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TCPIP Services, Programming Interfaces, Sockets API, $QIO, Network Pseudodevice Driver Functions

 *Conan The Librarian (sorry for the slow response - running on an old VAX)

    The network pseudodevice allows physical, logical, and virtual
    I/O functions. The physical and logical I/O functions are used
    only with the IP layer. Network Pseudodevice Driver I/O Functions
    lists the basic I/O functions and their modifiers. The sections
    that follow describe in greater detail the operation of these I/O
    functions.
    Table 1 Network Pseudodevice Driver I/O Functions
    Function Code and    Function
    Arguments            Modifier        Description
    IO$_ACCESS p3,p4     IO$M_ACCEPT     Opens a connection.
                         IO$M_EXTEND
                         IO$M_NOW
    IO$_ACPCONTROL p1,                   Performs an ACP (ancillary
    p2, p3, p4                           control process) operation.
    IO$_DEACCESS p4      IO$M_NOW        Aborts or closes a
                         IO$M_SHUTDOWN   connection.
    IO$_READVBLK         IO$M_EXTEND     Reads a virtual block.
    p1,p2,p3,p4,p6       IO$M_
                         INTERRUPT
                         IO$M_LOCKBUF    Controls the buffer
                         IO$M_PURGE      operations.
    IO$_SENSEMODE                        Reads the network
    p2,p3,p4,p6                          pseudodevice
                                         characteristics.
    IO$_SENSECHAR                        Reads the network
    p2,p3,p4,p6                          pseudodevice
                                         characteristics.
    IO$_SETMODE p1,p2,   IO$M_OUTBAND    Sets the network
    p3,p4,p5             IO$M_READATTN   pseudodevice characteristics
                         IO$M_WRTATTN    for subsequent operations.
    IO$_SETCHAR p1,p2,   IO$M_OUTBAND    Sets the network
    p3,p4,p5             IO$M_READATTN   pseudodevice characteristics
                         IO$M_WRTEATTN   for subsequent operations.
    IO$_WRITEVBLK        IO$M_           Writes a virtual block.
    p1,p2,p3,p4,p5       INTERRUPT
    The following table contains the file names of the symbol
    definition files. These files specify $QIO arguments
    (p1,p2,...p6) for applications written in the corresponding
    programming languages. You must invoke the symbol definition
    by using the appropriate include statement in your application.
    Table 2 Network Symbol Definition Files
    File Name              Language
    <REFERENCE>(filpref)$INDECEC.or VAX C
    <REFERENCE>(filpref)$INVAXEFortran
    <REFERENCE>(filpref)$INVAXEPASCAL
    <REFERENCE>(filpref)$INMACRO-32R
    <REFERENCE>(filpref)$INVAXEPL/1I
    <REFERENCE>(filpref)$INBLISS-322
    <REFERENCE>(filpref)$INVAXEADADA
    <REFERENCE>(filpref)$INVAXEBASIC

  1 - IO$_ACCESS

    When using a connection-oriented protocol, such as TCP, the IO$_
    ACCESS function initiates a connection and specifies a remote
    port number and internet address. When using a connectionless
    protocol, such as UDP, the IO$_ACCESS function sets the remote
    port number and internet address.
    For TCP, a connection request times out at a specified interval
    (75 seconds is the default). This interval can be changed by
    the system manager. The program can also set a specific timeout
    interval for a socket that it has created.
    If a connection fails, you must deallocate the socket and then
    create a new socket before trying to reconnect.
    Related Functions
    The equivalent Sockets API function is connect().

 1.1 - Arguments

 p3
    OpenVMS usage:socket_name
    type:         vector byte (unsigned)
    access:       read only
    mechanism:    by item_list_2 descriptor
    The remote port number and internet address of the host to
    connect. The p3 argument is the address of an item_list_2
    descriptor that points to the socket address structure containing
    the remote port number and internet address.

 1.2 - Function Modifiers

    IO$M_NOW           Regardless of a $QIO or $QIOW, if the system
                       detects a condition that would cause the
                       operation to block, the system completes the
                       I/O operation and returns the SS$_SUSPENDED
                       status code.

 1.3 - Condition Values Returned

    SS$_NORMAL         The service completed successfully.
    SS$_BADPARAM       Programming error that occurred for one of the
                       following reasons:
                       o  $QIO system service was specified without a
                          socket.
                       o  An IO$_ACCESS function was specified
                          without the address of a remote socket
                          name (p3 was null).
    SS$_BUGCHECK       Inconsistent state. Report the problem to your
                       Compaq support representative.
    SS$_CANCEL         The I/O operation was canceled by a $CANCEL
                       system service.
    SS$_CONNECFAIL     The connection to a network object timed out
                       or failed.
    SS$_DEVINTACT      The network driver was not started.
    SS$_DEVNOTMOUNT    The network driver is loaded, but the INETACP
                       is not currently available for use.
    SS$_DUPLNAM        A network configuration error. No ports were
                       available for new connections.
    SS$_EXQUOTA        The process has exceeded its socket quota or
                       some other process quota.
    SS$_FILALRACC      The specified socket name is already in use by
                       one of the following:
                       o  On a raw socket, the remote internet
                          address was already specified on a previous
                          IO$_ACCESS call.
                       o  On a datagram, the remote internet address
                          was already specified on a previous
                          IO$_ACCESS call.
                       o  On a stream socket, the IO$_ACCESS function
                          targeted a stream socket that was already
                          connected.
    SS$_ILLCNTRFUNC    Illegal function.
    SS$_INSFMEM        Insufficient system dynamic memory to complete
                       the service.
    SS$_IVADDR         The specified internet address was not found,
                       or an invalid port number and internet address
                       combination was specified with the IO$_ACCESS
                       function. Port 0 is not allowed with the
                       IO$_ACCESS function.
    SS$_IVBUFLEN       The size of the socket name structure
                       specified with the IO$_ACCESS function was
                       invalid.
    SS$_LINKABORT      The remote socket closed the connection.
    SS$_NOLICENSE      The Compaq TCP/IP Services for OpenVMS license
                       is not present.
    SS$_PROTOCOL       A network protocol error occurred. The
                       address family specified in the socket address
                       structure is not supported.
    SS$_REJECT         The network connection is rejected for one of
                       the following reasons:
                       o  An attempt was made to connect to a remote
                          socket that is already connected.
                       o  An error was encountered while establishing
                          the connection
                       o  The peer socket refused the connection
                          request or is closing the connection.
    SS$_SHUT           The local or remote node is no longer
                       accepting connections.
    SS$_SUSPENDED      The system detected a condition that might
                       cause the operation to block.
    SS$_TIMEOUT        A TCP connection timed out before the
                       connection could be established.
    SS$_UNREACHABLE    The remote node is currently unreachable.

  2 - IO$_ACCESS|IO$M_ACCEPT

    This function is used with a connection-based protocol, such as
    TCP, to accept a new connection on a passive socket.
    This function completes the first connection on the queue of
    pending connections.
    Related Functions
    The equivalent Sockets API function is accept() .

 2.1 - Arguments

 p3
    OpenVMS usage:socket_name
    type:         vector byte (unsigned)
    access:       read only
    mechanism:    by item_list_3 descriptor
    The remote port number and internet address of a new connection.
    The p3 argument is the address of an item_list_3 descriptor that
    points to the socket address structure into which the remote port
    number and internet address of the new connection is written.
    Use the IO$_ACCESS function with the IO$M_EXTEND modifier to
    specify a BSD Version 4.4 formatted socket address structure.
 p4
    OpenVMS usage:channel
    type:         word (unsigned)
    access:       write only
    mechanism:    by reference
    The I/O channel number assigned to a new connection. The p4
    argument is the address of a word into which the new connection's
    channel number is written.

 2.2 - Function Modifiers

    IO$M_EXTEND        Allows the usage of BSD Version 4.4 formatted
                       socket address structures.
    IO$M_NOW           Regardless of a $QIO or $QIOW, if the system
                       detects a condition that would cause the
                       operation to block, the system completes the
                       I/O operation and returns the SS$_SUSPENDED
                       status code.

