Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

6 files changed, 1577 insertions, 0 deletions

diff --git a/netwerk/protocol/viewsource/moz.build b/netwerk/protocol/viewsource/moz.build
new file mode 100644
index 0000000000..adf19615f0
--- /dev/null
+++ b/netwerk/protocol/viewsource/moz.build
@@ -0,0 +1,29 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+XPIDL_SOURCES += [
+    "nsIViewSourceChannel.idl",
+]
+
+XPIDL_MODULE = "necko_viewsource"
+
+UNIFIED_SOURCES += [
+    "nsViewSourceChannel.cpp",
+    "nsViewSourceHandler.cpp",
+]
+
+EXPORTS += [
+    "nsViewSourceHandler.h",
+]
+
+FINAL_LIBRARY = "xul"
+LOCAL_INCLUDES += [
+    "/netwerk/base",
+    # For nsHttpChannel.h
+    "/netwerk/protocol/http",
+]
+
+include("/ipc/chromium/chromium-config.mozbuild")
diff --git a/netwerk/protocol/viewsource/nsIViewSourceChannel.idl b/netwerk/protocol/viewsource/nsIViewSourceChannel.idl
new file mode 100644
index 0000000000..036142ba3d
--- /dev/null
+++ b/netwerk/protocol/viewsource/nsIViewSourceChannel.idl
@@ -0,0 +1,41 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIChannel.idl"
+
+[uuid(3e9800f8-edb7-4c9a-9285-09b4f045b019)]
+interface nsIViewSourceChannel : nsIChannel
+{
+    /**
+     * The actual (MIME) content type of the data.
+     *
+     * nsIViewSourceChannel returns a content type of
+     * "application/x-view-source" if you ask it for the contentType
+     * attribute.
+     *
+     * However, callers interested in finding out or setting the
+     * actual content type can utilize this attribute.
+     */
+    [must_use] attribute ACString originalContentType;
+
+    /**
+     * Whether the channel was created to view the source of a srcdoc document.
+     */
+    [must_use] readonly attribute boolean isSrcdocChannel;
+
+    /**
+     * Set to indicate the base URI.  If this channel is a srcdoc channel, it
+     * returns the base URI provided by the embedded channel.  It is used to
+     * provide an indication of the base URI in circumstances where it isn't
+     * otherwise recoverable.  Returns null when it isn't set and isn't a
+     * srcdoc channel.
+     */
+    [must_use] attribute nsIURI baseURI;
+
+    /**
+     * Get the inner channel wrapped by this nsIViewSourceChannel.
+     */
+    [notxpcom, nostdcall] nsIChannel getInnerChannel();
+};
diff --git a/netwerk/protocol/viewsource/nsViewSourceChannel.cpp b/netwerk/protocol/viewsource/nsViewSourceChannel.cpp
new file mode 100644
index 0000000000..f2428a5744
--- /dev/null
+++ b/netwerk/protocol/viewsource/nsViewSourceChannel.cpp
@@ -0,0 +1,1220 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=4 sw=2 sts=2 et: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsViewSourceChannel.h"
+#include "mozilla/DebugOnly.h"
+#include "mozilla/NullPrincipal.h"
+#include "nsContentSecurityManager.h"
+#include "nsContentUtils.h"
+#include "nsHttpChannel.h"
+#include "nsIExternalProtocolHandler.h"
+#include "nsIHttpHeaderVisitor.h"
+#include "nsIIOService.h"
+#include "nsIInputStreamChannel.h"
+#include "nsIReferrerInfo.h"
+#include "nsMimeTypes.h"
+#include "nsNetUtil.h"
+#include "nsServiceManagerUtils.h"
+
+NS_IMPL_ADDREF(nsViewSourceChannel)
+NS_IMPL_RELEASE(nsViewSourceChannel)
+/*
+  This QI uses NS_INTERFACE_MAP_ENTRY_CONDITIONAL to check for
+  non-nullness of mHttpChannel, mCachingChannel, and mUploadChannel.
+*/
+NS_INTERFACE_MAP_BEGIN(nsViewSourceChannel)
+  NS_INTERFACE_MAP_ENTRY(nsIViewSourceChannel)
+  NS_INTERFACE_MAP_ENTRY(nsIStreamListener)
+  NS_INTERFACE_MAP_ENTRY(nsIRequestObserver)
+  NS_INTERFACE_MAP_ENTRY(nsIInterfaceRequestor)
+  NS_INTERFACE_MAP_ENTRY(nsIChannelEventSink)
+  NS_INTERFACE_MAP_ENTRY_CONDITIONAL(nsIHttpChannel, mHttpChannel)
+  NS_INTERFACE_MAP_ENTRY_CONDITIONAL(nsIIdentChannel, mHttpChannel)
+  NS_INTERFACE_MAP_ENTRY_CONDITIONAL(nsIHttpChannelInternal,
+                                     mHttpChannelInternal)
+  NS_INTERFACE_MAP_ENTRY_CONDITIONAL(nsICachingChannel, mCachingChannel)
+  NS_INTERFACE_MAP_ENTRY_CONDITIONAL(nsICacheInfoChannel, mCacheInfoChannel)
+  NS_INTERFACE_MAP_ENTRY_CONDITIONAL(nsIUploadChannel, mUploadChannel)
+  NS_INTERFACE_MAP_ENTRY_CONDITIONAL(nsIFormPOSTActionChannel, mPostChannel)
+  NS_INTERFACE_MAP_ENTRY_CONDITIONAL(nsIChildChannel, mChildChannel)
+  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsIRequest, nsIViewSourceChannel)
+  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsIChannel, nsIViewSourceChannel)
+  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIViewSourceChannel)
+NS_INTERFACE_MAP_END
+
+static nsresult WillUseExternalProtocolHandler(nsIIOService* aIOService,
+                                               const char* aScheme) {
+  nsCOMPtr<nsIProtocolHandler> handler;
+  nsresult rv =
+      aIOService->GetProtocolHandler(aScheme, getter_AddRefs(handler));
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  nsCOMPtr<nsIExternalProtocolHandler> externalHandler =
+      do_QueryInterface(handler);
+  // We should not allow view-source to open any external app.
