From 0bd5f16380b19a655e45302cc141453d4752bf88 Mon Sep 17 00:00:00 2001
From: Hector Sanjuan <code@hector.link>
Date: Thu, 22 Nov 2018 19:53:48 +0100
Subject: [PATCH] Feat: support hostnames in DialArgs() function

License: MIT
Signed-off-by: Hector Sanjuan <code@hector.link>
---
 convert.go      | 20 +++++++++++++++++++-
 convert_test.go |  4 ++++
 package.json    |  6 ++++++
 3 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/convert.go b/convert.go
index 06fb414..c8fbab1 100644
--- a/convert.go
+++ b/convert.go
@@ -5,6 +5,7 @@ import (
 	"net"
 
 	ma "github.com/multiformats/go-multiaddr"
+	madns "github.com/multiformats/go-multiaddr-dns"
 )
 
 var errIncorrectNetAddr = fmt.Errorf("incorrect network addr conversion")
@@ -93,11 +94,14 @@ func FromIP(ip net.IP) (ma.Multiaddr, error) {
 	return FromIPAndZone(ip, "")
 }
 
-// DialArgs is a convenience function returning arguments for use in net.Dial
+// DialArgs is a convenience function that returns network and address as
+// expected by net.Dial. See https://godoc.org/net#Dial for an overview of
+// possible return values.
 func DialArgs(m ma.Multiaddr) (string, string, error) {
 	var (
 		zone, network, ip, port string
 		err                     error
+		hostname                bool
 	)
 
 	ma.ForEach(m, func(c ma.Component) bool {
@@ -123,6 +127,16 @@ func DialArgs(m ma.Multiaddr) (string, string, error) {
 				network = "ip4"
 				ip = c.Value()
 				return true
+			case madns.Dns4Protocol.Code:
+				network = "ip4"
+				hostname = true
+				ip = c.Value()
+				return true
+			case madns.Dns6Protocol.Code:
+				network = "ip6"
+				hostname = true
+				ip = c.Value()
+				return true
 			}
 		case "ip4":
 			switch c.Protocol().Code {
@@ -151,6 +165,7 @@ func DialArgs(m ma.Multiaddr) (string, string, error) {
 	if err != nil {
 		return "", "", err
 	}
+
 	switch network {
 	case "ip6":
 		if zone != "" {
@@ -165,6 +180,9 @@ func DialArgs(m ma.Multiaddr) (string, string, error) {
 		if zone != "" {
 			ip += "%" + zone
 		}
+		if hostname {
+			return network, ip + ":" + port, nil
+		}
 		return network, "[" + ip + "]" + ":" + port, nil
 	default:
 		return "", "", fmt.Errorf("%s is not a 'thin waist' address", m)
diff --git a/convert_test.go b/convert_test.go
index 105f6b7..33250a0 100644
--- a/convert_test.go
+++ b/convert_test.go
@@ -168,4 +168,8 @@ func TestDialArgs(t *testing.T) {
 	test_error("/ip6zone/foo/ip4/127.0.0.1")                        // IP4 doesn't take zone
 	test("/ip6zone/foo/ip6/::1/ip6zone/bar", "ip6", "::1%foo")      // IP over IP
 	test_error("/ip6zone/foo/ip6zone/bar/ip6/::1")                  // Only one zone per IP6
+	test("/dns4/abc.com/tcp/1234", "tcp4", "abc.com:1234")          // DNS4:port
+	test("/dns4/abc.com", "ip4", "abc.com")                         // Just DNS4
+	test("/dns6/abc.com/udp/1234", "udp6", "abc.com:1234")          // DNS6:port
+	test("/dns6/abc.com", "ip6", "abc.com")                         // Just DNS6
 }
diff --git a/package.json b/package.json
index 9808069..b1dd678 100644
--- a/package.json
+++ b/package.json
@@ -12,6 +12,12 @@
       "hash": "QmRKLtwMw131aK7ugC3G7ybpumMz78YrJe5dzneyindvG1",
       "name": "go-multiaddr",
       "version": "1.3.6"
+    },
+    {
+      "author": "lgierth",
+      "hash": "QmT4zgnKCyZBpRyxzsvZqUjzUkMWLJ2pZCw7uk6M6Kto5m",
+      "name": "go-multiaddr-dns",
+      "version": "0.2.6"
     }
   ],
   "gxVersion": "0.6.0",