Describe new callback for session id generation.

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

diff --git a/doc/ssl/SSL_read.pod b/doc/ssl/SSL_read.pod
index 9df51030c58846d3ceb8984b833b622ae9a7c4fc..ed86d269dcd694f4d3c3a5241a453fcd49b3dc88 100644 (file)
--- a/doc/ssl/SSL_read.pod
+++ b/doc/ssl/SSL_read.pod
@@ -2,7 +2,7 @@
 
 =head1 NAME
 
-SSL_read - Read bytes from a TLS connection.
+SSL_read - read bytes from a TLS/SSL connection.
 
 =head1 SYNOPSIS
 
@@ -13,20 +13,27 @@ SSL_read - Read bytes from a TLS connection.
 =head1 DESCRIPTION
 
 SSL_read() tries to read B<num> bytes from the specified B<ssl> into the
-buffer B<buf>. If necessary, SSL_read() will negotiate a TLS session, if
-not already explicitely performed by SSL_connect() or SSL_accept(). If the
+buffer B<buf>.
+
+=head1 NOTES
+
+If necessary, SSL_read() will negotiate a TLS/SSL session, if
+not already explicitly performed by SSL_connect() or SSL_accept(). If the
 peer requests a re-negotiation, it will be performed transparently during
 the SSL_read() operation. The behaviour of SSL_read() depends on the
 underlying BIO. 
 
 If the underlying BIO is B<blocking>, SSL_read() will only return, once the
-read operation has been finished or an error occured.
+read 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_read() will also return,
+If the underlying BIO is B<non-blocking>, SSL_read() will also return
 when the underlying BIO could not satisfy the needs of SSL_read()
 to continue the operation. In this case a call to SSL_get_error() with the
-return value of SSL_read() will yield SSL_ERROR_WANT_READ or
-SSL_ERROR_WANT_WRITE. As at any time a re-negotiation is possible, a
+return value of SSL_read() 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_read() can also cause write operations! The calling process
 then must repeat the call after taking appropriate action to satisfy the
 needs of SSL_read(). The action depends on the underlying BIO. When using a
@@ -34,6 +41,12 @@ 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.
 
+=head1 WARNING
+
+When an SSL_read() 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.
+
 =head1 RETURN VALUES
 
 The following return values can occur:
@@ -42,18 +55,18 @@ The following return values can occur:
 
 =item E<gt>0
 
-The read operation was successfull, the return value is the number of
-bytes actually read from the TLS connection.
+The read operation was successful; the return value is the number of
+bytes actually read from the TLS/SSL connection.
 
 =item 0
 
-The read operation was not successfull, probably because no data was
+The read operation was not successful, probably because no data was
 available. Call SSL_get_error() with the return value B<ret> to find out,
-whether an error occured.
+whether an error occurred.
 
-=item -1
+=item E<lt>0
 
-The read operation was not successfull, because either an error occured
+The read 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.
 
@@ -62,6 +75,7 @@ return value B<ret> to find out the reason.
 =head1 SEE ALSO
 
 L<SSL_get_error(3)|SSL_get_error(3)>, L<SSL_write(3)|SSL_write(3)>,
+L<SSL_CTX_set_mode(3)|SSL_CTX_set_mode(3)>,
 L<ssl(3)|ssl(3)>, L<bio(3)|bio(3)>
 
 =cut