aboutsummaryrefslogtreecommitdiff
path: root/sys/net/mppcc.c
diff options
context:
space:
mode:
Diffstat (limited to 'sys/net/mppcc.c')
-rw-r--r--sys/net/mppcc.c298
1 files changed, 298 insertions, 0 deletions
diff --git a/sys/net/mppcc.c b/sys/net/mppcc.c
new file mode 100644
index 000000000000..8e1b93224dd1
--- /dev/null
+++ b/sys/net/mppcc.c
@@ -0,0 +1,298 @@
+/*-
+ * Copyright (c) 2002-2004 Jan Dubiec <jdx@slackware.pl>
+ * Copyright (c) 2007 Alexander Motin <mav@freebsd.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice unmodified, this list of conditions, and the following
+ * disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+/*
+ * MPPC decompression library.
+ * Version 1.0
+ *
+ * Note that Hi/Fn (later acquired by Exar Corporation) held US patents
+ * on some implementation-critical aspects of MPPC compression.
+ * These patents lapsed due to non-payment of fees in 2007 and by 2015
+ * expired altogether.
+ */
+
+#include <sys/param.h>
+#include <sys/systm.h>
+
+#include <net/mppc.h>
+
+#define MPPE_HIST_LEN 8192
+
+#define HASH(x) (((40543*(((((x)[0]<<4)^(x)[1])<<4)^(x)[2]))>>4) & 0x1fff)
+
+struct MPPC_comp_state {
+ uint8_t hist[2*MPPE_HIST_LEN];
+ uint16_t histptr;
+ uint16_t hash[MPPE_HIST_LEN];
+};
+
+/* Inserts 1 to 8 bits into the output buffer. */
+static void __inline
+putbits8(uint8_t *buf, uint32_t val, const uint32_t n, uint32_t *i, uint32_t *l)
+{
+ buf += *i;
+ if (*l >= n) {
+ *l = (*l) - n;
+ val <<= *l;
+ *buf = *buf | (val & 0xff);
+ if (*l == 0) {
+ *l = 8;
+ (*i)++;
+ *(++buf) = 0;
+ }
+ } else {
+ (*i)++;
+ *l = 8 - n + (*l);
+ val <<= *l;
+ *buf = *buf | ((val >> 8) & 0xff);
+ *(++buf) = val & 0xff;
+ }
+}
+
+/* Inserts 9 to 16 bits into the output buffer. */
+static void __inline
+putbits16(uint8_t *buf, uint32_t val, const uint32_t n, uint32_t *i, uint32_t *l)
+{
+ buf += *i;
+ if (*l >= n - 8) {
+ (*i)++;
+ *l = 8 - n + (*l);
+ val <<= *l;
+ *buf = *buf | ((val >> 8) & 0xff);
+ *(++buf) = val & 0xff;
+ if (*l == 0) {
+ *l = 8;
+ (*i)++;
+ *(++buf) = 0;
+ }
+ } else {
+ (*i)++; (*i)++;
+ *l = 16 - n + (*l);
+ val <<= *l;
+ *buf = *buf | ((val >> 16) & 0xff);
+ *(++buf) = (val >> 8) & 0xff;
+ *(++buf) = val & 0xff;
+ }
+}
+
+/* Inserts 17 to 24 bits into the output buffer. */
+static void __inline
+putbits24(uint8_t *buf, uint32_t val, const uint32_t n, uint32_t *i, uint32_t *l)
+{
+ buf += *i;
+ if (*l >= n - 16) {
+ (*i)++; (*i)++;
+ *l = 16 - n + (*l);
+ val <<= *l;
+ *buf = *buf | ((val >> 16) & 0xff);
+ *(++buf) = (val >> 8) & 0xff;
+ *(++buf) = val & 0xff;
+ if (*l == 0) {
+ *l = 8;
+ (*i)++;
+ *(++buf) = 0;
+ }
+ } else {
+ (*i)++; (*i)++; (*i)++;
+ *l = 24 - n + (*l);
+ val <<= *l;
+ *buf = *buf | ((val >> 24) & 0xff);
+ *(++buf) = (val >> 16) & 0xff;
+ *(++buf) = (val >> 8) & 0xff;
+ *(++buf) = val & 0xff;
+ }
+}
+
+size_t MPPC_SizeOfCompressionHistory(void)
+{
+ return (sizeof(struct MPPC_comp_state));
+}
+
+void MPPC_InitCompressionHistory(char *history)
+{
+ struct MPPC_comp_state *state = (struct MPPC_comp_state*)history;
+
+ bzero(history, sizeof(struct MPPC_comp_state));
+ state->histptr = MPPE_HIST_LEN;
+}
+
+int MPPC_Compress(u_char **src, u_char **dst, u_long *srcCnt, u_long *dstCnt, char *history, int flags, int undef)
+{
+ struct MPPC_comp_state *state = (struct MPPC_comp_state*)history;
+ uint32_t olen, off, len, idx, i, l;
+ uint8_t *hist, *sbuf, *p, *q, *r, *s;
+ int rtn = MPPC_OK;
+
+ /*
+ * At this point, to avoid possible buffer overflow caused by packet
+ * expansion during/after compression, we should make sure we have
+ * space for the worst case.
