add dns support in p2p forward connect

License: MIT
Signed-off-by: Kejie Zhang <601172892@qq.com>

core/commands/p2p.go

@@ -19,6 +19,8 @@ import (
 	ma "gx/ipfs/QmYmsdtJ3HsodkePE3eU3TsCaP2YvPZJ4LoXnNkDE5Tpt7/go-multiaddr"
 	"gx/ipfs/QmZNkThpqfVXs9GNbexPrfBbXSLNYeKrE7jwFM2oqHbyqN/go-libp2p-protocol"
 	pstore "gx/ipfs/QmfAQMFpgDU2U4BXG64qVr8HSiictfWvkSBz7Y2oDj65st/go-libp2p-peerstore"
+	"gx/ipfs/QmfXU2MhWoegxHoeMd3A2ytL2P6CY4FfqGWc23LTNWBwZt/go-multiaddr-dns"
+	"time"
 )
 
 // P2PProtoPrefix is the default required prefix for protocol names
@@ -49,14 +51,16 @@ type P2PStreamsOutput struct {
 	Streams []P2PStreamInfoOutput
 }
 
-var (
+const (
 	allowCustomProtocolOptionName = "allow-custom-protocol"
 	allOptionName                 = "all"
 	protocolOptionName            = "protocol"
 	listenAddressOptionName       = "listen-address"
 	targetAddressOptionName       = "target-address"
 )
 
+var ConnectionTimeout = 10 * time.Second
+
 // P2PCmd is the 'ipfs p2p' command
 var P2PCmd = &cmds.Command{
 	Helptext: cmdkit.HelpText{
@@ -120,7 +124,7 @@ Example:
 			return
 		}
 
-		target, err := ipfsaddr.ParseString(targetOpt)
+		targets, err := parseIpfsAddr(targetOpt)
 		if err != nil {
 			res.SetError(err, cmdkit.ErrNormal)
 			return
@@ -137,14 +141,36 @@ Example:
 			return
 		}
 
-		if err := forwardLocal(n.Context(), n.P2P, n.Peerstore, proto, listen, target); err != nil {
+		if err := forwardLocal(n.Context(), n.P2P, n.Peerstore, proto, listen, targets); err != nil {
 			res.SetError(err, cmdkit.ErrNormal)
 			return
 		}
 		res.SetOutput(nil)
 	},
 }
 
+// parseIpfsAddr is a function that takes in addr string and return a IpfsAddr
+func parseIpfsAddr(addr string) ([]ipfsaddr.IPFSAddr, error) {
+	mutiladdr, err := ma.NewMultiaddr(addr)
+	if err != nil {
+		return nil, err
+	}
+	ctx, cancel := context.WithTimeout(context.Background(), ConnectionTimeout)
+	raddrs, err := madns.Resolve(ctx, mutiladdr)
+	cancel()
+	if len(raddrs) == 0 {
+		return nil, fmt.Errorf("non-resolvable multiaddr about %v", mutiladdr)
+	}
+	iaddrs := make([]ipfsaddr.IPFSAddr, len(raddrs))
+	for i, maddr := range raddrs {
+		iaddrs[i], err = ipfsaddr.ParseMultiaddr(maddr)
+		if err != nil {
+			return nil, fmt.Errorf("invalid peer address: " + err.Error())
+		}
+	}
+	return iaddrs, nil
+}
+
 var p2pListenCmd = &cmds.Command{
 	Helptext: cmdkit.HelpText{
 		Tagline: "Create libp2p service",
@@ -212,13 +238,14 @@ func forwardRemote(ctx context.Context, p *p2p.P2P, proto protocol.ID, target ma
 }
 
 // forwardLocal forwards local connections to a libp2p service
-func forwardLocal(ctx context.Context, p *p2p.P2P, ps pstore.Peerstore, proto protocol.ID, bindAddr ma.Multiaddr, addr ipfsaddr.IPFSAddr) error {
-	if addr != nil {
+func forwardLocal(ctx context.Context, p *p2p.P2P, ps pstore.Peerstore, proto protocol.ID, bindAddr ma.Multiaddr, addrs []ipfsaddr.IPFSAddr) error {
+	for _, addr := range addrs {
 		ps.AddAddr(addr.ID(), addr.Multiaddr(), pstore.TempAddrTTL)
 	}
-
 	// TODO: return some info
-	_, err := p.ForwardLocal(ctx, addr.ID(), proto, bindAddr)
+	// the length of the addrs must large than 0
+	// peerIDs in addr must be the same and choose addr[0] to connect
+	_, err := p.ForwardLocal(ctx, addrs[0].ID(), proto, bindAddr)
 	return err
 }