Transmission Control Protocol for IP. More...

Functions
static u16_t	tcp_new_port (void)
	A nastly hack featuring 'goto' statements that allocates a new TCP local port.
void	tcp_tmr (void)
	Called periodically to dispatch TCP timers.
static err_t	tcp_close_shutdown (struct tcp_pcb *pcb, u8_t rst_on_unacked_data)
	Closes the TX side of a connection held by the PCB.
err_t	tcp_close (struct tcp_pcb *pcb)
	Closes the connection held by the PCB.
err_t	tcp_shutdown (struct tcp_pcb *pcb, int shut_rx, int shut_tx)
	Causes all or part of a full-duplex connection of this PCB to be shut down.
void	tcp_abandon (struct tcp_pcb *pcb, int reset)
	Abandons a connection and optionally sends a RST to the remote host.
void	tcp_abort (struct tcp_pcb *pcb)
	Aborts the connection by sending a RST (reset) segment to the remote host.
err_t	tcp_bind (struct tcp_pcb pcb, ip_addr_t ipaddr, u16_t port)
	Binds the connection to a local portnumber and IP address.
static err_t	tcp_accept_null (void arg, struct tcp_pcb pcb, err_t err)
	Default accept callback if no accept callback is specified by the user.
struct tcp_pcb *	tcp_listen_with_backlog (struct tcp_pcb *pcb, u8_t backlog)
	Set the state of the connection to be LISTEN, which means that it is able to accept incoming connections.
u32_t	tcp_update_rcv_ann_wnd (struct tcp_pcb *pcb)
	Update the state that tracks the available window space to advertise.
void	tcp_recved (struct tcp_pcb *pcb, u16_t len)
	This function should be called by the application when it has processed the data.
err_t	tcp_connect (struct tcp_pcb pcb, ip_addr_t ipaddr, u16_t port, tcp_connected_fn connected)
	Connects to another host.
void	tcp_slowtmr (void)
	Called every 500 ms and implements the retransmission timer and the timer that removes PCBs that have been in TIME-WAIT for enough time.
void	tcp_fasttmr (void)
	Is called every TCP_FAST_INTERVAL (250 ms) and process data previously "refused" by upper layer (application) and sends delayed ACKs.
void	tcp_segs_free (struct tcp_seg *seg)
	Deallocates a list of TCP segments (tcp_seg structures).
void	tcp_seg_free (struct tcp_seg *seg)
	Frees a TCP segment (tcp_seg structure).
void	tcp_setprio (struct tcp_pcb *pcb, u8_t prio)
	Sets the priority of a connection.
struct tcp_seg *	tcp_seg_copy (struct tcp_seg *seg)
	Returns a copy of the given TCP segment.
err_t	tcp_recv_null (void arg, struct tcp_pcb pcb, struct pbuf *p, err_t err)
	Default receive callback that is called if the user didn't register a recv callback for the pcb.
static void	tcp_kill_prio (u8_t prio)
	Kills the oldest active connection that has lower priority than prio.
static void	tcp_kill_timewait (void)
	Kills the oldest connection that is in TIME_WAIT state.
struct tcp_pcb *	tcp_alloc (u8_t prio)
	Allocate a new tcp_pcb structure.
struct tcp_pcb *	tcp_new (void)
	Creates a new TCP protocol control block but doesn't place it on any of the TCP PCB lists.
void	tcp_arg (struct tcp_pcb pcb, void arg)
	Used to specify the argument that should be passed callback functions.
void	tcp_recv (struct tcp_pcb *pcb, tcp_recv_fn recv)
	Used to specify the function that should be called when a TCP connection receives data.
void	tcp_sent (struct tcp_pcb *pcb, tcp_sent_fn sent)
	Used to specify the function that should be called when TCP data has been successfully delivered to the remote host.
void	tcp_err (struct tcp_pcb *pcb, tcp_err_fn err)
	Used to specify the function that should be called when a fatal error has occured on the connection.
void	tcp_accept (struct tcp_pcb *pcb, tcp_accept_fn accept)
	Used for specifying the function that should be called when a LISTENing connection has been connected to another host.
void	tcp_poll (struct tcp_pcb *pcb, tcp_poll_fn poll, u8_t interval)
	Used to specify the function that should be called periodically from TCP.
void	tcp_pcb_purge (struct tcp_pcb *pcb)
	Purges a TCP PCB.
void	tcp_pcb_remove (struct tcp_pcb *pcblist, struct tcp_pcb pcb)
	Purges the PCB and removes it from a PCB list.
u32_t	tcp_next_iss (void)
	Calculates a new initial sequence number for new connections.
u16_t	tcp_eff_send_mss (u16_t sendmss, ip_addr_t *addr)
	Calcluates the effective send mss that can be used for a specific IP address by using ip_route to determin the netif used to send to the address and calculating the minimum of TCP_MSS and that netif's mtu (if set).
void	tcp_debug_print (struct tcp_hdr *tcphdr)
	Print a tcp header for debugging purposes.
void	tcp_debug_print_state (enum tcp_state s)
	Print a tcp state for debugging purposes.
void	tcp_debug_print_flags (u8_t flags)
	Print tcp flags for debugging purposes.
void	tcp_debug_print_pcbs (void)
	Print all tcp_pcbs in every list for debugging purposes.
s16_t	tcp_pcbs_sane (void)
	Check state consistency of the tcp_pcb lists.
Variables
struct tcp_pcb *	tcp_bound_pcbs
	List of all TCP PCBs bound but not yet (connected \|\| listening)
union tcp_listen_pcbs_t	tcp_listen_pcbs
	List of all TCP PCBs in LISTEN state.
struct tcp_pcb *	tcp_active_pcbs
	List of all TCP PCBs that are in a state in which they accept or send data.
struct tcp_pcb *	tcp_tw_pcbs
	List of all TCP PCBs in TIME-WAIT state.
struct tcp_pcb **const	tcp_pcb_lists []
	An array with all (non-temporary) PCB lists, mainly used for smaller code size.
struct tcp_pcb *	tcp_tmp_pcb
	Only used for temporary storage.
static u8_t	tcp_timer
	Timer counter to handle calling slow-timer from tcp_tmr()

