net: support being a TCP server to unblock TCP fastboot

Make following changes to unblock TCP fastboot support:

1. Implement being a TCP server support
2. Introduce dedicated TCP traffic handler (get rid of UDP signature)
3. Ensure seq_num and ack_num are respected in net_send_tcp_packet
function (make sure existing wget_cmd code is reflected with the fix)

Signed-off-by: Dmitrii Merkurev <dimorinny@google.com>
Cc: Ying-Chun Liu (PaulLiu) <paul.liu@linaro.org>
Cc: Simon Glass <sjg@chromium.org>
Сс: Joe Hershberger <joe.hershberger@ni.com>
Сс: Ramon Fried <rfried.dev@gmail.com>
Reviewed-by: Ying-Chun Liu (PaulLiu) <paul.liu@linaro.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Ramon Fried <rfried.dev@gmail.com>
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 3225516..c29d4ce 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -259,6 +259,7 @@
  * enum tcp_state - TCP State machine states for connection
  * @TCP_CLOSED: Need to send SYN to connect
  * @TCP_SYN_SENT: Trying to connect, waiting for SYN ACK
+ * @TCP_SYN_RECEIVED: Initial SYN received, waiting for ACK
  * @TCP_ESTABLISHED: both server & client have a connection
  * @TCP_CLOSE_WAIT: Rec FIN, passed to app for FIN, ACK rsp
  * @TCP_CLOSING: Rec FIN, sent FIN, ACK waiting for ACK
@@ -268,6 +269,7 @@
 enum tcp_state {
 	TCP_CLOSED,
 	TCP_SYN_SENT,
+	TCP_SYN_RECEIVED,
 	TCP_ESTABLISHED,
 	TCP_CLOSE_WAIT,
 	TCP_CLOSING,
@@ -283,14 +285,18 @@
 /**
  * rxhand_tcp() - An incoming packet handler.
  * @pkt: pointer to the application packet
- * @dport: destination UDP port
+ * @dport: destination TCP port
  * @sip: source IP address
- * @sport: source UDP port
+ * @sport: source TCP port
+ * @tcp_seq_num: TCP sequential number
+ * @tcp_ack_num: TCP acknowledgment number
+ * @action: TCP action (SYN, ACK, FIN, etc)
  * @len: packet length
  */
-typedef void rxhand_tcp(uchar *pkt, unsigned int dport,
-			struct in_addr sip, unsigned int sport,
-			unsigned int len);
+typedef void rxhand_tcp(uchar *pkt, u16 dport,
+			struct in_addr sip, u16 sport,
+			u32 tcp_seq_num, u32 tcp_ack_num,
+			u8 action, unsigned int len);
 void tcp_set_tcp_handler(rxhand_tcp *f);
 
 void rxhand_tcp_f(union tcp_build_pkt *b, unsigned int len);
diff --git a/net/tcp.c b/net/tcp.c
index 8d338c7..a713e1d 100644
--- a/net/tcp.c
+++ b/net/tcp.c
@@ -36,7 +36,6 @@
 
 static u32 tcp_seq_init;
 static u32 tcp_ack_edge;
-static u32 tcp_seq_max;
 
 static int tcp_activity_count;
 
@@ -90,9 +89,10 @@
 	current_tcp_state = new_state;
 }
 
-static void dummy_handler(uchar *pkt, unsigned int dport,
-			  struct in_addr sip, unsigned int sport,
-			  unsigned int len)
+static void dummy_handler(uchar *pkt, u16 dport,
+			  struct in_addr sip, u16 sport,
+			  u32 tcp_seq_num, u32 tcp_ack_num,
+			  u8 action, unsigned int len)
 {
 }
 
