plugin/forward: fix TLS setup (#1714)

* plugin/forward: fix TLS setup

Way smaller PR than #1679. Fixes same thing.

* remove println

* put overwritten test back

* context

* update tests

3 files changed, 76 insertions, 5 deletions

diff --git a/plugin/forward/proxy.go b/plugin/forward/proxy.go
index 8454b296d..c788f98cc 100644
--- a/plugin/forward/proxy.go
+++ b/plugin/forward/proxy.go
@@ -57,8 +57,11 @@ func dnsClient(tlsConfig *tls.Config) *dns.Client {
 	return c
 }
 
-// SetTLSConfig sets the TLS config in the lower p.transport.
-func (p *Proxy) SetTLSConfig(cfg *tls.Config) { p.transport.SetTLSConfig(cfg) }
+// SetTLSConfig sets the TLS config in the lower p.transport and in the healthchecking client.
+func (p *Proxy) SetTLSConfig(cfg *tls.Config) {
+	p.transport.SetTLSConfig(cfg)
+	p.client = dnsClient(cfg)
+}
 
 // SetExpire sets the expire duration in the lower p.transport.
 func (p *Proxy) SetExpire(expire time.Duration) { p.transport.SetExpire(expire) }
diff --git a/plugin/forward/proxy_test.go b/plugin/forward/proxy_test.go
index e33e274c0..a46b3f1ee 100644
--- a/plugin/forward/proxy_test.go
+++ b/plugin/forward/proxy_test.go
@@ -9,6 +9,7 @@ import (
 	"github.com/coredns/coredns/plugin/test"
 	"github.com/coredns/coredns/request"
 
+	"github.com/mholt/caddy"
 	"github.com/miekg/dns"
 )
 
@@ -61,3 +62,59 @@ func TestProxyClose(t *testing.T) {
 		}
 	}
 }
+
+func TestProxy(t *testing.T) {
+	s := dnstest.NewServer(func(w dns.ResponseWriter, r *dns.Msg) {
+		ret := new(dns.Msg)
+		ret.SetReply(r)
+		ret.Answer = append(ret.Answer, test.A("example.org. IN A 127.0.0.1"))
+		w.WriteMsg(ret)
+	})
+	defer s.Close()
+
+	c := caddy.NewTestController("dns", "forward . "+s.Addr)
+	f, err := parseForward(c)
+	if err != nil {
+		t.Errorf("Failed to create forwarder: %s", err)
+	}
+	f.OnStartup()
+	defer f.OnShutdown()
+
+	m := new(dns.Msg)
+	m.SetQuestion("example.org.", dns.TypeA)
+	rec := dnstest.NewRecorder(&test.ResponseWriter{})
+
+	if _, err := f.ServeDNS(context.TODO(), rec, m); err != nil {
+		t.Fatal("Expected to receive reply, but didn't")
+	}
+	if x := rec.Msg.Answer[0].Header().Name; x != "example.org." {
+		t.Errorf("Expected %s, got %s", "example.org.", x)
+	}
+}
+
+func TestProxyTLSFail(t *testing.T) {
+	// This is an udp/tcp test server, so we shouldn't reach it with TLS.
+	s := dnstest.NewServer(func(w dns.ResponseWriter, r *dns.Msg) {
+		ret := new(dns.Msg)
+		ret.SetReply(r)
+		ret.Answer = append(ret.Answer, test.A("example.org. IN A 127.0.0.1"))
+		w.WriteMsg(ret)
+	})
+	defer s.Close()
+
+	c := caddy.NewTestController("dns", "forward . tls://"+s.Addr)
+	f, err := parseForward(c)
+	if err != nil {
+		t.Errorf("Failed to create forwarder: %s", err)
+	}
+	f.OnStartup()
+	defer f.OnShutdown()
+
+	m := new(dns.Msg)
+	m.SetQuestion("example.org.", dns.TypeA)
+	rec := dnstest.NewRecorder(&test.ResponseWriter{})
+
+	if _, err := f.ServeDNS(context.TODO(), rec, m); err == nil {
+		t.Fatal("Expected *not* to receive reply, but got one")
+	}
+}
diff --git a/plugin/forward/setup_test.go b/plugin/forward/setup_test.go
index d787a59d0..fba2359b9 100644
--- a/plugin/forward/setup_test.go
+++ b/plugin/forward/setup_test.go
@@ -77,9 +77,16 @@ func TestSetupTLS(t *testing.T) {
 		expectedErr        string
 	}{
 		// positive
+		{`forward . tls://127.0.0.1 {
+				tls_servername dns
+			}`, false, "dns", ""},
 		{`forward . 127.0.0.1 {
-			tls_servername dns
-		}`, false, "dns", ""},
+				tls_servername dns
+			}`, false, "", ""},
+		{`forward . 127.0.0.1 {
+				tls
+			}`, false, "", ""},
+		{`forward . tls://127.0.0.1`, false, "", ""},
 	}
 
 	for i, test := range tests {
@@ -100,8 +107,12 @@ func TestSetupTLS(t *testing.T) {
 			}
 		}
 
-		if !test.shouldErr && test.expectedServerName != f.tlsConfig.ServerName {
+		if !test.shouldErr && test.expectedServerName != "" && test.expectedServerName != f.tlsConfig.ServerName {
 			t.Errorf("Test %d: expected: %q, actual: %q", i, test.expectedServerName, f.tlsConfig.ServerName)
 		}
+
+		if !test.shouldErr && test.expectedServerName != "" && test.expectedServerName != f.proxies[0].client.TLSConfig.ServerName {
+			t.Errorf("Test %d: expected: %q, actual: %q", i, test.expectedServerName, f.proxies[0].client.TLSConfig.ServerName)
+		}
 	}
 }