Fix crash when trying to connect to an IPv6 IP via a SOCKS4 proxy.

net/dns/host_resolver_impl.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/host_resolver_impl.h"
 
 #if defined(OS_WIN)
 #include <Winsock2.h>
 #elif defined(OS_POSIX)
 #include <netdb.h>
@@ skipping 17 matching lines @@
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/threading/worker_pool.h"
 #include "base/time/time.h"
 #include "base/values.h"
 #include "net/base/address_family.h"
 #include "net/base/address_list.h"
 #include "net/base/dns_reloader.h"
 #include "net/base/dns_util.h"
 #include "net/base/host_port_pair.h"
+#include "net/base/ip_endpoint.h"
 #include "net/base/net_errors.h"
 #include "net/base/net_log.h"
 #include "net/base/net_util.h"
 #include "net/dns/address_sorter.h"
 #include "net/dns/dns_client.h"
 #include "net/dns/dns_config_service.h"
 #include "net/dns/dns_protocol.h"
 #include "net/dns/dns_response.h"
 #include "net/dns/dns_transaction.h"
 #include "net/dns/host_resolver_proc.h"
@@ skipping 127 matching lines @@
           RandIntCallback(),
           net_log.net_log(),
           net_log.source()));
   int rv = socket->Connect(IPEndPoint(dest, 53));
   if (rv != OK)
     return false;
   IPEndPoint endpoint;
   rv = socket->GetLocalAddress(&endpoint);
   if (rv != OK)
     return false;
-  DCHECK(endpoint.GetFamily() == ADDRESS_FAMILY_IPV6);
+  DCHECK_EQ(ADDRESS_FAMILY_IPV6, endpoint.GetFamily());
   const IPAddressNumber& address = endpoint.address();
   bool is_link_local = (address[0] == 0xFE) && ((address[1] & 0xC0) == 0x80);
   if (is_link_local)
     return false;
   const uint8 kTeredoPrefix[] = { 0x20, 0x01, 0, 0 };
   bool is_teredo = std::equal(kTeredoPrefix,
                               kTeredoPrefix + arraysize(kTeredoPrefix),
                               address.begin());
   if (is_teredo)
     return false;
@@ skipping 1829 matching lines @@
   DCHECK(addresses);
   DCHECK(net_error);
   IPAddressNumber ip_number;
   if (!ParseIPLiteralToNumber(key.hostname, &ip_number))
     return false;
 
   DCHECK_EQ(key.host_resolver_flags &
       ~(HOST_RESOLVER_CANONNAME | HOST_RESOLVER_LOOPBACK_ONLY |
         HOST_RESOLVER_DEFAULT_FAMILY_SET_DUE_TO_NO_IPV6),
             0) << " Unhandled flag";
-  bool ipv6_disabled = (default_address_family_ == ADDRESS_FAMILY_IPV4) &&
-      !probe_ipv6_support_;
+
   *net_error = OK;
-  if ((ip_number.size() == kIPv6AddressSize) && ipv6_disabled) {
+  AddressFamily family = GetAddressFamily(ip_number);
+  if (family == ADDRESS_FAMILY_IPV6 &&
+      default_address_family_ == ADDRESS_FAMILY_IPV4 &&

[eroman, 2014/08/05 22:33:41]

As an aside: I am starting to think that "default address family" may not be the
best naming. More like "restrict to address family"

[mmenke, 2014/08/05 22:50:38]

I agree that this would be much clearer.

+      !probe_ipv6_support_) {

[eroman, 2014/08/05 22:33:41]

Can you test for !probe_ipv6_support_ before default_address_family_ ? (Since it
only makes sense in the context where that is false, wouldn't want this to
become an uninitialized memory read in the future).

[mmenke, 2014/08/05 22:50:38]

Done.

+    // Don't return IPv6 addresses if default address family is set to IPv4,
+    // and probes are disabled.
+    *net_error = ERR_NAME_NOT_RESOLVED;
+  } else if (key.address_family != ADDRESS_FAMILY_UNSPECIFIED &&
+             key.address_family != family) {
+    // Don't return IPv6 addresses for IPv4 queries, and vice versa.
     *net_error = ERR_NAME_NOT_RESOLVED;
   } else {
     *addresses = AddressList::CreateFromIPAddress(ip_number, info.port());
     if (key.host_resolver_flags & HOST_RESOLVER_CANONNAME)
       addresses->SetDefaultCanonicalName();
   }
   return true;
 }
 
 bool HostResolverImpl::ServeFromCache(const Key& key,
@@ skipping 301 matching lines @@
     dns_client_->SetConfig(dns_config);
     num_dns_failures_ = 0;
     if (dns_client_->GetConfig())
       UMA_HISTOGRAM_BOOLEAN("AsyncDNS.DnsClientEnabled", true);
   }
 
   AbortDnsTasks();
 }
 
 }  // namespace net