• NAME
• SYNOPSIS
• DESCRIPTION
• RETURN VALUES
• SEE ALSO
• HISTORY
• COPYRIGHT

NAME

SSL_get_error - obtain result code for TLS/SSL I/O operation

SYNOPSIS

 #include <openssl/ssl.h>
 
 int SSL_get_error(const SSL *ssl, int ret);

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_shutdown(), SSL_write_ex() or SSL_write() on ssl. The value returned by that TLS/SSL I/O function must be passed to SSL_get_error() in parameter ret.

In addition to ssl and 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.

RETURN VALUES

The following return values can currently occur:

SSL_ERROR_NONE

The TLS/SSL I/O operation completed. This result code is returned if and only if ret > 0.

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 SSL_ERROR_ZERO_RETURN does not necessarily indicate that the underlying transport has been closed.

SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE

The operation did not complete and can be retried later.

SSL_ERROR_WANT_READ is returned when the last operation was a read operation from a non-blocking BIO. It means that not enough data was available at this time to complete the operation. If at a later time the underlying BIO has data available for reading the same function can be called again.

SSL_read() and SSL_read_ex() can also set SSL_ERROR_WANT_READ when there is still unprocessed data available at either the SSL or the BIO layer, even for a blocking BIO. See 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.

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.

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 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 SSL_get_changed_async_fds(3). The TLS/SSL I/O function should be called again later. The function must be called from the same thread that the original call was made from.

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 SSL_set_mode(3) and a maximum limit has been set on the async job pool through a call to 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.

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 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.

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.

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.

Licensed under the Apache License 2.0 (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 https://www.openssl.org/source/license.html.