net: tcp: Add support for TCP options parsing (cdea2bfa) · Commits · Wenxi XU / zephyr

subsys/net/ip/net_context.c

+14 −2

Original line number	Diff line number	Diff line
		@@ -1613,10 +1613,22 @@ NET_CONN_CB(tcp_syn_rcvd)
		*/
		if (NET_TCP_FLAGS(tcp_hdr) == NET_TCP_SYN) {
		int r;
		u16_t send_mss = NET_TCP_DEFAULT_MSS;
		int opt_totlen;
		struct net_tcp_options tcp_opts = {
		.mss = NET_TCP_DEFAULT_MSS,
		};

		net_tcp_print_recv_info("SYN", pkt, tcp_hdr->src_port);

		opt_totlen = NET_TCP_HDR_LEN(tcp_hdr)
		- sizeof(struct net_tcp_hdr);
		/* We expect MSS option to be present (opt_totlen > 0),
		* so call unconditionally.
		*/
		if (net_tcp_parse_opts(pkt, opt_totlen, &tcp_opts) < 0) {
		return NET_DROP;
		}

		net_tcp_change_state(tcp, NET_TCP_SYN_RCVD);

		/* Set TCP seq and ack which are then stored in the backlog */
		@@ -1627,7 +1639,7 @@ NET_CONN_CB(tcp_syn_rcvd)

		/* Get MSS from TCP options here*/

		r = tcp_backlog_syn(pkt, context, send_mss);
		r = tcp_backlog_syn(pkt, context, tcp_opts.mss);
		if (r < 0) {
		if (r == -EADDRINUSE) {
		NET_DBG("TCP connection already exists");

subsys/net/ip/tcp.c

+77 −2

Original line number	Diff line number	Diff line
		@@ -600,7 +600,7 @@ u16_t net_tcp_get_recv_mss(const struct net_tcp *tcp)
		static void net_tcp_set_syn_opt(struct net_tcp tcp, u8_t options,
		u8_t *optionlen)
		{
		u16_t recv_mss;
		u32_t recv_mss;

		*optionlen = 0;

		@@ -611,7 +611,8 @@ static void net_tcp_set_syn_opt(struct net_tcp tcp, u8_t options,
		recv_mss = 0;
		}

		UNALIGNED_PUT(htonl((u32_t)recv_mss \| NET_TCP_MSS_HEADER),
		recv_mss \|= (NET_TCP_MSS_OPT << 24) \| (NET_TCP_MSS_SIZE << 16);
		UNALIGNED_PUT(htonl(recv_mss),
		(u32_t )(options + optionlen));

		*optionlen += NET_TCP_MSS_SIZE;
		@@ -1235,3 +1236,77 @@ struct net_buf net_tcp_set_chksum(struct net_pkt pkt, struct net_buf *frag)

		return frag;
		}

		int net_tcp_parse_opts(struct net_pkt *pkt, int opt_totlen,
		struct net_tcp_options *opts)
		{
		struct net_buf *frag = pkt->frags;
		u16_t pos = net_pkt_ip_hdr_len(pkt)
		+ net_pkt_ipv6_ext_len(pkt)
		+ sizeof(struct net_tcp_hdr);
		u8_t opt, optlen;

		/* TODO: this should be done for each TCP pkt, on reception */
		if (pos + opt_totlen > net_pkt_get_len(pkt)) {
		NET_ERR("Truncated pkt len: %d, expected: %d",
		(int)net_pkt_get_len(pkt), pos + opt_totlen);
		return -EINVAL;
		}

		while (opt_totlen) {
		frag = net_frag_read(frag, pos, &pos, sizeof(opt), &opt);
		opt_totlen--;

		/* https://www.iana.org/assignments/tcp-parameters/tcp-parameters.xhtml#tcp-parameters-1 */
		/* "Options 0 and 1 are exactly one octet which is their
		* kind field. All other options have their one octet
		* kind field, followed by a one octet length field,
		* followed by length-2 octets of option data."
		*/
		if (opt == NET_TCP_END_OPT) {
		break;
		} else if (opt == NET_TCP_NOP_OPT) {
		continue;
		}

		if (!opt_totlen) {
		optlen = 0;
		goto error;
		}

		frag = net_frag_read(frag, pos, &pos, sizeof(optlen), &optlen);
		opt_totlen--;
		if (optlen < 2) {
		goto error;
		}

		/* Subtract opt/optlen size now to avoid doing this
		* repeatedly.
		*/
		optlen -= 2;
		if (opt_totlen < optlen) {
		goto error;
		}

		switch (opt) {
		case NET_TCP_MSS_OPT:
		if (optlen != 2) {
		goto error;
		}
		frag = net_frag_read(frag, pos, &pos,
		optlen, (u8_t *)&opts->mss);
		break;
		default:
		frag = net_frag_skip(frag, pos, &pos, optlen);
		break;
		}

		opt_totlen -= optlen;
		}

		return 0;

		error:
		NET_ERR("Invalid TCP opt: %d len: %d", opt, optlen);
		return -EINVAL;
		}

subsys/net/ip/tcp.h

+33 −5

Original line number	Diff line number	Diff line
		@@ -89,11 +89,22 @@ enum net_tcp_state {

		#define NET_TCP_MAX_OPT_SIZE 8

		#define NET_TCP_MSS_HEADER 0x02040000 /* MSS option */
		#define NET_TCP_WINDOW_HEADER 0x30300 /* Window scale option */

		#define NET_TCP_MSS_SIZE 4 /* MSS option size */
		#define NET_TCP_WINDOW_SIZE 3 /* Window scale option size */
		/* TCP Option codes */
		#define NET_TCP_END_OPT 0
		#define NET_TCP_NOP_OPT 1
		#define NET_TCP_MSS_OPT 2
		#define NET_TCP_WINDOW_SCALE_OPT 3

		/* TCP Option sizes */
		#define NET_TCP_END_SIZE 1
		#define NET_TCP_NOP_SIZE 1
		#define NET_TCP_MSS_SIZE 4
		#define NET_TCP_WINDOW_SCALE_SIZE 3

		/** Parsed TCP option values for net_tcp_parse_opts() */
		struct net_tcp_options {
		u16_t mss;
		};

		/* Max received bytes to buffer internally */
		#define NET_TCP_BUF_MAX_LEN 1280
		@@ -443,6 +454,23 @@ struct net_buf net_tcp_set_chksum(struct net_pkt pkt, struct net_buf *frag);
		*/
		u16_t net_tcp_get_chksum(struct net_pkt pkt, struct net_buf frag);

		/**
		* @brief Parse TCP options from network packet.
		*
		* Parse TCP options, returning MSS value (as that the only one we
		* handle so far).
		*
		* @param pkt Network packet
		* @param opt_totlen Total length of options to parse
		* @param opts Pointer to TCP options structure. (Each option is updated
		* only if present, so the structure must be initialized with the default
		* values.)
		*
		* @return 0 if no error, <0 in case of error
		*/
		int net_tcp_parse_opts(struct net_pkt *pkt, int opt_totlen,
		struct net_tcp_options *opts);

		#else

		static inline u16_t net_tcp_get_chksum(struct net_pkt *pkt,

Admin message