *conv;
websocket_conv_t *websocket_conv;
gboolean pmc = FALSE;
/*
* If this is a new Websocket session, try to parse HTTP Sec-Websocket-*
* headers once.
*/
conv = find_or_create_conversation(pinfo);
websocket_conv = (websocket_conv_t *)conversation_get_proto_data(conv, proto_websocket);
if (!websocket_conv) {
websocket_conv = wmem_new0(wmem_file_scope(), websocket_conv_t);
websocket_conv->frag_id = ++frag_id_counter;
http_conv_t *http_conv = (http_conv_t *)conversation_get_proto_data(conv, proto_http);
if (http_conv) {
websocket_conv->subprotocol = http_conv->websocket_protocol;
websocket_conv->server_port = http_conv->server_port;
if ( http_conv->websocket_extensions) {
websocket_parse_extensions(websocket_conv, http_conv->websocket_extensions);
}
}
conversation_add_proto_data(conv, proto_websocket, websocket_conv);
}
short_length = tvb_get_guint8(tvb, 1) & MASK_WS_PAYLOAD_LEN;
mask_offset = 2;
if (short_length == 126) {
payload_length = tvb_get_ntohs(tvb, 2);
mask_offset += 2;
} else if (short_length == 127) {
/* warning C4244: '=' : conversion from 'guint64' to 'guint ', possible loss of data */
payload_length = (guint)tvb_get_ntoh64(tvb, 2);
mask_offset += 8;
} else {
payload_length = short_length;
}
/* Mask */
mask = (tvb_get_guint8(tvb, 1) & MASK_WS_MASK) != 0;
payload_offset = mask_offset + (mask ? 4 : 0);
col_set_str(pinfo->cinfo, COL_PROTOCOL, "WebSocket");
col_set_str(pinfo->cinfo, COL_INFO, "WebSocket");
ti = proto_tree_add_item(tree, proto_websocket, tvb, 0, payload_offset, ENC_NA);
ws_tree = proto_item_add_subtree(ti, ett_ws);
/* Flags */
proto_tree_add_item(ws_tree, hf_ws_fin, tvb, 0, 1, ENC_NA);
fin = (tvb_get_guint8(tvb, 0) & MASK_WS_FIN) >> 4;
proto_tree_add_item(ws_tree, hf_ws_reserved, tvb, 0, 1, ENC_BIG_ENDIAN);
if (websocket_conv->permessage_deflate) {
/* RSV1 is Per-Message Compressed bit (RFC 7692). */
pmc = !!(tvb_get_guint8(tvb, 0) & MASK_WS_RSV1);
proto_tree_add_item(ws_tree, hf_ws_pmc, tvb, 0, 1, ENC_BIG_ENDIAN);
}
/* Opcode */
proto_tree_add_item(ws_tree, hf_ws_opcode, tvb, 0, 1, ENC_BIG_ENDIAN);
opcode = tvb_get_guint8(tvb, 0) & MASK_WS_OPCODE;
col_append_fstr(pinfo->cinfo, COL_INFO, " %s", val_to_str_const(opcode, ws_opcode_vals, "Unknown Opcode"));
col_append_str(pinfo->cinfo, COL_INFO, fin ? " [FIN]" : "[FRAGMENT] ");
/* Add Mask bit to the tree */
proto_tree_add_item(ws_tree, hf_ws_mask, tvb, 1, 1, ENC_NA);
col_append_str(pinfo->cinfo, COL_INFO, mask ? " [MASKED]" : " ");
/* (Extended) Payload Length */
ti_len = proto_tree_add_item(ws_tree, hf_ws_payload_length, tvb, 1, 1, ENC_BIG_ENDIAN);
if (short_length == 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, 2, 2, ENC_BIG_ENDIAN);
}
else if (short_length == 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, 2, 8, ENC_BIG_ENDIAN);
}
/* Masking-key */
if (mask) {
proto_tree_add_item(ws_tree, hf_ws_masking_key, tvb, mask_offset, 4, ENC_NA);
masking_key = tvb_get_ptr(tvb, mask_offset, 4);
}
if (payload_length > 0) {
/* Always unmask payload data before analysing it. */
if (mask) {
proto_tree_add_item(ws_tree, hf_ws_masked_payload, tvb, payload_offset, payload_length, ENC_NA);
tvb_payload = tvb_unmasked(tvb, pinfo, payload_offset, payload_length, masking_key);
tvb_set_child_real_data_tvbuff(tvb, tvb_payload);
add_new_data_source(pinfo, tvb_payload, "Unmasked data");
} else {
tvb_payload = tvb_new_subset_length_caplen(tvb, payload_offset, payload_length, payload_length);
}
dissect_websocket_payload(tvb_payload, pinfo, tree, ws_tree, fin, opcode, websocket_conv, pmc, tvb_raw_offset(tvb));
if (have_tap_listener(websocket_follow_tap)) {
tap_queue_packet(websocket_follow_tap, pinfo, tvb_payload);
}
}
return tvb_captured_length(tvb);
}
static guint
get_websocket_frame_length(packet_info *pinfo _U_, tvbuff_t *tvb, int offset, void *data _U_)
{
guint frame_length, payload_length;
gboolean mask;
frame_length = 2; /* flags, opcode and Payload length */
mask = tvb_get_guint8(tvb, offset + 1) & MASK_WS_MASK;
payload_length = tvb_get_guint8(tvb, offset + 1) & MASK_WS_PAYLOAD_LEN;
offset += 2; /* Skip flags, opcode and Payload length */
