Successfully sends and receives simple KeyStrokes over UDP

Makefile

@@ -4,7 +4,7 @@ repos = templates.rpo
 executables = parse termemu ntester
 
 CXX = g++
-CXXFLAGS = -g -O2 --std=c++0x -pedantic -Werror -Wall -Wextra -Weffc++ -fno-implicit-templates -fno-default-inline -pipe -D_FILE_OFFSET_BITS=64 -D_XOPEN_SOURCE=500 -D_GNU_SOURCE
+CXXFLAGS = -g --std=c++0x -pedantic -Werror -Wall -Wextra -Weffc++ -fno-implicit-templates -fno-default-inline -pipe -D_FILE_OFFSET_BITS=64 -D_XOPEN_SOURCE=500 -D_GNU_SOURCE
 LIBS = -lutil
 
 all: $(executables)

dos_assert.hpp

@@ -0,0 +1,19 @@
+#ifndef DOS_ASSERT_HPP
+#define DOS_ASSERT_HPP
+
+#include <stdio.h>
+#include <stdlib.h>
+
+static void dos_detected( const char *expression, const char *file, int line, const char *function )
+{
+  fprintf( stderr, "Illegal counterparty input (possible DOS) in function %s at %s:%d, failed test: %s\n",
+	   function, file, line, expression );
+  exit( 1 );
+}
+
+#define dos_assert(expr)						\
+  ((expr)								\
+   ? (void)0								\
+   : dos_detected (__STRING(expr), __FILE__, __LINE__, __PRETTY_FUNCTION__ ))
+
+#endif

keystroke.hpp

@@ -0,0 +1,30 @@
+#ifndef KEYSTROKE_HPP
+#define KEYSTROKE_HPP
+
+#include <string>
+#include <assert.h>
+
+class KeyStroke
+{
+public:
+  char letter;
+
+  string tostring( void )
+  {
+    return string( &letter, 1 );
+  };
+
+  KeyStroke( const string x )
+    : letter()
+  {
+    assert( x.size() == 1 );
+
+    letter = x[ 0 ];
+  }
+
+  KeyStroke()
+    : letter( 0 )
+  {}
+};
+
+#endif

network.cpp

@@ -1,32 +1,171 @@
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
 #include <assert.h>
 
+#include "dos_assert.hpp"
 #include "network.hpp"
 
 using namespace std;
 using namespace Network;
 
 template <class Payload>
-Connection<Payload>::Packet::Packet( int64_t s_seq, int64_t s_ack, Packet *s_previous, Payload s_state )
-  : seq( s_seq ), ack( s_ack ), previous( s_previous ), state( s_state )
+Flow<Payload>::Packet::DecodingCache::DecodingCache( string coded_packet )
+  : direction( TO_CLIENT ), seq( -1 ), payload_string()
 {
+  dos_assert( coded_packet.size() >= 8 );
 
+  /* Read in sequence number and direction */
+  string seq_string( coded_packet.begin(), coded_packet.begin() + 8 );
+  uint64_t *network_order_seq = (uint64_t *)seq_string.data();
+  uint64_t direction_seq = be64toh( *network_order_seq );
+  direction = (direction_seq & 8000000000000000) ? TO_CLIENT : TO_SERVER;
+  seq = direction_seq & 0x7FFFFFFFFFFFFFFF;
+
+  /* Read in payload */
+  payload_string = string( coded_packet.begin() + 8, coded_packet.end() );  
 }
 
 template <class Payload>
-Connection<Payload>::Packet::Packet( string wire )
+Flow<Payload>::Packet::Packet( string coded_packet )
+  : decoding_cache( coded_packet ),
+    seq( decoding_cache.seq ),
+    direction( decoding_cache.direction ),
+    payload( decoding_cache.payload_string )
+{}
+
+template <class Payload>
+string Flow<Payload>::Packet::tostring( void )
 {
-  assert( wire.length() >= 32 );
+  uint64_t direction_seq = ((uint64_t( direction == TO_CLIENT ) & 0x1) << 63) | (seq & 0x7FFFFFFFFFFFFFFF);
+  uint64_t network_order_seq = htobe64( direction_seq );
+  const char *seq_str = (const char *)&network_order_seq;
+  string seq_string( seq_str, 8 ); /* necessary in case there is a zero byte */
 
