Added support for the Couchbase BLIP protocol

Documentation for the protocol is available at https://github.com/couchbaselabs/BLIP-Cpp/blob/master/docs/BLIP%20Protocol.md

Bug: 15212
Change-Id: I2fe947c3af10c53d68c740241466e2de6c4be551
Reviewed-on: https://code.wireshark.org/review/30229
Petri-Dish: Michael Mann <mmann78@netscape.net>
Tested-by: Petri Dish Buildbot
Reviewed-by: Michael Mann <mmann78@netscape.net>

2 files changed, 539 insertions, 0 deletions

diff --git a/epan/dissectors/CMakeLists.txt b/epan/dissectors/CMakeLists.txt
index a011fff31b..b6d06c1852 100644
--- a/epan/dissectors/CMakeLists.txt
+++ b/epan/dissectors/CMakeLists.txt
@@ -710,6 +710,7 @@ set(DISSECTOR_SRC
 	${CMAKE_CURRENT_SOURCE_DIR}/packet-bitcoin.c
 	${CMAKE_CURRENT_SOURCE_DIR}/packet-bittorrent.c
 	${CMAKE_CURRENT_SOURCE_DIR}/packet-bjnp.c
+	${CMAKE_CURRENT_SOURCE_DIR}/packet-blip.c
 	${CMAKE_CURRENT_SOURCE_DIR}/packet-bluecom.c
 	${CMAKE_CURRENT_SOURCE_DIR}/packet-bluetooth.c
 	${CMAKE_CURRENT_SOURCE_DIR}/packet-bmc.c
diff --git a/epan/dissectors/packet-blip.c b/epan/dissectors/packet-blip.c
new file mode 100644
index 0000000000..4c33c43104
--- /dev/null
+++ b/epan/dissectors/packet-blip.c
@@ -0,0 +1,538 @@
+/* packet-blip.c
+ *
+ * BLIP protocol for Couchbase Lite <-> Sync Gateway 2.0+ Replication
+ *
+ * Spec: https://github.com/couchbaselabs/BLIP-Cpp/blob/master/docs/BLIP%20Protocol.md
+ *
+ * Copyright 2018, Traun Leyden <traun@couchbase.com>
+ * Copyright 2018, Jim Borden <jim.borden@couchbase.com>
+ *
+ * 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 <epan/packet.h>
+#include <epan/tvbparse.h>
+#include <wsutil/wsjson.h>
+
+#include <wsutil/str_util.h>
+#include <wsutil/unicode-utils.h>
+#include <epan/conversation.h>
+
+#include <wiretap/wtap.h>
+#include <stdio.h>
+#include <zlib.h>
+
+#include "packet-http.h"
+
+#define BLIP_BODY_CHECKSUM_SIZE 4
+#define BLIP_INFLATE_BUFFER_SIZE 16384
+
+// blip_conversation_entry_t is metadata that the blip dissector associates w/ each wireshark conversation
+typedef struct {
+
+	// Keep track of the largest frame number seen.  This is useful for determining whether
+	// this is the first frame in a request message or not.
