Linux下socket雙向通信

linux下的socket與windows下的類似，就是少一個初始化的過程。

服務端                         客戶端

1 創建socket            1 創建socket

2 綁定                        2 連接

3 監聽

4 接受

發送與接受消息，客戶端與服務端都是用的recv與send，在使用完成後記得close，以釋放端口資源。

下面是服務端

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <iostream>
using namespace std;
#include <pthread.h>

void* receiveMsg(void *sock)
{
    char buffer[4096];
    int* socket = (int*)sock;
    while (1) {
        memset(buffer,0,sizeof(buffer));
        ssize_t byteCount = recv(*socket, buffer, 4096, 0);
    if(byteCount <= 0)
        {
            continue;
        }
        cout << "recv:" <<buffer << endl;
    }
}

void* sendMsg(void* sock)
{
    while (1) {
        usleep(500);
        char buffer[4096];
        memset(buffer, 0, sizeof(buffer));
        cin >> buffer;
        if(strlen(buffer) < 0)
        {
            continue;
        }
        ssize_t byteCount = send(*(int*)sock, buffer, 4096, 0);
        if(byteCount < 0)
        {
            cout << "send failed" << endl;
        }
    }
}

int main()
{
    pthread_t sendPthread;
    pthread_t recvPthread;

    in_port_t servPort = 7777;
    int servSock;
    if ((servSock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0)//創建socket
    {
        cout << "socket error" << endl;
    }

    struct sockaddr_in servAddr;
    memset(&servAddr, '\0', sizeof(struct sockaddr_in));
    servAddr.sin_family = AF_INET;
    servAddr.sin_addr.s_addr = htonl(INADDR_ANY);//讓系統自動填充地址，不用自己去查明本機的地址是多少
    servAddr.sin_port = htons(servPort);

    if(bind(servSock, (struct sockaddr*)&servAddr, sizeof(servAddr)) < 0) //把套接字綁定到指定的地址與端口
    {
        cout << "bind error" << endl;
    }

    if(listen(servSock, 5)< 0)//開始監聽，等待客戶端的連接，listen調用之前，客戶端無法連接到服務端，第二個參數爲最大連接數
    {
        cout << "listen filed" << endl;
    }

    struct sockaddr_in clntAddr;
    socklen_t clntAddrLen = sizeof(clntAddr);
    int clntSock = accept(servSock, (struct sockaddr*)&clntAddr, &clntAddrLen);

    if (clntSock < 0)
    {
        cout << "accept error" << endl;
    }

    char clntName[1024];
    if (inet_ntop(AF_INET, &clntAddr.sin_addr.s_addr, clntName, sizeof(clntName)) != NULL) {
        cout << "Handling client: " << clntName << " port: " << ntohs(clntAddr.sin_port) << endl;;
    } else {
        cout << "client address get failed " << endl;
    }

    pthread_create(&sendPthread, NULL, sendMsg, &clntSock);
    pthread_create(&recvPthread, NULL, receiveMsg, &clntSock);
    pthread_join(sendPthread, 0);
    pthread_join(recvPthread, 0);
}

下面是客戶端

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <iostream>
using namespace std;

void* sendMsg(void * socket)
{
    int sock = *((int*)socket);
    while (1) {
        char msg[4096];
        memset(msg, 0, sizeof(msg));
        cin >> msg;
        size_t outputlength = strlen(msg);
        if (0 == outputlength)
        {
            continue;
        }

        ssize_t bytecount = send(sock, msg, outputlength, 0);//發送消息
        if (bytecount < 0) {
            cout << "send failed" << endl;
        }
    }
}

void* recvMsg(void * socket)
{
    int sock = *((int*)socket);
    while (1) {
        char msg[4096];
        memset(msg, 0, sizeof(msg));

        ssize_t bytecount = recv(sock, msg, sizeof(msg), 0); //接收消息
        if (bytecount <= 0) {
            continue;
        } else {
            cout << "recv:" << msg << endl;
        }

    }
}

int main()
{
    pthread_t recv;
    pthread_t send;
    char ipaddr[14] = "127.0.0.1";
    int port = 7777;
    int sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);//AF_INET指明使用ipv4，sock_stream指定使用流套接字，ipproto_tcp指定使用tcp協議

    if (sock < 0) {
        cout << "socket() failed" << endl;
    }

    struct sockaddr_in servAddr;//結構體用於存放地址
    memset(&servAddr, '\0', sizeof(struct sockaddr_in));
    servAddr.sin_family = AF_INET;

    int rtn = inet_pton(AF_INET, ipaddr, &servAddr.sin_addr.s_addr);//轉換ip地址格式，從本機字節序轉換成爲網絡字節序
    if (rtn == 0) {
        cout << "address wrong ,inet_pton() failed" << endl;
    } else if (rtn < 0) {
        cout << "inet_pton() failed" << endl;
    }

    servAddr.sin_port = htons(port);

    if(connect(sock, (struct sockaddr*)&servAddr, sizeof(servAddr)) < 0)//連接到服務器
    {
        cout << "connect failed" << endl;
    }

    pthread_create(&recv, NULL, recvMsg, &sock);
    pthread_create(&send, NULL, sendMsg, &sock);
    pthread_join(recv, 0);
    pthread_join(recv, 0);

    close(sock);
}

注意：網絡接收到的數據可能是不安全的，在使用printf等函數時要注意安全。