Provided by: libssl-doc_1.0.1-4ubuntu3_all bug

NAME

       SSL_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);

DESCRIPTION

       SSL_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 ALSO

       ssl(3), err(3)

HISTORY

       SSL_get_error() was added in SSLeay 0.8.