TCP
[Base Protocols]

Collaboration diagram for TCP:

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Detailed Description

RFC 793 Transmission Control Protocol.

TCP provides reliable, in-sequence delivery of a full-duplex stream of octets. It is used by applications which need a reliable, connection-oriented data transport.

Applications should call the TCP Socket API when using this protocol.

Todo:

Use an indirect call for NutTcpInput(). Right now, the whole TCP code is linked to any application, even if only UDP is used.

Defines
#define	min(a, b)   ((a>b)?b:a)
#define	max(a, b)   ((a>b)?a:b)
Functions
void	NutTcpInput (NETBUF *nb)
	Process incoming TCP segments from IP layer.
int	NutTcpStatePassiveOpenEvent (TCPSOCKET *sock)
	Initiated by the application.
int	NutTcpStateActiveOpenEvent (TCPSOCKET *sock)
	Initiated by the application.
int	NutTcpStateCloseEvent (TCPSOCKET *sock)
	Socket close by application.
int	NutTcpStateWindowEvent (TCPSOCKET *sock)
	Initiated by the application.
int	NutTcpStateRetranTimeout (TCPSOCKET *sock)
	Retransmit a segment after ACK timeout.
void	NutTcpSm (void *arg)
	TCP state machine thread.
void	NutTcpStateMachine (NETBUF *nb)
	Process incoming TCP segments.
int	NutTcpInitStateMachine (void)
	Start TCP state machine.
int	NutTcpAbortSocket (TCPSOCKET *sock, u_short last_error)
	Closes socket with error.
int	IsInLimits (u_long x, u_long low, u_long high)
	Sequence number comparisons.
void	NutTcpCalcRtt (TCPSOCKET *sock)
Variables
HANDLE	tcp_in_rdy
NETBUF *volatile	tcp_in_nbq

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Function Documentation

void NutTcpInput (  NETBUF *  nb  )

Process incoming TCP segments from IP layer. Warning: The caller must take care not to pass broadcast or multicast segments. Note: This routine is called by the IP layer on incoming TCP segments. Applications typically do not call this function.

int NutTcpStatePassiveOpenEvent (  TCPSOCKET *  sock  )

Initiated by the application. Parameters: sock  Socket descriptor. This pointer must have been retrieved by calling NutTcpCreateSocket(). Returns: 0 if granted, error code otherwise.

int NutTcpStateActiveOpenEvent (  TCPSOCKET *  sock  )

Initiated by the application. The caller must make sure, that the socket is in closed state. Parameters: sock  Socket descriptor. This pointer must have been retrieved by calling NutTcpCreateSocket(). Returns: 0 if granted, -1 otherwise.

int NutTcpStateCloseEvent (  TCPSOCKET *  sock  )

Socket close by application. If socket is in state SYN_RECEIVED or ESTABLISHED, it is changed to FINWAIT1. No further data sending is accepted. Receiving is still allowed. Parameters: sock  Socket descriptor. This pointer must have been retrieved by calling NutTcpCreateSocket().

int NutTcpStateWindowEvent (  TCPSOCKET *  sock  )

Initiated by the application. Parameters: sock  Socket descriptor. This pointer must have been retrieved by calling NutTcpCreateSocket().

int NutTcpStateRetranTimeout (  TCPSOCKET *  sock  )

Retransmit a segment after ACK timeout. This function is called by the TCP timer. Parameters: sock  Socket descriptor. This pointer must have been retrieved by calling NutTcpCreateSocket(). Returns: Nonzero if socket was aborted due to reach of retransmit limit or network error.

NutTcpSm (  void *  arg  )

TCP state machine thread. The TCP state machine serves two purposes: It processes incoming TCP segments and handles TCP timers.

void NutTcpStateMachine (  NETBUF *  nb  )

Process incoming TCP segments. All incoming TCP packets are passed to this routine. They will be added to a global queue and processed by the TCP state machine, which is running on a separate thread. Note: This routine is called by the IP layer on incoming TCP segments. Applications typically do not call this function.

int NutTcpInitStateMachine (  void   )

Start TCP state machine. The socket interface will automatically call this routine as soon as the first socket is created. Returns: 0 on success, -1 otherwise.

int NutTcpAbortSocket (  TCPSOCKET *  sock, u_short  last_error )

Closes socket with error. Aborts any socket activity and sets last error. Parameters: sock  Socket descriptor. last_error  Error number to report Note: This routine is called internally by Nut/Net. Applications typically do not call this function. Returns: 0 on success, -1 otherwise.

int IsInLimits (  u_long  x, u_long  low, u_long  high )

Sequence number comparisons. Return true if x is between low and high inclusive, false otherwise

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