Provide documentation for all SSL(_CTX)?_(get|set)(_default)?_read_ahead

functions.
Reviewed-by: NAndy Polyakov <appro@openssl.org>

doc/ssl/SSL_CTX_set_read_ahead.pod

+=pod
+
+=head1 NAME
+
+SSL_CTX_set_read_ahead, SSL_CTX_set_default_read_ahead, SSL_CTX_get_read_ahead,
+SSL_CTX_get_default_read_ahead, SSL_set_read_ahead, SSL_get_read_ahead
+- manage whether to read as many input bytes as possible
+
+=head1 SYNOPSIS
+
+ #include <openssl/ssl.h>
+
+ int SSL_get_read_ahead(const SSL *s);
+ void SSL_set_read_ahead(SSL *s, int yes);
+
+ #define SSL_CTX_get_default_read_ahead(ctx)
+ #define SSL_CTX_set_default_read_ahead(ctx,m)
+ #define SSL_CTX_get_read_ahead(ctx)
+ #define SSL_CTX_set_read_ahead(ctx,m)
+
+=head1 DESCRIPTION
+
+SSL_CTX_set_read_ahead() and SSL_set_read_ahead() set whether we should read as
+many input bytes as possible (for non-blocking reads) or not. For example if
+B<x> bytes are currently required by OpenSSL, but B<y> bytes are available from
+the underlying BIO (where B<y> > B<x>), then OpenSSL will read all B<y> bytes
+into its buffer (providing that the buffer is large enough) if reading ahead is
+on, or B<x> bytes otherwise. The parameter B<yes> or B<m> should be 0 to ensure
+reading ahead is off, or non zero otherwise.
+
+SSL_CTX_set_default_read_ahead is a synonym for SSL_CTX_set_read_ahead, and
+SSL_CTX_get_default_read_ahead is a synonym for SSL_CTX_get_read_ahead.
+
+SSL_CTX_get_read_ahead() and SSL_get_read_ahead() indicate whether reading
+ahead has been set or not.
+
+=head1 NOTES
+
+These functions have no impact when used with DTLS. The return values for
+SSL_CTX_get_read_head() and SSL_get_read_ahead() are undefined for DTLS.
+
+=head1 RETURN VALUES
+
+SSL_get_read_ahead and SSL_CTX_get_read_ahead return 0 if reading ahead is off,
+and non zero otherwise.
+
+=head1 SEE ALSO
+
+L<ssl(3)|ssl(3)>
+
+=cut

doc/ssl/SSL_pending.pod

@@ -29,8 +29,9 @@ The number of bytes pending is returned.
 
 SSL_pending() takes into account only bytes from the TLS/SSL record
 that is currently being processed (if any).  If the B<SSL> object's
-I<read_ahead> flag is set, additional protocol bytes may have been
-read containing more TLS/SSL records; these are ignored by
+I<read_ahead> flag is set (see
+L<SSL_CTX_set_read_ahead(3)|SSL_CTX_set_read_ahead(3)>), additional protocol
+bytes may have been read containing more TLS/SSL records; these are ignored by
 SSL_pending().
 
 Up to OpenSSL 0.9.6, SSL_pending() does not check if the record type
@@ -38,6 +39,7 @@ of pending data is application data.
 
 =head1 SEE ALSO
 
-L<SSL_read(3)|SSL_read(3)>, L<ssl(3)|ssl(3)>
+L<SSL_read(3)|SSL_read(3)>,
+L<SSL_CTX_set_read_ahead(3)|SSL_CTX_set_read_ahead(3)>, L<ssl(3)|ssl(3)>
 
 =cut

doc/ssl/ssl.pod

@@ -217,6 +217,8 @@ protocol context defined in the B<SSL_CTX> structure.
 
 =item int (*B<SSL_CTX_get_client_cert_cb>(SSL_CTX *ctx))(SSL *ssl, X509 **x509, EVP_PKEY **pkey);
 
+=item void B<SSL_CTX_get_default_read_ahead>(SSL_CTX *ctx);
+
 =item char *B<SSL_CTX_get_ex_data>(const SSL_CTX *s, int idx);
 
 =item int B<SSL_CTX_get_ex_new_index>(long argl, char *argp, int (*new_func);(void), int (*dup_func)(void), void (*free_func)(void))
@@ -225,6 +227,8 @@ protocol context defined in the B<SSL_CTX> structure.
 
 =item int B<SSL_CTX_get_quiet_shutdown>(const SSL_CTX *ctx);
 
+=item void B<SSL_CTX_get_read_ahead>(SSL_CTX *ctx);
+
 =item int B<SSL_CTX_get_session_cache_mode>(SSL_CTX *ctx);
 
 =item long B<SSL_CTX_get_timeout>(const SSL_CTX *ctx);
@@ -313,6 +317,8 @@ protocol context defined in the B<SSL_CTX> structure.
 
 =item void B<SSL_CTX_set_quiet_shutdown>(SSL_CTX *ctx, int mode);
 
+=item void B<SSL_CTX_set_read_ahead>(SSL_CTX *ctx, int m);
+
 =item void B<SSL_CTX_set_session_cache_mode>(SSL_CTX *ctx, int mode);
 
 =item int B<SSL_CTX_set_ssl_version>(SSL_CTX *ctx, const SSL_METHOD *meth);
@@ -695,6 +701,7 @@ L<SSL_CTX_set_mode(3)|SSL_CTX_set_mode(3)>,
 L<SSL_CTX_set_msg_callback(3)|SSL_CTX_set_msg_callback(3)>,
 L<SSL_CTX_set_options(3)|SSL_CTX_set_options(3)>,
 L<SSL_CTX_set_quiet_shutdown(3)|SSL_CTX_set_quiet_shutdown(3)>,
+L<SSL_CTX_set_read_ahead(3)|SSL_CTX_set_read_ahead(3)>,
 L<SSL_CTX_set_session_cache_mode(3)|SSL_CTX_set_session_cache_mode(3)>,
 L<SSL_CTX_set_session_id_context(3)|SSL_CTX_set_session_id_context(3)>,
 L<SSL_CTX_set_ssl_version(3)|SSL_CTX_set_ssl_version(3)>,