TCONNECT(3N) DG/UX 4.30 TCONNECT(3N)
NAME
t_connect - 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
t_call structure which 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(3). 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
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TCONNECT(3N) DG/UX 4.30 TCONNECT(3N)
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 by topen
(3N) or tgetinfo (3N). If the len [see netbuf in intro(3)]
field of udata is zero 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(3)] 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 (i.e. return
value of zero) indicates that the requested connection has
been established. However, if O_NDELAY 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 t_errno 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, t_errno 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] O_NDELAY 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 illegal
information.
[TBADOPT] The specified protocol options were in an
incorrect format or contained illegal
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TCONNECT(3N) DG/UX 4.30 TCONNECT(3N)
information.
[TBADDATA] The amount of user data specified was not
within the bounds allowed by the
transport provider.
[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 T_DATAXFER, and the connect
indication information to be returned in
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(3), t_accept(3N), t_getinfo(3N), t_listen(3N),
t_open(3N), t_optmgmt(3N), t_rcvconnect(3N).
DIAGNOSTICS
tconnect returns 0 on success and -1 on failure and t_errno
is set to indicate the error.
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