+  if (externalHandler) {
+    NS_WARNING(nsPrintfCString("blocking view-source:%s:", aScheme).get());
+    return NS_ERROR_MALFORMED_URI;
+  }
+
+  return NS_OK;
+}
+
+nsresult nsViewSourceChannel::Init(nsIURI* uri, nsILoadInfo* aLoadInfo) {
+  mOriginalURI = uri;
+
+  nsAutoCString path;
+  nsresult rv = uri->GetPathQueryRef(path);
+  if (NS_FAILED(rv)) return rv;
+
+  nsCOMPtr<nsIIOService> pService(do_GetIOService(&rv));
+  if (NS_FAILED(rv)) return rv;
+
+  nsAutoCString scheme;
+  rv = pService->ExtractScheme(path, scheme);
+  if (NS_FAILED(rv)) return rv;
+
+  // prevent viewing source of javascript URIs (see bug 204779)
+  if (scheme.EqualsLiteral("javascript")) {
+    NS_WARNING("blocking view-source:javascript:");
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  rv = WillUseExternalProtocolHandler(pService, scheme.get());
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  nsCOMPtr<nsIURI> newChannelURI;
+  rv = pService->NewURI(path, nullptr, nullptr, getter_AddRefs(newChannelURI));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  rv = pService->NewChannelFromURIWithLoadInfo(newChannelURI, aLoadInfo,
+                                               getter_AddRefs(mChannel));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  mIsSrcdocChannel = false;
+
+  mChannel->SetOriginalURI(mOriginalURI);
+  UpdateChannelInterfaces();
+
+  return NS_OK;
+}
+
+nsresult nsViewSourceChannel::InitSrcdoc(nsIURI* aURI, nsIURI* aBaseURI,
+                                         const nsAString& aSrcdoc,
+                                         nsILoadInfo* aLoadInfo) {
+  nsresult rv;
+
+  nsCOMPtr<nsIURI> inStreamURI;
+  // Need to strip view-source: from the URI.  Hardcoded to
+  // about:srcdoc as this is the only permissible URI for srcdoc
+  // loads
+  rv = NS_NewURI(getter_AddRefs(inStreamURI), u"about:srcdoc"_ns);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  rv = NS_NewInputStreamChannelInternal(getter_AddRefs(mChannel), inStreamURI,
+                                        aSrcdoc, "text/html"_ns, aLoadInfo,
+                                        true);
+
+  NS_ENSURE_SUCCESS(rv, rv);
+  mOriginalURI = aURI;
+  mIsSrcdocChannel = true;
+
+  mChannel->SetOriginalURI(mOriginalURI);
+  UpdateChannelInterfaces();
+
+  rv = UpdateLoadInfoResultPrincipalURI();
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  nsCOMPtr<nsIInputStreamChannel> isc = do_QueryInterface(mChannel);
+  MOZ_ASSERT(isc);
+  isc->SetBaseURI(aBaseURI);
+  return NS_OK;
+}
+
+void nsViewSourceChannel::UpdateChannelInterfaces() {
+  mHttpChannel = do_QueryInterface(mChannel);
+  mHttpChannelInternal = do_QueryInterface(mChannel);
+  mCachingChannel = do_QueryInterface(mChannel);
+  mCacheInfoChannel = do_QueryInterface(mChannel);
+  mUploadChannel = do_QueryInterface(mChannel);
+  mPostChannel = do_QueryInterface(mChannel);
+  mChildChannel = do_QueryInterface(mChannel);
+}
+
+void nsViewSourceChannel::ReleaseListeners() {
+  mListener = nullptr;
+  mCallbacks = nullptr;
+}
+
+nsresult nsViewSourceChannel::UpdateLoadInfoResultPrincipalURI() {
+  nsresult rv;
+
+  MOZ_ASSERT(mChannel);
+
+  nsCOMPtr<nsILoadInfo> channelLoadInfo = mChannel->LoadInfo();
+  nsCOMPtr<nsIURI> channelResultPrincipalURI;
+  rv = channelLoadInfo->GetResultPrincipalURI(
+      getter_AddRefs(channelResultPrincipalURI));
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  if (!channelResultPrincipalURI) {
+    mChannel->GetOriginalURI(getter_AddRefs(channelResultPrincipalURI));
+    return NS_OK;
+  }
+
+  if (!channelResultPrincipalURI) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  bool alreadyViewSource;
+  if (NS_SUCCEEDED(channelResultPrincipalURI->SchemeIs("view-source",
+                                                       &alreadyViewSource)) &&
+      alreadyViewSource) {
+    return NS_OK;
+  }
+
+  nsCOMPtr<nsIURI> updatedResultPrincipalURI;
+  rv = BuildViewSourceURI(channelResultPrincipalURI,
+                          getter_AddRefs(updatedResultPrincipalURI));
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  rv = channelLoadInfo->SetResultPrincipalURI(updatedResultPrincipalURI);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  return NS_OK;
+}
+
+nsresult nsViewSourceChannel::BuildViewSourceURI(nsIURI* aURI,
+                                                 nsIURI** aResult) {
+  nsresult rv;
+
+  // protect ourselves against broken channel implementations
+  if (!aURI) {
+    NS_ERROR("no URI to build view-source uri!");
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  nsAutoCString spec;
+  rv = aURI->GetSpec(spec);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  return NS_NewURI(aResult, "view-source:"_ns + spec);
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// nsIRequest methods:
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetName(nsACString& result) {
+  nsCOMPtr<nsIURI> uri;
+  GetURI(getter_AddRefs(uri));
+  if (uri) {
+    return uri->GetSpec(result);
+  }
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetTransferSize(uint64_t* aTransferSize) {
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetRequestSize(uint64_t* aRequestSize) {
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetDecodedBodySize(uint64_t* aDecodedBodySize) {
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetEncodedBodySize(uint64_t* aEncodedBodySize) {
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::IsPending(bool* result) {
+  NS_ENSURE_TRUE(mChannel, NS_ERROR_FAILURE);
+
+  return mChannel->IsPending(result);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetStatus(nsresult* status) {
+  NS_ENSURE_TRUE(mChannel, NS_ERROR_FAILURE);
+
+  return mChannel->GetStatus(status);
+}
+
+NS_IMETHODIMP nsViewSourceChannel::SetCanceledReason(
+    const nsACString& aReason) {
+  return nsIViewSourceChannel::SetCanceledReasonImpl(aReason);
+}
+
+NS_IMETHODIMP nsViewSourceChannel::GetCanceledReason(nsACString& aReason) {
+  return nsIViewSourceChannel::GetCanceledReasonImpl(aReason);
+}
+
+NS_IMETHODIMP nsViewSourceChannel::CancelWithReason(nsresult aStatus,
+                                                    const nsACString& aReason) {
+  return nsIViewSourceChannel::CancelWithReasonImpl(aStatus, aReason);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::Cancel(nsresult status) {
+  NS_ENSURE_TRUE(mChannel, NS_ERROR_FAILURE);
+
+  return mChannel->Cancel(status);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetCanceled(bool* aCanceled) {
+  NS_ENSURE_TRUE(mChannel, NS_ERROR_FAILURE);
+
+  return mChannel->GetCanceled(aCanceled);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::Suspend(void) {
+  NS_ENSURE_TRUE(mChannel, NS_ERROR_FAILURE);
+
+  return mChannel->Suspend();
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::Resume(void) {
+  NS_ENSURE_TRUE(mChannel, NS_ERROR_FAILURE);
+
+  return mChannel->Resume();
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// nsIChannel methods:
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetOriginalURI(nsIURI** aURI) {
+  *aURI = do_AddRef(mOriginalURI).take();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::SetOriginalURI(nsIURI* aURI) {
+  NS_ENSURE_ARG_POINTER(aURI);
+  mOriginalURI = aURI;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetURI(nsIURI** aURI) {
+  NS_ENSURE_TRUE(mChannel, NS_ERROR_FAILURE);
+
+  nsCOMPtr<nsIURI> uri;
+  nsresult rv = mChannel->GetURI(getter_AddRefs(uri));
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  return BuildViewSourceURI(uri, aURI);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::Open(nsIInputStream** aStream) {
+  NS_ENSURE_TRUE(mChannel, NS_ERROR_FAILURE);
+  return Open(aStream);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::AsyncOpen(nsIStreamListener* aListener) {
+  // We can't ensure GetInitialSecurityCheckDone here
+
+  NS_ENSURE_TRUE(mChannel, NS_ERROR_FAILURE);
+
+  mListener = aListener;
+
+  /*
+   * We want to add ourselves to the loadgroup before opening
+   * mChannel, since we want to make sure we're in the loadgroup
+   * when mChannel finishes and fires OnStopRequest()
+   */
+
+  nsCOMPtr<nsILoadGroup> loadGroup;
+  mChannel->GetLoadGroup(getter_AddRefs(loadGroup));
+  if (loadGroup) {
+    loadGroup->AddRequest(static_cast<nsIViewSourceChannel*>(this), nullptr);
+  }
+
+  nsresult rv = NS_OK;
+  rv = mChannel->AsyncOpen(this);
+
+  if (NS_FAILED(rv) && loadGroup) {
+    loadGroup->RemoveRequest(static_cast<nsIViewSourceChannel*>(this), nullptr,
+                             rv);
+  }
+
+  if (NS_SUCCEEDED(rv)) {
+    // We do this here to make sure all notification callbacks changes have been
+    // made first before we inject this view-source channel.
