思维导图

练习题

1> UDP传输实现聊天室

服务器端

#include <myhead.h>
#define SER_IP "192.168.125.151"
#define SER_PORT 9999
typedef struct Msg
{
    char user[32];   //用户名
    int type;        //执行操作1.登录、2.发消息、0.退出
    char text[1024]; //消息内容
} msg_t;
typedef struct List
{
    struct sockaddr_in cin; //客户端的网络信息结构体
    struct List *next;      //链表指针，指向下一个
} * list;

struct sockaddr_in cin;
//创建头节点
list list_create()
{
    list p = (list)malloc(sizeof(struct List));
    if (p == NULL)
    {
        perror("create list error");
    }
    p->next = NULL;
    p = NULL;
}
//线程函数事件 向所有客户端发送消息
void *task(void *arg)
{
    int *sockfd = (int *)arg;
    msg_t msg;
    strcpy(msg.user, "*system*");
    while (1)
    {
        scanf("%s", msg.text);
        getchar();
        if (strncmp(msg.text, "quit", 4) == 0)
        {
            exit(0);
        }
        sendto(*sockfd, msg.text, sizeof(msg), 0, (struct sockaddr *)&cin, sizeof(cin));
    }
}
//登录事件处理
void login(int sockfd, msg_t msg, list p, struct sockaddr_in cin)
{
    //新客户端插入链表
    list new = NULL;
    new = (list)malloc(sizeof(struct List));
    sprintf(msg.text, "login");
    while (p->next != NULL)
    {
        //发送给的其他客户端登录消息
        p = p->next;
        sendto(sockfd, &msg, sizeof(msg), 0, (struct sockaddr *)&(p->cin), sizeof(p->cin));
        printf("[%s:%d]:%s login\n", inet_ntoa(cin.sin_addr), ntohs(cin.sin_port), msg.user);
    }
    //新节点的数据域填充新客户端地址结构体，尾插
    new->cin = cin;
    p->next = new;
    new->next = NULL;
}
//接收客户端消息事件处理
void chatmsg(int sockfd, msg_t msg, list p, struct sockaddr_in cin)
{
    //将客户端发来的消息发送给其他客户端
    while (p->next != NULL)
    {
        p = p->next;
        sendto(sockfd, &msg, sizeof(msg), 0, (struct sockaddr *)&(p->cin), sizeof(p->cin));
    }
}
//客户端退出消息事件处理
void quit(int sockfd, msg_t msg, list p, struct sockaddr_in cin)
{
    list del = NULL;
    sprintf(msg.text, "%s out", msg.user);
    while (p->next != NULL)
    {
        //遍历链表找到要退出的客户端地址结构体的前一个
        if (memcmp(&(p->next->cin), &cin, sizeof(cin)) == 0)
        {
            del = p->next;
            p->next = del->next;
            free(del);
            del = NULL;
        }
        else
        {
            p = p->next;
            sendto(sockfd, &msg, sizeof(msg), 0, (struct sockaddr *)&(p->cin), sizeof(p->cin));
        }
    }
}
int main(int argc, char const *argv[])
{
    msg_t msg;
    //创建套接字
    int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
    if (sockfd == -1)
    {
        perror("socket error");
        return -1;
    }
    struct sockaddr_in sin;
    //填充服务器地址结构体
    sin.sin_family = AF_INET;
    sin.sin_port = htons(SER_PORT);
    sin.sin_addr.s_addr = inet_addr(SER_IP);
    //绑定服务器
    if (bind(sockfd, (struct sockaddr *)&sin, sizeof(sin)) == -1)
    {
        perror("bind error");
        return -1;
    }
    //创建客户端地址结构体
    struct sockaddr_in cin;
    //获取客户端地址结构体大小
    socklen_t socklen = sizeof(cin);
    //创建链表节点
    list p = list_create();
    //创建线程
    pthread_t tid;
    if (pthread_create(&tid, NULL, task, &sockfd) == -1)
    {
        printf("pthread_create error\n");
        return -1;
    }
    //分离线程
    pthread_detach(tid);
    //接收客户端消息
    while (1)
    {

        //接收客户端发来的消息，返回消息字符个数
        int res = recvfrom(sockfd, &msg, sizeof(msg), 0, (struct sockaddr *)&cin, &socklen);
        if (res < 0)
        {
            perror("recvfrom error");
            return -1;
        }
        //判断三种客户端状态 1登录 2消息 0退出
        if (msg.type == 1)
        {
            login(sockfd, msg, p, cin);
        }
        else if (msg.type == 2)
        {
            chatmsg(sockfd, msg, p, cin);
        }
        else if (msg.type == 0)
        {
            printf("[%s:%d] %s out\n", inet_ntoa(cin.sin_addr), ntohs(cin.sin_port), msg.user);
            quit(sockfd, msg, p, cin);
        }
    }
    //关闭套接字
    close(sockfd);
    return 0;
}

客户端

#include <myhead.h>
#define SER_IP "192.168.125.151"
#define SER_PORT 9999
typedef struct Msg
{
    char user[32];   //用户名
    int type;        //执行操作1.登录、2.发消息、0.退出
    char text[1024]; //消息内容
} msg_t;
int main(int argc, char const *argv[])
{
    int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
    if (sockfd == -1)
    {
        perror("sock error");
        return -1;
    }
    msg_t msg;
    struct sockaddr_in cin;
    cin.sin_family = AF_INET;
    cin.sin_addr.s_addr = inet_addr(SER_IP);
    cin.sin_port = htons(SER_PORT);
    socklen_t socklen = sizeof(cin);
    char buf[128] = "";

    msg.type = 1;
    printf("please imput your name:");
    scanf("%s", msg.user);
    getchar();

    sendto(sockfd, &msg, sizeof(msg), 0, (struct sockaddr *)&cin, socklen);

    pid_t pid = fork();
    if (pid < 0)
    {
        perror("fork error");
        return -1;
    }
    else if (pid == 0) //子进程循环发送消息
    {
        while (1)
        {
            printf("---------------------\n");
            scanf("%s", msg.text);
            getchar();
            if (strncmp(msg.text, "quit", 4) == 0)
            {
                msg.type = 0;
                sendto(sockfd, &msg, sizeof(msg), 0, (struct sockaddr *)&cin, socklen);
                kill(pid, SIGINT);
                exit(0);
                wait(NULL);
            }
            else
            {
                msg.type = 2;
            }
            sendto(sockfd, &msg, sizeof(msg), 0, (struct sockaddr *)&cin, socklen);
        }
    }
    else //父进程循环接受消息
    {
        int res;
        while (1)
        {
            res = recv(sockfd, &msg, sizeof(msg), 0);
            if (res == -1)
            {
                perror("recv error");
                return -1;
            }
            printf("[%s]:%s\n", msg.user, msg.text);
        }
        wait(NULL);
    }
    close(sockfd);
    return 0;
}