cmd/dhcp4d: refactor for testing, add /lease/ test

cmd/dhcp4d/dhcp4d.go

@@ -17,6 +17,7 @@ package main
 
 import (
 	"bytes"
+	"context"
 	"encoding/json"
 	"flag"
 	"fmt"
@@ -27,6 +28,7 @@ import (
 	"net/http"
 	"os"
 	"os/signal"
+	"path/filepath"
 	"sort"
 	"strings"
 	"sync"
@@ -220,10 +222,15 @@ func updateListeners() error {
 	return nil
 }
 
-func logic() error {
+type srv struct {
+	errs   chan error
+	leases func(newLeases []*dhcp4d.Lease, latest *dhcp4d.Lease)
+}
+
+func newSrv(permDir string) (*srv, error) {
 	http.Handle("/metrics", promhttp.Handler())
 	if err := updateListeners(); err != nil {
-		return err
+		return nil, err
 	}
 	go func() {
 		ch := make(chan os.Signal, 1)
@@ -235,20 +242,20 @@ func logic() error {
 		}
 	}()
 
-	if err := os.MkdirAll("/perm/dhcp4d", 0755); err != nil {
-		return err
+	if err := os.MkdirAll(filepath.Join(permDir, "dhcp4d"), 0755); err != nil {
+		return nil, err
 	}
 	errs := make(chan error)
 	ifc, err := net.InterfaceByName(*iface)
 	if err != nil {
-		return err
+		return nil, err
 	}
-	handler, err := dhcp4d.NewHandler("/perm", ifc, *iface, nil)
+	handler, err := dhcp4d.NewHandler(permDir, ifc, *iface, nil)
 	if err != nil {
-		return err
+		return nil, err
 	}
-	if err := loadLeases(handler, "/perm/dhcp4d/leases.json"); err != nil {
-		return err
+	if err := loadLeases(handler, filepath.Join(permDir, "dhcp4d/leases.json")); err != nil {
+		return nil, err
 	}
 
 	http.HandleFunc("/lease/", func(w http.ResponseWriter, r *http.Request) {
@@ -356,7 +363,7 @@ func logic() error {
 		if err := json.Indent(&out, b, "", "\t"); err == nil {
 			b = out.Bytes()
 		}
-		if err := renameio.WriteFile("/perm/dhcp4d/leases.json", out.Bytes(), 0644); err != nil {
+		if err := renameio.WriteFile(filepath.Join(permDir, "dhcp4d/leases.json"), out.Bytes(), 0644); err != nil {
 			errs <- err
 		}
 		updateNonExpired(leases)
@@ -366,18 +373,34 @@ func logic() error {
 	}
 	conn, err := conn.NewUDP4BoundListener(*iface, ":67")
 	if err != nil {
-		return err
+		return nil, err
 	}
 	go func() {
 		errs <- dhcp4.Serve(conn, handler)
 	}()
-	return <-errs
+	return &srv{
+		errs,
+		handler.Leases,
+	}, nil
+}
+
+func (s *srv) run(ctx context.Context) error {
+	select {
+	case <-ctx.Done():
+		return ctx.Err()
+	case err := <-s.errs:
+		return err
+	}
 }
 
 func main() {
 	// TODO: drop privileges, run as separate uid?
 	flag.Parse()
-	if err := logic(); err != nil {
+	srv, err := newSrv("/perm")
+	if err != nil {
+		log.Fatal(err)
+	}
+	if err := srv.run(context.Background()); err != nil {
 		log.Fatal(err)
 	}
 }

cmd/dhcp4d/dhcp4d_test.go

@@ -0,0 +1,99 @@
+// Copyright 2019 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"flag"
+	"io/ioutil"
+	"net"
+	"net/http"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/rtr7/router7/internal/dhcp4d"
+	"golang.org/x/sync/errgroup"
+)
+
+const interfacesJson = `
+{
+    "interfaces": [
+        {
+            "name": "lo",
+            "addr": "192.0.2.1/24"
+        }
+    ]
+}
+`
+
+func TestLeaseHandler(t *testing.T) {
+	flag.Set("interface", "lo")
+	ctx, canc := context.WithCancel(context.Background())
+	defer canc()
+	tmp, err := ioutil.TempDir("", "dhcp4dtest")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(tmp)
+	if err := ioutil.WriteFile(filepath.Join(tmp, "interfaces.json"), []byte(interfacesJson), 0644); err != nil {
+		t.Fatal(err)
+	}
+	srv, err := newSrv(tmp)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var eg errgroup.Group
+	eg.Go(func() error { return srv.run(ctx) })
+	lease := dhcp4d.Lease{
+		Num:          74,
+		Addr:         net.ParseIP("10.0.0.76"),
+		HardwareAddr: "02:73:53:00:ca:fe",
+		Hostname:     "midna",
+		Expiry:       time.Now().Add(20 * time.Minute),
+	}
+	srv.leases([]*dhcp4d.Lease{&lease}, &lease)
+	req, err := http.NewRequest("GET", "http://localhost:8067/lease/midna", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got, want := resp.StatusCode, http.StatusOK; got != want {
+		b, _ := ioutil.ReadAll(resp.Body)
+		t.Fatalf("unexpected HTTP response code: got %v (%s), want %v", resp.Status, strings.TrimSpace(string(b)), want)
+	}
+	b, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var got dhcp4d.Lease
+	if err := json.Unmarshal(b, &got); err != nil {
+		t.Fatal(err)
+	}
+	if diff := cmp.Diff(lease, got); diff != "" {
+		t.Fatalf("/lease/midna: unexpected lease: diff (-want +got):\n%s", diff)
+	}
+	canc()
+	if err := eg.Wait(); err != nil && err != context.Canceled {
+		t.Fatal(err)
+	}
+}