+
+	// key: msgtype:srcport:messagenumber -> value: frame number for the _first_ frame in this request message
+	// Example: "MSG:23243:56" -> 12
+	// which means: "the first frame for blip message number 56, originating from source port 23243, and for message type = MSG
+	//				 ... occurred in wireshark packet #12"
+	wmem_map_t *blip_requests;
+
+} blip_conversation_entry_t;
+
+
+// File level variables
+static dissector_handle_t blip_handle;
+static int proto_blip = -1;
+static int hf_blip_message_number = -1;
+static int hf_blip_frame_flags = -1;
+static int hf_blip_properties_length = -1;
+static int hf_blip_properties = -1;
+static int hf_blip_message_body = -1;
+static int hf_blip_ack_size = -1;
+static int hf_blip_checksum = -1;
+static gint ett_blip = -1;
+static wmem_map_t* decompress_streams = NULL;
+
+// Compressed = 0x08
+// Urgent	  = 0x10
+// NoReply	  = 0x20
+// MoreComing = 0x40
+// In ascending order so that a binary search will be used as per the
+// README.dissector
+static const value_string flag_combos[] = {
+	{ 0x00, "None" },
+	{ 0x08, "Compressed" },
+	{ 0x10, "Urgent" },
+	{ 0x10|0x08, "Compressed|Urgent" },
+	{ 0x20, "NoReply" },
+	{ 0x20|0x08, "Compressed|NoReply" },
+	{ 0x20|0x10, "Urgent|NoReply" },
+	{ 0x20|0x10|0x08, "Compressed|Urgent|NoReply" },
+	{ 0x40, "MoreComing" },
+	{ 0x40|0x08, "Compressed|MoreComing" },
+	{ 0x40|0x10, "Urgent|MoreComing" },
+	{ 0x40|0x10|0x08, "Compressed|Urgent|MoreComing" },
+	{ 0x40|0x20, "NoReply|MoreComing" },
+	{ 0x40|0x20|0x08, "Compressed|NoReply|MoreComing" },
+	{ 0x40|0x20|0x10, "Urgent|NoReply|MoreComing" },
+	{ 0x40|0x20|0x10|0x08, "Compressed|Urgent|NoReply|MoreComing" },
+	{ 0, NULL }
+};
+
+static value_string_ext flag_combos_ext = VALUE_STRING_EXT_INIT(flag_combos);
+
+static const val64_string msg_types[] = {
+	{ 0x00ll, "MSG" },
+	{ 0x01ll, "RPY" },
+	{ 0x02ll, "ERR" },
+	{ 0x04ll, "ACKMSG" },
+	{ 0x05ll, "ACKRPY" },
+	{ 0, NULL }
+};
+
+// MSG =	0x00
+// RPY =	0x01
+// ERR =	0x02
+// ACKMSG = 0x04
+// ACKRPY = 0x05
+static const gchar*
+get_message_type(guint64 value_frame_flags)
+{
+	// Mask out the least significant bits: 0000 0111
+	guint64 type_mask_val = (0x07ll & value_frame_flags);
+	return val64_to_str_const(type_mask_val, msg_types, "???");
+}
+
+static gboolean
+is_ack_message(guint64 value_frame_flags) {
+	// Note, even though this is a 64-bit int, only the least significant byte has meaningful		 information,
+	// since frame flags all fit into one byte at the time this code was written.
+
+	// Mask out the least significant bits: 0000 0111
+	guint64 type_mask_val = (0x07ll & value_frame_flags);
+
+	// ACKMSG
+	if (type_mask_val == 0x04ll) {
+		return TRUE;
+	}
+
+	// ACKRPY
+	if (type_mask_val == 0x05ll) {
+		return TRUE;
+	}
+
+	return FALSE;
+}
+
+static gboolean
+is_compressed(guint64 value_frame_flags)
+{
+	// Note, even though this is a 64-bit int, only the least significant byte has meaningful information,
+	// since frame flags all fit into one byte at the time this code was written.
+
+	if ((0x08ll & value_frame_flags) == 0x08ll) {
+		return TRUE;
+	}
+
+	return FALSE;
+
+}
+
+static gchar*
+message_hash_key_convo(packet_info *pinfo,
+				  guint64 value_frame_flags,
+				  guint64 value_message_num)
+{
+	// Derive the hash key to use
+	// msgtype:srcport:destport:messagenum
+
+	const gchar *msg_type = get_message_type(value_frame_flags);
+	gchar *hash_key = wmem_strdup_printf(wmem_packet_scope(), "%s:%u:%u:%lu",
+			msg_type, pinfo->srcport, pinfo->destport, value_message_num);
+
+	return hash_key;
+}
+
+// Finds out whether this is the first blip frame in the blip message (which can consist of a series of frames).
+// If it is, updates the conversation_entry_ptr->blip_requests hash to record the pinfo->num (wireshark packet number)
+static gboolean
+is_first_frame_in_msg(blip_conversation_entry_t *conversation_entry_ptr, packet_info *pinfo,
+					  guint64 value_frame_flags, guint64 value_message_num) {
+
+	gboolean first_frame_in_msg = TRUE;
+
+	// Temporary pool for the lookup hash_key.	Will get duplicated on the file_scope() pool if needed to be
+	// stored in the hashtable.
