Boost.Asio: Reading input from SSL-Socket results in incomplete data

问题

I have a class called NIUserSession which handles a SSL-encrypted connection with a client. This is it, although I removed everything which is not relevant for my question:

typedef boost::asio::ssl::stream<boost::asio::ip::tcp::socket> ssl_socket;


class NIUserSession
{
public:

    /*....*/
    void readUntil(std::string until);
    /*....*/

private:

    /*....*/
    void readHandler(const boost::system::error_code& error, std::size_t bytes_transferred);
    ssl_socket socket_;
    boost::asio::streambuf readBuffer;
    /*....*/

};

void NIUserSession::readUntil(std::string until)
{
    boost::asio::async_read_until(this->socket_, this->readBuffer, until, boost::bind(&NIUserSession::readHandler,
                                                                                      this,
                                                                                      boost::asio::placeholders::error(),
                                                                                      boost::asio::placeholders::bytes_transferred()));
}

void NIUserSession::readHandler(const boost::system::error_code &error, std::size_t bytes_transferred)
{
    if(!error)
    {
        std::cout << "Bytes transfered: " << bytes_transferred << std::endl;
        this->readBuffer.commit(bytes_transferred);
        std::istream istrm(&this->readBuffer);
        std::string message;
        istrm >> message;

        std::cout << "Message: " << message << std::endl;
    } else {
        // ...
    }
}

Now a client connects, ssl handshake, etc., and then this line is executed from within NIUserSession:

this->readUntil("<EOF>");

The server should now wait until the client sends a message and ends it with <EOF>.

From my client application, I send the following (JSON) data:

The server outputs:

Bytes transfered: 169
Message: {

As you can see, 169 bytes are transfered but only 1 character appears in the output. I think I am doing something wrong with the boost::asio::streambuf (I never used it before).

回答1:

This line:

istrm >> message;

reads a string delimited by whitespace from the stream. That first "{" is a string delimited by whitespace. You just need to keep reading from istrm.

Instead of using operator>>, you can copy the indicated number of bytes to a string by using boost::asio::buffers_begin() to get a random access iterator, and then constructing the string with two iterators. That would look something like this (untested):

const auto bufferIterator = boost::asio::buffers_begin(this->readBuffer.data());
const std::string message(bufferIterator, bufferIterator + bytes_transferred);
this->readBuffer.consume(bytes_transferred);

来源：https://stackoverflow.com/questions/38028766/boost-asio-reading-input-from-ssl-socket-results-in-incomplete-data

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c++

boost

boost-asio