1 files changed, 184 insertions, 0 deletions
diff --git a/netwerk/protocol/http/EarlyHintsService.cpp b/netwerk/protocol/http/EarlyHintsService.cpp
new file mode 100644
index 0000000000..48970f3084
--- /dev/null
+++ b/netwerk/protocol/http/EarlyHintsService.cpp
@@ -0,0 +1,184 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=8 et tw=80 : */
+
+/* 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 "EarlyHintsService.h"
+#include "EarlyHintPreconnect.h"
+#include "EarlyHintPreloader.h"
+#include "mozilla/dom/LinkStyle.h"
+#include "mozilla/PreloadHashKey.h"
+#include "mozilla/Telemetry.h"
+#include "mozilla/glean/GleanMetrics.h"
+#include "mozilla/StoragePrincipalHelper.h"
+#include "nsContentUtils.h"
+#include "nsIChannel.h"
+#include "nsICookieJarSettings.h"
+#include "nsILoadInfo.h"
+#include "nsIPrincipal.h"
+#include "nsNetUtil.h"
+#include "nsString.h"
+
+namespace mozilla::net {
+
+EarlyHintsService::EarlyHintsService()
+    : mOngoingEarlyHints(new OngoingEarlyHints()) {}
+
+// implementing the destructor in the .cpp file to allow EarlyHintsService.h
+// not to include EarlyHintPreloader.h, decoupling the two files and hopefully
+// allow faster compile times
+EarlyHintsService::~EarlyHintsService() = default;
+
+void EarlyHintsService::EarlyHint(const nsACString& aLinkHeader,
+                                  nsIURI* aBaseURI, nsIChannel* aChannel,
+                                  const nsACString& aReferrerPolicy,
+                                  const nsACString& aCSPHeader) {
+  mEarlyHintsCount++;
+  if (mFirstEarlyHint.isNothing()) {
+    mFirstEarlyHint.emplace(TimeStamp::NowLoRes());
+  } else {
+    // Only allow one early hint response with link headers. See
+    // https://html.spec.whatwg.org/multipage/semantics.html#early-hints
+    // > Note: Only the first early hint response served during the navigation
+    // > is handled, and it is discarded if it is succeeded by a cross-origin
+    // > redirect.
+    return;
+  }
+
+  nsCOMPtr<nsILoadInfo> loadInfo = aChannel->LoadInfo();
+  // We only follow Early Hints sent on the main document. Make sure that we got
+  // the main document channel here.
+  if (loadInfo->GetExternalContentPolicyType() !=
+      ExtContentPolicy::TYPE_DOCUMENT) {
+    MOZ_ASSERT(false, "Early Hint on non-document channel");
+    return;
+  }
+  nsCOMPtr<nsIPrincipal> principal;
+  // We want to set the top-level document as the triggeringPrincipal for the
+  // load of the sub-resources (image, font, fetch, script, style, fetch and in
+  // the future maybe more). We can't use the `triggeringPrincipal` of the main
+  // document channel, because it is the `systemPrincipal` for user initiated
+  // loads. Same for the `LoadInfo::FindPrincipalToInherit(aChannel)`.
+  //
+  // On 3xx redirects of the main document to cross site locations, all Early
+  // Hint preloads get cancelled as specified in the whatwg spec:
+  //
+  //   Note: Only the first early hint response served during the navigation is
+  //   handled, and it is discarded if it is succeeded by a cross-origin
+  //   redirect. [1]
+  //
+  // Therefore the channel doesn't need to change the principal for any reason
+  // and has the correct principal for the whole lifetime.
+  //
+  // [1]: https://html.spec.whatwg.org/multipage/semantics.html#early-hints
+  nsresult rv = nsContentUtils::GetSecurityManager()->GetChannelResultPrincipal(
+      aChannel, getter_AddRefs(principal));
+  NS_ENSURE_SUCCESS_VOID(rv);
+
+  nsCOMPtr<nsICookieJarSettings> cookieJarSettings;
+  if (NS_FAILED(
+          loadInfo->GetCookieJarSettings(getter_AddRefs(cookieJarSettings)))) {
+    return;
+  }
+
+  // TODO: find out why LinkHeaderParser uses utf16 and check if it can be
+  //       changed to utf8
+  auto linkHeaders = ParseLinkHeader(NS_ConvertUTF8toUTF16(aLinkHeader));
+
+  for (auto& linkHeader : linkHeaders) {
+    CollectLinkTypeTelemetry(linkHeader.mRel);
+    if (linkHeader.mRel.LowerCaseEqualsLiteral("preconnect")) {
+      mLinkType |= dom::LinkStyle::ePRECONNECT;
+      OriginAttributes originAttributes;
+      StoragePrincipalHelper::GetOriginAttributesForNetworkState(
+          aChannel, originAttributes);
+      EarlyHintPreconnect::MaybePreconnect(linkHeader, aBaseURI,
+                                           std::move(originAttributes));
+    } else if (linkHeader.mRel.LowerCaseEqualsLiteral("preload")) {
+      mLinkType |= dom::LinkStyle::ePRELOAD;
+      EarlyHintPreloader::MaybeCreateAndInsertPreload(
+          mOngoingEarlyHints, linkHeader, aBaseURI, principal,
+          cookieJarSettings, aReferrerPolicy, aCSPHeader);
+    }
+  }
+}
+
+void EarlyHintsService::FinalResponse(uint32_t aResponseStatus) {
+  // We will collect telemetry mosly once for a document.