+	gchar *hash_key = message_hash_key_convo(pinfo, value_frame_flags, value_message_num);
+	guint* first_frame_number_for_msg = (guint*)wmem_map_lookup(conversation_entry_ptr->blip_requests, (void *) hash_key);
+
+	if (first_frame_number_for_msg != NULL) {
+		if (GPOINTER_TO_UINT(first_frame_number_for_msg) != pinfo->num) {
+			first_frame_in_msg = FALSE;
+		}
+	} else {
+		// If storing the key in the hashmap, re-allocate it with the file_scope() allocator
+		gchar *hash_key_copy = wmem_strdup(wmem_file_scope(), hash_key);
+
+		wmem_map_insert(conversation_entry_ptr->blip_requests, (void *) hash_key_copy, GUINT_TO_POINTER(pinfo->num));
+	}
+
+	return first_frame_in_msg;
+}
+
+static int
+handle_ack_message(tvbuff_t *tvb, _U_ packet_info *pinfo, _U_ proto_tree *blip_tree, _U_ gint offset, _U_ guint64 value_frame_flags)
+{
+	// This gets the number of ack bytes received  as a var int in order to find out how much to bump
+	// the offset for the next proto_tree item
+	guint64 value_ack_size;
+	guint varint_ack_size_length = tvb_get_varint(
+			tvb,
+			offset,
+			FT_VARINT_MAX_LEN,
+			&value_ack_size,
+			ENC_VARINT_PROTOBUF);
+
+	proto_tree_add_item(blip_tree, hf_blip_ack_size, tvb, offset, varint_ack_size_length, ENC_VARINT_PROTOBUF);
+
+	offset += varint_ack_size_length;
+
+	return tvb_captured_length(tvb);
+}
+
+static gchar*
+message_hash_key_decompress(packet_info *pinfo)
+{
+	// Derive the hash key to use
+	// srcport:destport
+
+	gchar *hash_key = wmem_strdup_printf(wmem_packet_scope(), "%u:%u", pinfo->srcport, pinfo->destport);
+
+	return hash_key;
+}
+
+static z_stream* get_decompress_stream(packet_info* pinfo)
+{
+	if(!decompress_streams) {
+		decompress_streams = wmem_map_new(wmem_file_scope(), g_str_hash, g_str_equal);
+	}
+
+	gchar* hash_key = message_hash_key_decompress(pinfo);
+	z_stream* decompress_stream = (z_stream*)wmem_map_lookup(decompress_streams, (void *) hash_key);
+	if(decompress_stream) {
+		return decompress_stream;
+	}
+
+	gchar *hash_key_copy = wmem_strdup(wmem_file_scope(), hash_key);
+	decompress_stream = wmem_new0(wmem_file_scope(), z_stream);
+	wmem_map_insert(decompress_streams, hash_key_copy, decompress_stream);
+	return decompress_stream;
+}
+
+static tvbuff_t*
+decompress(packet_info* pinfo, tvbuff_t* tvb, gint offset, gint length)
+{
+	z_stream* decompress_stream = get_decompress_stream(pinfo);
+	static Byte trailer[4] = { 0x00, 0x00, 0xff, 0xff };
+	if(!decompress_stream->next_out) {
+		decompress_stream->zalloc = 0;
+		decompress_stream->zfree = 0;
+		decompress_stream->opaque = 0;
+		int err = inflateInit2(decompress_stream, -MAX_WBITS);
+		if(err != Z_OK) {
+			decompress_stream->next_out = 0;
+			REPORT_DISSECTOR_BUG("Unable to create INFLATE context to decompress messages");
+			return NULL;
+		}
+	}
+
+	const guint8* buf = tvb_get_ptr(tvb, offset, length);
+	Bytef* decompress_buffer = (Bytef*)wmem_alloc(wmem_packet_scope(), BLIP_INFLATE_BUFFER_SIZE);
+	decompress_stream->next_in = (Bytef*)buf;
+	decompress_stream->avail_in = length;
+	decompress_stream->next_out = decompress_buffer;
+	decompress_stream->avail_out = BLIP_INFLATE_BUFFER_SIZE;
+	uLong start = decompress_stream->total_out;
+	int err = inflate(decompress_stream, Z_NO_FLUSH);
+	if(err < 0) {
+		return NULL;
+	}
+
+	decompress_stream->next_in = trailer;
+	decompress_stream->avail_in = 4;
+	err = inflate(decompress_stream, Z_SYNC_FLUSH);
+	if(err < 0) {
+		return NULL;
+	}
+
+	uLong bodyLength = decompress_stream->total_out - start;
+	guint8* poolBuffer = (guint8*)wmem_alloc(pinfo->pool, bodyLength);
+	memcpy(poolBuffer, decompress_buffer, bodyLength);
