t_connect(3N) UNIX System V(Networking Support Utilities) t_connect(3N)
NAME
tconnect - establish a connection with another transport user
SYNOPSIS
#include <tiuser.h>
int tconnect(fd, sndcall, rcvcall)
int fd;
struct tcall *sndcall;
struct tcall *rcvcall;
DESCRIPTION
This function enables a transport user to request a connection to the
specified destination transport user. fd identifies the local transport
endpoint where communication will be established, while sndcall and
rcvcall point to a tcall structure that contains the following members:
struct netbuf addr;
struct netbuf opt;
struct netbuf udata;
int sequence;
sndcall specifies information needed by the transport provider to
establish a connection and rcvcall specifies information that is
associated with the newly established connection.
netbuf is described in intro(3N). In sndcall, addr specifies the
protocol address of the destination transport user, opt presents any
protocol-specific information that might be needed by the transport
provider, udata points to optional user data that may be passed to the
destination transport user during connection establishment, and sequence
has no meaning for this function.
On return in rcvcall, addr returns the protocol address associated with
the responding transport endpoint, opt presents any protocol-specific
information associated with the connection, udata points to optional user
data that may be returned by the destination transport user during
connection establishment, and sequence has no meaning for this function.
The opt argument implies no structure on the options that may be passed
to the transport provider. The transport provider is free to specify the
structure of any options passed to it. These options are specific to the
underlying protocol of the transport provider. The user may choose not
to negotiate protocol options by setting the len field of opt to zero.
In this case, the provider may use default options.
The udata argument enables the caller to pass user data to the
destination transport user and receive user data from the destination
user during connection establishment. However, 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 topen or
tgetinfo. If the len [see netbuf in intro(3N)] field of udata is zero
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t_connect(3N) UNIX System V(Networking Support Utilities) t_connect(3N)
in sndcall, no data will be sent to the destination transport user.
On return, the addr, opt, and udata fields of rcvcall will be updated to
reflect values associated with the connection. Thus, the maxlen [see
netbuf in intro(3N)] field of each argument must be set before issuing
this function to indicate the maximum size of the buffer for each.
However, rcvcall may be NULL, in which case no information is given to
the user on return from tconnect.
By default, tconnect executes in synchronous mode, and will wait for the
destination user's response before returning control to the local user.
A successful return (that is, return value of zero) indicates that the
requested connection has been established. However, if ONDELAY or
ONONBLOCK is set (via topen or fcntl), tconnect executes in
asynchronous mode. In this case, the call will not wait for the remote
user's response, but will return control immediately to the local user
and return -1 with terrno set to TNODATA to indicate that the connection
has not yet been established. In this way, the function simply initiates
the connection establishment procedure by sending a connect request to
the destination transport user.
On failure, terrno may be set to one of the following:
TBADF The specified file descriptor does not refer to a
transport endpoint.
TOUTSTATE The function was issued in the wrong sequence.
TNODATA ONDELAY or ONONBLOCK was set, so the function
successfully initiated the connection establishment
procedure, but did not wait for a response from the
remote user.
TBADADDR The specified protocol address was in an incorrect
format or contained invalid information.
TBADOPT The specified protocol options were in an incorrect
format or contained invalid information.
TBADDATA The amount of user data specified was not within the
bounds supported by the transport provider as returned
in the connect field of the info argument of topen or
tgetinfo.
TACCES The user does not have permission to use the specified
address or options.
TBUFOVFLW The number of bytes allocated for an incoming argument
is not sufficient to store the value of that argument.
If executed in synchronous mode, the provider's state,
as seen by the user, changes to TDATAXFER, and the
connect indication information to be returned in
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t_connect(3N) UNIX System V(Networking Support Utilities) t_connect(3N)
rcvcall is discarded.
TLOOK An asynchronous event has occurred on this transport
endpoint and requires immediate attention.
TNOTSUPPORT This function is not supported by the underlying
transport provider.
TSYSERR A system error has occurred during execution of this
function.
SEE ALSO
intro(3N), taccept(3N), tgetinfo(3N), tlisten(3N), topen(3N),
toptmgmt(3N), trcvconnect(3N)
Programmer's Guide: Networking Interfaces
DIAGNOSTICS
tconnect returns 0 on success and -1 on failure and terrno is set to
indicate the error.
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