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      1 /*
      2  * libjingle
      3  * Copyright 2011, Google Inc.
      4  * Copyright 2011, RTFM, Inc.
      5  *
      6  * Redistribution and use in source and binary forms, with or without
      7  * modification, are permitted provided that the following conditions are met:
      8  *
      9  *  1. Redistributions of source code must retain the above copyright notice,
     10  *     this list of conditions and the following disclaimer.
     11  *  2. Redistributions in binary form must reproduce the above copyright notice,
     12  *     this list of conditions and the following disclaimer in the documentation
     13  *     and/or other materials provided with the distribution.
     14  *  3. The name of the author may not be used to endorse or promote products
     15  *     derived from this software without specific prior written permission.
     16  *
     17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
     18  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
     19  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
     20  * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     21  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     22  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
     23  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
     24  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
     25  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
     26  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     27  */
     28 
     29 #ifndef TALK_P2P_BASE_DTLSTRANSPORTCHANNEL_H_
     30 #define TALK_P2P_BASE_DTLSTRANSPORTCHANNEL_H_
     31 
     32 #include <string>
     33 #include <vector>
     34 
     35 #include "talk/base/buffer.h"
     36 #include "talk/base/scoped_ptr.h"
     37 #include "talk/base/sslstreamadapter.h"
     38 #include "talk/base/stream.h"
     39 #include "talk/p2p/base/transportchannelimpl.h"
     40 
     41 namespace cricket {
     42 
     43 // A bridge between a packet-oriented/channel-type interface on
     44 // the bottom and a StreamInterface on the top.
     45 class StreamInterfaceChannel : public talk_base::StreamInterface,
     46                                public sigslot::has_slots<> {
     47  public:
     48   StreamInterfaceChannel(talk_base::Thread* owner, TransportChannel* channel)
     49       : channel_(channel),
     50         state_(talk_base::SS_OPEN),
     51         fifo_(kFifoSize, owner) {
     52     fifo_.SignalEvent.connect(this, &StreamInterfaceChannel::OnEvent);
     53   }
     54 
     55   // Push in a packet; this gets pulled out from Read().
     56   bool OnPacketReceived(const char* data, size_t size);
     57 
     58   // Implementations of StreamInterface
     59   virtual talk_base::StreamState GetState() const { return state_; }
     60   virtual void Close() { state_ = talk_base::SS_CLOSED; }
     61   virtual talk_base::StreamResult Read(void* buffer, size_t buffer_len,
     62                                        size_t* read, int* error);
     63   virtual talk_base::StreamResult Write(const void* data, size_t data_len,
     64                                         size_t* written, int* error);
     65 
     66  private:
     67   static const size_t kFifoSize = 8192;
     68 
     69   // Forward events
     70   virtual void OnEvent(talk_base::StreamInterface* stream, int sig, int err);
     71 
     72   TransportChannel* channel_;  // owned by DtlsTransportChannelWrapper
     73   talk_base::StreamState state_;
     74   talk_base::FifoBuffer fifo_;
     75 
     76   DISALLOW_COPY_AND_ASSIGN(StreamInterfaceChannel);
     77 };
     78 
     79 
     80 // This class provides a DTLS SSLStreamAdapter inside a TransportChannel-style
     81 // packet-based interface, wrapping an existing TransportChannel instance
     82 // (e.g a P2PTransportChannel)
     83 // Here's the way this works:
     84 //
     85 //   DtlsTransportChannelWrapper {
     86 //       SSLStreamAdapter* dtls_ {
     87 //           StreamInterfaceChannel downward_ {
     88 //               TransportChannelImpl* channel_;
     89 //           }
     90 //       }
     91 //   }
     92 //
     93 //   - Data which comes into DtlsTransportChannelWrapper from the underlying
     94 //     channel_ via OnReadPacket() is checked for whether it is DTLS
     95 //     or not, and if it is, is passed to DtlsTransportChannelWrapper::
     96 //     HandleDtlsPacket, which pushes it into to downward_.
