doc/ssl/SSL_write.pod - third_party/openssl - Git at Google

 =pod

 =head1 NAME

 SSL_write - write bytes to a TLS/SSL connection

 =head1 SYNOPSIS

  #include <openssl/ssl.h>

  int SSL_write(SSL *ssl, const void *buf, int num);

 =head1 DESCRIPTION

 SSL_write() writes B<num> bytes from the buffer B<buf> into the specified
 B<ssl> connection.

 =head1 NOTES

 If necessary, SSL_write() will negotiate a TLS/SSL session, if
 not already explicitly performed by L<SSL_connect(3)> or
 L<SSL_accept(3)>. If the
 peer requests a re-negotiation, it will be performed transparently during
 the SSL_write() operation. The behaviour of SSL_write() depends on the
 underlying BIO.

 For the transparent negotiation to succeed, the B<ssl> must have been
 initialized to client or server mode. This is being done by calling
 L<SSL_set_connect_state(3)> or SSL_set_accept_state()
 before the first call to an L<SSL_read(3)> or SSL_write() function.

 If the underlying BIO is B<blocking>, SSL_write() will only return, once the
 write operation has been finished or an error occurred, except when a
 renegotiation take place, in which case a SSL_ERROR_WANT_READ may occur.
 This behaviour can be controlled with the SSL_MODE_AUTO_RETRY flag of the
 L<SSL_CTX_set_mode(3)> call.

 If the underlying BIO is B<non-blocking>, SSL_write() will also return,
 when the underlying BIO could not satisfy the needs of SSL_write()
 to continue the operation. In this case a call to
 L<SSL_get_error(3)> with the
 return value of SSL_write() will yield B<SSL_ERROR_WANT_READ> or
 B<SSL_ERROR_WANT_WRITE>. As at any time a re-negotiation is possible, a
 call to SSL_write() can also cause read operations! The calling process
 then must repeat the call after taking appropriate action to satisfy the
 needs of SSL_write(). The action depends on the underlying BIO. When using a
 non-blocking socket, nothing is to be done, but select() can be used to check
 for the required condition. When using a buffering BIO, like a BIO pair, data
 must be written into or retrieved out of the BIO before being able to continue.

 SSL_write() will only return with success, when the complete contents
 of B<buf> of length B<num> has been written. This default behaviour
 can be changed with the SSL_MODE_ENABLE_PARTIAL_WRITE option of
 L<SSL_CTX_set_mode(3)>. When this flag is set,
 SSL_write() will also return with success, when a partial write has been
 successfully completed. In this case the SSL_write() operation is considered
 completed. The bytes are sent and a new SSL_write() operation with a new
 buffer (with the already sent bytes removed) must be started.
 A partial write is performed with the size of a message block, which is
 16kB for SSLv3/TLSv1.

 =head1 WARNING

 When an SSL_write() operation has to be repeated because of
 B<SSL_ERROR_WANT_READ> or B<SSL_ERROR_WANT_WRITE>, it must be repeated
 with the same arguments.

 When calling SSL_write() with num=0 bytes to be sent the behaviour is
 undefined.

 =head1 RETURN VALUES

 The following return values can occur:

 =over 4

 =item E<gt>0

 The write operation was successful, the return value is the number of
 bytes actually written to the TLS/SSL connection.

 =item Z<>0

 The write operation was not successful. Probably the underlying connection
 was closed. Call SSL_get_error() with the return value B<ret> to find out,
 whether an error occurred or the connection was shut down cleanly
 (SSL_ERROR_ZERO_RETURN).

 =item E<lt>0

 The write operation was not successful, because either an error occurred
 or action must be taken by the calling process. Call SSL_get_error() with the
 return value B<ret> to find out the reason.

 =back

 =head1 SEE ALSO

 L<SSL_get_error(3)>, L<SSL_read(3)>,
 L<SSL_CTX_set_mode(3)>, L<SSL_CTX_new(3)>,
 L<SSL_connect(3)>, L<SSL_accept(3)>
 L<SSL_set_connect_state(3)>,
 L<ssl(3)>, L<bio(3)>

 =head1 COPYRIGHT

 Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.

 Licensed under the OpenSSL license (the "License").  You may not use
 this file except in compliance with the License.  You can obtain a copy
 in the file LICENSE in the source distribution or at
 L<https://www.openssl.org/source/license.html>.

