.rn '' }`
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..
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.TH SSL_do_handshake 3 "0.9.7d" "2/Sep/2004" "OpenSSL"
.UC
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.rm #[ #] #H #V #F C
.SH "NAME"
SSL_do_handshake \- perform a TLS/SSL handshake
.SH "SYNOPSIS"
.PP
.Vb 1
\& #include <openssl/ssl.h>
.Ve
.Vb 1
\& int SSL_do_handshake(SSL *ssl);
.Ve
.SH "DESCRIPTION"
\fISSL_do_handshake()\fR will wait for a SSL/TLS handshake to take place. If the
connection is in client mode, the handshake will be started. The handshake
routines may have to be explicitly set in advance using either
SSL_set_connect_state(3) or
SSL_set_accept_state(3).
.SH "NOTES"
The behaviour of \fISSL_do_handshake()\fR depends on the underlying BIO.
.PP
If the underlying BIO is \fBblocking\fR, \fISSL_do_handshake()\fR will only return
once the handshake has been finished or an error occurred, except for SGC
(Server Gated Cryptography). For SGC, \fISSL_do_handshake()\fR may return with \-1,
but \fISSL_get_error()\fR will yield \fBSSL_ERROR_WANT_READ/WRITE\fR and
\fISSL_do_handshake()\fR should be called again.
.PP
If the underlying BIO is \fBnon-blocking\fR, \fISSL_do_handshake()\fR will also return
when the underlying BIO could not satisfy the needs of \fISSL_do_handshake()\fR
to continue the handshake. In this case a call to \fISSL_get_error()\fR with the
return value of \fISSL_do_handshake()\fR will yield \fBSSL_ERROR_WANT_READ\fR or
\fBSSL_ERROR_WANT_WRITE\fR. The calling process then must repeat the call after
taking appropriate action to satisfy the needs of \fISSL_do_handshake()\fR.
The action depends on the underlying BIO. When using a non-blocking socket,
nothing is to be done, but \fIselect()\fR can be used to check for the required
condition. When using a buffering BIO, like a BIO pair, data must be written
into or retrieved out of the BIO before being able to continue.
.SH "RETURN VALUES"
The following return values can occur:
.Ip "1" 4
The \s-1TLS/SSL\s0 handshake was successfully completed, a \s-1TLS/SSL\s0 connection has been
established.
.Ip "0" 4
The \s-1TLS/SSL\s0 handshake was not successful but was shut down controlled and
by the specifications of the \s-1TLS/SSL\s0 protocol. Call \fISSL_get_error()\fR with the
return value \fBret\fR to find out the reason.
.Ip "<0" 4
The \s-1TLS/SSL\s0 handshake was not successful because a fatal error occurred either
at the protocol level or a connection failure occurred. The shutdown was
not clean. It can also occur of action is need to continue the operation
for non-blocking BIOs. Call \fISSL_get_error()\fR with the return value \fBret\fR
to find out the reason.
.SH "SEE ALSO"
SSL_get_error(3), SSL_connect(3),
SSL_accept(3), ssl(3), bio(3),
SSL_set_connect_state(3)

.rn }` ''
.IX Title "SSL_do_handshake 3"
.IX Name "SSL_do_handshake - perform a TLS/SSL handshake"

.IX Header "NAME"

.IX Header "SYNOPSIS"

.IX Header "DESCRIPTION"

.IX Header "NOTES"

.IX Header "RETURN VALUES"

.IX Item "1"

.IX Item "0"

.IX Item "<0"

.IX Header "SEE ALSO"