Add StartProxyError for status-report-safe errors, and use for proxy download

src/start-proxy-action.ts

@@ -12,6 +12,7 @@ import { getActionsLogger, Logger } from "./logging";
 import {
   Credential,
   credentialToStr,
+  downloadProxy,
   getCredentials,
   getDownloadUrl,
   parseLanguage,
@@ -238,14 +239,7 @@ async function getProxyBinaryPath(logger: Logger): Promise<string> {
       apiDetails,
       proxyInfo.url,
     );
-    const temp = await toolcache.downloadTool(
-      proxyInfo.url,
-      undefined,
-      authorization,
-      {
-        accept: "application/octet-stream",
-      },
-    );
+    const temp = await downloadProxy(logger, proxyInfo.url, authorization);
     const extracted = await toolcache.extractTar(temp);
     proxyBin = await toolcache.cacheDir(
       extracted,

src/start-proxy.test.ts

@@ -1,3 +1,4 @@
+import * as toolcache from "@actions/tool-cache";
 import test from "ava";
 import sinon from "sinon";
 
@@ -318,3 +319,47 @@ test("credentialToStr - hides passwords/tokens", (t) => {
       .includes(secret),
   );
 });
+
+test("getSafeErrorMessage - returns actual message for `StartProxyError`", (t) => {
+  const error = new startProxyExports.StartProxyError(
+    startProxyExports.StartProxyErrorType.DownloadFailed,
+  );
+  t.is(startProxyExports.getSafeErrorMessage(error), error.message);
+});
+
+test("getSafeErrorMessage - does not return message for arbitrary errors", (t) => {
+  const error = new Error(startProxyExports.StartProxyErrorType.DownloadFailed);
+
+  const message = startProxyExports.getSafeErrorMessage(error);
+
+  t.not(message, error.message);
+  t.assert(message.startsWith("Error from start-proxy Action omitted"));
+  t.assert(message.includes(typeof error));
+});
+
+test("downloadProxy - returns file path on success", async (t) => {
+  const loggedMessages = [];
+  const logger = getRecordingLogger(loggedMessages);
+  const testPath = "/some/path";
+  sinon.stub(toolcache, "downloadTool").resolves(testPath);
+
+  const result = await startProxyExports.downloadProxy(
+    logger,
+    "url",
+    undefined,
+  );
+  t.is(result, testPath);
+});
+
+test("downloadProxy - wraps errors on failure", async (t) => {
+  const loggedMessages = [];
+  const logger = getRecordingLogger(loggedMessages);
+  sinon.stub(toolcache, "downloadTool").throws();
+
+  await t.throwsAsync(
+    startProxyExports.downloadProxy(logger, "url", undefined),
+    {
+      instanceOf: startProxyExports.StartProxyError,
+    },
+  );
+});

src/start-proxy.ts

@@ -1,4 +1,5 @@
 import * as core from "@actions/core";
+import * as toolcache from "@actions/tool-cache";
 
 import { getApiClient } from "./api-client";
 import * as artifactScanner from "./artifact-scanner";
@@ -16,6 +17,26 @@ import {
 import * as util from "./util";
 import { ConfigurationError, getErrorMessage, isDefined } from "./util";
 
+/**
+ * Enumerates specific error types, along with suitable error messages, for errors
+ * that we want to track in status reports.
+ */
+export enum StartProxyErrorType {
+  DownloadFailed = "Failed to download proxy archive.",
+}
+
+/**
+ * We want to avoid accidentally leaking secrets that may be contained in exception
+ * messages in the `start-proxy` action. Consequently, we don't report the messages
+ * of arbitrary exceptions. This type of error ensures that the message is one from
+ * `StartProxyErrorType` and therefore safe to include in a status report.
+ */
+export class StartProxyError extends Error {
+  constructor(errorType: StartProxyErrorType) {
+    super(errorType);
+  }
+}
+
 interface StartProxyStatus extends StatusReportBase {
   // A comma-separated list of registry types which are configured for CodeQL.
   // This only includes registry types we support, not all that are configured.
@@ -53,6 +74,23 @@ export async function sendSuccessStatusReport(
   }
 }
 
+/**
+ * Returns an error message for `error` that can safely be reported in a status report,
+ * i.e. that does not contain sensitive information.
+ *
+ * @param error The error for which to get an error message.
+ */
+export function getSafeErrorMessage(error: Error): string {
+  // If the error is a `StartProxyError`, the constructor ensures that the
+  // message comes from `StartProxyErrorType`.
+  if (error instanceof StartProxyError) {
+    return error.message;
+  }
+
+  // Otherwise, omit the actual error message.
+  return `Error from start-proxy Action omitted (${typeof error}).`;
+}
+
 /**
  * Sends a status report for the `start-proxy` action indicating a failure.
  *
@@ -70,6 +108,8 @@ export async function sendFailedStatusReport(
   const error = util.wrapError(unwrappedError);
   core.setFailed(`start-proxy action failed: ${error.message}`);
 
+  const statusReportMessage = getSafeErrorMessage(error);
+
   // We skip sending the error message and stack trace here to avoid the possibility
   // of leaking any sensitive information into the telemetry.
   const errorStatusReportBase = await createStatusReportBase(
@@ -81,7 +121,7 @@ export async function sendFailedStatusReport(
     },
     await util.checkDiskUsage(logger),
     logger,
-    "Error from start-proxy Action omitted",
+    statusReportMessage,
   );
   if (errorStatusReportBase !== undefined) {
     await sendStatusReport(errorStatusReportBase);
@@ -369,3 +409,28 @@ export function credentialToStr(c: Credential): string {
     c.username
   }; Password: ${c.password !== undefined}; Token: ${c.token !== undefined}`;
 }
+
+/**
+ * Attempts to download a file from `url` into the toolcache.
+ *
+ * @param logger THe logger to use.
+ * @param url The URL to download the proxy binary from.
+ * @param authorization The authorization information to use.
+ * @returns If successful, the path to the downloaded file.
+ */
+export async function downloadProxy(
+  logger: Logger,
+  url: string,
+  authorization: string | undefined,
+) {
+  try {
+    return toolcache.downloadTool(url, undefined, authorization, {
+      accept: "application/octet-stream",
+    });
+  } catch (error) {
+    logger.error(
+      `Failed to download proxy archive from ${url}: ${getErrorMessage(error)}`,
+    );
+    throw new StartProxyError(StartProxyErrorType.DownloadFailed);
+  }
+}