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I'm currently working on a "list what's up in the local network"-tool and now i'm stuck at the "gimme a hostname for this IP"-part.

I already tried getnameinfo and gethostbyaddr, but the first one returns (almost) always the given IP instead of a hostname, the second one returns some strange stuff like ANantes-651-1-49-net.w2-0.abo.wanadoo.fr...

My question is: How could i make this work?

Note: It's not like there is no hostname associated with at least one of the IPs, for example dig +short -x 192.168.178.1 return fritz.box. as it should and also host 192.168.178.1 gives the correct answer 1.178.168.192.in-addr.arpa domain name pointer fritz.box.

Additional note: On my research i stumbled upon a library, called "adns", but by "stumbled upon" i mean "almost literally stumbled upon", as there's not the slightest trace of a documentation, examples or such... So if someone actually has an example on how to use "adns", that would be great...

user3128045
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  • Can you show how you're setting the address used as argument to `gethostbyaddr()`? You realize that this "ANantes-651-1-49-net.w2-0.abo.wanadoo.fr" resolves to 2.0.0.0, and vice-versa, don't you. So there's a chance that your arguments might be faulty. – Paulo1205 Feb 19 '16 at 21:21
  • `... sockaddr_in address; memset(&address, 0, sizeof(address)); address.sin_family = AF_INET; address.sin_addr.s_addr = inet_addr("192.168.178.1"); struct hostent *h =gethostbyaddr((const void *)&address, sizeof(address), AF_INET); ...` – user3128045 Feb 19 '16 at 22:25
  • Dang... How do i use line-breaks in comments? And yep, i checked the "hostname" with `dig` and saw this weird `2.0.0.0`... – user3128045 Feb 19 '16 at 22:27

1 Answers1

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Oookay... Seems, like i screwed up several things in an almost "monkey wanna banana"-style...

No.1:

I used this:

...
sockaddr_in address;
memset(&address, 0, sizeof(address));
address.sin_family = AF_INET;
address.sin_addr.s_addr = inet_addr("192.168.178.1");
struct hostent *h =gethostbyaddr((const void *)&address, sizeof(address), AF_INET);
...

Instead of the correct:

...
in_addr address;
inet_aton("192.168.178.1",&address);
struct hostent *h = gethostbyaddr((const void *)&address, sizeof(address), AF_INET);
...

No.2:

I had a line where i checked, if the returned hostname was empty to replace it with a placeholder, depending on the selected "report format" (plain text/xml/csv). But for whatever reason, i wrote it in a way, that it ALWAYS replaced the hostname with the said placeholder (dang! it was kinda obvious, but i didn't see it the whole time...).

BUT FINALLY: YAY! It works...

user3128045
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