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

1.1     ! root        1: .\" Copyright (c) 1983 Regents of the University of California.
        !             2: .\" All rights reserved.  The Berkeley software License Agreement
        !             3: .\" specifies the terms and conditions for redistribution.
        !             4: .\"
        !             5: .\"    @(#)tcp.4p      6.2 (Berkeley) 5/16/86
        !             6: .\"
        !             7: .TH TCP 4P "May 16, 1986"
        !             8: .UC 5
        !             9: .SH NAME
        !            10: tcp \- Internet Transmission Control Protocol
        !            11: .SH SYNOPSIS
        !            12: .B #include <sys/socket.h>
        !            13: .br
        !            14: .B #include <netinet/in.h>
        !            15: .PP
        !            16: .B s = socket(AF_INET, SOCK_STREAM, 0);
        !            17: .SH DESCRIPTION
        !            18: The TCP protocol provides reliable, flow-controlled, two-way
        !            19: transmission of data.  It is a byte-stream protocol used to
        !            20: support the SOCK_STREAM abstraction.  TCP uses the standard
        !            21: Internet address format and, in addition, provides a per-host
        !            22: collection of \*(lqport addresses\*(rq.  Thus, each address is composed
        !            23: of an Internet address specifying the host and network, with
        !            24: a specific TCP port on the host identifying the peer entity.
        !            25: .PP
        !            26: Sockets utilizing the tcp protocol are either \*(lqactive\*(rq or
        !            27: \*(lqpassive\*(rq.  Active sockets initiate connections to passive
        !            28: sockets.  By default TCP sockets are created active; to create a
        !            29: passive socket the
        !            30: .IR listen (2)
        !            31: system call must be used
        !            32: after binding the socket with the
        !            33: .IR bind (2)
        !            34: system call.  Only
        !            35: passive sockets may use the 
        !            36: .IR accept (2)
        !            37: call to accept incoming connections.  Only active sockets may
        !            38: use the
        !            39: .IR connect (2)
        !            40: call to initiate connections.
        !            41: .PP
        !            42: Passive sockets may \*(lqunderspecify\*(rq their location to match
        !            43: incoming connection requests from multiple networks.  This
        !            44: technique, termed \*(lqwildcard addressing\*(rq, allows a single
        !            45: server to provide service to clients on multiple networks.
        !            46: To create a socket which listens on all networks, the Internet
        !            47: address INADDR_ANY
        !            48: must be bound.  The TCP port may still be specified
        !            49: at this time; if the port is not specified the system will assign one.
        !            50: Once a connection has been established the socket's address is
        !            51: fixed by the peer entity's location.   The address assigned the
        !            52: socket is the address associated with the network interface
        !            53: through which packets are being transmitted and received.  Normally
        !            54: this address corresponds to the peer entity's network.
        !            55: .PP
        !            56: TCP supports one socket option which is set with
        !            57: .IR setsockopt (2)
        !            58: and tested with
        !            59: .IR getsockopt (2).
        !            60: Under most circumstances, TCP sends data when it is presented;
        !            61: when outstanding data has not yet been acknowledged, it gathers
        !            62: small amounts of output to be sent in a single packet once
        !            63: an acknowledgement is received.
        !            64: For a small number of clients, such as window systems
        !            65: that send a stream of mouse events which receive no replies,
        !            66: this packetization may cause significant delays.
        !            67: Therefore, TCP provides a boolean option, TCP_NODELAY (from
        !            68: .IR <netinet/tcp.h> ,
        !            69: to defeat this algorithm.
        !            70: The option level for the
        !            71: .I setsockopt
        !            72: call is the protocol number for TCP,
        !            73: available from
        !            74: .IR getprotobyname (3N).
        !            75: .PP
        !            76: Options at the IP transport level may be used with TCP; see
        !            77: .IR ip (4P).
        !            78: Incoming connection requests that are source-routed are noted,
        !            79: and the reverse source route is used in responding.
        !            80: .SH DIAGNOSTICS
        !            81: A socket operation may fail with one of the following errors returned:
        !            82: .TP 20
        !            83: [EISCONN]
        !            84: when trying to establish a connection on a socket which
        !            85: already has one;
        !            86: .TP 20
        !            87: [ENOBUFS]
        !            88: when the system runs out of memory for
        !            89: an internal data structure;
        !            90: .TP 20
        !            91: [ETIMEDOUT]
        !            92: when a connection was dropped
        !            93: due to excessive retransmissions;
        !            94: .TP 20
        !            95: [ECONNRESET]
        !            96: when the remote peer
        !            97: forces the connection to be closed;
        !            98: .TP 20
        !            99: [ECONNREFUSED]
        !           100: when the remote
        !           101: peer actively refuses connection establishment (usually because
        !           102: no process is listening to the port);
        !           103: .TP 20
        !           104: [EADDRINUSE]
        !           105: when an attempt
        !           106: is made to create a socket with a port which has already been
        !           107: allocated;
        !           108: .TP 20
        !           109: [EADDRNOTAVAIL]
        !           110: when an attempt is made to create a 
        !           111: socket with a network address for which no network interface
        !           112: exists.
        !           113: .SH SEE ALSO
        !           114: getsockopt(2), socket(2), intro(4N), inet(4F), ip(4P)

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