Adding upstream version 4.99.4.upstream/4.99.4

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 200 insertions, 0 deletions

diff --git a/in_cksum.c b/in_cksum.c
new file mode 100644
index 0000000..eb7c634
--- /dev/null
+++ b/in_cksum.c
@@ -0,0 +1,200 @@
+/* in_cksum.c
+ * 4.4-Lite-2 Internet checksum routine, modified to take a vector of
+ * pointers/lengths giving the pieces to be checksummed.  Also using
+ * Tahoe/CGI version of ADDCARRY(x) macro instead of from portable version.
+ */
+
+/*
+ * Copyright (c) 1988, 1992, 1993
+ *	The Regents of the University of California.  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, 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.
+ * 3. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
+ *
+ *	@(#)in_cksum.c	8.1 (Berkeley) 6/10/93
+ */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include "netdissect-stdinc.h"
+
+#include "netdissect.h"
+
+/*
+ * Checksum routine for Internet Protocol family headers (Portable Version).
+ *
+ * This routine is very heavily used in the network
+ * code and should be modified for each CPU to be as fast as possible.
+ */
+
+#define ADDCARRY(x)  {if ((x) > 65535) (x) -= 65535;}
+#define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);}
+
+uint16_t
+in_cksum(const struct cksum_vec *vec, int veclen)
+{
+	const uint16_t *w;
+	int sum = 0;
+	int mlen = 0;
+	int byte_swapped = 0;
+
+	union {
+		uint8_t		c[2];
+		uint16_t	s;
+	} s_util;
+	union {
+		uint16_t	s[2];
+		uint32_t	l;
+	} l_util;
+
+	for (; veclen != 0; vec++, veclen--) {
+		if (vec->len == 0)
+			continue;
+		w = (const uint16_t *)(const void *)vec->ptr;
+		if (mlen == -1) {
+			/*
+			 * The first byte of this chunk is the continuation
+			 * of a word spanning between this chunk and the
+			 * last chunk.
+			 *
+			 * s_util.c[0] is already saved when scanning previous
+			 * chunk.
+			 */
+			s_util.c[1] = *(const uint8_t *)w;
+			sum += s_util.s;
+			w = (const uint16_t *)(const void *)((const uint8_t *)w + 1);
+			mlen = vec->len - 1;
+		} else
+			mlen = vec->len;
+		/*
+		 * Force to even boundary.
+		 */
+		if ((1 & (uintptr_t) w) && (mlen > 0)) {
+			REDUCE;
+			sum <<= 8;
+			s_util.c[0] = *(const uint8_t *)w;
+			w = (const uint16_t *)(const void *)((const uint8_t *)w + 1);
+			mlen--;
+			byte_swapped = 1;
+		}
+		/*
+		 * Unroll the loop to make overhead from
+		 * branches &c small.
+		 */
+		while ((mlen -= 32) >= 0) {
+			sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
+			sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
+			sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
+			sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
+			w += 16;
+		}
+		mlen += 32;
+		while ((mlen -= 8) >= 0) {
+			sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
+			w += 4;
+		}
+		mlen += 8;
+		if (mlen == 0 && byte_swapped == 0)
+			continue;
+		REDUCE;
+		while ((mlen -= 2) >= 0) {
+			sum += *w++;
+		}
+		if (byte_swapped) {
+			REDUCE;
+			sum <<= 8;
+			byte_swapped = 0;
+			if (mlen == -1) {
+				s_util.c[1] = *(const uint8_t *)w;
+				sum += s_util.s;
+				mlen = 0;
+			} else
+				mlen = -1;
+		} else if (mlen == -1)
+			s_util.c[0] = *(const uint8_t *)w;
+	}
+	if (mlen == -1) {
+		/* The last mbuf has odd # of bytes. Follow the
+		   standard (the odd byte may be shifted left by 8 bits
+		   or not as determined by endian-ness of the machine) */
+		s_util.c[1] = 0;
+		sum += s_util.s;
+	}
+	REDUCE;
+	return (~sum & 0xffff);
+}
+
+/*
+ * Given the host-byte-order value of the checksum field in a packet
+ * header, and the network-byte-order computed checksum of the data
+ * that the checksum covers (including the checksum itself), compute
+ * what the checksum field *should* have been.
+ */
+uint16_t
+in_cksum_shouldbe(uint16_t sum, uint16_t computed_sum)
+{
+	uint32_t shouldbe;
+
+	/*
+	 * The value that should have gone into the checksum field
+	 * is the negative of the value gotten by summing up everything
+	 * *but* the checksum field.
+	 *
+	 * We can compute that by subtracting the value of the checksum
+	 * field from the sum of all the data in the packet, and then
+	 * computing the negative of that value.
+	 *
+	 * "sum" is the value of the checksum field, and "computed_sum"
+	 * is the negative of the sum of all the data in the packets,
+	 * so that's -(-computed_sum - sum), or (sum + computed_sum).
+	 *
+	 * All the arithmetic in question is one's complement, so the
+	 * addition must include an end-around carry; we do this by
+	 * doing the arithmetic in 32 bits (with no sign-extension),
+	 * and then adding the upper 16 bits of the sum, which contain
+	 * the carry, to the lower 16 bits of the sum, and then do it
+	 * again in case *that* sum produced a carry.
+	 *
+	 * As RFC 1071 notes, the checksum can be computed without
+	 * byte-swapping the 16-bit words; summing 16-bit words
+	 * on a big-endian machine gives a big-endian checksum, which
+	 * can be directly stuffed into the big-endian checksum fields
+	 * in protocol headers, and summing words on a little-endian
+	 * machine gives a little-endian checksum, which must be
+	 * byte-swapped before being stuffed into a big-endian checksum
+	 * field.
+	 *
+	 * "computed_sum" is a network-byte-order value, so we must put
+	 * it in host byte order before subtracting it from the
+	 * host-byte-order value from the header; the adjusted checksum
+	 * will be in host byte order, which is what we'll return.
+	 */
+	shouldbe = sum;
+	shouldbe += ntohs(computed_sum);
+	shouldbe = (shouldbe & 0xFFFF) + (shouldbe >> 16);
+	shouldbe = (shouldbe & 0xFFFF) + (shouldbe >> 16);
+	return (uint16_t)shouldbe;
+}