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Editing: SSL_get_error.3
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Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .nh .SH "NAME" SSL_get_error \- obtain result code for TLS/SSL I/O operation .SH "SYNOPSIS" .IX Header "SYNOPSIS" .Vb 1 \& #include <openssl/ssl.h> \& \& int SSL_get_error(const SSL *ssl, int ret); .Ve .SH "DESCRIPTION" .IX Header "DESCRIPTION" \&\fBSSL_get_error()\fR returns a result code (suitable for the C \*(L"switch\*(R" statement) for a preceding call to \fBSSL_connect()\fR, \fBSSL_accept()\fR, \fBSSL_do_handshake()\fR, \&\fBSSL_read()\fR, \fBSSL_peek()\fR, or \fBSSL_write()\fR on \fBssl\fR. The value returned by that \s-1TLS/SSL I/O\s0 function must be passed to \fBSSL_get_error()\fR in parameter \&\fBret\fR. .PP In addition to \fBssl\fR and \fBret\fR, \fBSSL_get_error()\fR inspects the current thread's OpenSSL error queue. Thus, \fBSSL_get_error()\fR must be used in the same thread that performed the \s-1TLS/SSL I/O\s0 operation, and no other OpenSSL function calls should appear in between. The current thread's error queue must be empty before the \s-1TLS/SSL I/O\s0 operation is attempted, or \fBSSL_get_error()\fR will not work reliably. .SH "RETURN VALUES" .IX Header "RETURN VALUES" The following return values can currently occur: .IP "\s-1SSL_ERROR_NONE\s0" 4 .IX Item "SSL_ERROR_NONE" The \s-1TLS/SSL I/O\s0 operation completed. This result code is returned if and only if \fBret > 0\fR. .IP "\s-1SSL_ERROR_ZERO_RETURN\s0" 4 .IX Item "SSL_ERROR_ZERO_RETURN" The \s-1TLS/SSL\s0 connection has been closed. If the protocol version is \s-1SSL 3.0\s0 or higher, this result code is returned only if a closure alert has occurred in the protocol, i.e. if the connection has been closed cleanly. Note that in this case \fB\s-1SSL_ERROR_ZERO_RETURN\s0\fR does not necessarily indicate that the underlying transport has been closed. .IP "\s-1SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE\s0" 4 .IX Item "SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE" The operation did not complete; the same \s-1TLS/SSL I/O\s0 function should be called again later. If, by then, the underlying \fB\s-1BIO\s0\fR has data available for reading (if the result code is \fB\s-1SSL_ERROR_WANT_READ\s0\fR) or allows writing data (\fB\s-1SSL_ERROR_WANT_WRITE\s0\fR), then some \s-1TLS/SSL\s0 protocol progress will take place, i.e. at least part of an \s-1TLS/SSL\s0 record will be read or written. Note that the retry may again lead to a \fB\s-1SSL_ERROR_WANT_READ\s0\fR or \fB\s-1SSL_ERROR_WANT_WRITE\s0\fR condition. There is no fixed upper limit for the number of iterations that may be necessary until progress becomes visible at application protocol level. .Sp For socket \fB\s-1BIO\s0\fRs (e.g. when \fBSSL_set_fd()\fR was used), \fBselect()\fR or \&\fBpoll()\fR on the underlying socket can be used to find out when the \&\s-1TLS/SSL I/O\s0 function should be retried. .Sp Caveat: Any \s-1TLS/SSL I/O\s0 function can lead to either of \&\fB\s-1SSL_ERROR_WANT_READ\s0\fR and \fB\s-1SSL_ERROR_WANT_WRITE\s0\fR. In particular, \&\fBSSL_read()\fR or \fBSSL_peek()\fR may want to write data and \fBSSL_write()\fR may want to read data. This is mainly because \s-1TLS/SSL\s0 handshakes may occur at any time during the protocol (initiated by either the client or the server); \&\fBSSL_read()\fR, \fBSSL_peek()\fR, and \fBSSL_write()\fR will handle any pending handshakes. .IP "\s-1SSL_ERROR_WANT_CONNECT, SSL_ERROR_WANT_ACCEPT\s0" 4 .IX Item "SSL_ERROR_WANT_CONNECT, SSL_ERROR_WANT_ACCEPT" The operation did not complete; the same \s-1TLS/SSL I/O\s0 function should be called again later. The underlying \s-1BIO\s0 was not connected yet to the peer and the call would block in \fBconnect()\fR/\fBaccept()\fR. The \s-1SSL\s0 function should be called again when the connection is established. These messages can only appear with a \fBBIO_s_connect()\fR or \fBBIO_s_accept()\fR \s-1BIO,\s0 respectively. In order to find out, when the connection has been successfully established, on many platforms \fBselect()\fR or \fBpoll()\fR for writing on the socket file descriptor can be used. .IP "\s-1SSL_ERROR_WANT_X509_LOOKUP\s0" 4 .IX Item "SSL_ERROR_WANT_X509_LOOKUP" The operation did not complete because an application callback set by \&\fBSSL_CTX_set_client_cert_cb()\fR has asked to be called again. The \s-1TLS/SSL I/O\s0 function should be called again later. Details depend on the application. .IP "\s-1SSL_ERROR_SYSCALL\s0" 4 .IX Item "SSL_ERROR_SYSCALL" Some non-recoverable, fatal I/O error occurred. The OpenSSL error queue may contain more information on the error. For socket I/O on Unix systems, consult \&\fBerrno\fR for details. If this error occurs then no further I/O operations should be performed on the connection and \fBSSL_shutdown()\fR must not be called. .IP "\s-1SSL_ERROR_SSL\s0" 4 .IX Item "SSL_ERROR_SSL" A non-recoverable, fatal error in the \s-1SSL\s0 library occurred, usually a protocol error. The OpenSSL error queue contains more information on the error. If this error occurs then no further I/O operations should be performed on the connection and \fBSSL_shutdown()\fR must not be called. .SH "SEE ALSO" .IX Header "SEE ALSO" \&\fBssl\fR\|(3), \fBerr\fR\|(3) .SH "HISTORY" .IX Header "HISTORY" \&\fBSSL_get_error()\fR was added in SSLeay 0.8.
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