Transmission Control Protocol for IP
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Functions
void	tcp_backlog_delayed (struct tcp_pcb *pcb)
	Delay accepting a connection in respect to the listen backlog: the number of outstanding connections is increased until tcp_backlog_accepted() is called.
void	tcp_backlog_accepted (struct tcp_pcb *pcb)
	A delayed-accept a connection is accepted (or closed/aborted): decreases the number of outstanding connections after calling tcp_backlog_delayed().
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_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, const ip_addr_t ipaddr, u16_t port)
	Binds the connection to a local port number and IP address.
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.
struct tcp_pcb *	tcp_listen_with_backlog_and_err (struct tcp_pcb pcb, u8_t backlog, err_t err)
	Set the state of the connection to be LISTEN, which means that it is able to accept incoming connections.
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, const ip_addr_t ipaddr, u16_t port, tcp_connected_fn connected)
	Connects to another host.
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.
struct tcp_pcb *	tcp_new_ip_type (u8_t type)
	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 occurred 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.
err_t	tcp_write (struct tcp_pcb pcb, const void arg, u16_t len, u8_t apiflags)
	Write data for sending (but does not send it immediately).
err_t	tcp_output (struct tcp_pcb *pcb)
	Find out what we can send and send it.

Detailed Description

Transmission Control Protocol for IP
.

See also:: lwIP API and Netconn API

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.

Function Documentation

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 535 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 1769 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 1695 of file lwip_tcp.c.

void tcp_backlog_accepted ( struct tcp_pcb * pcb )

A delayed-accept a connection is accepted (or closed/aborted): decreases the number of outstanding connections after calling tcp_backlog_delayed().

ATTENTION: the caller is responsible for calling tcp_backlog_accepted() or else the backlog feature will get out of sync!

Parameters:

pcb	the connection pcb which is now fully accepted (or closed/aborted)

Definition at line 235 of file lwip_tcp.c.

void tcp_backlog_delayed ( struct tcp_pcb * pcb )

Delay accepting a connection in respect to the listen backlog: the number of outstanding connections is increased until tcp_backlog_accepted() is called.

ATTENTION: the caller is responsible for calling tcp_backlog_accepted() or else the backlog feature will get out of sync!

Parameters:

pcb	the connection pcb which is not fully accepted yet

Definition at line 213 of file lwip_tcp.c.

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

Binds the connection to a local port number 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 IP4_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 556 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 393 of file lwip_tcp.c.

err_t tcp_connect	(	struct tcp_pcb *	pcb,
		const 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 (on error, the err calback will be called)

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 871 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 occurred on the connection.

Note:: The corresponding pcb is already freed when this callback is called!

Parameters:

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

Definition at line 1751 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_with_backlog(tpcb, backlog);

Definition at line 658 of file lwip_tcp.c.

struct tcp_pcb* tcp_listen_with_backlog_and_err	(	struct tcp_pcb *	pcb,
		u8_t	backlog,
		err_t *	err
	)		`[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
err	when NULL is returned, this contains the error reason

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_with_backlog_and_err(tpcb, backlog, &err);

Definition at line 680 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 1654 of file lwip_tcp.c.

struct tcp_pcb* tcp_new_ip_type ( u8_t type ) [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().

Parameters:

type	IP address type, see lwip_ip_addr_type definitions. If you want to listen to IPv4 and IPv6 (dual-stack) connections, supply IPADDR_TYPE_ANY as argument and bind to IP_ANY_TYPE.

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

Definition at line 1671 of file lwip_tcp.c.

err_t tcp_output ( struct tcp_pcb * pcb )

Find out what we can send and send it.

Parameters:

pcb	Protocol control block for the TCP connection to send data

Returns:: ERR_OK if data has been sent or nothing to send another err_t on error

Definition at line 993 of file lwip_tcp_out.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 1787 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 1714 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 788 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 1731 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 unless shutting down both sides! Shutting down both sides is the same as calling tcp_close, so if it succeds, the PCB should not be referenced any more.

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 420 of file lwip_tcp.c.

err_t tcp_write	(	struct tcp_pcb *	pcb,
		const void *	arg,
		u16_t	len,
		u8_t	apiflags
	)

Write data for sending (but does not send it immediately).

It waits in the expectation of more data being sent soon (as it can send them more efficiently by combining them together). To prompt the system to send data now, call tcp_output() after calling tcp_write().

Parameters:

pcb	Protocol control block for the TCP connection to enqueue data for.
arg	Pointer to the data to be enqueued for sending.
len	Data length in bytes
apiflags	combination of following flags : TCP_WRITE_FLAG_COPY (0x01) data will be copied into memory belonging to the stack TCP_WRITE_FLAG_MORE (0x02) for TCP connection, PSH flag will not be set on last segment sent,

Returns:: ERR_OK if enqueued, another err_t on error

Definition at line 368 of file lwip_tcp_out.c.

Type:	Program
Mbed OS support:	Mbed OS
Created:	23 Feb 2019
Imports:	43
Forks:	0
Commits:	1
Dependents:	0
Dependencies:	0
Followers:	1

TCP
[Callback-style APIs]

Functions

Detailed Description

Function Documentation

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TCP [Callback-style APIs]

Functions

Detailed Description

Function Documentation

Repository toolbox

Repository details

Important Information for this Arm website

Access Warning

TCP
[Callback-style APIs]