我正在尝试创建一个与现有聊天客户端进行通信的TCP聊天服务器。我无法访问现有聊天客户端的代码，但我知道它通过网络发送的内容以及我应该发回的内容。
我正在尝试使用boost::asio库，但出于某种原因，它不想执行第二个boost::asio::async_read而我无法终身解决它。
我编辑了boost::asio::async_read函数以添加printf( "async_read\n" );，只是为了查看它是否实际被调用，确实是。
以下是我输出的内容：
[INFO] Adding Server 0.0.0.0:10013
[INFO] Starting Servers
[ROOM] Client Joined (#1)
async_read
[HEADER] \x70
[HEADER] 112
async_read
[ROOM] Client Left (#1)
客户端紧接着发送两个数据包：
Packet 1 (Header : Body Size):
00000000 70 00 p.
Packet 2 (Body : Auth Info):
00000002 00 0c 59 38 3d 00 38 34 62 63 34 35 62 65 35 66 ..Y8=.84 bc45be5f
00000012 36 33 34 34 35 66 63 33 38 32 34 32 31 61 39 39 63445fc3 82421a99
00000022 31 66 37 66 39 62 00 31 30 35 2e 32 33 36 2e 33 1f7f9b.1 05.236.3
00000032 35 2e 39 39 00 61 39 33 35 66 65 62 32 64 62 66 5.99.a93 5feb2dbf
00000042 36 65 38 66 32 39 30 62 32 61 36 64 36 37 61 35 6e8f290b 2a6d67a5
00000052 31 36 63 65 65 30 36 34 64 38 64 63 37 00 28 00 16cee064 d8dc7.(.
00000062 00 00 81 06 01 00 77 61 63 00 03 00 09 00 00 00 ......wa c.......
如您所见，服务器代码仅接收第一个数据包，然后在第二个boost::asio::async_read调用中停止
以下是修改后的代码：
typedef std::deque< ChatMessage > ChatMessageQueue;
class ChatParticipant
{
public:
virtual ~ChatParticipant( ) { }
virtual void Deliver( const ChatMessage &Message ) = 0;
};
typedef boost::shared_ptr< ChatParticipant > ChatParticipantPtr;
class ChatRoom
{
public:
void join( ChatParticipantPtr Participant )
{
m_Participants.insert( Participant );
printf( "[ROOM] Client Joined (#%i)\n", m_Participants.size( ) );
std::for_each( m_RecentMessages.begin( ), m_RecentMessages.end( ),
boost::bind( &ChatParticipant::Deliver, Participant, _1 ) );
}
void leave( ChatParticipantPtr Participant )
{
printf( "[ROOM] Client Left (#%i)\n", m_Participants.count( Participant ) );
m_Participants.erase( Participant );
}
void deliver( const ChatMessage &Message )
{
m_RecentMessages.push_back( Message );
while( m_RecentMessages.size( ) > MaxRecentMessages )
m_RecentMessages.pop_front( );
std::for_each( m_Participants.begin( ), m_Participants.end( ),
boost::bind( &ChatParticipant::Deliver, _1, boost::ref( Message ) ) );
}
private:
std::set< ChatParticipantPtr > m_Participants;
enum { MaxRecentMessages = 100 };
ChatMessageQueue m_RecentMessages;
};
class ChatSession : public ChatParticipant, public boost::enable_shared_from_this< ChatSession >
{
public:
ChatSession( boost::asio::io_service &IOService, ChatRoom &Room ) : m_Socket( IOService ), m_Room( Room )
{
}
tcp::socket &Socket( )
{
return m_Socket;
}
void Start( )
{
m_Room.join( shared_from_this( ) );
boost::asio::async_read( m_Socket,
boost::asio::buffer( m_ReadMessage.data( ), ChatMessage::HeaderLength ),
boost::bind( &ChatSession::Handle_ReadHeader, shared_from_this( ), boost::asio::placeholders::error ) );
}
void Deliver( const ChatMessage &Message )
{
bool write_in_progress = !m_WriteMessages.empty( );
m_WriteMessages.push_back( Message );
if( !write_in_progress )
{
boost::asio::async_write( m_Socket,
