Bug 1945855 - Show error page for 4xx/5xx responses with no content, whether the Content-Length header is missing or lying r=dveditz,necko-reviewers,valentin

Differential Revision: https://phabricator.services.mozilla.com/D240385

browser/base/content/test/about/blank_page.sjs

@@ -25,6 +25,7 @@ function handleRequest(request, response) {
 
   const status = parseInt(params.status);
   const message = params.message;
+  const header = params.header;
 
   // Set default if missing parameters
   if (!status || !message) {
@@ -33,6 +34,15 @@ function handleRequest(request, response) {
     return;
   }
 
+  if (header === "hide") {
+    response.setStatusLine(request.httpVersion, status, message);
+    return;
+  }
+  if (header === "lie") {
+    response.setStatusLine(request.httpVersion, status, message);
+    response.setHeader("Content-Length", "100", false);
+    return;
+  }
   response.setStatusLine(request.httpVersion, status, message);
   response.setHeader("Content-Length", "0", false);
 }

browser/base/content/test/about/browser_aboutNetError_blank_page.js

@@ -17,7 +17,8 @@ async function test_blankPage(
   page,
   expectedL10nID,
   responseStatus,
-  responseStatusText
+  responseStatusText,
+  header = "show" // show (zero content-length), hide (no content-length), or lie (non-empty content-length)
 ) {
   await SpecialPowers.pushPrefEnv({
     set: [["browser.http.blank_page_with_error_response.enabled", false]],
@@ -27,7 +28,7 @@ async function test_blankPage(
   let pageLoaded;
   const uri = `${page}?status=${encodeURIComponent(
     responseStatus
-  )}&message=${encodeURIComponent(responseStatusText)}`;
+  )}&message=${encodeURIComponent(responseStatusText)}&header=${encodeURIComponent(header)}`;
 
   // Simulating loading the page
   await BrowserTestUtils.openNewForegroundTab(
@@ -89,6 +90,46 @@ add_task(async function test_blankPage_5xx() {
   );
 });
 
+add_task(async function test_blankPage_withoutHeader_4xx() {
+  await test_blankPage(
+    BLANK_PAGE,
+    "httpErrorPage-title",
+    400,
+    "Bad Request",
+    "hide"
+  );
+});
+
+add_task(async function test_blankPage_withoutHeader_5xx() {
+  await test_blankPage(
+    BLANK_PAGE,
+    "serverError-title",
+    503,
+    "Service Unavailable",
+    "hide"
+  );
+});
+
+add_task(async function test_blankPage_lyingHeader_4xx() {
+  await test_blankPage(
+    BLANK_PAGE,
+    "httpErrorPage-title",
+    400,
+    "Bad Request",
+    "lie"
+  );
+});
+
+add_task(async function test_blankPage_lyingHeader_5xx() {
+  await test_blankPage(
+    BLANK_PAGE,
+    "serverError-title",
+    503,
+    "Service Unavailable",
+    "lie"
+  );
+});
+
 add_task(async function test_emptyPage_viewSource() {
   await SpecialPowers.pushPrefEnv({
     set: [["browser.http.blank_page_with_error_response.enabled", false]],
@@ -96,7 +137,7 @@ add_task(async function test_emptyPage_viewSource() {
 
   let tab = await BrowserTestUtils.openNewForegroundTab(
     gBrowser,
-    `view-source:${BLANK_PAGE}?status=503&message=Service%20Unavailable`,
+    `view-source:${BLANK_PAGE}?status=503&message=Service%20Unavailable&header=show`,
     true // wait for the load to complete
   );
   let browser = tab.linkedBrowser;

uriloader/base/nsURILoader.cpp

@@ -218,6 +218,7 @@ nsDocumentOpenInfo::OnDataAvailable(nsIRequest* request, nsIInputStream* inStr,
   // if we have retarged to the end stream listener, then forward the call....
   // otherwise, don't do anything
 