 2.3 - Condition Values Returned

    SS$_NORMAL         The service completed successfully.
    SS$_BADPARAM       Programming error that occurred for one of the
                       following reasons:
                       o  $QIO system service was specified without a
                          socket.
                       o  A IO$_ACCESS|IO$M_ACCEPT function was
                          specified without the address of the
                          channel for the new connection (p4 was
                          null or invalid).
    SS$_BUGCHECK       Inconsistent state. Report the problem to your
                       Compaq support representative.
    SS$_CANCEL         The I/O operation was canceled by a $CANCEL
                       system service.
    SS$_DEVINTACT      The network driver was not started.
    SS$_DEVNOTMOUNT    The network driver is loaded, but the INETACP
                       is not currently available for use.
    SS$_EXQUOTA        The process has exceeded its socket quota or
                       some other process quota.
    SS$_FILALRACC      The specified socket name is already in use by
                       one of the following:
                       o  On a raw socket, the remote internet
                          address was already specified on a previous
                          IO$_ACCESS call.
                       o  On a datagram, the remote internet address
                          was already specified on a previous
                          IO$_ACCESS call.
                       o  On a stream socket, the IO$_ACCESS function
                          targeted a stream socket that was already
                          connected.
    SS$_ILLCNTRFUNC    Illegal function.
    SS$_INSFMEM        Insufficient system dynamic memory to complete
                       the service.
    SS$_IVADDR         The specified internet address was not found,
                       or an invalid port number and internet address
                       combination was specified with the IO$_ACCESS
                       function. Port 0 is not allowed with the
                       IO$_ACCESS function.
    SS$_IVBUFLEN       The size of the socket name structure
                       specified with the IO$_ACCESS function was
                       invalid.
    SS$_LINKABORT      The remote socket closed the connection.
    SS$_NOLICENSE      The TCP/IP Services license is not present.
    SS$_PROTOCOL       A network protocol error occurred. The
                       address family specified in the socket address
                       structure is not supported.
    SS$_REJECT         The network connection is rejected for one of
                       the following reasons:
                       o  An attempt was made to connect to a remote
                          socket that is already connected.
                       o  An error was encountered while establishing
                          the connection
                       o  The peer socket refused the connection
                          request or is closing the connection.
    SS$_SHUT           The local or remote node is no longer
                       accepting connections.
    SS$_SUSPENDED      The system detected a condition that might
                       cause the operation to block.
    SS$_TIMEOUT        A TCP connection timed out before the
                       connection could be established.
    SS$_UNREACHABLE    The remote node is currently unreachable.

  3 - IO$_ACPCONTROL

    The IO$_ACPCONTROL function accesses the network ACP to retrieve
    information from the host and the network database files.
    Related Functions
    The equivalent Sockets API functions are gethostbyaddr(),
    gethostbyname(), getnetbyaddr(),  and getnetbyname().

 3.1 - Arguments

 p1
    OpenVMS usage:subfunction_code
    type:         longword (unsigned)
    access:       read only
    mechanism:    by descriptor-fixed-length descriptor
    A longword identifying the network ACP operation to perform.
    The p1 argument is the address of a descriptor pointing to this
    longword.
    To specify the network ACP operation to perform, select a
    subfunction code from Subfunction Codes and a call code from
    Call Codes.
    Subfunction Codes defines subfunction codes for network ACP
    operations.
    Table 3 Subfunction Codes
    Subfunction Code            Description
    INETACP_FUNC$C_             Get the host name of the specified
    GETHOSTBYADDR               internet address from the host
                                database.
    INETACP_FUNC$C_             Get the internet address of the
    GETHOSTBYNAME               specified host from the host
                                database.
    INETACP_FUNC$C_             Get the network name of the specified
    GETNETBYADDR                internet address from the network
                                database.
    INETACP_FUNC$C_             Get the internet address of the
    GETNETBYNAME                specified network from the network
                                database.
    Call Codes defines call codes for network ACP operations.
    Table 4 Call Codes
    Call Code              Description
    INETACP$C_ALIASES      Returns the list of alias names associated
                           with the specified host or network from
                           the internet hosts or network database.
    INETACP$C_TRANS        Returns the internet address associated
                           with the specified host or network as a
                           32-bit value in network byte order.
    INETACPC$C_HOSTENT_    Returns full host information in a
    OFFSET                 modified hostent structure. In the
                           modified structure, pointers are replaced
                           with offsets from the beginning of the
                           structure.
    INETACP$C_NETENT_      Returns full network information in
    OFFSET                 a modified netent structure. In the
                           modified structure, pointers are replaced
                           with offsets from the beginning of the
                           structure.
    IO$_ACPCONTROL searches the local host database for the host's
    name. If a matching host name is not found in the local host
    database, IO$_ACPCONTROL then searches the BIND database if the
    BIND resolver is enabled.
 p2
    OpenVMS usage:char_string
    type:         character-coded text string
    access:       read only
    mechanism:    by descriptor-fixed-length string descriptor
    Input string for the network ACP operation containing one of the
    following: host internet address, host name, network internet
    address, or network name. The p2 argument is the address of a
    string descriptor pointing to the input string.
    All internet addresses are specified in dotted-decimal notation.
 p3
    OpenVMS usage:word_unsigned
    type:         word (unsigned)
    access:       write only
    mechanism:    by reference
    Length in bytes of the output buffer returned by IO$_ACPCONTROL.
    The p3 argument is the address of a word in which the length of
    the output buffer is written.
 p4
    OpenVMS usage:buffer
    type:         vector byte (unsigned)
    access:       write only
    mechanism:    by descriptor-fixed-length descriptor
    Buffer into which IO$_ACPCONTROL writes its output data. The p4
    argument is the address of a descriptor pointing to the output
    buffer.
    The format of the data returned in the output buffer is dictated
    by the call code specified by the p1 argument.
    o  Strings returned by IO$_ACPCONTROL with a call code of
       INETACP$C_ALIASES consist one of the following: host internet
       address, host name, network internet address, or network name.
       All internet addresses are formatted using dotted-decimal
       notation. Alias names are separated by a null character (0).
       The length of the returned string includes all null characters
       that separate alias names.
    o  Internet addresses returned by IO$_ACPCONTROL with a call code
       of INETACP$C_TRANS are 32-bit value and in network byte order.
    o  All hostent and netent structures returned by IO$_ACPCONTROL
       with a call code of INETACP$C_HOSTENT_OFFSET or INETACP$C_
       NETENT_OFFSET are modified; pointers are replaced with offsets
       from the beginning of the structure.

 3.2 - Condition Values Returned

    SS$_NORMAL         The service completed successfully
    SS$_ABORT          An error was detected while performing an ACP
                       function.
    SS$_BADPARAM       Programming or internal error. A bad
                       parameter (name or address) was specified
                       in a GET{HOST,NET}BY{NAME,ADDRESS} ACP call.
    SS$_BUFFEROVF      Programming error. There was not enough space
                       for returning all alias names in a
                       GET{HOST,NET}BY{NAME,ADDRESS} ACP call.
    SS$_ENDOFFILE      The information requested is not in the
                       database.
    SS$_ILLCNTRFUNC    Illegal function.
    SS$_NOPRIV         No privilege for the execution of an ACP
                       function.
    SS$_RESULTOVF      The ACP overflowed the buffer in returning a
                       parameter.
    SS$_SHUT           The local or remote node is no longer
                       accepting connections.

  4 - IO$_DEACCESS

    The IO$_DEACCESS function closes a connection and deletes a
    socket. Any pending messages queued for transmission are sent
    before tearing down the connection.
    When used with the IO$M_SHUTDOWN function modifier, the IO$_
    DEACCESS function shuts down all or part of a bidirectional
    connection on a socket. Use the p4 argument to specify the
    disposition of pending I/O operations on the socket.
    You can specify a wait time or time-to-linger socket parameter
    (TCPIP$C_LINGER option) for transmission completion before
    disconnecting the connection. Use the IO$_SETMODE or IO$_SETCHAR
    function to set and clear the TCPIP$C_LINGER option.
    If you set the TCPIP$C_LINGER option, a $QIO call that uses the
    IO$_DEACCESS function allows data queued to the socket to arrive
    at the destination. The system is blocked until data arrives at
    the remote socket. The socket data structure remains open for the
    duration of the TCP idle time interval.
    If you do not set the TCPIP$C_LINGER option (option is set to 0),
    a $QIO call that uses the IO$_DEACCESS function discards any data
    queued to the socket and deallocates the socket data structure.
                                   NOTE
       For compatibility with Compaq Tru64 UNIX, the TCP/IP
       Services forces a time to linger of 2 minutes on TCP stream
       sockets.
    Related Functions
    The equivalent Sockets API functions are close() and shutdown().

 4.1 - Arguments

 p4
    OpenVMS usage:mask_longword
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    Longword of shutdown flags to specify the disposition of pending
    I/O operations on the socket. The p4 argument is used only with
    the IO$M_SHUTDOWN function modifier. The following table lists
    available shutdown flags.
    Shutdown Flag   Description
    TCPIP$C_DSC_    Discards messages from the receive queue and
    RCV             disallows further receiving. Pending messages
                    in the receive queue for this connection are
                    discarded.
    TCPIP$C_DSC_    Discards messages from the send queue and
    SND             disallows sending new messages. Pending messages
                    in the transmit queue for this connection are
                    discarded.
    TCPIP$C_DSC_    Discards all messages and disallows both
    ALL             sending and receiving. All pending messages are
                    discarded.
                    Specifying this flag has the same effect as
                    issuing a $CANCEL QIO followed by an IO$_DEACCESS
                    QIO without specifying any flags.

 4.2 - Function Modifiers

    IO$M_SHUTDOWN      Causes all or part of a full-duplex connection
                       on a socket to be shut down.
    IO$M_NOW           Regardless of a $QIO or $QIOW, if the system
                       detects a condition that would cause the
                       operation to block, the system completes the
                       I/O operation and returns the SS$_SUSPENDED
                       status code.

 4.3 - Condition Values Returned

    SS$_NORMAL         The service completed successfully.
    SS$_BADPARAM       The IO$_DEACCESS operation failed to specify a
                       socket.
    SS$_CANCEL         The I/O operation was canceled by a $CANCEL
                       system service.
    SS$_DEVINTACT      The network driver was not started.
    SS$_DEVNOTMOUNT    The network driver is loaded, but the INETACP
                       is not currently available for use.
    SS$_NOLINKS        The specified socket was not connected.
    SS$_SHUT           The local or remote node is no longer
                       accepting connections.
    SS$_SUSPENDED      The system detected a condition that might
                       cause the operation to block.

