From adf170c23d179dcec29c86c22151ed19684f6209 Mon Sep 17 00:00:00 2001 From: Pascal Quantin Date: Tue, 12 Sep 2017 14:48:43 +0200 Subject: [PATCH] WebSocket: add permessage-deflate extension support Bug: 14054 Change-Id: Ib6fbb58cab4d9eb140c0911391a9c330a036cfd1 Reviewed-on: https://code.wireshark.org/review/23515 Reviewed-by: Peter Wu Petri-Dish: Peter Wu Tested-by: Petri Dish Buildbot Reviewed-by: Pascal Quantin Petri-Dish: Pascal Quantin Reviewed-by: Anders Broman --- epan/dissectors/packet-http.c | 30 +-- epan/dissectors/packet-http.h | 1 + epan/dissectors/packet-websocket.c | 292 +++++++++++++++++++++++++++-- 3 files changed, 292 insertions(+), 31 deletions(-) diff --git a/epan/dissectors/packet-http.c b/epan/dissectors/packet-http.c index cc1778a43e..0ff1979019 100644 --- a/epan/dissectors/packet-http.c +++ b/epan/dissectors/packet-http.c @@ -2444,17 +2444,18 @@ typedef struct { int special; } header_info; -#define HDR_NO_SPECIAL 0 -#define HDR_AUTHORIZATION 1 -#define HDR_AUTHENTICATE 2 -#define HDR_CONTENT_TYPE 3 -#define HDR_CONTENT_LENGTH 4 -#define HDR_CONTENT_ENCODING 5 -#define HDR_TRANSFER_ENCODING 6 -#define HDR_HOST 7 -#define HDR_UPGRADE 8 -#define HDR_COOKIE 9 -#define HDR_WEBSOCKET_PROTOCOL 10 +#define HDR_NO_SPECIAL 0 +#define HDR_AUTHORIZATION 1 +#define HDR_AUTHENTICATE 2 +#define HDR_CONTENT_TYPE 3 +#define HDR_CONTENT_LENGTH 4 +#define HDR_CONTENT_ENCODING 5 +#define HDR_TRANSFER_ENCODING 6 +#define HDR_HOST 7 +#define HDR_UPGRADE 8 +#define HDR_COOKIE 9 +#define HDR_WEBSOCKET_PROTOCOL 10 +#define HDR_WEBSOCKET_EXTENSIONS 11 static const header_info headers[] = { { "Authorization", &hf_http_authorization, HDR_AUTHORIZATION }, @@ -2479,7 +2480,7 @@ static const header_info headers[] = { { "Server", &hf_http_server, HDR_NO_SPECIAL }, { "Location", &hf_http_location, HDR_NO_SPECIAL }, { "Sec-WebSocket-Accept", &hf_http_sec_websocket_accept, HDR_NO_SPECIAL }, - { "Sec-WebSocket-Extensions", &hf_http_sec_websocket_extensions, HDR_NO_SPECIAL }, + { "Sec-WebSocket-Extensions", &hf_http_sec_websocket_extensions, HDR_WEBSOCKET_EXTENSIONS }, { "Sec-WebSocket-Key", &hf_http_sec_websocket_key, HDR_NO_SPECIAL }, { "Sec-WebSocket-Protocol", &hf_http_sec_websocket_protocol, HDR_WEBSOCKET_PROTOCOL }, { "Sec-WebSocket-Version", &hf_http_sec_websocket_version, HDR_NO_SPECIAL }, @@ -2932,6 +2933,11 @@ process_header(tvbuff_t *tvb, int offset, int next_offset, } break; + case HDR_WEBSOCKET_EXTENSIONS: + if (http_type == HTTP_RESPONSE) { + conv_data->websocket_extensions = wmem_strndup(wmem_file_scope(), value, value_len); + } + break; } } } diff --git a/epan/dissectors/packet-http.h b/epan/dissectors/packet-http.h index a4aac74217..6e5e5efce9 100644 --- a/epan/dissectors/packet-http.h +++ b/epan/dissectors/packet-http.h @@ -70,6 +70,7 @@ typedef struct _http_conv_t { guint32 req_res_num; guint8 upgrade; gchar *websocket_protocol; /* Negotiated WebSocket protocol */ + gchar *websocket_extensions; /* Negotiated WebSocket extensions */ /* Server address and port, known after first server response */ guint16 server_port; address server_addr; diff --git a/epan/dissectors/packet-websocket.c b/epan/dissectors/packet-websocket.c index 9ba8bb595c..c1e41e8605 100644 --- a/epan/dissectors/packet-websocket.c +++ b/epan/dissectors/packet-websocket.c @@ -25,13 +25,19 @@ #include "config.h" #include +#include #include #include #include +#include #include "packet-http.h" #include "packet-tcp.h" +#ifdef HAVE_ZLIB +#define ZLIB_CONST +#include +#endif /* * The information used comes from: @@ -52,6 +58,27 @@ static dissector_handle_t sip_handle; #define WEBSOCKET_SIP 3 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 +} websocket_conv_t; + +#ifdef HAVE_ZLIB +typedef struct { + guint8 *decompr_payload; + guint decompr_len; +} websocket_packet_t; +#endif /* Initialize the protocol and registered fields */ static int proto_websocket = -1; @@ -59,6 +86,7 @@ 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; @@ -81,6 +109,7 @@ static gint ett_ws_mask = -1; static gint ett_ws_control_close = -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 @@ -101,6 +130,7 @@ static const value_string ws_opcode_vals[] = { #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 @@ -146,6 +176,119 @@ tvb_unmasked(tvbuff_t *tvb, packet_info *pinfo, const guint offset, guint payloa 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) +{ + /* + * 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(wmem_packet_scope(), 