Introduce TTL in QuicReceivedPacket.

net/tools/quic/quic_socket_utils.h

Index: net/tools/quic/quic_socket_utils.h
diff --git a/net/tools/quic/quic_socket_utils.h b/net/tools/quic/quic_socket_utils.h
index fd72697fa9c223025f1d323f309cce2457a53a04..f8cc5392c5f81fc8b1aa3868294d1f087c6fc8eb 100644
--- a/net/tools/quic/quic_socket_utils.h
+++ b/net/tools/quic/quic_socket_utils.h
@@ -38,12 +38,13 @@ class QuicSocketUtils {
  public:
   // The first integer is for overflow. The in6_pktinfo is the larger of the
   // address structures present. LinuxTimestamping is present for socket
-  // timestamping.
+  // timestamping.  The subsequent int is for ttl.
   // The final int is a sentinel so the msg_controllen feedback
   // can be used to detect larger control messages than there is space for.
   static const int kSpaceForCmsg =
       CMSG_SPACE(CMSG_LEN(sizeof(int)) + CMSG_LEN(sizeof(in6_pktinfo)) +
                  CMSG_LEN(sizeof(LinuxTimestamping)) +
+                 CMSG_LEN(sizeof(int)) +
                  CMSG_LEN(sizeof(int)));
 
   // Fills in |address| if |hdr| contains IP_PKTINFO or IPV6_PKTINFO. Fills in
@@ -58,6 +59,10 @@ class QuicSocketUtils {
   static bool GetOverflowFromMsghdr(struct msghdr* hdr,
                                     QuicPacketCount* dropped_packets);
 
+  // If the msghdr contains an IP_TTL entry, this will set ttl to the correct
+  // value and return true. Otherwise it will return false.
+  static bool GetTtlFromMsghdr(struct msghdr* hdr, int* ttl);
+
   // Sets either IP_PKTINFO or IPV6_PKTINFO on the socket, based on
   // address_family.  Returns the return code from setsockopt.
   static int SetGetAddressInfo(int fd, int address_family);