diff --git a/include/net.h b/include/net.h
index 675bf4171b..220eba2e21 100644
--- a/include/net.h
+++ b/include/net.h
@@ -365,6 +365,7 @@ struct vlan_ethernet_hdr {
 #define PROT_NCSI	0x88f8		/* NC-SI control packets        */
 
 #define IPPROTO_ICMP	 1	/* Internet Control Message Protocol	*/
+#define IPPROTO_TCP	 6	/* Transmission Control Protocol	*/
 #define IPPROTO_UDP	17	/* User Datagram Protocol		*/
 
 /*
@@ -687,7 +688,7 @@ static inline void net_send_packet(uchar *pkt, int len)
 }
 
 /*
- * Transmit "net_tx_packet" as UDP packet, performing ARP request if needed
+ * Transmit "net_tx_packet" as UDP or TCP packet, send ARP request if needed
  *  (ether will be populated)
  *
  * @param ether Raw packet buffer
@@ -695,10 +696,15 @@ static inline void net_send_packet(uchar *pkt, int len)
  * @param dport Destination UDP port
  * @param sport Source UDP port
  * @param payload_len Length of data after the UDP header
+ * @param action TCP action to be performed
+ * @param tcp_seq_num TCP sequence number of this transmission
+ * @param tcp_ack_num TCP stream acknolegement number
  */
 int net_send_ip_packet(uchar *ether, struct in_addr dest, int dport, int sport,
 		       int payload_len, int proto, u8 action, u32 tcp_seq_num,
 		       u32 tcp_ack_num);
+int net_send_tcp_packet(int payload_len, int dport, int sport, u8 action,
+			u32 tcp_seq_num, u32 tcp_ack_num);
 int net_send_udp_packet(uchar *ether, struct in_addr dest, int dport,
 			int sport, int payload_len);
 
diff --git a/include/net/tcp.h b/include/net/tcp.h
new file mode 100644
index 0000000000..417a6d0f4e
--- /dev/null
+++ b/include/net/tcp.h
@@ -0,0 +1,222 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * TCP Support with SACK for file transfer.
+ *
+ * Copyright 2017 Duncan Hare, All rights reserved.
+ */
+
+#define TCP_ACTIVITY 127		/* Number of packets received   */
+					/* before console progress mark */
+
+struct ip_tcp_hdr {
+	u8		ip_hl_v;	/* header length and version	*/
+	u8		ip_tos;		/* type of service		*/
+	u16		ip_len;		/* total length			*/
+	u16		ip_id;		/* identification		*/
+	u16		ip_off;		/* fragment offset field	*/
+	u8		ip_ttl;		/* time to live			*/
+	u8		ip_p;		/* protocol			*/
+	u16		ip_sum;		/* checksum			*/
+	struct in_addr	ip_src;		/* Source IP address		*/
+	struct in_addr	ip_dst;		/* Destination IP address	*/
+	u16		tcp_src;	/* TCP source port		*/
+	u16		tcp_dst;	/* TCP destination port		*/
+	u32		tcp_seq;	/* TCP sequence number		*/
+	u32		tcp_ack;	/* TCP Acknowledgment number	*/
+	u8		tcp_hlen;	/* 4 bits TCP header Length/4	*/
+					/* 4 bits Reserved		*/
+					/* 2 more bits reserved		*/
+	u8		tcp_flags;	/* see defines			*/
+	u16		tcp_win;	/* TCP windows size		*/
+	u16		tcp_xsum;	/* Checksum			*/
+	u16		tcp_ugr;	/* Pointer to urgent data	*/
+} __packed;
+
+#define IP_TCP_HDR_SIZE		(sizeof(struct ip_tcp_hdr))
+#define TCP_HDR_SIZE		(IP_TCP_HDR_SIZE  - IP_HDR_SIZE)
+
+#define TCP_DATA	0x00	/* Data Packet - internal use only	*/
+#define TCP_FIN		0x01	/* Finish flag				*/
+#define TCP_SYN		0x02	/* Synch (start) flag			*/
+#define TCP_RST		0x04	/* reset flag				*/
+#define TCP_PUSH	0x08	/* Push - Notify app			*/
+#define TCP_ACK		0x10	/* Acknowledgment of data received	*/
+#define TCP_URG		0x20	/* Urgent				*/
+#define TCP_ECE		0x40	/* Congestion control			*/
+#define TCP_CWR		0x80	/* Congestion Control			*/
+
+/*
+ * TCP header options, Seq, MSS, and SACK
+ */
+
+#define TCP_SACK 32			/* Number of packets analyzed   */
+					/* on leading edge of stream    */
+
+#define TCP_O_END	0x00		/* End of option list		*/
+#define TCP_1_NOP	0x01		/* Single padding NOP		*/
+#define TCP_O_NOP	0x01010101	/* NOPs pad to 32 bit boundary	*/
+#define TCP_O_MSS	0x02		/* MSS Size option		*/
+#define TCP_O_SCL	0x03		/* Window Scale option		*/
+#define TCP_P_SACK	0x04		/* SACK permitted		*/
+#define TCP_V_SACK	0x05		/* SACK values			*/
+#define TCP_O_TS	0x08		/* Timestamp option		*/
+#define TCP_OPT_LEN_2	0x02
+#define TCP_OPT_LEN_3	0x03
+#define TCP_OPT_LEN_4	0x04
+#define TCP_OPT_LEN_6	0x06
+#define TCP_OPT_LEN_8	0x08
+#define TCP_OPT_LEN_A	0x0a		/* Timestamp Length		*/
+
+/*
+ * Please review the warning in net.c about these two parameters.