+    mChannel->GetNotificationCallbacks(getter_AddRefs(mCallbacks));
+    mChannel->SetNotificationCallbacks(this);
+
+    MOZ_ASSERT(mCallbacks != this, "We have a cycle");
+
+    mOpened = true;
+  }
+
+  if (NS_FAILED(rv)) {
+    ReleaseListeners();
+  }
+
+  return rv;
+}
+
+/*
+ * Both the view source channel and mChannel are added to the
+ * loadgroup.  There should never be more than one request in the
+ * loadgroup that has LOAD_DOCUMENT_URI set.  The one that has this
+ * flag set is the request whose URI is used to refetch the document,
+ * so it better be the viewsource channel.
+ *
+ * Therefore, we need to make sure that
+ * 1) The load flags on mChannel _never_ include LOAD_DOCUMENT_URI
+ * 2) The load flags on |this| include LOAD_DOCUMENT_URI when it was
+ *    set via SetLoadFlags (mIsDocument keeps track of this flag).
+ */
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetLoadFlags(uint32_t* aLoadFlags) {
+  NS_ENSURE_TRUE(mChannel, NS_ERROR_FAILURE);
+
+  nsresult rv = mChannel->GetLoadFlags(aLoadFlags);
+  if (NS_FAILED(rv)) return rv;
+
+  // This should actually be just LOAD_DOCUMENT_URI but the win32 compiler
+  // fails to deal due to amiguous inheritance.  nsIChannel::LOAD_DOCUMENT_URI
+  // also fails; the Win32 compiler thinks that's supposed to be a method.
+  if (mIsDocument) *aLoadFlags |= ::nsIChannel::LOAD_DOCUMENT_URI;
+
+  return rv;
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::SetLoadFlags(uint32_t aLoadFlags) {
+  NS_ENSURE_TRUE(mChannel, NS_ERROR_FAILURE);
+
+  // "View source" always wants the currently cached content.
+  // We also want to have _this_ channel, not mChannel to be the
+  // 'document' channel in the loadgroup.
+
+  // These should actually be just LOAD_FROM_CACHE and LOAD_DOCUMENT_URI but
+  // the win32 compiler fails to deal due to amiguous inheritance.
+  // nsIChannel::LOAD_DOCUMENT_URI/nsIRequest::LOAD_FROM_CACHE also fails; the
+  // Win32 compiler thinks that's supposed to be a method.
+  mIsDocument = (aLoadFlags & ::nsIChannel::LOAD_DOCUMENT_URI) != 0;
+
+  nsresult rv =
+      mChannel->SetLoadFlags((aLoadFlags | ::nsIRequest::LOAD_FROM_CACHE) &
+                             ~::nsIChannel::LOAD_DOCUMENT_URI);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  if (mHttpChannel) {
+    rv = mHttpChannel->SetIsMainDocumentChannel(
+        aLoadFlags & ::nsIChannel::LOAD_DOCUMENT_URI);
+    MOZ_ASSERT(NS_SUCCEEDED(rv));
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetTRRMode(nsIRequest::TRRMode* aTRRMode) {
+  return nsIViewSourceChannel::GetTRRModeImpl(aTRRMode);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::SetTRRMode(nsIRequest::TRRMode aTRRMode) {
+  return nsIViewSourceChannel::SetTRRModeImpl(aTRRMode);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetContentType(nsACString& aContentType) {
+  NS_ENSURE_TRUE(mChannel, NS_ERROR_FAILURE);
+
+  aContentType.Truncate();
+
+  if (mContentType.IsEmpty()) {
+    // Get the current content type
+    nsresult rv;
+    nsAutoCString contentType;
+    rv = mChannel->GetContentType(contentType);
+    if (NS_FAILED(rv)) return rv;
+
+    // If we don't know our type, just say so.  The unknown
+    // content decoder will then kick in automatically, and it
+    // will call our SetOriginalContentType method instead of our
+    // SetContentType method to set the type it determines.
+    if (!contentType.EqualsLiteral(UNKNOWN_CONTENT_TYPE) &&
+        !contentType.IsEmpty()) {
+      contentType = VIEWSOURCE_CONTENT_TYPE;
+    }
+
+    mContentType = contentType;
+  }
+
+  aContentType = mContentType;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::SetContentType(const nsACString& aContentType) {
+  // Our GetContentType() currently returns VIEWSOURCE_CONTENT_TYPE
+  //
+  // However, during the parsing phase the parser calls our
+  // channel's GetContentType(). Returning the string above trips up
+  // the parser. In order to avoid messy changes and not to have the
+  // parser depend on nsIViewSourceChannel Vidur proposed the
+  // following solution:
+  //
+  // The ViewSourceChannel initially returns a content type of
+  // VIEWSOURCE_CONTENT_TYPE.  Based on this type decisions to
+  // create a viewer for doing a view source are made.  After the
+  // viewer is created, nsLayoutDLF::CreateInstance() calls this
+  // SetContentType() with the original content type.  When it's
+  // time for the parser to find out the content type it will call
+  // our channel's GetContentType() and it will get the original
+  // content type, such as, text/html and everything is kosher from
+  // then on.
+
+  if (!mOpened) {
+    // We do not take hints
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  mContentType = aContentType;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetContentCharset(nsACString& aContentCharset) {
+  NS_ENSURE_TRUE(mChannel, NS_ERROR_FAILURE);
+
+  return mChannel->GetContentCharset(aContentCharset);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::SetContentCharset(const nsACString& aContentCharset) {
+  NS_ENSURE_TRUE(mChannel, NS_ERROR_FAILURE);
+
+  return mChannel->SetContentCharset(aContentCharset);
+}
+
+// We don't forward these methods becacuse content-disposition isn't whitelisted
+// (see GetResponseHeader/VisitResponseHeaders).
