Add test for Internet checksum.
Add 2 impl. of the Internet Checksum. One new optimized nad
one form RFC 1071. Turns out that the current Quagga in_cksum()
is buggy. On Big Endian routers it miscalculates odd sized buffers.
diff --git a/tests/test-checksum.c b/tests/test-checksum.c
index d218840..bd156ba 100644
--- a/tests/test-checksum.c
+++ b/tests/test-checksum.c
@@ -427,6 +427,65 @@
return 1;
}
+int /* return checksum in low-order 16 bits */
+in_cksum_optimized(void *parg, int nbytes)
+{
+ u_short *ptr = parg;
+ register long sum; /* assumes long == 32 bits */
+ register u_short answer; /* assumes u_short == 16 bits */
+ register int count;
+ /*
+ * Our algorithm is simple, using a 32-bit accumulator (sum),
+ * we add sequential 16-bit words to it, and at the end, fold back
+ * all the carry bits from the top 16 bits into the lower 16 bits.
+ */
+
+ sum = 0;
+ count = nbytes >> 1; /* div by 2 */
+ for(ptr--; count; --count)
+ sum += *++ptr;
+
+ if (nbytes & 1) /* Odd */
+ sum += *(u_char *)(++ptr); /* one byte only */
+
+ /*
+ * Add back carry outs from top 16 bits to low 16 bits.
+ */
+
+ sum = (sum >> 16) + (sum & 0xffff); /* add high-16 to low-16 */
+ sum += (sum >> 16); /* add carry */
+ answer = ~sum; /* ones-complement, then truncate to 16 bits */
+ return(answer);
+}
+
+
+int /* return checksum in low-order 16 bits */
+in_cksum_rfc(void *parg, int count)
+/* from RFC 1071 */
+{
+ u_short *addr = parg;
+ /* Compute Internet Checksum for "count" bytes
+ * beginning at location "addr".
+ */
+ register long sum = 0;
+
+ while (count > 1) {
+ /* This is the inner loop */
+ sum += *addr++;
+ count -= 2;
+ }
+ /* Add left-over byte, if any */
+ if (count > 0) {
+ sum += *(u_char *)addr;
+ }
+
+ /* Fold 32-bit sum to 16 bits */
+ while (sum>>16)
+ sum = (sum & 0xffff) + (sum >> 16);
+ return ~sum;
+}
+
+
int
main(int argc, char **argv)
{
@@ -440,18 +499,27 @@
srandom (time (NULL));
while (1) {
- u_int16_t ospfd, isisd, lib;
-
+ u_int16_t ospfd, isisd, lib, in_csum, in_csum_res, in_csum_rfc;
+ int i,j;
+
exercise += EXERCISESTEP;
exercise %= MAXDATALEN;
- for (int i = 0; i < exercise; i += sizeof (long int)) {
+ for (i = 0; i < exercise; i += sizeof (long int)) {
long int rand = random ();
- for (int j = sizeof (long int); j > 0; j--)
+ for (j = sizeof (long int); j > 0; j--)
buffer[i + (sizeof (long int) - j)] = (rand >> (j * 8)) & 0xff;
}
+ in_csum = in_cksum(buffer, exercise);
+ in_csum_res = in_cksum_optimized(buffer, exercise);
+ in_csum_rfc = in_cksum_rfc(buffer, exercise);
+ if (in_csum_res != in_csum || in_csum != in_csum_rfc)
+ printf ("verify: in_chksum failed in_csum:%x, in_csum_res:%x,"
+ "in_csum_rfc %x, len:%d\n",
+ in_csum, in_csum_res, in_csum_rfc, exercise);
+
ospfd = ospfd_checksum (buffer, exercise + sizeof(u_int16_t), exercise);
if (verify (buffer, exercise + sizeof(u_int16_t)))
printf ("verify: ospfd failed\n");
@@ -477,7 +545,7 @@
if (ospfd_vals.a.c0 == isisd_vals.a.c0
&& ospfd_vals.a.c1 == isisd_vals.a.c1) {
printf ("\n");
- for (int i = 0; reducts[i].name != NULL; i++) {
+ for (i = 0; reducts[i].name != NULL; i++) {
ospfd = reducts[i].f (&ospfd_vals,
exercise + sizeof (u_int16_t),
exercise);
@@ -487,7 +555,7 @@
}
printf ("\n u_char testdata [] = {\n ");
- for (int i = 0; i < exercise; i++) {
+ for (i = 0; i < exercise; i++) {
printf ("0x%02x,%s",
buffer[i],
(i + 1) % 8 ? " " : "\n ");