'\" te
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.TH SASL_CLIENT_START 3SASL "May 13, 2017"
.SH NAME
sasl_client_start \- perform a step in the authentication negotiation
.SH SYNOPSIS
.LP
.nf
\fBcc\fR [ \fIflag\fR ... ] \fIfile\fR ... \fB-lsasl\fR   [ \fIlibrary\fR ... ]
#include <sasl/sasl.h>

\fBint\fR \fBsasl_client_start\fR(\fBsasl_conn_t *\fR\fIconn\fR, \fBconst char *\fR\fImechlist\fR,
     \fBsasl_interact_t **\fR\fIprompt_need\fR, \fBconst char **\fR\fIclientout\fR,
     \fBunsigned *\fR\fIclientoutlen\fR, \fBconst char **\fR\fImech\fR);
.fi

.SH DESCRIPTION
.LP
Use the \fBsasl_client_start()\fR interface to select a mechanism for
authentication and start the authentication session. The \fImechlist\fR
parameter holds the list of mechanisms that the client might like to use. The
mechanisms in the list are not necessarily supported by the client, nor are the
mechanisms necessarily valid. SASL determines which of the mechanisms to use
based upon the security preferences specified earlier. The list of mechanisms
is typically a list of mechanisms that the server supports, acquired from a
capability request.
.sp
.LP
If \fBSASL_INTERACT\fR is returned, the library needs some values to be filled
in before it can proceed. The \fIprompt_need\fR structure is filled in with
requests. The application fullfills these requests and calls
\fBsasl_client_start()\fR again with identical parameters. The
\fIprompt_need\fR parameter is the same pointer as before, but it is filled in
by the application.
.SH PARAMETERS
.ne 2
.na
\fB\fIconn\fR\fR
.ad
.RS 16n
The SASL connection context.
.RE

.sp
.ne 2
.na
\fB\fImechlist\fR\fR
.ad
.RS 16n
A list of mechanism that the server has available. Punctuation is ignored.
.RE

.sp
.ne 2
.na
\fB\fIprompt_need\fR\fR
.ad
.RS 16n
A list of prompts that are needed to continue, if necessary.
.RE

.sp
.ne 2
.na
\fB\fIclientout\fR\fR
.ad
.br
.na
\fB\fIclientoutlen\fR\fR
.ad
.RS 16n
\fIclientout\fR and \fIclientoutlen\fR are created. They contain the initial
client response to send to the server. It is the job of the client to send them
over the network to the server. Any protocol specific encodingthat is
necessary, for example \fBbase64\fR encoding, must be done by the client.
.sp
If the protocol lacks client-send-first capability, then set \fIclientout\fR to
\fINULL\fR. If there is no initial client-send, then *\fIclientout\fR will be
set to \fINULL\fR on return.
.RE

.sp
.ne 2
.na
\fB\fImech\fR\fR
.ad
.RS 16n
Contains the name of the chosen SASL mechanism, upon success.
.RE

.SH RETURN VALUES
.LP
\fBsasl_client_start()\fR returns an integer that corresponds to a SASL error
code.
.SH ERRORS
.ne 2
.na
\fB\fBSASL_CONTINUE\fR\fR
.ad
.RS 17n
The call to \fBsasl_client_start()\fR was successful, and more steps are needed
in the authentication.
.RE

.sp
.LP
All other error codes indicate an error situation that must be handled, or the
authentication session should be quit. See \fBsasl_errors\fR(3SASL) for
information on SASL error codes.
.SH ATTRIBUTES
.LP
See \fBattributes\fR(5) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	Evolving
_
MT-Level	Safe
.TE

.SH SEE ALSO
.LP
\fBsasl_errors\fR(3SASL), \fBattributes\fR(5)