gecko-dev/media/mtransport/transportlayerdtls.h

/* -*- 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