  5 - IO$_READVBLK

    The IO$_READVBLK function transfers data received from an
    internet host to the specified user buffers. Use both p1 and
    p2 arguments to specify a single user buffer. Use the p6 argument
    to specify multiple buffers.
    For connection-oriented protocols, such as TCP, data is buffered
    in system space as a stream of bytes. The IO$_READVBLK function
    completes (1) when there is no more data buffered in system space
    for this socket, or (2) when there is no more available space in
    the user buffer. Data that is buffered in system space but did
    not fit in the user buffer is available to the user in subsequent
    $QIOs.
    For connectionless protocols, datagram and raw socket data is
    buffered in system space as a chain of records. The user buffer
    specified with a IO$_READVBLK function is filled with data that
    is buffered in one record. Each IO$_READVBLK reads data from one
    record. The IO$_READVBLK function completes (1) when all data
    from a record is transferred to the user buffer, or (2) when
    there is no more available space in the user buffer. Any data
    remaining in the current record that did not fit in the user
    buffer is discarded. A subsequent $QIO reads data from the next
    record buffered in system space.
    Use the management command SHOW DEVICE_SOCKET/FULL to display
    counters related to read operations.
    Related Functions
    The equivalent Sockets API functions are read(), recv(),
    recvfrom(), and recvmsg().

 5.1 - Arguments

 p1
    OpenVMS usage:buffer
    type:         vector byte (unsigned)
    access:       read only
    mechanism:    by 32- or 64-bit reference (Alpha)
                  by 32-bit reference (VAX)
    The 32- or 64-bit address (on Alpha systems) or the 32-bit
    address (on VAX systems) of the buffer to receive the incoming
    data. The length of this buffer is specified by the p2 argument.
 p2
    OpenVMS usage:buffer_length
    type:         quadword unsigned (Alpha); longword unsigned (VAX)
    access:       read only
    mechanism:    by 64-bit value (Alpha)
                  by 32-bit value (VAX)
    The length (in bytes) of the buffer available to hold the
    incoming data. The address of this buffer is specified by the
    p1 argument.
 p3
    OpenVMS usage:socket_name
    type:         vector byte (unsigned)
    access:       read only
    mechanism:    by item_list_3 descriptor
    The remote port number and internet address of the source of
    the datagram or raw IP message (not TCP). The p3 argument is the
    address of an item_list_3 descriptor that points to the socket
    address structure into which the remote port number and internet
    address of the message source is written.
    Use the IO$_READVBLK function with the IO$M_EXTEND modifier to
    specify a BSD Version 4.4 formatted socket address structure.
    If the IO$M_EXTEND modifier is not specified, the IO$_READVBLK
    function returns a BSD Version 4.3 formatted socket address
    structure.
 p4
    OpenVMS usage:mask_longword
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    Longword of flags to specify attributes for the read operations.
    Read Flags lists the available read flags.
    Table 5 Read Flags
    Read Flag          Description
    TCPIP$C_MSG_OOB    Reads an out-of-band byte.
    TCPIP$C_MSG_PEEK   Reads a message but leaves the message in the
                       queue.
    TCPIP$C_MSG_NBIO   Does not block the I/O operation if the
                       receive queue is empty (similar to using
                       IO$M_NOWAIT).
    TCPIP$C_MSG_PURGE  Flushes data from the queue (similar to using
                       IO$M_PURGE).
    TCPIP$C_MSG_       Blocks the completion of the operation until
    BLOCKALL           the buffer is filled completely or until the
                       connection is closed (similar to using IO$M_
                       LOCKBUF).
 p6
    OpenVMS usage:buffer_list
    type:         vector byte (unsigned)
    access:       read only
    mechanism:    by 32- or 64-bit descriptor-fixed-length descriptor
                  (Alpha)
                  by 32-bit descriptor-fixed-length descriptor (VAX)
    Output buffer list describing one or more buffers to hold the
    incoming data. The p6 argument is the 32- or 64-bit address
    (on Alpha systems) or the 32-bit address (on VAX systems) of
    a descriptor that points to a output buffer list. Buffers are
    filled in the order specified by the output buffer list. The
    transfer-length value returned in the I/O status block is the
    total number of bytes transferred to all buffers.
    If you use the p1 and p2 arguments, do not use the p6 argument;
    they are mutually exclusive.

 5.2 - Function Modifiers

    IO$M_EXTEND        Specifies the format of the socket address
                       structure to return when used with the p3
                       argument.
                       When specified, a BSD Version 4.4 formatted
                       socket address structure is returned that
                       identifies the source of the received UDP
                       datagram or raw IP message.
    IO$M_INTERRUPT     Reads an out-of-band (OOB) message. This
                       has the same effect as specifying the
                       TCPIP$C_MSG_OOB flag in the p4 argument.
                       On receiving a TCP/IP OOB character, TCP/IP
                       stores the pointer in the received stream with
                       the character that precedes the OOB character.
                       A read operation with a user-buffer size
                       larger than the size of the received stream
                       up to the OOB character completes and returns
                       to the user the received stream up to, but not
                       including, the OOB character.
                       To determine whether the socket must issue
                       more read $QIOs before getting all the
                       characters from the stream preceding an OOB
                       character, poll the socket. To do this, issue
                       a $QIO with the $IO_SENSEMODE function, and
                       the TCPIP$C_IOCTL subfunction that specifies
                       the SIOCATMARK command. The SIOCATMARK values
                       are as follows:
                       o  0 = Issue more read QIOs to read more data
                          before reading the OOB.
                       o  1 = The next read QIO will return the OOB.
                       Polling a socket is particularly useful
                       when the OOBINLINE socket option is set.
                       When the OOBINLINE is set, TCP/IP reads the
                       OOB character with the characters in the
                       stream (IO$_READVBLK), but not before reading
                       the preceding characters. Use this polling
                       mechanism to determine whether the first
                       character in the user buffer on the next read
                       is an OOB character.
                       On a socket without the OOBINLINE option
                       set, a received OOB will always be
                       read by issuing a $QIO with either the
                       IO$_READVBLK|IO$M_INTERRUPT or IO$_READVBLK
                       and the TCPIP$C_MSG_OOB flag set. This
                       can occur regardless of how many preceding
                       characters in the stream have been returned to
                       the user.
    IO$M_LOCKBUF       Blocks the completion of the I/O operation
                       until the user buffer is completely filled
                       or until the connection is closed. This
                       is particularly useful when you want to
                       minimize the number of $QIO service calls
                       issued to read a data stream of a set size.
                       This function modifier supports only stream
                       protocols.
    IO$M_NOWAIT        Regardless of a $QIO or $QIOW, if the
                       system detects a condition that would
                       cause the operation to block, the system
                       completes the I/O operation and returns the
                       SS$_SUSPENDED status code.
    IO$M_PURGE         Flushes data from the socket receive queue
                       (discards data). If the user buffer is larger
                       than the amount of data in the queue, all data
                       is flushed.

 5.3 - Condition Values Returned

    SS$_NORMAL         The service completed successfully.
    SS$_ABORT          Programming error, INET management error, or
                       hardware error. The execution of the I/O was
                       aborted.
    SS$_ACCVIO         Access to an invalid memory location or buffer
                       occurred.
    SS$_BADPARAM       One of the following methods was used to
                       specify a $QIO function with an invalid
                       parameter:
                       o  An I/O function executed without specifying
                          a device socket. First issue a $QIO with
                          the IO$_SETMODE function and the proper
                          parameters to create the device socket.
                       o  An IO$_READVBLK function that does not
                          specify a correct buffer address (p1 or p6
                          is null).
                       o  An IO$_READVBLK function specified an
                          invalid vectored buffer (p6 is an invalid
                          descriptor).
                       o  The socket has the OOBINLINE option set,
                          or there is no OOB character in the
                          socket's OOB queue because the character
                          was either already read or never received.
                          This condition happens only if you use
                          the IO$M_INTERRUPT modifier or set the
                          TCPIP$C_MSG_OOB flag with IO$_READVBLK.
    SS$_CANCEL         The I/O operation was canceled by a $CANCEL
                       system service.
    SS$_DEVINTACT      The network driver was not started.
    SS$_DEVNOTMOUNT    The network driver is loaded, but the INETACP
                       is not currently available for use.
    SS$_INSFMEM        INET management or programming error. There
                       is not enough buffer space for allocation.
                       The INET software needs more buffer space.
                       You should set a higher quota for the dynamic
                       buffer space, or shut down and restart your
                       internet with a larger static buffer space.
    SS$_IVBUFLEN       Programming error occurred for one of the
                       following reasons:
                       o  The size of the buffer for an I/O function
                          is insufficient.
                       o  An IO$_READVBLK specified a correct buffer
                          address (p1 valid), but does not specify a
                          buffer length (p2 is null).
    SS$_LINKDISCON     A virtual circuit (TCP/IP) was closed at the
                       initiative of the peer.
    SS$_NOLINKS        Programming error. Read attempt on unconnected
                       TCP socket.
    SS$_SHUT           The network is being shut down.
    SS$_SUSPENDED      The operation is blocked for one of the
                       following reasons:
                       o  No messages were received, so the receive
                          operation cannot complete. The socket is
                          marked as nonblocking.
                       o  The socket has the OOBINLINE option clear,
                          and the OOB character has already been
                          read.
    SS$_TIMEOUT        This applies to a socket that has KEEPALIVE
                       set. The connection was idle for longer
                       than the timeout interval (10 minutes is the
                       default).
    SS$_UNREACHABLE    Communication status. The remote host or
                       network is unreachable.