+ * They are part of a promise of RX buffer size to the sending TCP
+ */
+
+#define TCP_MSS		1460		/* Max segment size		*/
+#define TCP_SCALE	0x01		/* Scale			*/
+
+struct tcp_mss {			/* TCP Max Segment size		*/
+	u8	kind;			/* Field ID			*/
+	u8	len;			/* Field length			*/
+	u16	mss;			/* Segment size value		*/
+} __packed;
+
+struct tcp_scale {			/* TCP Windows Scale		*/
+	u8	kind;			/* Field ID			*/
+	u8	len;			/* Filed length			*/
+	u8	scale;			/* windows shift value used for */
+					/* networks with many hops	*/
+					/* Typically 4 or more hops	*/
+} __packed;
+
+struct tcp_sack_p {			/* SACK permitted		*/
+	u8	kind;			/* Field Id			*/
+	u8	len;			/* Field length			*/
+} __packed;
+
+struct sack_edges {
+	u32	l;			/* Left edge of stream		*/
+	u32	r;			/* right edge of stream		*/
+} __packed;
+
+#define TCP_SACK_SIZE (sizeof(struct sack_edges))
+
+/*
+ * A TCP stream has holes when packets are missing or disordered.
+ * A hill is the inverse of a hole, and is data received.
+ * TCP received hills (a sequence of data), and inferrs Holes
+ * from the "hills" or packets received.
+ */
+
+#define TCP_SACK_HILLS	4
+
+struct tcp_sack_v {
+	u8	kind;			/* Field ID		        */
+	u8	len;			/* Field Length			*/
+	struct	sack_edges hill[TCP_SACK_HILLS]; /* L & R window edges	*/
+} __packed;
+
+struct tcp_t_opt {			/* TCP time stamps option	*/
+	u8	kind;			/* Field id			*/
+	u8	len;			/* Field length			*/
+	u32	t_snd;			/* Sender timestamp		*/
+	u32	t_rcv;			/* Receiver timestamp		*/
+} __packed;
+
+#define TCP_TSOPT_SIZE (sizeof(struct tcp_t_opt))
+
+/*
+ * ip tcp  structure with options
+ */
+
+struct ip_tcp_hdr_o {
+	struct	ip_tcp_hdr hdr;
+	struct	tcp_mss	   mss;
+	struct	tcp_scale  scale;
+	struct	tcp_sack_p sack_p;
+	struct	tcp_t_opt  t_opt;
+	u8	end;
+} __packed;
+
+#define IP_TCP_O_SIZE (sizeof(struct ip_tcp_hdr_o))
+
+struct ip_tcp_hdr_s {
+	struct	ip_tcp_hdr	hdr;
+	struct	tcp_t_opt	t_opt;
+	struct	tcp_sack_v	sack_v;
+	u8	end;
+} __packed;
+
+#define IP_TCP_SACK_SIZE (sizeof(struct ip_tcp_hdr_s))
+
+/*
+ * TCP pseudo header definitions
+ */
+#define PSEUDO_PAD_SIZE	8
+
+struct pseudo_hdr {
+	u8 padding[PSEUDO_PAD_SIZE];	/* pseudo hdr size = ip_tcp hdr size */
+	struct in_addr p_src;
+	struct in_addr p_dst;
+	u8      rsvd;
+	u8      p;
+	u16     len;
+} __packed;
+
+#define PSEUDO_HDR_SIZE	(sizeof(struct pseudo_hdr)) - PSEUDO_PAD_SIZE
+
+/*
+ * union for building TCP/IP packet. Build Pseudo header in packed buffer
+ * first, calculate TCP checksum, then build IP header in packed buffer.
+ */
+
+union tcp_build_pkt {
+	struct pseudo_hdr ph;
+	struct ip_tcp_hdr_o ip;
+	struct ip_tcp_hdr_s sack;
+	uchar  raw[1600];
+} __packed;
+
+/*
+ * TCP State machine states for connection
+ */
+
+enum TCP_STATE {
+	TCP_CLOSED,		/* Need to send SYN to connect		  */
+	TCP_SYN_SENT,		/* Trying to connect, waiting for SYN 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 */
+	TCP_FIN_WAIT_1,		/* Sent FIN waiting for response	  */
+	TCP_FIN_WAIT_2		/* Rec ACK from FIN sent, waiting for FIN */
+};
+
+enum TCP_STATE tcp_get_tcp_state(void);
+void tcp_set_tcp_state(enum TCP_STATE new_state);
+int tcp_set_tcp_header(uchar *pkt, int dport, int sport, int payload_len,
+		       u8 action, u32 tcp_seq_num, u32 tcp_ack_num);
+
+/*
+ * An incoming packet handler.