+NS_IMETHODIMP
+nsViewSourceChannel::GetContentDisposition(uint32_t* aContentDisposition) {
+  return NS_ERROR_NOT_AVAILABLE;
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::SetContentDisposition(uint32_t aContentDisposition) {
+  return NS_ERROR_NOT_AVAILABLE;
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetContentDispositionFilename(
+    nsAString& aContentDispositionFilename) {
+  return NS_ERROR_NOT_AVAILABLE;
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::SetContentDispositionFilename(
+    const nsAString& aContentDispositionFilename) {
+  return NS_ERROR_NOT_AVAILABLE;
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetContentDispositionHeader(
+    nsACString& aContentDispositionHeader) {
+  return NS_ERROR_NOT_AVAILABLE;
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetContentLength(int64_t* aContentLength) {
+  NS_ENSURE_TRUE(mChannel, NS_ERROR_FAILURE);
+
+  return mChannel->GetContentLength(aContentLength);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::SetContentLength(int64_t aContentLength) {
+  NS_ENSURE_TRUE(mChannel, NS_ERROR_FAILURE);
+
+  return mChannel->SetContentLength(aContentLength);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetLoadGroup(nsILoadGroup** aLoadGroup) {
+  NS_ENSURE_TRUE(mChannel, NS_ERROR_FAILURE);
+
+  return mChannel->GetLoadGroup(aLoadGroup);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::SetLoadGroup(nsILoadGroup* aLoadGroup) {
+  NS_ENSURE_TRUE(mChannel, NS_ERROR_FAILURE);
+
+  return mChannel->SetLoadGroup(aLoadGroup);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetOwner(nsISupports** aOwner) {
+  NS_ENSURE_TRUE(mChannel, NS_ERROR_FAILURE);
+
+  return mChannel->GetOwner(aOwner);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::SetOwner(nsISupports* aOwner) {
+  NS_ENSURE_TRUE(mChannel, NS_ERROR_FAILURE);
+
+  return mChannel->SetOwner(aOwner);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetLoadInfo(nsILoadInfo** aLoadInfo) {
+  NS_ENSURE_TRUE(mChannel, NS_ERROR_FAILURE);
+
+  return mChannel->GetLoadInfo(aLoadInfo);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::SetLoadInfo(nsILoadInfo* aLoadInfo) {
+  NS_ENSURE_TRUE(mChannel, NS_ERROR_FAILURE);
+  MOZ_RELEASE_ASSERT(aLoadInfo, "loadinfo can't be null");
+  return mChannel->SetLoadInfo(aLoadInfo);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetIsDocument(bool* aIsDocument) {
+  NS_ENSURE_TRUE(mChannel, NS_ERROR_FAILURE);
+
+  return mChannel->GetIsDocument(aIsDocument);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetNotificationCallbacks(
+    nsIInterfaceRequestor** aNotificationCallbacks) {
+  NS_ENSURE_TRUE(mChannel, NS_ERROR_FAILURE);
+
+  return mChannel->GetNotificationCallbacks(aNotificationCallbacks);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::SetNotificationCallbacks(
+    nsIInterfaceRequestor* aNotificationCallbacks) {
+  NS_ENSURE_TRUE(mChannel, NS_ERROR_FAILURE);
+
+  return mChannel->SetNotificationCallbacks(aNotificationCallbacks);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetSecurityInfo(nsITransportSecurityInfo** aSecurityInfo) {
+  NS_ENSURE_TRUE(mChannel, NS_ERROR_FAILURE);
+
+  return mChannel->GetSecurityInfo(aSecurityInfo);
+}
+
+// nsIViewSourceChannel methods
+NS_IMETHODIMP
+nsViewSourceChannel::GetOriginalContentType(nsACString& aContentType) {
+  NS_ENSURE_TRUE(mChannel, NS_ERROR_FAILURE);
+
+  return mChannel->GetContentType(aContentType);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::SetOriginalContentType(const nsACString& aContentType) {
+  NS_ENSURE_TRUE(mChannel, NS_ERROR_FAILURE);
+
+  // clear our cached content-type value
+  mContentType.Truncate();
+
+  return mChannel->SetContentType(aContentType);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetIsSrcdocChannel(bool* aIsSrcdocChannel) {
+  *aIsSrcdocChannel = mIsSrcdocChannel;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetBaseURI(nsIURI** aBaseURI) {
+  if (mIsSrcdocChannel) {
+    nsCOMPtr<nsIInputStreamChannel> isc = do_QueryInterface(mChannel);
+    if (isc) {
+      return isc->GetBaseURI(aBaseURI);
+    }
+  }
+  *aBaseURI = do_AddRef(mBaseURI).take();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::SetBaseURI(nsIURI* aBaseURI) {
+  mBaseURI = aBaseURI;
+  return NS_OK;
+}
+
+nsIChannel* nsViewSourceChannel::GetInnerChannel() { return mChannel; }
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetProtocolVersion(nsACString& aProtocolVersion) {
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+// nsIRequestObserver methods
+NS_IMETHODIMP
+nsViewSourceChannel::OnStartRequest(nsIRequest* aRequest) {
+  NS_ENSURE_TRUE(mListener, NS_ERROR_FAILURE);
+  // The channel may have gotten redirected... Time to update our info
+  mChannel = do_QueryInterface(aRequest);
+  UpdateChannelInterfaces();
+
+  nsresult rv = UpdateLoadInfoResultPrincipalURI();
+  if (NS_FAILED(rv)) {
+    Cancel(rv);
+  }
+
+  return mListener->OnStartRequest(static_cast<nsIViewSourceChannel*>(this));
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::OnStopRequest(nsIRequest* aRequest, nsresult aStatus) {
+  NS_ENSURE_TRUE(mListener, NS_ERROR_FAILURE);
+  if (mChannel) {
+    nsCOMPtr<nsILoadGroup> loadGroup;
+    mChannel->GetLoadGroup(getter_AddRefs(loadGroup));
+    if (loadGroup) {
+      loadGroup->RemoveRequest(static_cast<nsIViewSourceChannel*>(this),
+                               nullptr, aStatus);
+    }
+  }
+
+  nsresult rv = mListener->OnStopRequest(
+      static_cast<nsIViewSourceChannel*>(this), aStatus);
+
+  ReleaseListeners();
+
+  return rv;
+}
+
+// nsIStreamListener methods
+NS_IMETHODIMP
+nsViewSourceChannel::OnDataAvailable(nsIRequest* aRequest,
+                                     nsIInputStream* aInputStream,
+                                     uint64_t aSourceOffset, uint32_t aLength) {
+  NS_ENSURE_TRUE(mListener, NS_ERROR_FAILURE);
+  return mListener->OnDataAvailable(static_cast<nsIViewSourceChannel*>(this),
+                                    aInputStream, aSourceOffset, aLength);
+}
+
+// nsIHttpChannel methods
+
+// We want to forward most of nsIHttpChannel over to mHttpChannel, but we want
+// to override GetRequestHeader and VisitHeaders. The reason is that we don't
+// want various headers like Link: and Refresh: applying to view-source.
