Drop Packets with the multipath bit set before decryption. Protected by FLAGS_quic_reloadable_flag_…

net/quic/core/quic_framer.cc

Index: net/quic/core/quic_framer.cc
diff --git a/net/quic/core/quic_framer.cc b/net/quic/core/quic_framer.cc
index 977fc2f925257a33c173b3332834b980a54a36b2..68a0fb8394a53063532c7a65903a2bb08f5404a2 100644
--- a/net/quic/core/quic_framer.cc
+++ b/net/quic/core/quic_framer.cc
@@ -784,7 +784,9 @@ bool QuicFramer::ProcessPublicHeader(QuicDataReader* reader,
       (public_flags & PACKET_PUBLIC_FLAGS_VERSION) != 0;
 
   if (validate_flags_ && !public_header->version_flag &&
-      public_flags > PACKET_PUBLIC_FLAGS_MAX) {
+      public_flags > (FLAGS_quic_reloadable_flag_quic_remove_multipath_bit
+                          ? PACKET_PUBLIC_FLAGS_MAX_WITHOUT_MULTIPATH_FLAG
+                          : PACKET_PUBLIC_FLAGS_MAX)) {
     set_detailed_error("Illegal public flags value.");
     return false;
   }
@@ -825,7 +827,10 @@ bool QuicFramer::ProcessPublicHeader(QuicDataReader* reader,
     // If not, this raises an error.
     last_version_tag_ = version_tag;
     QuicVersion version = QuicTagToQuicVersion(version_tag);
-    if (version == quic_version_ && public_flags > PACKET_PUBLIC_FLAGS_MAX) {
+    if (version == quic_version_ &&
+        public_flags > (FLAGS_quic_reloadable_flag_quic_remove_multipath_bit
+                            ? PACKET_PUBLIC_FLAGS_MAX_WITHOUT_MULTIPATH_FLAG
+                            : PACKET_PUBLIC_FLAGS_MAX)) {
       set_detailed_error("Illegal public flags value.");
       return false;
     }