+ * @param pkt    pointer to the application packet
+ * @param dport  destination UDP port
+ * @param sip    source IP address
+ * @param sport  source UDP port
+ * @param len    packet length
+ */
+typedef void rxhand_tcp(uchar *pkt, unsigned int dport,
+			struct in_addr sip, unsigned int sport,
+			unsigned int len);
+void tcp_set_tcp_handler(rxhand_tcp *f);
+
+void rxhand_tcp_f(union tcp_build_pkt *b, unsigned int len);
+
+/*
+ * An incoming TCP packet handler for the TCP protocol.
+ * There is also a dynamic function pointer for TCP based commands to
+ * receive incoming traffic after the TCP protocol code has done its work.
+ */
+
+void rxhand_action(u8 tcp_action, int payload_len, u32 tcp_seq_num,
+		   u32 tcp_ack_num, unsigned int pkt_len,
+		   union tcp_build_pkt *b);
diff --git a/net/Kconfig b/net/Kconfig
index ef0aa161f7..73e4bcb88e 100644
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -159,6 +159,18 @@ config BOOTP_SERVERIP
 	  variable, not the BOOTP server. This affects the operation of both
 	  bootp and tftp.
 
+config PROT_TCP
+	bool "TCP stack"
+	help
+	  Enable a generic tcp framework that allows defining a custom
+	  handler for tcp protocol.
+
+config PROT_TCP_SACK
+	bool "TCP SACK support"
+	help
+	  TCP protocol with SACK. Selecting this will provide the fastest
+	  file transfer possible.
+
 endif   # if NET
 
 config SYS_RX_ETH_BUFFER
diff --git a/net/Makefile b/net/Makefile
index fb3eba840f..f68ad94767 100644
--- a/net/Makefile
+++ b/net/Makefile
@@ -29,6 +29,7 @@ obj-$(CONFIG_CMD_TFTPBOOT) += tftp.o
 obj-$(CONFIG_UDP_FUNCTION_FASTBOOT)  += fastboot.o
 obj-$(CONFIG_CMD_WOL)  += wol.o
 obj-$(CONFIG_PROT_UDP) += udp.o
+obj-$(CONFIG_PROT_TCP) += tcp.o
 
 # Disable this warning as it is triggered by:
 # sprintf(buf, index ? "foo%d" : "foo", index)
diff --git a/net/net.c b/net/net.c
index 072a82d8f9..28d9fbd227 100644
--- a/net/net.c
+++ b/net/net.c
@@ -116,6 +116,7 @@
 #if defined(CONFIG_CMD_WOL)
 #include "wol.h"
 #endif
+#include <net/tcp.h>
 
 /** BOOTP EXTENTIONS **/
 
@@ -386,6 +387,8 @@ int net_init(void)
 
 		/* Only need to setup buffer pointers once. */
 		first_call = 0;
+		if (IS_ENABLED(CONFIG_PROT_TCP))
+			tcp_set_tcp_state(TCP_CLOSED);
 	}
 
 	return net_init_loop();
@@ -816,6 +819,16 @@ int net_send_udp_packet(uchar *ether, struct in_addr dest, int dport, int sport,
 				  IPPROTO_UDP, 0, 0, 0);
 }
 
+#if defined(CONFIG_PROT_TCP)
+int net_send_tcp_packet(int payload_len, int dport, int sport, u8 action,
+			u32 tcp_seq_num, u32 tcp_ack_num)
+{
+	return net_send_ip_packet(net_server_ethaddr, net_server_ip, dport,
+				  sport, payload_len, IPPROTO_TCP, action,
+				  tcp_seq_num, tcp_ack_num);
+}
+#endif
+
 int net_send_ip_packet(uchar *ether, struct in_addr dest, int dport, int sport,
 		       int payload_len, int proto, u8 action, u32 tcp_seq_num,
 		       u32 tcp_ack_num)
@@ -847,6 +860,14 @@ int net_send_ip_packet(uchar *ether, struct in_addr dest, int dport, int sport,
 				   payload_len);
 		pkt_hdr_size = eth_hdr_size + IP_UDP_HDR_SIZE;
 		break;
+#if defined(CONFIG_PROT_TCP)
+	case IPPROTO_TCP:
+		pkt_hdr_size = eth_hdr_size +
+		tcp_set_tcp_header(pkt + eth_hdr_size, dport, sport,
+				   payload_len, action, tcp_seq_num,
+				   tcp_ack_num);
+	break;
+#endif
 	default:
 		return -EINVAL;
 	}
@@ -1253,6 +1274,15 @@ void net_process_received_packet(uchar *in_packet, int len)
 		if (ip->ip_p == IPPROTO_ICMP) {
 			receive_icmp(ip, len, src_ip, et);
 			return;
+#if defined(CONFIG_PROT_TCP)
+		} else if (ip->ip_p == IPPROTO_TCP) {
+			debug_cond(DEBUG_DEV_PKT,
+				   "TCP PH (to=%pI4, from=%pI4, len=%d)\n",
+				   &dst_ip, &src_ip, len);
+
+			rxhand_tcp_f((union tcp_build_pkt *)ip, len);
+			return;
+#endif
 		} else if (ip->ip_p != IPPROTO_UDP) {	/* Only UDP packets */
 			return;
 		}
diff --git a/net/tcp.c b/net/tcp.c
new file mode 100644
index 0000000000..ebd349c3e8
--- /dev/null
+++ b/net/tcp.c
@@ -0,0 +1,709 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2017 Duncan Hare, all rights reserved.
