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siphash: Make siphash functions consistently return 64-bit results

Some of the siphas_*b() functions return 64-bit results, others 32-bit
results, with no obvious pattern.  siphash_32b() also appears to do this
incorrectly - taking the 64-bit hash value and simply returning it
truncated, rather than folding the two halves together.

Since SipHash proper is defined to give a 64-bit hash, make all of them
return 64-bit results.  In the one caller which needs a 32-bit value,
tcp_seq_init() do the fold down to 32-bits ourselves.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This commit is contained in:
David Gibson 2023-09-28 11:20:53 +10:00 committed by Stefano Brivio
parent c1d2a070f2
commit ca6e94702c
3 changed files with 14 additions and 16 deletions

7
tcp.c
View file

@ -1826,7 +1826,8 @@ static void tcp_seq_init(const struct ctx *c, struct tcp_tap_conn *conn,
.srcport = conn->fport,
.dstport = conn->eport,
};
uint32_t ns, seq = 0;
uint64_t hash;
uint32_t ns;
if (CONN_V4(conn))
inany_from_af(&aany, AF_INET, &c->ip4.addr);
@ -1834,12 +1835,12 @@ static void tcp_seq_init(const struct ctx *c, struct tcp_tap_conn *conn,
inany_from_af(&aany, AF_INET6, &c->ip6.addr);
in.dst = aany;
seq = siphash_36b((uint8_t *)&in, c->tcp.hash_secret);
hash = siphash_36b((uint8_t *)&in, c->tcp.hash_secret);
/* 32ns ticks, overflows 32 bits every 137s */
ns = (now->tv_sec * 1000000000 + now->tv_nsec) >> 5;
conn->seq_to_tap = seq + ns;
conn->seq_to_tap = ((uint32_t)(hash >> 32) ^ (uint32_t)hash) + ns;
}
/**