Transmission Control Protocol, outgoing traffic. More...

Functions
static err_t	tcp_output_segment (struct tcp_seg seg, struct tcp_pcb pcb, struct netif *netif)
	Called by tcp_output() to actually send a TCP segment over IP.
static struct pbuf *	tcp_output_alloc_header (struct tcp_pcb *pcb, u16_t optlen, u16_t datalen, u32_t seqno_be)
	Allocate a pbuf and create a tcphdr at p->payload, used for output functions other than the default tcp_output -> tcp_output_segment (e.g.
err_t	tcp_send_fin (struct tcp_pcb *pcb)
	Called by tcp_close() to send a segment including FIN flag but not data.
static struct tcp_seg *	tcp_create_segment (struct tcp_pcb pcb, struct pbuf p, u8_t flags, u32_t seqno, u8_t optflags)
	Create a TCP segment with prefilled header.
static struct pbuf *	tcp_pbuf_prealloc (pbuf_layer layer, u16_t length, u16_t max_length, u16_t oversize, struct tcp_pcb pcb, u8_t apiflags, u8_t first_seg)
	Allocate a PBUF_RAM pbuf, perhaps with extra space at the end.
static void	tcp_seg_add_chksum (u16_t chksum, u16_t len, u16_t seg_chksum, u8_t seg_chksum_swapped)
	Add a checksum of newly added data to the segment.
static err_t	tcp_write_checks (struct tcp_pcb *pcb, u16_t len)
	Checks if tcp_write is allowed or not (checks state, snd_buf and snd_queuelen).
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_enqueue_flags (struct tcp_pcb *pcb, u8_t flags)
	Enqueue TCP options for transmission.
static void	tcp_build_wnd_scale_option (u32_t *opts)
	Build a window scale option (3 bytes long) at the specified options pointer)
err_t	tcp_send_empty_ack (struct tcp_pcb *pcb)
	Send an ACK without data.
err_t	tcp_output (struct tcp_pcb *pcb)
	Find out what we can send and send it.
void	tcp_rst (u32_t seqno, u32_t ackno, const ip_addr_t local_ip, const ip_addr_t remote_ip, u16_t local_port, u16_t remote_port)
	Send a TCP RESET packet (empty segment with RST flag set) either to abort a connection or to show that there is no matching local connection for a received segment.
void	tcp_rexmit_rto (struct tcp_pcb *pcb)
	Requeue all unacked segments for retransmission.
void	tcp_rexmit (struct tcp_pcb *pcb)
	Requeue the first unacked segment for retransmission.
void	tcp_rexmit_fast (struct tcp_pcb *pcb)
	Handle retransmission after three dupacks received.
err_t	tcp_keepalive (struct tcp_pcb *pcb)
	Send keepalive packets to keep a connection active although no data is sent over it.
err_t	tcp_zero_window_probe (struct tcp_pcb *pcb)
	Send persist timer zero-window probes to keep a connection active when a window update is lost.

Detailed Description

Transmission Control Protocol, outgoing traffic.

The output functions of TCP.

Definition in file lwip_tcp_out.c.

Function Documentation

static void tcp_build_wnd_scale_option ( u32_t * opts ) [static]

Build a window scale option (3 bytes long) at the specified options pointer)

Parameters:

opts	option pointer where to store the window scale option

Definition at line 905 of file lwip_tcp_out.c.

static struct tcp_seg* tcp_create_segment	(	struct tcp_pcb *	pcb,
		struct pbuf *	p,
		u8_t	flags,
		u32_t	seqno,
		u8_t	optflags
	)		`[static, read]`

Create a TCP segment with prefilled header.

Called by tcp_write and tcp_enqueue_flags.

Parameters:

pcb	Protocol control block for the TCP connection.
p	pbuf that is used to hold the TCP header.
flags	TCP flags for header.
seqno	TCP sequence number of this packet
optflags	options to include in TCP header

Returns:: a new tcp_seg pointing to p, or NULL. The TCP header is filled in except ackno and wnd. p is freed on failure.

Definition at line 173 of file lwip_tcp_out.c.

err_t tcp_enqueue_flags	(	struct tcp_pcb *	pcb,
		u8_t	flags
	)

Enqueue TCP options for transmission.

Called by tcp_connect(), tcp_listen_input(), and tcp_send_ctrl().

Parameters:

pcb	Protocol control block for the TCP connection.
flags	TCP header flags to set in the outgoing segment.

Definition at line 785 of file lwip_tcp_out.c.

err_t tcp_keepalive ( struct tcp_pcb * pcb )

Send keepalive packets to keep a connection active although no data is sent over it.

Called by tcp_slowtmr()

Parameters:

pcb	the tcp_pcb for which to send a keepalive packet

Definition at line 1532 of file lwip_tcp_out.c.

static struct pbuf* tcp_output_alloc_header	(	struct tcp_pcb *	pcb,
		u16_t	optlen,
		u16_t	datalen,
		u32_t	seqno_be
	)		`[static, read]`

Allocate a pbuf and create a tcphdr at p->payload, used for output functions other than the default tcp_output -> tcp_output_segment (e.g.

tcp_send_empty_ack, etc.)

