C語言socket編程

 

建議先去看一下思路

真的寫的很不錯呦~

思路參考博客：http://www.javashuo.com/article/p-xiygeust-bz.html

 

linux c語言socket編程代碼（單一服務端與客戶端） 【此代碼有bug，但很方便理解，用於理解使用】： 

代碼參考博客：https://www.cnblogs.com/xudong-bupt/p/3483059.html

服務端代碼：

#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/shm.h>

#define MYPORT  8887
#define QUEUE   20
#define BUFFER_SIZE 1024

int main() {
    // 實例化socket對象， 定義sockfd
    /* AF_INET 默認爲IPv4
     * SOCK_STREAM 流式socket， for TCP
     * 0 協議， 默認選擇合適的協議
     * */
    int server_sockfd = socket(AF_INET, SOCK_STREAM, 0);

    ///定義sockaddr_in
    struct sockaddr_in server_sockaddr;
    server_sockaddr.sin_family = AF_INET;
    server_sockaddr.sin_port = htons(MYPORT);
    server_sockaddr.sin_addr.s_addr = htonl(INADDR_ANY);

    // 將套接字綁定到地址
    // bind，成功返回0，出錯返回-1
    if (bind(server_sockfd, (struct sockaddr *) &server_sockaddr, sizeof(server_sockaddr)) == -1) {
        perror("bind");
        exit(1);
    }

    // 監聽
    // listen，成功返回0，出錯返回-1
    if (listen(server_sockfd, QUEUE) == -1) {
        perror("listen");
        exit(1);
    }

    // 客戶端套接字
    char buffer[BUFFER_SIZE];
    struct sockaddr_in client_addr;
    socklen_t length = sizeof(client_addr);

    // 進入阻塞狀態，等待客戶鏈接
    // 成功返回非負描述字，出錯返回-1
    int conn = accept(server_sockfd, (struct sockaddr *) &client_addr, &length);
    if (conn < 0) {
        perror("connect");
        exit(1);
    }
    // 循環
    while (1) {
        memset(buffer, 0, sizeof(buffer));
        // 接受消息
        int len = recv(conn, buffer, sizeof(buffer), 0);
        printf("len: %d\n", len); 
        //這裏是一直循環的，若是客戶端說一句話，而後結束之後，這裏一直循環，須要注意
        
        if (strcmp(buffer, "exit\n") == 0)
            break;
        fputs(buffer, stdout);
        // 發送消息
        send(conn, "hehe", 5, 0);
    }
    close(conn);
    close(server_sockfd);
    return 0;
}

 

客戶端代碼：

#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/shm.h>

#define MYPORT  8887
#define BUFFER_SIZE 1024

int main()
{
    ///定義sockfd
    int sock_cli = socket(AF_INET,SOCK_STREAM, 0);

    ///定義sockaddr_in
    struct sockaddr_in servaddr;
    memset(&servaddr, 0, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(MYPORT);  ///服務器端口
    servaddr.sin_addr.s_addr = inet_addr("127.0.0.1");  ///服務器ip

    ///鏈接服務器，成功返回0，錯誤返回-1
    if (connect(sock_cli, (struct sockaddr *)&servaddr, sizeof(servaddr)) < 0)
    {
        perror("connect");
        exit(1);
    }

    char sendbuf[BUFFER_SIZE];
    char recvbuf[BUFFER_SIZE];
    while (fgets(sendbuf, sizeof(sendbuf), stdin) != NULL)
    {
        send(sock_cli, sendbuf, strlen(sendbuf),0); ///發送
        if(strcmp(sendbuf,"exit\n")==0)
            break;
        recv(sock_cli, recvbuf, sizeof(recvbuf),0); ///接收
        fputs(recvbuf, stdout);

        memset(sendbuf, 0, sizeof(sendbuf));
        memset(recvbuf, 0, sizeof(recvbuf));
    }

    close(sock_cli);
    return 0;
}

 

採用C/S架構，Tcp、Ip協議，服務器端使用共享內存的方式，不一樣客戶端鏈接服務端，實現網絡聊天室的功能（多用戶）

服務端：

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h> //數據類型定義
#include <sys/stat.h> //文件屬性
#include <netinet/in.h> //定義數據結構sockaddr_in
#include <sys/socket.h> //提供socket函數和數據結構
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <sys/ipc.h>
#include <errno.h>
#include <sys/shm.h> //共享內存
#include <time.h>
#include<sys/time.h>
#include <arpa/inet.h>

