1*2175Sjp161948=pod 2*2175Sjp161948 3*2175Sjp161948=head1 NAME 4*2175Sjp161948 5*2175Sjp161948SSL_get_error - obtain result code for TLS/SSL I/O operation 6*2175Sjp161948 7*2175Sjp161948=head1 SYNOPSIS 8*2175Sjp161948 9*2175Sjp161948 #include <openssl/ssl.h> 10*2175Sjp161948 11*2175Sjp161948 int SSL_get_error(const SSL *ssl, int ret); 12*2175Sjp161948 13*2175Sjp161948=head1 DESCRIPTION 14*2175Sjp161948 15*2175Sjp161948SSL_get_error() returns a result code (suitable for the C "switch" 16*2175Sjp161948statement) for a preceding call to SSL_connect(), SSL_accept(), SSL_do_handshake(), 17*2175Sjp161948SSL_read(), SSL_peek(), or SSL_write() on B<ssl>. The value returned by 18*2175Sjp161948that TLS/SSL I/O function must be passed to SSL_get_error() in parameter 19*2175Sjp161948B<ret>. 20*2175Sjp161948 21*2175Sjp161948In addition to B<ssl> and B<ret>, SSL_get_error() inspects the 22*2175Sjp161948current thread's OpenSSL error queue. Thus, SSL_get_error() must be 23*2175Sjp161948used in the same thread that performed the TLS/SSL I/O operation, and no 24*2175Sjp161948other OpenSSL function calls should appear in between. The current 25*2175Sjp161948thread's error queue must be empty before the TLS/SSL I/O operation is 26*2175Sjp161948attempted, or SSL_get_error() will not work reliably. 27*2175Sjp161948 28*2175Sjp161948=head1 RETURN VALUES 29*2175Sjp161948 30*2175Sjp161948The following return values can currently occur: 31*2175Sjp161948 32*2175Sjp161948=over 4 33*2175Sjp161948 34*2175Sjp161948=item SSL_ERROR_NONE 35*2175Sjp161948 36*2175Sjp161948The TLS/SSL I/O operation completed. This result code is returned 37*2175Sjp161948if and only if B<ret E<gt> 0>. 38*2175Sjp161948 39*2175Sjp161948=item SSL_ERROR_ZERO_RETURN 40*2175Sjp161948 41*2175Sjp161948The TLS/SSL connection has been closed. If the protocol version is SSL 3.0 42*2175Sjp161948or TLS 1.0, this result code is returned only if a closure 43*2175Sjp161948alert has occurred in the protocol, i.e. if the connection has been 44*2175Sjp161948closed cleanly. Note that in this case B<SSL_ERROR_ZERO_RETURN> 45*2175Sjp161948does not necessarily indicate that the underlying transport 46*2175Sjp161948has been closed. 47*2175Sjp161948 48*2175Sjp161948=item SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE 49*2175Sjp161948 50*2175Sjp161948The operation did not complete; the same TLS/SSL I/O function should be 51*2175Sjp161948called again later. If, by then, the underlying B<BIO> has data 52*2175Sjp161948available for reading (if the result code is B<SSL_ERROR_WANT_READ>) 53*2175Sjp161948or allows writing data (B<SSL_ERROR_WANT_WRITE>), then some TLS/SSL 54*2175Sjp161948protocol progress will take place, i.e. at least part of an TLS/SSL 55*2175Sjp161948record will be read or written. Note that the retry may again lead to 56*2175Sjp161948a B<SSL_ERROR_WANT_READ> or B<SSL_ERROR_WANT_WRITE> condition. 57*2175Sjp161948There is no fixed upper limit for the number of iterations that 58*2175Sjp161948may be necessary until progress becomes visible at application 59*2175Sjp161948protocol level. 60*2175Sjp161948 61*2175Sjp161948For socket B<BIO>s (e.g. when SSL_set_fd() was used), select() or 62*2175Sjp161948poll() on the underlying socket can be used to find out when the 63*2175Sjp161948TLS/SSL I/O function should be retried. 64*2175Sjp161948 65*2175Sjp161948Caveat: Any TLS/SSL I/O function can lead to either of 66*2175Sjp161948B<SSL_ERROR_WANT_READ> and B<SSL_ERROR_WANT_WRITE>. In particular, 67*2175Sjp161948SSL_read() or SSL_peek() may want to write data and SSL_write() may want 68*2175Sjp161948to read data. This is mainly because TLS/SSL handshakes may occur at any 69*2175Sjp161948time during the protocol (initiated by either the client or the server); 70*2175Sjp161948SSL_read(), SSL_peek(), and SSL_write() will handle any pending handshakes. 71*2175Sjp161948 72*2175Sjp161948=item SSL_ERROR_WANT_CONNECT, SSL_ERROR_WANT_ACCEPT 73*2175Sjp161948 74*2175Sjp161948The operation did not complete; the same TLS/SSL I/O function should be 75*2175Sjp161948called again later. The underlying BIO was not connected yet to the peer 76*2175Sjp161948and the call would block in connect()/accept(). The SSL function should be 77*2175Sjp161948called again when the connection is established. These messages can only 78*2175Sjp161948appear with a BIO_s_connect() or BIO_s_accept() BIO, respectively. 79*2175Sjp161948In order to find out, when the connection has been successfully established, 80*2175Sjp161948on many platforms select() or poll() for writing on the socket file descriptor 81*2175Sjp161948can be used. 82*2175Sjp161948 83*2175Sjp161948=item SSL_ERROR_WANT_X509_LOOKUP 84*2175Sjp161948 85*2175Sjp161948The operation did not complete because an application callback set by 86*2175Sjp161948SSL_CTX_set_client_cert_cb() has asked to be called again. 87*2175Sjp161948The TLS/SSL I/O function should be called again later. 88*2175Sjp161948Details depend on the application. 89*2175Sjp161948 90*2175Sjp161948=item SSL_ERROR_SYSCALL 91*2175Sjp161948 92*2175Sjp161948Some I/O error occurred. The OpenSSL error queue may contain more 93*2175Sjp161948information on the error. If the error queue is empty 94*2175Sjp161948(i.e. ERR_get_error() returns 0), B<ret> can be used to find out more 95*2175Sjp161948about the error: If B<ret == 0>, an EOF was observed that violates 96*2175Sjp161948the protocol. If B<ret == -1>, the underlying B<BIO> reported an 97*2175Sjp161948I/O error (for socket I/O on Unix systems, consult B<errno> for details). 98*2175Sjp161948 99*2175Sjp161948=item SSL_ERROR_SSL 100*2175Sjp161948 101*2175Sjp161948A failure in the SSL library occurred, usually a protocol error. The 102*2175Sjp161948OpenSSL error queue contains more information on the error. 103*2175Sjp161948 104*2175Sjp161948=back 105*2175Sjp161948 106*2175Sjp161948=head1 SEE ALSO 107*2175Sjp161948 108*2175Sjp161948L<ssl(3)|ssl(3)>, L<err(3)|err(3)> 109*2175Sjp161948 110*2175Sjp161948=head1 HISTORY 111*2175Sjp161948 112*2175Sjp161948SSL_get_error() was added in SSLeay 0.8. 113*2175Sjp161948 114*2175Sjp161948=cut 115