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authorJason Reeder <jasonreeder@gmail.com>2017-02-16 04:14:38 -0600
committerLennart Poettering <lennart@poettering.net>2017-02-16 11:14:38 +0100
commit0cbc024d591e1b1095d90494e0337dabd9ef2e19 (patch)
tree57390c3c4240bd0f350a66d85606daf139cc04cc
parent11814bbbae6674a12cfc1d82db4b44653696a674 (diff)
libsystemd-network: ipv4ll probe conflict counter (#5361)
A bug exists where the conflict counter is cleared regardless of whether or not the next probe attempt leads to a successful address acquisition. This causes 'bursts' of MAX_CONFLICTS probes followed by a delay of RATE_LIMIT_INTERVAL instead of a single probe each RATE_LIMIT_INTERVAL when beyond MAX_CONFLICTS. The conflict counter should only be cleared after an address is successfully acquired. This commit achieves that goal. From RFC3927: A host should maintain a counter of the number of address conflicts it has experienced in the process of trying to acquire an address, and if the number of conflicts exceeds MAX_CONFLICTS then the host MUST limit the rate at which it probes for new addresses to no more than one new address per RATE_LIMIT_INTERVAL. This is to prevent catastrophic ARP storms in pathological failure cases, such as a rogue host that answers all ARP probes, causing legitimate hosts to go into an infinite loop attempting to select a usable address. Signed-off-by: Jason Reeder <jasonreeder@gmail.com>
-rw-r--r--src/libsystemd-network/sd-ipv4acd.c2
1 files changed, 0 insertions, 2 deletions
diff --git a/src/libsystemd-network/sd-ipv4acd.c b/src/libsystemd-network/sd-ipv4acd.c
index 4dd343c101..2ebc00f247 100644
--- a/src/libsystemd-network/sd-ipv4acd.c
+++ b/src/libsystemd-network/sd-ipv4acd.c
@@ -242,8 +242,6 @@ static int ipv4acd_on_timeout(sd_event_source *s, uint64_t usec, void *userdata)
r = ipv4acd_set_next_wakeup(acd, RATE_LIMIT_INTERVAL_USEC, PROBE_WAIT_USEC);
if (r < 0)
goto fail;
-
- acd->n_conflict = 0;
} else {
r = ipv4acd_set_next_wakeup(acd, 0, PROBE_WAIT_USEC);
if (r < 0)