From: wenxu <[email protected]> In case almost or all available ports are taken, clash resolution can take a very long time, resulting in pmd hang in conntrack.
This can happen when many to-be-natted hosts connect to same destination:port (e.g. a proxy) and all connections pass the same SNAT. Pick a random offset in the acceptable range, then try ever smaller number of adjacent port numbers, until either the limit is reached or a useable port was found. This results in at most 248 attempts (128 + 64 + 32 + 16 + 8, i.e. 4 restarts with new search offset) instead of 64000+. And if thenumber of ip address will limit the max attempts and which will lead the total attempts under 248. Signed-off-by: wenxu <[email protected]> --- lib/conntrack.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 46 insertions(+), 4 deletions(-) diff --git a/lib/conntrack.c b/lib/conntrack.c index a6784ba..1b5d6c2 100644 --- a/lib/conntrack.c +++ b/lib/conntrack.c @@ -2426,7 +2426,11 @@ nat_get_unique_tuple(struct conntrack *ct, const struct conn *conn, uint32_t hash = nat_range_hash(conn, ct->hash_basis, nat_info); bool pat_proto = conn->key.nw_proto == IPPROTO_TCP || conn->key.nw_proto == IPPROTO_UDP; - uint16_t min_port, max_port, curr_port; + uint16_t min_port, max_port, curr_port, orig_port; + unsigned int attempts, max_attempts, min_attempts; + uint16_t range_port; + uint32_t range_addr; + unsigned int i; min_addr = nat_info->min_addr; max_addr = nat_info->max_addr; @@ -2438,9 +2442,25 @@ nat_get_unique_tuple(struct conntrack *ct, const struct conn *conn, * we can stop once we reach it. */ guard_addr = curr_addr; - set_port_range(nat_info, &conn->key, hash, &curr_port, + set_port_range(nat_info, &conn->key, hash, &orig_port, &min_port, &max_port); + range_port = max_port - min_port + 1; + if (conn->key.dl_type == htons(ETH_TYPE_IP)) { + range_addr = ntohl(max_addr.ipv4) - ntohl(min_addr.ipv4) + 1; + } else { + range_addr = nat_ipv6_addrs_delta(&nat_info->min_addr.ipv6, + &nat_info->max_addr.ipv6) + 1; + } + max_attempts = 128 / range_addr; + if (max_attempts < 1) { + max_attempts = 1; + } + min_attempts = 16 / range_addr; + if (min_attempts < 2) { + min_attempts = 2; + } + another_round: store_addr_to_key(&curr_addr, &nat_conn->rev_key, nat_info->nat_action); @@ -2454,17 +2474,39 @@ another_round: goto next_addr; } + curr_port = orig_port; + + attempts = range_port; + if (attempts > max_attempts) { + attempts = max_attempts; + } + +another_port_round: + i = 0; FOR_EACH_PORT_IN_RANGE(curr_port, min_port, max_port) { if (nat_info->nat_action & NAT_ACTION_SRC) { nat_conn->rev_key.dst.port = htons(curr_port); } else { nat_conn->rev_key.src.port = htons(curr_port); } - if (!conn_lookup(ct, &nat_conn->rev_key, time_msec(), NULL, NULL)) { - return true; + if (i++ < attempts) { + if (!conn_lookup(ct, &nat_conn->rev_key, + time_msec(), NULL, NULL)) { + return true; + } + } else { + goto next_attempts; } } +next_attempts: + if (attempts < range_port && attempts >= min_attempts) { + attempts /= 2; + curr_port = min_port + (random_uint32() % range_port); + + goto another_port_round; + } + /* Check if next IP is in range and respin. Otherwise, notify * exhaustion to the caller. */ next_addr: -- 1.8.3.1 _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
