/*
- * Copyright (c) 2008 Nicira Networks.
+ * Copyright (c) 2008, 2009 Nicira Networks.
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
#include <config.h>
#include "csum.h"
-/* Returns the IP checksum of the 'n' bytes in 'data'. */
+/* Returns the IP checksum of the 'n' bytes in 'data'.
+ *
+ * The return value has the same endianness as the data. That is, if 'data'
+ * consists of a packet in network byte order, then the return value is a value
+ * in network byte order, and if 'data' consists of a data structure in host
+ * byte order, then the return value is in host byte order. */
uint16_t
csum(const void *data, size_t n)
{
}
/* Returns the IP checksum corresponding to 'partial', which is a value updated
- * by some combination of csum_add16(), csum_add32(), and csum_continue(). */
+ * by some combination of csum_add16(), csum_add32(), and csum_continue().
+ *
+ * The return value has the same endianness as the checksummed data. That is,
+ * if the data consist of a packet in network byte order, then the return value
+ * is a value in network byte order, and if the data are a data structure in
+ * host byte order, then the return value is in host byte order. */
uint16_t
csum_finish(uint32_t partial)
{
--- /dev/null
+/*
+ * Copyright (c) 2009 Nicira Networks.
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <config.h>
+#include "csum.h"
+#include <inttypes.h>
+#include <netinet/in.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "random.h"
+#include "util.h"
+
+#undef NDEBUG
+#include <assert.h>
+
+struct test_case {
+ char *data;
+ size_t size;
+ uint16_t csum;
+};
+
+#define TEST_CASE(DATA, CSUM) { DATA, (sizeof DATA) - 1, CSUM }
+
+static const struct test_case test_cases[] = {
+ /* RFC 1071 section 3. */
+ TEST_CASE("\x00\x01\xf2\x03\xf4\xf5\xf6\xf7", (uint16_t) ~0xddf2),
+
+ /* http://www.sbprojects.com/projects/tcpip/theory/theory14.htm */
+ TEST_CASE("\x45\x00\x00\x28\x1F\xFD\x40\x00\x80\x06"
+ "\x00\x00\xC0\xA8\x3B\x0A\xC0\xA8\x3B\x32",
+ 0xe345),
+
+ /* http://mathforum.org/library/drmath/view/54379.html */
+ TEST_CASE("\x86\x5e\xac\x60\x71\x2a\x81\xb5", 0xda60),
+};
+
+static void
+mark(char c)
+{
+ putchar(c);
+ fflush(stdout);
+}
+
+#if 0
+/* This code is useful for generating new test cases for RFC 1624 section 4. */
+static void
+generate_rfc1624_test_case(void)
+{
+ int i;
+
+ for (i = 0; i < 10000000; i++) {
+ uint32_t data[8];
+ int j;
+
+ for (j = 0; j < 8; j++) {
+ data[j] = random_uint32();
+ }
+ data[7] &= 0x0000ffff;
+ data[7] |= 0x55550000;
+ if (ntohs(~csum(data, sizeof data - 2)) == 0xcd7a) {
+ ovs_hex_dump(stdout, data, sizeof data, 0, false);
+ exit(0);
+ }
+ }
+}
+#endif
+
+
+
+/* Make sure we get the calculation in RFC 1624 section 4 correct. */
+static void
+test_rfc1624(void)
+{
+ /* "...an IP packet header in which a 16-bit field m = 0x5555..." */
+ uint8_t data[32] =
+ "\xfe\x8f\xc1\x14\x4b\x6f\x70\x2a\x80\x29\x78\xc0\x58\x81\x77\xaa"
+ "\x66\x64\xfc\x96\x63\x97\x64\xee\x12\x53\x1d\xa9\x2d\xa9\x55\x55";
+
+ /* "...the one's complement sum of all other header octets is 0xCD7A." */
+ assert(ntohs(csum(data, sizeof data - 2)) == (uint16_t) ~0xcd7a);
+