  6 - IO$_SENSEMODE/IO$_SENSECHAR

    The IO$_SENSEMODE and IO$_SENSECHAR functions return one or more
    parameters (characteristics) pertaining to the network driver.
    Socket names (local and remote peer) are returned by using IO$_
    SENSEMODE's p3 and p4 arguments. Other parameters such as socket
    and protocol options, are specified in an output parameter list
    using the IO$_SENSEMODE p6 argument.
    IO$_SENSEMODE p3 and p4 arguments can be used with the p6
    argument in a single $QIO system service to return socket names
    as well as socket and protocol options. IO$_SENSEMODE processes
    arguments in this order: p3, p4, p6. If IO$_SENSEMODE detects an
    error, the IOSB contains the error and argument address or the
    value that was at fault.
    Refer to individual argument descriptions for details about
    specifying the type and format of output parameters.

 6.1 - Arguments

 p3
    OpenVMS usage:socket_name
    type:         vector byte (unsigned)
    access:       read only
    mechanism:    by item_list_3 descriptor
    The port number and internet address of the local name associated
    with the socket. The p3 argument is the address of an item_list_3
    descriptor that points to the socket address structure into which
    the local name is written.
    Use the IO$_SENSEMODE function with the IO$M_EXTEND modifier to
    specify a BSD Version 4.4 formatted socket address structure.
    Related Functions
    The Sockets API equivalent for this function is getsockname().
 p4
    OpenVMS usage:socket_name
    type:         vector byte (unsigned)
    access:       read only
    mechanism:    by item_list_3 descriptor
    The port number and internet address of the remote name
    associated with the socket's peer. The p3 argument is the address
    of an item_list_3 descriptor that points to the socket address
    structure into which the peer name is written.
    Use the IO$_SENSEMODE function with the IO$M_EXTEND modifier to
    specify a BSD Version 4.4 formatted socket address structure.
    Related Functions
    The equivalent Sockets API function is getpeername().
 p6
    OpenVMS usage:output_parameter_list
    type:         vector byte (unsigned)
    access:       read only
    mechanism:    by item_list_2 descriptor
    Output parameter list describing one or more parameters to
    return. The p6 argument is the address of an item_list_2
    descriptor that points to and identifies the type of output
    parameter list.
    The following are the types of output parameter lists:
    Symbolic Name      Output Parameter List Type
    TCPIP$C_SOCKOPT    Socket options
    TCPIP$C_TCPOPT     TCP protocol options
    TCPIP$C_IPOPT      IP protocol options
    TCPIP$C_IOCTL      I/O control commands
    Each item_list_3 structure appearing in an output parameter
    list describes an individual parameter or item to return. See
    <REFERENCE>(op_setsock_tab) for details about socket option
    parameters; see <REFERENCE>(tcp_set_tab_opt) for TCP protocol
    option parameters; and see <REFERENCE>(ip_set_tab_opt) for
    IP protocol option parameters. Unsupported socket or protocol
    options are ignored.
    Each ioctl_com structure that appears in an output parameter list
    contains an I/O control command - the get IOCTL request code and
    its associated IOCTL structure address. See <REFERENCE>(ioctl_
    cmds2) for details about IOCTL command parameters.
    Unsupported socket options are ignored.
    The equivalent Sockets API functions are getsockopt() and
    ioctl().

 6.2 - Function Modifiers

    IO$M_EXTEND        Specifies the format of the socket address
                       structure to return when used with the p3 or
                       p4 arguments.
                       When specified, a BSD Version 4.4 formatted
                       socket address structure is returned.

 6.3 - Condition Values Returned

    SS$_NORMAL         The service completed successfully.
    SS$_ACCVIO         The service cannot access a buffer specified
                       by one or more arguments.
    SS$_BADPARAM       Programming error occurred for one of the
                       following reasons:
                       o  $QIO system service was specified without a
                          socket.
                       o  Error occurred processing a socket or
                          protocol option.
    SS$_DEVINTACT      The network driver was not started.
    SS$_DEVNOTMOUNT    The network driver is loaded, but the INETACP
                       is not currently available for use.
    SS$_ILLCNTRFUNC    Programming error. The operation is
                       unsupported for one of the following reasons:
                       o  An invalid IO$_SENSEMODE function for the
                          interface was specified. The interface does
                          not have an IOCTL routine.
                       o  An IO$_SENSEMODE function that requires a
                          socket was specified, but the device did
                          not have one. Create a socket and then
                          issue the function.
                       o  An unsupported operation was performed on
                          at least one of the following protocols:
                          raw IP, datagram, or stream sockets.
    SS$_INSFMEM        Insufficient system dynamic memory to complete
                       the service.
    SS$_IVBUFLEN       The size of a socket option buffer specified
                       with the IO$_SENSEMODE function was invalid.
    SS$_NOSUCHDEV      Programming error or INET management error. An
                       INET address is not in the Address Resolution
                       Protocol (ARP) table. An attempt to show or
                       delete an ARP table entry failed.
    SS$_NOLINKS        The specified socket was not connected.
    SS$_NOOPER         Programming error. An attempt to get ARP
                       information occurred without OPER privilege.
    SS$_PROTOCOL       A network protocol error occurred. The
                       address family specified in the socket address
                       structure is not supported.
    SS$_SHUT           The local or remote node is no longer
                       accepting connections.
    SS$_UNREACHABLE    The remote node is currently unreachable.

  7 - IO$_SETMODE/IO$_SETCHAR

    The IO$_SETMODE and IO$_SETCHAR functions set one or more
    parameters (characteristics) pertaining to the network driver.
    Sockets are created using the IO$_SETMODE p1 argument. Names are
    assigned to sockets using the IO$_SETMODE p3 argument. Active
    sockets are converted to passive sockets using the IO$_SETMODE p4
    argument. Other parameters, such as socket and protocol options,
    are specified in an input parameter list using the IO$_SETMODE p5
    argument.
    The IO$_SETMODE p1, p3, and p4 arguments can be used with the
    p5 argument in a single $QIO system service to set socket names
    as well as socket and protocol options. IO$_SETMODE processes
    arguments in this order: p1, p3, p4, p5. If IO$_SETMODE detects
    an error, the IOSB contains the error and argument address or the
    value that was at fault.
    Refer to individual argument descriptions for details about
    specifying the type and format of input parameters.

 7.1 - Arguments

 p1
    OpenVMS usage:socket_characteristics
    type:         longword (unsigned)
    access:       read only
    mechanism:    by reference
    Longword specifying the protocol, socket type, and address
    family, of a new socket. The p1 argument is the address of the
    longword containing the socket characteristics.
    The newly created socket is marked privileged if the image that
    creates a socket runs in a process that has a privileged UIC or
    has BYPASS, OPER, or SYSPRV privilege.
    The following table shows protocol codes:
    Protocol       Description
    TCPIP$C_TCP    TCP/IP protocol
    TCPIP$C_UDP    UDP/IP protocol
    TCPIP$C_RAW_   IP protocol
    IP
    Socket Types lists the valid socket types.
    Table 6 Socket Types
    Socket Type      Description
    TCPIP$C_STREAM   Permits bidirectional, reliable, sequenced,
                     and unduplicated data flow without record
                     boundaries.
    TCPIP$C_DGRAM    Permits bidirectional data flow with record
                     boundaries. No provisions for sequencing,
                     reliability, or unduplicated messages.
    TCPIP$C_RAW      Permits access to the IP layer; used to develop
                     new protocols that are layered upon the IP
                     layer.
    The following table shows address family codes:
    Address
    Family         Description
    TCPIP$C_AF_    Internet domain (default).
    INET
    TCPIP$C_AUXS   Accept hand-off of a socket already created and
                   initialized by the auxiliary server.
    Related Functions
    The equivalent Sockets API function is socket().
 p3
    OpenVMS usage:socket_name
    type:         vector byte (unsigned)
    access:       read only
    mechanism:    by item_list_2 descriptor
    The local name (that is, port number and internet address) to
    assign to the socket. The p3 argument is the address of an item_
    list_2 descriptor that points to the socket address structure
    containing the local name.
    Related Functions
    The equivalent Sockets API function is bind() .
 p4
    OpenVMS usage:connection_backlog
    type:         byte (unsigned)
    access:       read only
    mechanism:    by value
    Maximum limit of outstanding connection requests for a socket
    that is connection oriented. If more connection requests are
    received than are specified, the additional requests are ignored
    so that TCP retries can succeed.
    Related Functions
    The equivalent Sockets API function is listen().
 p5
    OpenVMS usage:input_parameter_list
    type:         vector byte (unsigned)
    access:       read only
    mechanism:    by item_list_2 descriptor
    Input parameter list describing one or more parameters to set.
    The p5 argument is the address of an item_list_2 descriptor that
    points to and identifies the type of input parameter list.
    The following are the types of input parameter lists:
    Symbolic Name      Input Parameter List Type
    TCPIP$C_SOCKOPT    Socket options
    TCPIP$C_TCPOPT     TCP protocol options
    TCPIP$C_IPOPT      IP protocol options
    TCPIP$C_IOCTL      I/O control commands
    Each item_list_2 structure appearing in an input parameter
    list describes an individual parameter or item to set. See
    <REFERENCE>(op_setsock_tab) for details about socket option
    parameters; see <REFERENCE>(tcp_set_tab_opt) for TCP protocol
    option parameters; and see <REFERENCE>(ip_set_tab_opt) for
    details about IP protocol option parameters. Unsupported socket
    or protocol options are ignored.
    Each ioctl_com structure that appears in an input parameter list
    contains an I/O control command - the set IOCTL request code and
    its associated IOCTL structure address. See <REFERENCE>(ioctl_
    cmds2) for details about IOCTL command parameters.
    You can use one $QIO system call to set up several socket options
    at once.
    Unsupported socket options are ignored.
    To execute set IOCTL operations, you need a system UIC or SYSPRV,
    BYPASS, or OPER privilege.
    Related Functions
    The equivalent Sockets API functions are setsockopt() and
    ioctl().