Detailed Description

Transmission Control Protocol for IP.

This file contains common functions for the TCP implementation, such as functinos for manipulating the data structures and the TCP timer functions. TCP functions related to input and output is found in tcp_in.c and tcp_out.c respectively.

Definition in file lwip_tcp.c.

Function Documentation

void tcp_abandon	(	struct tcp_pcb *	pcb,
		int	reset
	)

Abandons a connection and optionally sends a RST to the remote host.

Deletes the local protocol control block. This is done when a connection is killed because of shortage of memory.

Parameters:

pcb	the tcp_pcb to abort
reset	boolean to indicate whether a reset should be sent

Definition at line 318 of file lwip_tcp.c.

void tcp_abort ( struct tcp_pcb * pcb )

Aborts the connection by sending a RST (reset) segment to the remote host.

The pcb is deallocated. This function never fails.

ATTENTION: When calling this from one of the TCP callbacks, make sure you always return ERR_ABRT (and never return ERR_ABRT otherwise or you will risk accessing deallocated memory or memory leaks!

Parameters:

pcb	the tcp pcb to abort

Definition at line 380 of file lwip_tcp.c.

void tcp_accept	(	struct tcp_pcb *	pcb,
		tcp_accept_fn	accept
	)

Used for specifying the function that should be called when a LISTENing connection has been connected to another host.

Parameters:

pcb	tcp_pcb to set the accept callback
accept	callback function to call for this pcb when LISTENing connection has been connected to another host

Definition at line 1332 of file lwip_tcp.c.

static err_t tcp_accept_null	(	void *	arg,
		struct tcp_pcb *	pcb,
		err_t	err
	)		`[static]`

Default accept callback if no accept callback is specified by the user.

Definition at line 458 of file lwip_tcp.c.

struct tcp_pcb* tcp_alloc ( u8_t prio ) [read]

Allocate a new tcp_pcb structure.

Parameters:

prio	priority for the new pcb

Returns:: a new tcp_pcb that initially is in state CLOSED

Definition at line 1180 of file lwip_tcp.c.

void tcp_arg	(	struct tcp_pcb *	pcb,
		void *	arg
	)

Used to specify the argument that should be passed callback functions.

