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, 51 insertions, 103 deletions

diff --git a/src/openvpn/lzo.c b/src/openvpn/lzo.c
index 195b819..daa02ed 100644
--- a/src/openvpn/lzo.c
+++ b/src/openvpn/lzo.c
@@ -34,15 +34,17 @@
 
 #include "syshead.h"
 
-#ifdef ENABLE_LZO
+#if defined(ENABLE_LZO)
 
-#include "lzo.h"
+#include "comp.h"
 #include "error.h"
 #include "otime.h"
 
 #include "memdbg.h"
 
-#ifndef ENABLE_LZO_STUB
+/* Initial command byte to tell our peer if we compressed */
+#define LZO_COMPRESS_BYTE 0x66
+
 /**
  * Perform adaptive compression housekeeping.
  *
@@ -97,101 +99,69 @@ lzo_adaptive_compress_data (struct lzo_adaptive_compress *ac, int n_total, int n
   ac->n_comp += n_comp;
 }
 
-#endif /* ENABLE_LZO_STUB */
-
-void lzo_adjust_frame_parameters (struct frame *frame)
-{
-  /* Leave room for our one-byte compressed/didn't-compress prefix byte. */
-  frame_add_to_extra_frame (frame, LZO_PREFIX_LEN);
-
-  /* Leave room for compression buffer to expand in worst case scenario
-     where data is totally uncompressible */
-  frame_add_to_extra_buffer (frame, LZO_EXTRA_BUFFER (EXPANDED_SIZE(frame)));
-}
-
-void
-lzo_compress_init (struct lzo_compress_workspace *lzowork, unsigned int flags)
+static void
+lzo_compress_init (struct compress_context *compctx)
 {
-  CLEAR (*lzowork);
-
-  lzowork->flags = flags;
-#ifndef ENABLE_LZO_STUB
-  lzowork->wmem_size = LZO_WORKSPACE;
-
+  msg (D_INIT_MEDIUM, "LZO compression initializing");
+  ASSERT(!(compctx->flags & COMP_F_SWAP));
+  compctx->wu.lzo.wmem_size = LZO_WORKSPACE;
   if (lzo_init () != LZO_E_OK)
     msg (M_FATAL, "Cannot initialize LZO compression library");
-  lzowork->wmem = (lzo_voidp) lzo_malloc (lzowork->wmem_size);
-  check_malloc_return (lzowork->wmem);
-  msg (D_INIT_MEDIUM, "LZO compression initialized");
-#else
-  msg (D_INIT_MEDIUM, "LZO stub compression initialized");
-#endif
-  lzowork->defined = true;
+  compctx->wu.lzo.wmem = (lzo_voidp) lzo_malloc (compctx->wu.lzo.wmem_size);
+  check_malloc_return (compctx->wu.lzo.wmem);
 }
 
-void
-lzo_compress_uninit (struct lzo_compress_workspace *lzowork)
+static void
+lzo_compress_uninit (struct compress_context *compctx)
 {
-  if (lzowork)
-    {
-      ASSERT (lzowork->defined);
-#ifndef ENABLE_LZO_STUB
-      lzo_free (lzowork->wmem);
-      lzowork->wmem = NULL;
-#endif
-      lzowork->defined = false;
-    }
+  lzo_free (compctx->wu.lzo.wmem);
+  compctx->wu.lzo.wmem = NULL;
 }
 
 static inline bool
-lzo_compression_enabled (struct lzo_compress_workspace *lzowork)
+lzo_compression_enabled (struct compress_context *compctx)
 {
-#ifndef ENABLE_LZO_STUB
-  if ((lzowork->flags & (LZO_SELECTED|LZO_ON)) == (LZO_SELECTED|LZO_ON))
+  if (compctx->flags & COMP_F_ASYM)
+    return false;
+  else
     {
-      if (lzowork->flags & LZO_ADAPTIVE)
-	return lzo_adaptive_compress_test (&lzowork->ac);
+      if (compctx->flags & COMP_F_ADAPTIVE)
+	return lzo_adaptive_compress_test (&compctx->wu.lzo.ac);
       else
 	return true;
     }
-#endif
-  return false;
 }
 
-void
+static void
 lzo_compress (struct buffer *buf, struct buffer work,
-	      struct lzo_compress_workspace *lzowork,
+	      struct compress_context *compctx,
 	      const struct frame* frame)
 {
-#ifndef ENABLE_LZO_STUB
   lzo_uint zlen = 0;
   int err;
   bool compressed = false;
-#endif
-
-  ASSERT (lzowork->defined);
 
   if (buf->len <= 0)
     return;
 
-#ifndef ENABLE_LZO_STUB
   /*
    * In order to attempt compression, length must be at least COMPRESS_THRESHOLD,
    * and our adaptive level must give the OK.
    */
-  if (buf->len >= COMPRESS_THRESHOLD && lzo_compression_enabled (lzowork))
+  if (buf->len >= COMPRESS_THRESHOLD && lzo_compression_enabled (compctx))
     {
+      const size_t ps = PAYLOAD_SIZE (frame);
       ASSERT (buf_init (&work, FRAME_HEADROOM (frame)));
-      ASSERT (buf_safe (&work, LZO_EXTRA_BUFFER (PAYLOAD_SIZE (frame))));
+      ASSERT (buf_safe (&work, ps + COMP_EXTRA_BUFFER (ps)));
 
