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tcp: Hash IPv4 and IPv4-mapped-IPv6 addresses the same

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In the tcp_conn structure, we represent the address with an inany_addr
which could be an IPv4 or IPv6 address.  However, we have different paths
which will calculate different hashes for IPv4 and equivalent IPv4-mapped
IPv6 addresses.  This will cause problems for some future changes.

Make the hash function work the same for these two cases, by taking an
inany_addr directly.  Since this represents IPv4 and IPv4-mapped IPv6
addresses the same way, it will trivially hash the same for both cases.

Callers are changed to construct an inany_addr from whatever they have.
Some of that will be elided in later changes.

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 2022-11-17 16:58:56 +11:00 committed by Stefano Brivio
parent ca69c3f196
commit 685f97b8de
2 changed files with 19 additions and 34 deletions
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1
siphash.c
View file

@ -104,6 +104,7 @@
*
* Return: the 64-bit hash output
*/
/* cppcheck-suppress unusedFunction */
uint64_t siphash_8b(const uint8_t *in, const uint64_t *k)
{
PREAMBLE(8);

50
tcp.c
View file

@ -1205,8 +1205,7 @@ static int tcp_hash_match(const struct tcp_tap_conn *conn,
/**
* tcp_hash() - Calculate hash value for connection given address and ports
* @c: Execution context
* @af: Address family, AF_INET or AF_INET6
* @addr: Remote address, pointer to in_addr or in6_addr
* @addr: Remote address
* @tap_port: tap-facing port
* @sock_port: Socket-facing port
*
@ -1215,32 +1214,19 @@ static int tcp_hash_match(const struct tcp_tap_conn *conn,
#if TCP_HASH_NOINLINE
__attribute__((__noinline__)) /* See comment in Makefile */
#endif
static unsigned int tcp_hash(const struct ctx *c, int af, const void *addr,
static unsigned int tcp_hash(const struct ctx *c, const union inany_addr *addr,
in_port_t tap_port, in_port_t sock_port)
{
struct {
union inany_addr addr;
in_port_t tap_port;
in_port_t sock_port;
} __attribute__((__packed__)) in = {
*addr, tap_port, sock_port
};
uint64_t b = 0;
if (af == AF_INET) {
struct {
struct in_addr addr;
in_port_t tap_port;
in_port_t sock_port;
} __attribute__((__packed__)) in = {
*(struct in_addr *)addr, tap_port, sock_port,
};
b = siphash_8b((uint8_t *)&in, c->tcp.hash_secret);
} else if (af == AF_INET6) {
struct {
struct in6_addr addr;
in_port_t tap_port;
in_port_t sock_port;
} __attribute__((__packed__)) in = {
*(struct in6_addr *)addr, tap_port, sock_port,
};
b = siphash_20b((uint8_t *)&in, c->tcp.hash_secret);
}
return (unsigned int)(b % TCP_HASH_TABLE_SIZE);
}
@ -1255,14 +1241,7 @@ static unsigned int tcp_hash(const struct ctx *c, int af, const void *addr,
static unsigned int tcp_conn_hash(const struct ctx *c,
const struct tcp_tap_conn *conn)
{
const struct in_addr *a4 = inany_v4(&conn->addr);
if (a4)
return tcp_hash(c, AF_INET, a4,
conn->tap_port, conn->sock_port);
else
return tcp_hash(c, AF_INET6, &conn->addr.a6,
conn->tap_port, conn->sock_port);
return tcp_hash(c, &conn->addr, conn->tap_port, conn->sock_port);
}
/**
@ -1275,9 +1254,11 @@ static unsigned int tcp_conn_hash(const struct ctx *c,
static void tcp_hash_insert(const struct ctx *c, struct tcp_tap_conn *conn,
int af, const void *addr)
{
union inany_addr aany;
int b;
b = tcp_hash(c, af, addr, conn->tap_port, conn->sock_port);
inany_from_af(&aany, af, addr);
b = tcp_hash(c, &aany, conn->tap_port, conn->sock_port);
conn->next_index = tc_hash[b] ? CONN_IDX(tc_hash[b]) : -1;
tc_hash[b] = conn;
@ -1357,9 +1338,12 @@ static struct tcp_tap_conn *tcp_hash_lookup(const struct ctx *c,
in_port_t tap_port,
in_port_t sock_port)
{
int b = tcp_hash(c, af, addr, tap_port, sock_port);
union inany_addr aany;
struct tcp_tap_conn *conn;
int b;
inany_from_af(&aany, af, addr);
b = tcp_hash(c, &aany, tap_port, sock_port);
for (conn = tc_hash[b]; conn; conn = conn_at_idx(conn->next_index)) {
if (tcp_hash_match(conn, af, addr, tap_port, sock_port))
return conn;