@@ -256,7 +256,7 @@
 	switch (action) {
 	case TCP_SYN:
 		debug_cond(DEBUG_DEV_PKT,
-			   "TCP Hdr:SYN (%pI4, %pI4, sq=%d, ak=%d)\n",
+			   "TCP Hdr:SYN (%pI4, %pI4, sq=%u, ak=%u)\n",
 			   &net_server_ip, &net_ip,
 			   tcp_seq_num, tcp_ack_num);
 		tcp_activity_count = 0;
@@ -271,41 +271,46 @@
 			current_tcp_state = TCP_SYN_SENT;
 		}
 		break;
+	case TCP_SYN | TCP_ACK:
 	case TCP_ACK:
 		pkt_hdr_len = IP_HDR_SIZE + net_set_ack_options(b);
 		b->ip.hdr.tcp_flags = action;
 		debug_cond(DEBUG_DEV_PKT,
-			   "TCP Hdr:ACK (%pI4, %pI4, s=%d, a=%d, A=%x)\n",
+			   "TCP Hdr:ACK (%pI4, %pI4, s=%u, a=%u, A=%x)\n",
 			   &net_server_ip, &net_ip, tcp_seq_num, tcp_ack_num,
 			   action);
 		break;
 	case TCP_FIN:
 		debug_cond(DEBUG_DEV_PKT,
-			   "TCP Hdr:FIN  (%pI4, %pI4, s=%d, a=%d)\n",
+			   "TCP Hdr:FIN  (%pI4, %pI4, s=%u, a=%u)\n",
 			   &net_server_ip, &net_ip, tcp_seq_num, tcp_ack_num);
 		payload_len = 0;
 		pkt_hdr_len = IP_TCP_HDR_SIZE;
 		current_tcp_state = TCP_FIN_WAIT_1;
 		break;
-
+	case TCP_RST | TCP_ACK:
+	case TCP_RST:
+		debug_cond(DEBUG_DEV_PKT,
+			   "TCP Hdr:RST  (%pI4, %pI4, s=%u, a=%u)\n",
+			   &net_server_ip, &net_ip, tcp_seq_num, tcp_ack_num);
+		current_tcp_state = TCP_CLOSED;
+		break;
 	/* Notify connection closing */
-
 	case (TCP_FIN | TCP_ACK):
 	case (TCP_FIN | TCP_ACK | TCP_PUSH):
 		if (current_tcp_state == TCP_CLOSE_WAIT)
 			current_tcp_state = TCP_CLOSING;
 
-		tcp_ack_edge++;
 		debug_cond(DEBUG_DEV_PKT,
-			   "TCP Hdr:FIN ACK PSH(%pI4, %pI4, s=%d, a=%d, A=%x)\n",
+			   "TCP Hdr:FIN ACK PSH(%pI4, %pI4, s=%u, a=%u, A=%x)\n",
 			   &net_server_ip, &net_ip,
-			   tcp_seq_num, tcp_ack_edge, action);
+			   tcp_seq_num, tcp_ack_num, action);
 		fallthrough;
 	default:
 		pkt_hdr_len = IP_HDR_SIZE + net_set_ack_options(b);
 		b->ip.hdr.tcp_flags = action | TCP_PUSH | TCP_ACK;
 		debug_cond(DEBUG_DEV_PKT,
-			   "TCP Hdr:dft  (%pI4, %pI4, s=%d, a=%d, A=%x)\n",
+			   "TCP Hdr:dft  (%pI4, %pI4, s=%u, a=%u, A=%x)\n",
 			   &net_server_ip, &net_ip,
 			   tcp_seq_num, tcp_ack_num, action);
 	}
@@ -313,12 +318,12 @@
 	pkt_len	= pkt_hdr_len + payload_len;
 	tcp_len	= pkt_len - IP_HDR_SIZE;
 
+	tcp_ack_edge = tcp_ack_num;
 	/* TCP Header */
 	b->ip.hdr.tcp_ack = htonl(tcp_ack_edge);
 	b->ip.hdr.tcp_src = htons(sport);
 	b->ip.hdr.tcp_dst = htons(dport);
 	b->ip.hdr.tcp_seq = htonl(tcp_seq_num);
-	tcp_seq_num = tcp_seq_num + payload_len;
 
