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TCP(3X) TCP(3X) NAME tcp_sock, tcp_connect, tcp_listen, tcp_accept, tcp_rcmd - tcp network- ing functions SYNOPSIS #include <sys/inet/tcp_user.h> int tcp_sock(); int tcp_connect(fd, tp) int fd; struct tcpuser *tp; int tcp_listen(fd, tp) int fd; struct tcpuser *tp; int tcp_accept(fd, tp) int fd; struct tcpuser *tp; int tcp_rcmd(host, port, locuser, remuser, cmd, fd2p) char *host, *port, *locuser, *remuser, *cmd; int *fd2p; DESCRIPTION These routines are loaded by the -lin option of ld(1). TCP is a protocol layered upon IP (internet protocol). It provides full-duplex byte stream connections between end points called sockets. The address of a socket is composed of the internet address of its host and the port number to which the socket is bound. Tcp_sock returns the file descriptor of an unbound socket. Once opened, a socket may be bound to a port number within the host and set up as the active or passive end of a connection. Addresses and parameters are passed in tcpuser structures: struct tcpuser { int code; tcp_port lport, fport; in_addr laddr, faddr; int param; }; Lport and laddr refer to the port and address numbers of the local end of a connection. Fport and faddr refer to the port and address numbers of the foreign end of a connection. Tcp_connect binds socket fd to port tp->lport and attempts to set up a connection to the socket bound to port tp->fport on host tp->faddr. If tp->lport is 0, a local port number is automatically chosen. Tcp_con- nect returns 0 if the connection is established, -1 otherwise. Tp->lport and tp->laddr are filled in to reflect the local port and ad- dress numbers for the connection. Communication proceeds by performing read(2) and write on fd. If tp->param is non-zero, it specifies op- tions to set for the connection. The only option supported is SO_KEEPALIVE which causes empty messages to be sent periodically to de- tect dead connections. Tcp_listen binds socket fd to port tp->lport and configures the socket to listen for connection requests to that port. If tp->faddr and tp->fport are non-zero, only connections coming from sockets on machine faddr and bound to port fport are listened for. Tcp_listen returns 0 on success, -1 otherwise. tp->laddr is filled in to reflect the local address number for the connection. Select(2) can be used with a lis- tening socket to provide asynchronous polling of connection requests by selecting for pending input on the socket. Tcp_accept waits for and accepts a connection request sent to the lis- tening socket fd. When a connection arrives, tcp_accept returns a new file descriptor over which communications can proceed. Tp->faddr, tp->fport, tp->laddr, and tp->lport are filled in to identify the two ends of the connection. Tp->param is filled in with the minor device number of the tcp device used for the new connection. Fd is left open and continues listening for connections. Tcp_rcmd remotely executes a cmd on host as user remuser. Standard in- put is attached to cmd's standard input and cmd's standard output is attached to standard output. If fd2p is non-zero, it is filled with the file descriptor of a new TCP connection attached to cmd's standard error. Otherwise, cmd's standard error is attached to its standard output. FILES the socket devices SEE ALSO ipc(3), internet(3), udp(3) DIAGNOSTICS Tcp_sock returns -1 if no sockets are available. TCP(3X)