Asio（C++）：从服务器接收数据后无法向服务器发送数据答案

【问题标题】：Asio (C++): Cannot send data to server after receiving data from serverAsio（C++）：从服务器接收数据后无法向服务器发送数据
【发布时间】：2017-01-20 22:27:35
【问题描述】：

我们正在尝试创建一个通过 tcp 套接字对文件进行简单修改的项目。我们使用 Asio 创建了向端口发送和接收数据的类：

//ReceiveData.hpp
#pragma once

#include <string>
#include <thread>
#include <chrono>
#include <vector>
#include <asio.hpp>
#include <iostream>
#include "SendReceiveConsts.hpp" //contains global io service object

using asio::ip::tcp;

typedef unsigned short ushort;

class ReceiveData {
private:
    asio::io_service service;
    tcp::acceptor acceptor;
    tcp::socket socket;
public:
    ReceiveData(ushort port = 8008) : acceptor(SendReceive::global_io_service, tcp::endpoint(tcp::v4(), port)),
                           socket(SendReceive::global_io_service) { }

    // Can return any amount on the socket stream
    template<size_t N>
    inline std::string receive() {
        std::string message;
        try {
            if (!this->socket.is_open()) {
                this->acceptor.accept(socket);
            }

            SendReceive::global_io_service.run();

            std::array<char, N> buf;
            asio::error_code error;
            size_t len = this->socket.read_some(asio::buffer(buf), error);

            if(error)
                throw asio::system_error(error);

            std::copy(buf.begin(), buf.end(), std::back_inserter(message));

        } catch(asio::error_code& e) {
            std::cout << e.message() << std::endl;
            return "-1";
        } catch (std::exception& e) {
            std::cout << e.what() << std::endl;
            return "-1";
        }
        return message;
    }

    inline void stop() {
        asio::error_code error;
        socket.shutdown(tcp::socket::shutdown_type::shutdown_send, error);
    }
};

//SendData.hpp
#pragma once

#ifdef __GNUC__
#define DEPRECATED(func) func __attribute__ ((deprecated))
#elif defined(_MSC_VER)
#define DEPRECATED(func) __declspec(deprecated) func
#else
#pragma message("WARNING: You need to implement DEPRECATED for this compiler")
#define DEPRECATED(func) func
#endif

#include <asio.hpp>
#include <chrono>
#include <vector>
#include <string>
#include <tuple>
#include <iostream>

#include "SendReceiveConsts.hpp"

using asio::ip::tcp;
typedef unsigned short ushort;

class SendData {
private:
    tcp::resolver resolver;
    tcp::resolver::query query;
    tcp::socket socket;
    tcp::resolver::iterator endpoint_iterator;

    std::string IP;
    ushort port;

    inline void send_string(std::string dataToSend, const char &separator = '\0') {
        if(!this->socket.is_open()) {
            asio::connect(this->socket, this->endpoint_iterator);
        }

        SendReceive::global_io_service.run();

        std::string MISTCompliant = dataToSend;
        MISTCompliant.push_back(separator);
        printf("Sent %lu to %s\n", asio::write(socket, asio::buffer(MISTCompliant.c_str(), MISTCompliant.length())), IP.c_str());
    };

public:
    SendData(std::string IP, ushort port)
              : resolver(SendReceive::global_io_service),
                query(IP, std::to_string(port)),
                socket(SendReceive::global_io_service) {
       this->IP = IP;
       this->port = port;
       this->endpoint_iterator = resolver.resolve(this->query);
   }

   ~SendData() { stop(); }

    DEPRECATED(void simple_send(std::string data));

    inline void send(std::string data, const char &separator = '\0') {
        send_string(data, separator);
    }

    inline void stop() {
        asio::error_code error;
        this->socket.shutdown(tcp::socket::shutdown_type::shutdown_receive, error);
        if(error) {
            printf("An error occurred when shutting down SendData socket: %s (File: %s, Line %i)\n", error.message().c_str(), __FILE__, __LINE__);
        }
        this->socket.close();
        printf("Socket closed.\n");
    }

    inline std::tuple<std::string, ushort> get_raw_info() {
        return std::tuple<std::string, ushort>(this->IP, this->port);
    }
};

使用这些类，我们能够从主两台从机发送数据，它们能够可靠地接收数据。但是，主设备永远无法从从设备接收数据。这是在master上运行的代码：

//HashFile.cpp
#include <string>
#include <fstream>
#include <time.h>
#include <thread>
#include <chrono>

#include <networking/SendData.hpp>
#include <networking/ReceiveData.hpp>
#include <MIST.hpp>
#include <Machine.hpp>

