blob: b0cc8a1fe3ed6d65ab244f497ac338ed2bb7a58a [file] [log] [blame]
// 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 <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 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, u16 dport,
struct in_addr sip, u16 sport,
u32 tcp_seq_num, u32 tcp_ack_num,
u8 action, 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=%u, ak=%u)\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_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=%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=%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;
debug_cond(DEBUG_DEV_PKT,
"TCP Hdr:FIN ACK PSH(%pI4, %pI4, s=%u, a=%u, A=%x)\n",
&net_server_ip, &net_ip,
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=%u, a=%u, 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_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 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
*/
void tcp_hole(u32 tcp_seq_num, u32 len)
{
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_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 | TCP_SYN_RECEIVED %x, %u\n",
tcp_flags, tcp_seq_num);
if (tcp_fin) {
action = action | TCP_PUSH;
current_tcp_state = TCP_CLOSE_WAIT;
} 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 (payload_len > 0) {
tcp_hole(tcp_seq_num, payload_len);
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) {
tcp_ack_edge++;
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;
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;
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=%u,Ack=%u,Pay%d)\n",
tcp_action, tcp_seq_num, 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=%u,Ack=%u,Pay=%d)\n",
tcp_action, tcp_ack_num, tcp_ack_edge, 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_ack_num, tcp_ack_edge);
}
}