/* this is a UDP sender */

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

int main(int argc, char *argv[])
{
	int sockfd;
	// struct sockaddr_in servaddr, saddr1;
	struct sockaddr_in servaddr;
	char buf, buf1;
	// int len;

	if (argc < 3) {
		printf("Usage : a.out IPaddr port\n");
		exit(0);
	}

	memset(&servaddr, 0, sizeof(servaddr));  
	servaddr.sin_family = AF_INET;
	servaddr.sin_port = htons((int)atoi(argv[2]));
	servaddr.sin_addr.s_addr = inet_addr(argv[1]);

	if ((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
		perror(": socket");
		exit(0);
	}

	{ 
		/* basic algorithm not reliability here */
		int i;
		buf = 'A';
		for (i=0; i< 1000; i++) {
			sendto(sockfd, &buf, 1, 0, (struct sockaddr *)&servaddr, 
					sizeof(servaddr));
			buf++;
			if (buf == 'Z'+1) buf = 'A';
			recvfrom(sockfd, &buf1, 1, 0, NULL, NULL);
			printf("got ack i= %d\n", i);
		}



		sleep(3);
		for (i=0; i<4; i++) {
			buf = '+';
			sendto(sockfd, &buf, 1, 0, (struct sockaddr *)&servaddr, 
					sizeof(servaddr));
			sleep(2);
		}
	}



}