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lib: use iovec for checksum code

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... to allow checksumming noncontiguous blurbs of data.

Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
This commit is contained in:
David Lamparter 2022-02-26 13:20:16 +01:00
parent 264c806da9
commit 89087f23b5
3 changed files with 136 additions and 42 deletions
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85
lib/checksum.c
View File

@ -9,13 +9,24 @@
#include <zebra.h>
#include "checksum.h"
int /* return checksum in low-order 16 bits */
in_cksum(void *parg, int nbytes)
#define add_carry(dst, add) \
do { \
typeof(dst) _add = (add); \
dst += _add; \
if (dst < _add) \
dst++; \
} while (0)
uint16_t in_cksumv(const struct iovec *iov, size_t iov_len)
{
unsigned short *ptr = parg;
register long sum; /* assumes long == 32 bits */
unsigned short oddbyte;
register unsigned short answer; /* assumes unsigned short == 16 bits */
const struct iovec *iov_end;
uint32_t sum = 0;
union {
uint8_t bytes[2];
uint16_t word;
} wordbuf;
bool have_oddbyte = false;
/*
* Our algorithm is simple, using a 32-bit accumulator (sum),
@ -23,17 +34,42 @@ int /* return checksum in low-order 16 bits */
* all the carry bits from the top 16 bits into the lower 16 bits.
*/
sum = 0;
while (nbytes > 1) {
sum += *ptr++;
nbytes -= 2;
for (iov_end = iov + iov_len; iov < iov_end; iov++) {
const uint8_t *ptr, *end;
ptr = (const uint8_t *)iov->iov_base;
end = ptr + iov->iov_len;
if (ptr == end)
continue;
if (have_oddbyte) {
have_oddbyte = false;
wordbuf.bytes[1] = *ptr++;
add_carry(sum, wordbuf.word);
}
while (ptr + 8 <= end) {
add_carry(sum, *(const uint32_t *)(ptr + 0));
add_carry(sum, *(const uint32_t *)(ptr + 4));
ptr += 8;
}
while (ptr + 2 <= end) {
add_carry(sum, *(const uint16_t *)ptr);
ptr += 2;
}
if (ptr + 1 <= end) {
wordbuf.bytes[0] = *ptr++;
have_oddbyte = true;
}
}
/* mop up an odd byte, if necessary */
if (nbytes == 1) {
oddbyte = 0; /* make sure top half is zero */
*((uint8_t *)&oddbyte) = *(uint8_t *)ptr; /* one byte only */
sum += oddbyte;
if (have_oddbyte) {
wordbuf.bytes[1] = 0;
add_carry(sum, wordbuf.word);
}
/*
@ -42,26 +78,7 @@ int /* return checksum in low-order 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 in_cksum_with_ph4(struct ipv4_ph *ph, void *data, int nbytes)
{
uint8_t dat[sizeof(struct ipv4_ph) + nbytes];
memcpy(dat, ph, sizeof(struct ipv4_ph));
memcpy(dat + sizeof(struct ipv4_ph), data, nbytes);
return in_cksum(dat, sizeof(dat));
}
int in_cksum_with_ph6(struct ipv6_ph *ph, void *data, int nbytes)
{
uint8_t dat[sizeof(struct ipv6_ph) + nbytes];
memcpy(dat, ph, sizeof(struct ipv6_ph));
memcpy(dat + sizeof(struct ipv6_ph), data, nbytes);
return in_cksum(dat, sizeof(dat));
return ~sum;
}
/* Fletcher Checksum -- Refer to RFC1008. */

