[PATCH v20 1/4] net: Add TCP protocol
Ramon Fried
rfried.dev at gmail.com
Wed Nov 9 09:24:09 CET 2022
On Tue, Nov 8, 2022 at 8:17 AM Ying-Chun Liu (PaulLiu)
<paul.liu at linaro.org> wrote:
>
> From: "Ying-Chun Liu (PaulLiu)" <paul.liu at linaro.org>
>
> Currently file transfers are done using tftp or NFS both
> over udp. This requires a request to be sent from client
> (u-boot) to the boot server.
>
> The current standard is TCP with selective acknowledgment.
>
> Signed-off-by: Duncan Hare <DH at Synoia.com>
> Signed-off-by: Duncan Hare <DuncanCHare at yahoo.com>
> Signed-off-by: Ying-Chun Liu (PaulLiu) <paul.liu at linaro.org>
> Reviewed-by: Simon Glass <sjg at chromium.org>
> Cc: Christian Gmeiner <christian.gmeiner at gmail.com>
> Cc: Joe Hershberger <joe.hershberger at ni.com>
> Cc: Michal Simek <michal.simek at xilinx.com>
> Cc: Ramon Fried <rfried.dev at gmail.com>
> ---
> v1-v12: Made by Duncan, didn't tracked.
> v13: Fix some issues which is reviewed by Christian
> v14: Add options to enable/disable SACK.
> v15: Fix various syntax errors reviewed by Michal.
> Remove magic numbers. Use kernel-doc format.
> v16: Add more kernel-doc. Fix more double spaces.
> v19: export tcp_set_pseudo_header() for unit test.
> ---
> include/net.h | 36 ++-
> include/net/tcp.h | 299 +++++++++++++++++++
> net/Kconfig | 16 ++
> net/Makefile | 1 +
> net/net.c | 30 ++
> net/tcp.c | 720 ++++++++++++++++++++++++++++++++++++++++++++++
> 6 files changed, 1093 insertions(+), 9 deletions(-)
> create mode 100644 include/net/tcp.h
> create mode 100644 net/tcp.c
>
> diff --git a/include/net.h b/include/net.h
> index 32364ed0ce..f4140523c2 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 */
>
> /*
> @@ -690,19 +691,36 @@ static inline void net_send_packet(uchar *pkt, int len)
> (void) eth_send(pkt, len);
> }
>
> -/*
> - * Transmit "net_tx_packet" as UDP packet, performing ARP request if needed
> - * (ether will be populated)
> - *
> - * @param ether Raw packet buffer
> - * @param dest IP address to send the datagram to
> - * @param dport Destination UDP port
> - * @param sport Source UDP port
> - * @param payload_len Length of data after the UDP header
> +/**
> + * net_send_ip_packet() - Transmit "net_tx_packet" as UDP or TCP packet,
> + * send ARP request if needed (ether will be populated)
> + * @ether: Raw packet buffer
> + * @dest: IP address to send the datagram to
> + * @dport: Destination UDP port
> + * @sport: Source UDP port
> + * @payload_len: Length of data after the UDP header
> + * @action: TCP action to be performed
> + * @tcp_seq_num: TCP sequence number of this transmission
> + * @tcp_ack_num: TCP stream acknolegement number
> + *
> + * Return: 0 on success, other value on failure
> */
> 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);
> +/**
> + * net_send_tcp_packet() - Transmit TCP packet.