Parameters:

pcb	tcp pcb for which to send a packet (used to initialize tcp_hdr)
optlen	length of header-options
datalen	length of tcp data to reserve in pbuf
seqno_be	seqno in network byte order (big-endian)

Returns:: pbuf with p->payload being the tcp_hdr

Definition at line 108 of file lwip_tcp_out.c.

static err_t tcp_output_segment	(	struct tcp_seg *	seg,
		struct tcp_pcb *	pcb,
		struct netif *	netif
	)		`[static]`

Called by tcp_output() to actually send a TCP segment over IP.

Parameters:

seg	the tcp_seg to send
pcb	the tcp_pcb for the TCP connection used to send the segment
netif	the netif used to send the segment

Exclude retransmitted segments from this count.

Definition at line 1189 of file lwip_tcp_out.c.

static struct pbuf* tcp_pbuf_prealloc	(	pbuf_layer	layer,
		u16_t	length,
		u16_t	max_length,
		u16_t *	oversize,
		struct tcp_pcb *	pcb,
		u8_t	apiflags,
		u8_t	first_seg
	)		`[static, read]`

Allocate a PBUF_RAM pbuf, perhaps with extra space at the end.

This function is like pbuf_alloc(layer, length, PBUF_RAM) except there may be extra bytes available at the end.

Parameters:

layer	flag to define header size.
length	size of the pbuf's payload.
max_length	maximum usable size of payload+oversize.
oversize	pointer to a u16_t that will receive the number of usable tail bytes.
pcb	The TCP connection that will enqueue the pbuf.
apiflags	API flags given to tcp_write.
first_seg	true when this pbuf will be used in the first enqueued segment.

Definition at line 233 of file lwip_tcp_out.c.

void tcp_rexmit ( struct tcp_pcb * pcb )

Requeue the first unacked segment for retransmission.

Called by tcp_receive() for fast retransmit.

Parameters:

pcb	the tcp_pcb for which to retransmit the first unacked segment

Definition at line 1442 of file lwip_tcp_out.c.

void tcp_rexmit_fast ( struct tcp_pcb * pcb )

Handle retransmission after three dupacks received.

Parameters:

pcb	the tcp_pcb for which to retransmit the first unacked segment

Definition at line 1490 of file lwip_tcp_out.c.

void tcp_rexmit_rto ( struct tcp_pcb * pcb )

Requeue all unacked segments for retransmission.

Called by tcp_slowtmr() for slow retransmission.

Parameters:

pcb	the tcp_pcb for which to re-enqueue all unacked segments

Definition at line 1399 of file lwip_tcp_out.c.

void tcp_rst	(	u32_t	seqno,
		u32_t	ackno,
		const ip_addr_t *	local_ip,
		const ip_addr_t *	remote_ip,
		u16_t	local_port,
		u16_t	remote_port
	)

Send a TCP RESET packet (empty segment with RST flag set) either to abort a connection or to show that there is no matching local connection for a received segment.

Called by tcp_abort() (to abort a local connection), tcp_input() (if no matching local pcb was found), tcp_listen_input() (if incoming segment has ACK flag set) and tcp_process() (received segment in the wrong state)

Since a RST segment is in most cases not sent for an active connection, tcp_rst() has a number of arguments that are taken from a tcp_pcb for most other segment output functions.

Parameters:

seqno	the sequence number to use for the outgoing segment
ackno	the acknowledge number to use for the outgoing segment
local_ip	the local IP address to send the segment from
remote_ip	the remote IP address to send the segment to
local_port	the local TCP port to send the segment from
remote_port	the remote TCP port to send the segment to

Definition at line 1344 of file lwip_tcp_out.c.

static void tcp_seg_add_chksum	(	u16_t	chksum,
		u16_t	len,
		u16_t *	seg_chksum,
		u8_t *	seg_chksum_swapped
	)		`[static]`

Add a checksum of newly added data to the segment.

Definition at line 285 of file lwip_tcp_out.c.

err_t tcp_send_empty_ack ( struct tcp_pcb * pcb )

Send an ACK without data.

Parameters:

pcb	Protocol control block for the TCP connection to send the ACK

Definition at line 918 of file lwip_tcp_out.c.

err_t tcp_send_fin ( struct tcp_pcb * pcb )

Called by tcp_close() to send a segment including FIN flag but not data.

Parameters:

pcb	the tcp_pcb over which to send a segment

Returns:: ERR_OK if sent, another err_t otherwise

Definition at line 139 of file lwip_tcp_out.c.

static err_t tcp_write_checks	(	struct tcp_pcb *	pcb,
		u16_t	len
	)		`[static]`

Checks if tcp_write is allowed or not (checks state, snd_buf and snd_queuelen).

Parameters:

pcb	the tcp pcb to check for
len	length of data to send (checked agains snd_buf)

Returns:: ERR_OK if tcp_write is allowed to proceed, another err_t otherwise

Definition at line 307 of file lwip_tcp_out.c.

err_t tcp_zero_window_probe ( struct tcp_pcb * pcb )

Send persist timer zero-window probes to keep a connection active when a window update is lost.

Called by tcp_slowtmr()

Parameters:

pcb	the tcp_pcb for which to send a zero-window probe packet

Definition at line 1586 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

lwip_tcp_out.c File Reference

Functions

Detailed Description

Function Documentation

Repository toolbox

Repository details

Important Information for this Arm website

lwip_tcp_out.c File Reference

Functions

Detailed Description

Function Documentation

Repository toolbox

Repository details

Important Information for this Arm website

Access Warning