SSL_get_error(3) OpenSSL SSL_get_error(3)NAMESSL_get_error - obtain result code for TLS/SSL I/O
operation
SYNOPSIS
#include <openssl/ssl.h>
int SSL_get_error(SSL *ssl, int ret);
DESCRIPTIONSSL_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 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 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
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; the same TLS/SSL I/O
function should be called again later. There will be
protocol progress if, by then, the underlying BIO has
data available for reading (if the result code is
SSL_ERROR_WANT_READ) or allows writing data
(SSL_ERROR_WANT_WRITE). For socket BIOs (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 TLS/SSL I/O function should be retried.
Caveat: Any TLS/SSL I/O function can lead to either of
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SSL_get_error(3) OpenSSL SSL_get_error(3)
SSL_ERROR_WANT_READ and SSL_ERROR_WANT_WRITE, i.e.
SSL_read() may want to write data and SSL_write() may
want to read data.
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_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), ret
can be used to find out more about the error: If ret
== 0, an EOF was observed that violates the protocol.
If ret == -1, the underlying BIO reported an I/O error
(for socket I/O on Unix systems, consult errno for
details).
SSL_ERROR_SSL
A failure in the SSL library occurred, usually a
protocol error. The OpenSSL error queue contains more
information on the error.
SEE ALSOssl(3), err(3)HISTORYSSL_get_error() was added in SSLeay 0.8.
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