Parameters:

pcb	tcp_pcb to set the callback argument
arg	void pointer argument to pass to callback functions

Definition at line 1277 of file lwip_tcp.c.

err_t tcp_bind	(	struct tcp_pcb *	pcb,
		ip_addr_t *	ipaddr,
		u16_t	port
	)

Binds the connection to a local portnumber and IP address.

If the IP address is not given (i.e., ipaddr == NULL), the IP address of the outgoing network interface is used instead.

Parameters:

pcb	the tcp_pcb to bind (no check is done whether this pcb is already bound!)
ipaddr	the local ip address to bind to (use IP_ADDR_ANY to bind to any local address
port	the local port to bind to

Returns:: ERR_USE if the port is already in use ERR_VAL if bind failed because the PCB is not in a valid state ERR_OK if bound

Definition at line 400 of file lwip_tcp.c.

err_t tcp_close ( struct tcp_pcb * pcb )

Closes the connection held by the PCB.

Listening pcbs are freed and may not be referenced any more. Connection pcbs are freed if not yet connected and may not be referenced any more. If a connection is established (at least SYN received or in a closing state), the connection is closed, and put in a closing state. The pcb is then automatically freed in tcp_slowtmr(). It is therefore unsafe to reference it (unless an error is returned).

Parameters:

pcb	the tcp_pcb to close

Returns:: ERR_OK if connection has been closed another err_t if closing failed and pcb is not freed

Definition at line 252 of file lwip_tcp.c.

static err_t tcp_close_shutdown	(	struct tcp_pcb *	pcb,
		u8_t	rst_on_unacked_data
	)		`[static]`

Closes the TX side of a connection held by the PCB.

For tcp_close(), a RST is sent if the application didn't receive all data (tcp_recved() not called for all data passed to recv callback).

Listening pcbs are freed and may not be referenced any more. Connection pcbs are freed if not yet connected and may not be referenced any more. If a connection is established (at least SYN received or in a closing state), the connection is closed, and put in a closing state. The pcb is then automatically freed in tcp_slowtmr(). It is therefore unsafe to reference it.

Parameters:

pcb	the tcp_pcb to close

Returns:: ERR_OK if connection has been closed another err_t if closing failed and pcb is not freed

Definition at line 138 of file lwip_tcp.c.

err_t tcp_connect	(	struct tcp_pcb *	pcb,
		ip_addr_t *	ipaddr,
		u16_t	port,
		tcp_connected_fn	connected
	)

Connects to another host.

The function given as the "connected" argument will be called when the connection has been established.

Parameters:

pcb	the tcp_pcb used to establish the connection
ipaddr	the remote ip address to connect to
port	the remote tcp port to connect to
connected	callback function to call when connected (or on error)

Returns:: ERR_VAL if invalid arguments are given ERR_OK if connect request has been sent other err_t values if connect request couldn't be sent

Definition at line 649 of file lwip_tcp.c.

void tcp_debug_print ( struct tcp_hdr * tcphdr )

Print a tcp header for debugging purposes.

Parameters:

tcphdr pointer to a struct tcp_hdr

Definition at line 1510 of file lwip_tcp.c.

void tcp_debug_print_flags ( u8_t flags )

Print tcp flags for debugging purposes.

Parameters:

flags tcp flags, all active flags are printed

Definition at line 1557 of file lwip_tcp.c.

void tcp_debug_print_pcbs ( void )

Print all tcp_pcbs in every list for debugging purposes.

Definition at line 1590 of file lwip_tcp.c.

void tcp_debug_print_state ( enum tcp_state s )

Print a tcp state for debugging purposes.

Parameters:

s	enum tcp_state to print

Definition at line 1546 of file lwip_tcp.c.

u16_t tcp_eff_send_mss	(	u16_t	sendmss,
		ip_addr_t *	addr
	)

Calcluates the effective send mss that can be used for a specific IP address by using ip_route to determin the netif used to send to the address and calculating the minimum of TCP_MSS and that netif's mtu (if set).

Definition at line 1479 of file lwip_tcp.c.

void tcp_err	(	struct tcp_pcb *	pcb,
		tcp_err_fn	err
	)

Used to specify the function that should be called when a fatal error has occured on the connection.