+ */
+
+/*
+ * General Desription:
+ *
+ * TCP support for the wget command, for fast file downloading.
+ *
+ * HTTP/TCP Receiver:
+ *
+ *      Prerequisites:  - own ethernet address
+ *                      - own IP address
+ *                      - Server IP address
+ *                      - Server with TCP
+ *                      - TCP application (eg wget)
+ *      Next Step       HTTPS?
+ */
+#include <common.h>
+#include <command.h>
+#include <console.h>
+#include <env_internal.h>
+#include <errno.h>
+#include <net.h>
+#include <net/tcp.h>
+
+/*
+ * TCP sliding window  control used by us to request re-TX
+ */
+
+static struct tcp_sack_v tcp_lost;
+
+/* TCP option timestamp */
+static u32 loc_timestamp;
+static u32 rmt_timestamp;
+
+u32 tcp_seq_init;
+u32 tcp_ack_edge;
+u32 tcp_seq_max;
+
+int tcp_activity_count;
+
+/*
+ * Search for TCP_SACK and review the comments before the code section
+ * TCP_SACK is the number of packets at the front of the stream
+ */
+
+enum pkt_state {PKT, NOPKT};
+struct sack_r {
+	struct sack_edges se;
+	enum   pkt_state st;
+};
+
+struct sack_r edge_a[TCP_SACK];
+unsigned int sack_idx;
+unsigned int prev_len;
+
+/* TCP connection state */
+static enum TCP_STATE tcp_state;
+
+/*
+ * An incoming TCP packet handler for the TCP protocol.
+ * There is also a dynamic function pointer for TCP based commands to
+ * receive incoming traffic after the TCP protocol code has done its work.
+ */
+
+/* Current TCP RX packet handler */
+static rxhand_tcp *tcp_packet_handler;
+
+enum TCP_STATE tcp_get_tcp_state(void)
+{
+	return tcp_state;
+}
+
+void tcp_set_tcp_state(enum TCP_STATE new_state)
+{
+	tcp_state = new_state;
+}
+
+static void dummy_handler(uchar *pkt, unsigned int dport,
+			  struct in_addr sip, unsigned int sport,
+			  unsigned int len)
+{
+}
+
+void tcp_set_tcp_handler(rxhand_tcp *f)
+{
+	debug_cond(DEBUG_INT_STATE, "--- net_loop TCP handler set (%p)\n", f);
+	if (!f)
+		tcp_packet_handler = dummy_handler;
+	else
+		tcp_packet_handler = f;
+}
+
+u16 tcp_set_pseudo_header(uchar *pkt, struct in_addr src, struct in_addr dest,
+			  int tcp_len, int pkt_len)
+{
+	union tcp_build_pkt *b = (union tcp_build_pkt *)pkt;
+	int checksum_len;
+
+	/*
+	 * Pseudo header
+	 *
+	 * Zero the byte after the last byte so that the header checksum
+	 * will always work.
+	 */
+
+	pkt[pkt_len] = 0x00;
+
+	net_copy_ip((void *)&b->ph.p_src, &src);
+	net_copy_ip((void *)&b->ph.p_dst, &dest);
+	b->ph.rsvd	= 0x00;
+	b->ph.p		= IPPROTO_TCP;
+	b->ph.len	= htons(tcp_len);
+	checksum_len	= tcp_len + PSEUDO_HDR_SIZE;
+
+	debug_cond(DEBUG_DEV_PKT,
+		   "TCP Pesudo  Header  (to=%pI4, from=%pI4, Len=%d)\n",
+		   &b->ph.p_dst, &b->ph.p_src, checksum_len);
+
+	return compute_ip_checksum(pkt + PSEUDO_PAD_SIZE, checksum_len);
+}
+
+int net_set_ack_options(union tcp_build_pkt *b)
+{
+	b->sack.hdr.tcp_hlen  = (TCP_HDR_SIZE >> 2) << 4;
+
+	b->sack.t_opt.kind  = TCP_O_TS;
+	b->sack.t_opt.len   = TCP_OPT_LEN_A;
+	b->sack.t_opt.t_snd = htons(loc_timestamp);
+	b->sack.t_opt.t_rcv = rmt_timestamp;
+	b->sack.sack_v.kind = TCP_1_NOP;
+	b->sack.sack_v.len  = 0x00;
+
+#if defined(CONFIG_PROT_TCP_SACK)
+	if (tcp_lost.len > TCP_OPT_LEN_2) {
+		debug_cond(DEBUG_DEV_PKT, "TCP ack opt lost.len %x\n",
+			   tcp_lost.len);
+		b->sack.sack_v.len       = tcp_lost.len;
+		b->sack.sack_v.kind      = TCP_V_SACK;
+		b->sack.sack_v.hill[0].l = htonl(tcp_lost.hill[0].l);
+		b->sack.sack_v.hill[0].r = htonl(tcp_lost.hill[0].r);
+
+		/*
+		 * These SACK structures are initialized with NOPs to
+		 * provide TCP header alignment padding. There are 4
+		 * SACK structures used for both header padding and
+		 * internally.
