05a6347fec
Add some clarifications to the async documentation. Also changed ASYNC_pause_job() so that it returns success if you are not within the context of a job. This is so that engines can be used either asynchronously or synchronously and can treat an error from ASYNC_pause_job() as a real error. Reviewed-by: Rich Salz <rsalz@openssl.org>
126 lines
4.8 KiB
Text
126 lines
4.8 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(), SSL_peek(), 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 connection has been closed. If the protocol version is SSL 3.0
|
|
or TLS 1.0, 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<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; the same TLS/SSL I/O function should be
|
|
called again later. If, by then, the underlying B<BIO> has data
|
|
available for reading (if the result code is B<SSL_ERROR_WANT_READ>)
|
|
or allows writing data (B<SSL_ERROR_WANT_WRITE>), 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<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.
|
|
|
|
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() or SSL_peek() may want to write data and SSL_write() 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(), SSL_peek(), 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_async_wait_fd(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_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. ERR_get_error() returns 0), B<ret> can be used to find out more
|
|
about the error: If B<ret == 0>, an EOF was observed that violates
|
|
the protocol. If B<ret == -1>, the underlying B<BIO> reported an
|
|
I/O error (for socket I/O on Unix systems, consult B<errno> 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(3)>, L<err(3)>
|
|
|
|
=head1 HISTORY
|
|
|
|
SSL_ERROR_WANT_ASYNC was added in OpenSSL 1.1.0.
|
|
|
|
=cut
|