---

前言

我们需要实现一个服务器版的加法器. 我们需要客户端把要计算的两个加数发过去, 然后由服务器进行计算, 最后再把结果返回给客户端`

一、 服务端

1.ServerCal.cc（服务器主文件）

 #include "TcpServer.hpp"
#include "ServerCal.hpp"
#include <unistd.h>
#include "Daemon.hpp"


using namespace std;
static void Usage(const string &proc){
    cout<<"\nUsage: "<<proc<<" port\n"<<endl;
}

int main(int argc,char*argv[]){
    if(argc!=2){
        Usage(argv[0]);
        exit(0);
    }
    uint16_t port=stoi(argv[1]);
    ServerCal cal;
    TcpServer*tsvp=new TcpServer(port,bind(&ServerCal::Calculator,&cal,placeholders::_1));
    //绑定服务器的回调函数
    tsvp->InitServer();//初始化服务器
    Daemon();//守护进程化
    tsvp->Start();//启动

    return 0;
}

2.ServerCal.hpp

#pragma once
#include <iostream>
#include "Protocol.hpp"

enum
{
    Div_Zero = 1,
    Mod_Zero,
    Other_Oper
};

class ServerCal
{
public:
    ServerCal()
    {
    }
    Response CalculatorHelper(const Request &req)
    {
        Response resp(0, 0);
        switch (req.op)
        {
        case '+':
            resp.result = req.x + req.y;
            break;
        case '-':
            resp.result = req.x - req.y;
            break;
        case '*':
            resp.result = req.x * req.y;
            break;
        case '/':
        {
            if (req.y == 0)
                resp.code = Div_Zero;
            else
                resp.result = req.x / req.y;
        }
        break;
        case '%':
        {
            if (req.y == 0)
                resp.code = Mod_Zero;
            else
                resp.result = req.x % req.y;
        }
        break;
        default:
            resp.code = Other_Oper;
            break;
        }

        return resp;
    }


    // 传入的package形式："len"\n"10 + 20"\n
    std::string Calculator(std::string &package)
    {
        std::string content;
        //Decode：去掉字符大小len和\n
        bool r = Decode(package, &content); 
        // "len"\n"10 + 20"\n
        if (!r)
            return "";
        // Decode后："10 + 20"

        Request req;
        r = req.Deserialize(content); 
        // 反序列化过程："10 + 20" ->x=10 op=+ y=20
        if (!r)
            return "";

        content = "";                        
        //进行计算  
        Response resp = CalculatorHelper(req); // result=30 code=0;

        //result与code进行序列化放入content
        resp.Serialize(&content);  // "30 0"
        
        //Encode：序列化后加上len与\n
        content = Encode(content); // "len"\n"30 0"

        return content;
    }
    ~ServerCal()
    {
    }
};

3.Sock.hpp(套接字封装)

#pragma once

#include <iostream>
#include <string>
#include <unistd.h>
#include <cstring>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include "Log.hpp"

enum
{
    SocketErr = 2,
    BindErr,
    ListenErr
};

const int backlog = 10;

class Sock
{
public:
    Sock() {}
    ~Sock()
    {
    }

public:
    void Socket()
    {
        sockfd_ = socket(AF_INET, SOCK_STREAM, 0);
        if (sockfd_ < 0)
        {
            lg(Fatal, "socker error,%s: %d", strerror(errno), errno);
            exit(SocketErr);
        }
    }

    void Bind(uint16_t port)
    {
        struct sockaddr_in local;
        memset(&local, 0, sizeof(local));
        local.sin_family = AF_INET;
        local.sin_port = htons(port);
        local.sin_addr.s_addr = INADDR_ANY;

        if (bind(sockfd_, (struct sockaddr *)&local, sizeof(local)) < 0)
        {
            lg(Fatal, "bind error ,%s: %d", strerror(errno), errno);
            exit(BindErr);
        }

