SSL_get_error(3)

NAME
SSL_get_error - obtain result code for SSL I/O operation

LIBRARY
libcrypto, -lcrypto

SYNOPSIS

 #include <openssl/ssl.h>
 int SSL_get_error(SSL *ssl, int ret);

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 ssl. The value returned by that 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 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 SSL I/O operation is attempted, or SSL_get_error() will not work reliably.

RETURN VALUES
The following return values can currently occur: The SSL I/O operation completed. This result code is returned if and only if ret > 0. The 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 occurred in the protocol, i.e. if the connection has been closed cleanly. 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 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 SSL I/O function should be retried.

Caveat: Any SSL I/O function can lead to either of 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. 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. Details depend on the application. 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). A failure in the SSL library occurred, usually a protocol error. The OpenSSL error queue contains more information on the error.

SEE ALSO
the ssl(3)|ssl(3) manpage, the err(3)|err(3) manpage

HISTORY
SSL_get_error() was added in SSLeay 0.8.