From 4cde13c2e5c8ba6b5f42d1dfb1fa98c8bb3c9bcd Mon Sep 17 00:00:00 2001
From: vearne <asdwoshiaotian@gmail.com>
Date: Fri, 6 Nov 2020 11:23:34 +0800
Subject: [PATCH 1/3] add new resolver

---
 primitive/nsresolver.go | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/primitive/nsresolver.go b/primitive/nsresolver.go
index d844373a..a0ab830e 100644
--- a/primitive/nsresolver.go
+++ b/primitive/nsresolver.go
@@ -19,6 +19,7 @@ package primitive
 import (
 	"fmt"
 	"io/ioutil"
+	"net"
 	"net/http"
 	"os"
 	"os/user"
@@ -82,6 +83,44 @@ func (p *passthroughResolver) Description() string {
 	return fmt.Sprintf("passthrough resolver of %v", p.addr)
 }
 
+type dnsResolver struct {
+	addrs    []string
+	failback NsResolver
+}
+
+func NewDNSResolver(addrs []string) *dnsResolver {
+	return &dnsResolver{
+		addrs:    addrs,
+		failback: NewEnvResolver(),
+	}
+}
+
+func (p *dnsResolver) Resolve() []string {
+	finalAddrs := make([]string, 0, len(p.addrs))
+	for _, addr := range p.addrs {
+		// example.com:9876
+		domainPort := strings.Split(addr, ":")
+		if len(domainPort) != 2 {
+			continue
+		}
+		ns, err := net.LookupHost(domainPort[0])
+		if err != nil {
+			continue
+		}
+		for _, host := range ns {
+			finalAddrs = append(finalAddrs, host+":"+domainPort[1])
+		}
+	}
+	if len(finalAddrs) > 0 {
+		return finalAddrs
+	}
+	return p.failback.Resolve()
+}
+
+func (p *dnsResolver) Description() string {
+	return fmt.Sprintf("dns resolver of %v", p.addrs)
+}
+
 const (
 	DEFAULT_NAMESRV_ADDR = "http://jmenv.tbsite.net:8080/rocketmq/nsaddr"
 )

From 97c2717de9b713ea5d663706f0ca076014e6960e Mon Sep 17 00:00:00 2001
From: vearne <asdwoshiaotian@gmail.com>
Date: Fri, 6 Nov 2020 11:42:36 +0800
Subject: [PATCH 2/3] add unit test

---
 primitive/nsresolver_test.go | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/primitive/nsresolver_test.go b/primitive/nsresolver_test.go
index 98d839af..52e4e09c 100644
--- a/primitive/nsresolver_test.go
+++ b/primitive/nsresolver_test.go
@@ -131,3 +131,21 @@ func TesHttpReslverWithSnapshotFileOnce(t *testing.T) {
 		So(Diff(addrs1, srvs), ShouldBeFalse)
 	})
 }
+
+func TestDNSResolver(t *testing.T) {
+	Convey("Test UpdateNameServerAddress Use DNS", t, func() {
+		srvs := []string{
+			"examples.com:9876",
+		}
+
+		hosts, _ := net.LookupHost("examples.com")
+		expectedHosts := make([]string, 0)
+		for _, host:=range hosts{
+			expectedHosts = append(expectedHosts, host + ":9876")
+		}
+		resolver := NewDNSResolver(srvs)
+		addrs := resolver.Resolve()
+
+		So(Diff(expectedHosts, addrs), ShouldBeFalse)
+	})
+}
\ No newline at end of file

From 8208f5958d56123d3f46a0c75351fde618b03502 Mon Sep 17 00:00:00 2001
From: vearne <asdwoshiaotian@gmail.com>
Date: Fri, 27 Nov 2020 10:14:53 +0800
Subject: [PATCH 3/3] update primitive/nsresolver_test.go

---
 primitive/nsresolver_test.go | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/primitive/nsresolver_test.go b/primitive/nsresolver_test.go
index 52e4e09c..68bb955c 100644
--- a/primitive/nsresolver_test.go
+++ b/primitive/nsresolver_test.go
@@ -140,12 +140,12 @@ func TestDNSResolver(t *testing.T) {
 
 		hosts, _ := net.LookupHost("examples.com")
 		expectedHosts := make([]string, 0)
-		for _, host:=range hosts{
-			expectedHosts = append(expectedHosts, host + ":9876")
+		for _, host := range hosts {
+			expectedHosts = append(expectedHosts, host+":9876")
 		}
 		resolver := NewDNSResolver(srvs)
 		addrs := resolver.Resolve()
 
 		So(Diff(expectedHosts, addrs), ShouldBeFalse)
 	})
-}
\ No newline at end of file
+}