1 .\" $NetBSD: SSL_connect.3,v 1.14 2015/06/12 17:01:14 christos Exp $
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135 .\" ========================================================================
137 .IX Title "SSL_connect 3"
138 .TH SSL_connect 3 "2014-06-05" "1.0.1n" "OpenSSL"
139 .\" For nroff, turn off justification. Always turn off hyphenation; it makes
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144 SSL_connect \- initiate the TLS/SSL handshake with an TLS/SSL server
148 .IX Header "SYNOPSIS"
150 \& #include <openssl/ssl.h>
152 \& int SSL_connect(SSL *ssl);
155 .IX Header "DESCRIPTION"
156 \&\fISSL_connect()\fR initiates the \s-1TLS/SSL\s0 handshake with a server. The communication
157 channel must already have been set and assigned to the \fBssl\fR by setting an
158 underlying \fB\s-1BIO\s0\fR.
161 The behaviour of \fISSL_connect()\fR depends on the underlying \s-1BIO. \s0
163 If the underlying \s-1BIO\s0 is \fBblocking\fR, \fISSL_connect()\fR will only return once the
164 handshake has been finished or an error occurred.
166 If the underlying \s-1BIO\s0 is \fBnon-blocking\fR, \fISSL_connect()\fR will also return
167 when the underlying \s-1BIO\s0 could not satisfy the needs of \fISSL_connect()\fR
168 to continue the handshake, indicating the problem by the return value \-1.
169 In this case a call to \fISSL_get_error()\fR with the
170 return value of \fISSL_connect()\fR will yield \fB\s-1SSL_ERROR_WANT_READ\s0\fR or
171 \&\fB\s-1SSL_ERROR_WANT_WRITE\s0\fR. The calling process then must repeat the call after
172 taking appropriate action to satisfy the needs of \fISSL_connect()\fR.
173 The action depends on the underlying \s-1BIO.\s0 When using a non-blocking socket,
174 nothing is to be done, but \fIselect()\fR can be used to check for the required
175 condition. When using a buffering \s-1BIO,\s0 like a \s-1BIO\s0 pair, data must be written
176 into or retrieved out of the \s-1BIO\s0 before being able to continue.
178 .IX Header "RETURN VALUES"
179 The following return values can occur:
181 The \s-1TLS/SSL\s0 handshake was not successful but was shut down controlled and
182 by the specifications of the \s-1TLS/SSL\s0 protocol. Call \fISSL_get_error()\fR with the
183 return value \fBret\fR to find out the reason.
186 The \s-1TLS/SSL\s0 handshake was successfully completed, a \s-1TLS/SSL\s0 connection has been
190 The \s-1TLS/SSL\s0 handshake was not successful, because a fatal error occurred either
191 at the protocol level or a connection failure occurred. The shutdown was
192 not clean. It can also occur of action is need to continue the operation
193 for non-blocking BIOs. Call \fISSL_get_error()\fR with the return value \fBret\fR
194 to find out the reason.
196 .IX Header "SEE ALSO"
197 \&\fISSL_get_error\fR\|(3), \fISSL_accept\fR\|(3),
198 \&\fISSL_shutdown\fR\|(3), \fIssl\fR\|(3), \fIopenssl_bio\fR\|(3),
199 \&\fISSL_set_connect_state\fR\|(3),
200 \&\fISSL_do_handshake\fR\|(3),
201 \&\fISSL_CTX_new\fR\|(3)