// 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_SOCKET_SSL_CLIENT_SOCKET_H_
#define NET_SOCKET_SSL_CLIENT_SOCKET_H_

#include <string>

#include "base/gtest_prod_util.h"
#include "net/base/completion_callback.h"
#include "net/base/load_flags.h"
#include "net/base/net_errors.h"
#include "net/socket/ssl_socket.h"
#include "net/socket/stream_socket.h"
#include "net/ssl/ssl_failure_state.h"

namespace net {

class CertPolicyEnforcer;
class CertVerifier;
class ChannelIDService;
class CTVerifier;
class SSLCertRequestInfo;
struct SSLConfig;
class SSLInfo;
class TransportSecurityState;
class X509Certificate;

// This struct groups together several fields which are used by various
// classes related to SSLClientSocket.
struct SSLClientSocketContext {
  SSLClientSocketContext()
      : cert_verifier(NULL),
        channel_id_service(NULL),
        transport_security_state(NULL),
        cert_transparency_verifier(NULL),
        cert_policy_enforcer(NULL) {}

  SSLClientSocketContext(CertVerifier* cert_verifier_arg,
                         ChannelIDService* channel_id_service_arg,
                         TransportSecurityState* transport_security_state_arg,
                         CTVerifier* cert_transparency_verifier_arg,
                         CertPolicyEnforcer* cert_policy_enforcer_arg,
                         const std::string& ssl_session_cache_shard_arg)
      : cert_verifier(cert_verifier_arg),
        channel_id_service(channel_id_service_arg),
        transport_security_state(transport_security_state_arg),
        cert_transparency_verifier(cert_transparency_verifier_arg),
        cert_policy_enforcer(cert_policy_enforcer_arg),
        ssl_session_cache_shard(ssl_session_cache_shard_arg) {}

  CertVerifier* cert_verifier;
  ChannelIDService* channel_id_service;
  TransportSecurityState* transport_security_state;
  CTVerifier* cert_transparency_verifier;
  CertPolicyEnforcer* cert_policy_enforcer;
  // ssl_session_cache_shard is an opaque string that identifies a shard of the
  // SSL session cache. SSL sockets with the same ssl_session_cache_shard may
  // resume each other's SSL sessions but we'll never sessions between shards.
  const std::string ssl_session_cache_shard;
};

// A client socket that uses SSL as the transport layer.
//
// NOTE: The SSL handshake occurs within the Connect method after a TCP
// connection is established.  If a SSL error occurs during the handshake,
// Connect will fail.
//
class NET_EXPORT SSLClientSocket : public SSLSocket {
 public:
  SSLClientSocket();

  // Next Protocol Negotiation (NPN) allows a TLS client and server to come to
  // an agreement about the application level protocol to speak over a
  // connection.
  enum NextProtoStatus {
    // WARNING: These values are serialized to disk. Don't change them.

    kNextProtoUnsupported = 0,  // The server doesn't support NPN.
    kNextProtoNegotiated = 1,   // We agreed on a protocol.
    kNextProtoNoOverlap = 2,    // No protocols in common. We requested
                                // the first protocol in our list.
  };

  // TLS extension used to negotiate protocol.
  enum SSLNegotiationExtension {
    kExtensionUnknown,
    kExtensionALPN,
    kExtensionNPN,
  };

  // StreamSocket:
  bool WasNpnNegotiated() const override;
  NextProto GetNegotiatedProtocol() const override;

  // Gets the SSL CertificateRequest info of the socket after Connect failed
  // with ERR_SSL_CLIENT_AUTH_CERT_NEEDED.
  virtual void GetSSLCertRequestInfo(
      SSLCertRequestInfo* cert_request_info) = 0;

  // Get the application level protocol that we negotiated with the server.
  // *proto is set to the resulting protocol (n.b. that the string may have
  // embedded NULs).
  //   kNextProtoUnsupported: *proto is cleared.
  //   kNextProtoNegotiated:  *proto is set to the negotiated protocol.
  //   kNextProtoNoOverlap:   *proto is set to the first protocol in the
  //                          supported list.
  virtual NextProtoStatus GetNextProto(std::string* proto) const = 0;

  static NextProto NextProtoFromString(const std::string& proto_string);

  static const char* NextProtoToString(NextProto next_proto);

  static const char* NextProtoStatusToString(const NextProtoStatus status);

