Linux网络 - json，网络计算服务器与客户端改进

前言

本章内容主要对上一章的网络计算器客户端和服务器进行一些Bug修正与功能改进。 并学习如何使用json库和daemon函数。

一、json

在我们自己的电脑上一些软件的文件夹中，我们经常能看到.json后缀的文件，那么这种文件是用来干什么的呢？

这就要说到我们上节课所讲的序列化和反序列化了，相信如果大家自己如果尝试写了一遍之后，会发现序列化和反序列化还是比较难写的。

而市面上，是存在这么一个库被广泛引用来做序列化和反序列化，他就是json库。

json库是一个第三方库，所以我们的Linux服务器一般是不自带的，需要下载安装。

sudo yum install -y jsoncpp-devel

安装后，它的头文件位于

ls /usr/include/jsoncpp/json

因为是第三方库，所以它也需要链接动态库。

ls /lib64/libjsoncpp.so

1.引入库

代码如下（示例）：

#include <jsoncpp/json/json.h>

g++编译

Lib=-ljsoncpp
serverCal:main.cc
	g++ -o $@ $^ -std=c++11 -lpthread $(Lib)

clientCal:clientCal.cc
	g++ -o $@ $^ -std=c++11 $(Lib)

2. 使用步骤

#pragma once
#include <iostream>
#include <string>
#include "log.hpp"
#include <jsoncpp/json/json.h>

extern Log lg;
const char blank_space_sep = ' ';
const char protocol_sep = '\n';

enum Code
{
    Div_Zero_Err = 1,
    Mod_Zeor_Err,
    Operatorr_Err,
    Float_Mod_Err
};

enum Type
{
    Type_Int = 1,
    Type_Double = 2
};

// 多态版本

bool CheckType(std::string &in_str, int* type)
{
    Json::Value root;
    Json::Reader reader;
    bool suc = reader.parse(in_str, root);
    if (!suc)
    {
        lg(Warning, "Deserialize Failed...");
        return false;
    }
    *type = root["type"].asInt();
    return true;
}

class Request
{
public:
    Request() {}
    Request(char op)
        : _op(op) {}

    virtual bool serialize() {}

    virtual bool deserialize() {}

public:
    char _op;
};

class IntRequest : public Request
{
public:
    IntRequest() {}
    IntRequest(int x, int y, char op)
        : _x(x), _y(y), Request(op) {}

    virtual bool serialize(std::string *out_str)
    {
        Json::Value root;
        root["x"] = _x;
        root["y"] = _y;
        root["op"] = _op;
        root["type"] = 1;
        Json::FastWriter writer;
        *out_str = writer.write(root);
        return true;
    }

    virtual bool deserialize(std::string &in_str)
    {
        Json::Value root;
        Json::Reader reader;
        bool suc = reader.parse(in_str, root);
        if (!suc)
        {
            lg(Warning, "Request Deserialize Failed...");
            return false;
        }
        _x = root["x"].asInt();
        _y = root["y"].asInt();
        _op = root["op"].asInt();
        Json::FastWriter writer;
        in_str.erase(0, writer.write(root).size());
        std::cout << "已经删除已解析报头..." << std::endl;
        return true;
    }

public:
    int _x;
    int _y;
};

class DoubleRequest : public Request
{
public:
    DoubleRequest() {}
    DoubleRequest(double x, double y, char op)
        : _x(x), _y(y), Request(op) {}

    virtual bool serialize(std::string *out_str)
    {
        Json::Value root;
        root["x"] = _x;
        root["y"] = _y;
        root["op"] = _op;
        root["type"] = 2;
        Json::FastWriter writer;
        *out_str = writer.write(root);
        return true;
    }

    virtual bool deserialize(std::string &in_str)
    {
        Json::Value root;
        Json::Reader reader;
        bool suc = reader.parse(in_str, root);
        if (!suc)
        {
            lg(Warning, "Request Deserialize Failed...");
            return false;
        }
        _x = root["x"].asDouble();
        _y = root["y"].asDouble();
        _op = root["op"].asInt();
        Json::FastWriter writer;
        in_str.erase(0, writer.write(root).size());
        return true;
    }

public:
    double _x;
    double _y;
};

class Respond
{
public:
    Respond() {}
    Respond(int code)
        : _code(code) {}

    virtual bool serialize() {}

    virtual bool deserialize() {}

public:
    int _code = -1;
};

