Remove the word middleware (#1067)

* Rename middleware to plugin

first pass; mostly used 'sed', few spots where I manually changed
text.

This still builds a coredns binary.

* fmt error

* Rename AddMiddleware to AddPlugin

* Readd AddMiddleware to remain backwards compat

plugin/errors/README.md

@@ -0,0 +1,22 @@
+# errors
+
+*errors* enables error logging.
+
+Any errors encountered during the query processing will be printed to standard output.
+
+## Syntax
+
+~~~
+errors
+~~~
+
+## Examples
+
+Use the *whoami* to respond to queries and Log errors to standard output.
+
+~~~ corefile
+. {
+    whoami
+    errors
+}
+~~~

plugin/errors/errors.go

@@ -0,0 +1,79 @@
+// Package errors implements an HTTP error handling plugin.
+package errors
+
+import (
+	"fmt"
+	"log"
+	"runtime"
+	"strings"
+	"time"
+
+	"github.com/coredns/coredns/plugin"
+	"github.com/coredns/coredns/request"
+
+	"github.com/miekg/dns"
+	"golang.org/x/net/context"
+)
+
+// errorHandler handles DNS errors (and errors from other plugin).
+type errorHandler struct {
+	Next    plugin.Handler
+	LogFile string
+	Log     *log.Logger
+}
+
+// ServeDNS implements the plugin.Handler interface.
+func (h errorHandler) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
+	defer h.recovery(ctx, w, r)
+
+	rcode, err := plugin.NextOrFailure(h.Name(), h.Next, ctx, w, r)
+
+	if err != nil {
+		state := request.Request{W: w, Req: r}
+		errMsg := fmt.Sprintf("%s [ERROR %d %s %s] %v", time.Now().Format(timeFormat), rcode, state.Name(), state.Type(), err)
+
+		h.Log.Println(errMsg)
+	}
+
+	return rcode, err
+}
+
+func (h errorHandler) Name() string { return "errors" }
+
+func (h errorHandler) recovery(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) {
+	rec := recover()
+	if rec == nil {
+		return
+	}
+
+	// Obtain source of panic
+	// From: https://gist.github.com/swdunlop/9629168
+	var name, file string // function name, file name
+	var line int
+	var pc [16]uintptr
+	n := runtime.Callers(3, pc[:])
+	for _, pc := range pc[:n] {
+		fn := runtime.FuncForPC(pc)
+		if fn == nil {
+			continue
+		}
+		file, line = fn.FileLine(pc)
+		name = fn.Name()
+		if !strings.HasPrefix(name, "runtime.") {
+			break
+		}
+	}
+
+	// Trim file path
+	delim := "/coredns/"
+	pkgPathPos := strings.Index(file, delim)
+	if pkgPathPos > -1 && len(file) > pkgPathPos+len(delim) {
+		file = file[pkgPathPos+len(delim):]
+	}
+
+	panicMsg := fmt.Sprintf("%s [PANIC %s %s] %s:%d - %v", time.Now().Format(timeFormat), r.Question[0].Name, dns.Type(r.Question[0].Qtype), file, line, rec)
+	// Currently we don't use the function name, since file:line is more conventional
+	h.Log.Printf(panicMsg)
+}
+
+const timeFormat = "02/Jan/2006:15:04:05 -0700"

