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/whoami/README.md

@@ -0,0 +1,44 @@
+# whoami
+
+*whoami* returns your resolver's local IP address, port and transport. Your IP address is returned
+ in the additional section as either an A or AAAA record.
+
+The reply always has an empty answer section. The port and transport are included in the additional
+section as a SRV record, transport can be "tcp" or "udp".
+
+~~~ txt
+._<transport>.qname. 0 IN SRV 0 0 <port> .
+~~~
+
+If CoreDNS can't find a Corefile on startup this is the *default* plugin that gets loaded. As
+such it can be used to check that CoreDNS is responding to queries. Other than that this plugin
+is of limited use in production.
+
+The *whoami* plugin will respond to every A or AAAA query, regardless of the query name.
+
+## Syntax
+
+~~~ txt
+whoami
+~~~
+
+## Examples
+
+Start a server on the default port and load the *whoami* plugin.
+
+~~~ corefile
+. {
+    whoami
+}
+~~~
+
+When queried for "example.org A", CoreDNS will respond with:
+
+~~~ txt
+;; QUESTION SECTION:
+;example.org.   IN       A
+
+;; ADDITIONAL SECTION:
+example.org.            0       IN      A       10.240.0.1
+_udp.example.org.       0       IN      SRV     0 0 40212
+~~~

plugin/whoami/setup.go

@@ -0,0 +1,28 @@
+package whoami
+
+import (
+	"github.com/coredns/coredns/core/dnsserver"
+	"github.com/coredns/coredns/plugin"
+
+	"github.com/mholt/caddy"
+)
+
+func init() {
+	caddy.RegisterPlugin("whoami", caddy.Plugin{
+		ServerType: "dns",
+		Action:     setupWhoami,
+	})
+}
+
+func setupWhoami(c *caddy.Controller) error {
+	c.Next() // 'whoami'
+	if c.NextArg() {
+		return plugin.Error("whoami", c.ArgErr())
+	}
+
+	dnsserver.GetConfig(c).AddPlugin(func(next plugin.Handler) plugin.Handler {
+		return Whoami{}
+	})
+
+	return nil
+}

plugin/whoami/setup_test.go

@@ -0,0 +1,19 @@
+package whoami
+
+import (
+	"testing"
+
+	"github.com/mholt/caddy"
+)
+
+func TestSetupWhoami(t *testing.T) {
+	c := caddy.NewTestController("dns", `whoami`)
+	if err := setupWhoami(c); err != nil {
+		t.Fatalf("Expected no errors, but got: %v", err)
+	}
+
+	c = caddy.NewTestController("dns", `whoami example.org`)
+	if err := setupWhoami(c); err == nil {
+		t.Fatalf("Expected errors, but got: %v", err)
+	}
+}

plugin/whoami/whoami.go

@@ -0,0 +1,57 @@
+// Package whoami implements a plugin that returns details about the resolving
+// querying it.
+package whoami
+
+import (
+	"net"
+	"strconv"
+
+	"github.com/coredns/coredns/request"
+
+	"github.com/miekg/dns"
+	"golang.org/x/net/context"
+)
+
+// Whoami is a plugin that returns your IP address, port and the protocol used for connecting
+// to CoreDNS.
+type Whoami struct{}
+
+// ServeDNS implements the plugin.Handler interface.
+func (wh Whoami) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
+	state := request.Request{W: w, Req: r}
+
+	a := new(dns.Msg)
+	a.SetReply(r)
+	a.Compress = true
+	a.Authoritative = true
+
+	ip := state.IP()
+	var rr dns.RR
+
+	switch state.Family() {
+	case 1:
+		rr = new(dns.A)
+		rr.(*dns.A).Hdr = dns.RR_Header{Name: state.QName(), Rrtype: dns.TypeA, Class: state.QClass()}
+		rr.(*dns.A).A = net.ParseIP(ip).To4()
+	case 2:
+		rr = new(dns.AAAA)
+		rr.(*dns.AAAA).Hdr = dns.RR_Header{Name: state.QName(), Rrtype: dns.TypeAAAA, Class: state.QClass()}
+		rr.(*dns.AAAA).AAAA = net.ParseIP(ip)
+	}
+
+	srv := new(dns.SRV)
+	srv.Hdr = dns.RR_Header{Name: "_" + state.Proto() + "." + state.QName(), Rrtype: dns.TypeSRV, Class: state.QClass()}
+	port, _ := strconv.Atoi(state.Port())
+	srv.Port = uint16(port)
+	srv.Target = "."
+
+	a.Extra = []dns.RR{rr, srv}
+
+	state.SizeAndDo(a)
+	w.WriteMsg(a)
+
+	return 0, nil
+}
+
+// Name implements the Handler interface.
+func (wh Whoami) Name() string { return "whoami" }

plugin/whoami/whoami_test.go

@@ -0,0 +1,56 @@
+package whoami
+
+import (
+	"testing"
+
+	"github.com/coredns/coredns/plugin/pkg/dnsrecorder"
+	"github.com/coredns/coredns/plugin/test"
+
+	"github.com/miekg/dns"
+	"golang.org/x/net/context"
+)
+
+func TestWhoami(t *testing.T) {
+	wh := Whoami{}
+
+	tests := []struct {
+		qname         string
+		qtype         uint16
+		expectedCode  int
+		expectedReply []string // ownernames for the records in the additional section.
+		expectedErr   error
+	}{
+		{
+			qname:         "example.org",
+			qtype:         dns.TypeA,
+			expectedCode:  dns.RcodeSuccess,
+			expectedReply: []string{"example.org.", "_udp.example.org."},
+			expectedErr:   nil,
+		},
+	}
+
+	ctx := context.TODO()
+
+	for i, tc := range tests {
+		req := new(dns.Msg)
+		req.SetQuestion(dns.Fqdn(tc.qname), tc.qtype)
+
+		rec := dnsrecorder.New(&test.ResponseWriter{})
+		code, err := wh.ServeDNS(ctx, rec, req)
+
+		if err != tc.expectedErr {
+			t.Errorf("Test %d: Expected error %v, but got %v", i, tc.expectedErr, err)
+		}
+		if code != int(tc.expectedCode) {
+			t.Errorf("Test %d: Expected status code %d, but got %d", i, tc.expectedCode, code)
+		}
+		if len(tc.expectedReply) != 0 {
+			for i, expected := range tc.expectedReply {
+				actual := rec.Msg.Extra[i].Header().Name
+				if actual != expected {
+					t.Errorf("Test %d: Expected answer %s, but got %s", i, expected, actual)
+				}
+			}
+		}
+	}
+}