#include <stdio.h>
#include <unistd.h>
#include <strings.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>

int main(int argc, char *argv[])
{
	int sockfd, newsockfd, portnum, addr_len;
	char buffer[512];
	struct sockaddr_in server_addr, client_addr;
	int n;

	if (argc < 2) {
		fprintf(stderr, "ERROR: No port provided\n");
		exit(1);
	}

	sockfd = socket(AF_INET, SOCK_STREAM, 0);
	if (sockfd < 0) {
		fprintf(stderr, "ERROR opening socket\n");
		exit(1);
	}

	portnum = atoi(argv[1]);
	server_addr.sin_family = AF_INET;
	server_addr.sin_addr.s_addr = INADDR_ANY;
	server_addr.sin_port = htons(portnum);

	n = bind(sockfd, (struct sockaddr *) &server_addr, sizeof(server_addr));
	if (n<0) {
		fprintf(stderr, "ERROR on binding\n");
		exit(1);
	}

	listen(sockfd, 5);

	addr_len = sizeof(client_addr);
	newsockfd = accept(sockfd, (struct sockaddr *) &client_addr, &addr_len);
	if (newsockfd < 0) {
		fprintf(stderr, "ERROR on accept\n");
		exit(1);
	}

	bzero(buffer, 512);

	n = read(newsockfd, buffer, 511);
	if (n < 0) {
		fprintf(stderr, "ERROR reading from socket\n");
		exit(1);
	}
	fprintf(stdout, "Here is the message: %s\nIt is on port %d\n", buffer, portnum);

	n = write(newsockfd, "I got your message. It was a very nice message.\n", 19);
	if (n < 0) {
		fprintf(stderr, "ERROR writing to socket\n");
		exit(1);
	}

	return 0;
}