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Diffstat (limited to 'crypto/openssl/doc/man3/SSL_get_error.pod')
-rw-r--r-- | crypto/openssl/doc/man3/SSL_get_error.pod | 176 |
1 files changed, 176 insertions, 0 deletions
diff --git a/crypto/openssl/doc/man3/SSL_get_error.pod b/crypto/openssl/doc/man3/SSL_get_error.pod new file mode 100644 index 000000000000..5a7a4b7058ef --- /dev/null +++ b/crypto/openssl/doc/man3/SSL_get_error.pod @@ -0,0 +1,176 @@ +=pod + +=head1 NAME + +SSL_get_error - obtain result code for TLS/SSL I/O operation + +=head1 SYNOPSIS + + #include <openssl/ssl.h> + + 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<ssl>. The value returned by that TLS/SSL I/O function must be +passed to SSL_get_error() in parameter B<ret>. + +In addition to B<ssl> and B<ret>, 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<ret E<gt> 0>. + +=item SSL_ERROR_ZERO_RETURN + +The TLS/SSL peer has closed the connection for writing by sending the +close_notify alert. +No more data can be read. +Note that B<SSL_ERROR_ZERO_RETURN> 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 and can be retried later. + +B<SSL_ERROR_WANT_READ> is returned when the last operation was a read +operation from a non-blocking B<BIO>. +It means that not enough data was available at this time to complete the +operation. +If at a later time the underlying B<BIO> has data available for reading the same +function can be called again. + +SSL_read() and SSL_read_ex() can also set B<SSL_ERROR_WANT_READ> when there is +still unprocessed data available at either the B<SSL> or the B<BIO> layer, even +for a blocking B<BIO>. +See L<SSL_read(3)> for more information. + +B<SSL_ERROR_WANT_WRITE> is returned when the last operation was a write +to a non-blocking B<BIO> and it was unable to sent all data to the B<BIO>. +When the B<BIO> is writeable again, the same function can be called again. + +Note that the retry may again lead to an B<SSL_ERROR_WANT_READ> or +B<SSL_ERROR_WANT_WRITE> condition. +There is no fixed upper limit for the number of iterations that +may be necessary until progress becomes visible at application +protocol level. + +It is safe to call SSL_read() or SSL_read_ex() when more data is available +even when the call that set this error was an SSL_write() or SSL_write_ex(). +However if the call was an SSL_write() or SSL_write_ex(), it should be called +again to continue sending the application data. + +For socket B<BIO>s (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<SSL_ERROR_WANT_READ> and B<SSL_ERROR_WANT_WRITE>. +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<SSL_CTX_set_mode(3)> or L<SSL_set_mode(3)> 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<SSL_get_all_async_fds(3)> or L<SSL_get_changed_async_fds(3)>. The TLS/SSL I/O +function should be called again later. The function B<must> 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<SSL_CTX_set_mode(3)> or +L<SSL_set_mode(3)> and a maximum limit has been set on the async job pool +through a call to L<ASYNC_init_thread(3)>. The application should retry the +operation after a currently executing asynchronous operation for the current +thread has completed. + +=item SSL_ERROR_WANT_CLIENT_HELLO_CB + +The operation did not complete because an application callback set by +SSL_CTX_set_client_hello_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, fatal I/O error occurred. The OpenSSL error queue may +contain more information on the error. For socket I/O on Unix systems, consult +B<errno> for details. If this error occurs then no further I/O operations should +be performed on the connection and SSL_shutdown() must not be called. + +This value can also be returned for other errors, check the error queue for +details. + +=item SSL_ERROR_SSL + +A non-recoverable, fatal error in the SSL 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 SSL_shutdown() must not be called. + +=back + +=head1 SEE ALSO + +L<ssl(7)> + +=head1 HISTORY + +The SSL_ERROR_WANT_ASYNC error code was added in OpenSSL 1.1.0. +The SSL_ERROR_WANT_CLIENT_HELLO_CB error code was added in OpenSSL 1.1.1. + +=head1 COPYRIGHT + +Copyright 2000-2018 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<https://www.openssl.org/source/license.html>. + +=cut |