-  seq = be64toh( (uint64_t) *wire_c );
-  reference_seq = be64toh( (uint64_t) *( wire_c + 8 ) );
-
-  tag = string( wire.begin() + 16, wire.begin() + 32 );
-
-  ack = be64toh( (uint64_t) *( wire_c + 16 ) );
+  return seq_string + payload.tostring();
 }
 
 template <class Payload>
-Connection<Payload>::Connection( const char *ip, const char *port, bool server )
+typename Flow<Payload>::Packet Flow<Payload>::new_packet( Payload &s_payload )
+{
+  return Packet( next_seq++, direction, s_payload );
+}
+
+template <class Outgoing, class Incoming>
+Connection<Outgoing, Incoming>::Connection( bool s_server )
+  : flow( s_server ? TO_CLIENT : TO_SERVER ),
+    sock( -1 ),
+    remote_addr(),
+    server( s_server ),
+    attached( false )
 {
 
+  /* create socket */
+  sock = socket( AF_INET, SOCK_DGRAM, 0 );
+  if ( sock < 0 ) {
+    perror( "socket" );
+    exit( 1 );
+  }
+
+  /* Bind to free local port.
+     This usage does not seem to be endorsed by POSIX. */
+  struct sockaddr_in local_addr;
+  local_addr.sin_family = AF_INET;
+  local_addr.sin_port = htons( 0 );
+  local_addr.sin_addr.s_addr = INADDR_ANY;
+  if ( bind( sock, (sockaddr *)&local_addr, sizeof( local_addr ) ) < 0 ) {
+    perror( "bind" );
+    exit( 1 );
+  }
+}
+
+template <class Outgoing, class Incoming>
+void Connection<Outgoing, Incoming>::client_connect( const char *ip, int port )
+{
+  assert( !server );
+
+  /* associate socket with remote host and port */
+  remote_addr.sin_family = AF_INET;
+  remote_addr.sin_port = htons( port );
+  if ( !inet_aton( ip, &remote_addr.sin_addr ) ) {
+    fprintf( stderr, "Bad IP address %s\n", ip );
+    exit( 1 );
+  }
+
+  if ( connect( sock, (sockaddr *)&remote_addr, sizeof( remote_addr ) ) < 0 ) {
+    perror( "connect" );
+    exit( 1 );
+  }
+
+  attached = true;
+}
+
+template <class Outgoing, class Incoming>
+void Connection<Outgoing, Incoming>::send( Outgoing &s )
+{
+  assert( attached );
+
+  string p = flow.new_packet( s ).tostring();
+
+  if ( sendto( sock, p.data(), p.size(), 0,
+	       (sockaddr *)&remote_addr, sizeof( remote_addr ) ) < 0 ) {
+    perror( "sendto" );
+    exit( 1 );
+  }
+}
+
+template <class Outgoing, class Incoming>
+Incoming Connection<Outgoing, Incoming>::recv( void )
+{
+  struct sockaddr_in packet_remote_addr;
+
+  char buf[ RECEIVE_MTU ];
+
+  socklen_t addrlen = sizeof( packet_remote_addr );
+
+  ssize_t received_len = recvfrom( sock, buf, RECEIVE_MTU, 0, (sockaddr *)&packet_remote_addr, &addrlen );
+
+  if ( received_len < 0 ) {
+    perror( "recvfrom" );
+    exit( 1 );
+  }
+
+  if ( received_len > RECEIVE_MTU ) {
+    fprintf( stderr, "Received oversize datagram (size %d) and limit is %d.\n",
+	     static_cast<int>( received_len ), RECEIVE_MTU );
+    exit( 1 );
+  }
+
+  typename Flow<Incoming>::Packet p( string( buf, received_len ) );
+  dos_assert( p.direction == (server ? TO_SERVER : TO_CLIENT) ); /* prevent malicious playback to sender */
+
+  /* server auto-adjusts to client */
+  if ( server ) {
+    attached = true;
+
+    if ( (remote_addr.sin_addr.s_addr != packet_remote_addr.sin_addr.s_addr)
+	 || (remote_addr.sin_port != packet_remote_addr.sin_port) ) {
+      remote_addr = packet_remote_addr;
+      fprintf( stderr, "Server now attached to client at %s:%d\n",
+	       inet_ntoa( remote_addr.sin_addr ),
+	       ntohs( remote_addr.sin_port ) );
+    }
+  }
+
+  return p.payload;
+}
+
+template <class Outgoing, class Incoming>
+int Connection<Outgoing, Incoming>::port( void )
+{
+  struct sockaddr_in local_addr;
+  socklen_t addrlen = sizeof( local_addr );
+
+  if ( getsockname( sock, (sockaddr *)&local_addr, &addrlen ) < 0 ) {
+    perror( "getsockname" );
+    exit( 1 );
+  }
+
+  return ntohs( local_addr.sin_port );
 }

