网络编程练习：UDP聊天室

 【1】服务器代码

#include <stdio.h>
#include <sys/types.h> /* See NOTES */
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>
#include <stdlib.h>
#include <stdarg.h>
#include "head.h"

// 服务器-------------------------------------------------------------------------》短信的接收方

/*创建一个空的单向链表*/
Node_p Create();

/*登录，聊天，退出*/
void login(int fd_s, Msg msg, Node_p p, struct sockaddr_in caddr);
void chat(int fd_s, Msg msg, Node_p p, struct sockaddr_in caddr);
void quit(int fd_s, Msg msg, Node_p p, struct sockaddr_in caddr);

int main(int argc, char const *argv[])
{
    int fd_s;
    // 1.创建数据报套接字（socket）------------------》有手机
    fd_s = socket(AF_INET, SOCK_DGRAM, 0);
    if (fd_s < 0)
    {
        perror("soc err\n");
        return -1;
    }
    // printf("%d\n", fd_s);
    // 2.指定网络信息--------------------------------------》有号码
    struct sockaddr_in saddr, caddr;
    saddr.sin_family = AF_INET;
    saddr.sin_port = htons(atoi(argv[1]));
    saddr.sin_addr.s_addr = INADDR_ANY;
    int len = sizeof(caddr);

    // 3.绑定套接字（bind）------------------------------》绑定手机
    if (bind(fd_s, (struct sockaddr *)&saddr, sizeof(saddr)) < 0)
    {
        perror("bind err\n");
        return -1;
    }
    // printf("bind ok\n");

    printf("欢迎使用欢欢聊天室\n");

    Msg msg;
    Node_p p = Create(); // 创建空链表

    pid_t pid;
    pid = fork(); // 创建新进程
    if (pid < 0)
    {
        perror("fork err\n");
        return -1;
    }
    else if (pid == 0)
    {
        fgets(msg.text, sizeof(msg.text), stdin);
        if (msg.text[strlen(msg.text) - 1] == '\n')
            msg.text[strlen(msg.text) - 1] = '\0';
        msg.type = 'C';
        strcpy(msg.name, "server");

        sendto(fd_s, &msg, sizeof(msg), 0, (struct sockaddr *)&saddr, len);
    }
    else
    {
        // 4.接收、发送消息（recvfrom sendto）-------》收短信
        while (1)
        {
            int ret;
            ret = recvfrom(fd_s, &msg, sizeof(msg), 0, (struct sockaddr *)&caddr, &len);
            if (ret < 0)
            {
                perror("recv err\n");
                return -1;
            }
            // printf("addr: %s  port: %d\n", inet_ntoa(saddr.sin_addr), ntohs(saddr.sin_port));
            if (msg.type == 'L')
            {
                // printf("addr: %s  port: %d\n", inet_ntoa(saddr.sin_addr), ntohs(saddr.sin_port));
                printf("<%s> 已登录\n", msg.name);
                sprintf(msg.text, "<%s> 已登录", msg.name);
                login(fd_s, msg, p, caddr);
            }
            else if (msg.type == 'C')
            {

                printf("[%s]: %s\n", msg.name, msg.text);
                chat(fd_s, msg, p, caddr);
            }
            else if (msg.type == 'Q')
            {
                sprintf(msg.text, "<%s> 已下线", msg.name);
                printf("<%s> 已下线\n", msg.name);
                quit(fd_s, msg, p, caddr);
            }
        }
    }
    // 5.关闭套接字（close）----------------------------》接收完毕
    close(fd_s);
    return 0;
}

/*创空表*/
Node_p Create()
{
    Node_p p = (Node_p)malloc(sizeof(Node_t)); // 开辟一个节点大小的堆区空间
    if (NULL == p)                             // 开辟失败
    {
        printf("malloc lost");
        return NULL;
    }
    p->next = NULL; // 初始化头节点指针域
    return p;       // 开辟成功,返回
}

/*登录*/
void login(int fd_s, Msg msg, Node_p p, struct sockaddr_in caddr)
{
    while (p->next != NULL)
    {
        p = p->next;
        sendto(fd_s, &msg, sizeof(msg), 0, (struct sockaddr *)&(p->addr), sizeof(p->addr));
    }