+NS_IMETHODIMP
+nsViewSourceChannel::GetChannelId(uint64_t* aChannelId) {
+  NS_ENSURE_ARG_POINTER(aChannelId);
+  return !mHttpChannel ? NS_ERROR_NULL_POINTER
+                       : mHttpChannel->GetChannelId(aChannelId);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::SetChannelId(uint64_t aChannelId) {
+  return !mHttpChannel ? NS_ERROR_NULL_POINTER
+                       : mHttpChannel->SetChannelId(aChannelId);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetTopLevelContentWindowId(uint64_t* aWindowId) {
+  return !mHttpChannel ? NS_ERROR_NULL_POINTER
+                       : mHttpChannel->GetTopLevelContentWindowId(aWindowId);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::SetTopLevelContentWindowId(uint64_t aWindowId) {
+  return !mHttpChannel ? NS_ERROR_NULL_POINTER
+                       : mHttpChannel->SetTopLevelContentWindowId(aWindowId);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetBrowserId(uint64_t* aId) {
+  return !mHttpChannel ? NS_ERROR_NULL_POINTER
+                       : mHttpChannel->GetBrowserId(aId);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::SetBrowserId(uint64_t aId) {
+  return !mHttpChannel ? NS_ERROR_NULL_POINTER
+                       : mHttpChannel->SetBrowserId(aId);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetRequestMethod(nsACString& aRequestMethod) {
+  return !mHttpChannel ? NS_ERROR_NULL_POINTER
+                       : mHttpChannel->GetRequestMethod(aRequestMethod);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::SetRequestMethod(const nsACString& aRequestMethod) {
+  return !mHttpChannel ? NS_ERROR_NULL_POINTER
+                       : mHttpChannel->SetRequestMethod(aRequestMethod);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetReferrerInfo(nsIReferrerInfo** aReferrerInfo) {
+  return !mHttpChannel ? NS_ERROR_NULL_POINTER
+                       : mHttpChannel->GetReferrerInfo(aReferrerInfo);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::SetReferrerInfo(nsIReferrerInfo* aReferrerInfo) {
+  return !mHttpChannel ? NS_ERROR_NULL_POINTER
+                       : mHttpChannel->SetReferrerInfo(aReferrerInfo);
+}
+
+NS_IMETHODIMP nsViewSourceChannel::SetReferrerInfoWithoutClone(
+    nsIReferrerInfo* aReferrerInfo) {
+  return !mHttpChannel
+             ? NS_ERROR_NULL_POINTER
+             : mHttpChannel->SetReferrerInfoWithoutClone(aReferrerInfo);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetRequestHeader(const nsACString& aHeader,
+                                      nsACString& aValue) {
+  aValue.Truncate();
+  return !mHttpChannel ? NS_ERROR_NULL_POINTER
+                       : mHttpChannel->GetRequestHeader(aHeader, aValue);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::SetRequestHeader(const nsACString& aHeader,
+                                      const nsACString& aValue, bool aMerge) {
+  return !mHttpChannel
+             ? NS_ERROR_NULL_POINTER
+             : mHttpChannel->SetRequestHeader(aHeader, aValue, aMerge);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::SetNewReferrerInfo(
+    const nsACString& aUrl, nsIReferrerInfo::ReferrerPolicyIDL aPolicy,
+    bool aSendReferrer) {
+  return !mHttpChannel
+             ? NS_ERROR_NULL_POINTER
+             : mHttpChannel->SetNewReferrerInfo(aUrl, aPolicy, aSendReferrer);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::SetEmptyRequestHeader(const nsACString& aHeader) {
+  return !mHttpChannel ? NS_ERROR_NULL_POINTER
+                       : mHttpChannel->SetEmptyRequestHeader(aHeader);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::VisitRequestHeaders(nsIHttpHeaderVisitor* aVisitor) {
+  return !mHttpChannel ? NS_ERROR_NULL_POINTER
+                       : mHttpChannel->VisitRequestHeaders(aVisitor);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::VisitNonDefaultRequestHeaders(
+    nsIHttpHeaderVisitor* aVisitor) {
+  return !mHttpChannel ? NS_ERROR_NULL_POINTER
+                       : mHttpChannel->VisitNonDefaultRequestHeaders(aVisitor);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::ShouldStripRequestBodyHeader(const nsACString& aMethod,
+                                                  bool* aResult) {
+  return !mHttpChannel
+             ? NS_ERROR_NULL_POINTER
+             : mHttpChannel->ShouldStripRequestBodyHeader(aMethod, aResult);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetAllowSTS(bool* aAllowSTS) {
+  return !mHttpChannel ? NS_ERROR_NULL_POINTER
+                       : mHttpChannel->GetAllowSTS(aAllowSTS);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::SetAllowSTS(bool aAllowSTS) {
+  return !mHttpChannel ? NS_ERROR_NULL_POINTER
+                       : mHttpChannel->SetAllowSTS(aAllowSTS);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetRedirectionLimit(uint32_t* aRedirectionLimit) {
+  return !mHttpChannel ? NS_ERROR_NULL_POINTER
+                       : mHttpChannel->GetRedirectionLimit(aRedirectionLimit);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::SetRedirectionLimit(uint32_t aRedirectionLimit) {
+  return !mHttpChannel ? NS_ERROR_NULL_POINTER
+                       : mHttpChannel->SetRedirectionLimit(aRedirectionLimit);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetResponseStatus(uint32_t* aResponseStatus) {
+  return !mHttpChannel ? NS_ERROR_NULL_POINTER
+                       : mHttpChannel->GetResponseStatus(aResponseStatus);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetResponseStatusText(nsACString& aResponseStatusText) {
+  return !mHttpChannel
+             ? NS_ERROR_NULL_POINTER
+             : mHttpChannel->GetResponseStatusText(aResponseStatusText);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetRequestSucceeded(bool* aRequestSucceeded) {
+  return !mHttpChannel ? NS_ERROR_NULL_POINTER
+                       : mHttpChannel->GetRequestSucceeded(aRequestSucceeded);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetResponseHeader(const nsACString& aHeader,
+                                       nsACString& aValue) {
+  aValue.Truncate();
+  if (!mHttpChannel) return NS_ERROR_NULL_POINTER;
+
+  if (!aHeader.Equals("Content-Type"_ns, nsCaseInsensitiveCStringComparator) &&
+      !aHeader.Equals("Content-Security-Policy"_ns,
+                      nsCaseInsensitiveCStringComparator) &&
+      !aHeader.Equals("Content-Security-Policy-Report-Only"_ns,
+                      nsCaseInsensitiveCStringComparator) &&
+      !aHeader.Equals("X-Frame-Options"_ns,
+                      nsCaseInsensitiveCStringComparator)) {
+    // We simulate the NS_ERROR_NOT_AVAILABLE error which is produced by
+    // GetResponseHeader via nsHttpHeaderArray::GetHeader when the entry is
+    // not present, such that it appears as though no headers except for the
+    // whitelisted ones were set on this channel.
