Add client connection ID methods to quic_packets

gfe-relnote: n/a, adds new currently unused methods
PiperOrigin-RevId: 250704882
Change-Id: I0205e7638c229df39c1bb60661433c34adec5f84

quic/core/quic_packets.cc

diff --git a/quic/core/quic_packets.cc b/quic/core/quic_packets.cc
index 57bda54..738cc6e 100644
--- a/quic/core/quic_packets.cc
+++ b/quic/core/quic_packets.cc
@@ -27,6 +27,16 @@
   return header.source_connection_id;
 }
 
+QuicConnectionId GetClientConnectionIdAsRecipient(
+    const QuicPacketHeader& header,
+    Perspective perspective) {
+  DCHECK(GetQuicRestartFlag(quic_do_not_override_connection_id));
+  if (perspective == Perspective::IS_CLIENT) {
+    return header.destination_connection_id;
+  }
+  return header.source_connection_id;
+}
+
 QuicConnectionId GetServerConnectionIdAsSender(const QuicPacketHeader& header,
                                                Perspective perspective) {
   if (perspective == Perspective::IS_CLIENT ||
@@ -48,6 +58,16 @@
   return header.source_connection_id_included;
 }
 
+QuicConnectionId GetClientConnectionIdAsSender(const QuicPacketHeader& header,
+                                               Perspective perspective) {
+  if (perspective == Perspective::IS_CLIENT ||
+      !GetQuicRestartFlag(quic_do_not_override_connection_id)) {
+    return header.source_connection_id;
+  }
+  QUIC_RESTART_FLAG_COUNT_N(quic_do_not_override_connection_id, 3, 5);
+  return header.destination_connection_id;
+}
+
 QuicConnectionIdIncluded GetClientConnectionIdIncludedAsSender(
     const QuicPacketHeader& header,
     Perspective perspective) {