class IntRespond : public Respond
{
public:
    IntRespond() {}
    IntRespond(int result, int code)
        : _result(result), Respond(code) {}

    virtual bool serialize(std::string *out_str)
    {

        Json::Value root;
        root["result"] = _result;
        root["code"] = _code;
        root["type"] = 1;
        Json::FastWriter writer;
        *out_str = writer.write(root);
        return true;
    }

    virtual bool deserialize(const std::string &in_str)
    {
        Json::Value root;
        Json::Reader reader;
        bool suc = reader.parse(in_str, root);
        if (!suc)
        {
            lg(Warning, "Respond Deserialize Failed...");
            return false;
        }
        _result = root["result"].asInt();
        _code = root["code"].asInt();
        return true;
    }

public:
    int _result;
};

class DoubleRespond : public Respond
{
public:
    DoubleRespond() {}
    DoubleRespond(double result, int code)
        : _result(result), Respond(code) {}

    virtual bool serialize(std::string *out_str)
    {

        Json::Value root;
        root["result"] = _result;
        root["code"] = _code;
        root["type"] = 2;
        Json::FastWriter writer;
        *out_str = writer.write(root);
        return true;
    }

    virtual bool deserialize(const std::string &in_str)
    {
        Json::Value root;
        Json::Reader reader;
        bool suc = reader.parse(in_str, root);
        if (!suc)
        {
            lg(Warning, "Respond Deserialize Failed...");
            return false;
        }
        _result = root["result"].asDouble();
        _code = root["code"].asInt();
        return true;
    }

public:
    double _result;
};

2.Calculator.hpp

#pragma once
#include "protocol.hpp"

class Calculator
{
public:
    Calculator() {}
    IntRespond calculate(const IntRequest &rq)
    {
        IntRespond rs;
        switch (rq._op)
        {
        case '+':
            rs._result = rq._x + rq._y;
            break;
        case '-':
            rs._result = rq._x - rq._y;
            break;
        case '*':
            rs._result = rq._x * rq._y;
            break;
        case '/':
            if (rq._y == 0)
            {
                lg(Warning, "Found Div Zero Error...");
                rs._code = Div_Zero_Err;
                return rs;
            }
            rs._result = rq._x / rq._y;
            break;
        case '%':
            if (rq._y == 0)
            {
                lg(Warning, "Found Mod Zero Error...");
                rs._code = Mod_Zeor_Err;
                return rs;
            }
            rs._result = rq._x % rq._y;
            break;

        default:
            lg(Warning, "Found Operator Error...");
            rs._code = Operatorr_Err;
            return rs;
        }
        rs._code = 0;
        return rs;
    }

    DoubleRespond calculate(const DoubleRequest &rq)
    {
        DoubleRespond rs;
        switch (rq._op)
        {
        case '+':
            rs._result = rq._x + rq._y;
            break;
        case '-':
            rs._result = rq._x - rq._y;
            break;
        case '*':
            rs._result = rq._x * rq._y;
            break;
        case '/':
            if (rq._y == 0)
            {
                lg(Warning, "Found Div Zero Error...");
                rs._code = Div_Zero_Err;
                return rs;
            }
            rs._result = rq._x / rq._y;
            break;
        case '%':
            lg(Warning, "Float Mod Error...");
            rs._code = Float_Mod_Err;
            return rs;

        default:
            lg(Warning, "Found Operator Error...");
            rs._code = Operatorr_Err;
            return rs;
        }
        rs._code = 0;
        return rs;
    }
};

3.Task.hpp

#pragma once
#include "Socket.hpp"
#include "protocol.hpp"
#include "Calculator.hpp"
class Task
{
public:
    Task(int socket_fd)
        : _socket_fd(socket_fd)
    {
    }
    
    void IntHandle(std::string &message)
    {
        IntRequest rq;
        Calculator cal;
        // 因为可能message里面已经存在了多个报文，所以就需要一次性多次处理
        if (!rq.deserialize(message))
        {
            // 反序列化失败说明里面的数据可能出现数据丢失等情况，出现这种情况说明我们的报文数据不再可信，最直接的办法就是丢弃全部报文！
            message = "";
            return;
        }
        IntRespond rs = cal.calculate(rq);
        std::string res;
        rs.serialize(&res);
        printf("%d %c %d = %d\n", rq._x, rq._op, rq._y, rs._result);
        write(_socket_fd, res.c_str(), res.size());
    }

