Poll TCP socket idle listen - c++

Question

I am sorry if the title is misleading. I cannot really think of a better one. Here is some simple socket program that I have:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <sys/poll.h>
#include <iostream>
#define BACKLOG 10
void error(const char *msg)
{
perror(msg);
exit(1);
}
int main(int argc, char *argv[])
{
if (argc < 2) {
fprintf(stderr,"ERROR, no port provided\n");
exit(1);
}
int sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd < 0)
error("ERROR opening socket");
struct sockaddr_in serv_addr;
bzero((char *) &serv_addr, sizeof(serv_addr));
int portno = atoi(argv[1]);
serv_addr.sin_family = AF_INET;
serv_addr.sin_addr.s_addr = INADDR_ANY;
serv_addr.sin_port = htons(portno);
auto bindsuccess = bind(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr));
if (bindsuccess < 0)
error("ERROR on binding");
struct pollfd newPollFD[1];
newPollFD[0].fd = sockfd;
newPollFD[0].events = POLLIN;
char buffer[256];
bzero(buffer,256);
listen(sockfd, BACKLOG);
struct sockaddr_in cli_addr;
socklen_t clilen = sizeof(cli_addr);
int newsockfd;
int rv = poll(newPollFD, 1, -1);
if (rv == -1) {
error("Error occured in Poll");
}
else {
if (newPollFD[0].revents & POLLIN){
newsockfd = accept(sockfd, (struct sockaddr *) &cli_addr, &clilen);
if (newsockfd < 0)
error("ERROR on accept");
int rwsuccess;
rwsuccess = read(newsockfd,buffer,255);
if (rwsuccess < 0)
error("ERROR reading from socket");
printf("Here is the message: %s\n",buffer);
rwsuccess = write(newsockfd,"I got your message \n",18);
if (rwsuccess < 0)
error("ERROR writing to socket");
}
}
close(newsockfd);
close(sockfd);
return 0;
}
If I execute this code with a port number, and then telnet to that port number, the server listens in, but as soon as I send my first message, the connection terminates. I want the sever to keep on listening and sending acknowledgement back as many times as I send message from telnet. How do I accomplish that?
Thanks in advance!

Answer 1

The continue is curiously extraneous, and causes the compilation to break. (It is now corrected in your edit.) But, you are missing a for loop. And, you should add a check if the read returns 0.
for (;;) {
int rwsuccess;
rwsuccess = read(newsockfd,buffer,255);
if (rwsuccess < 0)
error("ERROR reading from socket");
if (rwsuccess == 0) break;
printf("Here is the message: %s\n",buffer);
rwsuccess = write(newsockfd,"I got your message \n",18);
if (rwsuccess < 0)
error("ERROR writing to socket");
}