[net/dns] Resolve AF_UNSPEC on dual-stacked systems. Sort addresses according to RFC3484.

net/dns/address_sorter_win.cc

+// Copyright (c) 2012 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/dns/address_sorter.h"
+
+#include <winsock2.h>
+
+#include <algorithm>
+
+#include "base/bind.h"
+#include "base/location.h"
+#include "base/logging.h"
+#include "base/threading/worker_pool.h"
+#include "base/win/windows_version.h"
+#include "net/base/address_list.h"
+#include "net/base/ip_endpoint.h"
+#include "net/base/winsock_init.h"
+
+namespace net {
+
+namespace {
+
+class AddressSorterWin : public AddressSorter {
+ public:
+  AddressSorterWin() {
+    EnsureWinsockInit();
+  }
+
+  virtual ~AddressSorterWin() {}
+
+  // AddressSorter:
+  virtual void Sort(const AddressList& list,
+                    const CallbackType& callback) const OVERRIDE {
+    DCHECK(!list.empty());
+    scoped_refptr<Job> job = new Job(list, callback);
+  }
+
+ private:
+  // Executes the SIO_ADDRESS_LIST_SORT ioctl on the WorkerPool, and
+  // performs the necessary conversions to/from AddressList.
+  class Job : public base::RefCountedThreadSafe<Job> {
+   public:
+    Job(const AddressList& list, const CallbackType& callback)
+        : callback_(callback),
+          buffer_size_(sizeof(SOCKET_ADDRESS_LIST) +
+                       list.size() * (sizeof(SOCKET_ADDRESS) +
+                                      sizeof(SOCKADDR_STORAGE))),
+          input_buffer_(reinterpret_cast<SOCKET_ADDRESS_LIST*>(
+              malloc(buffer_size_))),
+          output_buffer_(reinterpret_cast<SOCKET_ADDRESS_LIST*>(
+              malloc(buffer_size_))),
+          success_(false) {
+      input_buffer_->iAddressCount = list.size();
+      SOCKADDR_STORAGE* storage = reinterpret_cast<SOCKADDR_STORAGE*>(
+          input_buffer_->Address + input_buffer_->iAddressCount);
+
+      for (size_t i = 0; i < list.size(); ++i) {
+        IPEndPoint ipe = list[i];
+        // Addresses must be sockaddr_in6.
+        if (ipe.GetFamily() == AF_INET) {
+          ipe = IPEndPoint(ConvertIPv4NumberToIPv6Number(ipe.address()),
+                           ipe.port());
+        }
+
+        struct sockaddr* addr = reinterpret_cast<struct sockaddr*>(storage + i);
+        socklen_t addr_len = sizeof(SOCKADDR_STORAGE);
+        bool result = ipe.ToSockAddr(addr, &addr_len);
+        DCHECK(result);
+        input_buffer_->Address[i].lpSockaddr = addr;
+        input_buffer_->Address[i].iSockaddrLength = addr_len;
+      }
+
+      if (!base::WorkerPool::PostTaskAndReply(
+          FROM_HERE,
+          base::Bind(&Job::Run, this),
+          base::Bind(&Job::OnComplete, this),
+          false /* task is slow */)) {
+        LOG(ERROR) << "WorkerPool::PostTaskAndReply failed";
+        OnComplete();
+      }
+    }
+
+   private:
+    friend class base::RefCountedThreadSafe<Job>;
+    ~Job() {}
+
+    // Executed on the WorkerPool.
+    void Run() {
+      SOCKET sock = socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP);
+      DCHECK_NE(INVALID_SOCKET, sock);

[szym, 2012/08/15 17:16:48]

This could fail on systems without ipv6 stack (for example, Windows XP without
Teredo). However, in that case we'd expect to disable IPv6 via
TestIPv6Support().

The lenient solution is to simply quit here. The strict solution is to leave the
DCHECK. In both cases we need to disable the test if |socket(AF_INET6, ...) ==
INVALID_SOCKET|

[mmenke1, 2012/08/15 17:36:53]

May want to delete all the IPv6 addresses in this case, at least if we have IPv4
addresses as well.  No need to address that in this CL.

Couldn't we have the unit test check for graceful failure in this case - would
still need to detect the case, but instead of aborting, could check that
success_ = false.

