Bug 1866218 - Use the latest version of HTTP/3 from Alt-Svc headers, r=necko-reviewers,valentin

Make Firefox use the latest HTTP/3 version listed in Alt-Svc headers, rather than the first one.

Differential Revision: https://phabricator.services.mozilla.com/D203235

netwerk/protocol/http/AlternateServices.cpp

@@ -7,6 +7,7 @@
 #include "HttpLog.h"
 
 #include "AlternateServices.h"
+#include <algorithm>
 #include "LoadInfo.h"
 #include "mozilla/Atomics.h"
 #include "mozilla/StaticPrefs_network.h"
@@ -87,16 +88,15 @@ void AltSvcMapping::ProcessHeader(
   ParsedHeaderValueListList parsedAltSvc(buf);
   int32_t numEntriesInHeader = parsedAltSvc.mValues.Length();
 
-  // Only use one http3 version.
-  bool http3Found = false;
-
+  nsTArray<RefPtr<AltSvcMapping>> h3Mappings;
+  nsTArray<RefPtr<AltSvcMapping>> otherMappings;
   for (uint32_t index = 0; index < parsedAltSvc.mValues.Length(); ++index) {
     uint32_t maxage = 86400;  // default
     nsAutoCString hostname;
     nsAutoCString npnToken;
     int32_t portno = originPort;
     bool clearEntry = false;
-    bool isHttp3 = false;
+    SupportedAlpnRank alpnRank = SupportedAlpnRank::NOT_SUPPORTED;
 
     for (uint32_t pairIndex = 0;
          pairIndex < parsedAltSvc.mValues[index].mValues.Length();
@@ -116,7 +116,7 @@ void AltSvcMapping::ProcessHeader(
 
         // h2=[hostname]:443 or h3-xx=[hostname]:port
         // XX is current version we support and it is define in nsHttp.h.
-        isHttp3 = gHttpHandler->IsHttp3VersionSupported(currentName);
+        alpnRank = IsAlpnSupported(currentName);
         npnToken = currentName;
 
         int32_t colonIndex = currentValue.FindChar(':');
@@ -153,12 +153,7 @@ void AltSvcMapping::ProcessHeader(
     // update nsCString length
     nsUnescape(npnToken.BeginWriting());
     npnToken.SetLength(strlen(npnToken.BeginReading()));
-
-    if (http3Found && isHttp3) {
-      LOG(("Alt Svc ignore multiple Http3 options (%s)", npnToken.get()));
-      continue;
-    }
-
+    bool isHttp3 = net::IsHttp3(alpnRank);
     SpdyInformation* spdyInfo = gHttpHandler->SpdyInfo();
     if (!(npnToken.Equals(spdyInfo->VersionString) &&
           StaticPrefs::network_http_http2_enabled()) &&
@@ -169,16 +164,13 @@ void AltSvcMapping::ProcessHeader(
       continue;
     }
 
-    if (isHttp3) {
-      http3Found = true;
-    }
-
-    RefPtr<AltSvcMapping> mapping =
-        new AltSvcMapping(gHttpHandler->AltServiceCache()->GetStoragePtr(),
-                          gHttpHandler->AltServiceCache()->StorageEpoch(),
-                          originScheme, originHost, originPort, username,
-                          privateBrowsing, NowInSeconds() + maxage, hostname,
-                          portno, npnToken, originAttributes, isHttp3);
+    LOG(("AltSvcMapping created npnToken=%s", npnToken.get()));
+    RefPtr<AltSvcMapping> mapping = new AltSvcMapping(
+        gHttpHandler->AltServiceCache()->GetStoragePtr(),
+        gHttpHandler->AltServiceCache()->StorageEpoch(), originScheme,
+        originHost, originPort, username, privateBrowsing,
+        NowInSeconds() + maxage, hostname, portno, npnToken, originAttributes,
+        isHttp3, alpnRank);
     if (mapping->TTL() <= 0) {
       LOG(("Alt Svc invalid map"));
       mapping = nullptr;
@@ -186,15 +178,39 @@ void AltSvcMapping::ProcessHeader(
       // as that would have happened if we had accepted the parameters.
       gHttpHandler->AltServiceCache()->ClearHostMapping(originHost, originPort,
                                                         originAttributes);
-    } else if (!aDontValidate) {
-      gHttpHandler->UpdateAltServiceMapping(mapping, proxyInfo, callbacks, caps,
-                                            originAttributes);
     } else {
-      gHttpHandler->UpdateAltServiceMappingWithoutValidation(
-          mapping, proxyInfo, callbacks, caps, originAttributes);
+      if (isHttp3) {
+        h3Mappings.AppendElement(std::move(mapping));
+      } else {
+        otherMappings.AppendElement(std::move(mapping));
+      }
     }
   }
 
