Cleanup: put middleware helper functions in pkgs (#245)

Move all (almost all) Go files in middleware into their
own packages. This makes for better naming and discoverability.

Lot of changes elsewhere to make this change.

The middleware.State was renamed to request.Request which is better,
but still does not cover all use-cases. It was also moved out middleware
because it is used by `dnsserver` as well.

A pkg/dnsutil packages was added for shared, handy, dns util functions.

All normalize functions are now put in normalize.go

middleware/log/log.go

@@ -7,6 +7,11 @@ import (
 
 	"github.com/miekg/coredns/middleware"
 	"github.com/miekg/coredns/middleware/metrics"
+	"github.com/miekg/coredns/middleware/pkg/dnsrecorder"
+	"github.com/miekg/coredns/middleware/pkg/rcode"
+	"github.com/miekg/coredns/middleware/pkg/replacer"
+	"github.com/miekg/coredns/middleware/pkg/roller"
+	"github.com/miekg/coredns/request"
 
 	"github.com/miekg/dns"
 	"golang.org/x/net/context"
@@ -20,32 +25,30 @@ type Logger struct {
 }
 
 func (l Logger) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
-	state := middleware.State{W: w, Req: r}
+	state := request.Request{W: w, Req: r}
 	for _, rule := range l.Rules {
 		if middleware.Name(rule.NameScope).Matches(state.Name()) {
-			responseRecorder := middleware.NewResponseRecorder(w)
-			rcode, err := l.Next.ServeDNS(ctx, responseRecorder, r)
+			responseRecorder := dnsrecorder.New(w)
+			rc, err := l.Next.ServeDNS(ctx, responseRecorder, r)
 
-			if rcode > 0 {
+			if rc > 0 {
 				// There was an error up the chain, but no response has been written yet.
 				// The error must be handled here so the log entry will record the response size.
 				if l.ErrorFunc != nil {
-					l.ErrorFunc(responseRecorder, r, rcode)
+					l.ErrorFunc(responseRecorder, r, rc)
 				} else {
-					rc := middleware.RcodeToString(rcode)
-
 					answer := new(dns.Msg)
-					answer.SetRcode(r, rcode)
+					answer.SetRcode(r, rc)
 					state.SizeAndDo(answer)
 
-					metrics.Report(state, metrics.Dropped, rc, answer.Len(), time.Now())
+					metrics.Report(state, metrics.Dropped, rcode.ToString(rc), answer.Len(), time.Now())
 					w.WriteMsg(answer)
 				}
-				rcode = 0
+				rc = 0
 			}
-			rep := middleware.NewReplacer(r, responseRecorder, CommonLogEmptyValue)
+			rep := replacer.New(r, responseRecorder, CommonLogEmptyValue)
 			rule.Log.Println(rep.Replace(rule.Format))
-			return rcode, err
+			return rc, err
 
 		}
 	}
@@ -58,7 +61,7 @@ type Rule struct {
 	OutputFile string
 	Format     string
 	Log        *log.Logger
-	Roller     *middleware.LogRoller
+	Roller     *roller.LogRoller
 }
 
 const (

middleware/log/log_test.go

@@ -6,7 +6,7 @@ import (
 	"strings"
 	"testing"
 
-	"github.com/miekg/coredns/middleware"
+	"github.com/miekg/coredns/middleware/pkg/dnsrecorder"
 	"github.com/miekg/coredns/middleware/test"
 
 	"github.com/miekg/dns"
@@ -37,7 +37,7 @@ func TestLoggedStatus(t *testing.T) {
 	r := new(dns.Msg)
 	r.SetQuestion("example.org.", dns.TypeA)
 
-	rec := middleware.NewResponseRecorder(&test.ResponseWriter{})
+	rec := dnsrecorder.New(&test.ResponseWriter{})
 
 	rcode, _ := logger.ServeDNS(ctx, rec, r)
 	if rcode != 0 {

middleware/log/setup.go

@@ -6,7 +6,7 @@ import (
 	"os"
 
 	"github.com/miekg/coredns/core/dnsserver"
-	"github.com/miekg/coredns/middleware"
+	"github.com/miekg/coredns/middleware/pkg/roller"
 
 	"github.com/hashicorp/go-syslog"
 	"github.com/mholt/caddy"
@@ -75,13 +75,13 @@ func logParse(c *caddy.Controller) ([]Rule, error) {
 	for c.Next() {
 		args := c.RemainingArgs()
 
-		var logRoller *middleware.LogRoller
+		var logRoller *roller.LogRoller
 		if c.NextBlock() {
 			if c.Val() == "rotate" {
 				if c.NextArg() {
 					if c.Val() == "{" {
 						var err error
-						logRoller, err = middleware.ParseRoller(c)
+						logRoller, err = roller.Parse(c)
 						if err != nil {
 							return nil, err
 						}

middleware/log/setup_test.go

@@ -3,7 +3,7 @@ package log
 import (
 	"testing"
 
-	"github.com/miekg/coredns/middleware"
+	"github.com/miekg/coredns/middleware/pkg/roller"
 
 	"github.com/mholt/caddy"
 )
@@ -68,7 +68,7 @@ func TestLogParse(t *testing.T) {
 			NameScope:  ".",
 			OutputFile: "access.log",
 			Format:     DefaultLogFormat,
-			Roller: &middleware.LogRoller{
+			Roller: &roller.LogRoller{
 				MaxSize:    2,
 				MaxAge:     10,
 				MaxBackups: 3,