Babel: Refactor TLV parsing code for easier reuse (69d10132) · Commits · 戴 / Bird

proto/babel/packets.c

+107 −64

Original line number	Diff line number	Diff line
		@@ -120,8 +120,19 @@ struct babel_subtlv_source_prefix {
		#define BABEL_UF_DEF_PREFIX 0x80
		#define BABEL_UF_ROUTER_ID 0x40

		struct babel_parse_state;
		struct babel_write_state;

		struct babel_tlv_data {
		u8 min_length;
		int (read_tlv)(struct babel_tlv hdr, union babel_msg m, struct babel_parse_state state);
		uint (write_tlv)(struct babel_tlv hdr, union babel_msg m, struct babel_write_state state, uint max_len);
		void (handle_tlv)(union babel_msg m, struct babel_iface *ifa);
		};

		struct babel_parse_state {
		const struct babel_tlv_data* (*get_tlv_data)(u8 type);
		const struct babel_tlv_data* (*get_subtlv_data)(u8 type);
		struct babel_proto *proto;
		struct babel_iface *ifa;
		ip_addr saddr;
		@@ -167,6 +178,37 @@ struct babel_write_state {

		#define NET_SIZE(n) BYTES(net_pxlen(n))


		/* Helper macros to loop over a series of TLVs.
		* @start pointer to first TLV (void * or struct babel_tlv *)
		* @end byte * pointer to TLV stream end
		* @tlv struct babel_tlv pointer used as iterator
		* @frame_err boolean (u8) that will be set to 1 if a frame error occurred
		* @saddr source addr for use in log output
		* @ifname ifname for use in log output
		*/
		#define WALK_TLVS(start, end, tlv, frame_err, saddr, ifname) \
		for (tlv = start; \
		(byte *)tlv < end; \
		tlv = NEXT_TLV(tlv)) \
		{ \
		byte *loop_pos; \
		/* Ugly special case */ \
		if (tlv->type == BABEL_TLV_PAD1) \
		continue; \
		\
		/* The end of the common TLV header */ \
		loop_pos = (byte *)tlv + sizeof(struct babel_tlv); \
		if ((loop_pos > end) \|\| (loop_pos + tlv->length > end)) \
		{ \
		LOG_PKT("Bad TLV from %I via %s type %d pos %d - framing error", \
		saddr, ifname, tlv->type, (byte )tlv - (byte )start); \
		frame_err = 1; \
		break; \
		}

		#define WALK_TLVS_END }

		static inline uint
		bytes_equal(u8 b1, u8 b2, uint maxlen)
		{
		@@ -255,13 +297,6 @@ static uint babel_write_route_request(struct babel_tlv hdr, union babel_msg ms
		static uint babel_write_seqno_request(struct babel_tlv hdr, union babel_msg msg, struct babel_write_state *state, uint max_len);
		static int babel_write_source_prefix(struct babel_tlv hdr, net_addr net, uint max_len);

		struct babel_tlv_data {
		u8 min_length;
		int (read_tlv)(struct babel_tlv hdr, union babel_msg m, struct babel_parse_state state);
		uint (write_tlv)(struct babel_tlv hdr, union babel_msg m, struct babel_write_state state, uint max_len);
		void (handle_tlv)(union babel_msg m, struct babel_iface *ifa);
		};

		static const struct babel_tlv_data tlv_data[BABEL_TLV_MAX] = {
		[BABEL_TLV_ACK_REQ] = {
		sizeof(struct babel_tlv_ack_req),
		@@ -319,6 +354,30 @@ static const struct babel_tlv_data tlv_data[BABEL_TLV_MAX] = {
		},
		};

		static const struct babel_tlv_data *get_packet_tlv_data(u8 type)
		{
		return type < sizeof(tlv_data) / sizeof(*tlv_data) ? &tlv_data[type] : NULL;
		}

		static const struct babel_tlv_data source_prefix_tlv_data = {
		sizeof(struct babel_subtlv_source_prefix),
		babel_read_source_prefix,
		NULL,
		NULL
		};

		static const struct babel_tlv_data *get_packet_subtlv_data(u8 type)
		{
		switch(type)
		{
		case BABEL_SUBTLV_SOURCE_PREFIX:
		return &source_prefix_tlv_data;

		default:
		return NULL;
		}
		}

		static int
		babel_read_ack_req(struct babel_tlv hdr, union babel_msg m,
		struct babel_parse_state *state)
		@@ -1083,69 +1142,65 @@ babel_write_source_prefix(struct babel_tlv hdr, net_addr n, uint max_len)
		return len;
		}


		static inline int
		babel_read_subtlvs(struct babel_tlv *hdr,
		union babel_msg *msg,
		struct babel_parse_state *state)
		{
		const struct babel_tlv_data *tlv_data;
		struct babel_proto *p = state->proto;
		struct babel_tlv *tlv;
		byte pos, end = (byte *) hdr + TLV_LENGTH(hdr);
		byte end = (byte ) hdr + TLV_LENGTH(hdr);
		u8 frame_err = 0;
		int res;

		for (tlv = (void *) hdr + state->current_tlv_endpos;
		(byte *) tlv < end;
		tlv = NEXT_TLV(tlv))
		WALK_TLVS((void *)hdr + state->current_tlv_endpos, end, tlv, frame_err,
		state->saddr, state->ifa->ifname)
		{
		/* Ugly special case */
		if (tlv->type == BABEL_TLV_PAD1)
		if (tlv->type == BABEL_SUBTLV_PADN)
		continue;