+
+ * Maximum MPPC packet expansion is 12.5%. This is the worst case when
+ * all octets in the input buffer are >= 0x80 and we cannot find any
+ * repeated tokens.
+ */
+ if (*dstCnt < (*srcCnt * 9 / 8 + 2)) {
+ rtn &= ~MPPC_OK;
+ return (rtn);
+ }
+
+ /* We can't compress more then MPPE_HIST_LEN bytes in a call. */
+ if (*srcCnt > MPPE_HIST_LEN) {
+ rtn &= ~MPPC_OK;
+ return (rtn);
+ }
+
+ hist = state->hist + MPPE_HIST_LEN;
+ /* check if there is enough room at the end of the history */
+ if (state->histptr + *srcCnt >= 2*MPPE_HIST_LEN) {
+ rtn |= MPPC_RESTART_HISTORY;
+ state->histptr = MPPE_HIST_LEN;
+ memcpy(state->hist, hist, MPPE_HIST_LEN);
+ }
+ /* Add packet to the history. */
+ sbuf = state->hist + state->histptr;
+ memcpy(sbuf, *src, *srcCnt);
+ state->histptr += *srcCnt;
+
+ /* compress data */
+ r = sbuf + *srcCnt;
+ **dst = olen = i = 0;
+ l = 8;
+ while (i < *srcCnt - 2) {
+ s = q = sbuf + i;
+
+ /* Prognose matching position using hash function. */
+ idx = HASH(s);
+ p = hist + state->hash[idx];
+ state->hash[idx] = (uint16_t) (s - hist);
+ if (p > s) /* It was before MPPC_RESTART_HISTORY. */
+ p -= MPPE_HIST_LEN; /* Try previous history buffer. */
+ off = s - p;
+
+ /* Check our prognosis. */
+ if (off > MPPE_HIST_LEN - 1 || off < 1 || *p++ != *s++ ||
+ *p++ != *s++ || *p++ != *s++) {
+ /* No match found; encode literal byte. */
+ if ((*src)[i] < 0x80) { /* literal byte < 0x80 */
+ putbits8(*dst, (uint32_t) (*src)[i], 8, &olen, &l);
+ } else { /* literal byte >= 0x80 */
+ putbits16(*dst, (uint32_t) (0x100|((*src)[i]&0x7f)), 9,
+ &olen, &l);
+ }
+ ++i;
+ continue;
+ }
+
+ /* Find length of the matching fragment */
+#if defined(__amd64__) || defined(__i386__)
+ /* Optimization for CPUs without strict data aligning requirements */
+ while ((*((uint32_t*)p) == *((uint32_t*)s)) && (s < (r - 3))) {
+ p+=4;
+ s+=4;
+ }
+#endif
+ while((*p++ == *s++) && (s <= r));
+ len = s - q - 1;
+ i += len;
+
+ /* At least 3 character match found; code data. */
+ /* Encode offset. */
+ if (off < 64) { /* 10-bit offset; 0 <= offset < 64 */
+ putbits16(*dst, 0x3c0|off, 10, &olen, &l);
+ } else if (off < 320) { /* 12-bit offset; 64 <= offset < 320 */
+ putbits16(*dst, 0xe00|(off-64), 12, &olen, &l);
+ } else if (off < 8192) { /* 16-bit offset; 320 <= offset < 8192 */