boost::asio::buffer( m_WriteMessages.front( ).data( ), m_WriteMessages.front( ).length( ) ),
boost::bind( &ChatSession::Handle_Write, shared_from_this( ), boost::asio::placeholders::error ) );
}
}
void Handle_ReadHeader( const boost::system::error_code &Error )
{
if( Error )
{
m_Room.leave( shared_from_this( ) );
return;
}
if( m_ReadMessage.DecodeHeader( ) )
{
printf( "[HEADER] %s\n", Strings::StringToHex( m_ReadMessage.data( ) ).c_str( ) );
printf( "[HEADER] %i\n", m_ReadMessage.length( ) );
boost::asio::async_read( m_Socket,
boost::asio::buffer( m_ReadMessage.body( ), m_ReadMessage.length( ) ),
boost::bind( &ChatSession::Handle_ReadBody, shared_from_this( ), boost::asio::placeholders::error ) );
}
}
void Handle_ReadBody( const boost::system::error_code &Error )
{
if( Error )
{
m_Room.leave( shared_from_this( ) );
return;
}
printf( "[BODY] %s\n", Strings::StringToHex( m_ReadMessage.body( ) ).c_str( ) );
//m_Room.deliver( m_ReadMessage );
boost::asio::async_read( m_Socket,
boost::asio::buffer( m_ReadMessage.data( ), ChatMessage::HeaderLength ),
boost::bind( &ChatSession::Handle_ReadHeader, shared_from_this( ), boost::asio::placeholders::error ) );
}
void Handle_Write( const boost::system::error_code &Error )
{
if( Error )
{
m_Room.leave( shared_from_this( ) );
return;
}
m_WriteMessages.pop_front( );
if( !m_WriteMessages.empty( ) )
{
boost::asio::async_write( m_Socket,
boost::asio::buffer( m_WriteMessages.front( ).data( ), m_WriteMessages.front( ).length( ) ),
boost::bind( &ChatSession::Handle_Write, shared_from_this( ), boost::asio::placeholders::error ) );
}
}
private:
tcp::socket m_Socket;
ChatRoom &m_Room;
ChatMessage m_ReadMessage;
ChatMessageQueue m_WriteMessages;
};
typedef boost::shared_ptr< ChatSession > ChatSessionPtr;
class ChatServer
{
public:
ChatServer( boost::asio::io_service &IOService, const tcp::endpoint &EndPoint ) : m_IOService( IOService ), m_Acceptor( IOService, EndPoint )
{
StartAccepting( );
}
void StartAccepting()
{
ChatSessionPtr NewSession( new ChatSession( m_IOService, m_Room ) );
m_Acceptor.async_accept( NewSession->Socket( ),
boost::bind( &ChatServer::Handle_Accept, this, NewSession, boost::asio::placeholders::error ) );
}
void Handle_Accept( ChatSessionPtr Session, const boost::system::error_code& Error )
{
if( !Error )
Session->Start( );
StartAccepting( );
}
private:
boost::asio::io_service &m_IOService;
tcp::acceptor m_Acceptor;
ChatRoom m_Room;
};
typedef boost::shared_ptr< ChatServer > ChatServerPtr;
int main( int argc, char **argv, char **envp )
{
boost::asio::io_service IOService;
tcp::endpoint EndPoint( tcp::v4( ), 10013 );
ChatServerPtr Server( new ChatServer( IOService, EndPoint ) );
printf( "[INFO] Adding Server %s:%i\n", EndPoint.address( ).to_string( ).c_str( ), EndPoint.port( ) );
IOService.run( );
return TRUE;
}
你能看出我做错了吗？
答案 0 :(得分：0)
TCP是面向字节的流，并且在API中没有“数据包”的概念。您的第一次读取是读取112个字节（根据您的调试输出），因此您只需一次调用即可读取标题和正文。
您应该做的是首先通过使用双字节缓冲区调用async_read来读取两个字节的长度。当它返回时，您应解码它并使用该长度指定您想要为正文读取的字节数。这应该是您在下一次调用async_read时将缓冲区参数传递的字节数。