a528d4f0a9
If something was "present in all versions" of SSLeay, or if it was added to a version of SSLeay (and therefore predates OpenSSL), remove mention of it. Documentation history now starts with OpenSSL. Remove mention of all history before OpenSSL 0.9.8, inclusive. Remove all AUTHOR sections. Reviewed-by: Tim Hudson <tjh@openssl.org>
111 lines
4.1 KiB
Plaintext
111 lines
4.1 KiB
Plaintext
=pod
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=head1 NAME
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SSL_get_error - obtain result code for TLS/SSL I/O operation
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=head1 SYNOPSIS
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#include <openssl/ssl.h>
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int SSL_get_error(const SSL *ssl, int ret);
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=head1 DESCRIPTION
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SSL_get_error() returns a result code (suitable for the C "switch"
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statement) for a preceding call to SSL_connect(), SSL_accept(), SSL_do_handshake(),
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SSL_read(), SSL_peek(), or SSL_write() on B<ssl>. The value returned by
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that TLS/SSL I/O function must be passed to SSL_get_error() in parameter
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B<ret>.
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In addition to B<ssl> and B<ret>, SSL_get_error() inspects the
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current thread's OpenSSL error queue. Thus, SSL_get_error() must be
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used in the same thread that performed the TLS/SSL I/O operation, and no
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other OpenSSL function calls should appear in between. The current
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thread's error queue must be empty before the TLS/SSL I/O operation is
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attempted, or SSL_get_error() will not work reliably.
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=head1 RETURN VALUES
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The following return values can currently occur:
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=over 4
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=item SSL_ERROR_NONE
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The TLS/SSL I/O operation completed. This result code is returned
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if and only if B<ret E<gt> 0>.
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=item SSL_ERROR_ZERO_RETURN
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The TLS/SSL connection has been closed. If the protocol version is SSL 3.0
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or TLS 1.0, this result code is returned only if a closure
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alert has occurred in the protocol, i.e. if the connection has been
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closed cleanly. Note that in this case B<SSL_ERROR_ZERO_RETURN>
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does not necessarily indicate that the underlying transport
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has been closed.
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=item SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE
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The operation did not complete; the same TLS/SSL I/O function should be
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called again later. If, by then, the underlying B<BIO> has data
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available for reading (if the result code is B<SSL_ERROR_WANT_READ>)
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or allows writing data (B<SSL_ERROR_WANT_WRITE>), then some TLS/SSL
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protocol progress will take place, i.e. at least part of an TLS/SSL
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record will be read or written. Note that the retry may again lead to
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a B<SSL_ERROR_WANT_READ> or B<SSL_ERROR_WANT_WRITE> condition.
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There is no fixed upper limit for the number of iterations that
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may be necessary until progress becomes visible at application
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protocol level.
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For socket B<BIO>s (e.g. when SSL_set_fd() was used), select() or
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poll() on the underlying socket can be used to find out when the
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TLS/SSL I/O function should be retried.
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Caveat: Any TLS/SSL I/O function can lead to either of
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B<SSL_ERROR_WANT_READ> and B<SSL_ERROR_WANT_WRITE>. In particular,
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SSL_read() or SSL_peek() may want to write data and SSL_write() may want
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to read data. This is mainly because TLS/SSL handshakes may occur at any
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time during the protocol (initiated by either the client or the server);
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SSL_read(), SSL_peek(), and SSL_write() will handle any pending handshakes.
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=item SSL_ERROR_WANT_CONNECT, SSL_ERROR_WANT_ACCEPT
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The operation did not complete; the same TLS/SSL I/O function should be
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called again later. The underlying BIO was not connected yet to the peer
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and the call would block in connect()/accept(). The SSL function should be
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called again when the connection is established. These messages can only
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appear with a BIO_s_connect() or BIO_s_accept() BIO, respectively.
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In order to find out, when the connection has been successfully established,
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on many platforms select() or poll() for writing on the socket file descriptor
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can be used.
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=item SSL_ERROR_WANT_X509_LOOKUP
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The operation did not complete because an application callback set by
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SSL_CTX_set_client_cert_cb() has asked to be called again.
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The TLS/SSL I/O function should be called again later.
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Details depend on the application.
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=item SSL_ERROR_SYSCALL
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Some I/O error occurred. The OpenSSL error queue may contain more
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information on the error. If the error queue is empty
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(i.e. ERR_get_error() returns 0), B<ret> can be used to find out more
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about the error: If B<ret == 0>, an EOF was observed that violates
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the protocol. If B<ret == -1>, the underlying B<BIO> reported an
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I/O error (for socket I/O on Unix systems, consult B<errno> for details).
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=item SSL_ERROR_SSL
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A failure in the SSL library occurred, usually a protocol error. The
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OpenSSL error queue contains more information on the error.
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=back
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=head1 SEE ALSO
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L<ssl(3)>, L<err(3)>
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=cut
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