+  auto doUpdateAltSvcMapping = [&](AltSvcMapping* aMapping) {
+    if (!aDontValidate) {
+      gHttpHandler->UpdateAltServiceMapping(aMapping, proxyInfo, callbacks,
+                                            caps, originAttributes);
+    } else {
+      gHttpHandler->UpdateAltServiceMappingWithoutValidation(
+          aMapping, proxyInfo, callbacks, caps, originAttributes);
+    }
+  };
+
+  if (!h3Mappings.IsEmpty()) {
+    // Select the HTTP/3 (h3) AltSvcMapping with the highest ALPN rank from
+    // h3Mappings.
+    RefPtr<AltSvcMapping> latestH3Mapping = *std::max_element(
+        h3Mappings.begin(), h3Mappings.end(),
+        [](const RefPtr<AltSvcMapping>& a, const RefPtr<AltSvcMapping>& b) {
+          return a->AlpnRank() < b->AlpnRank();
+        });
+    doUpdateAltSvcMapping(latestH3Mapping);
+  }
+
+  std::for_each(otherMappings.begin(), otherMappings.end(),
+                doUpdateAltSvcMapping);
+
   if (numEntriesInHeader) {  // Ignore headers that were just "alt-svc: clear"
     Telemetry::Accumulate(Telemetry::HTTP_ALTSVC_ENTRIES_PER_HEADER,
                           numEntriesInHeader);
@@ -209,7 +225,7 @@ AltSvcMapping::AltSvcMapping(nsIDataStorage* storage, int32_t epoch,
                              const nsACString& alternateHost,
                              int32_t alternatePort, const nsACString& npnToken,
                              const OriginAttributes& originAttributes,
-                             bool aIsHttp3)
+                             bool aIsHttp3, SupportedAlpnRank aRank)
     : mStorage(storage),
       mStorageEpoch(epoch),
       mAlternateHost(alternateHost),
@@ -221,7 +237,8 @@ AltSvcMapping::AltSvcMapping(nsIDataStorage* storage, int32_t epoch,
       mExpiresAt(expiresAt),
       mNPNToken(npnToken),
       mOriginAttributes(originAttributes),
-      mIsHttp3(aIsHttp3) {
+      mIsHttp3(aIsHttp3),
+      mAlpnRank(aRank) {
   MOZ_ASSERT(NS_IsMainThread());
 
   if (NS_FAILED(SchemeIsHTTPS(originScheme, mHttps))) {

netwerk/protocol/http/AlternateServices.h

@@ -23,6 +23,7 @@ https://tools.ietf.org/html/draft-ietf-httpbis-alt-svc-06
 #ifndef mozilla_net_AlternateServices_h
 #define mozilla_net_AlternateServices_h
 
+#include "nsHttp.h"
 #include "nsRefPtrHashtable.h"
 #include "nsString.h"
 #include "nsIDataStorage.h"
@@ -53,7 +54,8 @@ class AltSvcMapping {
                 bool privateBrowsing, uint32_t expiresAt,
                 const nsACString& alternateHost, int32_t alternatePort,
                 const nsACString& npnToken,
-                const OriginAttributes& originAttributes, bool aIsHttp3);
+                const OriginAttributes& originAttributes, bool aIsHttp3,
+                SupportedAlpnRank aRank);
 
  public:
   AltSvcMapping(nsIDataStorage* storage, int32_t storageEpoch,
@@ -103,6 +105,7 @@ class AltSvcMapping {
 
   bool IsHttp3() { return mIsHttp3; }
   const nsCString& NPNToken() const { return mNPNToken; }
+  SupportedAlpnRank AlpnRank() const { return mAlpnRank; }
 
  private:
   virtual ~AltSvcMapping() = default;
@@ -138,6 +141,7 @@ class AltSvcMapping {
 
   bool mSyncOnlyOnSuccess{false};
   bool mIsHttp3{false};
+  SupportedAlpnRank mAlpnRank{SupportedAlpnRank::NOT_SUPPORTED};
 };
 
 class AltSvcOverride : public nsIInterfaceRequestor,

netwerk/test/unit/test_http3_alt_svc.js

@@ -5,7 +5,7 @@ let h3AltSvc;
 let h3Route;
 let prefs;
 