Parameters:

pcb	tcp_pcb to set the err callback
err	callback function to call for this pcb when a fatal error has occured on the connection

Definition at line 1318 of file lwip_tcp.c.

void tcp_fasttmr ( void )

Is called every TCP_FAST_INTERVAL (250 ms) and process data previously "refused" by upper layer (application) and sends delayed ACKs.

Automatically called from tcp_tmr().

Definition at line 993 of file lwip_tcp.c.

static void tcp_kill_prio ( u8_t prio ) [static]

Kills the oldest active connection that has lower priority than prio.

Parameters:

prio	minimum priority

Definition at line 1119 of file lwip_tcp.c.

static void tcp_kill_timewait ( void ) [static]

Kills the oldest connection that is in TIME_WAIT state.

Called from tcp_alloc() if no more connections are available.

Definition at line 1152 of file lwip_tcp.c.

struct tcp_pcb* tcp_listen_with_backlog	(	struct tcp_pcb *	pcb,
		u8_t	backlog
	)		`[read]`

Set the state of the connection to be LISTEN, which means that it is able to accept incoming connections.

The protocol control block is reallocated in order to consume less memory. Setting the connection to LISTEN is an irreversible process.

Parameters:

pcb	the original tcp_pcb
backlog	the incoming connections queue limit

Returns:: tcp_pcb used for listening, consumes less memory.

Note:: The original tcp_pcb is freed. This function therefore has to be called like this: tpcb = tcp_listen(tpcb);

Definition at line 483 of file lwip_tcp.c.

struct tcp_pcb* tcp_new ( void ) [read]

Creates a new TCP protocol control block but doesn't place it on any of the TCP PCB lists.

The pcb is not put on any list until binding using tcp_bind().

Definition at line 1264 of file lwip_tcp.c.

static u16_t tcp_new_port ( void ) [static]

A nastly hack featuring 'goto' statements that allocates a new TCP local port.

Returns:: a new (free) local TCP port number

Definition at line 609 of file lwip_tcp.c.

u32_t tcp_next_iss ( void )

Calculates a new initial sequence number for new connections.

Returns:: u32_t pseudo random sequence number

Definition at line 1464 of file lwip_tcp.c.

void tcp_pcb_purge ( struct tcp_pcb * pcb )

Purges a TCP PCB.

Removes any buffered data and frees the buffer memory (pcb->ooseq, pcb->unsent and pcb->unacked are freed).

Parameters:

pcb	tcp_pcb to purge. The pcb itself is not deallocated!

Definition at line 1363 of file lwip_tcp.c.

void tcp_pcb_remove	(	struct tcp_pcb **	pcblist,
		struct tcp_pcb *	pcb
	)

Purges the PCB and removes it from a PCB list.

Any delayed ACKs are sent first.

Parameters:

pcblist	PCB list to purge.
pcb	tcp_pcb to purge. The pcb itself is NOT deallocated!

Definition at line 1431 of file lwip_tcp.c.

s16_t tcp_pcbs_sane ( void )

Check state consistency of the tcp_pcb lists.

Definition at line 1620 of file lwip_tcp.c.

void tcp_poll	(	struct tcp_pcb *	pcb,
		tcp_poll_fn	poll,
		u8_t	interval
	)

Used to specify the function that should be called periodically from TCP.

The interval is specified in terms of the TCP coarse timer interval, which is called twice a second.

Definition at line 1346 of file lwip_tcp.c.

void tcp_recv	(	struct tcp_pcb *	pcb,
		tcp_recv_fn	recv
	)

Used to specify the function that should be called when a TCP connection receives data.

Parameters:

pcb	tcp_pcb to set the recv callback
recv	callback function to call for this pcb when data is received

Definition at line 1291 of file lwip_tcp.c.

err_t tcp_recv_null	(	void *	arg,
		struct tcp_pcb *	pcb,
		struct pbuf *	p,
		err_t	err
	)

Default receive callback that is called if the user didn't register a recv callback for the pcb.

Definition at line 1100 of file lwip_tcp.c.

void tcp_recved	(	struct tcp_pcb *	pcb,
		u16_t	len
	)

This function should be called by the application when it has processed the data.

The purpose is to advertise a larger window when the data has been processed.

