MirBSD manpage: SSL_get_error(3)

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(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 tran-
         sport 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.

MirBSD #10-current         2005-04-29                           1

SSL_GET_ERROR(3)             OpenSSL             SSL_GET_ERROR(3)

         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 par-
         ticular, 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 proto-
         col error.  The OpenSSL error queue contains more infor-
         mation on the error.

SEE ALSO

     ssl(3), err(3)

HISTORY

     SSL_get_error() was added in SSLeay 0.8.

MirBSD #10-current         2005-04-29                           2