 =cut
	=pod

	=head1 NAME

	SSL_write - write bytes to a TLS/SSL connection

	=head1 SYNOPSIS

	#include <openssl/ssl.h>

	int SSL_write(SSL ssl, const void buf, int num);

	=head1 DESCRIPTION

	SSL_write() writes B<num> bytes from the buffer B<buf> into the specified
	B<ssl> connection.

	=head1 NOTES

	If necessary, SSL_write() will negotiate a TLS/SSL session, if
	not already explicitly performed by L<SSL_connect(3)> or
	L<SSL_accept(3)>. If the
	peer requests a re-negotiation, it will be performed transparently during
	the SSL_write() operation. The behaviour of SSL_write() depends on the
	underlying BIO.

	For the transparent negotiation to succeed, the B<ssl> must have been
	initialized to client or server mode. This is being done by calling
	L<SSL_set_connect_state(3)> or SSL_set_accept_state()
	before the first call to an L<SSL_read(3)> or SSL_write() function.

	If the underlying BIO is B<blocking>, SSL_write() will only return, once the
	write operation has been finished or an error occurred, except when a
	renegotiation take place, in which case a SSL_ERROR_WANT_READ may occur.
	This behaviour can be controlled with the SSL_MODE_AUTO_RETRY flag of the
	L<SSL_CTX_set_mode(3)> call.

	If the underlying BIO is B<non-blocking>, SSL_write() will also return,
	when the underlying BIO could not satisfy the needs of SSL_write()
	to continue the operation. In this case a call to
	L<SSL_get_error(3)> with the
	return value of SSL_write() will yield B<SSL_ERROR_WANT_READ> or
	B<SSL_ERROR_WANT_WRITE>. As at any time a re-negotiation is possible, a
	call to SSL_write() can also cause read operations! The calling process
	then must repeat the call after taking appropriate action to satisfy the
	needs of SSL_write(). The action depends on the underlying BIO. When using a
	non-blocking socket, nothing is to be done, but select() can be used to check
	for the required condition. When using a buffering BIO, like a BIO pair, data
	must be written into or retrieved out of the BIO before being able to continue.

	SSL_write() will only return with success, when the complete contents
	of B<buf> of length B<num> has been written. This default behaviour
	can be changed with the SSL_MODE_ENABLE_PARTIAL_WRITE option of
	L<SSL_CTX_set_mode(3)>. When this flag is set,
	SSL_write() will also return with success, when a partial write has been
	successfully completed. In this case the SSL_write() operation is considered
	completed. The bytes are sent and a new SSL_write() operation with a new
	buffer (with the already sent bytes removed) must be started.
	A partial write is performed with the size of a message block, which is
	16kB for SSLv3/TLSv1.

	=head1 WARNING

	When an SSL_write() operation has to be repeated because of
	B<SSL_ERROR_WANT_READ> or B<SSL_ERROR_WANT_WRITE>, it must be repeated
	with the same arguments.

	When calling SSL_write() with num=0 bytes to be sent the behaviour is
	undefined.

	=head1 RETURN VALUES

	The following return values can occur:

	=over 4

	=item E<gt>0

	The write operation was successful, the return value is the number of
	bytes actually written to the TLS/SSL connection.

	=item Z<>0

	The write operation was not successful. Probably the underlying connection
	was closed. Call SSL_get_error() with the return value B<ret> to find out,
	whether an error occurred or the connection was shut down cleanly
	(SSL_ERROR_ZERO_RETURN).

	=item E<lt>0

	The write operation was not successful, because either an error occurred
	or action must be taken by the calling process. Call SSL_get_error() with the
	return value B<ret> to find out the reason.

	=back

	=head1 SEE ALSO

	L<SSL_get_error(3)>, L<SSL_read(3)>,
	L<SSL_CTX_set_mode(3)>, L<SSL_CTX_new(3)>,
	L<SSL_connect(3)>, L<SSL_accept(3)>
	L<SSL_set_connect_state(3)>,
	L<ssl(3)>, L<bio(3)>

	=head1 COPYRIGHT

	Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.

	Licensed under the OpenSSL license (the "License"). You may not use
	this file except in compliance with the License. You can obtain a copy
	in the file LICENSE in the source distribution or at
	L<https://www.openssl.org/source/license.html>.

	=cut