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. Github-Pull: #8949 Rebased-From: 46304791353d2bb61004a035869612620c30b4eb
TrezarCoin · Oct 19, 2016 · 91ae0b0 · 91ae0b0
1 parent 33cd553
commit 91ae0b0
Showing 1 changed file with 8 additions and 1 deletion.
diff --git a/src/net.cpp b/src/net.cpp
@@ -1497,12 +1497,19 @@ static std::string GetDNSHost(const CDNSSeedData& data, ServiceFlags* requiredSe
 void 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;
         }