 7.2 - Condition Values Returned

    SS$_NORMAL         The service completed successfully.
    SS$_ACCVIO         The service cannot access a buffer specified
                       by one or more arguments.
    SS$_BADPARAM       Programming error that occurred for one of the
                       following reasons:
                       o  $QIO system service was specified without a
                          socket.
                       o  Error occurred processing a socket or
                          protocol option.
    SS$_DEVINTACT      The network driver was not started.
    SS$_DEVNOTMOUNT    The network driver is loaded, but the INETACP
                       is not currently available for use.
    SS$_DUPLNAM        Programming error. The port being bound is
                       already in use. An attempt to bind the socket
                       to an address and port failed.
    SS$_EXQUOTA        Programming or INET management error occurred
                       for one of the following reasons:
                       o  An attempt to create a new socket with
                          the IO$_SETMODE function occurred, but the
                          maximum number of sockets was exceeded.
                          Increase the maximum number of sockets
                          (INET parameter).
                       o  The number of sockets specified with the
                          IO$_SETMODE (listen) exceeds the maximum
                          number of sockets. Increase the maximum
                          number of sockets (INET parameter), or
                          reduce the listen parameter (the number of
                          sockets the listener socket can create).
    SS$_FILALRACC      Programming error. The INET address is already
                       in use. An attempt to bind the socket to an
                       address and port failed.
    SS$_ILLCNTRFUNC    Programming error. The operation is not
                       supported for one of the following reasons:
                       o  An invalid IO$_SETMODE function for the
                          interface occurred that does not have an
                          IOCTL routine.
                       o  An attempt to perform an IO$_SETMODE
                          function required a socket, but the device
                          did not have one. Create a socket before
                          issuing the function.
    SS$_IVADDR         Programming error. The INET address you
                       specified using the IO$_SETMODE function was
                       not placed into the system. This resulted
                       in an invalid port number or INET address
                       combination. The INET address was invalid for
                       one of the following reasons:
                       o  Port zero and INET address zero are not
                          allowed, or port zero is not allowed
                          when using an IO$_ACCESS or IO$_WRITEVBLK
                          function.
                       o  An attempt to exceed the limit of allowable
                          permanent entries in the ARP table
                          occurred.
                       o  An attempt to bind a raw IP socket when
                          there are no interfaces defined in the
                          system occurred.
                       o  An attempt to bind a raw IP socket to a
                          null INET address occurred.
    SS$_INSFMEM        Insufficient system dynamic memory to complete
                       the service.
    SS$_IVBUFLEN       The size of a socket option buffer specified
                       with the IO$_SETMODE function was invalid.
    SS$_NOLICENSE      Programming or system management error. A
                       TCP/IP Services license is not present.
    SS$_NOOPER         Programming or INET management error. An
                       attempt to execute an I/O function that needs
                       the OPER privilege occurred.
    SS$_NOPRIV         Programming or INET management error. There
                       are not enough privileges for the attempted
                       operation for one of the following reasons:
                       o  An attempt to broadcast an IP datagram on
                          a process without a system UIC or SYSPRV,
                          BYPASS, or OPER privilege occurred.
                       o  An attempt to use a reserved port number
                          lower than 1024 occurred.
                       o  An attempt to access a process that
                          requires a system UIC or SYSPRV, or BYPASS
                          privilege occurred.
                       o  An attempt to use raw IP on a privileged
                          socket that requires the SYSPRV or BYPASS
                          privilege occurred.
    SS$_NOSUCHDEV      Programming error or INET management error. An
                       attempt to show or delete an ARP table entry
                       failed because the INET address is not found.
    SS$_NOSUCHNODE     Programming error or INET management error.
                       An attempt to delete a route from the routing
                       table failed because the entry was not found.
    SS$_PROTOCOL       Programming error. A specified protocol or
                       address family caused an error for one of the
                       following reasons:
                       o  An invalid protocol type was specified at
                          socket creation.
                       o  An unsupported protocol was specified.
                       o  A protocol type that was not found in the
                          internal tables was specified.
                       o  The address family is unsupported for one
                          of the following reasons:
                          -  An unsupported address family with the
                             IO$_SETMODE subfunction was specified.
                             Instead, specify the TCPIP$C_AF_INET or
                             TCPIP$C_UNSPEC address family.
                          -  An unsupported address family for a
                             remote INET address with the IO$_ACCESS
                             or IO$_WRITEVBLK function was specified.
                             Instead, specify the TCPIP$C_AF_INET
                             address family.
                          -  An unsupported address family for the
                             local INET address with the IO$_SETMODE
                             function was specified. Instead, specify
                             the TCPIP$C_AF_INET address family.
                          -  An unsupported address family for the
                             INET address of the routing module was
                             specified. Instead, specify the TCPIP$C_
                             AF_INET address family.
    SS$_SHUT           The local or remote node is no longer
                       accepting connections.

  8 - IO$_SETMODE|IO$M_OUTBAND

    The IO$_SETMODE|IO$M_OUTBAND function/modifier combination
    requests that the asynchronous system trap (AST) for an out-
    of-band (OOB) character be delivered to the requesting process.
    This is to be done only when an OOB character is received on the
    socket and there is no waiting read request. The socket must be a
    TCP (stream) socket.
    The Enable OOB character AST function allows an Attention AST
    to be delivered to the requesting process only once. After the
    AST occurs, the function must explicitly reenable AST delivery
    before a new AST can be delivered. This function is subject to
    AST quotas.

 8.1 - Arguments

 p1
    OpenVMS usage:ast_procedure
    type:         procedure value
    access:       call without stack unwinding
    mechanism:    by reference
    To enable the AST, the p1 argument is the address of the OOB
    character AST routine. To disable the AST, p1 equals 0.
 p2
    OpenVMS usage:user_arg
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    AST parameter to be delivered to the AST routine specified by the
    p1 argument.
 p3
    OpenVMS usage:access_mode
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    Access mode to deliver the AST.

