=head1 NAME
-SSL_get_error - obtain result code for SSL I/O operation
+SSL_get_error - obtain result code for TLS/SSL I/O operation
=head1 SYNOPSIS
#include <openssl/ssl.h>
- int SSL_get_error(SSL *ssl, int ret);
+ 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_read(), or SSL_write() on B<ssl>. The value returned by that
-SSL I/O function must be passed to SSL_get_error() in parameter
+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 SSL I/O operation, and no
-other OpenSSL function calls should appear inbetween. The current
-thread's error queue must be empty before the SSL I/O operation is
+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
=item SSL_ERROR_NONE
-The SSL I/O operation completed. This result code is returned
-if and only if B<ret > 0>.
+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 SSL connection has been closed. If the protocol version is SSL 3.0
+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
-alerts has occured in the protocol, i.e. if the connection has been
-closed cleanly.
+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 SSL I/O function should be
-called again later. There will be protocol progress 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>).
-For socket B<BIO>s (e.g. when SSL_set_fd() was used) this means that
-select() or poll() on the underlying socket can be used to find out
-when the SSL I/O function should be retried.
-
-Caveat: Any SSL I/O function can lead to either of
-B<SSL_ERROR_WANT_READ> and B<SSL_ERROR_WANT_WRITE>, i.e. SSL_read()
-may want to write data and SSL_write() may want to read data.
+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 SSL I/O function should be called again later.
+The TLS/SSL I/O function should be called again later.
Details depend on the application.
=item SSL_ERROR_SYSCALL
=item SSL_ERROR_SSL
-A failure in the SSL library occured, usually a protocol error. The
+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
-ssl(3), err(3)
+L<ssl(3)|ssl(3)>, L<err(3)|err(3)>
=head1 HISTORY
projects / openssl.git / blobdiff