         
    }

    void Listen()
    {
        if (listen(sockfd_, backlog) < 0)
        {
            lg(Fatal, "listen error,%s: %d", strerror(errno), errno);
            exit(ListenErr);
        }
    }

    int Accept(string *clientip, uint16_t *clientport)
    {
        struct sockaddr_in peer;
        socklen_t len = sizeof(peer);
        int newfd = accept(sockfd_, (struct sockaddr *)&peer, &len);
        if (newfd < 0)
        {
            lg(Warning, "accept error,%s: %d", strerror(errno), errno);
            return -1;
        }
        char ipstr[64];
        inet_ntop(AF_INET, &peer.sin_addr, ipstr, sizeof(ipstr));
        *clientip = ipstr;
        *clientport = ntohs(peer.sin_port);

        return newfd;
    }

    bool Connect(const string &ip, const uint16_t port)
    {
        struct sockaddr_in peer;
        memset(&peer, 0, sizeof(peer));
        peer.sin_family = AF_INET;
        peer.sin_port = htons(port);
        inet_pton(AF_INET, ip.c_str(), &(peer.sin_addr));

        int n = connect(sockfd_, (struct sockaddr *)&peer, sizeof(peer));
        if (n == -1)
        {
            std::cerr << "connect to " << ip << ":" << port << " error" << std::endl;
            return false;
        }
        return true;
    }

    void Close()
    {
        close(sockfd_);
    }

    int Fd()
    {
        return sockfd_;
    }

private:
    int sockfd_;
};

4.TcpServer.hpp(服务器)

#pragma once
#include <functional>
#include <string>
#include <signal.h>
#include "Log.hpp"
#include "Socket.hpp"

using func_t = std::function<std::string(std::string &package)>;

class TcpServer
{
public:
    TcpServer(uint16_t port, func_t callback) : port_(port), callback_(callback)
    {
    }
    bool InitServer()
    {
        listensock_.Socket();
        listensock_.Bind(port_);
        listensock_.Listen();
        lg(Info, "init server .... done");
        return true;
    }


    void Start()
    {
        signal(SIGCHLD, SIG_IGN);
        //防止子进程僵尸，子进程执行完PCB自动释放
        signal(SIGPIPE, SIG_IGN);
        //程序将忽略 SIGPIPE 信号，这意味着即使发生了向已关闭的管道或者 socket 
        //连接中写数据的情况，程序也不会因为收到 SIGPIPE 而终止。
        //这样可以让程序继续正常执行，而不受这种情况的影响。
        while (true)
        {
            std::string clientip;
            uint16_t clientport;
            int sockfd = listensock_.Accept(&clientip, &clientport);
            if (sockfd < 0)
                continue;
            lg(Info, "accept a new link, sockfd: %d, clientip: %s, clientport: %d", sockfd, clientip.c_str(), clientport);

            // 子进程提供服务
            if (fork() == 0)
            {
                listensock_.Close();
                std::string inbuffer_stream;
                // 数据计算
                while (true)
                {
                    //读到客户端发送的报文
                    char buffer[1280];
                    ssize_t n = read(sockfd, buffer, sizeof(buffer));
                    if (n > 0)
                    {   
                        //说明读取报文成功
                        buffer[n] = 0;
                        //每次都加上读取的数据是因为有可能我的一个完整报文分两次读取
                        //加上第二次的才能算上一个完整的报文
                        inbuffer_stream += buffer;

                        lg(Debug, "debug:\n%s", inbuffer_stream.c_str());

                        while (true)
                        {   
                            std::string info = callback_(inbuffer_stream);
                            //调用string Calculator(std::string &package)

                            if (info.empty())//没有读出说明数据处理失败
                                break;
                            lg(Debug, "debug, response:\n%s", info.c_str());
                            lg(Debug, "debug:\n%s", inbuffer_stream.c_str());
                            //write写入处理好后的计算过的数据（经过了序列化）
                            write(sockfd, info.c_str(), info.size());
                        }
                    }
                    else if (n == 0)
                        break;
                    else
                        break;
                }

                exit(0);
            }
            //父进程关闭多余的文件描述符
            close(sockfd);
        }
    }
    ~TcpServer()
    {
    }

private:
    uint16_t port_;
    Sock listensock_;
    func_t callback_;
};

5.Protocol（自定义协议）

#pragma once

#include <iostream>
#include <string>
#include <jsoncpp/json/json.h>
 

const std::string blank_space_sep = " ";
const std::string protocol_sep = "\n";


//编码：给序列化后的字符串加上字符长度与\n
std::string Encode(std::string &content)
{
    std::string package = std::to_string(content.size());
    package += protocol_sep;
    package += content;
    package += protocol_sep;
// "len"\n"x op y"\nXXXXXX
    return package;
}

 
// "protocolnumber"\n"len"\n"x op y"\nXXXXXX
//目的：截取字符串“x op y”放入content中，并把与此字符串
//相关的数据从总报文package中移除
bool Decode(std::string &package, std::string *content)
{
    
    std::size_t pos = package.find(protocol_sep);
    if(pos == std::string::npos) return false;

