/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/* vim: set ts=2 et sw=2 tw=80: */

/* This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this file,

 * You can obtain one at http://mozilla.org/MPL/2.0/. */

// Original author: ekr@rtfm.com

#ifndef transportlayerdtls_h__

#define transportlayerdtls_h__

#include <queue>

#include <set>

#include "sigslot.h"

#include "mozilla/RefPtr.h"

#include "mozilla/UniquePtr.h"

#include "mozilla/TimeStamp.h"

#include "nsCOMPtr.h"

#include "nsIEventTarget.h"

#include "nsITimer.h"

#include "ScopedNSSTypes.h"

#include "m_cpp_utils.h"

#include "dtlsidentity.h"

#include "transportlayer.h"

#include "ssl.h"

namespace mozilla {

// RFC 5764 (we don't support the NULL cipher)

static const uint16_t kDtlsSrtpAes128CmHmacSha1_80 = 0x0001;

static const uint16_t kDtlsSrtpAes128CmHmacSha1_32 = 0x0002;

// RFC 7714

static const uint16_t kDtlsSrtpAeadAes128Gcm =       0x0007;

static const uint16_t kDtlsSrtpAeadAes256Gcm =       0x0008;

struct Packet;

class TransportLayerNSPRAdapter {

 public:

  explicit TransportLayerNSPRAdapter(TransportLayer *output) :

  output_(output),

  input_(),

  enabled_(true) {}

  void PacketReceived(MediaPacket& packet);

  int32_t Recv(void *buf, int32_t buflen);

  int32_t Write(const void *buf, int32_t length);

  void SetEnabled(bool enabled) { enabled_ = enabled; }

 private:

  DISALLOW_COPY_ASSIGN(TransportLayerNSPRAdapter);

  TransportLayer *output_;

  std::queue<MediaPacket *> input_;

  bool enabled_;

};

class TransportLayerDtls final : public TransportLayer {

 public:

  TransportLayerDtls() = default;

  virtual ~TransportLayerDtls();

  enum Role { CLIENT, SERVER};

  enum Verification { VERIFY_UNSET, VERIFY_ALLOW_ALL, VERIFY_DIGEST};

  const static size_t kMaxDigestLength = HASH_LENGTH_MAX;

  // DTLS-specific operations

  void SetRole(Role role) { role_ = role;}

  Role role() { return role_; }

  void SetIdentity(const RefPtr<DtlsIdentity>& identity) {

    identity_ = identity;

  }

  nsresult SetAlpn(const std::set<std::string>& allowedAlpn,

                   const std::string& alpnDefault);

  const std::string& GetNegotiatedAlpn() const { return alpn_; }

  nsresult SetVerificationAllowAll();

  nsresult SetVerificationDigest(const std::string digest_algorithm,

                                 const unsigned char *digest_value,

                                 size_t digest_len);

  nsresult GetCipherSuite(uint16_t* cipherSuite) const;

  nsresult SetSrtpCiphers(const std::vector<uint16_t>& ciphers);

  nsresult GetSrtpCipher(uint16_t *cipher) const;

  nsresult ExportKeyingMaterial(const std::string& label,

                                bool use_context,

                                const std::string& context,

                                unsigned char *out,

                                unsigned int outlen);

  // Transport layer overrides.

  nsresult InitInternal() override;

  void WasInserted() override;

  TransportResult SendPacket(MediaPacket& packet) override;

  // Signals

  void StateChange(TransportLayer *layer, State state);

  void PacketReceived(TransportLayer* layer, MediaPacket& packet);

  // For testing use only.  Returns the fd.

  PRFileDesc* internal_fd() { CheckThread(); return ssl_fd_.get(); }

  TRANSPORT_LAYER_ID("dtls")

  protected:

  void SetState(State state, const char *file, unsigned line) override;

  private:

  DISALLOW_COPY_ASSIGN(TransportLayerDtls);

  // A single digest to check

  class VerificationDigest {

   public:

    VerificationDigest(std::string algorithm,

                       const unsigned char *value, size_t len) {

      MOZ_ASSERT(len <= sizeof(value_));

      algorithm_ = algorithm;

      memcpy(value_, value, len);

      len_ = len;

    }

    NS_INLINE_DECL_THREADSAFE_REFCOUNTING(VerificationDigest)

    std::string algorithm_;

    size_t len_;

    unsigned char value_[kMaxDigestLength];

   private:

    ~VerificationDigest() {}

    DISALLOW_COPY_ASSIGN(VerificationDigest);

  };

  bool Setup();

  bool SetupCipherSuites(UniquePRFileDesc& ssl_fd);

  bool SetupAlpn(UniquePRFileDesc& ssl_fd) const;

  void GetDecryptedPackets();

  void Handshake();

  bool CheckAlpn();

  static SECStatus GetClientAuthDataHook(void *arg, PRFileDesc *fd,

                                         CERTDistNames *caNames,

                                         CERTCertificate **pRetCert,

                                         SECKEYPrivateKey **pRetKey);

  static SECStatus AuthCertificateHook(void *arg,

                                       PRFileDesc *fd,

                                       PRBool checksig,

                                       PRBool isServer);

  SECStatus AuthCertificateHook(PRFileDesc *fd,

                                PRBool checksig,

                                PRBool isServer);

  static void TimerCallback(nsITimer *timer, void *arg);

  SECStatus CheckDigest(const RefPtr<VerificationDigest>& digest,

                        UniqueCERTCertificate& cert) const;

  void RecordHandshakeCompletionTelemetry(TransportLayer::State endState);

  void RecordCipherTelemetry();

  static PRBool WriteSrtpXtn(PRFileDesc* fd, SSLHandshakeType message,

                             uint8_t* data, unsigned int* len,

                             unsigned int max_len, void* arg);

  static SECStatus HandleSrtpXtn(PRFileDesc* fd, SSLHandshakeType message,

                                 const uint8_t* data, unsigned int len,

                                 SSLAlertDescription* alert, void* arg);

  RefPtr<DtlsIdentity> identity_;

  // What ALPN identifiers are permitted.

  std::set<std::string> alpn_allowed_;

  // What ALPN identifier is used if ALPN is not supported.

  // The empty string indicates that ALPN is required.

  std::string alpn_default_;

  // What ALPN string was negotiated.

  std::string alpn_;

  std::vector<uint16_t> enabled_srtp_ciphers_;

  uint16_t srtp_cipher_ = 0;

  Role role_ = CLIENT;

  Verification verification_mode_ = VERIFY_UNSET;

  std::vector<RefPtr<VerificationDigest> > digests_;

  // Must delete nspr_io_adapter after ssl_fd_ b/c ssl_fd_ causes an alert

  // (ssl_fd_ contains an un-owning pointer to nspr_io_adapter_)

  UniquePtr<TransportLayerNSPRAdapter> nspr_io_adapter_ = nullptr;

  UniquePRFileDesc ssl_fd_ = nullptr;

  nsCOMPtr<nsITimer> timer_ = nullptr;

  bool auth_hook_called_ = false;

  bool cert_ok_ = false;

  TimeStamp handshake_started_;

};

}  // close namespace

#endif