#include <stdio.h> 
#include <stdlib.h> 
#include <string.h> 
#include <sys/socket.h> 
#include <netinet/in.h>
#include <unistd.h>
void error(char *msg)  {
	//tato funkcia sa vyuziva ked systemove volanie zlyha     
	perror(msg); //vypise spravu o chybe a ukonci program server     
	exit(1); 
} 
int main(int argc, char *argv[]) {      
	int sockfd, newsockfd, portno, clilen, n; //pomocne premenne      
	char buffer[256];         //buffer pre ulozenie znakov zo socketu      
	struct sockaddr_in serv_addr; //obsahuje adresu servera      
	struct sockaddr_in cli_addr;  //obsahuje adresu klienta      
	if (argc < 2) {                //kontrola poctu argumentov          
		fprintf(stderr,"ERROR, no port provided\n");          
		exit(1);      
	}                                     //vytvorenie socketu      
	sockfd = socket(PF_INET, SOCK_STREAM, 0);      
	if (sockfd < 0) 
		error("ERROR opening socket");                                     //naplnenie struktury sockaddr_in       
	bzero((char *) &serv_addr, sizeof(serv_addr));      
	portno = atoi(argv[1]);      
	serv_addr.sin_family = AF_INET;      
	serv_addr.sin_addr.s_addr = INADDR_ANY;      
	serv_addr.sin_port = htons(portno);                                     //zviazanie socketu sluzbou bind()      
	//printf("%s", hostent->h_name);
	if (bind(sockfd, (struct sockaddr *) &serv_addr,                  
				sizeof(serv_addr)) < 0)                
				error("ERROR on binding");      
	listen(sockfd,5);              //vytvorime si front poziadaviek      
	clilen = sizeof(cli_addr);     //velkost struktury adresy klienta                                     //akceptovanie spojenia      
	newsockfd = accept(sockfd,(struct sockaddr *) &cli_addr,&clilen);      
	if (newsockfd < 0) 
		error("ERROR on accept");      
	bzero(buffer,256);             //spracovanie dat od klientov      
	n = read(newsockfd,buffer,255);      
	if (n < 0) 
		error("ERROR reading from socket");      
	printf("Here is the message: %s\n",buffer);      
	n = write(newsockfd,"I got your message",18);      
	if (n < 0) 
		error("ERROR writing to socket");      
	return 0;  
}