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

#define MAX_BUF 100

int main(int argc, char* argv[])
{
	int sockd;
	struct sockaddr_in my_addr, srv_addr;
	char buf[MAX_BUF];
	int count;
	int addrlen;

	if (argc < 3)
	{
		fprintf(stderr, "Usage: %s ip_address port_number\n", argv[0]);
		exit(1);
	}
	/* create a socket */
	sockd = socket(AF_INET, SOCK_DGRAM, 0);
	if (sockd == -1)
	{
		perror("Socket creation error");
		exit(1);
	}

	/* client address */
	my_addr.sin_family = AF_INET;
	my_addr.sin_addr.s_addr = INADDR_ANY;
	my_addr.sin_port = 0;

	bind(sockd, (struct sockaddr*)&my_addr, sizeof(my_addr));

	strcpy(buf, "Hello world\n");

	/* server address */ 
	srv_addr.sin_family = AF_INET;
	inet_aton(argv[1], &srv_addr.sin_addr);
	srv_addr.sin_port = htons(atoi(argv[2]));

	sendto(sockd, buf, strlen(buf)+1, 0, 
			(struct sockaddr*)&srv_addr, sizeof(srv_addr));

	addrlen = sizeof(srv_addr);
	count = recvfrom(sockd, buf, MAX_BUF, 0, 
			(struct sockaddr*)&srv_addr, &addrlen);
	write(1, buf, count);

	close(sockd);
	return 0;
}