Merge branch 'vendor/OPENSSL'
[dragonfly.git] / secure / lib / libssl / man / SSL_get_error.3
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129.\" ========================================================================
130.\"
131.IX Title "SSL_get_error 3"
18ed9402 132.TH SSL_get_error 3 "2008-09-27" "0.9.8i" "OpenSSL"
984263bc 133.SH "NAME"
a7d27d5a 134SSL_get_error \- obtain result code for TLS/SSL I/O operation
984263bc 135.SH "SYNOPSIS"
e056f0e0 136.IX Header "SYNOPSIS"
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137.Vb 1
138\& #include <openssl/ssl.h>
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139.Ve
140.PP
141.Vb 1
a561f9ff 142\& int SSL_get_error(const SSL *ssl, int ret);
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143.Ve
144.SH "DESCRIPTION"
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145.IX Header "DESCRIPTION"
146\&\fISSL_get_error()\fR returns a result code (suitable for the C \*(L"switch\*(R"
984263bc 147statement) for a preceding call to \fISSL_connect()\fR, \fISSL_accept()\fR, \fISSL_do_handshake()\fR,
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148\&\fISSL_read()\fR, \fISSL_peek()\fR, or \fISSL_write()\fR on \fBssl\fR. The value returned by
149that \s-1TLS/SSL\s0 I/O function must be passed to \fISSL_get_error()\fR in parameter
150\&\fBret\fR.
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151.PP
152In addition to \fBssl\fR and \fBret\fR, \fISSL_get_error()\fR inspects the
153current thread's OpenSSL error queue. Thus, \fISSL_get_error()\fR must be
e056f0e0 154used in the same thread that performed the \s-1TLS/SSL\s0 I/O operation, and no
984263bc 155other OpenSSL function calls should appear in between. The current
e056f0e0 156thread's error queue must be empty before the \s-1TLS/SSL\s0 I/O operation is
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157attempted, or \fISSL_get_error()\fR will not work reliably.
158.SH "RETURN VALUES"
e056f0e0 159.IX Header "RETURN VALUES"
984263bc 160The following return values can currently occur:
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161.IP "\s-1SSL_ERROR_NONE\s0" 4
162.IX Item "SSL_ERROR_NONE"
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163The \s-1TLS/SSL\s0 I/O operation completed. This result code is returned
164if and only if \fBret > 0\fR.
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165.IP "\s-1SSL_ERROR_ZERO_RETURN\s0" 4
166.IX Item "SSL_ERROR_ZERO_RETURN"
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167The \s-1TLS/SSL\s0 connection has been closed. If the protocol version is \s-1SSL\s0 3.0
168or \s-1TLS\s0 1.0, this result code is returned only if a closure
169alert has occurred in the protocol, i.e. if the connection has been
170closed cleanly. Note that in this case \fB\s-1SSL_ERROR_ZERO_RETURN\s0\fR
171does not necessarily indicate that the underlying transport
172has been closed.
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173.IP "\s-1SSL_ERROR_WANT_READ\s0, \s-1SSL_ERROR_WANT_WRITE\s0" 4
174.IX Item "SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE"
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175The operation did not complete; the same \s-1TLS/SSL\s0 I/O function should be
176called again later. If, by then, the underlying \fB\s-1BIO\s0\fR has data
177available for reading (if the result code is \fB\s-1SSL_ERROR_WANT_READ\s0\fR)
178or allows writing data (\fB\s-1SSL_ERROR_WANT_WRITE\s0\fR), then some \s-1TLS/SSL\s0
179protocol progress will take place, i.e. at least part of an \s-1TLS/SSL\s0
180record will be read or written. Note that the retry may again lead to
181a \fB\s-1SSL_ERROR_WANT_READ\s0\fR or \fB\s-1SSL_ERROR_WANT_WRITE\s0\fR condition.
182There is no fixed upper limit for the number of iterations that
183may be necessary until progress becomes visible at application
184protocol level.
185.Sp
186For socket \fB\s-1BIO\s0\fRs (e.g. when \fISSL_set_fd()\fR was used), \fIselect()\fR or
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187\&\fIpoll()\fR on the underlying socket can be used to find out when the
188\&\s-1TLS/SSL\s0 I/O function should be retried.
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189.Sp
190Caveat: Any \s-1TLS/SSL\s0 I/O function can lead to either of
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191\&\fB\s-1SSL_ERROR_WANT_READ\s0\fR and \fB\s-1SSL_ERROR_WANT_WRITE\s0\fR. In particular,
192\&\fISSL_read()\fR or \fISSL_peek()\fR may want to write data and \fISSL_write()\fR may want
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193to read data. This is mainly because \s-1TLS/SSL\s0 handshakes may occur at any
194time during the protocol (initiated by either the client or the server);
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195\&\fISSL_read()\fR, \fISSL_peek()\fR, and \fISSL_write()\fR will handle any pending handshakes.
196.IP "\s-1SSL_ERROR_WANT_CONNECT\s0, \s-1SSL_ERROR_WANT_ACCEPT\s0" 4
197.IX Item "SSL_ERROR_WANT_CONNECT, SSL_ERROR_WANT_ACCEPT"
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198The operation did not complete; the same \s-1TLS/SSL\s0 I/O function should be
199called again later. The underlying \s-1BIO\s0 was not connected yet to the peer
200and the call would block in \fIconnect()\fR/\fIaccept()\fR. The \s-1SSL\s0 function should be
201called again when the connection is established. These messages can only
202appear with a \fIBIO_s_connect()\fR or \fIBIO_s_accept()\fR \s-1BIO\s0, respectively.
203In order to find out, when the connection has been successfully established,
204on many platforms \fIselect()\fR or \fIpoll()\fR for writing on the socket file descriptor
205can be used.
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206.IP "\s-1SSL_ERROR_WANT_X509_LOOKUP\s0" 4
207.IX Item "SSL_ERROR_WANT_X509_LOOKUP"
984263bc 208The operation did not complete because an application callback set by
e056f0e0 209\&\fISSL_CTX_set_client_cert_cb()\fR has asked to be called again.
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210The \s-1TLS/SSL\s0 I/O function should be called again later.
211Details depend on the application.
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212.IP "\s-1SSL_ERROR_SYSCALL\s0" 4
213.IX Item "SSL_ERROR_SYSCALL"
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214Some I/O error occurred. The OpenSSL error queue may contain more
215information on the error. If the error queue is empty
216(i.e. \fIERR_get_error()\fR returns 0), \fBret\fR can be used to find out more
217about the error: If \fBret == 0\fR, an \s-1EOF\s0 was observed that violates
218the protocol. If \fBret == \-1\fR, the underlying \fB\s-1BIO\s0\fR reported an
219I/O error (for socket I/O on Unix systems, consult \fBerrno\fR for details).
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220.IP "\s-1SSL_ERROR_SSL\s0" 4
221.IX Item "SSL_ERROR_SSL"
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222A failure in the \s-1SSL\s0 library occurred, usually a protocol error. The
223OpenSSL error queue contains more information on the error.
224.SH "SEE ALSO"
a7d27d5a 225.IX Header "SEE ALSO"
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226\&\fIssl\fR\|(3), \fIerr\fR\|(3)
227.SH "HISTORY"
984263bc 228.IX Header "HISTORY"
e056f0e0 229\&\fISSL_get_error()\fR was added in SSLeay 0.8.