    //len_str:len的字符串形式
    std::string len_str = package.substr(0, pos);
    std::size_t len = std::stoi(len_str);
    // package = len_str + content_str + 2
    //
    std::size_t total_len = len_str.size() + len + 2;
    if(package.size() < total_len) return false;

    *content = package.substr(pos+1, len);
    // earse 移除报文 package.erase(0, total_len);
    package.erase(0, total_len);

    return true;
}


// json, protobuf
class Request
{
public:
    Request(int data1, int data2, char oper) : x(data1), y(data2), op(oper)
    {
    }
    Request()
    {}
public:
    bool Serialize(std::string *out)
    {
#ifdef MySelf
        // 构建报文的有效载荷
        // struct => string, "x op y"
        std::string s = std::to_string(x);
        s += blank_space_sep;
        s += op;
        s += blank_space_sep;
        s += std::to_string(y);
        *out = s;
        return true;
#else
        Json::Value root;
        root["x"] = x;
        root["y"] = y;
        root["op"] = op;
        // Json::FastWriter w;
        Json::StyledWriter w;
        *out = w.write(root);
        return true;
#endif
    }
    bool Deserialize(const std::string &in) 
    // 目的：从"x op y"中分离出x=?,y=?,op=?填入类的成员变量
    {
#ifdef MySelf
        std::size_t left = in.find(blank_space_sep);
        if (left == std::string::npos)
            return false;
        std::string part_x = in.substr(0, left);

        std::size_t right = in.rfind(blank_space_sep);
        if (right == std::string::npos)
            return false;
        std::string part_y = in.substr(right + 1);

        if (left + 2 != right)
            return false;
        op = in[left + 1];
        x = std::stoi(part_x);
        y = std::stoi(part_y);
        return true;
#else
        Json::Value root;
        Json::Reader r;
        r.parse(in, root);

        x = root["x"].asInt();
        y = root["y"].asInt();
        op = root["op"].asInt();
        return true;
#endif
    }
    void DebugPrint()
    {
        std::cout << "新请求构建完成:  " << x << op << y << "=?" << std::endl;
    }
public:
    // x op y
    int x;
    int y;
    char op; // + - * / %
};

class Response
{
public:
    Response(int res, int c) : result(res), code(c)
    {
    }

    Response()
    {}
public:
    bool Serialize(std::string *out)
    {
#ifdef MySelf
        // "result code"
        // 构建报文的有效载荷
        std::string s = std::to_string(result);
        s += blank_space_sep;
        s += std::to_string(code);
        *out = s;
        return true;
#else
        Json::Value root;
        root["result"] = result;
        root["code"] = code;
        // Json::FastWriter w;
        Json::StyledWriter w;
        *out = w.write(root);
        return true;
#endif
    }
    bool Deserialize(const std::string &in) // "result code"
    {
#ifdef MySelf
        std::size_t pos = in.find(blank_space_sep);
        if (pos == std::string::npos)
            return false;
        std::string part_left = in.substr(0, pos);
        std::string part_right = in.substr(pos+1);

        result = std::stoi(part_left);
        code = std::stoi(part_right);

        return true;
#else
        Json::Value root;
        Json::Reader r;
        r.parse(in, root);

        result = root["result"].asInt();
        code = root["code"].asInt();
        return true;
#endif

    }
    void DebugPrint()
    {
        std::cout << "结果响应完成, result: " << result << ", code: "<< code << std::endl;
    }
public:
    int result;
    int code; // 0，可信，否则!0具体是几，表明对应的错误原因
};

二、用户端

1.ClientCal

#include <iostream>
#include <string>
#include <ctime>
#include <cassert>
#include <unistd.h>
#include "Socket.hpp"
#include "Protocol.hpp"

static void Usage(const std::string &proc)
{
    std::cout << "\nUsage: " << proc << " serverip serverport\n"
              << std::endl;
}

// ./clientcal ip port
int main(int argc, char *argv[])
{
    if (argc != 3)
    {
        Usage(argv[0]);
        exit(0);
    }
    std::string serverip = argv[1];
    uint16_t serverport = std::stoi(argv[2]);

