Isolates generic DnsClient from AsyncHostResolver.

net/dns/dns_session.cc

Index: net/dns/dns_session.cc
diff --git a/net/dns/dns_session.cc b/net/dns/dns_session.cc
new file mode 100644
index 0000000000000000000000000000000000000000..15cbaa209a4eb81752df970af11dd31c60cda27c
--- /dev/null
+++ b/net/dns/dns_session.cc
@@ -0,0 +1,47 @@
+// Copyright (c) 2011 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/dns_session.h"
+
+#include "base/basictypes.h"
+#include "base/bind.h"
+#include "base/time.h"
+#include "net/base/ip_endpoint.h"
+#include "net/dns/dns_config_service.h"
+#include "net/socket/client_socket_factory.h"
+
+namespace net {
+
+DnsSession::DnsSession(const DnsConfig& config,
+                       ClientSocketFactory* factory,
+                       const RandIntCallback& rand_int_callback,
+                       NetLog* net_log)
+    : config_(config),
+      socket_factory_(factory),
+      rand_callback_(base::Bind(rand_int_callback, 0, kuint16max)),
+      net_log_(net_log),
+      server_index_(0) {
+}
+
+int DnsSession::NextId() const {
+  return rand_callback_.Run();
+}
+
+const IPEndPoint& DnsSession::NextServer() {
+  // TODO(szym): Rotate servers on failures.
+  const IPEndPoint& ipe = config_.nameservers[server_index_];
+  if (config_.rotate)
+    server_index_ = (server_index_ + 1) % config_.nameservers.size();
+  return ipe;
+}
+
+base::TimeDelta DnsSession::NextTimeout(int attempt) {
+  // TODO(szym): Adapt timeout to observed RTT.
+  return config_.timeout * (attempt + 1);
+}
+
+DnsSession::~DnsSession() {}
+
+}  // namespace net
+