+	tvbuff_t* decompressedChild = tvb_new_real_data(poolBuffer, (guint)bodyLength, (gint)bodyLength);
+	add_new_data_source(pinfo, decompressedChild, "Decompressed Payload");
+	return decompressedChild;
+ }
+
+static int
+dissect_blip(tvbuff_t *tvb, _U_ packet_info *pinfo, proto_tree *tree, _U_ void *data)
+{
+
+	proto_tree *blip_tree;
+	gint		offset = 0;
+
+	/* Set the protcol column to say BLIP */
+	col_set_str(pinfo->cinfo, COL_PROTOCOL, "BLIP");
+	/* Clear out stuff in the info column */
+	col_clear(pinfo->cinfo,COL_INFO);
+
+	// ------------------------------------- Setup BLIP tree -----------------------------------------------------------
+
+
+	/* Add a subtree to dissection.  See WSDG 9.2.2. Dissecting the details of the protocol  */
+	proto_item *blip_item = proto_tree_add_item(tree, proto_blip, tvb, offset, -1, ENC_NA);
+
+	blip_tree = proto_item_add_subtree(blip_item, ett_blip);
+
+
+	// ------------------------ BLIP Frame Header: Message Number VarInt -----------------------------------------------
+
+	// This gets the message number as a var int in order to find out how much to bump
+	// the offset for the next proto_tree item
+	guint64 value_message_num;
+	guint varint_message_num_length = tvb_get_varint(
+			tvb,
+			offset,
+			FT_VARINT_MAX_LEN,
+			&value_message_num,
+			ENC_VARINT_PROTOBUF);
+
+	proto_tree_add_item(blip_tree, hf_blip_message_number, tvb, offset, varint_message_num_length, ENC_VARINT_PROTOBUF);
+
+	offset += varint_message_num_length;
+
+	// ------------------------ BLIP Frame Header: Frame Flags VarInt --------------------------------------------------
+
+	// This gets the message number as a var int in order to find out how much to bump
+	// the offset for the next proto_tree item
+	guint64 value_frame_flags;
+	guint varint_frame_flags_length = tvb_get_varint(
+			tvb,
+			offset,
+			FT_VARINT_MAX_LEN,
+			&value_frame_flags,
+			ENC_VARINT_PROTOBUF);
+
+	guint64 masked = value_frame_flags & ~0x07;
+	proto_tree_add_uint(blip_tree, hf_blip_frame_flags, tvb, offset, varint_frame_flags_length, (guint8)masked);
+
+	offset += varint_frame_flags_length;
+
+	const gchar* msg_type = get_message_type(value_frame_flags);
+	gchar* msg_num = wmem_strdup_printf(wmem_packet_scope(), "#%" G_GUINT64_FORMAT, value_message_num);
+	gchar* col_info = wmem_strconcat(wmem_packet_scope(), msg_type, msg_num, NULL);
+	col_add_str(pinfo->cinfo, COL_INFO, col_info);
+
+	// If it's an ACK message, handle that separately, since there are no properties etc.
+	if (is_ack_message(value_frame_flags) == TRUE) {
+		return handle_ack_message(tvb, pinfo, blip_tree, offset, value_frame_flags);
+	}
+
+
+	// ------------------------------------- Conversation Tracking -----------------------------------------------------
+
+	// Create a new conversation if needed and associate the blip_conversation_entry_t with it
+	// Adapted from sample code in https://raw.githubusercontent.com/wireshark/wireshark/master/doc/README.dissector
+	conversation_t *conversation;
+	conversation = find_or_create_conversation(pinfo);
+	blip_conversation_entry_t *conversation_entry_ptr = (blip_conversation_entry_t*)conversation_get_proto_data(conversation, proto_blip);
+	if (conversation_entry_ptr == NULL) {
+
+		// create a new blip_conversation_entry_t
+		conversation_entry_ptr = wmem_new(wmem_file_scope(), blip_conversation_entry_t);
+
+		// create a new hash map and save a reference in blip_conversation_entry_t
+		conversation_entry_ptr->blip_requests = wmem_map_new(wmem_file_scope(), g_str_hash, g_str_equal);
+
+	}
+
+	// Is this the first frame in a blip message with multiple frames?