+		 */
+
+		b->sack.sack_v.hill[1].l = htonl(tcp_lost.hill[1].l);
+		b->sack.sack_v.hill[1].r = htonl(tcp_lost.hill[1].r);
+		b->sack.sack_v.hill[2].l = htonl(tcp_lost.hill[2].l);
+		b->sack.sack_v.hill[2].r = htonl(tcp_lost.hill[2].r);
+		b->sack.sack_v.hill[3].l = TCP_O_NOP;
+		b->sack.sack_v.hill[3].r = TCP_O_NOP;
+	}
+
+	/*
+	 * TCP lengths are stored as a rounded up number of 32 bit words
+	 * Add 3 to length round up, rounded, then divided into the length
+	 * in 32 bit words.
+	 */
+
+	b->sack.hdr.tcp_hlen = (((TCP_HDR_SIZE + TCP_TSOPT_SIZE
+				+ tcp_lost.len + 3)  >> 2) << 4);
+
+#else
+	b->sack.sack_v.kind = 0x00;
+	b->sack.hdr.tcp_hlen = (((TCP_HDR_SIZE + TCP_TSOPT_SIZE
+				+ 3)  >> 2) << 4);
+#endif
+	/*
+	 * This returns the actual rounded up length of the
+	 * TCP header to add to the total packet length
+	 */
+
+	return b->sack.hdr.tcp_hlen >> 2;
+}
+
+void net_set_syn_options(union tcp_build_pkt *b)
+{
+	tcp_lost.len		= 0;
+	b->ip.hdr.tcp_hlen      = 0xa0;
+
+	b->ip.mss.kind          = TCP_O_MSS;
+	b->ip.mss.len           = TCP_OPT_LEN_4;
+	b->ip.mss.mss           = htons(TCP_MSS);
+	b->ip.scale.kind        = TCP_O_SCL;
+	b->ip.scale.scale       = TCP_SCALE;
+	b->ip.scale.len         = TCP_OPT_LEN_3;
+#if defined(CONFIG_PROT_TCP_SACK)
+	b->ip.sack_p.kind       = TCP_P_SACK;
+	b->ip.sack_p.len        = TCP_OPT_LEN_2;
+#else
+	b->ip.sack_p.kind       = TCP_1_NOP;
+	b->ip.sack_p.len        = TCP_1_NOP;
+#endif
+	b->ip.t_opt.kind        = TCP_O_TS;
+	b->ip.t_opt.len         = TCP_OPT_LEN_A;
+	loc_timestamp           = get_ticks();
+	rmt_timestamp           = 0x00000000;
+	b->ip.t_opt.t_snd       = 0;
+	b->ip.t_opt.t_rcv       = 0x00000000;
+	b->ip.end               = TCP_O_END;
+}
+
+int tcp_set_tcp_header(uchar *pkt, int dport, int sport, int payload_len,
+		       u8 action, u32 tcp_seq_num, u32 tcp_ack_num)
+{
+	union tcp_build_pkt *b = (union tcp_build_pkt *)pkt;
+	int	pkt_hdr_len;
+	int	pkt_len;
+	int	tcp_len;
+
+/*
+ * Header: 5 32 bit words. 4 bits TCP header Length, 4 bits reserved options
+ */
+	b->ip.hdr.tcp_flags	= action;
+	pkt_hdr_len		= IP_TCP_HDR_SIZE;
+	b->ip.hdr.tcp_hlen      = 0x50;
+
+	switch (action) {
+	case TCP_SYN:
+		debug_cond(DEBUG_DEV_PKT,
+			   "TCP Hdr:SYN (%pI4, %pI4, sq=%d, ak=%d)\n",
+			   &net_server_ip, &net_ip,
+			   tcp_seq_num, tcp_ack_num);
+		tcp_activity_count = 0;
+		net_set_syn_options(b);
+		tcp_seq_num = 0;
+		tcp_ack_num = 0;
+		pkt_hdr_len = IP_TCP_O_SIZE;
+		if (tcp_state == TCP_SYN_SENT) {  /* Too many SYNs */
+			action    = TCP_FIN;
+			tcp_state = TCP_FIN_WAIT_1;
+		} else {
+			tcp_state = TCP_SYN_SENT;
+		}
+	break;
+	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",
+			   &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",
+			   &net_server_ip, &net_ip, tcp_seq_num, tcp_ack_num);
+		payload_len = 0;
+		pkt_hdr_len = IP_TCP_HDR_SIZE;
+		tcp_state   = TCP_FIN_WAIT_1;
+
+	break;
+
+	/* Notify connection closing */
+
+	case (TCP_FIN | TCP_ACK):
+	case ((TCP_FIN | TCP_ACK) | TCP_PUSH):
+		if (tcp_state == TCP_CLOSE_WAIT)
+			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",
+			   &net_server_ip, &net_ip,
+			   tcp_seq_num, tcp_ack_edge, action);
+					/* FALLTHRU */
+	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",
+			   &net_server_ip, &net_ip,
+			   tcp_seq_num, tcp_ack_num, action);
+	}
+
+	pkt_len	= pkt_hdr_len + payload_len;
+	tcp_len	= pkt_len - IP_HDR_SIZE;
+
+	/* 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.
