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/pkg/replacer/replacer.go

@@ -0,0 +1,115 @@
+package replacer
+
+import (
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/miekg/coredns/middleware/pkg/dnsrecorder"
+	"github.com/miekg/coredns/request"
+
+	"github.com/miekg/dns"
+)
+
+// Replacer is a type which can replace placeholder
+// substrings in a string with actual values from a
+// dns.Msg and responseRecorder. Always use
+// NewReplacer to get one of these.
+type Replacer interface {
+	Replace(string) string
+	Set(key, value string)
+}
+
+type replacer struct {
+	replacements map[string]string
+	emptyValue   string
+}
+
+// New makes a new replacer based on r and rr.
+// Do not create a new replacer until r and rr have all
+// the needed values, because this function copies those
+// values into the replacer. rr may be nil if it is not
+// available. emptyValue should be the string that is used
+// in place of empty string (can still be empty string).
+func New(r *dns.Msg, rr *dnsrecorder.Recorder, emptyValue string) Replacer {
+	req := request.Request{W: rr, Req: r}
+	rep := replacer{
+		replacements: map[string]string{
+			"{type}":  req.Type(),
+			"{name}":  req.Name(),
+			"{class}": req.Class(),
+			"{proto}": req.Proto(),
+			"{when}": func() string {
+				return time.Now().Format(timeFormat)
+			}(),
+			"{remote}": req.IP(),
+			"{port}":   req.Port(),
+		},
+		emptyValue: emptyValue,
+	}
+	if rr != nil {
+		rcode := dns.RcodeToString[rr.Rcode]
+		if rcode == "" {
+			rcode = strconv.Itoa(rr.Rcode)
+		}
+		rep.replacements["{rcode}"] = rcode
+		rep.replacements["{size}"] = strconv.Itoa(rr.Size)
+		rep.replacements["{duration}"] = time.Since(rr.Start).String()
+	}
+
+	// Header placeholders (case-insensitive)
+	rep.replacements[headerReplacer+"id}"] = strconv.Itoa(int(r.Id))
+	rep.replacements[headerReplacer+"opcode}"] = strconv.Itoa(int(r.Opcode))
+	rep.replacements[headerReplacer+"do}"] = boolToString(req.Do())
+	rep.replacements[headerReplacer+"bufsize}"] = strconv.Itoa(req.Size())
+
+	return rep
+}
+
+// Replace performs a replacement of values on s and returns
+// the string with the replaced values.
+func (r replacer) Replace(s string) string {
+	// Header replacements - these are case-insensitive, so we can't just use strings.Replace()
+	for strings.Contains(s, headerReplacer) {
+		idxStart := strings.Index(s, headerReplacer)
+		endOffset := idxStart + len(headerReplacer)
+		idxEnd := strings.Index(s[endOffset:], "}")
+		if idxEnd > -1 {
+			placeholder := strings.ToLower(s[idxStart : endOffset+idxEnd+1])
+			replacement := r.replacements[placeholder]
+			if replacement == "" {
+				replacement = r.emptyValue
+			}
+			s = s[:idxStart] + replacement + s[endOffset+idxEnd+1:]
+		} else {
+			break
+		}
+	}
+
+	// Regular replacements - these are easier because they're case-sensitive
+	for placeholder, replacement := range r.replacements {
+		if replacement == "" {
+			replacement = r.emptyValue
+		}
+		s = strings.Replace(s, placeholder, replacement, -1)
+	}
+
+	return s
+}
+
+// Set sets key to value in the replacements map.
+func (r replacer) Set(key, value string) {
+	r.replacements["{"+key+"}"] = value
+}
+
+func boolToString(b bool) string {
+	if b {
+		return "true"
+	}
+	return "false"
+}
+
+const (
+	timeFormat     = "02/Jan/2006:15:04:05 -0700"
+	headerReplacer = "{>"
+)