> + * @payload_len: length of payload
> + * @dport: Destination TCP port
> + * @sport: Source TCP port
> + * @action: TCP action to be performed
> + * @tcp_seq_num: TCP sequence number of this transmission
> + * @tcp_ack_num: TCP stream acknolegement number
> + *
> + * Return: 0 on success, other value on failure
> + */
> +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..322551694f
> --- /dev/null
> +++ b/include/net/tcp.h
> @@ -0,0 +1,299 @@
> +/* 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 - IP and TCP header
> + * @ip_hl_v: header length and version
> + * @ip_tos: type of service
> + * @ip_len: total length
> + * @ip_id: identification
> + * @ip_off: fragment offset field
> + * @ip_ttl: time to live
> + * @ip_p: protocol
> + * @ip_sum: checksum
> + * @ip_src: Source IP address
> + * @ip_dst: Destination IP address
> + * @tcp_src: TCP source port
> + * @tcp_dst: TCP destination port
> + * @tcp_seq: TCP sequence number
> + * @tcp_ack: TCP Acknowledgment number
> + * @tcp_hlen: 4 bits TCP header Length/4, 4 bits reserved, 2 more bits reserved
> + * @tcp_flag: flags of TCP
> + * @tcp_win: TCP windows size
> + * @tcp_xsum: Checksum
> + * @tcp_ugr: Pointer to urgent data
> + */
> +struct ip_tcp_hdr {
> + u8 ip_hl_v;
> + u8 ip_tos;
> + u16 ip_len;
> + u16 ip_id;
> + u16 ip_off;
> + u8 ip_ttl;
> + u8 ip_p;
> + u16 ip_sum;
> + struct in_addr ip_src;
> + struct in_addr ip_dst;
> + u16 tcp_src;
> + u16 tcp_dst;
> + u32 tcp_seq;
> + u32 tcp_ack;
> + u8 tcp_hlen;
> + u8 tcp_flags;
> + u16 tcp_win;
> + u16 tcp_xsum;
> + u16 tcp_ugr;
> +} __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 */
> +#define TCP_MSS 1460 /* Max segment size */
> +#define TCP_SCALE 0x01 /* Scale */
> +
> +/**
> + * struct tcp_mss - TCP option structure for MSS (Max segment size)
> + * @kind: Field ID
> + * @len: Field length
> + * @mss: Segment size value
> + */
> +struct tcp_mss {
> + u8 kind;
> + u8 len;
> + u16 mss;
> +} __packed;
> +
> +/**
> + * struct tcp_scale - TCP option structure for Windows scale
> + * @kind: Field ID
> + * @len: Field length
> + * @scale: windows shift value used for networks with many hops.
> + * Typically 4 or more hops
> + */
> +struct tcp_scale {
> + u8 kind;
> + u8 len;
> + u8 scale;
> +} __packed;
> +
> +/**
> + * struct tcp_sack_p - TCP option structure for SACK permitted
> + * @kind: Field ID
> + * @len: Field length
> + */
> +struct tcp_sack_p {
> + u8 kind;
> + u8 len;
> +} __packed;
> +
> +/**
> + * struct sack_edges - structure for SACK edges
> + * @l: Left edge of stream
> + * @r: right edge of stream
> + */
> +struct sack_edges {
> + u32 l;
> + u32 r;
> +} __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 - TCP option structure for SACK
> + * @kind: Field ID
> + * @len: Field length
> + * @hill: L & R window edges
> + */
> +struct tcp_sack_v {
> + u8 kind;
> + u8 len;
> + struct sack_edges hill[TCP_SACK_HILLS];
> +} __packed;
> +
> +/**
> + * struct tcp_t_opt - TCP option structure for time stamps
> + * @kind: Field ID
> + * @len: Field length
> + * @t_snd: Sender timestamp
> + * @t_rcv: Receiver timestamp
> + */
> +struct tcp_t_opt {
> + u8 kind;
> + u8 len;
> + u32 t_snd;
> + u32 t_rcv;
> +} __packed;
> +
> +#define TCP_TSOPT_SIZE (sizeof(struct tcp_t_opt))
> +
> +/*
> + * ip tcp structure with options
> + */
> +
> +/**
> + * struct ip_tcp_hdr_o - IP + TCP header + TCP options
> + * @hdr: IP + TCP header
> + * @mss: TCP MSS Option
> + * @scale: TCP Windows Scale Option
> + * @sack_p: TCP Sack-Permitted Option
> + * @t_opt: TCP Timestamp Option
> + * @end: end of 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 - IP + TCP header + TCP options
> + * @hdr: IP + TCP header
> + * @t_opt: TCP Timestamp Option
> + * @sack_v: TCP SACK Option
> + * @end: end of options
> + */
> +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 - Pseudo Header
> + * @padding: pseudo hdr size = ip_tcp hdr size
> + * @p_src: Source IP address
> + * @p_dst: Destination IP address
> + * @rsvd: reserved
> + * @p: protocol
> + * @len: length of header
> + */
> +struct pseudo_hdr {
> + u8 padding[PSEUDO_PAD_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 tcp_build_pkt - union for building TCP/IP packet.
