/*客户端程序UDPClient.c,使用方法UDPClient ServerIP ServerPort*/
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <netdb.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <unistd.h>
#include <sys/socketvar.h>
#include <arpa/inet.h>
#define MAX_BUF_SIZE 1024
/******************************************************
Linux中Socket:
(1) struct sockaddr {
unsigned short sa_family;
char sa_data[14];
}
(2) struct sockaddr_in{
short int sin_family;
unsigned short int sin_port;
struct in_addr sin_addr;
unsigned char sin_zero[8];
};
(3) struct in_addr{
unsigned long s_addr;
};
******************************************************/
void udpc_requ(int sockfd,const struct sockaddr *addr,int len)
{
char buffer[MAX_BUF_SIZE];
int n;
while(1)
{
fgets(buffer,MAX_BUF_SIZE,stdin);
sendto(sockfd,buffer,strlen(buffer),0,addr,len);
bzero(buffer,MAX_BUF_SIZE);
/*从网络上读,写到屏幕上*/
n=recvfrom(sockfd,buffer,MAX_BUF_SIZE,0,NULL,NULL);
buffer[n]=0;
fputs(buffer,stdout);
}
}
int main(int argc,char **argv)
{
int sockfd,port;
struct sockaddr_in *p;
struct sockaddr addr;
if(argc!=3)
{
fprintf(stderr,"Usage:%s server_ip server_port\n",argv[0]);
exit(1);
}
if((port=atoi(argv[2]))<0)
{
fprintf(stderr,"Usage:%s server_ip server_port\n",argv[0]);
exit(1);
}
sockfd=socket(AF_INET,SOCK_DGRAM,0);
if(sockfd<0)
{
fprintf(stderr,"Socket Error:%s\n",strerror(errno));
exit(1);
}
/*填充服务器端的资料*/
bzero(&addr,sizeof(addr));
p=(struct sockaddr_in *)&addr;
p->sin_family=AF_INET;
p->sin_port=htons(port);
if(inet_aton(argv[1],&p->sin_addr)<0)
{
fprintf(stderr,"Ip error:%s\n",strerror(errno));
exit(1);
}
udpc_requ(sockfd,&addr,sizeof(struct sockaddr_in));
close(sockfd);
}
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