omaha: add structure for representing a single app update

The protocol structures are intended for representing a collection of
apps and their updates but for a server's internal API and data store we
need to represent a self-contained app update manifest.

omaha/update.go

@@ -0,0 +1,50 @@
+// 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"
+)
+
+// Update is a manifest for a single omaha update response. It extends
+// the standard Manifest protocol element with the application id and
+// previous version which are used to match against the update request.
+// A blank previous version indicates this update can be applied to any
+// existing install. The application id may not be blank.
+type Update struct {
+	XMLName         xml.Name `xml:"update" json:"-"`
+	Id              string   `xml:"appid,attr"`
+	PreviousVersion string   `xml:"previousversion,attr,omitempty"`
+	URL             URL      `xml:"urls>url"`
+	Manifest
+
+	// The delta_okay request attribute is an update_engine extension.
+	RespectDeltaOK bool `xml:"respect_delta_okay,attr,omitempty"`
+}
+
+// The URL attribute in Update is currently assumed to be a relative
+// path which may be found on multiple mirrors. A server using this is
+// expected to know the mirror prefix(s) it can give the client.
+func (u *Update) URLs(prefixes []string) []*URL {
+	urls := make([]*URL, len(prefixes))
+	for i, prefix := range prefixes {
+		urls[i] = &URL{CodeBase: prefix + u.URL.CodeBase}
+	}
+	return urls
+}
+
+type Updater interface {
+	Update(os *OS, app *AppRequest) (*Update, error)
+}

omaha/update_test.go

@@ -0,0 +1,42 @@
+// 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"
+	"testing"
+)
+
+const SampleUpdate = `<?xml version="1.0" encoding="UTF-8"?>
+<update appid="{87efface-864d-49a5-9bb3-4b050a7c227a}" version="9999.0.0">
+ <urls>
+  <url codebase="packages/9999.0.0"></url>
+ </urls>
+ <manifest version="9999.0.0">
+  <packages>
+   <package name="update.gz" hash="+LXvjiaPkeYDLHoNKlf9qbJwvnk=" size="67546213" required="true"></package>
+  </packages>
+</update>
+`
+
+func TestUpdateURLs(t *testing.T) {
+	u := Update{}
+	xml.Unmarshal([]byte(SampleUpdate), &u)
+
+	urls := u.URLs([]string{"http://localhost/updates/"})
+	if urls[0].CodeBase != "http://localhost/updates/packages/9999.0.0" {
+		t.Error("Unexpected URL", urls[0].CodeBase)
+	}
+}