+  // In case of a reddirect this will be called multiple times.
+  CollectTelemetry(Some(aResponseStatus));
+}
+
+void EarlyHintsService::Cancel(const nsACString& aReason) {
+  CollectTelemetry(Nothing());
+  mOngoingEarlyHints->CancelAll(aReason);
+}
+
+void EarlyHintsService::RegisterLinksAndGetConnectArgs(
+    dom::ContentParentId aCpId, nsTArray<EarlyHintConnectArgs>& aOutLinks) {
+  mOngoingEarlyHints->RegisterLinksAndGetConnectArgs(aCpId, aOutLinks);
+}
+
+void EarlyHintsService::CollectTelemetry(Maybe<uint32_t> aResponseStatus) {
+  // EH_NUM_OF_HINTS_PER_PAGE is only collected for the 2xx responses,
+  // regardless of the number of received mEarlyHintsCount.
+  // Other telemetry probes are only collected if there was at least one
+  // EarlyHins response.
+  if (aResponseStatus && (*aResponseStatus <= 299)) {
+    Telemetry::Accumulate(Telemetry::EH_NUM_OF_HINTS_PER_PAGE,
+                          mEarlyHintsCount);
+  }
+  if (mEarlyHintsCount == 0) {
+    return;
+  }
+
+  Telemetry::LABELS_EH_FINAL_RESPONSE label =
+      Telemetry::LABELS_EH_FINAL_RESPONSE::Cancel;
+  if (aResponseStatus) {
+    if (*aResponseStatus <= 299) {
+      label = Telemetry::LABELS_EH_FINAL_RESPONSE::R2xx;
+
+      MOZ_ASSERT(mFirstEarlyHint);
+      Telemetry::AccumulateTimeDelta(Telemetry::EH_TIME_TO_FINAL_RESPONSE,
+                                     *mFirstEarlyHint, TimeStamp::NowLoRes());
+    } else if (*aResponseStatus <= 399) {
+      label = Telemetry::LABELS_EH_FINAL_RESPONSE::R3xx;
+    } else if (*aResponseStatus <= 499) {
+      label = Telemetry::LABELS_EH_FINAL_RESPONSE::R4xx;
+    } else {
+      label = Telemetry::LABELS_EH_FINAL_RESPONSE::Other;
+    }
+  }
+
+  Telemetry::AccumulateCategorical(label);
+
+  // Reset telemetry counters and timestamps.
+  mEarlyHintsCount = 0;
+  mFirstEarlyHint = Nothing();
+}
+
+void EarlyHintsService::CollectLinkTypeTelemetry(const nsAString& aRel) {
+  if (aRel.LowerCaseEqualsLiteral("dns-prefetch")) {
+    glean::netwerk::eh_link_type.Get("dns-prefetch"_ns).Add(1);
+  } else if (aRel.LowerCaseEqualsLiteral("icon")) {
+    glean::netwerk::eh_link_type.Get("icon"_ns).Add(1);
+  } else if (aRel.LowerCaseEqualsLiteral("modulepreload")) {
+    glean::netwerk::eh_link_type.Get("modulepreload"_ns).Add(1);
+  } else if (aRel.LowerCaseEqualsLiteral("preconnect")) {
+    glean::netwerk::eh_link_type.Get("preconnect"_ns).Add(1);
+  } else if (aRel.LowerCaseEqualsLiteral("prefetch")) {
+    glean::netwerk::eh_link_type.Get("prefetch"_ns).Add(1);
+  } else if (aRel.LowerCaseEqualsLiteral("preload")) {
+    glean::netwerk::eh_link_type.Get("preload"_ns).Add(1);
+  } else if (aRel.LowerCaseEqualsLiteral("prerender")) {
+    glean::netwerk::eh_link_type.Get("prerender"_ns).Add(1);
+  } else if (aRel.LowerCaseEqualsLiteral("stylesheet")) {
+    glean::netwerk::eh_link_type.Get("stylesheet"_ns).Add(1);
+  } else {
+    glean::netwerk::eh_link_type.Get("other"_ns).Add(1);
+  }
+}
+
+}  // namespace mozilla::net