 	/*
 	 * TCP window size - TCP header variable tcp_win.
@@ -353,9 +358,8 @@
  * tcp_hole() - Selective Acknowledgment (Essential for fast stream transfer)
  * @tcp_seq_num: TCP sequence start number
  * @len: the length of sequence numbers
- * @tcp_seq_max: maximum of sequence numbers
  */
-void tcp_hole(u32 tcp_seq_num, u32 len, u32 tcp_seq_max)
+void tcp_hole(u32 tcp_seq_num, u32 len)
 {
 	u32 idx_sack, sack_in;
 	u32 sack_end = TCP_SACK - 1;
@@ -496,7 +500,7 @@
 	}
 }
 
-static u8 tcp_state_machine(u8 tcp_flags, u32 *tcp_seq_num, int payload_len)
+static u8 tcp_state_machine(u8 tcp_flags, u32 tcp_seq_num, int payload_len)
 {
 	u8 tcp_fin = tcp_flags & TCP_FIN;
 	u8 tcp_syn = tcp_flags & TCP_SYN;
@@ -527,46 +531,44 @@
 	switch  (current_tcp_state) {
 	case TCP_CLOSED:
 		debug_cond(DEBUG_INT_STATE, "TCP CLOSED %x\n", tcp_flags);
-		if (tcp_ack)
-			action = TCP_DATA;
-		else if (tcp_syn)
-			action = TCP_RST;
-		else if (tcp_fin)
+		if (tcp_syn) {
+			action = TCP_SYN | TCP_ACK;
+			tcp_seq_init = tcp_seq_num;
+			tcp_ack_edge = tcp_seq_num + 1;
+			current_tcp_state = TCP_SYN_RECEIVED;
+		} else if (tcp_ack || tcp_fin) {
 			action = TCP_DATA;
+		}
 		break;
+	case TCP_SYN_RECEIVED:
 	case TCP_SYN_SENT:
-		debug_cond(DEBUG_INT_STATE, "TCP_SYN_SENT %x, %d\n",
-			   tcp_flags, *tcp_seq_num);
+		debug_cond(DEBUG_INT_STATE, "TCP_SYN_SENT | TCP_SYN_RECEIVED %x, %u\n",
+			   tcp_flags, tcp_seq_num);
 		if (tcp_fin) {
 			action = action | TCP_PUSH;
 			current_tcp_state = TCP_CLOSE_WAIT;
-		}
-		if (tcp_syn) {
-			action = action | TCP_ACK | TCP_PUSH;
-			if (tcp_ack) {
-				tcp_seq_init = *tcp_seq_num;
-				*tcp_seq_num = *tcp_seq_num + 1;
-				tcp_seq_max = *tcp_seq_num;
-				tcp_ack_edge = *tcp_seq_num;
-				sack_idx = 0;
-				edge_a[sack_idx].se.l = *tcp_seq_num;
-				edge_a[sack_idx].se.r = *tcp_seq_num;
-				prev_len = 0;
-				current_tcp_state = TCP_ESTABLISHED;
-				for (i = 0; i < TCP_SACK; i++)
-					edge_a[i].st = NOPKT;
-			}
-		} else if (tcp_ack) {
+		} else if (tcp_ack || (tcp_syn && tcp_ack)) {
+			action |= TCP_ACK;
+			tcp_seq_init = tcp_seq_num;
+			tcp_ack_edge = tcp_seq_num + 1;
+			sack_idx = 0;
+			edge_a[sack_idx].se.l = tcp_ack_edge;
+			edge_a[sack_idx].se.r = tcp_ack_edge;
+			prev_len = 0;
+			current_tcp_state = TCP_ESTABLISHED;
+			for (i = 0; i < TCP_SACK; i++)
+				edge_a[i].st = NOPKT;
+
+			if (tcp_syn && tcp_ack)
+				action |= TCP_PUSH;
+		} else {
 			action = TCP_DATA;
 		}
-
 		break;
 	case TCP_ESTABLISHED:
 		debug_cond(DEBUG_INT_STATE, "TCP_ESTABLISHED %x\n", tcp_flags);
-		if (*tcp_seq_num > tcp_seq_max)
-			tcp_seq_max = *tcp_seq_num;
 		if (payload_len > 0) {
-			tcp_hole(*tcp_seq_num, payload_len, tcp_seq_max);
+			tcp_hole(tcp_seq_num, payload_len);
 			tcp_fin = TCP_DATA;  /* cause standalone FIN */
 		}
 