> + * @ph: pseudo header
> + * @ip: IP and TCP header plus TCP options
> + * @sack: IP and TCP header plus SACK options
> + * @raw: buffer
> + *
> + * 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;
> +
> +/**
> + * 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_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_CLOSED,
> + TCP_SYN_SENT,
> + TCP_ESTABLISHED,
> + TCP_CLOSE_WAIT,
> + TCP_CLOSING,
> + TCP_FIN_WAIT_1,
> + TCP_FIN_WAIT_2
> +};
> +
> +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);
> +
> +/**
> + * rxhand_tcp() - An incoming packet handler.
> + * @pkt: pointer to the application packet
> + * @dport: destination UDP port
> + * @sip: source IP address
> + * @sport: source UDP port
> + * @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);
> +
> +u16 tcp_set_pseudo_header(uchar *pkt, struct in_addr src, struct in_addr dest,
> + int tcp_len, int pkt_len);
> diff --git a/net/Kconfig b/net/Kconfig
> index 52e261884d..cb600fe5eb 100644
> --- a/net/Kconfig
> +++ b/net/Kconfig
> @@ -174,6 +174,22 @@ config BOOTP_MAX_ROOT_PATH_LEN
> help
> Select maximal length of option 17 root path.
>
> +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"
> + depends on PROT_TCP
> + help
> + TCP protocol with SACK. SACK means selective acknowledgements.
> + By turning this option on TCP will learn what segments are already
> + received. So that it improves TCP's retransmission efficiency.
> + This option should be turn on if you want to achieve the fastest
> + file transfer possible.
> +
> endif # if NET
>
> config SYS_RX_ETH_BUFFER
> diff --git a/net/Makefile b/net/Makefile
> index 6c812502d3..d131d1cb1a 100644
> --- a/net/Makefile
> +++ b/net/Makefile
> @@ -30,6 +30,7 @@ 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 b27b021d07..7878a9970b 100644
> --- a/net/net.c
> +++ b/net/net.c
> @@ -117,6 +117,7 @@
> #if defined(CONFIG_CMD_WOL)
> #include "wol.h"
> #endif
> +#include <net/tcp.h>
>
> /** BOOTP EXTENTIONS **/
>
> @@ -387,6 +388,8 @@ 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();
> @@ -833,6 +836,16 @@ 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)
> @@ -864,6 +877,14 @@ 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;
> }
> @@ -1273,6 +1294,15 @@ 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..8d338c72e8
> --- /dev/null
> +++ b/net/tcp.c
> @@ -0,0 +1,720 @@
> +// 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;
> +
> +static u32 tcp_seq_init;
> +static u32 tcp_ack_edge;
> +static u32 tcp_seq_max;
> +
> +static 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;
> +};
> +
> +static struct sack_r edge_a[TCP_SACK];
> +static unsigned int sack_idx;
> +static unsigned int prev_len;
> +
> +/*
> + * 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.