middleware/pkg/replacer/replacer_test.go

@@ -0,0 +1,119 @@
+package replacer
+
+/*
+func TestNewReplacer(t *testing.T) {
+	w := httptest.NewRecorder()
+	recordRequest := NewResponseRecorder(w)
+	reader := strings.NewReader(`{"username": "dennis"}`)
+
+	request, err := http.NewRequest("POST", "http://localhost", reader)
+	if err != nil {
+		t.Fatal("Request Formation Failed\n")
+	}
+	replaceValues := NewReplacer(request, recordRequest, "")
+
+	switch v := replaceValues.(type) {
+	case replacer:
+
+		if v.replacements["{host}"] != "localhost" {
+			t.Error("Expected host to be localhost")
+		}
+		if v.replacements["{method}"] != "POST" {
+			t.Error("Expected request method  to be POST")
+		}
+		if v.replacements["{status}"] != "200" {
+			t.Error("Expected status to be 200")
+		}
+
+	default:
+		t.Fatal("Return Value from New Replacer expected pass type assertion into a replacer type\n")
+	}
+}
+
+func TestReplace(t *testing.T) {
+	w := httptest.NewRecorder()
+	recordRequest := NewResponseRecorder(w)
+	reader := strings.NewReader(`{"username": "dennis"}`)
+
+	request, err := http.NewRequest("POST", "http://localhost", reader)
+	if err != nil {
+		t.Fatal("Request Formation Failed\n")
+	}
+	request.Header.Set("Custom", "foobarbaz")
+	request.Header.Set("ShorterVal", "1")
+	repl := NewReplacer(request, recordRequest, "-")
+
+	if expected, actual := "This host is localhost.", repl.Replace("This host is {host}."); expected != actual {
+		t.Errorf("{host} replacement: expected '%s', got '%s'", expected, actual)
+	}
+	if expected, actual := "This request method is POST.", repl.Replace("This request method is {method}."); expected != actual {
+		t.Errorf("{method} replacement: expected '%s', got '%s'", expected, actual)
+	}
+	if expected, actual := "The response status is 200.", repl.Replace("The response status is {status}."); expected != actual {
+		t.Errorf("{status} replacement: expected '%s', got '%s'", expected, actual)
+	}
+	if expected, actual := "The Custom header is foobarbaz.", repl.Replace("The Custom header is {>Custom}."); expected != actual {
+		t.Errorf("{>Custom} replacement: expected '%s', got '%s'", expected, actual)
+	}
+
+	// Test header case-insensitivity
+	if expected, actual := "The cUsToM header is foobarbaz...", repl.Replace("The cUsToM header is {>cUsToM}..."); expected != actual {
+		t.Errorf("{>cUsToM} replacement: expected '%s', got '%s'", expected, actual)
+	}
+
+	// Test non-existent header/value
+	if expected, actual := "The Non-Existent header is -.", repl.Replace("The Non-Existent header is {>Non-Existent}."); expected != actual {
+		t.Errorf("{>Non-Existent} replacement: expected '%s', got '%s'", expected, actual)
+	}
+
+	// Test bad placeholder
+	if expected, actual := "Bad {host placeholder...", repl.Replace("Bad {host placeholder..."); expected != actual {
+		t.Errorf("bad placeholder: expected '%s', got '%s'", expected, actual)
+	}
+
+	// Test bad header placeholder
+	if expected, actual := "Bad {>Custom placeholder", repl.Replace("Bad {>Custom placeholder"); expected != actual {
+		t.Errorf("bad header placeholder: expected '%s', got '%s'", expected, actual)
+	}
+
+	// Test bad header placeholder with valid one later
+	if expected, actual := "Bad -", repl.Replace("Bad {>Custom placeholder {>ShorterVal}"); expected != actual {
+		t.Errorf("bad header placeholders: expected '%s', got '%s'", expected, actual)
+	}
+
+	// Test shorter header value with multiple placeholders
+	if expected, actual := "Short value 1 then foobarbaz.", repl.Replace("Short value {>ShorterVal} then {>Custom}."); expected != actual {
+		t.Errorf("short value: expected '%s', got '%s'", expected, actual)
+	}
+}
+
+func TestSet(t *testing.T) {
+	w := httptest.NewRecorder()
+	recordRequest := NewResponseRecorder(w)
+	reader := strings.NewReader(`{"username": "dennis"}`)
+
+	request, err := http.NewRequest("POST", "http://localhost", reader)
+	if err != nil {
+		t.Fatalf("Request Formation Failed \n")
+	}
+	repl := NewReplacer(request, recordRequest, "")
+
+	repl.Set("host", "getcaddy.com")
+	repl.Set("method", "GET")
+	repl.Set("status", "201")
+	repl.Set("variable", "value")
+
+	if repl.Replace("This host is {host}") != "This host is getcaddy.com" {
+		t.Error("Expected host replacement failed")
+	}
+	if repl.Replace("This request method is {method}") != "This request method is GET" {
+		t.Error("Expected method replacement failed")
+	}
+	if repl.Replace("The response status is {status}") != "The response status is 201" {
+		t.Error("Expected status replacement failed")
+	}
+	if repl.Replace("The value of variable is {variable}") != "The value of variable is value" {
+		t.Error("Expected variable replacement failed")
+	}
+}
+*/