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Merge pull request #1509 from zerotier/dev-antiflap

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Proposed fix for "path amnesia"
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Adam Ierymenko 2021-12-13 15:17:40 -05:00 committed by GitHub
commit f0e824416b
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2 changed files with 51 additions and 11 deletions
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2
include/ZeroTierOne.h
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@ -163,7 +163,7 @@ extern "C" {
/**
* Maximum number of direct network paths to a given peer
*/
#define ZT_MAX_PEER_NETWORK_PATHS 16
#define ZT_MAX_PEER_NETWORK_PATHS 64
/**
* Maximum number of path configurations that can be set

60
node/Peer.cpp
View File

@ -118,28 +118,68 @@ void Peer::received(
}
if ( (!havePath) && RR->node->shouldUsePathForZeroTierTraffic(tPtr,_id.address(),path->localSocket(),path->address()) ) {
/**
* First, fill all free slots before attempting to replace a path
* - If the above fails, attempt to replace the path that has been dead the longest
* - If there are no free slots, and no dead paths (unlikely), then replace old path most similar to new path
* - If all of the above fails to yield a suitable replacement. Replace first path found to have lower `(quality / priority)`
*/
if (verb == Packet::VERB_OK) {
Mutex::Lock _l(_paths_m);
unsigned int replacePath = ZT_MAX_PEER_NETWORK_PATHS;
uint64_t maxScore = 0;
uint64_t currScore;
long replacePathQuality = 0;
bool foundFreeSlot = false;
for(unsigned int i=0;i<ZT_MAX_PEER_NETWORK_PATHS;++i) {
currScore = 0;
if (_paths[i].p) {
if ( (!_paths[i].p->alive(now)) || _paths[i].p->address().ipsEqual(path->address()) ) {
replacePath = i;
break;
} else {
const long q = _paths[i].p->quality(now) / _paths[i].priority;
if (q > replacePathQuality) {
replacePathQuality = q;
replacePath = i;
// Reward dead paths
if (!_paths[i].p->alive(now)) {
currScore = _paths[i].p->age(now) / 1000;
}
// Reward as similarity increases
if (_paths[i].p->address().ipsEqual(path->address())) {
currScore++;
if (_paths[i].p->address().port() == path->address().port()) {
currScore++;
if (_paths[i].p->localSocket() == path->localSocket()) {
currScore++; // max score (3)
}
}
}
} else {
// If best so far, mark for replacement
if (currScore > maxScore) {
maxScore = currScore;
replacePath = i;
}
}
else {
foundFreeSlot = true;
replacePath = i;
break;
}
}
if (!foundFreeSlot) {
if (maxScore > 3) {
// Do nothing. We found a dead path and have already marked it as a candidate
}
// If we couldn't find a replacement by matching, replacing a dead path, or taking a free slot, then replace by quality
else if (maxScore == 0) {
for(unsigned int i=0;i<ZT_MAX_PEER_NETWORK_PATHS;++i) {
if (_paths[i].p) {
const long q = _paths[i].p->quality(now) / _paths[i].priority;
if (q > replacePathQuality) {
replacePathQuality = q;
replacePath = i;
}
}
}
}
}
if (replacePath != ZT_MAX_PEER_NETWORK_PATHS) {
RR->t->peerLearnedNewPath(tPtr, networkId, *this, path, packetId);