Parameters:

pcb	the tcp_pcb for which data is read
len	the amount of bytes that have been read by the application

Definition at line 575 of file lwip_tcp.c.

struct tcp_seg* tcp_seg_copy ( struct tcp_seg * seg ) [read]

Returns a copy of the given TCP segment.

The pbuf and data are not copied, only the pointers

Parameters:

seg	the old tcp_seg

Returns:: a copy of seg

Definition at line 1080 of file lwip_tcp.c.

void tcp_seg_free ( struct tcp_seg * seg )

Frees a TCP segment (tcp_seg structure).

Parameters:

seg	single tcp_seg to free

Definition at line 1046 of file lwip_tcp.c.

void tcp_segs_free ( struct tcp_seg * seg )

Deallocates a list of TCP segments (tcp_seg structures).

Parameters:

seg	tcp_seg list of TCP segments to free

Definition at line 1031 of file lwip_tcp.c.

void tcp_sent	(	struct tcp_pcb *	pcb,
		tcp_sent_fn	sent
	)

Used to specify the function that should be called when TCP data has been successfully delivered to the remote host.

Parameters:

pcb	tcp_pcb to set the sent callback
sent	callback function to call for this pcb when data is successfully sent

Definition at line 1304 of file lwip_tcp.c.

void tcp_setprio	(	struct tcp_pcb *	pcb,
		u8_t	prio
	)

Sets the priority of a connection.

Parameters:

pcb	the tcp_pcb to manipulate
prio	new priority

Definition at line 1066 of file lwip_tcp.c.

err_t tcp_shutdown	(	struct tcp_pcb *	pcb,
		int	shut_rx,
		int	shut_tx
	)

Causes all or part of a full-duplex connection of this PCB to be shut down.

This doesn't deallocate the PCB!

Parameters:

pcb	PCB to shutdown
shut_rx	shut down receive side if this is != 0
shut_tx	shut down send side if this is != 0

Returns:: ERR_OK if shutdown succeeded (or the PCB has already been shut down) another err_t on error.

Definition at line 278 of file lwip_tcp.c.

void tcp_slowtmr ( void )

Called every 500 ms and implements the retransmission timer and the timer that removes PCBs that have been in TIME-WAIT for enough time.

It also increments various timers such as the inactivity timer in each PCB.

Automatically called from tcp_tmr().

Definition at line 750 of file lwip_tcp.c.

void tcp_tmr ( void )

Called periodically to dispatch TCP timers.

Definition at line 109 of file lwip_tcp.c.

u32_t tcp_update_rcv_ann_wnd ( struct tcp_pcb * pcb )

Update the state that tracks the available window space to advertise.

Returns how much extra window would be advertised if we sent an update now.

Definition at line 543 of file lwip_tcp.c.

Variable Documentation

struct tcp_pcb* tcp_active_pcbs

List of all TCP PCBs that are in a state in which they accept or send data.

Definition at line 87 of file lwip_tcp.c.

struct tcp_pcb* tcp_bound_pcbs

List of all TCP PCBs bound but not yet (connected || listening)

Definition at line 82 of file lwip_tcp.c.

union tcp_listen_pcbs_t tcp_listen_pcbs

List of all TCP PCBs in LISTEN state.

Definition at line 84 of file lwip_tcp.c.

struct tcp_pcb** const tcp_pcb_lists[]

Initial value:

 {&tcp_listen_pcbs.pcbs, &tcp_bound_pcbs,
  &tcp_active_pcbs, &tcp_tw_pcbs}

An array with all (non-temporary) PCB lists, mainly used for smaller code size.

Definition at line 94 of file lwip_tcp.c.

u8_t tcp_timer [static]

Timer counter to handle calling slow-timer from tcp_tmr()

Definition at line 101 of file lwip_tcp.c.

struct tcp_pcb* tcp_tmp_pcb

Only used for temporary storage.

Definition at line 98 of file lwip_tcp.c.

struct tcp_pcb* tcp_tw_pcbs

List of all TCP PCBs in TIME-WAIT state.

Definition at line 89 of file lwip_tcp.c.

Type:	Program
Created:	22 Oct 2016
Imports:	1
Forks:	1
Commits:	10
Dependents:	0
Dependencies:	3
Followers:	1

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