简介
我正在尝试使用c ++和boost :: asio创建服务器/客户端应用程序，我也尝试使用连续异步读取在另一端接收同步写入。 例如，我的服务器异步读取固定字节长度的数据流，然后移动到客户端同步写入发送的下一个字节。
问题：
在连续异步读取中，第一个流字节被正确读取但是当它继续下一个异步读取时，从另一端发送的东西具有相同的字节长度我正在考虑但是它是垃圾或我无法将其转换为有价值的数据
守则：
private:
static const int MAX_MTU = 1500; //Ethernet Maximum Transfer UNIT (MTU)...
static const int TRASH_CAN = 100; //Amount to substract from the MAX_MTU to make room for basic packet structure elements.
static const int BUFFER_SIZE = MAX_MTU - TRASH_CAN;
boost::mutex mutex;
typedef char* data_bytes;
std::list<data_bytes> data;
private:
tcp::socket socket_;
boost::asio::io_service& io_service_;
moqane::tcp_packet *packet_;
// CTOR for the incoming connection from a client to the server
public: tcp_session(boost::asio::io_service& io_service)
: io_service_(io_service),
socket_(io_service),
packet_(new moqane::tcp_packet())
{
// ......
}
// CTOR for the outgoing clinet connection to the server...
public: tcp_session(boost::asio::io_service& io_service, tcp::resolver::iterator endpoint_iterator)
: io_service_(io_service),
socket_(io_service),
packet_(new moqane::tcp_packet())
{
boost::asio::async_connect(socket_,
endpoint_iterator,
boost::bind(&tcp_session::connect_to_server_hndlr,
this,
boost::asio::placeholders::error)
);
}
tcp::socket& socket()
{
return socket_;
}
public:
void read_header()
{
read_packet(packet_->HEADER_LENGTH,
boost::bind(
&moqane::tcp_session::read_header_hndlr,
shared_from_this(),
packet_->HEADER_LENGTH,
boost::asio::placeholders::error)
);
}
private:
void connect_to_server_hndlr(const boost::system::error_code& error)
{
if (!error)
{
read_header();
}
else
{
// TODO: fire the error event...
}
}
private:
template <class T>
void read_packet(int packet_length, T handler)
{
/*
Packet Structure: (Mohamed Tarek (moqane))
==============================================================================================
HEADER: could be a 3 or 4 bytes that give enough information to the endpoint on how to receive
those bytes.
SIZE : A 4 byte-length number that tell the endpoint how much data in bytes ar comming.
ex: 0340 which should tell us that the incoming data are 340 bytes, so we will not
receive more or less than that.
DATA : the incoming valuable information that we want to receive in the first place.
---------------------------------------------
| | | |
| HEADER | SIZE | DATA... | ----> PACKET
| 3b | 4b | N/A b |
----------------------------------------------
==============================================================================================
*/
if (data.size() > 0)
{
data.clear();
}
char d[moqane::tcp_session::BUFFER_SIZE];
data.push_back(d);
boost::asio::async_read(socket_,
boost::asio::buffer(data.back(), packet_length),
handler
);
}
private:
void write_packet(char* data_bytes)
{
boost::asio::write(socket_, boost::asio::buffer(data_bytes, sizeof(data_bytes)));
}
private:
void write_packet_hndlr(const boost::system::error_code& error)
{
if (!error)
{
}
else
{
}
}
private:
void read_header_hndlr(int packet_length, const boost::system::error_code& error)
{
if (!error)
{
// convert bytes to wxstring
// wxString s = moqane::wx2string::To_wxString(packet_->DATA(), packet_->HEADER_LENGTH());
// convert our bytes to string
std::string header(data.back(), packet_length);
if (packet_->is_header(header))
{
// read the SIZE packet
read_packet(packet_->SIZE_LENGTH,
boost::bind(
&moqane::tcp_session::read_size_hndlr,
shared_from_this(),
packet_->SIZE_LENGTH,
header,
"",
boost::asio::placeholders::error)
);
}
else
{
// reread the HEADER packet if it's not a valid header
read_header();
}
}
else
{
// TODO: fire the error event...
}
}
private:
void read_size_hndlr(int packet_length, std::string header, std::string info, const boost::system::error_code& error)
{
if (!error)
{
std::string str_length(data.back(), packet_length);
int next_packet_length = moqane::number2string::ToInt(str_length);
if (next_packet_length > 0)
{
if (header == packet_->HEADER_STRING)
{
read_packet(next_packet_length,
boost::bind(
&moqane::tcp_session::read_STRING_hndlr,
shared_from_this(),
next_packet_length,
boost::asio::placeholders::error)
);
}
else if (header == packet_->HEADER_COMMAND)
{
}
else
{
// reread the HEADER packet if it's not a valid header
read_header();
}
}
else
{
// reread the HEADER packet if it's not a valid size
read_header();
}
}
else
{
// TODO: fire the error event...
}
}
private:
void read_STRING_hndlr(int packet_length, const boost::system::error_code& error)
{
std::string std_str(data.back(), packet_length);
std::string v = "";
}
public:
void write_STRING(char* string_data)
{
boost::mutex::scoped_lock lock(mutex);
{
write_packet(moqane::number2string::To_CharArray("STR"));
write_packet(moqane::number2string::To_CharArray("xxx1"));
write_packet(moqane::number2string::To_CharArray("a"));
}
}
};
答案 0 :(得分：3)
我怀疑问题出在read_packet
char d[moqane::tcp_session::BUFFER_SIZE];
data.push_back(d);
boost::asio::async_read(socket_,
boost::asio::buffer(data.back(), packet_length),
handler
);
这是在局部变量中创建缓冲区d。然后将指针d推入data，然后用于形成async_read的缓冲区。然后你离开这个功能。这导致数组被破坏，有几个悬空指针，包括async_read。
我建议为标题创建缓冲区，命名类似'header'，作为类的一部分。我不确定您是否需要单独的data向量。
答案 1 :(得分：0)
现在已经解决了，主要问题是在发送时构造缓冲区时出错packet_length。因为我得到了sizeof()的长度，根据我的处理器架构总是返回4。所以我现在使用以下函数得到char *的长度。
public:
static int CharArray_Length(char* somedata)
{
std::list<char> l;
while(*somedata != 0)
l.push_back(*somedata++);
// If you want to add a terminating NULL character
// in your list, uncomment the following statement:
// l.push_back(0);
return l.size();
}