UDP 소켓에소 구조체 보내기....

간단한 udp server 소스입니다...참고하시길...

#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>

#define MYPORT 50009
#define MAXBUFLEN 100

main()
{
	int sockfd;
	struct sockaddr_in my_addr;
	struct sockaddr_in their_addr;
	int addr_len, numbytes;
	char buf[MAXBUFLEN];
	if((sockfd=socket(AF_INET, SOCK_DGRAM,0)) == -1){
		perror("socket");
		exit(1);
	}
	my_addr.sin_family = AF_INET;
	my_addr.sin_port = htons(MYPORT);
	my_addr.sin_addr.s_addr = INADDR_ANY;
	bzero(&(my_addr.sin_zero),8);
	if(bind(sockfd,(struct sockaddr*)&my_addr, sizeof(struct sockaddr))==-1){
		perror("bind");
		exit(1);
	}
	while(1){
		if((numbytes = recvfrom(sockfd, buf, MAXBUFLEN,0,
					(struct sockaddr *)&their_addr, &addr_len)) == -1){
			perror("recvfrom");
			exit(1);
		}
		buf[numbytes]='\0';
		printf("get packet form %s\n", inet_ntoa(their_addr.sin_addr));
		printf("packet is %d bytes long\n", numbytes);
		printf("packet contains :%s\n", buf);
		if(strcmp(buf,"exit\n")==0) break;

		memset(buf,'\0', MAXBUFLEN);
		printf("Input Message: ");
		fflush(stdin);
		fgets(buf, MAXBUFLEN,stdin);
		if((numbytes=sendto(sockfd, buf, strlen(buf),0,
						(struct sockaddr*)&their_addr, sizeof(struct sockaddr)))==-1){
			perror("sendto");
			exit(1);
		}
		if(strcmp(buf,"exit\n")==0) break;
		printf("send %d bytes to %s\n", numbytes, inet_ntoa(their_addr.sin_addr));
		
		
	}
	close(sockfd);
}

이소스를 보면 sockaddr이라는 구조체를 통해 상대방의 ip를 알수가 있죠..
그리고 buf를 잡아서 받고,보내는거구요....