+	gboolean first_frame_in_msg = is_first_frame_in_msg(
+			conversation_entry_ptr,
+			pinfo,
+			value_frame_flags,
+			value_message_num
+	);
+
+	// Update the conversation w/ the latest version of the blip_conversation_entry_t
+	conversation_add_proto_data(conversation, proto_blip, (void *)conversation_entry_ptr);
+
+	tvbuff_t* tvb_to_use = tvb;
+	gboolean compressed = is_compressed(value_frame_flags);
+	if(compressed) {
+		if(!tree) {
+			// This is just a preliminary pass, no protocol tree to fill in so
+			// don't waste time decompressing (it will probably mess things up
+			// anyway)
+			return tvb_reported_length(tvb);
+		}
+
+		tvb_to_use = decompress(pinfo, tvb, offset, tvb_reported_length_remaining(tvb, offset) - BLIP_BODY_CHECKSUM_SIZE);
+		if(!tvb_to_use) {
+			proto_tree_add_string(blip_tree, hf_blip_message_body, tvb, offset, tvb_reported_length_remaining(tvb, offset), "<Error decompressing message>");
+			return tvb_reported_length(tvb);
+		}
+
+		offset = 0;
+	}
+
+	// Is this the first frame in a message?
+	if (first_frame_in_msg == TRUE) {
+
+		// ------------------------ BLIP Frame Header: Properties Length VarInt --------------------------------------------------
+
+		// WARNING: this only works because this code assumes that ALL MESSAGES FIT INTO ONE FRAME, which is absolutely not true.
+		// In other words, as soon as there is a message that spans two frames, this code will break.
+
+		guint64 value_properties_length;
+		guint value_properties_length_varint_length = tvb_get_varint(
+				tvb_to_use,
+				offset,
+				FT_VARINT_MAX_LEN,
+				&value_properties_length,
+				ENC_VARINT_PROTOBUF);
+
+		proto_tree_add_item(blip_tree, hf_blip_properties_length, tvb_to_use, offset, value_properties_length_varint_length, ENC_VARINT_PROTOBUF);
+
+		offset += value_properties_length_varint_length;
+
+		// ------------------------ BLIP Frame: Properties --------------------------------------------------
+
+		// WARNING: this only works because this code assumes that ALL MESSAGES FIT INTO ONE FRAME, which is absolutely not true.
+		// In other words, as soon as there is a message that spans two frames, this code will break.
+
+		// At this point, the length of the properties is known and is stored in value_properties_length.
+		// This reads the entire properties out of the tvb and into a buffer (buf).
+		guint8* buf = tvb_get_string_enc(wmem_packet_scope(), tvb_to_use, offset, (gint) value_properties_length, ENC_UTF_8);
+
+		// "Profile\0subChanges\0continuous\0true\0foo\0bar" -> "Profile:subChanges:continuous:true:foo:bar"
+		// Iterate over buf and change all the \0 null characters to ':', since otherwise trying to set a header
+		// field to this buffer via proto_tree_add_item() will end up only printing it up to the first null character,
+		// for example "Profile", even though there are many more properties that follow.