+ /* "...the header checksum would be:
+
+ HC = ~(0xCD7A + 0x5555)
+ = ~0x22D0
+ = 0xDD2F"
+ */
+ assert(ntohs(csum(data, sizeof data)) == 0xdd2f);
+
+ /* "a 16-bit field m = 0x5555 changes to m' = 0x3285..." */
+ data[30] = 0x32;
+ data[31] = 0x85;
+
+ /* "The new checksum via recomputation is:
+
+ HC' = ~(0xCD7A + 0x3285)
+ = ~0xFFFF
+ = 0x0000"
+ */
+ assert(ntohs(csum(data, sizeof data)) == 0x0000);
+
+ /* "Applying [Eqn. 3] to the example above, we get the correct result:
+
+ HC' = ~(C + (-m) + m')
+ = ~(0x22D0 + ~0x5555 + 0x3285)
+ = ~0xFFFF
+ = 0x0000" */
+ assert(recalc_csum16(0xdd2f, 0x5555, 0x3285) == 0x0000);
+
+ mark('#');
+}
+
+int
+main(void)
+{
+ const struct test_case *tc;
+ int i;
+
+ for (tc = test_cases; tc < &test_cases[ARRAY_SIZE(test_cases)]; tc++) {
+ const uint16_t *data16 = (const uint16_t *) tc->data;
+ const uint32_t *data32 = (const uint32_t *) tc->data;
+ uint32_t partial;
+ size_t i;
+
+ /* Test csum(). */
+ assert(ntohs(csum(tc->data, tc->size)) == tc->csum);
+ mark('.');
+
+ /* Test csum_add16(). */
+ partial = 0;
+ for (i = 0; i < tc->size / 2; i++) {
+ partial = csum_add16(partial, data16[i]);
+ }
+ assert(ntohs(csum_finish(partial)) == tc->csum);
+ mark('.');
+
+ /* Test csum_add32(). */
+ partial = 0;
+ for (i = 0; i < tc->size / 4; i++) {
+ partial = csum_add32(partial, data32[i]);
+ }
+ assert(ntohs(csum_finish(partial)) == tc->csum);
+ mark('.');
+
+ /* Test alternating csum_add16() and csum_add32(). */
+ partial = 0;
+ for (i = 0; i < tc->size / 4; i++) {
+ if (i % 2) {
+ partial = csum_add32(partial, data32[i]);
+ } else {
+ partial = csum_add16(partial, data16[i * 2]);
+ partial = csum_add16(partial, data16[i * 2 + 1]);
+ }
+ }
+ assert(ntohs(csum_finish(partial)) == tc->csum);
+ mark('.');
+
+ /* Test csum_continue(). */
+ partial = 0;
+ for (i = 0; i < tc->size / 4; i++) {
+ if (i) {
+ partial = csum_continue(partial, &data32[i], 4);
+ } else {
+ partial = csum_continue(partial, &data16[i * 2], 2);
+ partial = csum_continue(partial, &data16[i * 2 + 1], 2);
+ }
+ }
+ assert(ntohs(csum_finish(partial)) == tc->csum);
+ mark('#');
+ }
+
+ test_rfc1624();
+
+ /* Test recalc_csum16(). */
+ for (i = 0; i < 32; i++) {
+ uint16_t old_u16, new_u16;
+ uint16_t old_csum;
+ uint16_t data[16];
+ int j, index;
+
+ for (j = 0; j < ARRAY_SIZE(data); j++) {
+ data[j] = random_uint32();
+ }
+ old_csum = csum(data, sizeof data);
+ index = random_range(ARRAY_SIZE(data));
+ old_u16 = data[index];
+ new_u16 = data[index] = random_uint32();
+ assert(csum(data, sizeof data)
+ == recalc_csum16(old_csum, old_u16, new_u16));
+ mark('.');
+ }
+ mark('#');
+
+ /* Test recalc_csum32(). */
+ for (i = 0; i < 32; i++) {
+ uint32_t old_u32, new_u32;
+ uint16_t old_csum;
+ uint32_t data[16];
+ int j, index;
+
+ for (j = 0; j < ARRAY_SIZE(data); j++) {
+ data[j] = random_uint32();
+ }
+ old_csum = csum(data, sizeof data);
+ index = random_range(ARRAY_SIZE(data));
+ old_u32 = data[index];
+ new_u32 = data[index] = random_uint32();
+ assert(csum(data, sizeof data)
+ == recalc_csum32(old_csum, old_u32, new_u32));
+ mark('.');
+ }
+ mark('#');
+
+ putchar('\n');
+
+ return 0;
+}
projects / openvswitch / commitdiff