Avoid heap allocations in IPAddress

net/quic/platform/impl/quic_ip_address_impl.cc

 // Copyright (c) 2016 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/quic/platform/impl/quic_ip_address_impl.h"
 
+#include "base/containers/stack_container.h"
 #include "net/base/address_family.h"
 #include "net/quic/platform/api/quic_bug_tracker.h"
 
 #if defined(OS_WIN)
 #include <winsock2.h>
 #include <ws2bth.h>
 #elif defined(OS_POSIX)
 #include <netinet/in.h>
 #endif
 
@@ skipping 83 matching lines @@
   }
   return QuicIpAddressImpl(ip_address_);
 }
 
 bool QuicIpAddressImpl::FromPackedString(const char* data, size_t length) {
   if (length != IPAddress::kIPv4AddressSize &&
       length != IPAddress::kIPv6AddressSize) {
     QUIC_BUG << "Invalid packed IP address of length " << length;
     return false;
   }
-  std::vector<uint8_t> ip(length);
+  base::StackVector<uint8_t, 16> ip;
+  ip->resize(length);
   memcpy(&ip[0], data, length);
-  ip_address_ = IPAddress(ip);
+  ip_address_ = IPAddress(ip->data(), ip->size());

[eroman, 2017/05/19 22:00:07]

Delete the three lines above, and change this one to:

ip_address_ = IPAddress(data, length);

(Doesn't seem like the memcpy is necessary).

[Ryan Hamilton, 2017/05/20 03:21:44]

Done. (needs a reinterpret_cast though. Thanks, C++)

   return true;
 }
 
 bool QuicIpAddressImpl::FromString(string str) {
   return ip_address_.AssignFromIPLiteral(str);
 }
 
 bool QuicIpAddressImpl::IsIPv4() const {
   return ip_address_.IsIPv4();
 }
 
 bool QuicIpAddressImpl::IsIPv6() const {
   return ip_address_.IsIPv6();
 }
 
 bool QuicIpAddressImpl::InSameSubnet(const QuicIpAddressImpl& other,
                                      int subnet_length) {
   return IPAddressMatchesPrefix(ip_address_, other.ip_address(), subnet_length);
 }
 
 }  // namespace net