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Annotation of 43BSDReno/share/man/man4/tcp.4, revision 1.1

1.1     ! root        1: .\" Copyright (c) 1983 The Regents of the University of California.
        !             2: .\" All rights reserved.
        !             3: .\"
        !             4: .\" Redistribution and use in source and binary forms are permitted provided
        !             5: .\" that: (1) source distributions retain this entire copyright notice and
        !             6: .\" comment, and (2) distributions including binaries display the following
        !             7: .\" acknowledgement:  ``This product includes software developed by the
        !             8: .\" University of California, Berkeley and its contributors'' in the
        !             9: .\" documentation or other materials provided with the distribution and in
        !            10: .\" all advertising materials mentioning features or use of this software.
        !            11: .\" Neither the name of the University nor the names of its contributors may
        !            12: .\" be used to endorse or promote products derived from this software without
        !            13: .\" specific prior written permission.
        !            14: .\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
        !            15: .\" WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
        !            16: .\" MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
        !            17: .\"
        !            18: .\"    @(#)tcp.4       6.4 (Berkeley) 6/23/90
        !            19: .\"
        !            20: .TH TCP 4 "June 23, 1990"
        !            21: .UC 5
        !            22: .SH NAME
        !            23: tcp \- Internet Transmission Control Protocol
        !            24: .SH SYNOPSIS
        !            25: .B #include <sys/socket.h>
        !            26: .br
        !            27: .B #include <netinet/in.h>
        !            28: .PP
        !            29: .B s = socket(AF_INET, SOCK_STREAM, 0);
        !            30: .SH DESCRIPTION
        !            31: The TCP protocol provides reliable, flow-controlled, two-way
        !            32: transmission of data.  It is a byte-stream protocol used to
        !            33: support the SOCK_STREAM abstraction.  TCP uses the standard
        !            34: Internet address format and, in addition, provides a per-host
        !            35: collection of \*(lqport addresses\*(rq.  Thus, each address is composed
        !            36: of an Internet address specifying the host and network, with
        !            37: a specific TCP port on the host identifying the peer entity.
        !            38: .PP
        !            39: Sockets utilizing the tcp protocol are either \*(lqactive\*(rq or
        !            40: \*(lqpassive\*(rq.  Active sockets initiate connections to passive
        !            41: sockets.  By default TCP sockets are created active; to create a
        !            42: passive socket the
        !            43: .IR listen (2)
        !            44: system call must be used
        !            45: after binding the socket with the
        !            46: .IR bind (2)
        !            47: system call.  Only
        !            48: passive sockets may use the 
        !            49: .IR accept (2)
        !            50: call to accept incoming connections.  Only active sockets may
        !            51: use the
        !            52: .IR connect (2)
        !            53: call to initiate connections.
        !            54: .PP
        !            55: Passive sockets may \*(lqunderspecify\*(rq their location to match
        !            56: incoming connection requests from multiple networks.  This
        !            57: technique, termed \*(lqwildcard addressing\*(rq, allows a single
        !            58: server to provide service to clients on multiple networks.
        !            59: To create a socket which listens on all networks, the Internet
        !            60: address INADDR_ANY
        !            61: must be bound.  The TCP port may still be specified
        !            62: at this time; if the port is not specified the system will assign one.
        !            63: Once a connection has been established the socket's address is
        !            64: fixed by the peer entity's location.   The address assigned the
        !            65: socket is the address associated with the network interface
        !            66: through which packets are being transmitted and received.  Normally
        !            67: this address corresponds to the peer entity's network.
        !            68: .PP
        !            69: TCP supports one socket option which is set with
        !            70: .IR setsockopt (2)
        !            71: and tested with
        !            72: .IR getsockopt (2).
        !            73: Under most circumstances, TCP sends data when it is presented;
        !            74: when outstanding data has not yet been acknowledged, it gathers
        !            75: small amounts of output to be sent in a single packet once
        !            76: an acknowledgement is received.
        !            77: For a small number of clients, such as window systems
        !            78: that send a stream of mouse events which receive no replies,
        !            79: this packetization may cause significant delays.
        !            80: Therefore, TCP provides a boolean option, TCP_NODELAY (from
        !            81: .IR <netinet/tcp.h> ,
        !            82: to defeat this algorithm.
        !            83: The option level for the
        !            84: .I setsockopt
        !            85: call is the protocol number for TCP,
        !            86: available from
        !            87: .IR getprotobyname (3).
        !            88: .PP
        !            89: Options at the IP transport level may be used with TCP; see
        !            90: .IR ip (4).
        !            91: Incoming connection requests that are source-routed are noted,
        !            92: and the reverse source route is used in responding.
        !            93: .SH DIAGNOSTICS
        !            94: A socket operation may fail with one of the following errors returned:
        !            95: .TP 20
        !            96: [EISCONN]
        !            97: when trying to establish a connection on a socket which
        !            98: already has one;
        !            99: .TP 20
        !           100: [ENOBUFS]
        !           101: when the system runs out of memory for
        !           102: an internal data structure;
        !           103: .TP 20
        !           104: [ETIMEDOUT]
        !           105: when a connection was dropped
        !           106: due to excessive retransmissions;
        !           107: .TP 20
        !           108: [ECONNRESET]
        !           109: when the remote peer
        !           110: forces the connection to be closed;
        !           111: .TP 20
        !           112: [ECONNREFUSED]
        !           113: when the remote
        !           114: peer actively refuses connection establishment (usually because
        !           115: no process is listening to the port);
        !           116: .TP 20
        !           117: [EADDRINUSE]
        !           118: when an attempt
        !           119: is made to create a socket with a port which has already been
        !           120: allocated;
        !           121: .TP 20
        !           122: [EADDRNOTAVAIL]
        !           123: when an attempt is made to create a 
        !           124: socket with a network address for which no network interface
        !           125: exists.
        !           126: .SH SEE ALSO
        !           127: getsockopt(2), socket(2), intro(4), inet(4), ip(4)

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