TCP

Transmission Control Protocol driver. More...

Functions
ushort	tcpAlloc (void)
ushort	tcpChksum (struct packet *pkt, ushort len, struct netaddr *src, struct netaddr *dst)
devcall	tcpClose (device *devptr)
devcall	tcpControl (device *devptr, int func, long arg1, long arg2)
struct tcb *	tcpDemux (ushort dstpt, ushort srcpt, struct netaddr *dstip, struct netaddr *srcip)
devcall	tcpFree (struct tcb *tcbptr)
devcall	tcpGetc (device *devptr)
devcall	tcpInit (device *devptr)
devcall	tcpOpen (device *devptr, va_list ap)
devcall	tcpOpenActive (struct tcb *tcbptr)
devcall	tcpPutc (device *devptr, char ch)
devcall	tcpRead (device *devptr, void *buf, uint len)
int	tcpRecv (struct packet *pkt, struct netaddr *src, struct netaddr *dst)
int	tcpRecvAck (struct packet *pkt, struct tcb *tcbptr)
int	tcpRecvData (struct packet *pkt, struct tcb *tcbptr)
int	tcpRecvListen (struct packet *pkt, struct tcb *tcbptr, struct netaddr *src)
int	tcpRecvOpts (struct packet *pkt, struct tcb *tcbptr)
int	tcpRecvOther (struct packet *pkt, struct tcb *tcbptr)
int	tcpRecvRtt (struct tcb *tcbptr)
int	tcpRecvSynsent (struct packet *pkt, struct tcb *tcbptr)
bool	tcpRecvValid (struct packet *pkt, struct tcb *tcbptr)
int	tcpSend (struct tcb *tcbptr, uchar ctrl, uint seqnum, uint acknum, uint datastart, ushort datalen)
int	tcpSendAck (struct tcb *tcbptr)
int	tcpSendData (struct tcb *tcbptr)
int	tcpSendPersist (struct tcb *tcbptr)
int	tcpSendRst (struct packet *pkt, struct netaddr *src, struct netaddr *dst)
int	tcpSendRxt (struct tcb *tcbptr)
int	tcpSendSyn (struct tcb *tcbptr)
ushort	tcpSendWindow (struct tcb *tcbptr)
tcpseq	tcpSeqdiff (tcpseq first, tcpseq second)
int	tcpSetup (struct tcb *tcbptr)
void	tcpStat (struct tcb *tcbptr)
thread	tcpTimer (void)
devcall	tcpTimerPurge (struct tcb *tcbptr, uchar type)
int	tcpTimerRemain (struct tcb *tcbptr, uchar type)
devcall	tcpTimerSched (int time, struct tcb *tcbptr, uchar type)
void	tcpTimerTrigger (uchar type, struct tcb *tcbptr)
devcall	tcpWrite (device *devptr, void *buf, uint len)

Detailed Description

Transmission Control Protocol driver.

This module provides an interface to the Transmission Control Protocol (TCP).

Function Documentation

ushort tcpAlloc

(

void

)

Allocate an available tcp device.

Returns

device number for a tcp device, SYSERR if none are free

devcall tcpClose

(

device *

devptr

)

Close a TCP device.

Parameters

devptr

TCP device table entry

Returns

OK if TCP is closed properly, otherwise SYSERR

devcall tcpControl	(	device *	devptr,
		int	func,
		long	arg1,
		long	arg2
	)

Control function for TCP devices.

Parameters

devptr	ethernet device table entry
func	control function to execute
arg1	first argument for the control function
arg2	second argument for the control function

Returns

the result of the control function

struct tcb* tcpDemux	(	ushort	dstpt,
		ushort	srcpt,
		struct netaddr *	dstip,
		struct netaddr *	srcip
	)

Locate the TCP socket for a TCP packet

Parameters

dstpt	destination port of the TCP packet
srcpt	source port of the TCP packet
dstip	destination IP of the TCP packet
srcip	source IP of the TCP packet

Returns

most completely matched socket, NULL if no match

devcall tcpFree

(

struct tcb *

tcbptr

)

Delete a TCB.

Parameters

tcbptr

pointer to transmission control block for connection TCB mutex is already held

devcall tcpGetc

(

device *

devptr

)

Read into a single octet from TCP.

Parameters

devptr

TCP device table entry

Returns

character read from TCP

devcall tcpInit

(

device *

devptr

)

Initialize TCP structures.

Parameters

devptr

tcp device table entry

Returns

OK if device is initialized

devcall tcpOpen	(	device *	devptr,
		va_list	ap
	)

Associate a tcp with a network device.

