Line data    Source code

       1             : /*
       2             :     Mosh: the mobile shell
       3             :     Copyright 2012 Keith Winstein
       4             : 
       5             :     This program is free software: you can redistribute it and/or modify
       6             :     it under the terms of the GNU General Public License as published by
       7             :     the Free Software Foundation, either version 3 of the License, or
       8             :     (at your option) any later version.
       9             : 
      10             :     This program is distributed in the hope that it will be useful,
      11             :     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12             :     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      13             :     GNU General Public License for more details.
      14             : 
      15             :     You should have received a copy of the GNU General Public License
      16             :     along with this program.  If not, see <http://www.gnu.org/licenses/>.
      17             : 
      18             :     In addition, as a special exception, the copyright holders give
      19             :     permission to link the code of portions of this program with the
      20             :     OpenSSL library under certain conditions as described in each
      21             :     individual source file, and distribute linked combinations including
      22             :     the two.
      23             : 
      24             :     You must obey the GNU General Public License in all respects for all
      25             :     of the code used other than OpenSSL. If you modify file(s) with this
      26             :     exception, you may extend this exception to your version of the
      27             :     file(s), but you are not obligated to do so. If you do not wish to do
      28             :     so, delete this exception statement from your version. If you delete
      29             :     this exception statement from all source files in the program, then
      30             :     also delete it here.
      31             : */
      32             : 
      33             : 
      34             : #ifndef TRANSPORT_SENDER_HPP
      35             : #define TRANSPORT_SENDER_HPP
      36             : 
      37             : #include <string>
      38             : #include <list>
      39             : 
      40             : #include "network.h"
      41             : #include "transportinstruction.pb.h"
      42             : #include "transportstate.h"
      43             : #include "transportfragment.h"
      44             : #include "prng.h"
      45             : 
      46             : namespace Network {
      47             :   using std::list;
      48             :   using std::pair;
      49             :   using namespace TransportBuffers;
      50             : 
      51             :   /* timing parameters */
      52             :   const int SEND_INTERVAL_MIN = 20; /* ms between frames */
      53             :   const int SEND_INTERVAL_MAX = 250; /* ms between frames */
      54             :   const int ACK_INTERVAL = 3000; /* ms between empty acks */
      55             :   const int ACK_DELAY = 100; /* ms before delayed ack */
      56             :   const int SHUTDOWN_RETRIES = 16; /* number of shutdown packets to send before giving up */
      57             :   const int ACTIVE_RETRY_TIMEOUT = 10000; /* attempt to resend at frame rate */
      58             : 
      59             :   template <class MyState>
      60             :   class TransportSender
      61             :   {
      62             :   private:
      63             :     /* helper methods for tick() */
      64             :     void update_assumed_receiver_state( void );
      65             :     void attempt_prospective_resend_optimization( string &proposed_diff );
      66             :     void rationalize_states( void );
      67             :     void send_to_receiver( const string & diff );
      68             :     void send_empty_ack( void );
      69             :     void send_in_fragments( const string & diff, uint64_t new_num );
      70             :     void add_sent_state( uint64_t the_timestamp, uint64_t num, MyState &state );
      71             : 
      72             :     /* state of sender */
      73             :     Connection *connection;
      74             : 
      75             :     MyState current_state;
      76             : 
      77             :     typedef list< TimestampedState<MyState> > sent_states_type;
      78             :     sent_states_type sent_states;
      79             :     /* first element: known, acknowledged receiver state */
      80             :     /* last element: last sent state */
      81             : 
      82             :     /* somewhere in the middle: the assumed state of the receiver */
      83             :     typename sent_states_type::iterator assumed_receiver_state;
      84             : 
      85             :     /* for fragment creation */
      86             :     Fragmenter fragmenter;
      87             : 
      88             :     /* timing state */
      89             :     uint64_t next_ack_time;
      90             :     uint64_t next_send_time;
      91             : 
      92             :     void calculate_timers( void );
      93             : 
      94             :     unsigned int verbose;
      95             :     bool shutdown_in_progress;
      96             :     int shutdown_tries;
      97             :     uint64_t shutdown_start;
      98             : 
      99             :     /* information about receiver state */
     100             :     uint64_t ack_num;
     101             :     bool pending_data_ack;
     102             : 
     103             :     unsigned int SEND_MINDELAY; /* ms to collect all input */
     104             : 
     105             :     uint64_t last_heard; /* last time received new state */
     106             : 
     107             :     /* chaff to disguise instruction length */
     108             :     PRNG prng;
     109             :     const string make_chaff( void );
     110             : 
     111             :     uint64_t mindelay_clock; /* time of first pending change to current state */
     112             : 
     113             :   public:
     114             :     /* constructor */
     115             :     TransportSender( Connection *s_connection, MyState &initial_state );
     116             : 
     117             :     /* Send data or an ack if necessary */
     118             :     void tick( void );
     119             : 
     120             :     /* Returns the number of ms to wait until next possible event. */
     121             :     int wait_time( void );
     122             : 
     123             :     /* Executed upon receipt of ack */
     124             :     void process_acknowledgment_through( uint64_t ack_num );
     125             : 
     126             :     /* Executed upon entry to new receiver state */
     127             :     void set_ack_num( uint64_t s_ack_num );
     128             : 
     129             :     /* Accelerate reply ack */
     130        3659 :     void set_data_ack( void ) { pending_data_ack = true; }
     131             : 
     132             :     /* Received something */
     133        5109 :     void remote_heard( uint64_t ts ) { last_heard = ts; }
     134             : 
     135             :     /* Starts shutdown sequence */
     136         452 :     void start_shutdown( void ) { if ( !shutdown_in_progress ) { shutdown_start = timestamp(); shutdown_in_progress = true; } }
     137             : 
     138             :     /* Misc. getters and setters */
     139             :     /* Cannot modify current_state while shutdown in progress */
     140        1675 :     MyState &get_current_state( void ) { assert( !shutdown_in_progress ); return current_state; }
     141       23153 :     void set_current_state( const MyState &x )
     142             :     {
     143       23153 :       assert( !shutdown_in_progress );
     144       23153 :       current_state = x;
     145       23153 :       current_state.reset_input();
     146       23153 :     }
     147         900 :     void set_verbose( unsigned int s_verbose ) { verbose = s_verbose; }
     148             : 
     149      117685 :     bool get_shutdown_in_progress( void ) const { return shutdown_in_progress; }
     150        1473 :     bool get_shutdown_acknowledged( void ) const { return sent_states.front().num == uint64_t(-1); }
     151       32680 :     bool get_counterparty_shutdown_acknowledged( void ) const { return fragmenter.last_ack_sent() == uint64_t(-1); }
     152        8614 :     uint64_t get_sent_state_acked_timestamp( void ) const { return sent_states.front().timestamp; }
     153        3333 :     uint64_t get_sent_state_acked( void ) const { return sent_states.front().num; }
     154         659 :     uint64_t get_sent_state_last( void ) const { return sent_states.back().num; }
     155             : 
     156             :     bool shutdown_ack_timed_out( void ) const;
     157             : 
     158         448 :     void set_send_delay( int new_delay ) { SEND_MINDELAY = new_delay; }
     159             : 
     160             :     unsigned int send_interval( void ) const;
     161             : 
     162             :     /* nonexistent methods to satisfy -Weffc++ */
     163             :     TransportSender( const TransportSender &x );
     164             :     TransportSender & operator=( const TransportSender &x );
     165             :   };
     166             : }
     167             : 
     168             : #endif