+	 * Change tcp_win only if you have an understanding of network
+	 * overrun, congestion, TCP segment sizes, TCP windows, TCP scale,
+	 * queuing theory  and packet buffering. If there are too few buffers,
+	 * there will be data loss, recovery may work or the sending TCP,
+	 * the server, could abort the stream transmission.
+	 * MSS is governed by maximum Ethernet frame length.
+	 * The number of buffers is governed by the desire to have a queue of
+	 * full buffers to be processed at the destination to maximize
+	 * throughput. Temporary memory use for the boot phase on modern
+	 * SOCs is may not be considered a constraint to buffer space, if
+	 * it is, then the u-boot tftp or nfs kernel netboot should be
+	 * considered.
+	 */
+
+	b->ip.hdr.tcp_win	= htons(PKTBUFSRX * TCP_MSS >>  TCP_SCALE);
+
+	b->ip.hdr.tcp_xsum	= 0x0000;
+	b->ip.hdr.tcp_ugr	= 0x0000;
+
+	b->ip.hdr.tcp_xsum = tcp_set_pseudo_header(pkt, net_ip, net_server_ip,
+						   tcp_len, pkt_len);
+
+	net_set_ip_header((uchar *)&b->ip, net_server_ip, net_ip,
+			  pkt_len, IPPROTO_TCP);
+
+	return pkt_hdr_len;
+}
+
+/*
+ * Selective Acknowledgment (Essential for fast stream transfer)
+ */
+
+void tcp_hole(u32 tcp_seq_num, u32 len, u32 tcp_seq_max)
+{
+	unsigned int idx_sack;
+	unsigned int sack_end = TCP_SACK - 1;
+	unsigned int sack_in;
+	unsigned int hill = 0;
+	enum pkt_state expect = PKT;
+
+	u32 seq   = tcp_seq_num - tcp_seq_init;
+	u32 hol_l = tcp_ack_edge - tcp_seq_init;
+	u32 hol_r = 0;
+
+	/* Place new seq number in correct place in receive array */
+
+	if (prev_len == 0)
+		prev_len = len;
+	idx_sack = sack_idx + ((tcp_seq_num - tcp_ack_edge) / prev_len);
+	if (idx_sack < TCP_SACK) {
+		edge_a[idx_sack].se.l = tcp_seq_num;
+		edge_a[idx_sack].se.r = tcp_seq_num + len;
+		edge_a[idx_sack].st   = PKT;
+
+/*
+ * The fin (last) packet is not the same length as data packets, and if it's
+ * length is recorded and used for array index calculation, calculation breaks.
+ */
+		if (prev_len < len)
+			prev_len = len;
+	}
+
+	debug_cond(DEBUG_DEV_PKT,
+		   "TCP 1 seq %d, edg %d, len %d, sack_idx %d, sack_end %d\n",
+		    seq, hol_l, len, sack_idx, sack_end);
+
+	/* Right edge of contiguous stream, is the left edge of first hill */
+
+	hol_l = tcp_seq_num - tcp_seq_init;
+	hol_r = hol_l + len;
+
+	tcp_lost.len = TCP_OPT_LEN_2;
+
+	debug_cond(DEBUG_DEV_PKT,
+		   "TCP 1 in %d, seq %d, pkt_l %d, pkt_r %d, sack_idx %d, sack_end %d\n",
+		   idx_sack, seq, hol_l, hol_r, sack_idx, sack_end);
+
+	for (sack_in = sack_idx; sack_in < sack_end && hill < TCP_SACK_HILLS;
+		 sack_in++)  {
+		switch (expect) {
+		case NOPKT:
+			switch (edge_a[sack_in].st) {
+			case NOPKT:
+				debug_cond(DEBUG_INT_STATE, "N");
+			break;
+			case PKT:
+				debug_cond(DEBUG_INT_STATE, "n");
+					tcp_lost.hill[hill].l =
+						edge_a[sack_in].se.l;
+					tcp_lost.hill[hill].r =
+						edge_a[sack_in].se.r;
+				expect = PKT;
+			break;
+			}
+		break;
+		case PKT:
+			switch (edge_a[sack_in].st) {
+			case NOPKT:
+				debug_cond(DEBUG_INT_STATE, "p");
+				if (sack_in > sack_idx &&
+				    hill < TCP_SACK_HILLS) {
+					hill++;
+					tcp_lost.len += TCP_OPT_LEN_8;
+				}
+				expect = NOPKT;
+			break;
+			case PKT:
+				debug_cond(DEBUG_INT_STATE, "P");
+
+				if (tcp_ack_edge == edge_a[sack_in].se.l) {
+					tcp_ack_edge = edge_a[sack_in].se.r;
+					edge_a[sack_in].st = NOPKT;
+					sack_idx++;
+				} else {
+					if (hill < TCP_SACK_HILLS)
+						tcp_lost.hill[hill].r =
+							edge_a[sack_in].se.r;
+				if (sack_in == sack_end - 1)
+					tcp_lost.hill[hill].r =
+						edge_a[sack_in].se.r;
+				}
+			break;
+			}
+		break;
+		}
+	}
+	debug_cond(DEBUG_INT_STATE, "\n");
+	if (tcp_lost.len <= TCP_OPT_LEN_2)
+		sack_idx = 0;
+}
+
+void tcp_parse_options(uchar *o, int o_len)
+{
+	struct tcp_t_opt  *tsopt;
+	uchar *p = o;
+/*
+ *	NOPs are options with a zero length, and thus are special.