 8.2 - Condition Values Returned

    SS$_NORMAL         The service completed successfully.
    SS$_ABORT          Programming, INET management, or hardware
                       error.
    SS$_ACCVIO         Programming error. An attempt to access an
                       invalid memory location or buffer occurred.
    SS$_BADPARAM       Programming error. A $QIO service with an
                       invalid parameter occurred for one of the
                       following reasons:
                       o  An attempt to execute an IO$_SETMODE
                          function (all subfunctions, except socket
                          creation) without specifying a device
                          socket. Instead, create a device socket
                          by issuing a $QIO with the IO$_SETMODE
                          function and the proper parameters.
                       o  A socket option was specified incorrectly.
    SS$_DEVACTIVE      INET management error. An attempt to change
                       the static INET parameters occurred. If new
                       parameters are needed, shut down the internet,
                       reset the static parameters, and issue the
                       START COMMUNICATION command.
    SS$_DEVINTACT      INET management error. The driver was not
                       started. Issue a START COMMUNICATION command
                       before issuing $QIO functions.
    SS$_DEVNOTMOUNT    INET management error. The INET startup
                       procedure executed incorrectly. The driver was
                       loaded, but the INET_ACP was not activated.
                       Execute the INET startup procedure again.
    SS$_DUPLNAM        Programming error. An attempt to bind a port
                       that is already in use occurred. An attempt to
                       bind the socket to an address and port failed.
    SS$_EXQUOTA        Programming or INET management error occurred
                       because of one of the following reasons:
                       o  An attempt to create a new socket with the
                          IO$_SETMODE function failed because the
                          maximum number of sockets was exceeded.
                          Increase the maximum number of sockets
                          (INET parameter).
                       o  The number of sockets specified with the
                          IO$_SETMODE (listen) exceeds the maximum
                          number of sockets. Increase the maximum
                          number of sockets (INET parameter), or
                          reduce the listen parameter (the number
                          of sockets that the listener socket can
                          create).
    SS$_FILALRACC      Programming error. INET address is already
                       in use. An attempt to bind the socket to an
                       address and port failed.
    SS$_INSFMEM        Programming or system management error: Not
                       enough resources to allocate new socket.
    SS$_ILLCNTRFUNC    Programming error. Operation is not supported
                       because of one of the following reasons:
                       o  Invalid IO$_SETMODE (IOCTL) function was
                          used for the interface. The interface does
                          not have an IOCTL routine.
                       o  An attempt to perform an IO$_SETMODE
                          (IOCTL) function that required a socket,
                          but the device did not have one. Create a
                          socket and issue the IOCTL function.
    SS$_IVADDR         Programming error. The specified INET address
                       is not in the system, and an invalid port
                       number or an invalid INET address combination
                       was specified with an IO$_SETMODE function (a
                       bind) for one of the following reasons:
                       o  An attempt to bind the address failed
                          because the INET address is not in the
                          system and port zero and INET address zero
                          are not allowed.
                       o  An attempt to make a permanent entry in an
                          ARP table that was full failed.
                       o  An attempt was made to bind an IP socket
                          (raw IP) when there are no interfaces
                          defined in the system.
                       o  An attempt was made to bind an IP socket
                          (raw IP) to a null INET address.
    SS$_IVBUFLEN       Programming error. The socket option buffer
                       has an invalid size.
    SS$_NOLICENSE      Programming or system management error. TCP/IP
                       Services not present.
    SS$_NOOPER         Programming or INET management error. An
                       attempt was made to execute an I/O function
                       that needs the OPER privilege.
    SS$_NOPRIV         Programming or INET management error. Not
                       enough privileges for the attempted operation
                       for one of the following reasons:
                       o  Broadcasting an IP datagram was denied
                          because the process does not have a system
                          UIC or SYSPRV, BYPASS, or OPER privilege.
                       o  An attempt was made to use a reserved port
                          number lower than 1024.
                       o  An operation accesses only processes that
                          have a system UIC or SYSPRV or BYPASS
                          privilege.
                       o  Raw IP protocol can be used only on
                          privileged sockets. The process must have a
                          SYSPRV or BYPASS privilege.
    SS$_NOSUCHDEV      Programming error or INET management error.
                       An INET address is not in the ARP table. An
                       attempt to show or delete an ARP table entry
                       failed.
    SS$_NOSUCHNODE     Programming or INET management error. An
                       attempt to delete a route from the routing
                       table failed because a route entry was not
                       found.
    SS$_PROTOCOL       Programming error because of one of the
                       following reasons:
                       o  The protocol type specified at socket
                          creation is not valid.
                       o  The protocol is not supported.
                       o  The protocol type specified is not found
                          in the internal tables and therefore is an
                          invalid type.
                       o  The address family is not supported for one
                          of the following reasons:
                          -  The address family specified with an
                             IO$_SETMODE function (IOCTL subfunction)
                             is not supported. The address family
                             should be the TCPIP$C_AF_INET or
                             TCPIP$C_UNSPEC address family.
                          -  The address family of the local INET
                             address specified with an IO$_SETMODE
                             (bind) function is not supported. The
                             address family should be the TCPIP$C_AF_
                             INET address family.
                          -  The address family of the INET address
                             specified in a request to the routing
                             module is not supported. The address
                             family should be the TCPIP$C_AF_INET
                             address family.
    SS$_SHUT           The local or remote node is no longer
                       accepting connections.

  9 - IO$_SETMODE|IO$M_READATTN

    The IO$_SETMODE|IO$M_READATTN function/modifier combination
    requests that an Attention AST be delivered to the requesting
    process when a data packet is received on the socket and there is
    no waiting read request.
    The Enable Read Attention AST function enables an Attention AST
    to be delivered to the requesting process only once. After the
    AST occurs, the function must explicitly reenable AST delivery
    before the AST can occur again. The function is subject to AST
    quotas.
    Consider the following when using IO$M_READATTN:
    o  There is a one-to-one correspondence between the number of
       times you enable an Attention AST and the number of times the
       AST is delivered. For example, for each enabled AST, one AST
       is delivered. If you enable an Attention AST several times,
       several ASTs are delivered for one event when an event occurs.
    o  If an out-of-band (OOB) Attention AST is enabled, the OOB AST
       is delivered, regardless of the following:
       -  An enabled Read Attention AST
       -  The TCPIP$C_OOBINLINE socket option
       -  A READ $QIO waiting for completion on the socket
    If the TCPIP$C_OOBINLINE option is set, then a waiting READ
    $QIO is completed and the OOB character is returned in the data
    stream.
    o  If both an OOB AST and a Read Attention AST are enabled, only
       the OOB AST is delivered when an OOB character is received.
    o  If a Read Attention AST is enabled and the TCPIP$C_OOBINLINE
       socket option is set, a waiting READ $QIO completes and the
       OOB character is returned in the data stream.
    o  If a Read Attention AST is enabled and the TCPIP$C_OOBINLINE
       socket option is not set (clear), the Read Attention AST
       is delivered when an OOB character is received, regardless
       of whether a READ $QIO is waiting for completion. In this
       case, the OOB character is not returned in the data stream.
       Therefore, if the OOB character is the only character
       received, the READ $QIO does not complete.

 9.1 - Arguments

 p1
    OpenVMS usage:ast_procedure
    type:         procedure value
    access:       call without stack unwinding
    mechanism:    by reference
    To enable the AST, the p1 argument is the address of the Read
    Attention AST routine. To disable the AST, set p1 to 0.
 p2
    OpenVMS usage:user_arg
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    AST parameter to be delivered to the AST routine.
 p3
    OpenVMS usage:access_mode
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    Access mode to deliver the AST.

 9.2 - Condition Values Returned

    SS$_ABORT          Programming, INET management, or hardware
                       error. The route entry already exists, so
                       the attempt to add a route entry using the
                       IO$_SETMODE function failed.
    SS$_ACCVIO         Programming error. An attempt to access an
                       invalid memory location or buffer occurred.
    SS$_BADPARAM       Programming error. The parameter specified
                       for a $QIO function was invalid for one of the
                       following reasons:
                       o  An attempt to execute the IO$_SETMODE
                          subfunctions without specifying a device
                          socket occurred. Instead, create a device
                          socket by issuing a $QIO with the IO$_
                          SETMODE function and the proper parameters.
                       o  A socket option was specified incorrectly.
    SS$_DEVACTIVE      INET management error. An attempt to change
                       the static INET parameter was unsuccessful.
                       If you need new parameters, shut down the
                       internet, reset the static parameters, and
                       issue the START COMMUNICATION command.
    SS$_DEVINTACT      INET management error. The driver was not
                       started. Issue a START COMMUNICATION command
                       before issuing $QIO functions.
    SS$_DEVNOTMOUNT    INET management error. TCP/IP Services
                       improperly executed the startup procedure. The
                       driver was loaded, but the INET_ACP was not
                       activated. Execute the INET startup procedure
                       again.
    SS$_DUPLNAM        Programming error. An attempt to bind a port
                       already in use occurred so the operation
                       to bind the socket to the address and port
                       failed.
    SS$_EXQUOTA        Programming or INET management error. The
                       quota for the valid number of sockets caused
                       an error for one of the following reasons:
                       o  An attempt to exceed the maximum number
                          of sockets by creating new socket with the
                          IO$_SETMODE function occurred. Increase the
                          maximum number of allowable sockets (INET
                          parameter) before creating more sockets.
                       o  The number of sockets specified with the
                          IO$_SETMODE function exceeds the maximum
                          number of sockets allowed. Increase the
                          maximum number of sockets (INET parameter)
                          or reduce the number of sockets that
                          the listener socket can create (listen
                          parameter).
    SS$_FILALRACC      Programming error. An attempt to bind the
                       socket to an address that is already in use
                       occurred and the operation failed.
    SS$_INSFMEM        Programming or system management error. The
                       system does not have enough resources to
                       allocate new socket.
    SS$_ILLCNTRFUNC    Programming error. Operation is not supported.
                       o  Invalid IO$_SETMODE (IOCTL) function was
                          used for the interface. The interface does
                          not have an IOCTL routine.
                       o  An attempt was made to perform an IO$_
                          SETMODE (IOCTL) function that required
                          a socket, but the device did not have
                          one. Create a socket and issue the IOCTL
                          function.
    SS$_IVADDR         Programming error. The specified INET address
                       is not in the system, and an invalid port
                       number or an invalid INET address combination
                       was specified with an IO$_SETMODE function (a
                       bind).
                       o  An attempt to bind the address failed
                          because the INET address is not in the
                          system, port zero and INET address zero are
                          not allowed, or port zero is not allowed
                          when using an IO$_ACCESS or IO$_WRITEVBLK
                          function.
                       o  An attempt to make a permanent entry in the
                          ARP table failed because of lack of space.
                          Too many permanent entries.
                       o  An attempt was made to bind an IP socket
                          (raw IP) when there are no interfaces
                          defined in the system.
                       o  An attempt was made to bind an IP socket
                          (raw IP) to a null INET address.
    SS$_IVBUFLEN       Programming error. The socket option buffer
                       has an invalid size.
    SS$_NOLICENSE      Programming or system management error. TCP/IP
                       Services not present.
    SS$_NOOPER         Programming or INET management error. An
                       attempt was made to execute an I/O function
                       that needs the OPER privilege.
    SS$_NOPRIV         Programming or INET management error. Not
                       enough privileges for the attempted operation.
                       o  Broadcasting an IP datagram was denied
                          because the process does not have a system
                          UIC or SYSPRV, BYPASS, or OPER privilege.
                       o  An attempt was made to use a reserved port
                          number lower than 1024.
                       o  An operation accesses only processes that
                          have a system UIC or SYSPRV, or BYPASS
                          privilege.
                       o  Raw IP protocol can be used only on
                          privileged sockets. The process must have a
                          SYSPRV or BYPASS privilege.
    SS$_NOSUCHDEV      Programming error or INET management error.
                       An INET address is not in the ARP table. An
                       attempt to show or delete an ARP table entry
                       failed.
    SS$_NOSUCHNODE     Programming error or INET management error.
                       An attempt to delete a route from the routing
                       table failed because a route entry was not
                       found.
    SS$_PROTOCOL       Programming error.
                       o  The protocol type specified at socket
                          creation is not valid.
                       o  The protocol is not supported.
                       o  The protocol type specified is not found in
                          the internal tables. It is an invalid type.
                       o  The address family is not supported:
                          -  The address family specified with an
                             IO$_SETMODE function (IOCTL subfunction)
                             is not supported. The address family
                             should be the TCPIP$C_AF_INET or
                             TCPIP$C_UNSPEC address family.
                          -  The address family of the remote INET
                             address specified with an IO$_ACCESS or
                             IO$_WRITEVBLK function is not supported
                             (UDP/IP or TCP/IP). The address family
                             should be the TCPIP$C_AF_INET address
                             family.
                          -  The address family of the local INET
                             address specified with an IO$_SETMODE
                             (bind) function is not supported. The
                             address family should be the TCPIP$C_AF_
                             INET address family.
                          -  The address family of the INET address
                             that is specified in a request to the
                             routing module is not supported. The
                             address family should be the TCPIP$C_AF_
                             INET address family.
    SS$_SHUT           The local or remote node is no longer
                       accepting connections.

