Add DNS Bootstrapping

ethereum.go

@@ -262,21 +262,46 @@ func (s *Ethereum) Start() {
 	go s.ReapDeadPeerHandler()
 
 	if ethutil.Config.Seed {
-		ethutil.Config.Log.Debugln("Seeding")
-		// Testnet seed bootstrapping
-		resp, err := http.Get("https://www.ethereum.org/servers.poc3.txt")
-		if err != nil {
-			log.Println("Fetching seed failed:", err)
-			return
-		}
-		defer resp.Body.Close()
-		body, err := ioutil.ReadAll(resp.Body)
-		if err != nil {
-			log.Println("Reading seed failed:", err)
-			return
-		}
+			ethutil.Config.Log.Debugln("Seeding")
+			// DNS Bootstrapping
+			_, nodes,  err := net.LookupSRV("eth", "tcp", "ethereum.org")
+			if(err == nil) {
+				peers := []string{}
+				// Iterate SRV nodes
+				for _, n := range nodes {
+					target := n.Target
+					port := n.Port
+					// Resolve target to ip (Go returns list, so may resolve to multiple ips?)
+					addr, err := net.LookupHost(target)
+					if(err == nil) {
+						for _, a := range addr {
+							// Build string out of SRV port and Resolved IP
+							peer := net.JoinHostPort(a, strconv.Itoa(int(port)))
+							log.Println("Found DNS Bootstrap Peer:", peer)
+							peers = append(peers, peer)
+						}
+					} else {
+						log.Println("Couldn't resolve :", target)
+					}
+				}
+				// Connect to Peer list
+				s.ProcessPeerList(peers)
+			} else {
+				// Fallback to servers.poc3.txt
+				resp, err := http.Get("http://www.ethereum.org/servers.poc3.txt")
+				if err != nil {
+					log.Println("Fetching seed failed:", err)
+					return
+				}
+				defer resp.Body.Close()
+				body, err := ioutil.ReadAll(resp.Body)
+				if err != nil {
+					log.Println("Reading seed failed:", err)
+					return
+				}
 
-		s.ConnectToPeer(string(body))
+				s.ConnectToPeer(string(body))
+			}
 	}
 }