+ *	All other options have length fields.
+ */
+
+	for (p = o; p < (o + o_len); p = p + p[1]) {
+		if (p[1] != 0) {
+			switch (p[0]) {
+			case TCP_O_END:
+				return; /* Finished processing options */
+			case TCP_O_MSS:
+			case TCP_O_SCL:
+			case TCP_P_SACK:
+			case TCP_V_SACK:
+				break; /* Continue to process options */
+			case TCP_O_TS:
+				tsopt = (struct tcp_t_opt *)p;
+				rmt_timestamp = tsopt->t_snd;
+				return;
+			break;
+			} /* End switch, process optional NOPs */
+
+			if (p[0] == TCP_O_NOP)
+				p++;
+		} else {
+			return; /* Finished processing options */
+		}
+	}
+}
+
+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;
+	u8  tcp_rst  = tcp_flags & TCP_RST;
+	u8  tcp_push = tcp_flags & TCP_PUSH;
+	u8  tcp_ack  = tcp_flags & TCP_ACK;
+	u8  action   = TCP_DATA;
+	int i;
+
+	/*
+	 * tcp_flags are examined to determine TX action in a given state
+	 * tcp_push is interpreted to mean "inform the app"
+	 * urg, ece, cer and nonce flags are not supported.
+	 *
+	 * exe and crw are use to signal and confirm knowledge of congestion.
+	 * This TCP only sends a file request and acks. If it generates
+	 * congestion, the network is broken.
+	 */
+
+	debug_cond(DEBUG_INT_STATE, "TCP STATE ENTRY %x\n", action);
+	if (tcp_rst) {
+		action    = TCP_DATA;
+		tcp_state = TCP_CLOSED;
+		net_set_state(NETLOOP_FAIL);
+		debug_cond(DEBUG_INT_STATE, "TCP Reset %x\n", tcp_flags);
+		return TCP_RST;
+	}
+
+	switch  (tcp_state) {
+	case TCP_CLOSED:
+		debug_cond(DEBUG_INT_STATE, "TCP CLOSED %x\n", tcp_flags);
+		if (tcp_fin)
+			action = TCP_DATA;
+		if (tcp_syn)
+			action = TCP_RST;
+		if (tcp_ack)
+			action = TCP_DATA;
+		break;
+	case TCP_SYN_SENT:
+		debug_cond(DEBUG_INT_STATE, "TCP_SYN_SENT %x, %d\n",
+			   tcp_flags, *tcp_seq_num);
+		if (tcp_fin) {
+			action = action | TCP_PUSH;
+			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;
+				tcp_state             = TCP_ESTABLISHED;
+				for (i = 0; i < TCP_SACK; i++)
+					edge_a[i].st   = NOPKT;
+			}
+		} else {
+			if (tcp_ack)
+				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_fin = TCP_DATA;  /* cause standalone FIN */
+		}
+
+		if ((tcp_fin) && tcp_lost.len <= TCP_OPT_LEN_2) {
+			action    = action | TCP_FIN | TCP_PUSH | TCP_ACK;
+			tcp_state =  TCP_CLOSE_WAIT;
+		} else {
+			if (tcp_ack)
+				action = TCP_DATA;
+		}
+		if (tcp_push)
+			action = action | TCP_PUSH;
+		if (tcp_syn)
+			action = TCP_ACK + TCP_RST;
+		break;
+	case TCP_CLOSE_WAIT:
+		debug_cond(DEBUG_INT_STATE, "TCP_CLOSE_WAIT (%x)\n", tcp_flags);
+		action = TCP_DATA;			/* Wait for app	*/
+		break;
+	case TCP_FIN_WAIT_2:
+		debug_cond(DEBUG_INT_STATE, "TCP_FIN_WAIT_2 (%x)\n", tcp_flags);
+		if (tcp_fin)
+			action =  TCP_DATA;
+		if (tcp_syn)
+			action =  TCP_DATA;
+		if (tcp_ack) {
+			action =  TCP_PUSH | TCP_ACK;
+			tcp_state = TCP_CLOSED;
+			puts("\n");
+		}
+		break;
+	case TCP_FIN_WAIT_1:
+		debug_cond(DEBUG_INT_STATE, "TCP_FIN_WAIT_1 (%x)\n", tcp_flags);
+		if (tcp_fin) {
+			action = TCP_ACK | TCP_FIN;
+			 tcp_state = TCP_FIN_WAIT_2;
+		}
+		if (tcp_syn)
+			action =  TCP_RST;
+		if (tcp_ack) {
+			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);
+		if (tcp_fin)
+			action = TCP_DATA;
+		if (tcp_syn)
+			action = TCP_RST;
+		if (tcp_ack) {
+			action = TCP_PUSH;