> + */
> +#define LEN_B_TO_DW(x) ((x) >> 2)
> +#define ROUND_TCPHDR_LEN(x) (LEN_B_TO_DW((x) + 3))
> +#define SHIFT_TO_TCPHDRLEN_FIELD(x) ((x) << 4)
> +#define GET_TCP_HDR_LEN_IN_BYTES(x) ((x) >> 2)
> +
> +/* TCP connection state */
> +static enum tcp_state current_tcp_state;
> +
> +/* Current TCP RX packet handler */
> +static rxhand_tcp *tcp_packet_handler;
> +
> +/**
> + * tcp_get_tcp_state() - get current TCP state
> + *
> + * Return: Current TCP state
> + */
> +enum tcp_state tcp_get_tcp_state(void)
> +{
> + return current_tcp_state;
> +}
> +
> +/**
> + * tcp_set_tcp_state() - set current TCP state
> + * @new_state: new TCP state
> + */
> +void tcp_set_tcp_state(enum tcp_state new_state)
> +{
> + current_tcp_state = new_state;
> +}
> +
> +static void dummy_handler(uchar *pkt, unsigned int dport,
> + struct in_addr sip, unsigned int sport,
> + unsigned int len)
> +{
> +}
> +
> +/**
> + * tcp_set_tcp_handler() - set a handler to receive data
> + * @f: handler
> + */
> +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;
> +}
> +
> +/**
> + * tcp_set_pseudo_header() - set TCP pseudo header
> + * @pkt: the packet
> + * @src: source IP address
> + * @dest: destinaion IP address
> + * @tcp_len: tcp length
> + * @pkt_len: packet length
> + *
> + * Return: the checksum of the packet
> + */
> +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] = 0;
> +
> + net_copy_ip((void *)&b->ph.p_src, &src);
> + net_copy_ip((void *)&b->ph.p_dst, &dest);
> + b->ph.rsvd = 0;
> + 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);
> +}
> +
> +/**
> + * net_set_ack_options() - set TCP options in acknowledge packets
> + * @b: the packet
> + *
> + * Return: TCP header length
> + */
> +int net_set_ack_options(union tcp_build_pkt *b)
> +{
> + b->sack.hdr.tcp_hlen = SHIFT_TO_TCPHDRLEN_FIELD(LEN_B_TO_DW(TCP_HDR_SIZE));
> +
> + 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 = 0;
> +
> + if (IS_ENABLED(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;
> + }
> +
> + b->sack.hdr.tcp_hlen = SHIFT_TO_TCPHDRLEN_FIELD(ROUND_TCPHDR_LEN(TCP_HDR_SIZE +
> + TCP_TSOPT_SIZE +
> + tcp_lost.len));
> + } else {
> + b->sack.sack_v.kind = 0;
> + b->sack.hdr.tcp_hlen = SHIFT_TO_TCPHDRLEN_FIELD(ROUND_TCPHDR_LEN(TCP_HDR_SIZE +
> + TCP_TSOPT_SIZE));
> + }
> +
> + /*
> + * This returns the actual rounded up length of the
> + * TCP header to add to the total packet length
> + */
> +
> + return GET_TCP_HDR_LEN_IN_BYTES(b->sack.hdr.tcp_hlen);
> +}
> +
> +/**
> + * net_set_ack_options() - set TCP options in SYN packets
> + * @b: the packet
> + */
> +void net_set_syn_options(union tcp_build_pkt *b)
> +{
> + if (IS_ENABLED(CONFIG_PROT_TCP_SACK))
> + 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 (IS_ENABLED(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;
> + }
> + b->ip.t_opt.kind = TCP_O_TS;
> + b->ip.t_opt.len = TCP_OPT_LEN_A;
> + loc_timestamp = get_ticks();
> + rmt_timestamp = 0;
> + b->ip.t_opt.t_snd = 0;
> + b->ip.t_opt.t_rcv = 0;
> + 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 = SHIFT_TO_TCPHDRLEN_FIELD(LEN_B_TO_DW(TCP_HDR_SIZE));
> +
> + 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 (current_tcp_state == TCP_SYN_SENT) { /* Too many SYNs */
> + action = TCP_FIN;
> + current_tcp_state = TCP_FIN_WAIT_1;
> + } else {
> + current_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;
> + current_tcp_state = TCP_FIN_WAIT_1;
> + 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",
> + &net_server_ip, &net_ip,
> + tcp_seq_num, tcp_ack_edge, 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",
> + &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 = 0;
> + b->ip.hdr.tcp_ugr = 0;
> +
> + 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;
> +}
> +
> +/**
> + * 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)
> +{
> + u32 idx_sack, sack_in;
> + u32 sack_end = TCP_SACK - 1;
> + u32 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;
> +
> + if (IS_ENABLED(CONFIG_PROT_TCP_SACK))
> + 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");
> + if (IS_ENABLED(CONFIG_PROT_TCP_SACK)) {
> + 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++;
> + if (IS_ENABLED(CONFIG_PROT_TCP_SACK))
> + 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 (IS_ENABLED(CONFIG_PROT_TCP_SACK) &&
> + hill < TCP_SACK_HILLS)
> + tcp_lost.hill[hill].r =
> + edge_a[sack_in].se.r;
> + if (IS_ENABLED(CONFIG_PROT_TCP_SACK) &&
> + 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 (!IS_ENABLED(CONFIG_PROT_TCP_SACK) || tcp_lost.len <= TCP_OPT_LEN_2)
> + sack_idx = 0;
> +}
> +
> +/**
> + * tcp_parse_options() - parsing TCP options
> + * @o: pointer to the option field.
