T_CONNECT(3N)

NAME
t_connect - establish a connection with another transport user

SYNOPSIS

#include <tiuser.h>

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

DESCRIPTION

t_connect() 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.

The maxlen, len, and buf members of the netbuf structure are described in t_accept(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.

opt 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 0. In this case, the transport provider may use default options.

udata 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(3N) or t_getinfo(3N). If the len field of udata is 0 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 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 (a return value of 0) indicates that the requested connection has been established. However, if T_NDELAY is set (using 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.

-1  on failure and sets t_errno to indicate the error.

ERRORS

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 transport 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
    T_NDELAY 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
    The function failed due to a system error and set errno to indicate the error.

SEE ALSO
intro(3), t_accept(3N), t_getinfo(3N), t_listen(3N), t_open(3N), t_optmgmt(3N), t_rcvconnect(3N)