Parameters

devptr	tcp device table entry
ap	2nd argument is the local IP address 3rd argument is the remote IP address 4th argument is the local port (auto-assigned if zero) 5th argument is the remote port (ignored if zero) 6th argument is the mode (TCP_ACTIVE or TCP_PASSIVE)

Returns

OK if TCP is opened properly, otherwise SYSERR

devcall tcpOpenActive

(

struct tcb *

tcbptr

)

Actively opens a TCP connection.

Parameters

tcbptr

TCB for connection

Returns

OK if tcp is opened properly, otherwise SYSERR

Precondition

-condition TCB mutex is already held

Postcondition

-condition TCB mutex is still held

devcall tcpPutc	(	device *	devptr,
		char	ch
	)

Write a single octet to send via TCP.

Parameters

devptr	TCP device table entry
ch	character to output

Returns

ch as an unsigned char cast to an int on success; SYSERR on failure.

devcall tcpRead	(	device *	devptr,
		void *	buf,
		uint	len
	)

Read into a buffer from TCP.

Parameters

devptr	TCP device table entry
buf	buffer to read octets into
len	size of the buffer

Returns

count of octets read

int tcpRecv	(	struct packet *	pkt,
		struct netaddr *	src,
		struct netaddr *	dst
	)

Processes an incoming TCP packet. See RFC 793, pg 65 for an overview of the TCP packet arrival algorithm.

Parameters

pkt	incoming packet
src	source of incoming packet
dst	destination of incoming packet

int tcpRecvAck	(	struct packet *	pkt,
		struct tcb *	tcbptr
	)

Process an ackowledgement of data in an incoming TCP segment for a connection which has been fully established.

Parameters

pkt	incoming packet
tcbptr	pointer to transmission control block for connection TCB mutex is already held TCB mutex is still held

int tcpRecvData	(	struct packet *	pkt,
		struct tcb *	tcbptr
	)

Processes the data in an incoming packet for a TCP connection. Function based on RFC 763, pg 73-76.

Parameters

pkt	incoming packet
tcbptr	pointer to transmission control block for connection

Precondition

-condition TCB mutex is already held

Postcondition

-condition TCB mutex is still held

int tcpRecvListen	(	struct packet *	pkt,
		struct tcb *	tcbptr,
		struct netaddr *	src
	)

Processes an incoming packet for a TCP connection in the LISTEN state.

Parameters

pkt	incoming packet
tcbptr	pointer to transmission control block for connection
src	source IP address

Returns

OK

Precondition

-condition TCB mutex is already held

int tcpRecvOpts	(	struct packet *	pkt,
		struct tcb *	tcbptr
	)

Processes the options in an incoming packet for a TCP connection.

Parameters

pkt	incoming packet
tcbptr	pointer to transmission control block for connection

Returns

OK

Precondition

-condition TCB mutex is already held

Postcondition

-condition TCB mutex is still held

int tcpRecvOther	(	struct packet *	pkt,
		struct tcb *	tcbptr
	)

Processes an incoming packet for a TCP connection in the SYNRECV, ESTAB, FINWT1, FINWT2, CLOSEWT, CLOSING, LASTACK, or TIMEWT state. Function based on RFC 763, pg 69-73.

Parameters

pkt	incoming packet
tcbptr	pointer to transmission control block for connection

Precondition

-condition TCB mutex is already held

Postcondition

-condition TCB mutex is still held

int tcpRecvRtt

(

struct tcb *

tcbptr

)

Handle round trip time estimates based on an incoming acknowledgement.

Parameters

tcbptr

pointer to transmission control block for connection

Returns

OK TCB mutex is already held TCB mutex is still held

int tcpRecvSynsent	(	struct packet *	pkt,
		struct tcb *	tcbptr
	)

Processes an incoming packet for a TCP connection in the SYNSENT state. Function based on RFC 763, pg 66-68.

Parameters

pkt	incoming packet
tcbptr	pointer to transmission control block for connection

Returns

OK or TCP_ERR_SNDRST

Precondition

-condition TCB mutex is already held

bool tcpRecvValid	(	struct packet *	pkt,
		struct tcb *	tcbptr
	)

Checks if an incoming TCP segment is valid.

Parameters

pkt	incoming packet
tcbptr	pointer to transmission control block for connection TCB mutex is already held TCB mutex is still held

int tcpSend	(	struct tcb *	tcbptr,
		uchar	ctrl,
		uint	seqnum,
		uint	acknum,
		uint	datastart,
		ushort	datalen
	)

Sends a TCP packet for a TCP connection.

