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Name

t_connect - establish a connection with another transport user

Synopsis

cc [ flag ... ] file ... -lnsl [ library ... ]

#include <tiuser.h>

int t_connect(int fildes, const struct t_call *sndcall, struct t_call *rcvcall);

MT-Level

MT-Safe

Description

This function enables a transport user to request a connection to the specified destination transport user. fildes identifies the local transport endpoint where communication will be established, while sndcall and rcvcall point to a t_call 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.

The address is specified in the netbuf structure which has the following format: 


struct netbuf {unsigned int maxlen;unsigned int len;char *buf;}

where maxlen specifies the maximum length of the buffer in bytes, len specifies the bytes of data in the buffer, and buf points to the buffer that contains the data.

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 t_open(3N) or t_getinfo(3N) . If the len (see netbuf in t_connect(3N) ) 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 t_connect(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 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, return value of zero) indicates that the requested connection has been established. However, if O_NDELAY or O_NONBLOCK is set (using t_open(3N) or fcntl(2) ), 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. On failure t_connect() returns -1, t_errno is set to indicate the error, and possibly errno is set.

Errors

On failure, t_errno will 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_NDELAY or 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, errno will be set to the specific error.

See Also

fcntl(2) , t_accept(3N) , t_getinfo(3N) , t_listen(3N) , t_open(3N) , t_optmgmt(3N) , t_rcvconnect(3N)

Notes

This interface is safe in multithreaded applications.

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