+      DWORD result_size = 0;
+      int result = WSAIoctl(sock, SIO_ADDRESS_LIST_SORT, input_buffer_.get(),
+                            buffer_size_, output_buffer_.get(), buffer_size_,
+                            &result_size, NULL, NULL);
+      if (result == SOCKET_ERROR) {
+        LOG(ERROR) << "SIO_ADDRESS_LIST_SORT failed " << WSAGetLastError();
+      } else {
+        success_ = true;
+      }
+      closesocket(sock);
+    }
+
+    // Executed on the calling thread.
+    void OnComplete() {
+      AddressList list;
+      if (success_) {
+        list.reserve(output_buffer_->iAddressCount);
+        for (int i = 0; i < output_buffer_->iAddressCount; ++i) {
+          IPEndPoint ipe;
+          ipe.FromSockAddr(output_buffer_->Address[i].lpSockaddr,
+                           output_buffer_->Address[i].iSockaddrLength);
+          // Unmap V4MAPPED IPv6 addresses so that Happy Eyeballs works.
+          if (IsIPv4Mapped(ipe.address())) {
+            ipe = IPEndPoint(ConvertIPv4MappedToIPv4(ipe.address()),
+                                                     ipe.port());
+          }
+          list.push_back(ipe);
+        }
+      }
+      callback_.Run(success_, list);
+    }
+
+    const CallbackType callback_;
+    const size_t buffer_size_;
+    scoped_ptr_malloc<SOCKET_ADDRESS_LIST> input_buffer_;
+    scoped_ptr_malloc<SOCKET_ADDRESS_LIST> output_buffer_;
+    bool success_;
+
+    DISALLOW_COPY_AND_ASSIGN(Job);
+  };
+
+  DISALLOW_COPY_AND_ASSIGN(AddressSorterWin);
+};
+
+// Merges |list_ipv4| and |list_ipv6| before passing it to |callback|, but
+// only if |success| is true.
+void MergeResults(const AddressSorter::CallbackType& callback,
+                  const AddressList& list_ipv4,
+                  bool success,
+                  const AddressList& list_ipv6) {
+  if (!success) {
+    callback.Run(false, AddressList());
+    return;
+  }
+  AddressList list;
+  list.insert(list.end(), list_ipv6.begin(), list_ipv6.end());
+  list.insert(list.end(), list_ipv4.begin(), list_ipv4.end());
+  callback.Run(true, list);
+}
+
+// Wrapper for AddressSorterWin which does not sort IPv4 or IPv4-mapped
+// addresses but always puts them at the end of the list. Needed because the
+// SIO_ADDRESS_LIST_SORT does not support IPv4 addresses on Windows XP.
+class AddressSorterWinXP : public AddressSorter {
+ public:
+  AddressSorterWinXP() {}
+  virtual ~AddressSorterWinXP() {}
+
+  // AddressSorter:
+  virtual void Sort(const AddressList& list,
+                    const CallbackType& callback) const OVERRIDE {
+    AddressList list_ipv4;
+    AddressList list_ipv6;
+    for (size_t i = 0; i < list.size(); ++i) {
+      const IPEndPoint& ipe = list[i];
+      if (ipe.GetFamily() == AF_INET) {
+        list_ipv4.push_back(ipe);
+      } else {
+        list_ipv6.push_back(ipe);
+      }
+    }
+    if (!list_ipv6.empty()) {
+      sorter_.Sort(list_ipv6, base::Bind(&MergeResults, callback, list_ipv4));
+    } else {
+      NOTREACHED() << "Should not be called with IPv4-only addresses.";
+      callback.Run(true, list);
+    }
+  }
+
+ private:
+  AddressSorterWin sorter_;
+
+  DISALLOW_COPY_AND_ASSIGN(AddressSorterWinXP);
+};
+
+}  // namespace
+
+// static
+scoped_ptr<AddressSorter> AddressSorter::CreateAddressSorter() {
+  if (base::win::GetVersion() < base::win::VERSION_VISTA)
+    return scoped_ptr<AddressSorter>(new AddressSorterWinXP());
+  return scoped_ptr<AddressSorter>(new AddressSorterWin());
+}
+
+}  // namespace net
+