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  return mHttpChannel->GetResponseHeader(aHeader, aValue);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::SetResponseHeader(const nsACString& header,
+                                       const nsACString& value, bool merge) {
+  return !mHttpChannel ? NS_ERROR_NULL_POINTER
+                       : mHttpChannel->SetResponseHeader(header, value, merge);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::VisitResponseHeaders(nsIHttpHeaderVisitor* aVisitor) {
+  if (!mHttpChannel) return NS_ERROR_NULL_POINTER;
+
+  constexpr auto contentTypeStr = "Content-Type"_ns;
+  nsAutoCString contentType;
+  nsresult rv = mHttpChannel->GetResponseHeader(contentTypeStr, contentType);
+  if (NS_SUCCEEDED(rv)) {
+    return aVisitor->VisitHeader(contentTypeStr, contentType);
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetOriginalResponseHeader(const nsACString& aHeader,
+                                               nsIHttpHeaderVisitor* aVisitor) {
+  nsAutoCString value;
+  nsresult rv = GetResponseHeader(aHeader, value);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  return aVisitor->VisitHeader(aHeader, value);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::VisitOriginalResponseHeaders(
+    nsIHttpHeaderVisitor* aVisitor) {
+  return VisitResponseHeaders(aVisitor);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::IsNoStoreResponse(bool* _retval) {
+  return !mHttpChannel ? NS_ERROR_NULL_POINTER
+                       : mHttpChannel->IsNoStoreResponse(_retval);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::IsNoCacheResponse(bool* _retval) {
+  return !mHttpChannel ? NS_ERROR_NULL_POINTER
+                       : mHttpChannel->IsNoCacheResponse(_retval);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::IsPrivateResponse(bool* _retval) {
+  return !mHttpChannel ? NS_ERROR_NULL_POINTER
+                       : mHttpChannel->IsPrivateResponse(_retval);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::RedirectTo(nsIURI* uri) {
+  return !mHttpChannel ? NS_ERROR_NULL_POINTER : mHttpChannel->RedirectTo(uri);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::UpgradeToSecure() {
+  return !mHttpChannel ? NS_ERROR_NULL_POINTER
+                       : mHttpChannel->UpgradeToSecure();
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetRequestContextID(uint64_t* _retval) {
+  return !mHttpChannel ? NS_ERROR_NULL_POINTER
+                       : mHttpChannel->GetRequestContextID(_retval);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::SetRequestContextID(uint64_t rcid) {
+  return !mHttpChannel ? NS_ERROR_NULL_POINTER
+                       : mHttpChannel->SetRequestContextID(rcid);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetIsMainDocumentChannel(bool* aValue) {
+  return !mHttpChannel ? NS_ERROR_NULL_POINTER
+                       : mHttpChannel->GetIsMainDocumentChannel(aValue);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::SetIsMainDocumentChannel(bool aValue) {
+  return !mHttpChannel ? NS_ERROR_NULL_POINTER
+                       : mHttpChannel->SetIsMainDocumentChannel(aValue);
+}
+
+NS_IMETHODIMP nsViewSourceChannel::SetClassicScriptHintCharset(
+    const nsAString& aClassicScriptHintCharset) {
+  return !mHttpChannel ? NS_ERROR_NULL_POINTER
+                       : mHttpChannel->SetClassicScriptHintCharset(
+                             aClassicScriptHintCharset);
+}
+
+NS_IMETHODIMP nsViewSourceChannel::GetClassicScriptHintCharset(
+    nsAString& aClassicScriptHintCharset) {
+  return !mHttpChannel ? NS_ERROR_NULL_POINTER
+                       : mHttpChannel->GetClassicScriptHintCharset(
+                             aClassicScriptHintCharset);
+}
+
+NS_IMETHODIMP nsViewSourceChannel::SetDocumentCharacterSet(
+    const nsAString& aDocumentCharacterSet) {
+  return !mHttpChannel
+             ? NS_ERROR_NULL_POINTER
+             : mHttpChannel->SetDocumentCharacterSet(aDocumentCharacterSet);
+}
+
+NS_IMETHODIMP nsViewSourceChannel::GetDocumentCharacterSet(
+    nsAString& aDocumentCharacterSet) {
+  return !mHttpChannel
+             ? NS_ERROR_NULL_POINTER
+             : mHttpChannel->GetDocumentCharacterSet(aDocumentCharacterSet);
+}
+// Have to manually forward SetCorsPreflightParameters since it's [notxpcom]
+void nsViewSourceChannel::SetCorsPreflightParameters(
+    const nsTArray<nsCString>& aUnsafeHeaders,
+    bool aShouldStripRequestBodyHeader) {
+  mHttpChannelInternal->SetCorsPreflightParameters(
+      aUnsafeHeaders, aShouldStripRequestBodyHeader);
+}
+
+void nsViewSourceChannel::SetAltDataForChild(bool aIsForChild) {
+  mHttpChannelInternal->SetAltDataForChild(aIsForChild);
+}
+
+void nsViewSourceChannel::DisableAltDataCache() {
+  mHttpChannelInternal->DisableAltDataCache();
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::LogBlockedCORSRequest(const nsAString& aMessage,
+                                           const nsACString& aCategory,
+                                           bool aIsWarning) {
+  if (!mHttpChannel) {
+    NS_WARNING(
+        "nsViewSourceChannel::LogBlockedCORSRequest mHttpChannel is null");
+    return NS_ERROR_UNEXPECTED;
+  }
+  return mHttpChannel->LogBlockedCORSRequest(aMessage, aCategory, aIsWarning);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::LogMimeTypeMismatch(const nsACString& aMessageName,
+                                         bool aWarning, const nsAString& aURL,
+                                         const nsAString& aContentType) {
+  if (!mHttpChannel) {
+    NS_WARNING("nsViewSourceChannel::LogMimeTypeMismatch mHttpChannel is null");
+    return NS_ERROR_UNEXPECTED;
+  }
+  return mHttpChannel->LogMimeTypeMismatch(aMessageName, aWarning, aURL,
+                                           aContentType);
+}
+
+// FIXME: Should this forward to mHttpChannel? This was previously handled by a
+// default empty implementation.
+void nsViewSourceChannel::SetSource(
+    mozilla::UniquePtr<mozilla::ProfileChunkedBuffer> aSource) {}
+
+const nsTArray<mozilla::net::PreferredAlternativeDataTypeParams>&
+nsViewSourceChannel::PreferredAlternativeDataTypes() {
+  if (mCacheInfoChannel) {
+    return mCacheInfoChannel->PreferredAlternativeDataTypes();
+  }
+  return mEmptyArray;
+}
+
+void nsViewSourceChannel::DoDiagnosticAssertWhenOnStopNotCalledOnDestroy() {
+  if (mHttpChannelInternal) {
+    mHttpChannelInternal->DoDiagnosticAssertWhenOnStopNotCalledOnDestroy();
+  }
+}
+
+// FIXME: Should this forward to mHttpChannelInternal? This was previously
+// handled by a default empty implementation.
+void nsViewSourceChannel::SetConnectionInfo(
+    mozilla::net::nsHttpConnectionInfo* aInfo) {}
+
+// nsIChildChannel methods
+
+NS_IMETHODIMP
+nsViewSourceChannel::ConnectParent(uint32_t aRegistarId) {
+  NS_ENSURE_TRUE(mChildChannel, NS_ERROR_NULL_POINTER);
+
+  return mChildChannel->ConnectParent(aRegistarId);
+}
+
+NS_IMETHODIMP
+nsViewSourceChannel::CompleteRedirectSetup(nsIStreamListener* aListener) {
+  NS_ENSURE_TRUE(mChildChannel, NS_ERROR_NULL_POINTER);
+
+  mListener = aListener;
+
+  /*
+   * We want to add ourselves to the loadgroup before opening
+   * mChannel, since we want to make sure we're in the loadgroup
+   * when mChannel finishes and fires OnStopRequest()
+   */
+
+  nsCOMPtr<nsILoadGroup> loadGroup;
+  mChannel->GetLoadGroup(getter_AddRefs(loadGroup));
+  if (loadGroup) {
+    loadGroup->AddRequest(static_cast<nsIViewSourceChannel*>(this), nullptr);
+  }
+
+  nsresult rv = NS_OK;
+  rv = mChildChannel->CompleteRedirectSetup(this);
+
+  if (NS_FAILED(rv) && loadGroup) {
+    loadGroup->RemoveRequest(static_cast<nsIViewSourceChannel*>(this), nullptr,
+                             rv);
+  }
+
+  if (NS_SUCCEEDED(rv)) {
+    mOpened = true;
+  }
+
+  return rv;
+}
+
+// nsIChannelEventSink
+
+NS_IMETHODIMP
+nsViewSourceChannel::AsyncOnChannelRedirect(
+    nsIChannel* oldChannel, nsIChannel* newChannel, uint32_t flags,
+    nsIAsyncVerifyRedirectCallback* callback) {
+  nsresult rv;
+
+  // We want consumers of the new inner channel be able to recognize it's
+  // actually used for view-source.  Hence we modify its original URI here.
