=pod =head1 NAME SSL_get_error - obtain result code for TLS/SSL I/O operation =head1 SYNOPSIS #include int SSL_get_error(const SSL *ssl, int ret); =head1 DESCRIPTION SSL_get_error() returns a result code (suitable for the C "switch" statement) for a preceding call to SSL_connect(), SSL_accept(), SSL_do_handshake(), SSL_read_ex(), SSL_read(), SSL_peek_ex(), SSL_peek(), SSL_write_ex() or SSL_write() on B. The value returned by that TLS/SSL I/O function must be passed to SSL_get_error() in parameter B. In addition to B and B, SSL_get_error() inspects the current thread's OpenSSL error queue. Thus, SSL_get_error() must be used in the same thread that performed the TLS/SSL I/O operation, and no other OpenSSL function calls should appear in between. The current thread's error queue must be empty before the TLS/SSL I/O operation is attempted, or SSL_get_error() will not work reliably. =head1 RETURN VALUES The following return values can currently occur: =over 4 =item SSL_ERROR_NONE The TLS/SSL I/O operation completed. This result code is returned if and only if B 0>. =item SSL_ERROR_ZERO_RETURN The TLS/SSL connection has been closed. If the protocol version is SSL 3.0 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 B does not necessarily indicate that the underlying transport has been closed. =item SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE The operation did not complete; the same TLS/SSL I/O function should be called again later. If, by then, the underlying B has data available for reading (if the result code is B) or allows writing data (B), then some TLS/SSL protocol progress will take place, i.e. at least part of an TLS/SSL record will be read or written. Note that the retry may again lead to a B or B condition. There is no fixed upper limit for the number of iterations that may be necessary until progress becomes visible at application protocol level. For socket Bs (e.g. when SSL_set_fd() was used), select() or poll() on the underlying socket can be used to find out when the TLS/SSL I/O function should be retried. Caveat: Any TLS/SSL I/O function can lead to either of B and B. In particular, SSL_read_ex(), SSL_read(), SSL_peek_ex(), or SSL_peek() may want to write data and SSL_write() or SSL_write_ex() may want to read data. This is mainly because TLS/SSL handshakes may occur at any time during the protocol (initiated by either the client or the server); SSL_read_ex(), SSL_read(), SSL_peek_ex(), SSL_peek(), SSL_write_ex(), and SSL_write() will handle any pending handshakes. =item SSL_ERROR_WANT_CONNECT, SSL_ERROR_WANT_ACCEPT The operation did not complete; the same TLS/SSL I/O function should be called again later. The underlying BIO was not connected yet to the peer and the call would block in connect()/accept(). The SSL function should be called again when the connection is established. These messages can only appear with a BIO_s_connect() or BIO_s_accept() BIO, respectively. In order to find out, when the connection has been successfully established, on many platforms select() or poll() for writing on the socket file descriptor can be used. =item SSL_ERROR_WANT_X509_LOOKUP The operation did not complete because an application callback set by SSL_CTX_set_client_cert_cb() has asked to be called again. The TLS/SSL I/O function should be called again later. Details depend on the application. =item SSL_ERROR_WANT_ASYNC The operation did not complete because an asynchronous engine is still processing data. This will only occur if the mode has been set to SSL_MODE_ASYNC using L or L and an asynchronous capable engine is being used. An application can determine whether the engine has completed its processing using select() or poll() on the asynchronous wait file descriptor. This file descriptor is available by calling L or L. The TLS/SSL I/O function should be called again later. The function B be called from the same thread that the original call was made from. =item SSL_ERROR_WANT_ASYNC_JOB The asynchronous job could not be started because there were no async jobs available in the pool (see ASYNC_init_thread(3)). This will only occur if the mode has been set to SSL_MODE_ASYNC using L or L and a maximum limit has been set on the async job pool through a call to L. The application should retry the operation after a currently executing asynchronous operation for the current thread has completed. =item SSL_ERROR_WANT_EARLY The operation did not complete because an application callback set by SSL_CTX_set_early_cb() has asked to be called again. The TLS/SSL I/O function should be called again later. Details depend on the application. =item SSL_ERROR_SYSCALL Some non-recoverable I/O error occurred. The OpenSSL error queue may contain more information on the error. For socket I/O on Unix systems, consult B for details. =item SSL_ERROR_SSL A failure in the SSL library occurred, usually a protocol error. The OpenSSL error queue contains more information on the error. =back =head1 SEE ALSO L =head1 HISTORY SSL_ERROR_WANT_ASYNC was added in OpenSSL 1.1.0. SSL_ERROR_WANT_EARLY was added in OpenSSL 1.1.1. =head1 COPYRIGHT Copyright 2000-2017 The OpenSSL Project Authors. All Rights Reserved. Licensed under the OpenSSL license (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at L. =cut