NAME [Toc] [Back]
t_connect() - establish a connection with another transport user
SYNOPSIS [Toc] [Back]
#include <xti.h> /* for X/OPEN Transport Interface - XTI */
/* or */
#include <tiuser.h> /* for Transport Layer Interface - TLI */
int t_connect (fd, sndcall, rcvcall);
struct t_call *sndcall;
struct t_call *rcvcall;
DESCRIPTION [Toc] [Back]
This function enables a transport user to request a connection to the
specified destination transport user. This function can only be
issued in the T_IDLE state. fd identifies the local transport endpoint
where communication will be established. sndcall and rcvcall point to
a t_call structure which contains the following members:
struct netbuf addr;
struct netbuf opt;
struct netbuf udata;
The type netbuf structure is defined in the <xti.h> or <tiuser.h>
header file. This structure, which is used to define buffer
parameters, has the following members:
unsigned int maxlen maximum byte length of the data buffer
unsigned int len actual byte length of data written to
char *buf points to buffer location
sndcall specifies information needed by the transport provider to
establish a connection. rcvcall specifies information that is
associated with the newly established connection.
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. 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 protocolspecific
information associated with the connection. udata points to
optional user data that may be returned by the destination transport
user during connection establishment. sequence has no meaning for this
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The opt argument permits users to define the options that may be
passed to the transport provider. These options are specific to the
underlying protocols of the transport provider and are described for
ISO and TCP protocols in Appendix A, "ISO Transport Protocol
Information," Appendix B, "Internet Protocol-specific Information,"
and Appendix F, "Headers and Definitions" of the CAE Specification
X/Open Transport Interface (XTI) manual. 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.
If the opt argument is used, the sndcall->opt.buf structure must point
to the corresponding options structures. For XTI over the OSI
transport provider, the options buffer should be a struct of type
isoco_options or tcp_options. For TLI, see the documentation for the
transport provider being used. The maxlen and buf fields of the
netbuf structure pointed by rcvcall->addr and rcvcall->opt must be set
before the call.
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 t_open() or
t_getinfo(). If the len 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
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 a null pointer, in which case no information is given to the
user on return from t_connect().
By default, t_connect() 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_NONBLOCK
is set (via t_open() or fcntl()), t_connect() 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. The t_rcvconnect()
function is used in conjunction with t_connect() to determine the
status of the requested connection.
When a synchronous t_connect() call is interrupted by the arrival of a
signal, the state of the corresponding transport endpoint is T_OUTCON,
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allowing a further call to either t_rcvconnect(), t_rcvdis(), or
Thread-Safeness [Toc] [Back]
The t_connect() function is safe to be called by multithreaded
applications, and it is thread-safe for both POSIX Threads and DCE
User Threads. It has a cancellation point. It is neither asynccancel
safe nor async-signal safe. Finally, it is not fork-safe.
Valid States [Toc] [Back]
RETURN VALUE [Toc] [Back]
Upon successful completion, a value of 0 is returned. Otherwise, a
value of -1 is returned and t_errno is set to indicate the error.
ERRORS [Toc] [Back]
[TBADF] The specified file descriptor does not refer to a
[TOUTSTATE] The function was issued in the wrong sequence.
[TNODATA] O_NONBLOCK was set, so the function successfully
initiated the connection establishment procedure,
but did not wait for a response from the remote
[TBADADDR] The specified protocol address was in an incorrect
format or contained illegal information.
[TBADOPT] The specified protocol options were in incorrect
format or contained illegal 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 (maxlen) is greater than zero but 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
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[TNOTSUPPORT] This function is not supported by the underlying
[TSYSERR] A system error has occurred during execution of
[TADDRBUSY] This transport provider does not support multiple
connections with the same local and remote
addresses. This error indicates that a connection
[TPROTO] (XTI only) This error indicates that a
communication problem has been detected between
XTI and the transport provider for which there is
no suitable XTI (t_errno).
FILES [Toc] [Back]
/usr/include/xti.h XTI data structures
/usr/include/tiuser.h TLI data structures
SEE ALSO [Toc] [Back]
fcntl(2), t_accept(3), t_alloc(3), t_getinfo(3), t_listen(3),
STANDARDS CONFORMANCE [Toc] [Back]
t_connect(): SVID2, XPG3, XPG4
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