#define PERM S_IRUSR | S_IWUSR //用戶讀寫
#define MYPORT  8080 //通訊端口
#define BACKLOG 10 //定義服務器段能夠鏈接的最大客戶數
#define MYHOST  "192.168.2.137"
#define WELCOME "|---------------Welcome to the chat room!----------------|"//當客戶端鏈接服務端時，向客戶端發送此字符串

//將int類型轉換成char*類型
void itoa(int i, char *string) {
    int mask = 1;
    while (i / mask >= 10)
        mask *= 10;
    while (mask > 0) {
        *string++ = i / mask + '0';
        i %= mask;
        mask /= 10;
    }
    *string = '\0';
}

//獲得當前系統的時間
void get_cur_time(char *time_str) {
    struct timeval now;
    gettimeofday(&now, NULL);
    strcpy(time_str, ctime(&now.tv_sec));
}

//建立共享存儲區
int shm_create() {
    int shmid;
    //shmid = shmget(IPC_PRIVATE, 1024, PERM);
    if ((shmid = shmget(IPC_PRIVATE, 1024, PERM)) == -1) {
        fprintf(stderr, "Create Share Memory Error:%s\n\a", strerror(errno));
        exit(1);
    }
    return shmid;
}

//端口綁定函數。建立套接字，並綁定到指定端口
int bindPort(unsigned short int port) {
    int sockfd;
    struct sockaddr_in my_addr;
    sockfd = socket(AF_INET, SOCK_STREAM, 0); //建立基於流套接字
    //bzero(&(my_addr.sin_zero),0);
    bzero(&my_addr, sizeof(my_addr));
    my_addr.sin_family = AF_INET; //IPV4協議族
    my_addr.sin_port = htons(port); //轉換端口爲網絡字節序
    my_addr.sin_addr.s_addr = inet_addr(MYHOST);

    if (bind(sockfd, (struct sockaddr *) &my_addr, sizeof(struct sockaddr)) == -1) {
        perror("fail to bind");
        exit(1);
    }

    printf("bind success!\n");
    return sockfd;
}

int main(int argc, char *argv[]) {
    int sockfd, clientfd; //監聽套接字、客戶套接字
    int sin_size, recvbytes;

    pid_t pid, ppid; //定義父子進程標記
    char *buf, *read_addr, *write_addr, *temp, *time_str; //須要用到的緩衝區
    struct sockaddr_in their_addr; //定義地址結構
    int shmid;

    shmid = shm_create(); //建立共享存儲區

    temp = (char *) malloc(255);
    time_str = (char *) malloc(50);
    sockfd = bindPort(MYPORT); //綁定端口

    get_cur_time(time_str);
    printf("Time is : %s\n", time_str);

    if (listen(sockfd, BACKLOG) == -1) {
        //在指定端口上監聽
        perror("fail to listen");
        exit(1);
    }

    printf("listen....\n");
    while (1) {
        /*
        if (listen(sockfd, BACKLOG) == -1)
        {
            perror("fail to listen");
            exit(1);
        }
        */
        //接受一個客戶端的鏈接請求
        if ((clientfd = accept(sockfd, (struct sockaddr *) &their_addr, &sin_size)) == -1) {
            perror("fail to accept");
            exit(1);
        }

        //獲得客戶端的IP地址輸出
        char address[20];
        inet_ntop(AF_INET, &their_addr.sin_addr, address, sizeof(address));

        printf("accept from %s\n", address);
        send(clientfd, WELCOME, strlen(WELCOME), 0); //發送問候信息
        buf = (char *) malloc(255);

        ppid = fork(); //建立子進程
        if (ppid == 0) //子進程
        {
            pid = fork(); //子進程建立子進程
            while (1) {
                if (pid > 0) {
                    //buf = (char *)malloc(255);
                    //父進程用於接收信息
                    memset(buf, 0, 255);
                    printf("OK\n");
                    if ((recvbytes = recv(clientfd, buf, 255, 0)) <= 0) {
                        perror("fail to recv");
                        close(clientfd);
                        raise(SIGKILL);
                        exit(1);
                    }
                    write_addr = shmat(shmid, 0, 0); //shmat將shmid所表明的全局的共享存儲區關聯到本進程的進程空間
                    memset(write_addr, '\0', 1024);

