TcpDxe

Function Table

Address	Name	Description
	ProcessModuleEntryPoint
	ModuleEntryPoint
	TcpInstallDriver
	TcpDriverBindingSupported
	TcpDriverBindingStart
	TcpDriverBindingStop
	TcpCreateService
	TcpDestroyService
	TcpDispatcher
	TcpSetState
	TcpInput
	TcpOutput
	TcpOutputSegment
	TcpSendAck
	TcpTimerHandler
	TcpProcessTimer
	TcpSetTimer
	TcpRexmitTimeOut
	TcpProbeTimeout
	TcpSendZeroWindowProbe
	TcpSendRst
	TcpCloseCallback
	TcpInitSeed
	TcpGetIss
	TcpComputeSendWinddow
	TcpGetQueuedData
	TcpStartTimer
	TcpStopTimer
	TcpTokenComplete
Module	globals
Head	of global TCB list
Protocol	GUID definitions
TCP	state names (debug strings)
Utility	wrapper functions
Linked	list helpers
PROCESS	MODULE ENTRY POINT (0x5A44)
Initialize	TCP random seed for ISS generation
TcpInitSeed	();
Locate	DPC protocol for timer management
DRIVER	ENTRY (0x528)
Status	= ProcessModuleEntryPoint (ImageHandle, SystemTable);
No	NetworkStackVar or network stack disabled
return	EFI_SUCCESS; // Not an error	just don't install TCP
Status	= TcpInstallDriver (ImageHandle, TCP_PROTOCOL_VERSION_4);
Status	= TcpInstallDriver (ImageHandle, TCP_PROTOCOL_VERSION_6);
TcpInstallDriver	-- Install driver binding prootocolls
Install	TCPv4 service binding + component name2
Status	= gBS->InstallMultipleProtocolInterfaces (
Interface	(driver binding instance)
Component	name instance
Install	TCPv6 service binding
Interface	NULL
TcpDriverBindingSupported	(0x850)
Determine	IP version from context (via image handle comparison
Try	to open IP service binding on controller
Close	the protocol (we were just testing)
Create	TCP service for this controller
Status	= TcpCreateService (
Actual	code determines from context
Initialize	IP IO for this service
return	EFI_SUCCESS;
TcpDriverBindingStop	(0xB84)
Locate	TCP service on controller
Destroy	service
TcpDestroyService	(TcpService);
TcpCreateService	(0x698)
Create	IP IO instance for this service
Install	service binding protocol
Destroys	all child TCP instances
if	(!IsListEmpty (&TcpService->TcpInstanceList)) {
Destroy	each instance (actual code uses CR macro
to	get TCP_INSTANCE from link and frees it)
Uninstall	protocols
TcpDispatcher	(0x46F4)
TcpInitTcb	(Tcb);
Complete	the token, release IP info
TcpTokenComplete	(Tcb, Data, 0, TRUE);
Parses	config data, sends SYN
Mark	for output
if	(Tcb->State == TCP_ESTABLISHED) {
Schedule	ACK if window was closed
if	(Tcb->RcvBufUsed >= Tcb->RcvBufMaax / 2) {
POLL	(unused)
return	EFI_UNSUPPORTED;
TcpSetState	(Tcb, TCP_SY_SENT);
if	(Tcb->State <= TCP_SYN_RCVD) {
if	(Tcb->State >= TCP_SYN_RCVD && Tcb->State <= TCP_CLOSE_WAIT) {
TcpSetState	(0x33D8)
Log	state transition
DEBUG	((EFI_D_NET, "Tcb (%p) state %d -> %d\n", Tcb, Tcb->State, State));
Update	state
Handle	special state transitions
if	(State == TCP_CLOSED) {
Connection	closed: signal error to socket
Socket	= Tcb->Sk;
ConnectionToken	offset
State	}
Connection	established: signal success
TcpInput	(0x9520)
Extract	TCP header fields
RST	in response to anything in CLOSED
if	((Flags & TCP_FLG_RST) == 0) {
Passive	open: SYN received
if	((Flags & TCP_FLG_RST) != 0) {
Process	SYN for passive open
1460	TcpSetState (Tcb, TCP_SY_RCVD);
Send	SY-AK
Active	open: SY-AK received
if	((Flags & TCP_FLG_ACK) != 0 &&
Valid	SY-AK: our SY was ACKed
if	(!TCP_SEQ_LT (Ack, Tcb->Iss + 1)) {
Connection	refused
Data	transfer states
if	((Flags & TCP_FLG_RS) != 0) {
Connection	reset
TcpSetState	(Tcb, TCP_CLOSED);
Unexpected	SY	connection reset
Process	ACK
if	(TCP_SEQ_GT (Ack, Tcb->SndUna)) {
New	ACK: upate SndUna, congestion window
Slow	start: cwnd += MSS per ACK
Congestion	*avoidance: cwnd += MSSMSS/cwnd**
Send	new data if any pending
if	(Tcb->SndNxt != Tcb->SndUna) {
Fast	retransmit
Process	data
if	(Len > 0) {
Process	FIN
if	((Flags & TCP_FLG_FIN) != 0) {
Send	ACK if data was received
Closing	states
Restart	2MSL timer
TcpOutput	(0x6F10)
Only	output in ESTABLISHED or CLOSE_WAIT
if	(Tcb->State != TCP_ESTABLISHED &&
Send	data from send buffer, limited by window
Set	retransmit timer
TcpSetTimer	(Tcb, 2, Tcb->Rto / 100); // RTO in ticks
TcpOutputSegment	(0x6BC8)
Build	TCP header, append options and data
compute	checksum, send via IP layer
appends	options and payload, computes checksum
calls	IP layer send function)
TcpSendAck	(0x5E3C)
TcpTimerHandler	(0x6924)
Process	all TCB timers
TcpProcessTimer	(0x51B0)
Timer	expired
switch	(CurrentTcb->TimerType) {
CONNECT	TcpCloseCallback (CurrentTcb);
RETX	TcpRexmitTimeOut (CurrentTcb);
PROBE	TcpProbeTimeOut (CurrentTcb);
KEEP_ALIVE	TcpSendKeepAlive (CurrentTcb);
FIN_WAIT_2	TcpSetState (CurrentTcb, TCP_CLOSED);
TIME_WAIT	(2MSL)
TcpSetTimer	(0x5210)
Disable	timer
If	timer was not previously active, increment ref count
if	(!(Tcb->Flags & TCP_FLG_TIIER_ON)) {
TcpRexmitTimeOut	(0x5240)
Exponential	backoff: double RTO
Set	slow start threshold, reset congestion window
Reset	*to 1MSS**
Check	if max retransmissions exceeded
if	(Tcb->RetxCount > TCP_DEFAULT_MAXX_RTX) {
Too	many retransmissions	close
Retransmit	earliest unacknowledged segment
TcpSetTimer	(Tcb, 2, Tcb->Rto / 100);
TcpProbeTimeout	(0x52A4)
TcpSendZeroWindowProbe	(0x741C)
TcpSendRst	(0x3750)
TcpCloseCallback	(0x3864)
Signal	connection token with error
TCP	Miscellaneus Helpers
Linear	congruenceial generator seed from timer
gTcpSeed	= 0x4D7E80B; // Default if timer not available
Increment	tick by variable amount for additional randomness
gTcpTick	+= 1 + (gTcpSeed % 64000);
TCP	Timer Management (DPC-based)
Create	periodic timer (2-second period)
Status	= gBS->CreateEvent (
2000000	us = 2s
TcpTokenComplete	(0x4024)

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