crypto/armcap.c: fix typo in rdtsc subroutine.

[openssl.git] / doc / ssl / SSL_write.pod

diff --git a/doc/ssl/SSL_write.pod b/doc/ssl/SSL_write.pod
index 4db85473d9a9c552848f07f5c4616d8f3b9f1bb8..e013c12d5254b0d4d08bb0d6ef47972994b72ada 100644 (file)
--- a/doc/ssl/SSL_write.pod
+++ b/doc/ssl/SSL_write.pod
@@ -2,38 +2,72 @@
 
 =head1 NAME
 
 
 =head1 NAME
 

-SSL_read - write bytes to a TLS/SSL connection.
+SSL_write - write bytes to a TLS/SSL connection.

 
 =head1 SYNOPSIS
 
  #include <openssl/ssl.h>
 
 
 =head1 SYNOPSIS
 
  #include <openssl/ssl.h>
 

- int SSL_write(SSL *ssl, char *buf, int num);
+ 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
 
 =head1 DESCRIPTION
 
 SSL_write() writes B<num> bytes from the buffer B<buf> into the specified

-B<ssl>. If necessary, SSL_write() will negotiate a TLS/SSL session, if
-not already explicitly performed by SSL_connect() or SSL_accept(). If the
+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)|SSL_connect(3)> or
+L<SSL_accept(3)|SSL_accept(3)>. If the

 peer requests a re-negotiation, it will be performed transparently during
 peer requests a re-negotiation, it will be performed transparently during

-the SSL_write() operation. The behavior of SSL_write() depends on the
+the SSL_write() operation. The behaviour of SSL_write() depends on the

 underlying BIO. 
 
 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)|SSL_set_connect_state(3)> or SSL_set_accept_state()
+before the first call to an L<SSL_read(3)|SSL_read(3)> or SSL_write() function.
+

 If the underlying BIO is B<blocking>, SSL_write() will only return, once the
 If the underlying BIO is B<blocking>, SSL_write() will only return, once the

-write operation has been finished or an error occurred.
+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)|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()
 
 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 SSL_get_error() with the
+to continue the operation. In this case a call to
+L<SSL_get_error(3)|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
 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 write operations! The calling process
+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.
 
 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)|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:
 =head1 RETURN VALUES
 
 The following return values can occur:


@@ -47,12 +81,18 @@ bytes actually written to the TLS/SSL connection.
 
 =item 0
 
 
 =item 0
 

-The write operation was not successful. Call SSL_get_error() with the return
-value B<ret> to find out, whether an error occurred.
+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).
+
+SSLv2 (deprecated) does not support a shutdown alert protocol, so it can
+only be detected, whether the underlying connection was closed. It cannot
+be checked, why the closure happened.

 
 

-=item -1
+=item E<lt>0

 
 

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


@@ -61,6 +101,9 @@ return value B<ret> to find out the reason.
 =head1 SEE ALSO
 
 L<SSL_get_error(3)|SSL_get_error(3)>, L<SSL_read(3)|SSL_read(3)>,
 =head1 SEE ALSO
 
 L<SSL_get_error(3)|SSL_get_error(3)>, L<SSL_read(3)|SSL_read(3)>,

+L<SSL_CTX_set_mode(3)|SSL_CTX_set_mode(3)>, L<SSL_CTX_new(3)|SSL_CTX_new(3)>,
+L<SSL_connect(3)|SSL_connect(3)>, L<SSL_accept(3)|SSL_accept(3)>
+L<SSL_set_connect_state(3)|SSL_set_connect_state(3)>,

 L<ssl(3)|ssl(3)>, L<bio(3)|bio(3)>
 
 =cut
 L<ssl(3)|ssl(3)>, L<bio(3)|bio(3)>
 
 =cut