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(wmem_packet_scope(), 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, 0, 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) { @@ -183,28 +326,67 @@ dissect_websocket_control_frame(tvbuff_t *tvb, packet_info *pinfo, proto_tree *t } static void -dissect_websocket_data_frame(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, proto_tree *pl_tree, guint8 opcode) +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_) { proto_item *ti; - const guint offset = 0, length = tvb_reported_length(tvb); dissector_handle_t handle = NULL; heur_dtbl_entry_t *hdtbl_entry; - conversation_t *conv; - http_conv_t *http_conv = NULL; /* try to find a dissector which accepts the data. */ - conv = find_conversation(pinfo->num, &pinfo->src, &pinfo->dst, pinfo->ptype, pinfo->srcport, pinfo->destport, 0); - if (conv) { - http_conv = (http_conv_t *)conversation_get_proto_data(conv, proto_http); + 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); + } - if (http_conv) { - if (http_conv->websocket_protocol) { - handle = dissector_get_string_handle(protocol_subdissector_table, http_conv->websocket_protocol); - } else if (!handle) { - handle = dissector_get_uint_handle(port_subdissector_table, http_conv->server_port); +#ifdef HAVE_ZLIB + if (websocket_conv && 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); + } else { + /* no context take over, initialize a new context */ + z_strm = wmem_new0(wmem_packet_scope(), z_stream); + if (inflateInit2(z_strm, wbits) == Z_OK) { + uncompress_ok = websocket_uncompress(tvb, pinfo, z_strm, &uncompressed); + } + inflateEnd(z_strm); + } + } else { + websocket_packet_t *pkt_info = + (websocket_packet_t *)p_get_proto_data(wmem_file_scope(), pinfo, proto_websocket, 0); + 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); @@ -243,7 +425,7 @@ dissect_websocket_data_frame(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree break; default: /* Unknown */ - ti = proto_tree_add_item(pl_tree, hf_ws_payload_unknown, tvb, offset, length, ENC_NA); + 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); @@ -252,7 +434,46 @@ dissect_websocket_data_frame(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree } static void -dissect_websocket_payload(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, proto_tree *ws_tree, guint8 opcode) +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. + */ + + websocket_conv->permessage_deflate = !!strstr(str, "permessage-deflate"); +#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 opcode, websocket_conv_t *websocket_conv, gboolean pmc) { const guint offset = 0, length = tvb_reported_length(tvb); proto_item *ti; @@ -282,7 +503,7 @@ dissect_websocket_payload(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, p if (opcode & 8) { /* Control frames have MSB set. */ dissect_websocket_control_frame(tvb_appdata, pinfo, pl_tree, opcode); } else { - dissect_websocket_data_frame(tvb_appdata, pinfo, tree, pl_tree, opcode); + dissect_websocket_data_frame(tvb_appdata, pinfo, tree, pl_tree, opcode, websocket_conv, pmc); } } @@ -298,6 +519,28 @@ dissect_websocket_frame(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, voi 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); + + 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; + 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; @@ -326,6 +569,11 @@ dissect_websocket_frame(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, voi 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 && 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); @@ -364,7 +612,7 @@ dissect_websocket_frame(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, voi } else { tvb_payload = tvb_new_subset_length_caplen(tvb, payload_offset, payload_length, payload_length); } - dissect_websocket_payload(tvb_payload, pinfo, tree, ws_tree, opcode); + dissect_websocket_payload(tvb_payload, pinfo, tree, ws_tree, opcode, websocket_conv, pmc); } return tvb_captured_length(tvb); @@ -428,6 +676,11 @@ proto_register_websocket(void) 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, @@ -514,7 +767,8 @@ proto_register_websocket(void) }; static ei_register_info ei[] = { - { &ei_ws_payload_unknown, { "websocket.payload.unknown.expert", PI_UNDECODED, PI_NOTE, "Dissector for Websocket Opcode", EXPFILL }}, + { &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[] = { @@ -557,8 +811,8 @@ proto_register_websocket(void) "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