/* A simple server in the internet domain using TCP
   The port number is passed as an argument */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h> 
#include <sys/uio.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <errno.h>

void error(const char *msg)
{
    perror(msg);
    exit(1);
}

int main(int argc, char *argv[])
{
	int sockfd, newsockfd, portno;
	socklen_t clilen;
	struct sockaddr_in serv_addr, cli_addr;
	int n;
	ssize_t recv;
	struct msghdr mh;
	struct iovec iov[1];
	
	char primo[256];
	
	memset(&mh, 0, sizeof(mh));
	memset(iov,  0, sizeof(iov));
	
	/* Specify the components of the message in an "iovec".*/
	iov[0] .iov_base = (caddr_t)primo;			
	iov[0] .iov_len = sizeof(primo);
	
	/*set iov in mh*/
	mh.msg_iov = iov;
	mh.msg_iovlen = sizeof(iov);
	
	printf("Structures initialized \n");

	if (argc < 2) {
	 fprintf(stderr,"ERROR, no port provided\n");
	 exit(1);
	}
	sockfd = socket(AF_INET, SOCK_STREAM, 0);
	if (sockfd < 0) 
		error("ERROR opening socket");
	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);
	if (bind(sockfd, (struct sockaddr *) &serv_addr,
		  sizeof(serv_addr)) < 0) 
		  error("ERROR on binding");		  
	listen(sockfd,500);
	clilen = sizeof(cli_addr);
	newsockfd = accept(sockfd, 
			 (struct sockaddr *) &cli_addr, 
			 &clilen);
	if (newsockfd < 0) 
	  error("ERROR on accept");
	  
	printf("Waiting on recvmsg() \n");
	
	recv = recvmsg(sockfd, &mh, 0);
	if (recv == -1) {
		perror("recvmsg failed ");
		strerror(errno);
		return -1;
	}
	
	n = write(newsockfd,"I got your message",18);
	if (n < 0) error("ERROR writing to socket");
	close(newsockfd);
	close(sockfd);
	return 0; 
}