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" 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.