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140 .IX Title "SSL_get_error 3"
141 .TH SSL_get_error 3 "0.9.6e" "2002-07-30" "OpenSSL"
144 SSL_get_error \- obtain result code for \s-1TLS/SSL\s0 I/O operation
146 .IX Header "SYNOPSIS"
148 \& #include <openssl/ssl.h>
151 \& int SSL_get_error(SSL *ssl, int ret);
154 .IX Header "DESCRIPTION"
155 \&\fISSL_get_error()\fR returns a result code (suitable for the C \*(L"switch\*(R"
156 statement) for a preceding call to \fISSL_connect()\fR, \fISSL_accept()\fR, \fISSL_do_handshake()\fR,
157 \&\fISSL_read()\fR, \fISSL_peek()\fR, or \fISSL_write()\fR on \fBssl\fR. The value returned by
158 that \s-1TLS/SSL\s0 I/O function must be passed to \fISSL_get_error()\fR in parameter
161 In addition to \fBssl\fR and \fBret\fR, \fISSL_get_error()\fR inspects the
162 current thread's OpenSSL error queue. Thus, \fISSL_get_error()\fR must be
163 used in the same thread that performed the \s-1TLS/SSL\s0 I/O operation, and no
164 other OpenSSL function calls should appear in between. The current
165 thread's error queue must be empty before the \s-1TLS/SSL\s0 I/O operation is
166 attempted, or \fISSL_get_error()\fR will not work reliably.
168 .IX Header "RETURN VALUES"
169 The following return values can currently occur:
170 .Ip "\s-1SSL_ERROR_NONE\s0" 4
171 .IX Item "SSL_ERROR_NONE"
172 The \s-1TLS/SSL\s0 I/O operation completed. This result code is returned
173 if and only if \fBret > 0\fR.
174 .Ip "\s-1SSL_ERROR_ZERO_RETURN\s0" 4
175 .IX Item "SSL_ERROR_ZERO_RETURN"
176 The \s-1TLS/SSL\s0 connection has been closed. If the protocol version is \s-1SSL\s0 3.0
177 or \s-1TLS\s0 1.0, this result code is returned only if a closure
178 alert has occurred in the protocol, i.e. if the connection has been
179 closed cleanly. Note that in this case \fB\s-1SSL_ERROR_ZERO_RETURN\s0\fR
180 does not necessarily indicate that the underlying transport
182 .Ip "\s-1SSL_ERROR_WANT_READ\s0, \s-1SSL_ERROR_WANT_WRITE\s0" 4
183 .IX Item "SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE"
184 The operation did not complete; the same \s-1TLS/SSL\s0 I/O function should be
185 called again later. If, by then, the underlying \fB\s-1BIO\s0\fR has data
186 available for reading (if the result code is \fB\s-1SSL_ERROR_WANT_READ\s0\fR)
187 or allows writing data (\fB\s-1SSL_ERROR_WANT_WRITE\s0\fR), then some \s-1TLS/SSL\s0
188 protocol progress will take place, i.e. at least part of an \s-1TLS/SSL\s0
189 record will be read or written. Note that the retry may again lead to
190 a \fB\s-1SSL_ERROR_WANT_READ\s0\fR or \fB\s-1SSL_ERROR_WANT_WRITE\s0\fR condition.
191 There is no fixed upper limit for the number of iterations that
192 may be necessary until progress becomes visible at application
195 For socket \fB\s-1BIO\s0\fRs (e.g. when \fISSL_set_fd()\fR was used), \fIselect()\fR or
196 \&\fIpoll()\fR on the underlying socket can be used to find out when the
197 \&\s-1TLS/SSL\s0 I/O function should be retried.
199 Caveat: Any \s-1TLS/SSL\s0 I/O function can lead to either of
200 \&\fB\s-1SSL_ERROR_WANT_READ\s0\fR and \fB\s-1SSL_ERROR_WANT_WRITE\s0\fR. In particular,
201 \&\fISSL_read()\fR or \fISSL_peek()\fR may want to write data and \fISSL_write()\fR may want
202 to read data. This is mainly because \s-1TLS/SSL\s0 handshakes may occur at any
203 time during the protocol (initiated by either the client or the server);
204 \&\fISSL_read()\fR, \fISSL_peek()\fR, and \fISSL_write()\fR will handle any pending handshakes.
205 .Ip "\s-1SSL_ERROR_WANT_CONNECT\s0, \s-1SSL_ERROR_WANT_ACCEPT\s0" 4
206 .IX Item "SSL_ERROR_WANT_CONNECT, SSL_ERROR_WANT_ACCEPT"
207 The operation did not complete; the same \s-1TLS/SSL\s0 I/O function should be
208 called again later. The underlying \s-1BIO\s0 was not connected yet to the peer
209 and the call would block in \fIconnect()\fR/\fIaccept()\fR. The \s-1SSL\s0 function should be
210 called again when the connection is established. These messages can only
211 appear with a \fIBIO_s_connect()\fR or \fIBIO_s_accept()\fR \s-1BIO\s0, respectively.
212 In order to find out, when the connection has been successfully established,
213 on many platforms \fIselect()\fR or \fIpoll()\fR for writing on the socket file descriptor
215 .Ip "\s-1SSL_ERROR_WANT_X509_LOOKUP\s0" 4
216 .IX Item "SSL_ERROR_WANT_X509_LOOKUP"
217 The operation did not complete because an application callback set by
218 \&\fISSL_CTX_set_client_cert_cb()\fR has asked to be called again.
219 The \s-1TLS/SSL\s0 I/O function should be called again later.
220 Details depend on the application.
221 .Ip "\s-1SSL_ERROR_SYSCALL\s0" 4
222 .IX Item "SSL_ERROR_SYSCALL"
223 Some I/O error occurred. The OpenSSL error queue may contain more
224 information on the error. If the error queue is empty
225 (i.e. \fIERR_get_error()\fR returns 0), \fBret\fR can be used to find out more
226 about the error: If \fBret == 0\fR, an \s-1EOF\s0 was observed that violates
227 the protocol. If \fBret == \-1\fR, the underlying \fB\s-1BIO\s0\fR reported an
228 I/O error (for socket I/O on Unix systems, consult \fBerrno\fR for details).
229 .Ip "\s-1SSL_ERROR_SSL\s0" 4
230 .IX Item "SSL_ERROR_SSL"
231 A failure in the \s-1SSL\s0 library occurred, usually a protocol error. The
232 OpenSSL error queue contains more information on the error.
234 .IX Header "SEE ALSO"
238 \&\fISSL_get_error()\fR was added in SSLeay 0.8.