     97 //     dtls_ is listening for events on downward_, so it immediately calls
     98 //     downward_->Read().
     99 //
    100 //   - Data written to DtlsTransportChannelWrapper is passed either to
    101 //      downward_ or directly to channel_, depending on whether DTLS is
    102 //     negotiated and whether the flags include PF_SRTP_BYPASS
    103 //
    104 //   - The SSLStreamAdapter writes to downward_->Write()
    105 //     which translates it into packet writes on channel_.
    106 class DtlsTransportChannelWrapper : public TransportChannelImpl {
    107  public:
    108     enum State {
    109       STATE_NONE,      // No state or rejected.
    110       STATE_OFFERED,   // Our identity has been set.
    111       STATE_ACCEPTED,  // The other side sent a fingerprint.
    112       STATE_STARTED,   // We are negotiating.
    113       STATE_OPEN,      // Negotiation complete.
    114       STATE_CLOSED     // Connection closed.
    115     };
    116 
    117   // The parameters here are:
    118   // transport -- the DtlsTransport that created us
    119   // channel -- the TransportChannel we are wrapping
    120   DtlsTransportChannelWrapper(Transport* transport,
    121                               TransportChannelImpl* channel);
    122   virtual ~DtlsTransportChannelWrapper();
    123 
    124   virtual void SetIceRole(IceRole role) {
    125     channel_->SetIceRole(role);
    126   }
    127   virtual IceRole GetIceRole() const {
    128     return channel_->GetIceRole();
    129   }
    130   virtual size_t GetConnectionCount() const {
    131     return channel_->GetConnectionCount();
    132   }
    133   virtual bool SetLocalIdentity(talk_base::SSLIdentity *identity);
    134   virtual bool GetLocalIdentity(talk_base::SSLIdentity** identity) const;
    135 
    136   virtual bool SetRemoteFingerprint(const std::string& digest_alg,
    137                                     const uint8* digest,
    138                                     size_t digest_len);
    139   virtual bool IsDtlsActive() const { return dtls_state_ != STATE_NONE; }
    140 
    141   // Called to send a packet (via DTLS, if turned on).
    142   virtual int SendPacket(const char* data, size_t size,
    143                          const talk_base::PacketOptions& options,
    144                          int flags);
    145 
    146   // TransportChannel calls that we forward to the wrapped transport.
    147   virtual int SetOption(talk_base::Socket::Option opt, int value) {
    148     return channel_->SetOption(opt, value);
    149   }
    150   virtual int GetError() {
    151     return channel_->GetError();
    152   }
    153   virtual bool GetStats(ConnectionInfos* infos) {
    154     return channel_->GetStats(infos);
    155   }
    156   virtual const std::string SessionId() const {
    157     return channel_->SessionId();
    158   }
    159 
    160   // Set up the ciphers to use for DTLS-SRTP. If this method is not called
    161   // before DTLS starts, or |ciphers| is empty, SRTP keys won't be negotiated.
    162   // This method should be called before SetupDtls.
    163   virtual bool SetSrtpCiphers(const std::vector<std::string>& ciphers);
    164 
    165   // Find out which DTLS-SRTP cipher was negotiated
    166   virtual bool GetSrtpCipher(std::string* cipher);
    167 
    168   virtual bool GetSslRole(talk_base::SSLRole* role) const;
    169   virtual bool SetSslRole(talk_base::SSLRole role);
    170 
    171   // Once DTLS has been established, this method retrieves the certificate in
    172   // use by the remote peer, for use in external identity verification.
    173   virtual bool GetRemoteCertificate(talk_base::SSLCertificate** cert) const;
    174 
    175   // Once DTLS has established (i.e., this channel is writable), this method
    176   // extracts the keys negotiated during the DTLS handshake, for use in external
    177   // encryption. DTLS-SRTP uses this to extract the needed SRTP keys.
    178   // See the SSLStreamAdapter documentation for info on the specific parameters.
