Added support for the Snappy compression algorithm

Added support for the Snappy compression algorithm which has shown to
have considerably better compression speed than LZO at a comparable
compression ratio.

To enable Snappy add:

  compress snappy

to both client and server config files.

Alternatively, enable compression framing on the client:

  compress

and have the server selectively push "compress snappy" to the client.

This change also extends the client capability handshake to include
IV_SNAPPY so the server can be aware that a connecting client supports
Snappy.

Note that the Snappy implementation also includes an improved framing
approach where the first byte of the compressed payload is replaced by
the compression control byte (the first payload byte is moved to the end
of the packet).  This solves off-by-one alignment issues, which improves
performance on ARM.

By default, the configure script will try to build with Snappy support.
To disable, use the --disable-snappy option.

The --enable-lzo-stub configure directive is now --enable-comp-stub
(because it's not actually "lzo" but "compression-enabled packet framing")

Add compression overhead to extra buffer unconditionally, as long
as USE_COMP is defined.

OpenVPN SVN r8206 (2.1.21a) and r8212 (2.1.21b)

Signed-off-by: Gert Doering <gert@greenie.muc.de>
Acked-by: Arne Schwabe <arne@rfc2549.org>
Message-Id: <1366393268-27392-3-git-send-email-gert@greenie.muc.de>
URL: http://article.gmane.org/gmane.network.openvpn.devel/7531
Signed-off-by: Gert Doering <gert@greenie.muc.de>

1 files changed, 39 insertions, 0 deletions

diff --git a/src/openvpn/snappy.h b/src/openvpn/snappy.h
new file mode 100644
index 0000000..361a631
--- /dev/null
+++ b/src/openvpn/snappy.h
@@ -0,0 +1,39 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2012 OpenVPN Technologies, Inc. <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program (see the file COPYING included with this
+ *  distribution); if not, write to the Free Software Foundation, Inc.,
+ *  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#ifndef OPENVPN_SNAPPY_H
+#define OPENVPN_SNAPPY_H
+
+#if defined(ENABLE_SNAPPY)
+
+#include "buffer.h"
+
+extern const struct compress_alg snappy_alg;
+
+struct snappy_workspace
+{
+};
+
+#endif /* ENABLE_SNAPPY */
+#endif