@@ -603,15 +605,14 @@
 	case TCP_FIN_WAIT_1:
 		debug_cond(DEBUG_INT_STATE, "TCP_FIN_WAIT_1 (%x)\n", tcp_flags);
 		if (tcp_fin) {
+			tcp_ack_edge++;
 			action = TCP_ACK | TCP_FIN;
 			current_tcp_state = TCP_FIN_WAIT_2;
 		}
 		if (tcp_syn)
 			action = TCP_RST;
-		if (tcp_ack) {
+		if (tcp_ack)
 			current_tcp_state = TCP_CLOSED;
-			tcp_seq_num = tcp_seq_num + 1;
-		}
 		break;
 	case TCP_CLOSING:
 		debug_cond(DEBUG_INT_STATE, "TCP_CLOSING (%x)\n", tcp_flags);
@@ -640,7 +641,6 @@
 	u16 tcp_rx_xsum = b->ip.hdr.ip_sum;
 	u8  tcp_action = TCP_DATA;
 	u32 tcp_seq_num, tcp_ack_num;
-	struct in_addr action_and_state;
 	int tcp_hdr_len, payload_len;
 
 	/* Verify IP header */
@@ -685,7 +685,7 @@
 
 	/* Packets are not ordered. Send to app as received. */
 	tcp_action = tcp_state_machine(b->ip.hdr.tcp_flags,
-				       &tcp_seq_num, payload_len);
+				       tcp_seq_num, payload_len);
 
 	tcp_activity_count++;
 	if (tcp_activity_count > TCP_ACTIVITY) {
@@ -695,18 +695,17 @@
 
 	if ((tcp_action & TCP_PUSH) || payload_len > 0) {
 		debug_cond(DEBUG_DEV_PKT,
-			   "TCP Notify (action=%x, Seq=%d,Ack=%d,Pay%d)\n",
+			   "TCP Notify (action=%x, Seq=%u,Ack=%u,Pay%d)\n",
 			   tcp_action, tcp_seq_num, tcp_ack_num, payload_len);
 
-		action_and_state.s_addr = tcp_action;
-		(*tcp_packet_handler) ((uchar *)b + pkt_len - payload_len,
-				       tcp_seq_num, action_and_state,
-				       tcp_ack_num, payload_len);
+		(*tcp_packet_handler) ((uchar *)b + pkt_len - payload_len, b->ip.hdr.tcp_dst,
+				       b->ip.hdr.ip_src, b->ip.hdr.tcp_src, tcp_seq_num,
+				       tcp_ack_num, tcp_action, payload_len);
 
 	} else if (tcp_action != TCP_DATA) {
 		debug_cond(DEBUG_DEV_PKT,
-			   "TCP Action (action=%x,Seq=%d,Ack=%d,Pay=%d)\n",
-			   tcp_action, tcp_seq_num, tcp_ack_num, payload_len);
+			   "TCP Action (action=%x,Seq=%u,Ack=%u,Pay=%d)\n",
+			   tcp_action, tcp_ack_num, tcp_ack_edge, payload_len);
 
 		/*
 		 * Warning: Incoming Ack & Seq sequence numbers are transposed
@@ -715,6 +714,6 @@
 		net_send_tcp_packet(0, ntohs(b->ip.hdr.tcp_src),
 				    ntohs(b->ip.hdr.tcp_dst),
 				    (tcp_action & (~TCP_PUSH)),
-				    tcp_seq_num, tcp_ack_num);
+				    tcp_ack_num, tcp_ack_edge);
 	}
 }
diff --git a/net/wget.c b/net/wget.c
index eebdf80..2dbfeb1 100644
--- a/net/wget.c
+++ b/net/wget.c
@@ -88,8 +88,8 @@
 {
 	u8 action = retry_action;
 	int len = retry_len;
-	unsigned int tcp_ack_num = retry_tcp_ack_num + len;
-	unsigned int tcp_seq_num = retry_tcp_seq_num;
+	unsigned int tcp_ack_num = retry_tcp_seq_num + (len == 0 ? 1 : len);
+	unsigned int tcp_seq_num = retry_tcp_ack_num;
 	uchar *ptr, *offset;
 