  10 - IO$_SETMODE|IO$M_WRTATTN

    The IO$_SETMODE|IO$M_WRTATTN function/modifier combination (IO$M_
    WRTATTN is Enable Write Attention AST) requests that an Attention
    AST be delivered to the requesting process when a data packet can
    be queued to the socket. For TCP sockets, this occurs when space
    becomes available in the TCP transmit queue.
    The Enable Write Attention AST function enables an Attention AST
    to be delivered to the requesting process only once. After the
    AST occurs, the function must explicitly reenable AST delivery
    before the AST can occur again. The function is subject to AST
    quotas.
    There is a one-to-one correspondence between the number of
    times you enable an Attention AST and the number of times the
    AST is delivered. For example, for each enabled AST, one AST is
    delivered. If you enable an Attention AST several times, several
    ASTs are delivered for one event when the event occurs.
    You can use the management command SHOW DEVICE_SOCKET to display
    information about the socket's characteristics, options, and
    state.

 10.1 - Arguments

 p1
    OpenVMS usage:ast_procedure
    type:         procedure value
    access:       call without stack unwinding
    mechanism:    by reference
    To enable the AST, the p1 argument is the address of the Write
    Attention AST routine. To disable the AST, p1 is set to 0.
 p2
    OpenVMS usage:user_arg
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    AST parameter to be delivered to the AST routine.
 p3
    OpenVMS usage:access_mode
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    Access mode to deliver the AST.

 10.2 - Condition Values Returned

    SS$_ABORT          Programming error, INET management error,
                       or hardware error. The route specified with
                       the IO$_SETMODE function already exists.
                       Therefore, the operation failed.
    SS$_ACCVIO         Programming error. An attempt to access an
                       invalid memory location or buffer occurred.
    SS$_BADPARAM       Programming error. The parameter specified for
                       the $QIO I/O function was invalid for one of
                       the following reasons:
                       o  An attempt to execute the IO$_SETMODE
                          functions without specifying a device
                          socket occurred. Instead, create a device
                          socket by issuing a $QIO with the IO$_
                          SETMODE function and the proper parameters.
                       o  A socket option was specified incorrectly.
    SS$_DEVACTIVE      INET management error. You attempted to change
                       the static INET parameters. If you need new
                       parameters, shut down the internet, reset
                       the static parameters, and issue the START
                       COMMUNICATION command.
    SS$_DEVINTACT      INET management error. The driver is not
                       started. Issue a START COMMUNICATION command
                       before issuing $QIO functions.
    SS$_DEVNOTMOUNT    INET management error. The INET startup
                       procedure was improperly executed. The
                       driver was loaded, but the INET_ACP was not
                       activated. Execute the INET startup procedure
                       again.
    SS$_DUPLNAM        Programming error. Port that is being bound is
                       already in use. An attempt to bind the socket
                       to an address and port failed.
    SS$_EXQUOTA        Programming or INET management error.
                       o  An attempt to create a new socket with the
                          IO$_SETMODE function and it failed because
                          the maximum number of sockets was exceeded.
                          Increase the maximum number of sockets
                          (INET parameter), and then create a new
                          socket.
                       o  The number of sockets specified with the
                          IO$_SETMODE function exceeds the allowable
                          maximum number of sockets. Increase the
                          maximum number of sockets (INET parameter),
                          or reduce the number of sockets that
                          the listener socket can create (listen
                          parameter).
    SS$_FILALRACC      Programming error. Because the INET address is
                       already in use, an attempt to bind the socket
                       to an address and port failed.
    SS$_INSFMEM        Programming or system management error. There
                       are not enough resources to allocate a new
                       socket.
    SS$_ILLCNTRFUNC    Programming error. The operation is
                       unsupported for one of the following reasons:
                       o  An invalid IO$_SETMODE function for the
                          interface was specified. The interface does
                          not have an IOCTL routine.
                       o  An attempt to execute an IO$_SETMODE
                          function that required a socket, but the
                          device did not have one. Instead, create a
                          socket and issue the function.
    SS$_IVADDR         Programming error. An invalid port number and
                       INET address combination was specified with
                       the IO$_SETMODE bind function. This caused
                       the operation to fail for one of the following
                       reasons:
                       o  An illegal combination of port zero and
                          INET address zero was specified.
                       o  An attempt to make a permanent entry in
                          the ARP table occurred, and the operation
                          failed because of lack of space. There are
                          too many permanent entries.
                       o  An attempt to bind a raw IP socket occurred
                          when there were no interfaces defined in
                          the system.
                       o  An attempt to bind a raw IP socket to a
                          null INET address occurred.
    SS$_IVBUFLEN       Programming error. An invalid size was
                       specified for the socket option buffer.
    SS$_NOLICENSE      Programming or system management error. There
                       is no TCP/IP Services license present.
    SS$_NOOPER         Programming or INET management error. An
                       attempt to execute an I/O function that needs
                       the OPER privilege occurred.
    SS$_NOPRIV         Programming or INET management error. The
                       operation failed for one of the following
                       reasons:
                       o  An attempt to broadcast an IP datagram for
                          a process without having a system UIC or
                          SYSPRV, BYPASS, or OPER privilege.
                       o  An attempt to use a reserved port number
                          lower than 1024 occurred.
                       o  An attempt to access a process without
                          having a system UIC or SYSPRV, or BYPASS
                          privilege occurred.
                       o  An attempt to use raw IP on a socket that
                          is not a privileged socket occurred. To
                          do this, the process must have SYSPRV or
                          BYPASS privilege.
    SS$_NOSUCHDEV      Programming error or INET management error. An
                       attempt to show or delete an entry in the
                       ARP table occurred. However, because the
                       INET address was not in the ARP table, the
                       operation failed.
    SS$_NOSUCHNODE     Programming error or INET management error.
                       An attempt to delete a route from the routing
                       information table (RIT) occurred. However,
                       because the route was not found in the RIT,
                       the operation failed.
    SS$_PROTOCOL       Programming error.
                       o  An invalid protocol type was specified when
                          creating a socket.
                       o  An unsupported protocol was specified.
                       o  An unsupported protocol type was specified
                          because it is not found in the internal
                          tables.
                       o  An unsupported address family was specified
                          for one of the following reasons:
                             -  An invalid address family was
                                specified with an IO$_SETMODE
                                subfunction. Instead, specify the
                                TCPIP$C_AF_INET or TCPIP$C_UNSPEC
                                address family.
                             -  An address family of the remote INET
                                address for a datagram or stream
                                socket was specified with an IO$_
                                ACCESS or IO$_WRITEVBLK function.
                                Instead, specify the TCPIP$C_AF_INET
                                address family.
                             -  An invalid address family of the
                                local INET address was specified
                                with an IO$_SETMODE bind function.
                                Instead, specify the TCPIP$C_AF_INET
                                address family.
                             -  You made a request to the routing
                                module by specifying the address
                                family of the INET address. Instead,
                                specify the TCPIP$C_AF_INET address
                                family.
    SS$_SHUT           The local or remote node is no longer
                       accepting connections.