                    //把接收到的消息存入共享存儲區中
                    strncpy(write_addr, buf, 1024);

                    //把接收到的消息鏈接此刻的時間字符串輸出到標準輸出
                    get_cur_time(time_str);
                    strcat(buf, time_str);
                    printf(" %s\n", buf);
                } else if (pid == 0) {
                    //子進程用於發送消息
                    sleep(1); //子進程先等待父進程把接收到的信息存入共享存儲區
                    read_addr = shmat(shmid, 0, 0); //讀取共享存儲區的內容

                    //temp存儲上次讀取過的內容,每次先判斷是否已經讀取過該消息
                    if (strcmp(temp, read_addr) != 0) {
                        strcpy(temp, read_addr); //更新temp，表示已經讀取過該消息

                        get_cur_time(time_str);
                        strcat(read_addr, time_str);
                        if (send(clientfd, read_addr, strlen(read_addr), 0) == -1) {
                            perror("fail to send");
                            exit(1);
                        }
                        memset(read_addr, '\0', 1024);
                        strcpy(read_addr, temp);
                    }
                } else
                    perror("fai to fork");
            }
        }
    }
    printf("------------------------------------\n");
    free(buf);
    close(sockfd);
    close(clientfd);
    return 0;
}

View Code

 

客戶端2、客戶端三...

#include <stdio.h>
#include <netinet/in.h> //定義數據結構sockaddr_in
#include <sys/socket.h> //定義socket函數以及數據結構
#include <sys/types.h>
#include <string.h>
#include <stdlib.h>
#include <netdb.h>
#include <unistd.h>
#include <signal.h>
#include <time.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#define MYPORT  8080
#define MYHOST  "192.168.2.137"



int main(int argc, char *argv[])
{
    struct sockaddr_in clientaddr; //定義地址結構
    pid_t pid;
    int clientfd, sendbytes, recvbytes;
    struct hostent *host; //主機信息數據結構
    char *buf, *buf_read;
//    if (argc < 4)
//    {
//        printf("wrong usage");
//        printf("%s host port name\n", argv[0]);
//        exit(1);
//    }
//    host = gethostbyname(argv[1]);
    if ((clientfd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
    {
        perror("fail to create socket");
        exit(1);
    }
    bzero(&clientaddr, sizeof(clientaddr));
    clientaddr.sin_family = AF_INET;
    clientaddr.sin_port = htons(MYPORT);
    clientaddr.sin_addr.s_addr = inet_addr(MYHOST);
    //客戶端鏈接服務端
    if (connect(clientfd, (struct sockaddr *)&clientaddr, sizeof(struct sockaddr)) == -1)
    {
        perror("fail to connect");
        exit(1);
    }
    buf = (char *)malloc(120);
    memset(buf, 0, 120);
    buf_read = (char *)malloc(100);

    if (recv(clientfd, buf, 100, 0) == -1)
    {
        perror("fail to recv");
        exit(1);
    }
    printf("\n%s\n", buf);
    pid = fork();
    while (1)
    {
        if (pid > 0)
        {
            //父進程發送消息
            strcpy(buf, "afsasdf");
            strcat(buf, ":");
            memset(buf_read, 0, 100);
            fgets(buf_read, 100, stdin);
            strncat(buf, buf_read, strlen(buf_read) - 1);
            if ((sendbytes = send(clientfd, buf, strlen(buf), 0)) == -1)
            {
                perror("fail to send");
                exit(1);
            }
        }
        else if (pid == 0)
        {
            //子進程接受消息
            memset(buf, 0, 100);
            if (recv(clientfd, buf, 100, 0) <= 0)
            {
                perror("fail to recv");
                close(clientfd);
                raise(SIGSTOP);
                exit(1);
            }
            printf("%s\n", buf);
        }
        else
            perror("fork error");
    }
    close(clientfd);
    return 0;
}

View Code