    void DoubleHandle(std::string &message)
    {
        DoubleRequest rq;
        Calculator cal;
        // 因为可能message里面已经存在了多个报文，所以就需要一次性多次处理
        if (!rq.deserialize(message))
        {
            // 反序列化失败说明里面的数据可能出现数据丢失等情况，出现这种情况说明我们的报文数据不再可信，最直接的办法就是丢弃全部报文！
            message = "";
            return;
        }
        DoubleRespond rs = cal.calculate(rq);
        std::string res;
        rs.serialize(&res);
        printf("%lf %c %lf = %lf\n", rq._x, rq._op, rq._y, rs._result);
        write(_socket_fd, res.c_str(), res.size());
    }

    void run()
    {
        char in_buffer[1024];
        std::string message = "";
        while (true)
        {
            memset(in_buffer, 0, sizeof in_buffer);
            int n = read(_socket_fd, (void *)in_buffer, sizeof in_buffer - 1);
            if (n == 0)
            {
                lg(Warning, "Connection closed by foreign host, socketfd[%d] closed...", _socket_fd);
                break;
            }
            else if (n < 0)
            {
                lg(Warning, "Read Error, socketfd[%d]...", _socket_fd);
                break;
            }
            in_buffer[n] = 0;
            message = in_buffer;
            std::cout << "报文大小: " << message.size() << " ,报文内容: " << message << std::endl;

            // 判断发来的数据类型

            while (!message.empty())
            {
                int type;
                if (!CheckType(message, &type))
                {
                    //报文内容出现问题
                    message = "";
                    break;
                }
                if (type == 1)
                {
                    IntHandle(message);
                }
                else if (type == 2)
                {
                    DoubleHandle(message);
                }
                else{
                    lg(Warning, "Type Error, type: %d ...", type);
                }
            }
        }
    }

    void operator()()
    {
        run();
        close(_socket_fd);
    }

    ~Task()
    {
    }

private:
    int _socket_fd;
};

4.serverCal.hpp

#pragma once

#include "Socket.hpp"
#include "protocol.hpp"
#include "threadPool.hpp"
#include "Task.hpp"
class ServerCal
{
public:
    ServerCal()
    {
    }

    void Init(const int sinfamily, const std::string &ip, const uint16_t port)
    {
        _listensock.Init();
        _listensock.Bind(sinfamily, ip, port);
        _listensock.Listen();
    }

    void Run()
    {
        daemon(0, 0);  //仅此这里添加了一个守护线程功能
        ThreadPool<Task> *tp = ThreadPool<Task>::GetInstance();
        tp->Start();
        struct sockaddr_in client;

        while (true)
        {
            memset(&client, 0, sizeof client);
            socklen_t len;
            int socketfd = _listensock.Accept(&client, &len);
            if (socketfd < 0)
                continue;
            tp->Push(socketfd);

        }
    }

private:
    Socket _listensock;
};

这里我添加了守护线程的功能，使用的是系统库自带的函数。

nochdir如果被设为0，则更改工作路径为“/”根目录，否则则什么也不敢。
noclose如果被设为0，则将标准输入输出错误重定向到/dev/null文件中，/dev/null文件我们上章是讲过的。

其他的文件我没有变动，需要的可以在我上一个文章复制粘贴或者到我的gitee自行拷贝。

新客户端

#include "Socket.hpp"
#include "protocol.hpp"

#define VALID_OP 5
const char valid_operator[VALID_OP] = {'+', '-', '*', '/', '%'};

static int localfd = -1;

void Usage(const char *mes)
{
    std::cout << "Usage: " << mes << " ip[xxx.xxx.xxx.xxx] port[8080-9000]" << std::endl;
}

bool __CheckNumber(const std::string &str)
{
    for (const char c : str)
    {
        if ((!isdigit(c)) && (c != '.'))
        {
            return false;
        }
    }
    return true;
}

bool __CheckOp(const std::string &op)
{
    if (op.size() != 1)
    {
        return false;
    }

    for (int i = 0; i < VALID_OP; i++)
    {
        if (op.find(valid_operator[i]) != std::string::npos)
            break;
        if (i == 4)
        {
            return false;
        }
    }
    return true;
}

bool CheckSafe(const std::string &x, const std::string &op, const std::string &y, int *type)
{