    Sock sockfd;
    sockfd.Socket();
    bool r = sockfd.Connect(serverip, serverport);
    if(!r) return 1;

    srand(time(nullptr) ^ getpid());
    int cnt = 1;
    const std::string opers = "+-*/%=-=&^";

    std::string inbuffer_stream;
    while(cnt <= 10)
    {
        std::cout << "===============第" << cnt << "次测试....., " << "===============" << std::endl;
        int x = rand() % 100 + 1;
        usleep(1234);
        int y = rand() % 100;
        usleep(4321);
        char oper = opers[rand()%opers.size()];
        Request req(x, y, oper);//构造需求
        req.DebugPrint();

        std::string package;
        req.Serialize(&package);

        package = Encode(package);

        //经过序列化传给服务器
        write(sockfd.Fd(), package.c_str(), package.size());
        

        char buffer[128];
        ssize_t n = read(sockfd.Fd(), buffer, sizeof(buffer)); // 我们也无法保证我们能读到一个完整的报文
        if(n > 0)
        {   
            //读取服务器处理后的报文
            buffer[n] = 0;
            inbuffer_stream += buffer; // "len"\n"result code"\n
            std::cout << inbuffer_stream << std::endl;
            std::string content;
            bool r = Decode(inbuffer_stream, &content);  
            // 目的：得到字符串"result code"
            assert(r);

            Response resp;
            。。反序列化
            r = resp.Deserialize(content);
            assert(r);

            resp.DebugPrint();
        }

        std::cout << "=================================================" << std::endl;
        sleep(1);

        cnt++;
    }


    sockfd.Close();
    return 0;
}

三、Log.hpp（日志）

详细可参考我之前写的博客【Linux】记录错误信息日志的实现

#pragma once

#include <iostream>
#include <time.h>
#include <stdarg.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>

using namespace std;

#define SIZE 1024

#define Info 0
#define Debug 1
#define Warning 2
#define Error 3 
#define Fatal 4

#define Screen 1
#define Onefile 2
#define ClassFile 3

#define LogFile "log.txt"

class Log{
public:
Log(){
    printMethod=Screen;
    path="./log/";
}

void Enable(int method){
    printMethod=method;
}

 string levelToString(int level)
    {
        switch (level)
        {
        case Info:
            return "Info";
        case Debug:
            return "Debug";
        case Warning:
            return "Warning";
        case Error:
            return "Error";
        case Fatal:
            return "Fatal";
        default:
            return "None";
        }
    }

void printLog(int level,const string&logtxt){
    switch(printMethod){
        case Screen:
            cout<<logtxt<<endl;
            break;
        case Onefile:
            printOneFile(LogFile,logtxt);
            break;
        case ClassFile:
            printClassFile(level,logtxt);
            break;
        default:
            break;
    }
}

void printOneFile(const string&logname,const string&logtxt){
    string _logname=path+logname;
    int fd=open(_logname.c_str(),O_WRONLY|O_CREAT|O_APPEND,0666);
    if(fd<0){
        return ;
    }
    write(fd,logtxt.c_str(),logtxt.size());
    close(fd);
}

void printClassFile(int level,const string&logtxt){
    string filename=LogFile;
    filename+=".";
    filename+=levelToString(level);
    printOneFile(filename,logtxt);
}

~Log(){

}

 void operator()(int level, const char *format, ...)
    {
        time_t t = time(nullptr);
        struct tm *ctime = localtime(&t);
        char leftbuffer[SIZE];
        snprintf(leftbuffer, sizeof(leftbuffer), "[%s][%d-%d-%d %d:%d:%d]", levelToString(level).c_str(),
                 ctime->tm_year + 1900, ctime->tm_mon + 1, ctime->tm_mday,
                 ctime->tm_hour, ctime->tm_min, ctime->tm_sec);

        va_list s;
        va_start(s, format);
        char rightbuffer[SIZE];
        vsnprintf(rightbuffer, sizeof(rightbuffer), format, s);
        va_end(s);

        // 格式：默认部分+自定义部分
        char logtxt[SIZE * 2];
        snprintf(logtxt, sizeof(logtxt), "%s %s", leftbuffer, rightbuffer);

        // printf("%s", logtxt); // 暂时打印
        printLog(level, logtxt);
    }

private:
    int printMethod;
    string path;
};

Log lg;

四、makefile

.PHONY:all
all:servercal clientcal

Flag=#-DMySelf=1
Lib=-ljsoncpp

servercal:ServerCal.cc
	g++ -o $@ $^ -std=c++11 $(Lib) $(Flag)
clientcal:ClientCal.cc
	g++ -o $@ $^ -std=c++11 $(Lib) $(Flag)


.PHONY:clean
clean:
	rm -f clientcal servercal