+ putbits16(*dst, 0xc000|(off-320), 16, &olen, &l);
+ } else { /* NOTREACHED */
+ __assert_unreachable();
+ rtn &= ~MPPC_OK;
+ return (rtn);
+ }
+
+ /* Encode length of match. */
+ if (len < 4) { /* length = 3 */
+ putbits8(*dst, 0, 1, &olen, &l);
+ } else if (len < 8) { /* 4 <= length < 8 */
+ putbits8(*dst, 0x08|(len&0x03), 4, &olen, &l);
+ } else if (len < 16) { /* 8 <= length < 16 */
+ putbits8(*dst, 0x30|(len&0x07), 6, &olen, &l);
+ } else if (len < 32) { /* 16 <= length < 32 */
+ putbits8(*dst, 0xe0|(len&0x0f), 8, &olen, &l);
+ } else if (len < 64) { /* 32 <= length < 64 */
+ putbits16(*dst, 0x3c0|(len&0x1f), 10, &olen, &l);
+ } else if (len < 128) { /* 64 <= length < 128 */
+ putbits16(*dst, 0xf80|(len&0x3f), 12, &olen, &l);
+ } else if (len < 256) { /* 128 <= length < 256 */
+ putbits16(*dst, 0x3f00|(len&0x7f), 14, &olen, &l);
+ } else if (len < 512) { /* 256 <= length < 512 */
+ putbits16(*dst, 0xfe00|(len&0xff), 16, &olen, &l);
+ } else if (len < 1024) { /* 512 <= length < 1024 */
+ putbits24(*dst, 0x3fc00|(len&0x1ff), 18, &olen, &l);
+ } else if (len < 2048) { /* 1024 <= length < 2048 */
+ putbits24(*dst, 0xff800|(len&0x3ff), 20, &olen, &l);
+ } else if (len < 4096) { /* 2048 <= length < 4096 */
+ putbits24(*dst, 0x3ff000|(len&0x7ff), 22, &olen, &l);
+ } else if (len < 8192) { /* 4096 <= length < 8192 */
+ putbits24(*dst, 0xffe000|(len&0xfff), 24, &olen, &l);
+ } else { /* NOTREACHED */
+ rtn &= ~MPPC_OK;
+ return (rtn);
+ }
+ }
+
+ /* Add remaining octets to the output. */
+ while(*srcCnt - i > 0) {
+ if ((*src)[i] < 0x80) { /* literal byte < 0x80 */
+ putbits8(*dst, (uint32_t) (*src)[i++], 8, &olen, &l);
+ } else { /* literal byte >= 0x80 */
+ putbits16(*dst, (uint32_t) (0x100|((*src)[i++]&0x7f)), 9, &olen,
+ &l);
+ }
+ }
+
+ /* Reset unused bits of the last output octet. */
+ if ((l != 0) && (l != 8)) {
+ putbits8(*dst, 0, l, &olen, &l);
+ }
+
+ /* If result is bigger then original, set flag and flush history. */
+ if ((*srcCnt < olen) || ((flags & MPPC_SAVE_HISTORY) == 0)) {
+ if (*srcCnt < olen)
+ rtn |= MPPC_EXPANDED;
+ bzero(history, sizeof(struct MPPC_comp_state));
+ state->histptr = MPPE_HIST_LEN;
+ }
+
+ *src += *srcCnt;
+ *srcCnt = 0;
+ *dst += olen;
+ *dstCnt -= olen;
+
+ return (rtn);
+}
generated by cgit v1.2.3 (git 2.25.1) at 2025-10-27 12:16:24 +0000