173 lines
6.5 KiB
Text
173 lines
6.5 KiB
Text
=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 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.
|
|
|
|
This value can also be returned for other errors, check the error queue 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<ssl(7)>
|
|
|
|
=head1 HISTORY
|
|
|
|
SSL_ERROR_WANT_ASYNC was added in OpenSSL 1.1.0.
|
|
SSL_ERROR_WANT_CLIENT_HELLO_CB 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
|