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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 \& \& int SSL_get_error(const SSL *ssl, int ret); .Ve .SH "DESCRIPTION" .IX Header "DESCRIPTION" \&\fISSL_get_error()\fR returns a result code (suitable for the C \*(L"switch\*(R" statement) for a preceding call to \fISSL_connect()\fR, \fISSL_accept()\fR, \fISSL_do_handshake()\fR, \&\fISSL_read()\fR, \fISSL_peek()\fR, or \fISSL_write()\fR on \fBssl\fR. The value returned by that \&\s-1TLS/SSL I/O\s0 function must be passed to \fISSL_get_error()\fR in parameter \fBret\fR. .PP In addition to \fBssl\fR and \fBret\fR, \fISSL_get_error()\fR inspects the current thread's OpenSSL error queue. Thus, \fISSL_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 \fISSL_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 \s-1TLS 1.0,\s0 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 \fISSL_set_fd()\fR was used), \fIselect()\fR or \&\fIpoll()\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, \&\fISSL_read()\fR or \fISSL_peek()\fR may want to write data and \fISSL_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); \&\fISSL_read()\fR, \fISSL_peek()\fR, and \fISSL_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 \fIconnect()\fR/\fIaccept()\fR. The \s-1SSL\s0 function should be called again when the connection is established. These messages can only appear with a \fIBIO_s_connect()\fR or \fIBIO_s_accept()\fR \s-1BIO,\s0 respectively. In order to find out, when the connection has been successfully established, on many platforms \fIselect()\fR or \fIpoll()\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 \&\fISSL_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 I/O error occurred. The OpenSSL error queue may contain more information on the error. If the error queue is empty (i.e. \fIERR_get_error()\fR returns 0), \fBret\fR can be used to find out more about the error: If \fBret == 0\fR, an \s-1EOF\s0 was observed that violates the protocol. If \fBret == \-1\fR, the underlying \fB\s-1BIO\s0\fR reported an I/O error (for socket I/O on Unix systems, consult \fBerrno\fR for details). .IP "\s-1SSL_ERROR_SSL\s0" 4 .IX Item "SSL_ERROR_SSL" A failure in the \s-1SSL\s0 library occurred, usually a protocol error. The OpenSSL error queue contains more information on the error. .SH "SEE ALSO" .IX Header "SEE ALSO" \&\fIssl\fR\|(3), \fIerr\fR\|(3) .SH "HISTORY" .IX Header "HISTORY" \&\fISSL_get_error()\fR was added in SSLeay 0.8.