+			tcp_state = TCP_CLOSED;
+			puts("\n");
+		}
+		break;
+	}
+	return action;
+}
+
+void rxhand_tcp_f(union tcp_build_pkt *b, unsigned int pkt_len)
+{
+	int tcp_len = pkt_len - IP_HDR_SIZE;
+	u16 tcp_rx_xsum = b->ip.hdr.ip_sum;
+	u8  tcp_action = TCP_DATA;
+	u32 tcp_seq_num;
+	u32 tcp_ack_num;
+	struct in_addr action_and_state;
+
+	int tcp_hdr_len;
+	int payload_len;
+
+	/*
+	 * Verify IP header
+	 */
+	debug_cond(DEBUG_DEV_PKT,
+		   "TCP RX in RX Sum (to=%pI4, from=%pI4, len=%d)\n",
+			   &b->ip.hdr.ip_src, &b->ip.hdr.ip_dst, pkt_len);
+
+	debug_cond(DEBUG_DEV_PKT,
+		   "In__________________________________________\n");
+
+	b->ip.hdr.ip_src = net_server_ip;
+	b->ip.hdr.ip_dst = net_ip;
+	b->ip.hdr.ip_sum = 0x0000;
+	if (tcp_rx_xsum != compute_ip_checksum(b, IP_HDR_SIZE)) {
+		debug_cond(DEBUG_DEV_PKT,
+			   "TCP RX IP xSum Error (%pI4, =%pI4, len=%d)\n",
+			   &net_ip, &net_server_ip, pkt_len);
+		return;
+	}
+
+	/*
+	 * Build pseudo header and verify TCP header
+	 */
+	tcp_rx_xsum = b->ip.hdr.tcp_xsum;
+	b->ip.hdr.tcp_xsum = 0x0000;
+	if (tcp_rx_xsum != tcp_set_pseudo_header((uchar *)b, b->ip.hdr.ip_src,
+						 b->ip.hdr.ip_dst, tcp_len,
+						 pkt_len)) {
+		debug_cond(DEBUG_DEV_PKT,
+			   "TCP RX TCP xSum Error (%pI4, %pI4, len=%d)\n",
+			   &net_ip, &net_server_ip, tcp_len);
+		return;
+	}
+
+	tcp_hdr_len = (b->ip.hdr.tcp_hlen >> 2);
+	payload_len = tcp_len - tcp_hdr_len;
+
+	if (tcp_hdr_len > TCP_HDR_SIZE)
+		tcp_parse_options((uchar *)b + IP_TCP_HDR_SIZE,
+				  tcp_hdr_len - TCP_HDR_SIZE);
+	/*
+	 * Incoming sequence and ack numbers are server's view of the numbers.
+	 * The app must swap the numbers when responding.
+	 */
+
+	tcp_seq_num = ntohl(b->ip.hdr.tcp_seq);
+	tcp_ack_num = ntohl(b->ip.hdr.tcp_ack);
+
+	/* Packets are not ordered. Send to app as received. */
+
+	tcp_action  = tcp_state_machine(b->ip.hdr.tcp_flags,
+					&tcp_seq_num, payload_len);
+
+	/*
+	 * State-altering command to be sent.
+	 * The packet sequence and ack numbers are in the tcp_seq_num
+	 * and tcp_ack_num variables. The current packet, its position
+	 * in the data stream, is the in the range of those variables.
+	 *
+	 * In the "application push" invocation, the TCP header with all
+	 * its information is pointed to by the packet pointer.
+	 *
+	 * In the typedef
+	 *      void rxhand_tcp(uchar *pkt, unsigned int dport,
+	 *                      struct in_addr sip, unsigned int sport,
+	 *                      unsigned int len);
+	 * *pkt is the pointer to the payload
+	 * dport is used for tcp_seg_num
+	 * action_and_state.s_addr is used for TCP state
+	 * sport is used for tcp_ack_num (which is unused by the app)
+	 * pkt_ length is the payload length.
+	 *
+	 * TCP_PUSH from the state machine with a payload length of 0 is a
+	 * connect or disconnect event
+	 */
+
+	tcp_activity_count++;
+	if (tcp_activity_count > TCP_ACTIVITY) {
+		puts("| ");
+		tcp_activity_count = 0;
+	}
+
+	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_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);
+
+	} 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);
+
+		/*
+		 * Warning: Incoming Ack & Seq sequence numbers are transposed
+		 * here to outgoing Seq & Ack sequence numbers
+		 */
+		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);
+	}
+}