/* Check for Extended Payload Length. */
if (payload_length == 126) {
if (tvb_reported_length_remaining(tvb, offset) < 2)
return 0; /* Need more data. */
payload_length = tvb_get_ntohs(tvb, offset);
frame_length += 2; /* Extended payload length */
} else if (payload_length == 127) {
if (tvb_reported_length_remaining(tvb, offset) < 8)
return 0; /* Need more data. */
payload_length = (guint)tvb_get_ntoh64(tvb, offset);
frame_length += 8; /* Extended payload length */
}
if (mask)
frame_length += 4; /* Masking-key */
frame_length += payload_length; /* Payload data */
return frame_length;
}
static int
dissect_websocket(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
{
/* Need at least two bytes for flags, opcode and Payload length. */
tcp_dissect_pdus(tvb, pinfo, tree, TRUE, 2,
get_websocket_frame_length, dissect_websocket_frame, data);
return tvb_captured_length(tvb);
}
static gboolean
test_websocket(packet_info* pinfo _U_, tvbuff_t* tvb, int offset _U_, void* data _U_)
{
guint buffer_length = tvb_captured_length(tvb);
// At least 2 bytes are required for a websocket header
if (buffer_length < 2)
{
return FALSE;
}
guint8 first_byte = tvb_get_guint8(tvb, 0);
guint8 second_byte = tvb_get_guint8(tvb, 1);
// Reserved bits RSV1, RSV2 and RSV3 need to be 0
if ((first_byte & 0x70) > 0)
{
return FALSE;
}
guint8 op_code = first_byte & 0x0F;
// op_code must be one of WS_CONTINUE, WS_TEXT, WS_BINARY, WS_CLOSE, WS_PING or WS_PONG
if (!(op_code == WS_CONTINUE || op_code == WS_TEXT || op_code == WS_BINARY || op_code == WS_CLOSE || op_code == WS_PING || op_code == WS_PONG))
{
return FALSE;
}
// It is necessary to prevent that HTTP connection setups are treated as websocket.
// If HTTP catches and it upgrades to websocket then HTTP takes care that websocket dissector gets called for this stream.
// If first two byte start with printable characters from the alphabet it's likely that it is part of a HTTP connection setup.
if (((first_byte >= 'a' && first_byte <= 'z') || (first_byte >= 'A' && first_byte <= 'Z')) &&
((second_byte >= 'a' && second_byte <= 'z') || (second_byte >= 'A' && second_byte <= 'Z')))
{
return FALSE;
}
return TRUE;
}
static gboolean
dissect_websocket_heur_tcp(tvbuff_t* tvb, packet_info* pinfo, proto_tree* tree, void* data)
{
if (!test_websocket(pinfo, tvb, 0, data))
{
return FALSE;
}
conversation_t* conversation = find_or_create_conversation(pinfo);
conversation_set_dissector(conversation, websocket_handle);
tcp_dissect_pdus(tvb, pinfo, tree, TRUE, 2, get_websocket_frame_length, dissect_websocket_frame, data);
return TRUE;
}
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_pmc,
{ "Per-Message Compressed", "websocket.pmc",
FT_BOOLEAN, 8, NULL, MASK_WS_RSV1,
"Whether a message is compressed or not", 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 (64 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,
"Payload (after unmasking)", HFILL }
},
{ &hf_ws_masked_payload,
{ "Masked payload", "websocket.masked_payload",
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_close,
{ "Close", "websocket.payload.close",
FT_NONE, BASE_NONE, NULL, 0x0,
NULL, HFILL }
},
{ &hf_ws_payload_close_status_code,
{ "Status code", "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_pong,
{ "Pong", "websocket.payload.pong",
FT_BYTES, BASE_NONE, NULL, 0x0,
NULL, HFILL }
},
{ &hf_ws_payload_unknown,
{ "Unknown", "websocket.payload.unknown",
FT_BYTES, BASE_NONE, NULL, 0x0,
NULL, HFILL }
},
/* Reassembly */
{ &hf_ws_fragments,
{ "Reassembled websocket Fragments", "websocket.fragments",
FT_NONE, BASE_NONE, NULL, 0x0,
"Fragments", HFILL }
},
{ &hf_ws_fragment,
{ "Websocket Fragment", "websocket.fragment",
FT_FRAMENUM, BASE_NONE, NULL, 0x0,
NULL, HFILL }
},
{ &hf_ws_fragment_overlap,
{ "Fragment overlap", "websocket.fragment.overlap",
FT_BOOLEAN, BASE_NONE, NULL, 0x0,
"Fragment overlaps with other fragments", HFILL }
},
{ &hf_ws_fragment_overlap_conflict,
{ "Conflicting data in fragment overlap", "websocket.fragment.overlap.conflict",
FT_BOOLEAN, BASE_NONE, NULL, 0x0,
