network_programming/mid at master · rlarkdms/network_programming · GitHub

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Script started on 2020년 10월 22일 (목) 오전 09시 36분 25초
[?1034hnetpa15@~/ 567$ catt[K prog.[K/mid_daytime.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <netdb.h>
#include <errno.h>


#define MAXLINE 511

int main(int argc, char *argv[]){
struct sockaddr_in servaddr;
int s,nbyte,addrlen=sizeof(servaddr);
int i;
char buf[MAXLINE+1];
struct hostent *hp;
struct in_addr in;
char buf1[MAXLINE+1];

if (argc !=3){
printf("Usage: %s hostname\n",argv[0]);
exit(0);
}

if((s=socket(PF_INET,SOCK_DGRAM,0))<0){
perror("socket fail");
exit(1);
}

hp=gethostbyname(argv[1]);

bzero((char*)&servaddr,sizeof(servaddr));
servaddr.sin_family=AF_INET;
for(i=0; hp->h_addr_list[i]; i++){
memcpy(&in.s_addr,hp->h_addr_list[i],sizeof(in.s_addr));
inet_ntop(AF_INET, &in,buf1,sizeof(buf));
}
inet_pton(AF_INET,buf1,&servaddr.sin_addr);
servaddr.sin_port=htons(atoi(argv[2]));


if(sendto(s,buf,strlen(buf),0,(struct sockaddr *)&servaddr,addrlen)<0){
perror("sendto fail");
exit(0);
}


if((nbyte=recvfrom(s,buf,MAXLINE,0,(struct sockaddr*)&servaddr, &addrlen))<0){
perror("recevfrom fail");
exit(0);
}

buf[nbyte]=0;
printf("%s",buf);
close(s);
return 0;

}
netpa15@~/ 568$ prof[Kg/mid_daytime css.skuniv.ac.kr 9999
Thu Oct 22 09:36:58 2020
netpa15@~/ 569$ exit

Script done on 2020년 10월 22일 (목) 오전 09시 37분 03초