#define FILE_SIZE 60

std::string random_salt(std::string s) {
    std::string copy = "";
    std::string chars = "abcdefghijklmnopqrstufwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ12345678910!@#$%^&*()_+-=";
    for(std::string::iterator i = s.begin(); i != s.end(); i++) {
       copy.push_back(*i);
       srand(time(0));
        if((rand() % 100) < 10) {
            srand(time(0));
            copy.push_back(chars.at(rand() % chars.length()));
        }
    }
    return copy;
}

std::string add_salt(std::string s) {
    std::string copy = "";
    for(std::string::iterator i = s.begin(); i != s.end(); i++) {
        copy.push_back(*i);
        if(*i == '6') {
            copy.push_back('w');
            copy.push_back('h');
            copy.push_back('a');
            copy.push_back('t');
        } else if(*i == 'c' && *i == '9' && *i == 'D') { //c9D
            //HG6v
            copy.pop_back();
            copy.push_back(*i);
            copy.push_back('G');
            copy.push_back('6');
            copy.push_back('v');
        } else if(tolower(*i) == 'm' && tolower(*(i + 1)) == 'i') {
            copy.push_back('s');
            copy.push_back('t');
        }
    }
    return copy;
}

int main() {
    std::vector<MIST::Machine> machines_used = { MIST::Machine("local"), MIST::Machine("Helper 1", "25.88.30.47", false), MIST::Machine("Helper 2", "25.88.123.114", false) }; //Hamachi IP addresses
    auto mist = MIST::MIST(true, machines_used);

    std::ifstream hash;
    std::string data1 = "";
    std::string data2 = "";
    std::string mydata = "";
    printf("Dangerously large file being imported into code...\n");
    hash.open("testfile_smol", std::fstream::binary);
    if(hash.is_open()) {
        try {
            char chunk;
            int counter = 0;
            while(hash.get(chunk)) {
               if(counter < FILE_SIZE / 3) {
                    data1 += chunk;
                    counter++;
                } else if(counter < FILE_SIZE * (2.0f / 3.0f)) {
                    data2 += chunk;
                    counter++;
                } else {
                    mydata += chunk;
                    counter++;
                }
            }
        } catch(std::exception& e) {
            std::cerr << "Error encountered: " << e.what() << std::endl;
        }
    }
    hash.close();

    printf("data1: %s data2: %s mydata: %s", data1.substr(0, 10).c_str(), data2.substr(0, 10).c_str(), mydata.substr(0, 10).c_str());

    ProtobufMIST::Task task;
    task.set_task_name("hash");
    std::string serialized;
    task.SerializeToString(&serialized);

    const char c = 185;

    printf("Send all!\n");
    std::string s1 = "1" + data1 + c + serialized;
    std::string s2 = "2" + data2 + c + serialized;

    mist.send_task(s1, "Helper 1", 1025);
    printf("Updated first task!\n");

    mist.send_task(s2, "Helper 2", 1025); //Just a wrapper for SendData, as described in SendData.h
    printf("Updated first task!\n");

    std::string mydata_salted = add_salt(random_salt(mydata)); //TODO: Add pepper

    printf("Old mydata size: %zu\nNew mydata size: %zu\n", mydata.length(), mydata_salted.length());

    std::string one(""), two("");
    unsigned short port1 = 1026;
    unsigned short port2 = 1027;

    auto receive_slaves = [=](unsigned short& port, std::string& out) {
        bool got = false;
        printf("Looking for string on port %u\n", port);
        while(!got) {
            auto slave = new ReceiveData(port); //As defined in ReceiveData.hpp
            std::string x = slave->receive<1>();
            printf("Got chunk: %s\n", x.c_str());
            if(!(x.find((char)182) != std::string::npos || x == "-1")) {
                out += x;
            } else {
                got = true;
            }
            delete slave;
        }
        printf("Received full string!\n");
    };

    printf("Openning both receive channels...\n");
    printf("Waiting for strings...\n");
    //THIS IS WHERE IT BREAKS
    receive_slaves(port2, two); //Never gets response
    receive_slaves(port1, one); //Never gets response
    printf("Received all parts!\n");

    printf("Removing delimiters...\n");
    one.erase(std::remove(one.begin(), one.end(), (char)182), one.end());
    two.erase(std::remove(two.begin(), two.end(), (char)182), two.end());

    std::ofstream output;
    output.open("Hashed");
    output << one << two << mydata_salted;
    output.close();

    printf("Aloha!\n");

    return 0;
}

如您所见，整个文件旨在读取固定大小的文件，将第三个发送到两个从属设备，并用随机字符和其他转换“加盐”最后三分之一。但是，如上所述，程序在接收其他已完成的部分时会卡住。这是奴隶代码的样子

