Add secure automatic agent updates

agent_test.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"os"
 	"testing"
 	"time"
 )
@@ -27,6 +28,31 @@ func TestAgentEnrollmentTokenIsSingleUse(t *testing.T) {
 	}
 }
 
+func TestCurrentAgentUpdateManifestMatchesExecutable(t *testing.T) {
+	manifest, path, err := currentAgentUpdate()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if manifest.URL != "/api/agent/binary" || len(manifest.SHA256) != 64 {
+		t.Fatalf("unexpected manifest: %#v", manifest)
+	}
+	if _, err = os.Stat(path); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestAgentOnlyInstallsNewerVersion(t *testing.T) {
+	if !newerAgentVersion("v0.14.0", "v0.13.0") {
+		t.Fatal("new version was not detected")
+	}
+	if newerAgentVersion("v0.12.0", "v0.13.0") {
+		t.Fatal("downgrade was allowed")
+	}
+	if newerAgentVersion("v0.13.0", "v0.13.0") {
+		t.Fatal("same version was offered")
+	}
+}
+
 func TestAgentReportAuthenticationAndOfflineState(t *testing.T) {
 	store, err := openStore(":memory:")
 	if err != nil {