Add support for dnsseeds with option to filter by servicebits

src/chainparams.cpp

@@ -18,6 +18,14 @@
 
 using namespace std;
 
+std::string CDNSSeedData::getHost(uint64_t requiredServiceBits) const {
+    //use default host for non-filter-capable seeds or if we use the default service bits (NODE_NETWORK)
+    if (!supportsServiceBitsFiltering || requiredServiceBits == NODE_NETWORK)
+        return host;
+    
+    return strprintf("x%x.%s", requiredServiceBits, host);
+}
+
 static CBlock CreateGenesisBlock(const char* pszTimestamp, const CScript& genesisOutputScript, uint32_t nTime, uint32_t nNonce, uint32_t nBits, int32_t nVersion, const CAmount& genesisReward)
 {
     // Genesis block