net: move host_resolver files from net/base to net/dns

net/base/host_resolver.h

-// 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.
-
-#ifndef NET_BASE_HOST_RESOLVER_H_
-#define NET_BASE_HOST_RESOLVER_H_
-
-#include <string>
-
-#include "base/memory/scoped_ptr.h"
-#include "net/base/address_family.h"
-#include "net/base/completion_callback.h"
-#include "net/base/host_port_pair.h"
-#include "net/base/net_export.h"
-#include "net/base/net_util.h"
-#include "net/base/request_priority.h"
-
-namespace base {
-class Value;
-}
-
-namespace net {
-
-class AddressList;
-class BoundNetLog;
-class HostCache;
-class HostResolverProc;
-class NetLog;
-
-// This class represents the task of resolving hostnames (or IP address
-// literal) to an AddressList object.
-//
-// HostResolver can handle multiple requests at a time, so when cancelling a
-// request the RequestHandle that was returned by Resolve() needs to be
-// given.  A simpler alternative for consumers that only have 1 outstanding
-// request at a time is to create a SingleRequestHostResolver wrapper around
-// HostResolver (which will automatically cancel the single request when it
-// goes out of scope).
-class NET_EXPORT HostResolver {
- public:
-  // |max_concurrent_resolves| is how many resolve requests will be allowed to
-  // run in parallel. Pass HostResolver::kDefaultParallelism to choose a
-  // default value.
-  // |max_retry_attempts| is the maximum number of times we will retry for host
-  // resolution. Pass HostResolver::kDefaultRetryAttempts to choose a default
-  // value.
-  // |enable_caching| controls whether a HostCache is used.
-  struct NET_EXPORT Options {
-    Options();
-
-    size_t max_concurrent_resolves;
-    size_t max_retry_attempts;
-    bool enable_caching;
-  };
-
-  // The parameters for doing a Resolve(). A hostname and port are required,
-  // the rest are optional (and have reasonable defaults).
-  class NET_EXPORT RequestInfo {
-   public:
-    explicit RequestInfo(const HostPortPair& host_port_pair);
-
-    const HostPortPair& host_port_pair() const { return host_port_pair_; }
-    void set_host_port_pair(const HostPortPair& host_port_pair) {
-      host_port_pair_ = host_port_pair;
-    }
-
-    int port() const { return host_port_pair_.port(); }
-    const std::string& hostname() const { return host_port_pair_.host(); }
-
-    AddressFamily address_family() const { return address_family_; }
-    void set_address_family(AddressFamily address_family) {
-      address_family_ = address_family;
-    }
-
-    HostResolverFlags host_resolver_flags() const {
-      return host_resolver_flags_;
-    }
-    void set_host_resolver_flags(HostResolverFlags host_resolver_flags) {
-      host_resolver_flags_ = host_resolver_flags;
-    }
-
-    bool allow_cached_response() const { return allow_cached_response_; }
-    void set_allow_cached_response(bool b) { allow_cached_response_ = b; }
-
-    bool is_speculative() const { return is_speculative_; }
-    void set_is_speculative(bool b) { is_speculative_ = b; }
-
-    RequestPriority priority() const { return priority_; }
-    void set_priority(RequestPriority priority) { priority_ = priority; }
-
-   private:
-    // The hostname to resolve, and the port to use in resulting sockaddrs.
-    HostPortPair host_port_pair_;
-
-    // The address family to restrict results to.
-    AddressFamily address_family_;
-
-    // Flags to use when resolving this request.
-    HostResolverFlags host_resolver_flags_;
-
-    // Whether it is ok to return a result from the host cache.
-    bool allow_cached_response_;
-
-    // Whether this request was started by the DNS prefetcher.
-    bool is_speculative_;
-
-    // The priority for the request.
-    RequestPriority priority_;
-  };
-
-  // Opaque type used to cancel a request.
-  typedef void* RequestHandle;
-
-  // This value can be passed into CreateSystemResolver as the
-  // |max_concurrent_resolves| parameter. It will select a default level of
-  // concurrency.