//HashFile.cpp (Slave)
#include <string>
#include <fstream>
#include <thread>
#include <chrono>
#include <time.h>
#include <MIST.pb.h>
#include <networking/SendData.hpp>
#include <networking/ReceiveData.hpp>
#include <MIST.hpp>
#include <Machine.hpp>
#include <stdlib.h>

std::string data;
std::string task;
std::string firstTwoChars;
ProtobufMIST::Task _task;
const char d = 182;
const char d_spc = 185;
int part;
std::string random_salt(std::string s) {
    std::string copy = "";
    std::string chars = "abcdefghijklmnopqrstufwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ12345678910!@#$%^&*()_+-=";
    for (std::string::iterator i = s.begin(); i != s.end(); i++) {
        copy.push_back(*i);
        srand(time(0));
        if ((rand() % 100) < 10) {
            srand(time(0));
            copy.push_back(chars.at(rand() % chars.length()));
        }
    }
    return copy;
}
std::string add_salt(std::string s) {
    std::string copy = "";
    for (std::string::iterator i = s.begin(); i != s.end(); i++) {
        copy.push_back(*i);
        if (*i == '6') {
            copy.push_back('w');
            copy.push_back('h');
            copy.push_back('a');
            copy.push_back('t');
        }
        else if (*i == 'c' && *i == '9' && *i == 'D') { //c9D
            copy.pop_back();
            copy.push_back(*i);
            copy.push_back('G');
            copy.push_back('6');
            copy.push_back('v');
        }
        else if (tolower(*i) == 'm' && tolower(*(i + 1)) == 'i') {
            copy.push_back('s');
            copy.push_back('t');
        }
    }
    return copy;
}
//Previously defined salting functions
void hash()
{
    data = random_salt(data); //randomly salt
    data = add_salt(data); //add random chars
}
int main()
{
    MIST::Task taskThing("hash", *hash);
    ReceiveData * rObj = new ReceiveData(1025);
    SendData sObj("25.88.220.173", 1027);
    std::cout << "Receiving first char \n";
    firstTwoChars = rObj->receive<1>();
    //delete rObj;
    std::cout << firstTwoChars << std::endl;
    std::cout << "Received first char \n";
    int slavePart;
if (firstTwoChars == "1") {
        slavePart = 1;
    }
    else if (firstTwoChars == "2") {
        slavePart = 2;
    }
    else
        std::cout << "You messed up, what part is it? \n";
    std::cout << "Is part " << slavePart << std::endl;

    bool dataRecieved = false;
    while (!dataRecieved)
    {
    std::string chunk = rObj->receive<1>();
        if (chunk == "-1" || chunk.find((char)182) != std::string::npos) {
            std::cout << "Data recieved \n";
            dataRecieved = true;
        }
        else
        {
            data += chunk;
            std::cout << "Added chunk: " << chunk << std::endl;
        }
        chunk.clear();
    }
    std::cout << "All Data recieved! \n Parsing now \n";

    if (data.find(d_spc) != std::string::npos)
    {
        size_t data_before = data.find(d_spc); //find where data ends and task begins
        std::cout << "Data found at " << data_before << "bytes. \n";
        std::string task = data.substr(data_before); //copy task to new string
        std::cout << "Task copied: " << task << std::endl;
        data.erase(data_before);//erase everything that was the task from it's original string
    }
    else {
        std::cout << "Did not find d_spc \n";
        std::abort();
    }
    std::cout << "Data parsed \n Data: \n";
    std::cout << data << std::endl;
    std::cout << "Task: " << task << std::endl;

    if (_task.ParseFromString(task))
    {
        std::cout << "Task parsed properly \n";
    }
    else {
        std::cout << "I messed up parsing, trying again \n";
        if (_task.ParseFromString(task)) {
            task.pop_back();
            std::cout << "Worked the second time! \n";
        }
        else {
            std::cout << "Still messed up \n";
            std::abort();
        }
    }
    if(_task.task_name() == "hash")
        taskThing.run();
    std::cout << taskThing.getID();
    std::cout << "Sending... \n";
    std::this_thread::sleep_for(std::chrono::milliseconds(500));
    std::string t_str = std::to_string(slavePart) + data;

    //THIS IS WHERE IT BREAKS
    sObj.send(t_str, d); //error

    int x;
    std::cin >> x;
    std::cout << "Sent! \n";
}

这是尝试重新连接到主服务器时出现的错误：

connect：连接尝试失败，因为连接方成功了一段时间后没有正确响应，或建立连接失败，因为主机没有响应。:connect: 一个连接尝试失败，因为连接方没有正确响应一段时间后，或建立的连接失败，因为主机没有响应。

从我们所处的位置来看，这没有任何意义，因为在 master 上运行了一个监听进程。我们感觉这与我们在发送和接收类中包装 Asio 的方式有关，但我们不确定在哪里。

作为参考，这是一个跨平台项目。主服务器在 Ubuntu 16.10 上运行，两个从服务器在 Windows 10 上运行。我们禁用了防火墙并在 Hamachi 上运行项目。另请注意，每个从属设备都在自己的端口上发送完成的字符串部分。

【问题讨论】：

标签： sockets c++14 boost-asio winsock

【解决方案1】：

看起来您在从程序上创建 SendData 之前，另一端有可用的套接字，导致解析器（在您创建 SendData 对象时运行）无法解析您使用的 IP 地址。尝试在发送数据之前创建 SendData。

另外，ASIO 的包装很好。它可能需要一些工作，但它只是一个开始，它似乎比直接使用 ASIO 更简单。

【讨论】：