"Overlapping fragments contained conflicting data", HFILL }
},
{ &hf_ws_fragment_multiple_tails,
{ "Multiple tail fragments found", "websocket.fragment.multipletails",
FT_BOOLEAN, BASE_NONE, NULL, 0x0,
"Several tails were found when defragmenting the packet", HFILL }
},
{ &hf_ws_fragment_too_long_fragment,
{ "Fragment too long", "websocket.fragment.toolongfragment",
FT_BOOLEAN, BASE_NONE, NULL, 0x0,
"Fragment contained data past end of packet", HFILL }
},
{ &hf_ws_fragment_error,
{ "Defragmentation error", "websocket.fragment.error",
FT_FRAMENUM, BASE_NONE, NULL, 0x0,
"Defragmentation error due to illegal fragments", HFILL }
},
{ &hf_ws_fragment_count,
{ "Fragment count", "websocket.fragment.count",
FT_UINT32, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_ws_reassembled_length,
{ "Reassembled websocket Payload length", "websocket.reassembled.length",
FT_UINT32, BASE_DEC, NULL, 0x0,
"The total length of the reassembled payload", HFILL }
},
};
static gint *ett[] = {
&ett_ws,
&ett_ws_pl,
&ett_ws_mask,
&ett_ws_control_close,
&ett_ws_fragment,
&ett_ws_fragments,
};
static ei_register_info ei[] = {
{ &ei_ws_payload_unknown, { "websocket.payload.unknown.expert", PI_UNDECODED, PI_NOTE, "Dissector for Websocket Opcode", EXPFILL }},
{ &ei_ws_decompression_failed, { "websocket.decompression.failed.expert", PI_PROTOCOL, PI_WARN, "Decompression failed", EXPFILL }},
};
static const enum_val_t text_types[] = {
{"None", "No subdissection", WEBSOCKET_NONE},
{"Line based text", "Line based text", WEBSOCKET_TEXT},
{"As JSON", "As json", WEBSOCKET_JSON},
{"As SIP", "As SIP", WEBSOCKET_SIP},
{NULL, NULL, -1}
};
module_t *websocket_module;
expert_module_t* expert_websocket;
proto_websocket = proto_register_protocol("WebSocket",
"WebSocket", "websocket");
/*
* Heuristic dissectors SHOULD register themselves in
* this table using the standard heur_dissector_add()
* function.
*/
heur_subdissector_list = register_heur_dissector_list("ws", proto_websocket);
port_subdissector_table = register_dissector_table("ws.port",
"TCP port for protocols using WebSocket", proto_websocket, FT_UINT16, BASE_DEC);
protocol_subdissector_table = register_dissector_table("ws.protocol",
"Negotiated WebSocket protocol", proto_websocket, FT_STRING, BASE_NONE);
reassembly_table_register(&ws_reassembly_table, &addresses_reassembly_table_functions);
websocket_follow_tap = register_tap("websocket_follow"); /* websocket follow tap */
register_follow_stream(proto_websocket, "websocket_follow", tcp_follow_conv_filter, tcp_follow_index_filter,
tcp_follow_address_filter, tcp_port_to_display, follow_tvb_tap_listener,
get_tcp_stream_count, NULL);
proto_register_field_array(proto_websocket, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
expert_websocket = expert_register_protocol(proto_websocket);
expert_register_field_array(expert_websocket, ei, array_length(ei));
websocket_handle = register_dissector("websocket", dissect_websocket, proto_websocket);
websocket_module = prefs_register_protocol(proto_websocket, NULL);
prefs_register_enum_preference(websocket_module, "text_type",
"Dissect websocket text as",
"Select dissector for websocket text",
&pref_text_type, text_types, WEBSOCKET_NONE);
prefs_register_bool_preference(websocket_module, "decompress",
"Try to decompress permessage-deflate payload", NULL, &pref_decompress);
}
void
proto_reg_handoff_websocket(void)
{
dissector_add_string("http.upgrade", "websocket", websocket_handle);
dissector_add_for_decode_as("tcp.port", websocket_handle);
heur_dissector_add("tcp", dissect_websocket_heur_tcp, "WebSocket Heuristic", "websocket_tcp", proto_websocket, HEURISTIC_DISABLE);
text_lines_handle = find_dissector_add_dependency("data-text-lines", proto_websocket);
json_handle = find_dissector_add_dependency("json", proto_websocket);
sip_handle = find_dissector_add_dependency("sip", proto_websocket);
proto_http = proto_get_id_by_filter_name("http");
}
/*
* Editor modelines - https://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:
*/
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