+  // This will not affect security checks because those have already been
+  // synchronously done before our event sink is called.  Note that result
+  // principal URI is still modified at the OnStartRequest notification.
+  nsCOMPtr<nsIURI> newChannelOrigURI;
+  rv = newChannel->GetOriginalURI(getter_AddRefs(newChannelOrigURI));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  nsAutoCString scheme;
+  rv = newChannelOrigURI->GetScheme(scheme);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  nsCOMPtr<nsIIOService> ioService(do_GetIOService(&rv));
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  rv = WillUseExternalProtocolHandler(ioService, scheme.get());
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  nsCOMPtr<nsIURI> newChannelUpdatedOrigURI;
+  rv = BuildViewSourceURI(newChannelOrigURI,
+                          getter_AddRefs(newChannelUpdatedOrigURI));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  rv = newChannel->SetOriginalURI(newChannelUpdatedOrigURI);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  nsCOMPtr<nsIChannelEventSink> sink(do_QueryInterface(mCallbacks));
+  if (sink) {
+    return sink->AsyncOnChannelRedirect(oldChannel, newChannel, flags,
+                                        callback);
+  }
+
+  callback->OnRedirectVerifyCallback(NS_OK);
+  return NS_OK;
+}
+
+// nsIInterfaceRequestor
+
+NS_IMETHODIMP
+nsViewSourceChannel::GetInterface(const nsIID& aIID, void** aResult) {
+  if (aIID.Equals(NS_GET_IID(nsIChannelEventSink))) {
+    nsCOMPtr<nsIChannelEventSink> self(this);
+    self.forget(aResult);
+    return NS_OK;
+  }
+
+  if (mCallbacks) {
+    return mCallbacks->GetInterface(aIID, aResult);
+  }
+
+  return NS_ERROR_NO_INTERFACE;
+}
diff --git a/netwerk/protocol/viewsource/nsViewSourceChannel.h b/netwerk/protocol/viewsource/nsViewSourceChannel.h
new file mode 100644
index 0000000000..87c490f6b7
--- /dev/null
+++ b/netwerk/protocol/viewsource/nsViewSourceChannel.h
@@ -0,0 +1,98 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsViewSourceChannel_h___
+#define nsViewSourceChannel_h___
+
+#include "mozilla/Attributes.h"
+#include "mozilla/net/NeckoChannelParams.h"
+#include "nsCOMPtr.h"
+#include "nsICachingChannel.h"
+#include "nsIChannelEventSink.h"
+#include "nsIFormPOSTActionChannel.h"
+#include "nsIHttpChannel.h"
+#include "nsIHttpChannelInternal.h"
+#include "nsIInterfaceRequestor.h"
+#include "nsIStreamListener.h"
+#include "nsIURI.h"
+#include "nsIViewSourceChannel.h"
+#include "nsIChildChannel.h"
+#include "nsString.h"
+
+class nsViewSourceChannel final : public nsIViewSourceChannel,
+                                  public nsIStreamListener,
+                                  public nsIHttpChannel,
+                                  public nsIHttpChannelInternal,
+                                  public nsICachingChannel,
+                                  public nsIFormPOSTActionChannel,
+                                  public nsIChildChannel,
+                                  public nsIInterfaceRequestor,
+                                  public nsIChannelEventSink {
+ public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIREQUEST
+  NS_DECL_NSICHANNEL
+  NS_DECL_NSIIDENTCHANNEL
+  NS_DECL_NSIVIEWSOURCECHANNEL
+  NS_DECL_NSISTREAMLISTENER
+  NS_DECL_NSIREQUESTOBSERVER
+  NS_DECL_NSIHTTPCHANNEL
+  NS_DECL_NSICHILDCHANNEL
+  NS_DECL_NSIINTERFACEREQUESTOR
+  NS_DECL_NSICHANNELEVENTSINK
+  NS_FORWARD_SAFE_NSICACHEINFOCHANNEL(mCacheInfoChannel)
+  NS_FORWARD_SAFE_NSICACHINGCHANNEL(mCachingChannel)
+  NS_FORWARD_SAFE_NSIUPLOADCHANNEL(mUploadChannel)
+  NS_FORWARD_SAFE_NSIFORMPOSTACTIONCHANNEL(mPostChannel)
+  NS_FORWARD_SAFE_NSIHTTPCHANNELINTERNAL(mHttpChannelInternal)
+
+  // nsViewSourceChannel methods:
+  nsViewSourceChannel() = default;
+
+  [[nodiscard]] nsresult Init(nsIURI* uri, nsILoadInfo* aLoadInfo);
+
+  [[nodiscard]] nsresult InitSrcdoc(nsIURI* aURI, nsIURI* aBaseURI,
+                                    const nsAString& aSrcdoc,
+                                    nsILoadInfo* aLoadInfo);
+
+  // Updates or sets the result principal URI of the underlying channel's
+  // loadinfo to be prefixed with the "view-source:" schema as:
+  //
+  // mChannel.loadInfo.resultPrincipalURI = "view-source:" +
+  //    (mChannel.loadInfo.resultPrincipalURI | mChannel.orignalURI);
+  nsresult UpdateLoadInfoResultPrincipalURI();
+
+ protected:
+  ~nsViewSourceChannel() = default;
+  void ReleaseListeners();
+
+  nsTArray<mozilla::net::PreferredAlternativeDataTypeParams> mEmptyArray;
+
+  // Clones aURI and prefixes it with "view-source:" schema,
+  nsresult BuildViewSourceURI(nsIURI* aURI, nsIURI** aResult);
+
+  // Called to update the forwarding channel members after the `mChannel` field
+  // has been changed to reflect the new inner channel.
