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			125 lines
		
	
	
		
			3.9 KiB
		
	
	
	
		
			Plaintext
		
	
	
	
			
		
		
	
	
			125 lines
		
	
	
		
			3.9 KiB
		
	
	
	
		
			Plaintext
		
	
	
	
=pod
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=head1 NAME
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SSL_want, SSL_want_nothing, SSL_want_read, SSL_want_write,
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SSL_want_x509_lookup, SSL_want_retry_verify, SSL_want_async, SSL_want_async_job,
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SSL_want_client_hello_cb - obtain state information 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_want(const SSL *ssl);
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 int SSL_want_nothing(const SSL *ssl);
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 int SSL_want_read(const SSL *ssl);
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 int SSL_want_write(const SSL *ssl);
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 int SSL_want_x509_lookup(const SSL *ssl);
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 int SSL_want_retry_verify(const SSL *ssl);
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 int SSL_want_async(const SSL *ssl);
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 int SSL_want_async_job(const SSL *ssl);
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 int SSL_want_client_hello_cb(const SSL *ssl);
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=head1 DESCRIPTION
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SSL_want() returns state information for the SSL object B<ssl>. B<ssl> B<MUST NOT> be NULL.
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The other SSL_want_*() calls are shortcuts for the possible states returned
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by SSL_want().
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=head1 NOTES
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SSL_want() examines the internal state information of the SSL object. Its
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return values are similar to that of L<SSL_get_error(3)>.
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Unlike L<SSL_get_error(3)>, which also evaluates the
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error queue, the results are obtained by examining an internal state flag
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only. The information must therefore only be used for normal operation under
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nonblocking I/O. Error conditions are not handled and must be treated
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using L<SSL_get_error(3)>.
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The result returned by SSL_want() should always be consistent with
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the result of L<SSL_get_error(3)>.
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=head1 RETURN VALUES
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The following return values can currently occur for SSL_want():
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=over 4
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=item SSL_NOTHING
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There is no data to be written or to be read.
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=item SSL_WRITING
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There are data in the SSL buffer that must be written to the underlying
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B<BIO> layer in order to complete the actual SSL_*() operation.
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A call to L<SSL_get_error(3)> should return B<SSL_ERROR_WANT_WRITE>.
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=item SSL_READING
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More data must be read from the underlying B<BIO> layer in order to
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complete the actual SSL_*() operation.
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A call to L<SSL_get_error(3)> should return B<SSL_ERROR_WANT_READ>.
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=item SSL_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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A call to L<SSL_get_error(3)> should return B<SSL_ERROR_WANT_X509_LOOKUP>.
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=item SSL_RETRY_VERIFY
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The operation did not complete because a certificate verification callback
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has asked to be called again via L<SSL_set_retry_verify(3)>.
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A call to L<SSL_get_error(3)> should return B<SSL_ERROR_WANT_RETRY_VERIFY>.
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=item SSL_ASYNC_PAUSED
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An asynchronous operation partially completed and was then paused. See
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L<SSL_get_all_async_fds(3)>. A call to L<SSL_get_error(3)> should return
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B<SSL_ERROR_WANT_ASYNC>.
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=item SSL_ASYNC_NO_JOBS
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The asynchronous job could not be started because there were no async jobs
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available in the pool (see ASYNC_init_thread(3)). A call to L<SSL_get_error(3)>
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should return B<SSL_ERROR_WANT_ASYNC_JOB>.
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=item SSL_CLIENT_HELLO_CB
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The operation did not complete because an application callback set by
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SSL_CTX_set_client_hello_cb() has asked to be called again.
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A call to L<SSL_get_error(3)> should return B<SSL_ERROR_WANT_CLIENT_HELLO_CB>.
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=back
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SSL_want_nothing(), SSL_want_read(), SSL_want_write(),
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SSL_want_x509_lookup(), SSL_want_retry_verify(),
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SSL_want_async(), SSL_want_async_job(), and SSL_want_client_hello_cb()
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return 1 when the corresponding condition is true or 0 otherwise.
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=head1 QUIC-SPECIFIC CONSIDERATIONS
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For QUIC, these functions relate only to the TLS handshake layer.
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=head1 SEE ALSO
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L<ssl(7)>, L<SSL_get_error(3)>
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=head1 HISTORY
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The SSL_want_client_hello_cb() function and the SSL_CLIENT_HELLO_CB return value
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were added in OpenSSL 1.1.1.
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=head1 COPYRIGHT
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Copyright 2001-2023 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the Apache License 2.0 (the "License").  You may not use
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this file except in compliance with the License.  You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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