omaha: add complete http handler implementation

The handler is driven by something implementing the 'Updater' interface.

omaha/handler.go

@@ -0,0 +1,134 @@
+// Copyright 2015 CoreOS, 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 omaha
+
+import (
+	"encoding/xml"
+	"log"
+	"net/http"
+)
+
+type OmahaHandler struct {
+	Updater
+}
+
+func (o *OmahaHandler) ServeHTTP(w http.ResponseWriter, httpReq *http.Request) {
+	if httpReq.Method != "POST" {
+		log.Printf("omaha: Unexpected HTTP method: %s", httpReq.Method)
+		http.Error(w, "Expected a POST", http.StatusBadRequest)
+		return
+	}
+
+	// A request over 1M in size is certainly bogus.
+	reader := http.MaxBytesReader(w, httpReq.Body, 1024*1024)
+
+	decoder := xml.NewDecoder(reader)
+	var omahaReq Request
+	if err := decoder.Decode(&omahaReq); err != nil {
+		log.Printf("omaha: Failed decoding XML: %v", err)
+		http.Error(w, "Invalid XML", http.StatusBadRequest)
+		return
+	}
+
+	if omahaReq.Protocol != "3.0" {
+		log.Printf("omaha: Unexpected protocol: %q", omahaReq.Protocol)
+		http.Error(w, "Omaha 3.0 Required", http.StatusBadRequest)
+		return
+	}
+
+	httpStatus := 0
+	omahaResp := NewResponse()
+	for _, appReq := range omahaReq.Apps {
+		appResp := o.serveApp(omahaResp, httpReq, &omahaReq, appReq)
+		if appResp.Status == AppOK {
+			// HTTP is ok if any app is ok.
+			httpStatus = http.StatusOK
+		} else if httpStatus == 0 {
+			// If no app is ok HTTP will use the first error.
+			if appResp.Status == AppInternalError {
+				httpStatus = http.StatusInternalServerError
+			} else {
+				httpStatus = http.StatusBadRequest
+			}
+		}
+	}
+
+	if httpStatus == 0 {
+		httpStatus = http.StatusBadRequest
+	}
+
+	w.Header().Set("Content-Type", "text/xml; charset=utf-8")
+	w.WriteHeader(httpStatus)
+
+	if _, err := w.Write([]byte(xml.Header)); err != nil {
+		log.Printf("omaha: Failed writing response: %v", err)
+		return
+	}
+
+	encoder := xml.NewEncoder(w)
+	encoder.Indent("", "\t")
+	if err := encoder.Encode(omahaResp); err != nil {
+		log.Printf("omaha: Failed encoding response: %v", err)
+	}
+}
+
+func (o *OmahaHandler) serveApp(omahaResp *Response, httpReq *http.Request, omahaReq *Request, appReq *AppRequest) *AppResponse {
+	if err := o.CheckApp(omahaReq, appReq); err != nil {
+		if appStatus, ok := err.(AppStatus); ok {
+			return omahaResp.AddApp(appReq.Id, appStatus)
+		}
+		log.Printf("omaha: CheckApp failed: %v", err)
+		return omahaResp.AddApp(appReq.Id, AppInternalError)
+	}
+
+	appResp := omahaResp.AddApp(appReq.Id, AppOK)
+	if appReq.UpdateCheck != nil {
+		o.checkUpdate(appResp, httpReq, omahaReq, appReq)
+	}
+
+	if appReq.Ping != nil {
+		o.Ping(omahaReq, appReq)
+		appResp.AddPing()
+	}
+
+	for _, event := range appReq.Events {
+		o.Event(omahaReq, appReq, event)
+		appResp.AddEvent()
+	}
+
+	return appResp
+}
+
+func (o *OmahaHandler) checkUpdate(appResp *AppResponse, httpReq *http.Request, omahaReq *Request, appReq *AppRequest) {
+	update, err := o.CheckUpdate(omahaReq, appReq)
+	if err != nil {
+		if updateStatus, ok := err.(UpdateStatus); ok {
+			appResp.AddUpdateCheck(updateStatus)
+		} else {
+			log.Printf("omaha: CheckUpdate failed: %v", err)
+			appResp.AddUpdateCheck(UpdateInternalError)
+		}
+	} else if update != nil {
+		u := appResp.AddUpdateCheck(UpdateOK)
+		fillUpdate(u, update, httpReq)
+	} else {
+		appResp.AddUpdateCheck(NoUpdate)
+	}
+}
+
+func fillUpdate(u *UpdateResponse, update *Update, httpReq *http.Request) {
+	u.URLs = update.URLs([]string{"http://" + httpReq.Host})
+	u.Manifest = &update.Manifest
+}

omaha/handler_test.go

@@ -0,0 +1,68 @@
+// Copyright 2013-2015 CoreOS, 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 omaha
+
+import (
+	"encoding/xml"
+	"fmt"
+	"testing"
+
+	"github.com/kylelemons/godebug/diff"
+)
+
+const (
+	testAppId  = "{27BD862E-8AE8-4886-A055-F7F1A6460627}"
+	testAppVer = "1.0.0"
+)
+
+var (
+	nilRequest  *Request
+	nilResponse *Response
+)
+
+func init() {
+	nilRequest = NewRequest()
+	nilRequest.AddApp(testAppId, testAppVer)
+	nilResponse = NewResponse()
+	nilResponse.AddApp(testAppId, AppOK)
+}
+
+func compareXML(a, b interface{}) error {
+	aXml, err := xml.MarshalIndent(a, "", "\t")
+	if err != nil {
+		return err
+	}
+
+	bXml, err := xml.MarshalIndent(b, "", "\t")
+	if err != nil {
+		return err
+	}
+
+	if d := diff.Diff(string(aXml), string(bXml)); d != "" {
+		err := fmt.Errorf("Unexpected XML:\n%s", d)
+		return err
+	}
+
+	return nil
+}
+
+func TestHandleNilRequest(t *testing.T) {
+	handler := OmahaHandler{UpdaterStub{}}
+	response := NewResponse()
+	handler.serveApp(response, nil, nilRequest, nilRequest.Apps[0])
+	if err := compareXML(nilResponse, response); err != nil {
+		t.Error(err)
+	}
+}

omaha/update.go

@@ -45,6 +45,29 @@ func (u *Update) URLs(prefixes []string) []*URL {
 	return urls
 }
 
+// Updater provides a common interface for any backend that can respond to
+// update requests made to an Omaha server.
 type Updater interface {
-	Update(os *OS, app *AppRequest) (*Update, error)
+	CheckApp(req *Request, app *AppRequest) error
+	CheckUpdate(req *Request, app *AppRequest) (*Update, error)
+	Event(req *Request, app *AppRequest, event *EventRequest)
+	Ping(req *Request, app *AppRequest)
+}
+
+type UpdaterStub struct{}
+
+func (u UpdaterStub) CheckApp(req *Request, app *AppRequest) error {
+	return nil
+}
+
+func (u UpdaterStub) CheckUpdate(req *Request, app *AppRequest) (*Update, error) {
+	return nil, NoUpdate
+}
+
+func (u UpdaterStub) Event(req *Request, app *AppRequest, event *EventRequest) {
+	return
+}
+
+func (u UpdaterStub) Ping(req *Request, app *AppRequest) {
+	return
 }