diff options
| -rw-r--r-- | tests/test-checksum.c | 80 |
1 files changed, 74 insertions, 6 deletions
diff --git a/tests/test-checksum.c b/tests/test-checksum.c index d218840d..bd156baa 100644 --- a/tests/test-checksum.c +++ b/tests/test-checksum.c @@ -427,6 +427,65 @@ verify (u_char * buffer, testsz_t len) 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 @@ main(int argc, char **argv) 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 @@ main(int argc, char **argv) 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 @@ main(int argc, char **argv) } 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 "); |