2014-04-03 Linux网络编程 - 基于UDP的多人群聊

/* server.c */
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <stdlib.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/socket.h>
struct LinkNode            //链表，储存连接服务器的所有客户端地址信息
{
    struct sockaddr_in client_addr ;
    struct LinkNode * next ;
}LinkNode;
typedef struct LinkNode* LinkList;
void init_list(LinkList * L)        //初始化链表
{
    (*L)=(LinkList)malloc(sizeof(LinkNode));
    memset(&((*L)->client_addr), 0, sizeof(struct sockaddr_in)) ;
    (*L)->next = NULL;
}
void add_client(LinkList L, struct sockaddr_in new_client_addr)    //添加新地址
{
    LinkList p = L ;
    LinkList tail ;
    tail = (LinkList)malloc(sizeof(LinkNode)) ;
    memset(tail, 0, sizeof(LinkNode)) ;
    while(p->next != NULL)
    {
        p = p->next ;
    }
    tail->client_addr = new_client_addr ;    //可以结构体直接赋值
    //tail->client_addr.sin_family = new_client_addr.sin_family ;
    //tail->client_addr.sin_port =new_client_addr.sin_port ;
    //tail->client_addr.sin_addr.s_addr = new_client_addr.sin_addr.s_addr ;
    p->next = tail ;
    tail->next = NULL ;
}
void del_client(LinkList L, struct sockaddr_in offline_client)    //删除下线客户端地址
{
    LinkList del, p = L ;
    while(p->next != NULL)
    {
        if(offline_client.sin_addr.s_addr == p->next->client_addr.sin_addr.s_addr && offline_client.sin_port == p->next->client_addr.sin_port)
            break ;
        p = p->next ;
    }
    del = p->next ;
    p->next = del->next ;
    //free(del) ;
}
int main(int argc, char * argv[])  // ---> ./exe [port]
{
    int server_fd, iret ;
    char recv_buf[128], send_buf[128], message[128];
    struct sockaddr_in server_addr, cli_addr ;
    LinkList L, p;
    init_list(&L) ;
    //socket
    server_fd = socket(AF_INET, SOCK_DGRAM, 0) ;
    if(server_fd == -1)
    {
        perror("socket");
        exit(-1) ;
    }
    //bind
    memset(&server_addr, 0, sizeof(server_addr)) ;
    server_addr.sin_family = AF_INET ;
    server_addr.sin_port = htons(atoi(argv[1])) ;
    server_addr.sin_addr.s_addr = INADDR_ANY ;
    iret = bind(server_fd, (const struct sockaddr *)&server_addr, sizeof(server_addr)) ;
    if(iret == -1)
    {
        perror("bind") ;
        exit(-1) ;
    }
    while(1)
    {
        //recvfrom
        memset(&cli_addr, 0, sizeof(cli_addr)) ;
        memset(recv_buf, 0, 128) ;
        int len = sizeof(cli_addr) ;
        recvfrom(server_fd, recv_buf, 128, 0, (struct sockaddr*)&cli_addr, &len) ;
        //add_client
        if(strcmp(recv_buf, "online\n") == 0)    //有客户端上线时新增地址到链表
        {
            add_client(L, cli_addr) ;
            printf("online!!!\n") ;
        }
        //del_client
        else if(strcmp(recv_buf, "offline\n") == 0)    //客户端下线时删除该地址
        {
            del_client(L, cli_addr) ;
            printf("offline!!!\n") ;
        }
        //printf("receive from ip : %s, port : %d, message : %s\n", inet_ntoa(cli_addr.sin_addr), ntohs(cli_addr.sin_port), recv_buf) ;    //测试服务器端是否收到消息
        memset(message, 0, 128) ;
        sprintf(message, "from ip : %s, port : %d\nmessage : %s\n",inet_ntoa(cli_addr.sin_addr), ntohs(cli_addr.sin_port), recv_buf) ;    //给message添加发信客户端信息
        //sendto
        p = L ;
        while(p->next != NULL)    //向链表内存储的全部客户端地址发消息
        {
            p = p->next ;
            strcpy(send_buf, message) ;
            sendto(server_fd, send_buf, strlen(send_buf), 0, (struct sockaddr*)&(p->client_addr), sizeof(cli_addr)) ;
        }
    }
    //close
    close(server_fd) ;
    return 0;
}

/* client.c */        //可以有多个客户端同时通过服务器收发消息
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <stdlib.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <pthread.h>
void * thd_handle(void * arg)    //子线程，负责接收消息
{
    int client_fd = *(int*)arg ;
    char recv_buf[128] ;
    struct sockaddr_in server_addr ;
    while(1)
    {
        //recvfrom
        memset(&server_addr, 0, sizeof(server_addr)) ;
        memset(recv_buf, 0, 128) ;
        int len = sizeof(server_addr) ;
        recvfrom(client_fd, recv_buf, 128, 0, (struct sockaddr*)&server_addr, &len) ;
        printf("%s", recv_buf) ;
    }
}
int main(int argc, char * argv[])  // ---> ./exe ip port
{
    int client_fd ;
    pthread_t thd ;
    char send_buf[128] ;
    struct sockaddr_in server_addr;
    //socket
    client_fd = socket(AF_INET, SOCK_DGRAM, 0) ;
    thd = pthread_create(&thd, NULL, thd_handle, (void*)&client_fd) ;    //创建收消息线程
    if(client_fd == -1)
    {
        perror("socket") ;
        exit(-1) ;
    }
    memset(&server_addr, 0, sizeof(server_addr)) ;
    server_addr.sin_family = AF_INET ;
    server_addr.sin_port = htons(atoi(argv[2])) ;
    server_addr.sin_addr.s_addr = inet_addr(argv[1]) ;
    //sendto (online)
    memset(send_buf, 0, 128) ;
    strcpy(send_buf, "online\n") ;
    sendto(client_fd, send_buf, strlen(send_buf), 0, (struct sockaddr*)&server_addr, sizeof(server_addr)) ;    //连接服务器时发送上线信息
    while(1)
    {
        //sendto
        memset(send_buf, 0, 128) ;
        fgets(send_buf, 128, stdin) ;
        sendto(client_fd, send_buf, strlen(send_buf), 0, (struct sockaddr*)&server_addr, sizeof(server_addr)) ;
        if(strcmp(send_buf, "offline\n") == 0)    //发送offline时下线退出
        {
            break ;
        }
    }
    //close
    close(client_fd) ;
    return 0 ;
}