core: add more transports (#574)

* core: add listening for other protocols

Allow CoreDNS to listen for TLS request coming over port 853. This can
be enabled with `tls://` in the config file.

Implement listening for grps:// as well.

a Corefile like:

~~~
. tls://.:1853 {
    whoami
    tls
}
~~~

Means we listen on 1853 for tls requests, the `tls` config item allows
configuration for TLS parameters. We *might* be tempted to use Caddy's
Let's Encrypt implementation here.

* Refactor coredns/grpc into CoreDNS

This makes gRPC a first class citizen in CoreDNS. Add defines as being
just another server.

* some cleanups

* unexport the servers

* Move protobuf dir

* Hook up TLS properly

* Fix test

* listen for TLS as well. README updates

* disable test, fix package

* fix test

* Fix tests

* Fix remaining test

* Some tests

* Make the test work

* Add grpc test from #580

* fix crash

* Fix tests

* Close conn

* README cleanups

* README

* link RFC

11 files changed, 126 insertions, 166 deletions

diff --git a/middleware/erratic/erratic.go b/middleware/erratic/erratic.go
index 3aec36798..a3fbb2e8e 100644
--- a/middleware/erratic/erratic.go
+++ b/middleware/erratic/erratic.go
@@ -38,7 +38,7 @@ func (e *Erratic) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg
 	m.Authoritative = true
 
 	// small dance to copy rrA or rrAAAA into a non-pointer var that allows us to overwrite the ownername
-	// in a non-racy manor.
+	// in a non-racy way.
 	switch state.QType() {
 	case dns.TypeA:
 		rr := *(rrA.(*dns.A))
diff --git a/middleware/normalize.go b/middleware/normalize.go
index 87f3ce703..77ef97993 100644
--- a/middleware/normalize.go
+++ b/middleware/normalize.go
@@ -7,6 +7,8 @@ import (
 	"github.com/miekg/dns"
 )
 
+// See core/dnsserver/address.go - we should unify these two impls.
+
 // Zones respresents a lists of zone names.
 type Zones []string
 
@@ -56,12 +58,24 @@ type (
 )
 
 // Normalize will return the host portion of host, stripping
-// of any port. The host will also be fully qualified and lowercased.
+// of any port or transport. The host will also be fully qualified and lowercased.
 func (h Host) Normalize() string {
+
+	s := string(h)
+
+	switch {
+	case strings.HasPrefix(s, TransportTLS+"://"):
+		s = s[len(TransportTLS+"://"):]
+	case strings.HasPrefix(s, TransportDNS+"://"):
+		s = s[len(TransportDNS+"://"):]
+	case strings.HasPrefix(s, TransportGRPC+"://"):
+		s = s[len(TransportGRPC+"://"):]
+	}
+
 	// separate host and port
-	host, _, err := net.SplitHostPort(string(h))
+	host, _, err := net.SplitHostPort(s)
 	if err != nil {
-		host, _, _ = net.SplitHostPort(string(h) + ":")
+		host, _, _ = net.SplitHostPort(s + ":")
 	}
 	return Name(host).Normalize()
 }
@@ -77,3 +91,10 @@ func (a Addr) Normalize() string {
 	// TODO(miek): lowercase it?
 	return net.JoinHostPort(addr, port)
 }
+
+// Duplicated from core/dnsserver/address.go !
+const (
+	TransportDNS  = "dns"
+	TransportTLS  = "tls"
+	TransportGRPC = "grpc"
+)
diff --git a/middleware/proxy/grpc.go b/middleware/proxy/grpc.go
index c480d3cf2..d3ed14ccd 100644
--- a/middleware/proxy/grpc.go
+++ b/middleware/proxy/grpc.go
@@ -5,16 +5,13 @@ import (
 	"crypto/tls"
 	"log"
 
-	"github.com/grpc-ecosystem/grpc-opentracing/go/otgrpc"
-
-	"github.com/coredns/coredns/middleware/proxy/pb"
 	"github.com/coredns/coredns/middleware/trace"
+	"github.com/coredns/coredns/pb"
 	"github.com/coredns/coredns/request"
 