+  void UpdateChannelInterfaces();
+
+  nsCOMPtr<nsIInterfaceRequestor> mCallbacks;
+  nsCOMPtr<nsIChannel> mChannel;
+  nsCOMPtr<nsIHttpChannel> mHttpChannel;
+  nsCOMPtr<nsIHttpChannelInternal> mHttpChannelInternal;
+  nsCOMPtr<nsICachingChannel> mCachingChannel;
+  nsCOMPtr<nsICacheInfoChannel> mCacheInfoChannel;
+  nsCOMPtr<nsIUploadChannel> mUploadChannel;
+  nsCOMPtr<nsIFormPOSTActionChannel> mPostChannel;
+  nsCOMPtr<nsIChildChannel> mChildChannel;
+  nsCOMPtr<nsIStreamListener> mListener;
+  nsCOMPtr<nsIURI> mOriginalURI;
+  nsCOMPtr<nsIURI> mBaseURI;
+  nsCString mContentType;
+  bool mIsDocument{false};  // keeps track of the LOAD_DOCUMENT_URI flag
+  bool mOpened{false};
+  bool mIsSrcdocChannel{false};
+};
+
+#endif /* nsViewSourceChannel_h___ */
diff --git a/netwerk/protocol/viewsource/nsViewSourceHandler.cpp b/netwerk/protocol/viewsource/nsViewSourceHandler.cpp
new file mode 100644
index 0000000000..f7b440d4d7
--- /dev/null
+++ b/netwerk/protocol/viewsource/nsViewSourceHandler.cpp
@@ -0,0 +1,141 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=4 sw=2 sts=2 et: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsViewSourceHandler.h"
+#include "nsViewSourceChannel.h"
+#include "nsNetUtil.h"
+#include "nsSimpleNestedURI.h"
+
+#define VIEW_SOURCE "view-source"
+
+#define DEFAULT_FLAGS \
+  (URI_NORELATIVE | URI_NOAUTH | URI_DANGEROUS_TO_LOAD | URI_NON_PERSISTABLE)
+
+namespace mozilla {
+namespace net {
+
+////////////////////////////////////////////////////////////////////////////////
+
+NS_IMPL_ISUPPORTS(nsViewSourceHandler, nsIProtocolHandler,
+                  nsIProtocolHandlerWithDynamicFlags)
+
+////////////////////////////////////////////////////////////////////////////////
+// nsIProtocolHandler methods:
+
+NS_IMETHODIMP
+nsViewSourceHandler::GetScheme(nsACString& result) {
+  result.AssignLiteral(VIEW_SOURCE);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsViewSourceHandler::GetFlagsForURI(nsIURI* aURI, uint32_t* result) {
+  *result = DEFAULT_FLAGS;
+  nsCOMPtr<nsINestedURI> nestedURI(do_QueryInterface(aURI));
+  if (!nestedURI) {
+    return NS_OK;
+  }
+
+  nsCOMPtr<nsIURI> innerURI;
+  nestedURI->GetInnerURI(getter_AddRefs(innerURI));
+  nsCOMPtr<nsINetUtil> netUtil = do_GetNetUtil();
+  bool isLoadable = false;
+  nsresult rv =
+      netUtil->ProtocolHasFlags(innerURI, URI_LOADABLE_BY_ANYONE, &isLoadable);
+  NS_ENSURE_SUCCESS(rv, rv);
+  if (isLoadable) {
+    *result |= URI_LOADABLE_BY_EXTENSIONS;
+  }
+  return NS_OK;
+}
+
+// static
+nsresult nsViewSourceHandler::CreateNewURI(const nsACString& aSpec,
+                                           const char* aCharset,
+                                           nsIURI* aBaseURI, nsIURI** aResult) {
+  *aResult = nullptr;
+
+  // Extract inner URL and normalize to ASCII.  This is done to properly
+  // support IDN in cases like "view-source:http://www.szalagavató.hu/"
+
+  int32_t colon = aSpec.FindChar(':');
+  if (colon == kNotFound) return NS_ERROR_MALFORMED_URI;
+
+  nsCOMPtr<nsIURI> innerURI;
+  nsresult rv = NS_NewURI(getter_AddRefs(innerURI), Substring(aSpec, colon + 1),
+                          aCharset, aBaseURI);
+  if (NS_FAILED(rv)) return rv;
+
+  nsAutoCString asciiSpec;
+  rv = innerURI->GetAsciiSpec(asciiSpec);
+  if (NS_FAILED(rv)) return rv;
+
+  // put back our scheme and construct a simple-uri wrapper
+
+  asciiSpec.Insert(VIEW_SOURCE ":", 0);
+
+  nsCOMPtr<nsIURI> uri;
+  rv = NS_MutateURI(new nsSimpleNestedURI::Mutator())
+           .Apply(&nsINestedURIMutator::Init, innerURI)
+           .SetSpec(asciiSpec)
+           .Finalize(uri);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  uri.swap(*aResult);
+  return rv;
+}
+
+NS_IMETHODIMP
+nsViewSourceHandler::NewChannel(nsIURI* uri, nsILoadInfo* aLoadInfo,
+                                nsIChannel** result) {
+  NS_ENSURE_ARG_POINTER(uri);
+  RefPtr<nsViewSourceChannel> channel = new nsViewSourceChannel();
+
+  nsresult rv = channel->Init(uri, aLoadInfo);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  *result = channel.forget().downcast<nsIViewSourceChannel>().take();
+  return NS_OK;
+}
+
+nsresult nsViewSourceHandler::NewSrcdocChannel(nsIURI* aURI, nsIURI* aBaseURI,
+                                               const nsAString& aSrcdoc,
+                                               nsILoadInfo* aLoadInfo,
+                                               nsIChannel** outChannel) {
+  NS_ENSURE_ARG_POINTER(aURI);
+  RefPtr<nsViewSourceChannel> channel = new nsViewSourceChannel();
+
+  nsresult rv = channel->InitSrcdoc(aURI, aBaseURI, aSrcdoc, aLoadInfo);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  *outChannel = static_cast<nsIViewSourceChannel*>(channel.forget().take());
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsViewSourceHandler::AllowPort(int32_t port, const char* scheme,
+                               bool* _retval) {
+  // don't override anything.
+  *_retval = false;
+  return NS_OK;
+}
+
+nsViewSourceHandler::nsViewSourceHandler() { gInstance = this; }
+
+nsViewSourceHandler::~nsViewSourceHandler() { gInstance = nullptr; }
+
+nsViewSourceHandler* nsViewSourceHandler::gInstance = nullptr;
+
+nsViewSourceHandler* nsViewSourceHandler::GetInstance() { return gInstance; }
+
+}  // namespace net
+}  // namespace mozilla
diff --git a/netwerk/protocol/viewsource/nsViewSourceHandler.h b/netwerk/protocol/viewsource/nsViewSourceHandler.h
new file mode 100644
index 0000000000..b9e9f3ab7c
--- /dev/null
+++ b/netwerk/protocol/viewsource/nsViewSourceHandler.h
@@ -0,0 +1,48 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsViewSourceHandler_h___
+#define nsViewSourceHandler_h___
+
+#include "nsIProtocolHandler.h"
+#include "nsNetUtil.h"
+#include "mozilla/Attributes.h"
+
+class nsILoadInfo;
+
+namespace mozilla {
+namespace net {
+
+class nsViewSourceHandler final : public nsIProtocolHandlerWithDynamicFlags,
+                                  public nsIProtocolHandler {
+ public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIPROTOCOLHANDLER
+  NS_DECL_NSIPROTOCOLHANDLERWITHDYNAMICFLAGS
+
+  nsViewSourceHandler();
+
+  // Creates a new nsViewSourceChannel to view the source of an about:srcdoc
+  // URI with contents specified by srcdoc.
+  [[nodiscard]] nsresult NewSrcdocChannel(nsIURI* aURI, nsIURI* aBaseURI,
+                                          const nsAString& aSrcdoc,
+                                          nsILoadInfo* aLoadInfo,
+                                          nsIChannel** outChannel);
+
+  static nsViewSourceHandler* GetInstance();
+
+  static nsresult CreateNewURI(const nsACString& aSpec, const char* aCharset,
+                               nsIURI* aBaseURI, nsIURI** aResult);
+
+ private:
+  ~nsViewSourceHandler();
+
+  static nsViewSourceHandler* gInstance;
+};
+
+}  // namespace net
+}  // namespace mozilla
+
+#endif /* !defined( nsViewSourceHandler_h___ ) */