+  mReceivedData = true;
   nsresult rv = NS_OK;
 
   if (m_targetStreamListener)
@@ -240,10 +241,64 @@ nsDocumentOpenInfo::OnDataFinished(nsresult aStatus) {
   return NS_OK;
 }
 
+/* static */
+nsresult nsDocumentOpenInfo::CheckContentLengthDiscrepancy(
+    nsIRequest* request) {
+  // Blank page with content length discrepancy is allowed
+  if (mReceivedData ||
+      mozilla::StaticPrefs::
+          browser_http_blank_page_with_error_response_enabled()) {
+    return NS_OK;
+  }
+
+  nsCOMPtr<nsIHttpChannel> httpChannel(do_QueryInterface(request));
+  if (!httpChannel) {
+    return NS_OK;
+  }
+
+  uint64_t decodedBodySize;
+  if (NS_FAILED(httpChannel->GetDecodedBodySize(&decodedBodySize)) ||
+      decodedBodySize != 0) {
+    return NS_OK;
+  }
+
+  nsCOMPtr<nsIURI> uri;
+  if (NS_SUCCEEDED(httpChannel->GetURI(getter_AddRefs(uri))) &&
+      uri->SchemeIs("view-source")) {
+    return NS_OK;
+  }
+
+  uint32_t responseCode = 0;
+  if (NS_SUCCEEDED(httpChannel->GetResponseStatus(&responseCode))) {
+    if (responseCode >= 500) {
+      LOG(
+          ("  Returning NS_ERROR_NET_ERROR_RESPONSE from "
+           "nsDocumentOpenInfo::CheckContentLengthDiscrepancy due to 5xx "
+           "responses with no content"));
+      return NS_ERROR_NET_ERROR_RESPONSE;
+    }
+    if (responseCode >= 400) {
+      LOG(
+          ("  Returning NS_ERROR_NET_EMPTY_RESPONSE from "
+           "nsDocumentOpenInfo::CheckContentLengthDiscrepancy due to 4xx "
+           "responses with no content"));
+      return NS_ERROR_NET_EMPTY_RESPONSE;
+    }
+  }
+  return NS_OK;
+}
+
 NS_IMETHODIMP nsDocumentOpenInfo::OnStopRequest(nsIRequest* request,
                                                 nsresult aStatus) {
   LOG(("[0x%p] nsDocumentOpenInfo::OnStopRequest", this));
 
+  // Bug 1945855 - Show error page for 4xx/5xx responses with no content,
+  // whether the Content-Length header is missing or lying
+  nsresult rv = CheckContentLengthDiscrepancy(request);
+  if (NS_FAILED(rv)) {
+    aStatus = rv;
+  }
+
   if (m_targetStreamListener) {
     nsCOMPtr<nsIStreamListener> listener(m_targetStreamListener);
 

uriloader/base/nsURILoader.h

@@ -80,6 +80,11 @@ class nsDocumentOpenInfo : public nsIThreadRetargetableStreamListener {
    */
   nsresult Prepare();
 
+  // Check for a page with empty body + missing/any content-length.
+  // Return NS_ERROR_NET_ERROR_RESPONSE for 5xx and NS_ERROR_NET_EMPTY_RESPONSE
+  // for 4xx, respectively. Otherwise, return NS_OK.
+  nsresult CheckContentLengthDiscrepancy(nsIRequest* request);
+
   // Call this (from OnStartRequest) to attempt to find an nsIStreamListener to
   // take the data off our hands.
   nsresult DispatchContent(nsIRequest* request);
@@ -213,6 +218,13 @@ class nsDocumentOpenInfo : public nsIThreadRetargetableStreamListener {
    * docshell
    */
   bool mAllowListenerConversions = true;
+
+  /**
+   * Tracks whether any data was received in OnDataAvailable.
+   * Used to detect cases where the response has no Content-Length
+   * header and an empty body.
+   */
+  bool mReceivedData = false;
 };
 
 #endif /* nsURILoader_h__ */