C: getting hostname from TCP and UDP socket?

Question

I'm not really familiar with the connection protocols.

I'm using the following code to examine connect() so I can get the hostname:

#ifndef   NI_MAXHOST
#define   NI_MAXHOST 1025
#endif

int error;

 char hostname[NI_MAXHOST] = "";


 error = getnameinfo(serv_addr, addrlen, hostname, NI_MAXHOST, NULL, 0, 0);

 if (error !=0) {
  ALogTCP(@"coudldn't resolve hostname or internal connect");
  [pool release];
  return orig__connect(sockfd, serv_addr, addrlen);
  }


 if (error == 0) {
  ALogTCP(@"hostname: %s", hostname);
  NSString *hostFirst = [NSString stringWithCString:hostname];
}

can I use the "same" code to get the hostname if I hook into sendto() (so I can examine UDP)?

thanks in advance.

Answer 1

You should be able to do so because sendto() is passed a struct sockaddr just as you are using in your example code.

When you "hook" sendto() I assume you will do so with a macro which affects only your own source code -- as opposed to something like an intermediating driver.

The DNS name resolution depends on sending UDP packets, so if you were to "hook" sendto() at a low enough level, your solution would recurse infinitely as it looked up the hostnames for outgoing DNS lookup packets...