server: Fix connections to onion nodes.

A DNS lookup was being attempted on onion addresses causing
connections to fail. This has been fixed by introducing type
onionAddr (which implements a net.Addr interface) and passing
it to btcdDial.

Also, the following onion related fixes have been made:

* getaddednodeinfo - updated to handle onion addrs.
* TorLookupIP - fixed err being shadowed.
* newServer - rename tcpAddr to netAddr
* addrStringToNetAddr - skip if host is already an IP addr.
* addrStringToNetAddr - err if tor is disabled
* getaddednodeinfo - check if host is already an IP addr.

connmgr/tor.go

@@ -102,7 +102,7 @@ func TorLookupIP(host, proxy string) ([]net.IP, error) {
 		if int(buf[1]) > len(torStatusErrors) {
 			err = ErrTorInvalidProxyResponse
 		} else {
-			err := torStatusErrors[buf[1]]
+			err = torStatusErrors[buf[1]]
 			if err == nil {
 				err = ErrTorInvalidProxyResponse
 			}

rpcserver.go

@@ -919,18 +919,24 @@ func handleGetAddedNodeInfo(s *rpcServer, cmd interface{}, closeChan <-chan stru
 			host = peer.Addr()
 		}
 
-		// Do a DNS lookup for the address.  If the lookup fails, just
-		// use the host.
 		var ipList []string
-		ips, err := btcdLookup(host)
-		if err == nil {
+		switch {
+		case net.ParseIP(host) != nil, strings.HasSuffix(host, ".onion"):
+			ipList = make([]string, 1)
+			ipList[0] = host
+		default:
+			// Do a DNS lookup for the address.  If the lookup fails, just
+			// use the host.
+			ips, err := btcdLookup(host)
+			if err != nil {
+				ipList = make([]string, 1)
+				ipList[0] = host
+				break
+			}
 			ipList = make([]string, 0, len(ips))
 			for _, ip := range ips {
 				ipList = append(ipList, ip.String())
 			}
-		} else {
-			ipList = make([]string, 1)
-			ipList[0] = host
 		}
 
 		// Add the addresses and connection info to the result.

server.go

@@ -65,6 +65,28 @@ var (
 	userAgentVersion = fmt.Sprintf("%d.%d.%d", appMajor, appMinor, appPatch)
 )
 
+// onionAddr implements the net.Addr interface and represents a tor address.
+type onionAddr struct {
+	addr string
+}
+
+// String returns the onion address.
+//
+// This is part of the net.Addr interface.
+func (oa *onionAddr) String() string {
+	return oa.addr
+}
+
+// Network returns "onion".
+//
+// This is part of the net.Addr interface.
+func (oa *onionAddr) Network() string {
+	return "onion"
+}
+
+// Ensure onionAddr implements the net.Addr interface.
+var _ net.Addr = (*onionAddr)(nil)
+
 // broadcastMsg provides the ability to house a bitcoin message to be broadcast
 // to all connected peers except specified excluded peers.
 type broadcastMsg struct {
@@ -2469,13 +2491,13 @@ func newServer(listenAddrs []string, db database.DB, chainParams *chaincfg.Param
 		permanentPeers = cfg.AddPeers
 	}
 	for _, addr := range permanentPeers {
-		tcpAddr, err := addrStringToNetAddr(addr)
+		netAddr, err := addrStringToNetAddr(addr)
 		if err != nil {
 			return nil, err
 		}
 
 		go s.connManager.Connect(&connmgr.ConnReq{
-			Addr:      tcpAddr,
+			Addr:      netAddr,
 			Permanent: true,
 		})
 	}
@@ -2499,16 +2521,38 @@ func newServer(listenAddrs []string, db database.DB, chainParams *chaincfg.Param
 
 // addrStringToNetAddr takes an address in the form of 'host:port' and returns
 // a net.Addr which maps to the original address with any host names resolved
-// to IP addresses.
+// to IP addresses.  It also handles tor addresses properly by returning a
+// net.Addr that encapsulates the address.
 func addrStringToNetAddr(addr string) (net.Addr, error) {
 	host, strPort, err := net.SplitHostPort(addr)
 	if err != nil {
 		return nil, err
 	}
 
+	port, err := strconv.Atoi(strPort)
+	if err != nil {
+		return nil, err
+	}
+
+	// Skip if host is already an IP address.
+	if ip := net.ParseIP(host); ip != nil {
+		return &net.TCPAddr{
+			IP:   ip,
+			Port: port,
+		}, nil
+	}
+
+	// Tor addresses cannot be resolved to an IP, so just return an onion
+	// address instead.
+	if strings.HasSuffix(host, ".onion") {
+		if cfg.NoOnion {
+			return nil, errors.New("tor has been disabled")
+		}
+
+		return &onionAddr{addr: addr}, nil
+	}
+
 	// Attempt to look up an IP address associated with the parsed host.
-	// The btcdLookup function will transparently handle performing the
-	// lookup over Tor if necessary.
 	ips, err := btcdLookup(host)
 	if err != nil {
 		return nil, err
@@ -2517,11 +2561,6 @@ func addrStringToNetAddr(addr string) (net.Addr, error) {
 		return nil, fmt.Errorf("no addresses found for %s", host)
 	}
 
-	port, err := strconv.Atoi(strPort)
-	if err != nil {
-		return nil, err
-	}
-
 	return &net.TCPAddr{
 		IP:   ips[0],
 		Port: port,