    if (!__CheckOp(op))
    {
        std::cout << "Helper: 使用了除 + - * / % 以外的运算符" << std::endl;
        return false;
    }

    if (!__CheckNumber(x) || !__CheckNumber(y))
    {
        std::cout << "Helper: 请输入正确的数字" << std::endl;
        return false;
    }

    if ((x.find('.') != std::string::npos) || (y.find('.') != std::string::npos))
    {
        // 说明这是浮点数运算
        *type = 2;
        return true;
    }
    *type = 1;
    return true;
}

void IntHandle(const std::string &x, const std::string &op, const std::string &y, std::string &message)
{
    IntRequest rq;
    IntRespond rs;

    rq._x = std::stoi(x);
    rq._y = std::stoi(y);
    rq._op = op[0];

    rq.serialize(&message);
    write(localfd, message.c_str(), message.size());

    // 开始等待结果
    char buffer[1024];
    int n = read(localfd, buffer, sizeof buffer - 1);
    if (n == 0)
    {
        lg(Warning, "Connection closed by foreign host, socketfd[%d] closed...", localfd);
        exit(1);
    }
    else if (n < 0)
    {
        lg(Warning, "Read Error, socketfd[%d]...", localfd);
        exit(2);
    }
    buffer[n] = 0;
    std::string res = buffer;
    std::cout << res << std::endl;
    rs.deserialize(res);
    if (rs._code != 0)
    {
        switch (rs._code)
        {
        case 1:
            std::cout << "出现除0错误" << std::endl;
            break;
        case 2:
            std::cout << "出现模0错误" << std::endl;
            break;
        case 3:
            std::cout << "使用了除 + - * / % 以外的运算符" << std::endl;
            break;
        default:
            std::cout << "发生未知错误" << std::endl;
            break;
        }
        return;
    }
    printf("%d %c %d = %d\n", rq._x, rq._op, rq._y, rs._result);
}

void DoubleHandle(const std::string &x, const std::string &op, const std::string &y, std::string &message)
{
    DoubleRequest rq;
    DoubleRespond rs;

    rq._x = std::stod(x);
    rq._y = std::stod(y);
    rq._op = op[0];

    rq.serialize(&message);
    write(localfd, message.c_str(), message.size());

    // 开始等待结果
    char buffer[1024];
    int n = read(localfd, buffer, sizeof buffer - 1);
    if (n == 0)
    {
        lg(Warning, "Connection closed by foreign host, socketfd[%d] closed...", localfd);
        exit(1);
    }
    else if (n < 0)
    {
        lg(Warning, "Read Error, socketfd[%d]...", localfd);
        exit(2);
    }
    buffer[n] = 0;
    std::string res = buffer;
    std::cout << res << std::endl;
    rs.deserialize(res);
    if (rs._code != 0)
    {
        switch (rs._code)
        {
        case 1:
            std::cout << "出现除0错误" << std::endl;
            break;
        case 2:
            std::cout << "出现模0错误" << std::endl;
            break;
        case 3:
            std::cout << "使用了除 + - * / % 以外的运算符" << std::endl;
            break;
        default:
            std::cout << "发生未知错误" << std::endl;
            break;
        }
        return;
    }
    printf("%lf %c %lf = %lf\n", rq._x, rq._op, rq._y, rs._result);
}

int main(int argc, char *argv[])
{
    if (argc != 3)
    {
        Usage("./clientCal");
    }
    Socket local;
    local.Init();
    int n = local.Connect(argv[1], argv[2]);
    if (n < 0)
    {
        return 1;
    }

    localfd = local.Getfd();

    std::cout << "            简易计算器, 目前仅支持\" + - * / %\"运算符 " << std::endl;
    std::cout << "            数字和运算符请用空格或回车隔开" << std::endl;
    std::string x, op, y;
    int type;
    std::string message;
    while (true)
    {
        std::cout << "请输入您的算式@ ";
        std::cin >> x >> op >> y;
        if (!CheckSafe(x, op, y, &type))
        {
            continue;
        }
        std::cout << type << std::endl;
        if (type == 1)
        {
            IntHandle(x,op,y,message);
        }
        else if(type ==2)
        {
            DoubleHandle(x,op,y,message);
        }
        else{
            lg(Warning, "Type Error, type: %d ...", type);
            exit(3);
        }
    }
    return 0;
}

添加了许多输入的安全检查，不检查引发的问题太多了！