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Prevent path-learning loops (#1914)

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* Prevent path-learning loops

* Only allow new overwrite if not bonded
This commit is contained in:
Joseph Henry 2023-03-21 10:18:21 -07:00 committed by GitHub
parent b2a981f353
commit ce9330e9bb
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 41 additions and 50 deletions
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91
node/Peer.cpp
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@ -109,6 +109,13 @@ void Peer::received(
havePath = true;
break;
}
// If same address on same interface then don't learn unless existing path isn't alive (prevents learning loop)
if (_paths[i].p->address().ipsEqual(path->address()) && _paths[i].p->localSocket() == path->localSocket()) {
if (_paths[i].p->alive(now) && !_bond) {
havePath = true;
break;
}
}
} else {
break;
}
@ -116,69 +123,37 @@ 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 oldestPathIdx = ZT_MAX_PEER_NETWORK_PATHS;
unsigned int oldestPathAge = 0;
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) {
// Reward dead paths
if (!_paths[i].p->alive(now)) {
currScore = _paths[i].p->age(now) / 1000;
// Keep track of oldest path as a last resort option
unsigned int currAge = _paths[i].p->age(now);
if (currAge > oldestPathAge) {
oldestPathAge = currAge;
oldestPathIdx = i;
}
// 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)
if (_paths[i].p->localSocket() == path->localSocket()) {
if (!_paths[i].p->alive(now)) {
replacePath = i;
break;
}
}
}
// 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 we didn't find a good candidate then resort to replacing oldest path
replacePath = (replacePath == ZT_MAX_PEER_NETWORK_PATHS) ? oldestPathIdx : replacePath;
if (replacePath != ZT_MAX_PEER_NETWORK_PATHS) {
RR->t->peerLearnedNewPath(tPtr, networkId, *this, path, packetId);
_paths[replacePath].lr = now;
@ -540,11 +515,15 @@ unsigned int Peer::doPingAndKeepalive(void *tPtr,int64_t now)
// let those old links expire.
long maxPriority = 0;
for(unsigned int i=0;i<ZT_MAX_PEER_NETWORK_PATHS;++i) {
if (_paths[i].p)
if (_paths[i].p) {
maxPriority = std::max(_paths[i].priority,maxPriority);
else break;
}
else {
break;
}
}
bool deletionOccurred = false;
for(unsigned int i=0;i<ZT_MAX_PEER_NETWORK_PATHS;++i) {
if (_paths[i].p) {
// Clean expired and reduced priority paths
@ -554,10 +533,22 @@ unsigned int Peer::doPingAndKeepalive(void *tPtr,int64_t now)
_paths[i].p->sent(now);
sent |= (_paths[i].p->address().ss_family == AF_INET) ? 0x1 : 0x2;
}
} else {
_paths[i] = _PeerPath();
}
} else break;
else {
_paths[i] = _PeerPath();
deletionOccurred = true;
}
}
if (!_paths[i].p || deletionOccurred) {
for(unsigned int j=i;j<ZT_MAX_PEER_NETWORK_PATHS;++j) {
if (_paths[j].p && i != j) {
_paths[i] = _paths[j];
_paths[j] = _PeerPath();
break;
}
}
deletionOccurred = false;
}
}
return sent;
}