  // Returns true if |error| is OK or |load_flags| ignores certificate errors
  // and |error| is a certificate error.
  static bool IgnoreCertError(int error, int load_flags);

  // ClearSessionCache clears the SSL session cache, used to resume SSL
  // sessions.
  static void ClearSessionCache();

  // Get the maximum SSL version supported by the underlying library and
  // cryptographic implementation.
  static uint16 GetMaxSupportedSSLVersion();

  // Returns the ChannelIDService used by this socket, or NULL if
  // channel ids are not supported.
  virtual ChannelIDService* GetChannelIDService() const = 0;

  // Returns the state of the handshake when it failed, or |SSL_FAILURE_NONE| if
  // the handshake succeeded. This is used to classify causes of the TLS version
  // fallback.
  virtual SSLFailureState GetSSLFailureState() const = 0;

 protected:
  void set_negotiation_extension(
      SSLNegotiationExtension negotiation_extension) {
    negotiation_extension_ = negotiation_extension;
  }

  void set_signed_cert_timestamps_received(
      bool signed_cert_timestamps_received) {
    signed_cert_timestamps_received_ = signed_cert_timestamps_received;
  }

  void set_stapled_ocsp_response_received(bool stapled_ocsp_response_received) {
    stapled_ocsp_response_received_ = stapled_ocsp_response_received;
  }

  // Record which TLS extension was used to negotiate protocol and protocol
  // chosen in a UMA histogram.
  void RecordNegotiationExtension();

  // Records histograms for channel id support during full handshakes - resumed
  // handshakes are ignored.
  static void RecordChannelIDSupport(
      ChannelIDService* channel_id_service,
      bool negotiated_channel_id,
      bool channel_id_enabled,
      bool supports_ecc);

  // Returns whether TLS channel ID is enabled.
  static bool IsChannelIDEnabled(
      const SSLConfig& ssl_config,
      ChannelIDService* channel_id_service);

  // Determine if there is at least one enabled cipher suite that satisfies
  // Section 9.2 of the HTTP/2 specification.  Note that the server might still
  // pick an inadequate cipher suite.
  static bool HasCipherAdequateForHTTP2(
      const std::vector<uint16>& cipher_suites);

  // Determine if the TLS version required by Section 9.2 of the HTTP/2
  // specification is enabled.  Note that the server might still pick an
  // inadequate TLS version.
  static bool IsTLSVersionAdequateForHTTP2(const SSLConfig& ssl_config);

  // Serializes |next_protos| in the wire format for ALPN: protocols are listed
  // in order, each prefixed by a one-byte length.  Any HTTP/2 protocols in
  // |next_protos| are ignored if |can_advertise_http2| is false.
  static std::vector<uint8_t> SerializeNextProtos(
      const NextProtoVector& next_protos,
      bool can_advertise_http2);

  // For unit testing only.
  // Returns the unverified certificate chain as presented by server.
  // Note that chain may be different than the verified chain returned by
  // StreamSocket::GetSSLInfo().
  virtual scoped_refptr<X509Certificate> GetUnverifiedServerCertificateChain()
      const = 0;

 private:
  FRIEND_TEST_ALL_PREFIXES(SSLClientSocket, SerializeNextProtos);
  // For signed_cert_timestamps_received_ and stapled_ocsp_response_received_.
  FRIEND_TEST_ALL_PREFIXES(SSLClientSocketTest,
                           ConnectSignedCertTimestampsEnabledTLSExtension);
  FRIEND_TEST_ALL_PREFIXES(SSLClientSocketTest,
                           ConnectSignedCertTimestampsEnabledOCSP);
  FRIEND_TEST_ALL_PREFIXES(SSLClientSocketTest,
                           ConnectSignedCertTimestampsDisabled);
  FRIEND_TEST_ALL_PREFIXES(SSLClientSocketTest,
                           VerifyServerChainProperlyOrdered);

  // True if SCTs were received via a TLS extension.
  bool signed_cert_timestamps_received_;
  // True if a stapled OCSP response was received.
  bool stapled_ocsp_response_received_;
  // Protocol negotiation extension used.
  SSLNegotiationExtension negotiation_extension_;
};

}  // namespace net

#endif  // NET_SOCKET_SSL_CLIENT_SOCKET_H_