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(const 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_do_handshake(), SSL_read(), SSL_peek(), 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. 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),
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 SSL_ERROR_WANT_READ or
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 BIOs (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
SSL_ERROR_WANT_READ and 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.
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_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.
1.0.1f 2014-01-06 SSL_get_error(3)
