- NAME
- SYNOPSIS
- DESCRIPTION
- RETURN VALUES
- SEE ALSO
- HISTORY

# 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, err

# HISTORY

`SSL_get_error()` was added in SSLeay 0.8.