Home | History | Annotate | Download | only in base 
      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 ice_role);
    125   // Returns current transport role of the channel.
    126   virtual IceRole GetIceRole() const {
    127     return channel_->GetIceRole();
    128   }
    129   virtual bool SetLocalIdentity(talk_base::SSLIdentity *identity);
    130 
    131   virtual bool SetRemoteFingerprint(const std::string& digest_alg,
    132                                     const uint8* digest,
    133                                     size_t digest_len);
    134   virtual bool IsDtlsActive() const { return dtls_state_ != STATE_NONE; }
    135 
    136   // Called to send a packet (via DTLS, if turned on).
    137   virtual int SendPacket(const char* data, size_t size, int flags);
    138 
    139   // TransportChannel calls that we forward to the wrapped transport.
    140   virtual int SetOption(talk_base::Socket::Option opt, int value) {
    141     return channel_->SetOption(opt, value);
    142   }
    143   virtual int GetError() {
    144     return channel_->GetError();
    145   }
    146   virtual bool GetStats(ConnectionInfos* infos) {
    147     return channel_->GetStats(infos);
    148   }
    149   virtual const std::string SessionId() const {
    150     return channel_->SessionId();
    151   }
    152 
    153   // Set up the ciphers to use for DTLS-SRTP. If this method is not called
    154   // before DTLS starts, or |ciphers| is empty, SRTP keys won't be negotiated.
    155   // This method should be called before SetupDtls.
    156   virtual bool SetSrtpCiphers(const std::vector<std::string>& ciphers);
    157 
    158   // Find out which DTLS-SRTP cipher was negotiated
    159   virtual bool GetSrtpCipher(std::string* cipher);
    160 
    161   // Once DTLS has established (i.e., this channel is writable), this method
    162   // extracts the keys negotiated during the DTLS handshake, for use in external
    163   // encryption. DTLS-SRTP uses this to extract the needed SRTP keys.
    164   // See the SSLStreamAdapter documentation for info on the specific parameters.
    165   virtual bool ExportKeyingMaterial(const std::string& label,
    166                                     const uint8* context,
    167                                     size_t context_len,
    168                                     bool use_context,
    169                                     uint8* result,
    170                                     size_t result_len) {
    171     return (dtls_.get()) ? dtls_->ExportKeyingMaterial(label, context,
    172                                                        context_len,
    173                                                        use_context,
    174                                                        result, result_len)
    175         : false;
    176   }
    177 
    178   // TransportChannelImpl calls.
    179   virtual Transport* GetTransport() {
    180     return transport_;
    181   }
    182   virtual void SetIceTiebreaker(uint64 tiebreaker) {
    183     channel_->SetIceTiebreaker(tiebreaker);
    184   }
    185   virtual void SetIceProtocolType(IceProtocolType type) {
    186     channel_->SetIceProtocolType(type);
    187   }
    188   virtual void SetIceCredentials(const std::string& ice_ufrag,
    189                                  const std::string& ice_pwd) {
    190     channel_->SetIceCredentials(ice_ufrag, ice_pwd);
    191   }
    192   virtual void SetRemoteIceCredentials(const std::string& ice_ufrag,
    193                                        const std::string& ice_pwd) {
    194     channel_->SetRemoteIceCredentials(ice_ufrag, ice_pwd);
    195   }
    196   virtual void SetRemoteIceMode(IceMode mode) {
    197     channel_->SetRemoteIceMode(mode);
    198   }
    199 
    200   virtual void Connect();
    201   virtual void Reset();
    202 
    203   virtual void OnSignalingReady() {
    204     channel_->OnSignalingReady();
    205   }
    206   virtual void OnCandidate(const Candidate& candidate) {
    207     channel_->OnCandidate(candidate);
    208   }
    209 
    210   // Needed by DtlsTransport.
    211   TransportChannelImpl* channel() { return channel_; }
    212 
    213  private:
    214   void OnReadableState(TransportChannel* channel);
    215   void OnWritableState(TransportChannel* channel);
    216   void OnReadPacket(TransportChannel* channel, const char* data, size_t size,
    217                     int flags);
    218   void OnReadyToSend(TransportChannel* channel);
    219   void OnDtlsEvent(talk_base::StreamInterface* stream_, int sig, int err);
    220   bool SetupDtls();
    221   bool MaybeStartDtls();
    222   bool HandleDtlsPacket(const char* data, size_t size);
    223   void OnRequestSignaling(TransportChannelImpl* channel);
    224   void OnCandidateReady(TransportChannelImpl* channel, const Candidate& c);
    225   void OnCandidatesAllocationDone(TransportChannelImpl* channel);
    226   void OnRoleConflict(TransportChannelImpl* channel);
    227   void OnRouteChange(TransportChannel* channel, const Candidate& candidate);
    228 
    229   Transport* transport_;  // The transport_ that created us.
    230   talk_base::Thread* worker_thread_;  // Everything should occur on this thread.
    231   TransportChannelImpl* channel_;  // Underlying channel, owned by transport_.
    232   talk_base::scoped_ptr<talk_base::SSLStreamAdapter> dtls_;  // The DTLS stream
    233   StreamInterfaceChannel* downward_;  // Wrapper for channel_, owned by dtls_.
    234   std::vector<std::string> srtp_ciphers_;  // SRTP ciphers to use with DTLS.
    235   State dtls_state_;
    236   talk_base::SSLIdentity* local_identity_;
    237   talk_base::SSLRole dtls_role_;
    238   talk_base::Buffer remote_fingerprint_value_;
    239   std::string remote_fingerprint_algorithm_;
    240 
    241   DISALLOW_COPY_AND_ASSIGN(DtlsTransportChannelWrapper);
    242 };
    243 
    244 }  // namespace cricket
    245 
    246 #endif  // TALK_P2P_BASE_DTLSTRANSPORTCHANNEL_H_
    247