network.hpp

@@ -7,37 +7,78 @@
 #include <netinet/in.h>
 #include <string>
 
+using namespace std;
+
 namespace Network {
-  template <class Payload>
-  class Connection {
-  private:
-    class Packet {
-    public:
-      int64_t seq;
-      int64_t reference_seq;
-
-      std::string tag;
-
-      int64_t ack;
-
-      Payload state;
-
-      Packet( int64_t s_seq, int64_t s_ack, Packet *s_previous, Payload s_state );
-      Packet( std::string wire );
+  enum Direction {
+    TO_SERVER = 0,
+    TO_CLIENT = 1
   };
 
-    int64_t next_seq;
-    int64_t next_ack;
-    int sequence_increment;
+  template <class Payload>
+  class Flow {
+  public:
+    class Packet {
+    private:
+      class DecodingCache
+      {
+      public:
+	Direction direction;
+	uint64_t seq;
+	string payload_string;
 
-    int sock;
-    struct sockaddr_in addr;
+	DecodingCache( string coded_packet );
+	DecodingCache() : direction( TO_CLIENT ), seq( -1 ), payload_string() {}
+      };
 
-    std::deque<Packet> send_queue;
-    std::deque<Packet> recv_queue;
+      DecodingCache decoding_cache;
 
     public:
-    Connection( const char *ip, const char *port, bool server );
+      uint64_t seq;
+      Direction direction;
+      Payload payload;
+      
+      Packet( uint64_t s_seq, Direction s_direction, Payload s_payload )
+	: decoding_cache(), seq( s_seq ), direction( s_direction ), payload( s_payload )
+      {}
+      
+      Packet( string coded_packet );
+      
+      string tostring( void );
+    };
+
+    uint64_t next_seq;
+    const Direction direction;
+    int MTU;
+
+    Flow( Direction s_direction )
+      : next_seq( 0 ), direction( s_direction ), MTU( 2048 )
+    {}
+
+    Packet new_packet( Payload &s_payload );
+  };
+
+  template <class Outgoing, class Incoming>
+  class Connection {
+  private:
+    static const int RECEIVE_MTU = 2048;
+
+    Flow<Outgoing> flow;
+
+    int sock;
+    struct sockaddr_in remote_addr;
+
+    bool server;
+    bool attached;
+
+  public:
+    Connection( bool s_server );
+    
+    void client_connect( const char *ip, int port );
+    void send( Outgoing &s );
+    Incoming recv( void );
+    int fd( void ) { return sock; }
+    int port( void );
   };
 }
 

ntester.cpp

@@ -1,12 +1,39 @@
 #include "network.hpp"
+#include "keystroke.hpp"
 
-class KeyStroke
+int main( int argc, char *argv[] )
 {
-public:
-  char letter;
-};
+  bool server = true;
+  char *ip;
+  int port;
 
-int main( void )
-{
-  Network::Connection<KeyStroke> n();
+  if ( argc > 1 ) {
+    server = false;
+
+    ip = argv[ 1 ];
+    port = atoi( argv[ 2 ] );
+  }
+
+  Network::Connection<KeyStroke, KeyStroke> n( server );
+  fprintf( stderr, "Port bound is %d\n", n.port() );
+
+  if ( !server ) {
+    n.client_connect( ip, port );
+  }
+
+  if ( server ) {
+    while ( true ) {
+      KeyStroke s = n.recv();
+
+      fprintf( stderr, "Got KeyStroke: %c\n", s.letter );
+    }
+  } else {
+    while( true ) {
+      sleep( 1 );
+
+      KeyStroke t( string( "x", 1 ) );
+
+      n.send( t );
+    }
+  }
 }

templates.cpp

@@ -6,6 +6,9 @@
 
 #include "terminal.hpp"
 
+#include "network.cpp"
+#include "keystroke.hpp"
+
 namespace Parser {
   class Action;
 }
@@ -21,3 +24,4 @@ template class vector<wchar_t>;
 template class vector<int>;
 template class map<string, Function>;
 template class vector<bool>;
+template class Network::Connection<KeyStroke, KeyStroke>;