t_accept(3)                                                 t_accept(3)

  t_accept()

  NAME

    t_accept - accept a connection request

  SYNOPSIS

    #include 

    int t_accept(
        int fd,
        int resfd,
        const struct t_call *call)

  DESCRIPTION

    The following table provides an overview of the t_accept(3) function
    parameters.

    Parameters     Before call      After call

    fd             x                /

    resfd          x                /

    call->         addr.maxlen      =

    call->         addr.len         x

    call->         addr.buf         ? (?)

    call->         opt.maxlen       =

    call->         opt.len          x

    call->         opt.buf          ? (?)

    call->         udata.maxlen     =

    call->         udata.len        x

    call->         udata.buf        ? (?)

    call->         sequence         x

    The t_accept(3) function is issued by a transport user to accept a
    connection request. The parameter fd identifies the local transport
    endpoint where the connection indication arrived; resfd specifies the
    local transport endpoint where the connection is to be established, and
    call contains information required by the transport provider to complete
    the connection. The parameter call points to a t_call structure which
    contains the following members:

    struct netbuf addr;
    struct netbuf opt;
    struct netbuf udata;
    int sequence;

    In call, addr is the protocol address of the calling transport user, opt
    indicates any options associated with the connection, udata points to any
    user data to be returned to the caller, and sequence is the value returned
    by t_listen(3) that uniquely associates the response with a previously
    received connection indication. The address of the caller, addr can be
    null (length zero); where addr is not null, it can optionally be checked
    by X/Open Transport Interface (XTI).

    A transport user can accept a connection on either the same local
    transport endpoint as the one on which the connection indication arrived,
    or on a different local transport endpoint. Before the connection can be
    accepted on the same endpoint (resfd==fd), the user must have responded to
    any previous connection indications received on that transport endpoint
    (through t_accept(3) or t_snddis(3). Otherwise, t_accept(3) will fail and
    set t_errno to [TINDOUT].

    If a different transport endpoint is specified (resfd!=fd), the user might
    or might not choose to bind the endpoint before the t_accept(3) is issued.
    If the endpoint is not bound prior to the t_accept(3), the endpoint must
    be in the T_UNBND state before the t_accept(3) is issued, and the
    transport provider will automatically bind it to an address that is
    appropriate for the protocol concerned. If the transport user chooses to
    bind the endpoint, it must be bound to a protocol address with a qlen of
    zero and must be in the T_IDLE state before the t_accept(3) is issued.

    Responding endpoints should be supplied to t_accept(3) in the state
    T_UNBND.

    The call to t_accept(3) can fail with t_errno set to [TLOOK] if there are
    indications (for example, connect or disconnect) waiting to be received on
    endpoint fd. Applications should be prepared for such a failure.

    The udata argument enables the called transport user to send user data to
    the caller. The amount of user data must not exceed the limits supported
    by the transport provider as returned in the connect field of the info
    argument of t_open(3) or t_getinfo(3). If the len field of udata is zero,
    no data will be sent to the caller. All the maxlen fields are meaningless.

    When the user does not indicate any option (call->opt.len = 0) the
    connection will be accepted with the option values currently set for the
    responding endpoint, resfd.

  CAVEATS

    There might be transport provider-specific restrictions on address
    binding.

    Some transport providers do not differentiate between a connection
    indication and the connection itself. If the connection has already been
    established after a successful return of t_listen(3), t_accept(3) will
    assign the existing connection to the transport endpoint specified by
    resfd.

  VALID STATES

    fd: T_INCON
    resfd (fd!=resfd): T_IDLE, T_UNBND

  ERRORS

    On failure, t_errno is set to one of the following values:

    [TACCES]
        The user does not have permission to accept a connection on the
        responding transport endpoint or to use the specified options.

    [TBADADDR]
        The specified protocol address was in an incorrect format or contained
        illegal information.

    [TBADDATA]
        The amount of user data specified was not within the bounds allowed by
        the transport provider.

    [TBADF]
        The file descriptor fd or resfd does not refer to a transport
        endpoint.

    [TBADOPT]
        The specified options were in an incorrect format or contained illegal
        information.

    [TBADSEQ]
        Either an invalid sequence number was specified, or a valid sequence
        number was specified but the connection request was aborted by the
        peer. In the latter case, its T_DISCONNECT event will be received on
        the listening endpoint.

    [TINDOUT]
        The function was called with fd==resfd, but there are outstanding
        connection indications on the endpoint. Those other connection
        indications must be handled either by rejecting them through
        t_snddis(3) or accepting them on a different endpoint through
        t_accept(3).

    [TLOOK]
        An asynchronous event occurred on the transport endpoint referenced by
        fd and requires immediate attention.

    [TNOTSUPPORT]
        This function is not supported by the underlying transport provider.

    [TOUTSTATE]
        The communications endpoint referenced by fd or resfd is not in one of
        the states in which a call to this function is valid.

    [TPROTO]
        This error indicates that a communication problem has been detected
        between XTI and the transport provider for which there is no other
        suitable XTI error (t_errno).

    [TPROVMISMATCH]
        The file descriptors fd and resfd do not refer to the same transport
        provider.

    [TRESADDR]
        This transport provider requires both fd and resfd to be bound to the
        same address; this error appears if they are not bound to the same
        address.

    [TRESQLEN]
        The endpoint referenced by resfd (where resfd != fd) was bound to a
        protocol address with a qlen that is greater than zero.

    [TSYSERR]
        A system error occurred during the execution of this function.

  RETURN VALUE

    Upon successful completion, a value of 0 is returned. Otherwise, a value
    of -1 is returned and t_errno is set to indicate an error.

  SEE ALSO

    t_connect(3)

    t_getstate(3)

    t_listen(3)

    t_open(3)

    t_optmgmt(3)

    t_rcvconnect(3)

  USAGE NOTES

    The t_accept function is not thread safe.

    The t_accept function is not async-signal safe.