SSL_get_error(3) OpenSSL SSL_get_error(3) NAME SSL_get_error - obtain result code for TLS/SSL I/O operation 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(1,n)" 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(1,8) parameter ret. In addition to ssl and ret, SSL_get_error() inspects the current thread's OpenSSL error(8,n) queue. Thus, SSL_get_error() must be used in(1,8) the same thread that performed the TLS/SSL I/O operation, and no other OpenSSL function calls should appear in(1,8) between. The current thread's error(8,n) queue(1,3) 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(3,n) and only if(3,n) ret > 0. SSL_ERROR_ZERO_RETURN The TLS/SSL connection has been closed. If the protocol version(1,3,5) is SSL 3.0 or TLS 1.0, this result code is returned only if(3,n) a closure alert has occurred in(1,8) the protocol, i.e. if(3,n) the connection has been closed cleanly. Note that in(1,8) 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(3,n) 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(2,n,1 builtins) 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(2,7,n) BIOs (e.g. when SSL_set_fd() was used), select(2,7,2 select_tut)() or poll() on the underlying socket(2,7,n) 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(1,2) data and SSL_write() may want to read(2,n,1 builtins) data. This is mainly because TLS/SSL handshakes may occur at any time(1,2,n) 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(1,8) connect()/accept(2,8)(). The SSL function should be called again when the connection is estab- lished. 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(2,7,2 select_tut)() or poll() for writing on the socket(2,7,n) file(1,n) descriptor can be used. SSL_ERROR_WANT_X509_LOOKUP The operation did not complete because an application callback set(7,n,1 builtins) 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(8,n) occurred. The OpenSSL error(8,n) queue(1,3) may contain more information on the error. If the error(8,n) queue(1,3) 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 pro- tocol. If ret == -1, the underlying BIO reported an I/O error(8,n) (for socket(2,7,n) I/O on Unix systems, consult errno for details). SSL_ERROR_SSL A failure in(1,8) the SSL library occurred, usually a protocol error. The OpenSSL error(8,n) queue(1,3) contains more information on the error. SEE ALSO ssl(3), err(3) HISTORY SSL_get_error() was added in(1,8) SSLeay 0.8. 0.9.7d 2002-07-29 SSL_get_error(3)