Make dnsseed's definition of acute need include relevant services.

We normally prefer to connect to peers offering the relevant services.

If we're not connected to enough peers with relevant services, we
 probably don't know about them and could use dnsseed's help.
This commit is contained in:
Gregory Maxwell 2016-10-17 23:11:35 +00:00
parent 9583477288
commit 4630479135

View file

@ -1462,12 +1462,19 @@ static std::string GetDNSHost(const CDNSSeedData& data, ServiceFlags* requiredSe
void CConnman::ThreadDNSAddressSeed()
{
// goal: only query DNS seeds if address need is acute
// Avoiding DNS seeds when we don't need them improves user privacy by
// creating fewer identifying DNS requests, reduces trust by giving seeds
// less influence on the network topology, and reduces traffic to the seeds.
if ((addrman.size() > 0) &&
(!GetBoolArg("-forcednsseed", DEFAULT_FORCEDNSSEED))) {
MilliSleep(11 * 1000);
LOCK(cs_vNodes);
if (vNodes.size() >= 2) {
int nRelevant = 0;
for (auto pnode : vNodes) {
nRelevant += pnode->fSuccessfullyConnected && ((pnode->nServices & nRelevantServices) == nRelevantServices);
}
if (nRelevant >= 2) {
LogPrintf("P2P peers available. Skipped DNS seeding.\n");
return;
}