udp_client.c udp_server.c

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

#define SERVER_PORT 8888
#define MAX_BUF_SIZE 1024 

void udpc_requ(int sockfd,const struct sockaddr_in *addr,int len)
{
    char buffer[MAX_BUF_SIZE];
    int n;
    while(1)
    {     /* 从键盘读入,写到服务端 */
        printf("Please input char:\n");
        fgets(buffer,MAX_BUF_SIZE,stdin);
        sendto(sockfd,buffer,strlen(buffer),0,(struct sockaddr *)addr,len);
        bzero(buffer,MAX_BUF_SIZE);
    }
} 

int main(int argc,char **argv)
{
    int sockfd;
    struct sockaddr_in addr; 

    if(argc!=2)
    {
        fprintf(stderr,"Usage:%s server_ip\n",argv[0]);
        exit(1);
    }

    /* 建立 sockfd描述符 */
    sockfd=socket(AF_INET,SOCK_DGRAM,0);
    if(sockfd<0)
    {
        fprintf(stderr,"Socket Error:%s\n",strerror(errno));
        exit(1);
    } 

    /* 填充服务端的资料 */
    bzero(&addr,sizeof(struct sockaddr_in));
    addr.sin_family=AF_INET;
    addr.sin_port=htons(SERVER_PORT);
    if(inet_aton(argv[1],&addr.sin_addr)<0)  /*inet_aton函数用于把字符串型的IP地址转化成网络2进制数字*/
    {
        fprintf(stderr,"Ip error:%s\n",strerror(errno));
        exit(1);
    } 

    udpc_requ(sockfd,&addr,sizeof(struct sockaddr_in)); // 进行读写操作
    close(sockfd);
} 

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

#define SERVER_PORT 8888
#define MAX_MSG_SIZE 1024 

void udps_respon(int sockfd)
{
    struct sockaddr_in addr;
    int addrlen,n;
    char msg[MAX_MSG_SIZE]; 

    while(1)
    {    /* 从网络上读,并写到网络上 */
        bzero(msg,sizeof(msg)); // 初始化,清零
        addrlen = sizeof(struct sockaddr);
        n=recvfrom(sockfd,msg,MAX_MSG_SIZE,0,(struct sockaddr*)&addr,&addrlen); // 从客户端接收消息
        msg[n]=0;//将收到的字符串尾端添加上字符串结束标志
        /* 显示服务端已经收到了信息 */
        fprintf(stdout,"Server have received %s",msg); // 显示消息
    }
} 

int main(void)
{
    int sockfd;
    struct sockaddr_in addr; 

    /* 服务器端开始建立socket描述符 */
    sockfd=socket(AF_INET,SOCK_DGRAM,0);
    if(sockfd<0)
    {
        fprintf(stderr,"Socket Error:%s\n",strerror(errno));
        exit(1);
    } 

    /* 服务器端填充 sockaddr结构 */
    bzero(&addr,sizeof(struct sockaddr_in));
    addr.sin_family=AF_INET;
    addr.sin_addr.s_addr=htonl(INADDR_ANY);
    addr.sin_port=htons(SERVER_PORT); 

    /* 捆绑sockfd描述符 */
    if(bind(sockfd,(struct sockaddr *)&addr,sizeof(struct sockaddr_in))<0)
    {
        fprintf(stderr,"Bind Error:%s\n",strerror(errno));
        exit(1);
    } 

    udps_respon(sockfd); // 进行读写操作
    close(sockfd);
}