Parameters

tcbptr	pointer to the transmission control block for connection
ctrl	control flags to be set
seqnum	sequence number for the packet
acknum	acknowledgement number for the packet
data	data to be included in the packet, NULL if no data
datalen	length of the data, 0 if no data

Precondition

-condition TCB mutex is already held

Postcondition

-condition TCB mutex is still held

int tcpSendAck

(

struct tcb *

tcbptr

)

Sends an ACK packet to ackowledge all received data for a TCP connection.

Parameters

tcpptr

pointer to the transmission control block for connection

Precondition

-condition TCB mutex is already held

Postcondition

-condition TCB mutex is still held

int tcpSendData

(

struct tcb *

tcbptr

)

Sends pending outbound data (including SYN and FIN) for a TCP connection, if new data is ready for transmission.

Parameters

tcpptr

pointer to the transmission control block for connection

Returns

number of octets sent

Precondition

-condition TCB mutex is already held

Postcondition

-condition TCB mutex is still held

< amount of window filled with data pending ACK

< amount of data pending ACK or transmission

int tcpSendPersist

(

struct tcb *

tcbptr

)

Send a segment to probe a receiver who advertised a window size of 0.

Parameters

tcpptr

pointer to the transmission control block for connection

Returns

number of octets sent

int tcpSendRst	(	struct packet *	pkt,
		struct netaddr *	src,
		struct netaddr *	dst
	)

Sends a reset in response to an incorrect TCP packet

Parameters

pkt	incoming packet which requires a reset response
src	source IP address of the packet
dst	destination IP address of the packet

int tcpSendRxt

(

struct tcb *

tcbptr

)

Retransmitts a segment of pending outbound data (including SYN and FIN) for a TCP connection.

Parameters

tcpptr

pointer to the transmission control block for connection

Returns

number of octets sent

< amount of data pending ACK

int tcpSendSyn

(

struct tcb *

tcbptr

)

Sends an SYN packet to establish a TCP connection.

Parameters

tcpptr

pointer to the transmission control block for connection

Precondition

-condition TCB mutex is already held

Postcondition

-condition TCB mutex is still held

ushort tcpSendWindow

(

struct tcb *

tcbptr

)

Calculates the window size to advertise in an outgoing TCP packet.

Parameters

tcbptr

pointer to transmission control block for connection

Precondition

-condition TCB mutex is already held

Postcondition

-condition TCB mutex is still held

tcpseq tcpSeqdiff	(	tcpseq	first,
		tcpseq	second
	)

Calculates the difference between two sequence numbers.

Parameters

first	sequence number that occurs first
second	sequence number that occurs second

Returns

difference between two sequence numbers

int tcpSetup

(

struct tcb *

tcbptr

)

Intializes a transmission control block. tcbptr TCB for connection

Returns

OK if TCB is initialized properly, otherwise SYSERR

Precondition

-condition TCB mutex is already held

Postcondition

-condition TCB mutex is still held

void tcpStat

(

struct tcb *

tcbptr

)

Transmission Control Protocol status command.

Parameters

tcbptr

pointer to transmission control block

thread tcpTimer

(

void

)

TCP timer process to manage timeout and retransmit events.

devcall tcpTimerPurge	(	struct tcb *	tcbptr,
		uchar	type
	)

Remove all TCP timer events for a particular TCB.

Parameters

tcbptr	TCB for which to remove all events
type	type of events to remove, all types are removed if NULL

Returns

the time elapsed for the first remvoed event, SYSERR if no events were removed

int tcpTimerRemain	(	struct tcb *	tcbptr,
		uchar	type
	)

Determine time reamining for a TCP timer event for a particular TCB.

Parameters

tcbptr	TCB to which event corresponds
type	type of timer event

Returns

time remaining for event, 0 if no event exists

devcall tcpTimerSched	(	int	time,
		struct tcb *	tcbptr,
		uchar	type
	)

Schedule TCP timer events.

Parameters

time	milliseconds before timer triggers
tcbptr	TCB with which event is associated
type	type of timer event

Returns

OK if event is successfully scheduled, otherwise SYSERR

void tcpTimerTrigger	(	uchar	type,
		struct tcb *	tcbptr
	)

Processes TCP timer events.

Parameters

evtptr

timer event to process

devcall tcpWrite	(	device *	devptr,
		void *	buf,
		uint	len
	)

Write into a buffer to send via TCP.

Parameters

devptr	TCP device table entry
buf	buffer to read octets into
len	size of the buffer

Returns

count of octets written