getprotoent(2)                                           getprotoent(2)

  getprotobynumber()

  NAME

    getprotobynumber(), getprotobyname(), getprotoent(), setprotoent(),
    endprotoent() - get protocol entry

  SYNOPSIS

    #include 

    struct protoent * getprotobyname (const char *name)
    struct protoent * getprotobynumber (int proto)
    struct protoent * getprotoent (void)
    void setprotoent (int stayopen)
    void endprotoent (void)

  DESCRIPTION

    The getprotobyname(2) and getprotobynumber(2) functions each return a
    pointer to an object with the following structure containing the
    information from a network protocol database.

    struct protoent {
       char * p_name;       /* official name of protocol */
       char ** p_aliases;   /* alias list */
       int p_proto;         /* protocol number */
    };

    The members of this structure are:

    p_name
        The official name of the protocol.

    p_aliases
        A zero terminated list of alternate names for the protocol.

    p_proto
        The protocol number.

    The getprotobyname(2) function and getprotobynumber(2) sequentially search
    from the beginning of the file until a matching protocol name or protocol
    number is found, or until EOF is encountered.

    The getprotoent(2), setprotoent(2), and endprotoent(2) functions also deal
    with the network database, but on an entry-by-entry basis. The
    getprotoent(2) call reads the next line of the file, opening the file if
    necessary. The setprotoent(2) call opens and rewinds the file. If the
    stayopen flag is non-zero, the network database stays open after each call
    to getprotobyname(2) or getprotobynumber(2). (The default action is to
    close the database after these calls.) The endprotoent(2) call closes the
    file.

  RETURN VALUES

    The functions getprotoent(2), getprotobyname(2), and getprotobynumber(2)
    return pointers to protoent structures.

    All of the function return NULL on failure.

  NOTES

    These functions use a static data space; if the data is needed for future
    use, it should be copied before any subsequent calls overwrite it. Only
    the Internet protocols are currently available.

    The INTERIX sockets implementation is built around the Microsoft Winsock
    DLL; to configure the protocols appropriately, see the documentation for
    configuring your Windows network.

  SEE ALSO

    protocols(5)

  USAGE NOTES

    None of these functions are thread safe.

    None of these functions are async-signal safe.