    179   virtual bool ExportKeyingMaterial(const std::string& label,
    180                                     const uint8* context,
    181                                     size_t context_len,
    182                                     bool use_context,
    183                                     uint8* result,
    184                                     size_t result_len) {
    185     return (dtls_.get()) ? dtls_->ExportKeyingMaterial(label, context,
    186                                                        context_len,
    187                                                        use_context,
    188                                                        result, result_len)
    189         : false;
    190   }
    191 
    192   // TransportChannelImpl calls.
    193   virtual Transport* GetTransport() {
    194     return transport_;
    195   }
    196   virtual void SetIceTiebreaker(uint64 tiebreaker) {
    197     channel_->SetIceTiebreaker(tiebreaker);
    198   }
    199   virtual bool GetIceProtocolType(IceProtocolType* type) const {
    200     return channel_->GetIceProtocolType(type);
    201   }
    202   virtual void SetIceProtocolType(IceProtocolType type) {
    203     channel_->SetIceProtocolType(type);
    204   }
    205   virtual void SetIceCredentials(const std::string& ice_ufrag,
    206                                  const std::string& ice_pwd) {
    207     channel_->SetIceCredentials(ice_ufrag, ice_pwd);
    208   }
    209   virtual void SetRemoteIceCredentials(const std::string& ice_ufrag,
    210                                        const std::string& ice_pwd) {
    211     channel_->SetRemoteIceCredentials(ice_ufrag, ice_pwd);
    212   }
    213   virtual void SetRemoteIceMode(IceMode mode) {
    214     channel_->SetRemoteIceMode(mode);
    215   }
    216 
    217   virtual void Connect();
    218   virtual void Reset();
    219 
    220   virtual void OnSignalingReady() {
    221     channel_->OnSignalingReady();
    222   }
    223   virtual void OnCandidate(const Candidate& candidate) {
    224     channel_->OnCandidate(candidate);
    225   }
    226 
    227   // Needed by DtlsTransport.
    228   TransportChannelImpl* channel() { return channel_; }
    229 
    230  private:
    231   void OnReadableState(TransportChannel* channel);
    232   void OnWritableState(TransportChannel* channel);
    233   void OnReadPacket(TransportChannel* channel, const char* data, size_t size,
    234                     const talk_base::PacketTime& packet_time, int flags);
    235   void OnReadyToSend(TransportChannel* channel);
    236   void OnDtlsEvent(talk_base::StreamInterface* stream_, int sig, int err);
    237   bool SetupDtls();
    238   bool MaybeStartDtls();
    239   bool HandleDtlsPacket(const char* data, size_t size);
    240   void OnRequestSignaling(TransportChannelImpl* channel);
    241   void OnCandidateReady(TransportChannelImpl* channel, const Candidate& c);
    242   void OnCandidatesAllocationDone(TransportChannelImpl* channel);
    243   void OnRoleConflict(TransportChannelImpl* channel);
    244   void OnRouteChange(TransportChannel* channel, const Candidate& candidate);
    245   void OnConnectionRemoved(TransportChannelImpl* channel);
    246 
    247   Transport* transport_;  // The transport_ that created us.
    248   talk_base::Thread* worker_thread_;  // Everything should occur on this thread.
    249   TransportChannelImpl* channel_;  // Underlying channel, owned by transport_.
    250   talk_base::scoped_ptr<talk_base::SSLStreamAdapter> dtls_;  // The DTLS stream
    251   StreamInterfaceChannel* downward_;  // Wrapper for channel_, owned by dtls_.
    252   std::vector<std::string> srtp_ciphers_;  // SRTP ciphers to use with DTLS.
    253   State dtls_state_;
    254   talk_base::SSLIdentity* local_identity_;
    255   talk_base::SSLRole ssl_role_;
    256   talk_base::Buffer remote_fingerprint_value_;
    257   std::string remote_fingerprint_algorithm_;
    258 
    259   DISALLOW_COPY_AND_ASSIGN(DtlsTransportChannelWrapper);
    260 };
    261 
    262 }  // namespace cricket
    263 
    264 #endif  // TALK_P2P_BASE_DTLSTRANSPORTCHANNEL_H_
    265