+	"github.com/grpc-ecosystem/grpc-opentracing/go/otgrpc"
 	"github.com/miekg/dns"
-
 	opentracing "github.com/opentracing/opentracing-go"
-
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/credentials"
 )
diff --git a/middleware/proxy/pb/dns.pb.go b/middleware/proxy/pb/dns.pb.go
deleted file mode 100644
index 3117102ab..000000000
--- a/middleware/proxy/pb/dns.pb.go
+++ /dev/null
@@ -1,140 +0,0 @@
-// Code generated by protoc-gen-go.
-// source: dns.proto
-// DO NOT EDIT!
-
-/*
-Package pb is a generated protocol buffer package.
-
-It is generated from these files:
-	dns.proto
-
-It has these top-level messages:
-	DnsPacket
-*/
-package pb
-
-import proto "github.com/golang/protobuf/proto"
-import fmt "fmt"
-import math "math"
-
-import (
-	context "golang.org/x/net/context"
-	grpc "google.golang.org/grpc"
-)
-
-// Reference imports to suppress errors if they are not otherwise used.
-var _ = proto.Marshal
-var _ = fmt.Errorf
-var _ = math.Inf
-
-// This is a compile-time assertion to ensure that this generated file
-// is compatible with the proto package it is being compiled against.
-// A compilation error at this line likely means your copy of the
-// proto package needs to be updated.
-const _ = proto.ProtoPackageIsVersion2 // please upgrade the proto package
-
-type DnsPacket struct {
-	Msg []byte `protobuf:"bytes,1,opt,name=msg,proto3" json:"msg,omitempty"`
-}
-
-func (m *DnsPacket) Reset()                    { *m = DnsPacket{} }
-func (m *DnsPacket) String() string            { return proto.CompactTextString(m) }
-func (*DnsPacket) ProtoMessage()               {}
-func (*DnsPacket) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{0} }
-
-func (m *DnsPacket) GetMsg() []byte {
-	if m != nil {
-		return m.Msg
-	}
-	return nil
-}
-
-func init() {
-	proto.RegisterType((*DnsPacket)(nil), "coredns.dns.DnsPacket")
-}
-
-// Reference imports to suppress errors if they are not otherwise used.
-var _ context.Context
-var _ grpc.ClientConn
-
-// This is a compile-time assertion to ensure that this generated file
-// is compatible with the grpc package it is being compiled against.
-const _ = grpc.SupportPackageIsVersion4
-
-// Client API for DnsService service
-
-type DnsServiceClient interface {
-	Query(ctx context.Context, in *DnsPacket, opts ...grpc.CallOption) (*DnsPacket, error)
-}
-
-type dnsServiceClient struct {
-	cc *grpc.ClientConn
-}
-
-func NewDnsServiceClient(cc *grpc.ClientConn) DnsServiceClient {
-	return &dnsServiceClient{cc}
-}
-
-func (c *dnsServiceClient) Query(ctx context.Context, in *DnsPacket, opts ...grpc.CallOption) (*DnsPacket, error) {
-	out := new(DnsPacket)
-	err := grpc.Invoke(ctx, "/coredns.dns.DnsService/Query", in, out, c.cc, opts...)
-	if err != nil {
