(TLI/XTI)

t_connect(NET)

t_connect -- establish a connection with another transport user

Syntax

TLI syntax

cc . . . -lnsl

#include <sys/tiuser.h>

int t_connect (fd, sndcall, rcvcall)
int fd;
struct t_call *sndcall;
struct t_call *rcvcall;

XTI syntax

cc . . . -lxti

#include <xti.h>

int t_connect (fd, sndcall, rcvcall)
int fd;
struct t_call *sndcall;
struct t_call *rcvcall;

Description

The t_connect 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 netbuf(FP). 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 by t_open(NET) or t_getinfo(NET) If the len (see netbuf in netbuf(FP)) 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 netbuf(FP)) 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 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 (that is, a 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.

Return values

t_connect returns 0 on success and -1 on failure, and t_errno is set to indicate the error.

Diagnostics

On failure, t_errno may be set to one of the following:

[TACCES]: The user does not have permission to use the specified address or 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 specified file descriptor does not refer to a transport endpoint.
[TBADOPT]: The specified protocol options were in an incorrect format or contained illegal information.
[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.
[TNODATA]: O_NONBLOCK was set, so the function successfully initiated the connection establishment procedure, but did not wait for a response from the remote user.
[TNOTSUPPORT]: This function is not supported by the underlying transport provider.
[TOUTSTATE]: The function was issued in the wrong sequence.
[TSYSERR]: A system error has occurred during execution of this function.

Standards conformance

t_connect is conformant with:

AT&T SVID Issue 3 ;
X/Open CAE Specification, Networking Services, Issue 4, 1994. ;
and Intel386 Binary Compatibility Specification, Edition 2 (iBCSe2) .