-  static const size_t kDefaultParallelism = 0;
-
-  // This value can be passed into CreateSystemResolver as the
-  // |max_retry_attempts| parameter.
-  static const size_t kDefaultRetryAttempts = -1;
-
-  // If any completion callbacks are pending when the resolver is destroyed,
-  // the host resolutions are cancelled, and the completion callbacks will not
-  // be called.
-  virtual ~HostResolver();
-
-  // Resolves the given hostname (or IP address literal), filling out the
-  // |addresses| object upon success.  The |info.port| parameter will be set as
-  // the sin(6)_port field of the sockaddr_in{6} struct.  Returns OK if
-  // successful or an error code upon failure.  Returns
-  // ERR_NAME_NOT_RESOLVED if hostname is invalid, or if it is an
-  // incompatible IP literal (e.g. IPv6 is disabled and it is an IPv6
-  // literal).
-  //
-  // If the operation cannot be completed synchronously, ERR_IO_PENDING will
-  // be returned and the real result code will be passed to the completion
-  // callback.  Otherwise the result code is returned immediately from this
-  // call.
-  //
-  // If |out_req| is non-NULL, then |*out_req| will be filled with a handle to
-  // the async request. This handle is not valid after the request has
-  // completed.
-  //
-  // Profiling information for the request is saved to |net_log| if non-NULL.
-  virtual int Resolve(const RequestInfo& info,
-                      AddressList* addresses,
-                      const CompletionCallback& callback,
-                      RequestHandle* out_req,
-                      const BoundNetLog& net_log) = 0;
-
-  // Resolves the given hostname (or IP address literal) out of cache or HOSTS
-  // file (if enabled) only. This is guaranteed to complete synchronously.
-  // This acts like |Resolve()| if the hostname is IP literal, or cached value
-  // or HOSTS entry exists. Otherwise, ERR_DNS_CACHE_MISS is returned.
-  virtual int ResolveFromCache(const RequestInfo& info,
-                               AddressList* addresses,
-                               const BoundNetLog& net_log) = 0;
-
-  // Cancels the specified request. |req| is the handle returned by Resolve().
-  // After a request is canceled, its completion callback will not be called.
-  // CancelRequest must NOT be called after the request's completion callback
-  // has already run or the request was canceled.
-  virtual void CancelRequest(RequestHandle req) = 0;
-
-  // Sets the default AddressFamily to use when requests have left it
-  // unspecified. For example, this could be used to restrict resolution
-  // results to AF_INET by passing in ADDRESS_FAMILY_IPV4, or to
-  // AF_INET6 by passing in ADDRESS_FAMILY_IPV6.
-  virtual void SetDefaultAddressFamily(AddressFamily address_family) {}
-  virtual AddressFamily GetDefaultAddressFamily() const;
-
-  // Continuously observe whether IPv6 is supported, and set the allowable
-  // address family to IPv4 iff IPv6 is not supported.
-  virtual void ProbeIPv6Support();
-
-  // Enable or disable the built-in asynchronous DnsClient.
-  virtual void SetDnsClientEnabled(bool enabled);
-
-  // Returns the HostResolverCache |this| uses, or NULL if there isn't one.
-  // Used primarily to clear the cache and for getting debug information.
-  virtual HostCache* GetHostCache();
-
-  // Returns the current DNS configuration |this| is using, as a Value, or NULL
-  // if it's configured to always use the system host resolver.  Caller takes
-  // ownership of the returned Value.
-  virtual base::Value* GetDnsConfigAsValue() const;
-
-  // Creates a HostResolver implementation that queries the underlying system.
-  // (Except if a unit-test has changed the global HostResolverProc using
-  // ScopedHostResolverProc to intercept requests to the system).
-  static scoped_ptr<HostResolver> CreateSystemResolver(
-      const Options& options,
-      NetLog* net_log);
-
-  // As above, but uses default parameters.
-  static scoped_ptr<HostResolver> CreateDefaultResolver(NetLog* net_log);
-
- protected:
-  HostResolver();
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(HostResolver);
-};
-
-}  // namespace net
-
-#endif  // NET_BASE_HOST_RESOLVER_H_