T_BIND(3NSL) Networking Services Library Functions T_BIND(3NSL)

NAME


t_bind - bind an address to a tansport endpoint

SYNOPSIS


Network Services Library (libnsl, -lnsl)
#include <xti.h>

int
t_bind(int fd, const struct t_bind *req, stuct t_bind *ret);

DESCRIPTION


This routine is part of the XTI interfaces that evolved from the TLI
interfaces. XTI represents the future evolution of these interfaces.
However, TLI interfaces are supported for compatibility. When using a TLI
routine that has the same name as an XTI routine, the <tiuser.h> header
file must be used. Refer to the TLI COMPATIBILITY section for a
description of differences between the two interfaces.

This function associates a protocol address with the transport endpoint
specified by fd and activates that transport endpoint. In connection mode,
the transport provider may begin enqueuing incoming connect indications, or
servicing a connection request on the transport endpoint. In
connectionless-mode, the transport user may send or receive data units
through the transport endpoint.

The req and ret arguments point to a t_bind structure containing the
following members:

struct netbuf addr;
unsigned qlen;

The addr field of the t_bind structure specifies a protocol address, and
the qlen field is used to indicate the maximum number of outstanding
connection indications.

The parameter req is used to request that an address, represented by the
netbuf structure, be bound to the given transport endpoint. The parameter
len specifies the number of bytes in the address, and buf points to the
address buffer. For tcp(7P) and udp(7P) transports, buf points to a
sockaddr(3SOCKET) buffer -- either struct sockaddr_in or struct
sockaddr_in6 (depending on if IPv4 or IPv6 is being used). The parameter
maxlen has no meaning for the req argument.

On return, ret contains an encoding for the address that the transport
provider actually bound to the transport endpoint; if an address was
specified in req, this will be an encoding of the same address. In ret,
the user specifies maxlen, which is the maximum size of the address buffer,
and buf which points to the buffer where the address is to be placed. On
return, len specifies the number of bytes in the bound address, and buf
points to the bound address. If maxlen equals zero, no address is
returned. If maxlen is greater than zero and less than the length of the
address, t_bind() fails with t_errno set to TBUFOVFLW.

If the requested address is not available, t_bind() will return -1 with
t_errno set as appropriate. If no address is specified in req (the len
field of addr in req is zero or req is NULL), the transport provider will
assign an appropriate address to be bound, and will return that address in
the addr field of ret. If the transport provider could not allocate an
address, t_bind() will fail with t_errno set to TNOADDR.

The parameter req may be a null pointer if the user does not wish to
specify an address to be bound. Here, the value of qlen is assumed to be
zero, and the transport provider will assign an address to the transport
endpoint. Similarly, ret may be a null pointer if the user does not care
what address was bound by the provider and is not interested in the
negotiated value of qlen. It is valid to set req and ret to the null
pointer for the same call, in which case the provider chooses the address
to bind to the transport endpoint and does not return that information to
the user.

The qlen field has meaning only when initializing a connection-mode
service. It specifies the number of outstanding connection indications
that the transport provider should support for the given transport
endpoint. An outstanding connection indication is one that has been passed
to the transport user by the transport provider but which has not been
accepted or rejected. A value of qlen greater than zero is only meaningful
when issued by a passive transport user that expects other users to call
it. The value of qlen will be negotiated by the transport provider and may
be changed if the transport provider cannot support the specified number of
outstanding connection indications. However, this value of qlen will never
be negotiated from a requested value greater than zero to zero. This is a
requirement on transport providers; see WARNINGS below. On return, the
qlen field in ret will contain the negotiated value.

If fd refers to a connection-mode service, this function allows more than
one transport endpoint to be bound to the same protocol address. It is not
possible to bind more than one protocol address to the same transport
endpoint. However, the transport provider must also support this
capability. If a user binds more than one transport endpoint to the same
protocol address, only one endpoint can be used to listen for connection
indications associated with that protocol address. In other words, only
one t_bind() for a given protocol address may specify a value of qlen
greater than zero. In this way, the transport provider can identify which
transport endpoint should be notified of an incoming connection indication.
If a user attempts to bind a protocol address to a second transport
endpoint with a value of qlen greater than zero, t_bind() will return -1
and set t_errno to TADDRBUSY. When a user accepts a connection on the
transport endpoint that is being used as the listening endpoint, the bound
protocol address will be found to be busy for the duration of the
connection, until a t_unbind(3NSL) or t_close(3NSL) call has been issued.
No other transport endpoints may be bound for listening on that same
protocol address while that initial listening endpoint is active (in the
data transfer phase or in the T_IDLE state). This will prevent more than
one transport endpoint bound to the same protocol address from accepting
connection indications.

If fd refers to connectionless mode service, this function allows for more
than one transport endpoint to be associated with a protocol address, where
the underlying transport provider supports this capability (often in
conjunction with value of a protocol-specific option). If a user attempts
to bind a second transport endpoint to an already bound protocol address
when such capability is not supported for a transport provider, t_bind()
will return -1 and set t_errno to TADDRBUSY.

RETURN VALUES


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.

VALID STATES


T_UNBND

ERRORS


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

TACCES The user does not have permission to use the specified
address.

TADDRBUSY The requested address is in use.

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

TBADF The specified file descriptor does not refer to a
transport endpoint.

TBUFOVFLW The number of bytes allowed for an incoming argument ~
maxlen is greater than 0 but not sufficient to store the
value of that argument. The provider's state will
change to T_IDLE and the information to be returned in
ret will be discarded.

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

TNOADDR The transport provider could not allocate an address.

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).

TSYSERR A system error has occurred during execution of this
function.

TLI COMPATIBILITY


The XTI and TLI interface definitions have common names but use different
header files. This, and other semantic differences between the two
interfaces are described in the subsections below.

Interface Header


The XTI interfaces use the header file, <xti.h>. TLI interfaces should not
use this header. They should use the header: <tiuser.h>

Address Bound


The user can compare the addresses in req and ret to determine whether the
transport provider bound the transport endpoint to a different address than
that requested.

Error Description Values


The t_errno values TPROTO and TADDRBUSY can be set by the XTI interface but
cannot be set by the TLI interface.

A t_errno value that this routine can return under different circumstances
than its XTI counterpart is TBUFOVFLW. It can be returned even when the
maxlen field of the corresponding buffer has been set to zero.

MT-LEVEL
Safe

SEE ALSO


t_accept(3NSL), t_alloc(3NSL), t_close(3NSL), t_connect(3NSL),
t_unbind(3NSL), sockaddr(3SOCKET), attributes(5)

WARNINGS


The requirement that the value of qlen never be negotiated from a requested
value greater than zero to zero implies that transport providers, rather
than the XTI implementation itself, accept this restriction.

An implementation need not allow an application explicitly to bind more
than one communications endpoint to a single protocol address, while
permitting more than one connection to be accepted to the same protocol
address. That means that although an attempt to bind a communications
endpoint to some address with qlen=0 might be rejected with TADDRBUSY, the
user may nevertheless use this (unbound) endpoint as a responding endpoint
in a call to t_accept(3NSL). To become independent of such implementation
differences, the user should supply unbound responding endpoints to
t_accept(3NSL).

The local address bound to an endpoint may change as result of a
t_accept(3NSL) or t_connect(3NSL) call. Such changes are not necessarily
reversed when the connection is released.

illumos September 28, 2017 illumos