cpp connect() function is blocked indefinitely - c++

Question

#include <sys/socket.h>
#include <cstdio>
#include <stdlib.h>
#include <iostream>
#include <errno.h>
#include <sys/types.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <netdb.h>
#include <unistd.h>
#define BUFSIZE 5000
#define PORT 80
using namespace std;
int main(int argc, char* argv[]){
char buffer[BUFSIZE];
int sockfd;
struct sockaddr_in their_addr;
if((sockfd = socket(PF_INET, SOCK_STREAM, 0)) == -1){
perror("Socket generating failed");
exit(1);
}
their_addr.sin_family = AF_INET;
their_addr.sin_port = htons(PORT);
their_addr.sin_addr.s_addr = htonl(((struct in_addr*)gethostbyname("www.google.com")->h_addr_list[0])->s_addr);
if(connect(sockfd, (struct sockaddr*)&their_addr, sizeof(struct sockaddr)) == -1){ // stops at here!
perror("Connection failed");
exit(1);
}
close(sockfd);
return 0;
As a test of a combination of gethostbyname + connect, I wrote a simple code.
It queries the IP address of google by means of gethostbyname(), connects to google do nothing, and close the socket.
However, the program just stops at a line of the connect() function without any error including perror().
How can I fix this?

Answer 1

Get the s_addr, make sure it is an ipv4 address, and then on the command line try to ping that address with the command 'ping addr'
After that you could try a program like nmap but most likely ping will be enough.
There is probably nothing wrong with your code. You need to see if there is a proxy or firewall or anything else interfering with your network connection. You will also want to confirm you are getting an ipv4 address with gethostbyname

Answer 2

I solved this problem by removing htonl. I don't know why, and what could happen in future as a result of removing it. But this would be my best.

Answer 3

The socket API is not part of C++, it is posix. gethostbyname()is obsolete, use getaddrinfo instead. Read the appropriate man page, it also contains as example precisely the code you look for...