-		return nil, err
-	}
-	return out, nil
-}
-
-// Server API for DnsService service
-
-type DnsServiceServer interface {
-	Query(context.Context, *DnsPacket) (*DnsPacket, error)
-}
-
-func RegisterDnsServiceServer(s *grpc.Server, srv DnsServiceServer) {
-	s.RegisterService(&_DnsService_serviceDesc, srv)
-}
-
-func _DnsService_Query_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
-	in := new(DnsPacket)
-	if err := dec(in); err != nil {
-		return nil, err
-	}
-	if interceptor == nil {
-		return srv.(DnsServiceServer).Query(ctx, in)
-	}
-	info := &grpc.UnaryServerInfo{
-		Server:     srv,
-		FullMethod: "/coredns.dns.DnsService/Query",
-	}
-	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
-		return srv.(DnsServiceServer).Query(ctx, req.(*DnsPacket))
-	}
-	return interceptor(ctx, in, info, handler)
-}
-
-var _DnsService_serviceDesc = grpc.ServiceDesc{
-	ServiceName: "coredns.dns.DnsService",
-	HandlerType: (*DnsServiceServer)(nil),
-	Methods: []grpc.MethodDesc{
-		{
-			MethodName: "Query",
-			Handler:    _DnsService_Query_Handler,
-		},
-	},
-	Streams:  []grpc.StreamDesc{},
-	Metadata: "dns.proto",
-}
-
-func init() { proto.RegisterFile("dns.proto", fileDescriptor0) }
-
-var fileDescriptor0 = []byte{
-	// 120 bytes of a gzipped FileDescriptorProto
-	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x09, 0x6e, 0x88, 0x02, 0xff, 0xe2, 0xe2, 0x4c, 0xc9, 0x2b, 0xd6,
-	0x2b, 0x28, 0xca, 0x2f, 0xc9, 0x17, 0xe2, 0x4e, 0xce, 0x2f, 0x4a, 0x05, 0x71, 0x53, 0xf2, 0x8a,
-	0x95, 0x64, 0xb9, 0x38, 0x5d, 0xf2, 0x8a, 0x03, 0x12, 0x93, 0xb3, 0x53, 0x4b, 0x84, 0x04, 0xb8,
-	0x98, 0x73, 0x8b, 0xd3, 0x25, 0x18, 0x15, 0x18, 0x35, 0x78, 0x82, 0x40, 0x4c, 0x23, 0x57, 0x2e,
-	0x2e, 0x97, 0xbc, 0xe2, 0xe0, 0xd4, 0xa2, 0xb2, 0xcc, 0xe4, 0x54, 0x21, 0x73, 0x2e, 0xd6, 0xc0,
-	0xd2, 0xd4, 0xa2, 0x4a, 0x21, 0x31, 0x3d, 0x24, 0x33, 0xf4, 0xe0, 0x06, 0x48, 0xe1, 0x10, 0x77,
-	0x62, 0x89, 0x62, 0x2a, 0x48, 0x4a, 0x62, 0x03, 0xdb, 0x6f, 0x0c, 0x08, 0x00, 0x00, 0xff, 0xff,
-	0xf5, 0xd1, 0x3f, 0x26, 0x8c, 0x00, 0x00, 0x00,
-}
diff --git a/middleware/proxy/pb/dns.proto b/middleware/proxy/pb/dns.proto
deleted file mode 100644
index 8461f01e6..000000000
--- a/middleware/proxy/pb/dns.proto
+++ /dev/null
@@ -1,12 +0,0 @@
-syntax = "proto3";
-
-package coredns.dns;
-option go_package = "pb";
-
-message DnsPacket {
-	bytes msg = 1;
-}
-
-service DnsService {
-	rpc Query (DnsPacket) returns (DnsPacket);
-}
diff --git a/middleware/reverse/setup.go b/middleware/reverse/setup.go
index ea94aea7d..56ab620fa 100644
--- a/middleware/reverse/setup.go
+++ b/middleware/reverse/setup.go
@@ -40,8 +40,7 @@ func reverseParse(c *caddy.Controller) (nets networks, fall bool, err error) {
 	zones := make([]string, len(c.ServerBlockKeys))
 
