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Diffstat (limited to 'src/openvpn/snappy.c')
| -rw-r--r-- | src/openvpn/snappy.c | 189 |
1 files changed, 189 insertions, 0 deletions
diff --git a/src/openvpn/snappy.c b/src/openvpn/snappy.c new file mode 100644 index 0000000..24440ba --- /dev/null +++ b/src/openvpn/snappy.c @@ -0,0 +1,189 @@ +/* + * 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 + */ + +#ifdef HAVE_CONFIG_H +#include "config.h" +#elif defined(_MSC_VER) +#include "config-msvc.h" +#endif + +#include "syshead.h" + +#if defined(ENABLE_SNAPPY) + +#include "snappy-c.h" + +#include "comp.h" +#include "error.h" +#include "otime.h" + +#include "memdbg.h" + +/* Initial command byte to tell our peer if we compressed */ +#define SNAPPY_COMPRESS_BYTE 0x68 + +static void +snap_compress_init (struct compress_context *compctx) +{ + msg (D_INIT_MEDIUM, "Snappy compression initializing"); + ASSERT(compctx->flags & COMP_F_SWAP); +} + +static void +snap_compress_uninit (struct compress_context *compctx) +{ +} + +static void +snap_compress (struct buffer *buf, struct buffer work, + struct compress_context *compctx, + const struct frame* frame) +{ + snappy_status status; + bool compressed = false; + + if (buf->len <= 0) + return; + + /* + * In order to attempt compression, length must be at least COMPRESS_THRESHOLD. + */ + if (buf->len >= COMPRESS_THRESHOLD) + { + const size_t ps = PAYLOAD_SIZE (frame); + size_t zlen = ps + COMP_EXTRA_BUFFER (ps); + + ASSERT (buf_init (&work, FRAME_HEADROOM (frame))); + ASSERT (buf_safe (&work, zlen)); + + if (buf->len > ps) + { + dmsg (D_COMP_ERRORS, "Snappy compression buffer overflow"); + buf->len = 0; + return; + } + + status = snappy_compress((const char *)BPTR(buf), (size_t)BLEN(buf), (char *)BPTR(&work), &zlen); + if (status != SNAPPY_OK) + { + dmsg (D_COMP_ERRORS, "Snappy compression error: %d", status); + buf->len = 0; + return; + } + + ASSERT (buf_safe (&work, zlen)); + work.len = zlen; + compressed = true; + + dmsg (D_COMP, "Snappy compress %d -> %d", buf->len, work.len); + compctx->pre_compress += buf->len; + compctx->post_compress += work.len; + } + + /* did compression save us anything? */ + { + uint8_t comp_head_byte = NO_COMPRESS_BYTE_SWAP; + if (compressed && work.len < buf->len) + { + *buf = work; + comp_head_byte = SNAPPY_COMPRESS_BYTE; + } + + { + uint8_t *head = BPTR (buf); + uint8_t *tail = BEND (buf); + ASSERT (buf_safe (buf, 1)); + ++buf->len; + + /* move head byte of payload to tail */ + *tail = *head; + *head = comp_head_byte; + } + } +} + +static void +snap_decompress (struct buffer *buf, struct buffer work, + struct compress_context *compctx, + const struct frame* frame) +{ + size_t zlen = EXPANDED_SIZE (frame); + snappy_status status; + uint8_t c; /* flag indicating whether or not our peer compressed */ + + if (buf->len <= 0) + return; + + ASSERT (buf_init (&work, FRAME_HEADROOM (frame))); + + /* do unframing/swap (assumes buf->len > 0) */ + { + uint8_t *head = BPTR (buf); + c = *head; + --buf->len; + *head = *BEND (buf); + } + + if (c == SNAPPY_COMPRESS_BYTE) /* packet was compressed */ + { + ASSERT (buf_safe (&work, zlen)); + status = snappy_uncompress((const char *)BPTR(buf), (size_t)BLEN(buf), (char *)BPTR(&work), &zlen); + if (status != SNAPPY_OK) + { + dmsg (D_COMP_ERRORS, "Snappy decompression error: %d", status); + buf->len = 0; + return; + } + + ASSERT (buf_safe (&work, zlen)); + work.len = zlen; + + dmsg (D_COMP, "Snappy decompress %d -> %d", buf->len, work.len); + compctx->pre_decompress += buf->len; + compctx->post_decompress += work.len; + + *buf = work; + } + else if (c == NO_COMPRESS_BYTE_SWAP) /* packet was not compressed */ + { + ; + } + else + { + dmsg (D_COMP_ERRORS, "Bad Snappy decompression header byte: %d", c); + buf->len = 0; + } +} + +const struct compress_alg snappy_alg = { + "snappy", + snap_compress_init, + snap_compress_uninit, + snap_compress, + snap_decompress +}; + +#else +static void dummy(void) {} +#endif /* ENABLE_SNAPPY */ |