-let tests = [test_https_alt_svc, testsDone];
+let tests = [test_https_alt_svc, test_https_alt_svc_1, testsDone];
 
 let current_test = 0;
 
@@ -68,7 +68,9 @@ function makeChan(uri) {
   return chan;
 }
 
-let WaitForHttp3Listener = function () {};
+let WaitForHttp3Listener = function (expectedH3Version) {
+  this._expectedH3Version = expectedH3Version;
+};
 
 WaitForHttp3Listener.prototype = {
   onDataAvailableFired: false,
@@ -96,13 +98,18 @@ WaitForHttp3Listener.prototype = {
       try {
         httpVersion = request.protocolVersion;
       } catch (e) {}
-      Assert.equal(httpVersion, "h3-29");
+      Assert.equal(httpVersion, this._expectedH3Version);
       run_next_test();
     } else {
       dump("poll later for alt svc mapping\n");
       do_test_pending();
       do_timeout(500, () => {
-        doTest(this.uri, this.expectedRoute, this.h3AltSvc);
+        doTest(
+          this.uri,
+          this.expectedRoute,
+          this.h3AltSvc,
+          this._expectedH3Version
+        );
       });
     }
 
@@ -110,9 +117,9 @@ WaitForHttp3Listener.prototype = {
   },
 };
 
-function doTest(uri, expectedRoute, altSvc) {
+function doTest(uri, expectedRoute, altSvc, expectedH3Version) {
   let chan = makeChan(uri);
-  let listener = new WaitForHttp3Listener();
+  let listener = new WaitForHttp3Listener(expectedH3Version);
   listener.uri = uri;
   listener.expectedRoute = expectedRoute;
   listener.h3AltSvc = altSvc;
@@ -121,11 +128,23 @@ function doTest(uri, expectedRoute, altSvc) {
 }
 
 // Test Alt-Svc for http3.
-// H2 server returns alt-svc=h2=foo2.example.com:8000,h3-29=:h3port,h3-30=foo2.example.com:8443
+// H2 server returns alt-svc=h2=foo2.example.com:8000,h3-29=:h3port
 function test_https_alt_svc() {
   dump("test_https_alt_svc()\n");
   do_test_pending();
-  doTest(httpsOrigin + "http3-test2", h3Route, h3AltSvc);
+  doTest(httpsOrigin + "http3-test2", h3Route, h3AltSvc, "h3-29");
+}
+
+// Test if we use the latest version of HTTP/3.
+// H2 server returns alt-svc=h3-29=:h3port,h3=:h3port
+function test_https_alt_svc_1() {
+  // Close the previous connection and clear alt-svc mappings.
+  Services.obs.notifyObservers(null, "last-pb-context-exited");
+  Services.obs.notifyObservers(null, "net:cancel-all-connections");
+  do_test_pending();
+  do_timeout(1000, () => {
+    doTest(httpsOrigin + "http3-test3", h3Route, h3AltSvc, "h3");
+  });
 }
 
 function testsDone() {

testing/xpcshell/moz-http2/moz-http2.js

@@ -879,9 +879,13 @@ function handleRequest(req, res) {
     res.setHeader("Cache-Control", "no-cache");
     res.setHeader(
       "Alt-Svc",
-      "h2=foo2.example.com:8000,h3-29=" +
-        req.headers["x-altsvc"] +
-        ",h3-30=foo2.example.com:8443"
+      "h2=foo2.example.com:8000,h3-29=" + req.headers["x-altsvc"]
+    );
+  } else if (u.pathname === "/http3-test3") {
+    res.setHeader("Cache-Control", "no-cache");
+    res.setHeader(
+      "Alt-Svc",
+      "h3-29=" + req.headers["x-altsvc"] + ",h3=" + req.headers["x-altsvc"]
     );
   }
   // for use with test_trr.js