		/* The end of the common TLV header */
		pos = (byte *)tlv + sizeof(struct babel_tlv);
		if ((pos > end) \|\| (pos + tlv->length > end))
		return PARSE_ERROR;

		/*
		* The subtlv type space is non-contiguous (due to the mandatory bit), so
		* use a switch for dispatch instead of the mapping array we use for TLVs
		*/
		switch (tlv->type)
		if (!state->get_subtlv_data \|\|
		!(tlv_data = state->get_subtlv_data(tlv->type)) \|\|
		!tlv_data->read_tlv)
		{
		case BABEL_SUBTLV_SOURCE_PREFIX:
		res = babel_read_source_prefix(tlv, msg, state);
		if (res != PARSE_SUCCESS)
		return res;
		break;

		case BABEL_SUBTLV_PADN:
		default:
		/* Unknown mandatory subtlv; PARSE_IGNORE ignores the whole TLV */
		if (tlv->type >= 128)
		return PARSE_IGNORE;
		break;
		continue;
		}

		res = tlv_data->read_tlv(tlv, msg, state);
		if (res != PARSE_SUCCESS)
		return res;
		}
		WALK_TLVS_END;

		return PARSE_SUCCESS;
		return frame_err ? PARSE_ERROR : PARSE_SUCCESS;
		}

		static inline int
		static int
		babel_read_tlv(struct babel_tlv *hdr,
		union babel_msg *msg,
		struct babel_parse_state *state)
		{
		const struct babel_tlv_data *tlv_data;

		if ((hdr->type <= BABEL_TLV_PADN) \|\|
		(hdr->type >= BABEL_TLV_MAX) \|\|
		!tlv_data[hdr->type].read_tlv)
		(hdr->type >= BABEL_TLV_MAX))
		return PARSE_IGNORE;

		tlv_data = state->get_tlv_data(hdr->type);

		if (!tlv_data \|\| !tlv_data->read_tlv)
		return PARSE_IGNORE;

		if (TLV_LENGTH(hdr) < tlv_data[hdr->type].min_length)
		if (TLV_LENGTH(hdr) < tlv_data->min_length)
		return PARSE_ERROR;

		state->current_tlv_endpos = tlv_data[hdr->type].min_length;
		state->current_tlv_endpos = tlv_data->min_length;

		int res = tlv_data[hdr->type].read_tlv(hdr, msg, state);
		int res = tlv_data->read_tlv(hdr, msg, state);
		if (res != PARSE_SUCCESS)
		return res;

		@@ -1330,6 +1385,7 @@ static void
		babel_process_packet(struct babel_pkt_header *pkt, int len,
		ip_addr saddr, struct babel_iface *ifa)
		{
		u8 frame_err UNUSED = 0;
		struct babel_proto *p = ifa->proto;
		struct babel_tlv *tlv;
		struct babel_msg_node *msg;
		@@ -1337,10 +1393,11 @@ babel_process_packet(struct babel_pkt_header *pkt, int len,
		int res;

		int plen = sizeof(struct babel_pkt_header) + get_u16(&pkt->length);
		byte *pos;
		byte end = (byte )pkt + plen;

		struct babel_parse_state state = {
		.get_tlv_data = &get_packet_tlv_data,
		.get_subtlv_data = &get_packet_subtlv_data,
		.proto = p,
		.ifa = ifa,
		.saddr = saddr,
		@@ -1369,23 +1426,8 @@ babel_process_packet(struct babel_pkt_header *pkt, int len,

		/* First pass through the packet TLV by TLV, parsing each into internal data
		structures. */
		for (tlv = FIRST_TLV(pkt);
		(byte *)tlv < end;
		tlv = NEXT_TLV(tlv))
		WALK_TLVS(FIRST_TLV(pkt), end, tlv, frame_err, saddr, ifa->iface->name)
		{
		/* Ugly special case */
		if (tlv->type == BABEL_TLV_PAD1)
		continue;

		/* The end of the common TLV header */
		pos = (byte *)tlv + sizeof(struct babel_tlv);
		if ((pos > end) \|\| (pos + tlv->length > end))
		{
		LOG_PKT("Bad TLV from %I via %s type %d pos %d - framing error",
		saddr, ifa->iface->name, tlv->type, (byte )tlv - (byte )pkt);
		break;
		}

		msg = sl_allocz(p->msg_slab);
		res = babel_read_tlv(tlv, &msg->msg, &state);
		if (res == PARSE_SUCCESS)
		@@ -1405,8 +1447,9 @@ babel_process_packet(struct babel_pkt_header *pkt, int len,
		break;
		}
		}
		WALK_TLVS_END;

		/* Parsing done, handle all parsed TLVs */
		/* Parsing done, handle all parsed TLVs, regardless of any errors */
		WALK_LIST_FIRST(msg, msgs)
		{
		if (tlv_data[msg->msg.type].handle_tlv)

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