tcpout.c File Reference

TCP output functions. More...

#include <cfg/os.h>
#include <string.h>
#include <errno.h>
#include <sys/heap.h>
#include <sys/event.h>
#include <sys/timer.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/icmp.h>
#include <netinet/ip_icmp.h>
#include <netinet/ipcsum.h>
#include <sys/socket.h>
#include <netinet/tcp.h>
#include <sys/thread.h>
#include <net/netdebug.h>

Include dependency graph for tcpout.c:

Functions
int	NutTcpOutput (TCPSOCKET *sock, const uint8_t *data, uint16_t size)
	Initiate TCP segment transmission.
int	NutTcpReject (NETBUF *nb)
	Reject an incoming segment.

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Detailed Description

TCP output functions.

 * $Id: tcpout.c 4473 2012-08-20 15:12:45Z haraldkipp $
 * 

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Function Documentation

int NutTcpOutput	(	TCPSOCKET *	sock,
		const uint8_t *	data,
		uint16_t	size
	)

Initiate TCP segment transmission.

Check the TCP socket status and send any segment waiting for transmission.

The function will not return until the data has been stored in the network device hardware for transmission. If the device is not ready for transmitting a new packet, the calling thread will be suspended until the device becomes ready again.

If the target host is connected through an Ethernet network and if the hardware address of that host is currently unknown, an ARP request is sent out and the function will block until a response is received or an ARP timeout occurs.

Segments containing data or SYN and FIN flags are added to a special queue for unacknowledged segments and will be retransmitted by the TCP timer thread, if not acknowledged by the remote within a specific time. The state machine will remove these segments from the queue as soon as they are acknowledged.

Note:

This function is mainly used by the TCP state machine. Applications typically do not call this function but use NutTcpSend(), which is part of the TCP socket interface.

Parameters:

sock	Socket descriptor. This pointer must have been retrieved by calling NutTcpCreateSocket().
data	Pointer to TCP segment contents.
size	TCP segment length.

Returns:

0 on success, -1 otherwise. Returning 0 does not imply that the data has been successfully delivered, because flow control and retransmission is still handled in the background.

References __tcp_trf, __tcp_trs, ENOBUFS, htonl, htons, IPPROTO_TCP, memcpy(), _NETBUF::nb_ap, _NETBUF::nb_next, _NETBUF::nb_tp, NBAF_APPLICATION, NBAF_TRANSPORT, ntohl, NULL, NutDumpTcpHeader(), NutGetMillis(), NutIpChkSum(), NutIpChkSumPartial(), NutIpOutput(), NutIpPseudoChkSumPartial(), NutNetBufAlloc(), NutNetBufClonePart(), NutNetBufFree(), SO_ACK, SO_FIN, SO_FORCE, tcp_socket::so_last_error, tcp_socket::so_local_addr, tcp_socket::so_local_port, tcp_socket::so_mss, tcp_socket::so_remote_addr, tcp_socket::so_remote_port, tcp_socket::so_retran_time, tcp_socket::so_rtt_seq, tcp_socket::so_rx_nxt, tcp_socket::so_rx_win, SO_SYN, tcp_socket::so_tx_flags, tcp_socket::so_tx_nbq, tcp_socket::so_tx_nxt, _NBDATA::sz, TCPOLEN_MAXSEG, TCPOPT_MAXSEG, TH_ACK, tcphdr::th_ack, tcphdr::th_dport, TH_FIN, tcphdr::th_flags, tcphdr::th_off, TH_PUSH, tcphdr::th_seq, tcphdr::th_sport, tcphdr::th_sum, TH_SYN, tcphdr::th_urp, tcphdr::th_win, tcphdr::th_x2, and _NBDATA::vp.

Referenced by NutTcpSend(), NutTcpSm(), and NutTcpStateWindowEvent().

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int NutTcpReject

(

NETBUF *

nb

)

Reject an incoming segment.

Send RST in response to an incoming segment, which should be rejected.

The function avoids to send out a RST segment in response to an incoming RST segment.

Note:

This function is mainly used by the TCP state machine. Applications typically do not call this function.

Parameters:

nb	Network buffer structure of the incoming segment. Will be released within this function.

Returns:

0 on success, -1 otherwise.

References __tcp_trf, __tcp_trs, htonl, htons, ip::ip_dst, ip::ip_src, IPPROTO_TCP, _NETBUF::nb_ap, _NETBUF::nb_nw, _NETBUF::nb_tp, ntohl, NutDumpTcpHeader(), NutIpChkSum(), NutIpOutput(), NutIpPseudoChkSumPartial(), NutNetBufFree(), _NBDATA::sz, TH_ACK, TH_RST, TH_SYN, and _NBDATA::vp.

Referenced by NutTcpSm(), and NutTcpStateMachine().

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