+		for (int i = 0; i < (int) value_properties_length; i++) {
+			if (i < (int) (value_properties_length - 1)) {
+				if (buf[i] == '\0') {  // TODO: I don't even know if this is actually a safe assumption in a UTF-8 encoded string
+					buf[i] = ':';
+				}
+			}
+		}
+
+		if(value_properties_length > 0) {
+			proto_tree_add_string(blip_tree, hf_blip_properties, tvb_to_use, offset, (int)value_properties_length, (const char *)buf);
+		}
+
+		// Bump the offset by the length of the properties
+		offset += (gint)value_properties_length;
+	}
+
+	// ------------------------ BLIP Frame: Message Body --------------------------------------------------
+
+	// WS_DLL_PUBLIC gint tvb_reported_length_remaining(const tvbuff_t *tvb, const gint offset);
+	gint reported_length_remaining = tvb_reported_length_remaining(tvb_to_use, offset);
+
+	// Don't read in the trailing checksum at the end
+	if (!compressed && reported_length_remaining >= BLIP_BODY_CHECKSUM_SIZE) {
+		reported_length_remaining -= BLIP_BODY_CHECKSUM_SIZE;
+	}
+
+	if(reported_length_remaining > 0) {
+		proto_tree_add_item(blip_tree, hf_blip_message_body, tvb_to_use, offset, reported_length_remaining, ENC_UTF_8|ENC_NA);
+	}
+
+	offset += reported_length_remaining;
+	proto_tree_add_item(blip_tree, hf_blip_checksum, tvb, tvb_reported_length(tvb) - BLIP_BODY_CHECKSUM_SIZE, BLIP_BODY_CHECKSUM_SIZE, ENC_BIG_ENDIAN);
+
+	// -------------------------------------------- Etc ----------------------------------------------------------------
+
+	return tvb_captured_length(tvb);
+}
+
+void
+proto_register_blip(void)
+{
+	static hf_register_info hf[] = {
+	{ &hf_blip_message_number,
+		{ "Message Number", "blip.messagenum", FT_UINT64, BASE_DEC,
+			NULL, 0x0, NULL, HFILL }
+	},
+	{ &hf_blip_frame_flags,
+		{ "Frame Flags", "blip.frameflags", FT_UINT8, BASE_HEX | BASE_EXT_STRING,
+			&flag_combos_ext, 0x0, NULL, HFILL }
+	},
+	{ &hf_blip_properties_length,
+		{ "Properties Length", "blip.propslength", FT_UINT64, BASE_DEC,
+			NULL, 0x0, NULL, HFILL }
+	},
+	{ &hf_blip_properties,
+		{ "Properties", "blip.props", FT_STRING, STR_UNICODE,
+			NULL, 0x0, NULL, HFILL }
+		},
+	{ &hf_blip_message_body,
+		{ "Message Body", "blip.messagebody", FT_STRING, STR_UNICODE,
+			NULL, 0x0, NULL, HFILL }
+	},
+	{ &hf_blip_ack_size,
+		{ "ACK num bytes", "blip.numackbytes", FT_UINT64, BASE_DEC,
+			NULL, 0x0, NULL, HFILL }
+	},
+	{ &hf_blip_checksum,
+		{ "Checksum", "blip.checksum", FT_UINT32, BASE_DEC,
+			NULL, 0x0, NULL, HFILL }
+	}
+	};
+
+	/* Setup protocol subtree array */
+	static gint *ett[] = {
+		&ett_blip
+	};
+
+	proto_blip = proto_register_protocol("BLIP Couchbase Mobile", "BLIP", "blip");
+
+	proto_register_field_array(proto_blip, hf, array_length(hf));
+	proto_register_subtree_array(ett, array_length(ett));
+
+	blip_handle = register_dissector("blip", dissect_blip, proto_blip);
+}
+
+void
+proto_reg_handoff_blip(void)
+{
+
+	// Register the blip dissector as a subprotocol dissector of "ws.protocol",
+	// matching any packets with a Web-Sec-Protocol header of "BLIP_3+CBMobile_2".
+	//
+	// See https://github.com/couchbase/sync_gateway/issues/3356#issuecomment-370958321 for
+	// more notes on how the websocket dissector routes packets down to subprotocol handlers.
+
+	dissector_add_string("ws.protocol", "BLIP_3+CBMobile_2", blip_handle);
+}
+
+/*
+ * Editor modelines
+ *
+ * Local Variables:
+ * c-basic-offset: 2
+ * tab-width: 8
+ * indent-tabs-mode: nil
+ * End:
+ *
+ * ex: set shiftwidth=2 tabstop=8 expandtab:
+ * :indentSize=2:tabSize=8:noTabs=true:
+ */