plugin/errors/errors_test.go

@@ -0,0 +1,73 @@
+package errors
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"log"
+	"strings"
+	"testing"
+
+	"github.com/coredns/coredns/plugin"
+	"github.com/coredns/coredns/plugin/pkg/dnsrecorder"
+	"github.com/coredns/coredns/plugin/test"
+
+	"github.com/miekg/dns"
+	"golang.org/x/net/context"
+)
+
+func TestErrors(t *testing.T) {
+	buf := bytes.Buffer{}
+	em := errorHandler{Log: log.New(&buf, "", 0)}
+
+	testErr := errors.New("test error")
+	tests := []struct {
+		next         plugin.Handler
+		expectedCode int
+		expectedLog  string
+		expectedErr  error
+	}{
+		{
+			next:         genErrorHandler(dns.RcodeSuccess, nil),
+			expectedCode: dns.RcodeSuccess,
+			expectedLog:  "",
+			expectedErr:  nil,
+		},
+		{
+			next:         genErrorHandler(dns.RcodeNotAuth, testErr),
+			expectedCode: dns.RcodeNotAuth,
+			expectedLog:  fmt.Sprintf("[ERROR %d %s] %v\n", dns.RcodeNotAuth, "example.org. A", testErr),
+			expectedErr:  testErr,
+		},
+	}
+
+	ctx := context.TODO()
+	req := new(dns.Msg)
+	req.SetQuestion("example.org.", dns.TypeA)
+
+	for i, tc := range tests {
+		em.Next = tc.next
+		buf.Reset()
+		rec := dnsrecorder.New(&test.ResponseWriter{})
+		code, err := em.ServeDNS(ctx, rec, req)
+
+		if err != tc.expectedErr {
+			t.Errorf("Test %d: Expected error %v, but got %v",
+				i, tc.expectedErr, err)
+		}
+		if code != tc.expectedCode {
+			t.Errorf("Test %d: Expected status code %d, but got %d",
+				i, tc.expectedCode, code)
+		}
+		if log := buf.String(); !strings.Contains(log, tc.expectedLog) {
+			t.Errorf("Test %d: Expected log %q, but got %q",
+				i, tc.expectedLog, log)
+		}
+	}
+}
+
+func genErrorHandler(rcode int, err error) plugin.Handler {
+	return plugin.HandlerFunc(func(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
+		return rcode, err
+	})
+}

plugin/errors/setup.go

@@ -0,0 +1,55 @@
+package errors
+
+import (
+	"fmt"
+	"log"
+	"os"
+
+	"github.com/coredns/coredns/core/dnsserver"
+	"github.com/coredns/coredns/plugin"
+
+	"github.com/mholt/caddy"
+)
+
+func init() {
+	caddy.RegisterPlugin("errors", caddy.Plugin{
+		ServerType: "dns",
+		Action:     setup,
+	})
+}
+
+func setup(c *caddy.Controller) error {
+	handler, err := errorsParse(c)
+	if err != nil {
+		return plugin.Error("errors", err)
+	}
+
+	handler.Log = log.New(os.Stdout, "", 0)
+
+	dnsserver.GetConfig(c).AddPlugin(func(next plugin.Handler) plugin.Handler {
+		handler.Next = next
+		return handler
+	})
+
+	return nil
+}
+
+func errorsParse(c *caddy.Controller) (errorHandler, error) {
+	handler := errorHandler{}
+
+	for c.Next() {
+		args := c.RemainingArgs()
+		switch len(args) {
+		case 0:
+			handler.LogFile = "stdout"
+		case 1:
+			if args[0] != "stdout" {
+				return handler, fmt.Errorf("invalid log file: %s", args[0])
+			}
+			handler.LogFile = args[0]
+		default:
+			return handler, c.ArgErr()
+		}
+	}
+	return handler, nil
+}

plugin/errors/setup_test.go

@@ -0,0 +1,45 @@
+package errors
+
+import (
+	"testing"
+
+	"github.com/mholt/caddy"
+)
+
+func TestErrorsParse(t *testing.T) {
+	tests := []struct {
+		inputErrorsRules     string
+		shouldErr            bool
+		expectedErrorHandler errorHandler
+	}{
+		{`errors`, false, errorHandler{
+			LogFile: "stdout",
+		}},
+		{`errors stdout`, false, errorHandler{
+			LogFile: "stdout",
+		}},
+		{`errors errors.txt`, true, errorHandler{
+			LogFile: "",
+		}},
+		{`errors visible`, true, errorHandler{
+			LogFile: "",
+		}},
+		{`errors { log visible }`, true, errorHandler{
+			LogFile: "stdout",
+		}},
+	}
+	for i, test := range tests {
+		c := caddy.NewTestController("dns", test.inputErrorsRules)
+		actualErrorsRule, err := errorsParse(c)
+
+		if err == nil && test.shouldErr {
+			t.Errorf("Test %d didn't error, but it should have", i)
+		} else if err != nil && !test.shouldErr {
+			t.Errorf("Test %d errored, but it shouldn't have; got '%v'", i, err)
+		}
+		if actualErrorsRule.LogFile != test.expectedErrorHandler.LogFile {
+			t.Errorf("Test %d expected LogFile to be %s, but got %s",
+				i, test.expectedErrorHandler.LogFile, actualErrorsRule.LogFile)
+		}
+	}
+}