-      if (!(buf->len <= PAYLOAD_SIZE (frame)))
+      if (buf->len > ps)
 	{
 	  dmsg (D_COMP_ERRORS, "LZO compression buffer overflow");
 	  buf->len = 0;
 	  return;
 	}
 
-      err = LZO_COMPRESS (BPTR (buf), BLEN (buf), BPTR (&work), &zlen, lzowork->wmem);
+      err = LZO_COMPRESS (BPTR (buf), BLEN (buf), BPTR (&work), &zlen, compctx->wu.lzo.wmem);
       if (err != LZO_E_OK)
 	{
 	  dmsg (D_COMP_ERRORS, "LZO compression error: %d", err);
@@ -203,43 +173,38 @@ lzo_compress (struct buffer *buf, struct buffer work,
       work.len = zlen;
       compressed = true;
 
-      dmsg (D_COMP, "compress %d -> %d", buf->len, work.len);
-      lzowork->pre_compress += buf->len;
-      lzowork->post_compress += work.len;
+      dmsg (D_COMP, "LZO compress %d -> %d", buf->len, work.len);
+      compctx->pre_compress += buf->len;
+      compctx->post_compress += work.len;
 
       /* tell adaptive level about our success or lack thereof in getting any size reduction */
-      if (lzowork->flags & LZO_ADAPTIVE)
-	lzo_adaptive_compress_data (&lzowork->ac, buf->len, work.len);
+      if (compctx->flags & COMP_F_ADAPTIVE)
+	lzo_adaptive_compress_data (&compctx->wu.lzo.ac, buf->len, work.len);
     }
 
   /* did compression save us anything ? */
   if (compressed && work.len < buf->len)
     {
       uint8_t *header = buf_prepend (&work, 1);
-      *header = YES_COMPRESS;
+      *header = LZO_COMPRESS_BYTE;
       *buf = work;
     }
   else
-#endif
     {
       uint8_t *header = buf_prepend (buf, 1);
-      *header = NO_COMPRESS;
+      *header = NO_COMPRESS_BYTE;
     }
 }
 
-void
+static void
 lzo_decompress (struct buffer *buf, struct buffer work,
-		struct lzo_compress_workspace *lzowork,
+		struct compress_context *compctx,
 		const struct frame* frame)
 {
-#ifndef ENABLE_LZO_STUB
   lzo_uint zlen = EXPANDED_SIZE (frame);
   int err;
-#endif
   uint8_t c;		/* flag indicating whether or not our peer compressed */
 
-  ASSERT (lzowork->defined);
-
   if (buf->len <= 0)
     return;
 
@@ -248,12 +213,11 @@ lzo_decompress (struct buffer *buf, struct buffer work,
   c = *BPTR (buf);
   ASSERT (buf_advance (buf, 1));
 
-  if (c == YES_COMPRESS)	/* packet was compressed */
+  if (c == LZO_COMPRESS_BYTE)	/* packet was compressed */
     {
-#ifndef ENABLE_LZO_STUB
       ASSERT (buf_safe (&work, zlen));
       err = LZO_DECOMPRESS (BPTR (buf), BLEN (buf), BPTR (&work), &zlen,
-			    lzowork->wmem);
+			    compctx->wu.lzo.wmem);
       if (err != LZO_E_OK)
 	{
 	  dmsg (D_COMP_ERRORS, "LZO decompression error: %d", err);
@@ -264,18 +228,13 @@ lzo_decompress (struct buffer *buf, struct buffer work,
       ASSERT (buf_safe (&work, zlen));
       work.len = zlen;
 
-      dmsg (D_COMP, "decompress %d -> %d", buf->len, work.len);
-      lzowork->pre_decompress += buf->len;
-      lzowork->post_decompress += work.len;
+      dmsg (D_COMP, "LZO decompress %d -> %d", buf->len, work.len);
+      compctx->pre_decompress += buf->len;
+      compctx->post_decompress += work.len;
 
       *buf = work;
-#else
-      dmsg (D_COMP_ERRORS, "LZO decompression error: LZO capability not compiled");
-      buf->len = 0;
-      return;
-#endif
     }
-  else if (c == NO_COMPRESS)	/* packet was not compressed */
+  else if (c == NO_COMPRESS_BYTE)	/* packet was not compressed */
     {
       ;
     }
@@ -286,24 +245,13 @@ lzo_decompress (struct buffer *buf, struct buffer work,
     }
 }
 
-void
-lzo_modify_flags (struct lzo_compress_workspace *lzowork, unsigned int flags)
-{
-  ASSERT (lzowork->defined);
-  lzowork->flags = flags;
-}
-
-void lzo_print_stats (const struct lzo_compress_workspace *lzo_compwork, struct status_output *so)
-{
-  ASSERT (lzo_compwork->defined);
-
-#ifndef ENABLE_LZO_STUB
-  status_printf (so, "pre-compress bytes," counter_format, lzo_compwork->pre_compress);
-  status_printf (so, "post-compress bytes," counter_format, lzo_compwork->post_compress);
-  status_printf (so, "pre-decompress bytes," counter_format, lzo_compwork->pre_decompress);
-  status_printf (so, "post-decompress bytes," counter_format, lzo_compwork->post_decompress);
-#endif
-}
+const struct compress_alg lzo_alg = {
+  "lzo",
+  lzo_compress_init,
+  lzo_compress_uninit,
+  lzo_compress,
+  lzo_decompress
+};
 
 #else
 static void dummy(void) {}