  11 - IO$_WRITEVBLK

    The IO$_WRITEVBLK function transmits data from the specified
    user buffers to an internet host. Use both p1 and p2 arguments
    to specify a single user buffer. Use the p5 argument to specify
    multiple buffers.
    For connection-oriented protocols, such as TCP, if the socket
    transmit buffer is full, the IO$_WRITEVBLK function is blocked
    until the socket transmit buffer has room for the user data.
    For connectless-oriented protocols, such as UDP and raw IP, the
    user data is transmitted in one datagram. If the user data is
    greater than the socket's transmit quota, the error code (SS$_
    TOOMUCHDATA) is returned.
    Related Functions
    The equivalent Sockets API functions are send(), sendto(),
    sendmsg(), and write().

 11.1 - Arguments

 p1
    OpenVMS usage:buffer
    type:         vector byte (unsigned)
    access:       read only
    mechanism:    by 32- or 64-bit reference (Alpha)
                  by 32-bit reference (VAX)
    The 32- or 64-bit address (on Alpha systems) or the 32-bit
    address (on VAX systems) of the buffer containing the data to
    be transmitted. The length of this buffer is specified by the p2
    argument.
 p2
    OpenVMS usage:buffer_length
    type:         quadword unsigned (Alpha); longword unsigned (VAX)
    access:       read only
    mechanism:    by 64-bit value (Alpha)
                  by 32-bit value (VAX)
    The length (in bytes) of the buffer containing data to be
    transmitted. The address of this buffer is specified by the p1
    argument.
 p3
    OpenVMS usage:socket_name
    type:         vector byte (unsigned)
    access:       read only
    mechanism:    by item_list_2 descriptor
    The remote port number and internet address of the message
    destination. The p3 argument is the address of an item_list_2
    descriptor pointing to the socket address structure containing
    the remote port number and internet address.
 p4
    OpenVMS usage:mask_longword
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    Longword of flags to specify attributes for this write operation.
    The following table lists the available write flags:
    Write Flag            Description
    TCPIP$C_MSG_OOB       Writes an out-of-band (OOB) byte.
    TCPIP$C_MSG_          Sends message directly without routing.
    DONTROUTE
    TCPIP$C_MSG_NBIO      Completes the I/O operation and returns
                          an error if a condition arises that would
                          cause the I/O operation to be blocked.
                          (Similar to using IO$M_NOWAIT.)
 p5
    OpenVMS usage:buffer_list
    type:         vector byte (unsigned)
    access:       read only
    mechanism:    by 32- or 64-bit descriptor-fixed-length descriptor
                  (Alpha)
                  by 32-bit descriptor-fixed-length descriptor (VAX)
    Input buffer list describing one or more buffers containing the
    data to be transmitted. The p5 argument is the 32- or 64-bit
    address (on Alpha systems) or the 32-bit address (on VAX systems)
    of a descriptor pointing to a input buffer list. Buffers are
    transmitted in the order specified by the input buffer list. The
    transfer-length value returned in the I/O status block is the
    total number of bytes transferred from all buffers.
    If you use the p1 and p2 arguments, do not use the p5 argument;
    they are mutually exclusive.

 11.2 - Function Modifiers

    IO$M_EXTEND        Allows the use of extended modifiers with BSD
                       Version 4.4. Valid only for datagram sockets
                       (UDP or raw IP); ignored for TCP.
    IO$M_INTERRUPT     Sends an OOB message.
    IO$M_NOWAIT        Regardless of a $QIO or $QIOW, if the system
                       detects a condition that would cause the
                       operation to block, the system completes the
                       I/O operation and returns the SS$_SUSPENDED
                       status code.
                       When using this function modified, always
                       check the message length in the IOSB to ensure
                       that all data is transferred. IO$_WRITEVBLK
                       returns a success status even if data is only
                       partially transferred.

 11.3 - Condition Values Returned

    SS$_ABORT          Programming error, INET management error, or
                       hardware error. The execution of the I/O was
                       aborted.
    SS$_ACCVIO         Programming error. An attempt was made to
                       access an invalid memory location or buffer.
    SS$_BADPARAM       Programming error. A $QIO I/O function was
                       specified using an invalid parameter.
                       o  An attempt was made to execute an
                          IO$_WRITEVBLK function without specifying a
                          device socket. First create a device socket
                          by issuing an IO$_SETMODE function and the
                          proper arguments.
                       o  An attempt was made to issue an
                          IO$_WRITEVBLK function that did not specify
                          a correct buffer address (p1 or p5 is
                          null).
                       o  An attempt was made to issue an IO$_
                          WRITEVBLK that specifies an invalid
                          vectored buffer (p5 specifies an invalid
                          address descriptor).
    SS$_CANCEL         The I/O operation was canceled by the $CANCEL
                       system service.
    SS$_DEVINTACT      The network driver was not started.
    SS$_DEVNOTMOUNT    The network driver is loaded, but the INETACP
                       in not currently available for use.
    SS$_EXQUOTA        Returned when process resource mode wait is
                       disabled. There is no internet request packet
                       (IRP) available for completing the request.
                       Increase the buffered I/O quota.
    SS$_FILALRACC      Programming error.
                       o  INET address is already in use. An attempt
                          was made to bind the socket to an address
                          but the port failed.
                       o  IP protocol (raw socket). An attempt was
                          made to specify a remote INET socket
                          address with an IO$_WRITEVBLK function,
                          while an INET address was already specified
                          with an IO$_ACCESS function.
                       o  UDP/IP protocol. An attempt was made to
                          specify a remote INET socket address with
                          an IO$_WRITEVBLK function, while an INET
                          address was already specified with the IO$_
                          ACCESS function.
    SS$_ILLCNTRFUNC    Programming error. Unsupported operation on
                       the protocol (IP, UDP/IP, TCP/IP).
    SS$_INSFMEM        INET management or programming error returned
                       when process resource mode wait is disabled.
                       Not enough system space for buffering user
                       data. A higher quota for socket buffer space
                       needs to be set, or the internet needs more
                       dynamic buffer space (number of dynamic
                       clusters should be increased).
    SS$_IVADDR         Programming error. The specified INET address
                       is not in the system, and an invalid port
                       number or an INET address combination was
                       specified with an IO$_WRITEVBLK operation.
                       o  An attempt to bind the socket failed
                          because the INET address is not in the
                          system, port number zero and INET address
                          zero are not allowed, or port zero is not
                          allowed with an IO$_ACCESS or IO$_WRITEVBLK
                          function.
                       o  An attempt to get an interface INET
                          address, broadcast mask, or network mask
                          failed.
                       o  A send request was made on a datagram-
                          oriented protocol, but the destination
                          address is unknown or not specified.
    SS$_IVBUFLEN       Programming error.
                       o  The size of the buffer for an I/O function
                          is insufficient.
                       o  An attempt was made to issue an
                          IO$_WRITEVBLK function that specifies a
                          correct buffer address (p1 valid) but does
                          not specify a buffer length (p2 is null).
    SS$_LINKDISCON     Notification. Connection completion return
                       code. The virtual circuit (TCP/IP) was closed
                       at the initiative of the peer. The application
                       must stop sending data and must either shut
                       down or close the socket.
    SS$_PROTOCOL       Programming error. The address family of
                       the remote INET address specified with an
                       IO$_WRITEVBLK function is not supported
                       (UDP/IP or TCP/IP). The address family should
                       be the TCPIP$C_AF_INET address family.
    SS$_NOLINKS        Programming error. The socket was not
                       connected (TCP/IP), or an INET port and
                       address were not specified with an IO$_ACCESS
                       (UDP/IP or IP).
                       o  An IO$_WRITEVBLK with no remote INET socket
                          address was issued on a socket that was not
                          the object of an IO$_ACCESS function (raw
                          IP).
                       o  An IO$_WRITEVBLK with no remote INET socket
                          address was issued on a socket that was
                          not the object of an IO$_ACCESS function
                          (UDP/IP).
                       o  An attempt was made to disconnect a socket
                          that is not connected, or an attempt was
                          made to issue an IO$_WRITEVBLK function on
                          an unconnected socket (TCP/IP).
    SS$_SHUT           The local or remote node is no longer
                       accepting connections.
    SS$_SUSPENDED      The system detected a condition that might
                       cause the operation to block.
    SS$_TIMEOUT        Programming error, INET management error, or
                       hardware error.
                       o  A TCP/IP connection timed out after several
                          unsuccessful retransmissions.
                       o  On a TCP socket where KEEPALIVE is set,
                          the connection was idle for longer than
                          the timeout interval (The default is 10
                          minutes).
    SS$_TOOMUCHDATA    Programming or INET management error. The
                       message size was too large.
                       o  An IP packet that is broadcast cannot be
                          fragmented.
                       o  The Not Fragment IP flag was set and the IP
                          datagram was too large to be sent without
                          being fragmented.
                       o  Internal error. The length of the Ethernet
                          datagram does not allow enough space for
                          the minimum IP header.
                       o  The message to be sent on a UDP/IP or raw
                          IP socket is larger than the socket buffer
                          high water allows.
                       o  An attempt was made to send or receive
                          more than 16 buffers specified with the p5
                          argument.
    SS$_UNREACHABLE    Communication status. The remote host is
                       currently unreachable.
                       Hardware error. The data link adapter detected
                       an error and shut itself off. The TCP/IP
                       Services software is waiting for the adapter
                       to come back on line.
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