 	switch (current_wget_state) {
@@ -130,8 +130,8 @@
 	}
 }
 
-static void wget_send(u8 action, unsigned int tcp_ack_num,
-		      unsigned int tcp_seq_num, int len)
+static void wget_send(u8 action, unsigned int tcp_seq_num,
+		      unsigned int tcp_ack_num, int len)
 {
 	retry_action = action;
 	retry_tcp_ack_num = tcp_ack_num;
@@ -178,10 +178,8 @@
 #define PKT_QUEUE_PACKET_SIZE 0x800
 
 static void wget_connected(uchar *pkt, unsigned int tcp_seq_num,
-			   struct in_addr action_and_state,
-			   unsigned int tcp_ack_num, unsigned int len)
+			   u8 action, unsigned int tcp_ack_num, unsigned int len)
 {
-	u8 action = action_and_state.s_addr;
 	uchar *pkt_in_q;
 	char *pos;
 	int hlen, i;
@@ -268,22 +266,25 @@
 }
 
 /**
- * wget_handler() - handler of wget
- * @pkt: the pointer to the payload
- * @tcp_seq_num: tcp sequence number
- * @action_and_state: TCP state
- * @tcp_ack_num: tcp acknowledge number
- * @len: length of the payload
+ * wget_handler() - TCP handler of wget
+ * @pkt: pointer to the application packet
+ * @dport: destination TCP port
+ * @sip: source IP address
+ * @sport: source TCP port
+ * @tcp_seq_num: TCP sequential number
+ * @tcp_ack_num: TCP acknowledgment number
+ * @action: TCP action (SYN, ACK, FIN, etc)
+ * @len: packet length
  *
  * In the "application push" invocation, the TCP header with all
  * its information is pointed to by the packet pointer.
  */
-static void wget_handler(uchar *pkt, unsigned int tcp_seq_num,
-			 struct in_addr action_and_state,
-			 unsigned int tcp_ack_num, unsigned int len)
+static void wget_handler(uchar *pkt, u16 dport,
+			 struct in_addr sip, u16 sport,
+			 u32 tcp_seq_num, u32 tcp_ack_num,
+			 u8 action, unsigned int len)
 {
 	enum tcp_state wget_tcp_state = tcp_get_tcp_state();
-	u8 action = action_and_state.s_addr;
 
 	net_set_timeout_handler(wget_timeout, wget_timeout_handler);
 	packets++;
@@ -294,7 +295,7 @@
 		break;
 	case WGET_CONNECTING:
 		debug_cond(DEBUG_WGET,
-			   "wget: Connecting In len=%x, Seq=%x, Ack=%x\n",
+			   "wget: Connecting In len=%x, Seq=%u, Ack=%u\n",
 			   len, tcp_seq_num, tcp_ack_num);
 		if (!len) {
 			if (wget_tcp_state == TCP_ESTABLISHED) {
@@ -310,14 +311,13 @@
 		}
 		break;
 	case WGET_CONNECTED:
-		debug_cond(DEBUG_WGET, "wget: Connected seq=%x, len=%x\n",
+		debug_cond(DEBUG_WGET, "wget: Connected seq=%u, len=%x\n",
 			   tcp_seq_num, len);
 		if (!len) {
 			wget_fail("Image not found, no data returned\n",
 				  tcp_seq_num, tcp_ack_num, action);
 		} else {
-			wget_connected(pkt, tcp_seq_num, action_and_state,
-				       tcp_ack_num, len);
+			wget_connected(pkt, tcp_seq_num, action, tcp_ack_num, len);
 		}
 		break;
 	case WGET_TRANSFERRING:
@@ -338,6 +338,7 @@
 			wget_send(TCP_ACK, tcp_seq_num, tcp_ack_num, len);
 			fallthrough;
 		case TCP_SYN_SENT:
+		case TCP_SYN_RECEIVED:
 		case TCP_CLOSING:
 		case TCP_FIN_WAIT_1:
 		case TCP_CLOSED: