Always use recvmmsg or recvmsg if it's available, and consolidate ReadAndDispatchPackets and ReadAn…

net/tools/quic/quic_packet_reader.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/tools/quic/quic_packet_reader.h"
 
 #include <errno.h>
 #ifndef __APPLE__
 // This is a GNU header that is not present in /usr/include on MacOS
 #include <features.h>
@@ skipping 42 matching lines @@
     hdr->msg_iovlen = 1;
 
     hdr->msg_control = packets_[i].cbuf;
     hdr->msg_controllen = kSpaceForOverflowAndIp;
   }
 #endif
 }
 
 QuicPacketReader::~QuicPacketReader() {}
 
-// TODO(danzh): write a public method to wrap ReadAndDispatchPackets() and
-// ReadAndDispatchSinglePacket() based on MMSG_MORE.
 bool QuicPacketReader::ReadAndDispatchPackets(
     int fd,
     int port,
     ProcessPacketInterface* processor,
     QuicPacketCount* packets_dropped) {
 #if MMSG_MORE
+  return ReadAndDispatchManyPackets(fd, port, processor, packets_dropped);
+#else
+  return ReadAndDispatchSinglePacket(fd, port, processor, packets_dropped);
+#endif
+}
+
+bool QuicPacketReader::ReadAndDispatchManyPackets(
+    int fd,
+    int port,
+    ProcessPacketInterface* processor,
+    QuicPacketCount* packets_dropped) {
+#if MMSG_MORE
   // Re-set the length fields in case recvmmsg has changed them.
   for (int i = 0; i < kNumPacketsPerReadMmsgCall; ++i) {
     DCHECK_EQ(kMaxPacketSize, packets_[i].iov.iov_len);
     msghdr* hdr = &mmsg_hdr_[i].msg_hdr;
     hdr->msg_namelen = sizeof(sockaddr_storage);
     DCHECK_EQ(1, hdr->msg_iovlen);
     hdr->msg_controllen = kSpaceForOverflowAndIp;
   }
 
   int packets_read =
@@ skipping 57 matching lines @@
   IPEndPoint server_address(server_ip, port);
   processor->ProcessPacket(server_address, client_address, packet);
 
   // The socket read was successful, so return true even if packet dispatch
   // failed.
   return true;
 }
 
 
 }  // namespace net