 	for i, str := range c.ServerBlockKeys {
-		host, _, _ := net.SplitHostPort(str)
-		zones[i] = strings.ToLower(host)
+		zones[i] = middleware.Host(str).Normalize()
 	}
 
 	for c.Next() {
diff --git a/middleware/root/root.go b/middleware/root/root.go
index 6a26fbd1a..d03ecb8a4 100644
--- a/middleware/root/root.go
+++ b/middleware/root/root.go
@@ -5,6 +5,7 @@ import (
 	"os"
 
 	"github.com/coredns/coredns/core/dnsserver"
+	"github.com/coredns/coredns/middleware"
 
 	"github.com/mholt/caddy"
 )
@@ -21,7 +22,7 @@ func setup(c *caddy.Controller) error {
 
 	for c.Next() {
 		if !c.NextArg() {
-			return c.ArgErr()
+			return middleware.Error("root", c.ArgErr())
 		}
 		config.Root = c.Val()
 	}
@@ -34,7 +35,7 @@ func setup(c *caddy.Controller) error {
 			// But make sure the user knows!
 			log.Printf("[WARNING] Root path does not exist: %s", config.Root)
 		} else {
-			return c.Errf("Unable to access root path '%s': %v", config.Root, err)
+			return middleware.Error("root", c.Errf("unable to access root path '%s': %v", config.Root, err))
 		}
 	}
 
diff --git a/middleware/root/root_test.go b/middleware/root/root_test.go
index 0a58c69bf..6823301f8 100644
--- a/middleware/root/root_test.go
+++ b/middleware/root/root_test.go
@@ -19,7 +19,7 @@ func TestRoot(t *testing.T) {
 
 	// Predefined error substrings
 	parseErrContent := "Parse error:"
-	unableToAccessErrContent := "Unable to access root path"
+	unableToAccessErrContent := "unable to access root path"
 
 	existingDirPath, err := getTempDirPath()
 	if err != nil {
diff --git a/middleware/tls/README.md b/middleware/tls/README.md
new file mode 100644
index 000000000..6070257d3
--- /dev/null
+++ b/middleware/tls/README.md
@@ -0,0 +1,13 @@
+# tls
+
+*tls* extra TLS configuration.
+
+## Syntax
+
+~~~ txt
+tls [STUFF]
+~~~
+
+**STUFF** is things you'll need to configure TLS.
+
+## Examples
diff --git a/middleware/tls/tls.go b/middleware/tls/tls.go
new file mode 100644
index 000000000..2e2586ce5
--- /dev/null
+++ b/middleware/tls/tls.go
@@ -0,0 +1,37 @@
+package tls
+
+import (
+	"github.com/coredns/coredns/core/dnsserver"
+	"github.com/coredns/coredns/middleware"
+	"github.com/coredns/coredns/middleware/pkg/tls"
+
+	"github.com/mholt/caddy"
+)
+
+func init() {
+	caddy.RegisterPlugin("tls", caddy.Plugin{
+		ServerType: "dns",
+		Action:     setup,
+	})
+}
+
+func setup(c *caddy.Controller) error {
+	config := dnsserver.GetConfig(c)
+
+	if config.TLSConfig != nil {
+		return middleware.Error("tls", c.Errf("TLS already configured for this server instance"))
+	}
+
+	for c.Next() {
+		args := c.RemainingArgs()
+		if len(args) != 3 {
+			return middleware.Error("tls", c.ArgErr())
+		}
+		tls, err := tls.NewTLSConfig(args[0], args[1], args[2])
+		if err != nil {
+			return middleware.Error("tls", c.ArgErr())
+		}
+		config.TLSConfig = tls
+	}
+	return nil
+}
diff --git a/middleware/tls/tls_test.go b/middleware/tls/tls_test.go
new file mode 100644
index 000000000..2374d772c
--- /dev/null
+++ b/middleware/tls/tls_test.go
@@ -0,0 +1,44 @@
+package tls
+
+import (
+	"io/ioutil"
+	"log"
+	"strings"
+	"testing"
+
+	"github.com/mholt/caddy"
+)
+
+func TestTLS(t *testing.T) {
+	log.SetOutput(ioutil.Discard)
+
+	tests := []struct {
+		input              string
+		shouldErr          bool
+		expectedRoot       string // expected root, set to the controller. Empty for negative cases.
+		expectedErrContent string // substring from the expected error. Empty for positive cases.
+	}{
+	// positive
+	// negative
+	}
+
+	for i, test := range tests {
+		c := caddy.NewTestController("dns", test.input)
+		err := setup(c)
+		//cfg := dnsserver.GetConfig(c)
+
+		if test.shouldErr && err == nil {
+			t.Errorf("Test %d: Expected error but found %s for input %s", i, err, test.input)
+		}
+
+		if err != nil {
+			if !test.shouldErr {
+				t.Errorf("Test %d: Expected no error but found one for input %s. Error was: %v", i, test.input, err)
+			}
+
+			if !strings.Contains(err.Error(), test.expectedErrContent) {
+				t.Errorf("Test %d: Expected error to contain: %v, found error: %v, input: %s", i, test.expectedErrContent, err, test.input)
+			}
+		}
+	}
+}