Add a mechanism to disable IPv6.

(1) Adds the ability to specify the address family on a per-request basis.

(2) Exposes a --disable-ipv6 flag to chrome that changes the default address family from AF_UNSPEC to AF_INET (same sort of thing Firefox does).

(3) Changes the backing datastructure for HostCache:EntryMap and HostResolverImpl::JobMap from a "hash_map" to a "std::map". This was for consistency with other code (when I went to add a custom hash trait, I couldn't find any existing code which was using hashmap for custom keys).

(4) Updates about:net-internals to display an address family for the hostcache dump (since it is now a part of the key).

This change is in anticipation of turning off IPv6 host resolving in the PAC utility functions (see bug 24641). But it is also a feature addition.

BUG=24641

TEST=HostCacheTest.AddressFamilyIsPartOfKey
Review URL: http://codereview.chromium.org/302010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@29686 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 14 insertions, 4 deletions

diff --git a/net/base/host_resolver_proc.cc b/net/base/host_resolver_proc.cc
index 8951646..af92087 100644
--- a/net/base/host_resolver_proc.cc
+++ b/net/base/host_resolver_proc.cc
@@ -52,12 +52,13 @@ HostResolverProc* HostResolverProc::GetDefault() {
 }
 
 int HostResolverProc::ResolveUsingPrevious(const std::string& host,
+                                           AddressFamily address_family,
                                            AddressList* addrlist) {
   if (previous_proc_)
-    return previous_proc_->Resolve(host, addrlist);
+    return previous_proc_->Resolve(host, address_family, addrlist);
 
   // Final fallback is the system resolver.
-  return SystemHostResolverProc(host, addrlist);
+  return SystemHostResolverProc(host, address_family, addrlist);
 }
 
 #if defined(OS_LINUX)
@@ -124,7 +125,9 @@ ThreadLocalStorage::Slot DnsReloadTimer::tls_index_(base::LINKER_INITIALIZED);
 
 #endif  // defined(OS_LINUX)
 
-int SystemHostResolverProc(const std::string& host, AddressList* addrlist) {
+int SystemHostResolverProc(const std::string& host,
+                           AddressFamily address_family,
+                           AddressList* addrlist) {
   // The result of |getaddrinfo| for empty hosts is inconsistent across systems.
   // On Windows it gives the default interface's address, whereas on Linux it
   // gives an error. We will make it fail on all platforms for consistency.
@@ -133,7 +136,14 @@ int SystemHostResolverProc(const std::string& host, AddressList* addrlist) {
 
   struct addrinfo* ai = NULL;
   struct addrinfo hints = {0};
-  hints.ai_family = AF_UNSPEC;
+
+  switch (address_family) {
+    case ADDRESS_FAMILY_IPV4_ONLY:
+      hints.ai_family = AF_INET;
+      break;
+    default:
+      hints.ai_family = AF_UNSPEC;
+  }
 
 #if defined(OS_WIN)
   // DO NOT USE AI_ADDRCONFIG ON WINDOWS.