    /*创建新的节点*/
    Node_p p_new = (Node_p)malloc(sizeof(Node_t));
    if (p_new == NULL)
    {
        perror("malloc err\n");
        return;
    }

    /*初始化节点*/
    p_new->addr = caddr;
    p_new->next = NULL;

    /*将新节点连接到链表中*/
    p->next = p_new;
    // p = p_new;
    return;
}

/*聊天*/
void chat(int fd_s, Msg msg, Node_p p, struct sockaddr_in caddr)
{
    while (p->next != NULL)
    {
        p = p->next;
        if ((memcmp(&(p->addr), &caddr, sizeof(caddr))) == 0)
        {
            continue;
        }
        sendto(fd_s, &msg, sizeof(msg), 0, (struct sockaddr *)&(p->addr), sizeof(p->addr));
    }
}

/*退出*/
void quit(int fd_s, Msg msg, Node_p p, struct sockaddr_in caddr)
{
    while (p->next != NULL)
    {
        if ((memcmp(&(p->next->addr), &caddr, sizeof(caddr))) == 0)
        {
            Node_p p_del = NULL;
            p_del = p->next;
            p->next = p_del->next;
            free(p_del);
            p_del = NULL;
            continue;
        }
        else
        {
            p = p->next;
            sendto(fd_s, &msg, sizeof(msg), 0, (struct sockaddr *)&(p->addr), sizeof(p->addr));
        }
    }
    return;
}

【2】客户端代码 

#include <stdio.h>
#include <sys/types.h> /* See NOTES */
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>
#include <stdlib.h>
#include "head.h"
#include <pthread.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/wait.h>

// 客户端---------------------------------------------------------------------------》短信的发送方

struct sockaddr_in saddr;
int len = sizeof(saddr);

int main(int argc, char const *argv[])
{
    // 1.创建数据报套接字（socket）------------------》有手机
    int fd_c;
    fd_c = socket(AF_INET, SOCK_DGRAM, 0);
    if (fd_c < 0)
    {
        perror("soc err\n");
        return -1;
    }
    // printf("%d\n", fd_c);
    // 2.指定网络信息--------------------------------------》有对方号码
    saddr.sin_family = AF_INET;
    saddr.sin_port = htons(atoi(argv[1]));
    saddr.sin_addr.s_addr = inet_addr("192.168.31.187");

    Msg msg;
    msg.type = 'L';
    printf("欢迎使用欢欢聊天室\n");
    printf("请输入用户名：");
    fgets(msg.name, N, stdin);
    if (msg.name[strlen(msg.name) - 1] == '\n')
        msg.name[strlen(msg.name) - 1] = '\0';

    sendto(fd_c, &msg, sizeof(msg), 0, (struct sockaddr *)&saddr, sizeof(saddr));

    pid_t pid = fork();
    if (pid < 0)
    {
        perror("fork err");
        exit(-1);
    }
    else if (pid == 0)
    {
        while (1)
        {
            if (recvfrom(fd_c, &msg, sizeof(msg), 0, NULL, NULL) < 0)
            {
                perror("recvfrom err");
                return -1;
            }
            if (msg.type == 'L')
                printf("%s\n", msg.text);
            else if (msg.type == 'C')
                printf("[%s]:%s\n", msg.name, msg.text);
            else if (msg.type == 'Q')
                printf("%s\n", msg.text);
        }
    }
    else
    {
        while (1)
        {
            fgets(msg.text, sizeof(msg.text), stdin);
            if (msg.text[strlen(msg.text) - 1] == '\n')
                msg.text[strlen(msg.text) - 1] = '\0';
            if (strcmp(msg.text, "quit") == 0)
            {
                msg.type = 'Q';
                sendto(fd_c, &msg, sizeof(msg), 0, (struct sockaddr *)&saddr, len);
                kill(pid, SIGKILL);
                wait(NULL);
                exit(-1);
            }
            else
            { 
                msg.type = 'C';
            }
            // 发送消息
            sendto(fd_c, &msg, sizeof(msg), 0, (struct sockaddr *)&saddr, len);
        }
    }
    close(fd_c);

    return 0;
}

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