> + * @o_len: length of the option field.
> + */
> +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])
> + return; /* Finished processing options */
> +
> + switch (p[0]) {
> + case TCP_O_END:
> + return;
> + case TCP_O_MSS:
> + case TCP_O_SCL:
> + case TCP_P_SACK:
> + case TCP_V_SACK:
> + break;
> + case TCP_O_TS:
> + tsopt = (struct tcp_t_opt *)p;
> + rmt_timestamp = tsopt->t_snd;
> + return;
> + }
> +
> + /* Process optional NOPs */
> + if (p[0] == TCP_O_NOP)
> + p++;
> + }
> +}
> +
> +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;
> + 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;
> + current_tcp_state = TCP_CLOSED;
> + net_set_state(NETLOOP_FAIL);
> + debug_cond(DEBUG_INT_STATE, "TCP Reset %x\n", tcp_flags);
> + return TCP_RST;
> + }
> +
> + 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)
> + 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;
> + 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) {
> + 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) &&
> + (!IS_ENABLED(CONFIG_PROT_TCP_SACK) ||
> + tcp_lost.len <= TCP_OPT_LEN_2)) {
> + action = action | TCP_FIN | TCP_PUSH | TCP_ACK;
> + current_tcp_state = TCP_CLOSE_WAIT;
> + } else if (tcp_ack) {
> + action = TCP_DATA;
> + }
> +
> + if (tcp_syn)
> + action = TCP_ACK + TCP_RST;
> + else if (tcp_push)
> + action = action | TCP_PUSH;
> + break;
> + case TCP_CLOSE_WAIT:
> + debug_cond(DEBUG_INT_STATE, "TCP_CLOSE_WAIT (%x)\n", tcp_flags);
> + action = TCP_DATA;
> + break;
> + case TCP_FIN_WAIT_2:
> + debug_cond(DEBUG_INT_STATE, "TCP_FIN_WAIT_2 (%x)\n", tcp_flags);
> + if (tcp_ack) {
> + action = TCP_PUSH | TCP_ACK;
> + current_tcp_state = TCP_CLOSED;
> + puts("\n");
> + } else if (tcp_syn) {
> + action = TCP_DATA;
> + } else if (tcp_fin) {
> + action = TCP_DATA;
> + }
> + 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;
> + current_tcp_state = TCP_FIN_WAIT_2;
> + }
> + if (tcp_syn)
> + action = TCP_RST;
> + 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);
> + if (tcp_ack) {
> + action = TCP_PUSH;
> + current_tcp_state = TCP_CLOSED;
> + puts("\n");
> + } else if (tcp_syn) {
> + action = TCP_RST;
> + } else if (tcp_fin) {
> + action = TCP_DATA;
> + }
> + break;
> + }
> + return action;
> +}
> +
> +/**
> + * rxhand_tcp_f() - process receiving data and call data handler.
> + * @b: the packet
> + * @pkt_len: the length of packet.
> + */
> +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, tcp_ack_num;
> + struct in_addr action_and_state;
> + int tcp_hdr_len, 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);
> +
> + b->ip.hdr.ip_src = net_server_ip;
> + b->ip.hdr.ip_dst = net_ip;
> + b->ip.hdr.ip_sum = 0;
> + 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 = 0;
> + 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 = GET_TCP_HDR_LEN_IN_BYTES(b->ip.hdr.tcp_hlen);
> + 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);
> +
> + 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);
> + }
> +}
> --
> 2.35.1
>
Reviewed-by: Ramon Fried <rfried.dev at gmail.com>
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