38
lib/checksum.h
View File

@ -27,9 +27,41 @@ struct ipv6_ph {
uint8_t next_hdr;
} __attribute__((packed));
extern int in_cksum(void *data, int nbytes);
extern int in_cksum_with_ph4(struct ipv4_ph *ph, void *data, int nbytes);
extern int in_cksum_with_ph6(struct ipv6_ph *ph, void *data, int nbytes);
extern uint16_t in_cksumv(const struct iovec *iov, size_t iov_len);
static inline uint16_t in_cksum(const void *data, size_t nbytes)
{
struct iovec iov[1];
iov[0].iov_base = (void *)data;
iov[0].iov_len = nbytes;
return in_cksumv(iov, array_size(iov));
}
static inline uint16_t in_cksum_with_ph4(const struct ipv4_ph *ph,
const void *data, size_t nbytes)
{
struct iovec iov[2];
iov[0].iov_base = (void *)ph;
iov[0].iov_len = sizeof(*ph);
iov[1].iov_base = (void *)data;
iov[1].iov_len = nbytes;
return in_cksumv(iov, array_size(iov));
}
static inline uint16_t in_cksum_with_ph6(const struct ipv6_ph *ph,
const void *data, size_t nbytes)
{
struct iovec iov[2];
iov[0].iov_base = (void *)ph;
iov[0].iov_len = sizeof(*ph);
iov[1].iov_base = (void *)data;
iov[1].iov_len = nbytes;
return in_cksumv(iov, array_size(iov));
}
#define FLETCHER_CHECKSUM_VALIDATE 0xffff
extern uint16_t fletcher_checksum(uint8_t *, const size_t len,

55
tests/lib/test_checksum.c
View File

@ -477,6 +477,8 @@ int main(int argc, char **argv)
exercise += EXERCISESTEP;
exercise %= MAXDATALEN;
printf("\rexercising length %d\033[K", exercise);
for (i = 0; i < exercise; i += sizeof(long int)) {
long int rand = frr_weak_random();
@ -489,24 +491,67 @@ int main(int argc, char **argv)
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",
printf("\nverify: 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);
struct iovec iov[3];
uint16_t in_csum_iov;
iov[0].iov_base = buffer;
iov[0].iov_len = exercise / 2;
iov[1].iov_base = buffer + iov[0].iov_len;
iov[1].iov_len = exercise - iov[0].iov_len;
in_csum_iov = in_cksumv(iov, 2);
if (in_csum_iov != in_csum)
printf("\nverify: in_cksumv failed, lens: %zu+%zu\n",
iov[0].iov_len, iov[1].iov_len);
if (exercise >= 6) {
/* force split with byte leftover */
iov[0].iov_base = buffer;
iov[0].iov_len = (exercise / 2) | 1;
iov[1].iov_base = buffer + iov[0].iov_len;
iov[1].iov_len = 2;
iov[2].iov_base = buffer + iov[0].iov_len + 2;
iov[2].iov_len = exercise - iov[0].iov_len - 2;
in_csum_iov = in_cksumv(iov, 3);
if (in_csum_iov != in_csum)
printf("\nverify: in_cksumv failed, lens: %zu+%zu+%zu, got %04x, expected %04x\n",
iov[0].iov_len, iov[1].iov_len,
iov[2].iov_len, in_csum_iov, in_csum);
/* force split without byte leftover */
iov[0].iov_base = buffer;
iov[0].iov_len = (exercise / 2) & ~1UL;
iov[1].iov_base = buffer + iov[0].iov_len;
iov[1].iov_len = 2;
iov[2].iov_base = buffer + iov[0].iov_len + 2;
iov[2].iov_len = exercise - iov[0].iov_len - 2;
in_csum_iov = in_cksumv(iov, 3);
if (in_csum_iov != in_csum)
printf("\nverify: in_cksumv failed, lens: %zu+%zu+%zu, got %04x, expected %04x\n",
iov[0].iov_len, iov[1].iov_len,
iov[2].iov_len, in_csum_iov, in_csum);
}
ospfd = ospfd_checksum(buffer, exercise + sizeof(uint16_t),
exercise);
if (verify(buffer, exercise + sizeof(uint16_t)))
printf("verify: ospfd failed\n");
printf("\nverify: ospfd failed\n");
isisd = iso_csum_create(buffer, exercise + sizeof(uint16_t),
exercise);
if (verify(buffer, exercise + sizeof(uint16_t)))
printf("verify: isisd failed\n");
printf("\nverify: isisd failed\n");
lib = fletcher_checksum(buffer, exercise + sizeof(uint16_t),
exercise);
if (verify(buffer, exercise + sizeof(uint16_t)))
printf("verify: lib failed\n");
printf("\nverify: lib failed\n");
if (ospfd != lib) {
printf("Mismatch in values at size %d\n"
printf("\nMismatch in values at size %d\n"
"ospfd: 0x%04x\tc0: %d\tc1: %d\tx: %d\ty: %d\n"
"isisd: 0x%04x\tc0: %d\tc1: %d\tx: %d\ty: %d\n"
"lib: 0x%04x\n",