Re: [9fans] csipinfo

[Joel “chesky” Salomon <chesky@plan9.jp>]

> had to go around the list ... can't post from here.
> 
> i think you're making this too hard.  what you want is more
> of a dns query.  this is very easy to do.  something like
> (this might not complie -- i just typed it out.)
> 
> char*
> gethostbyaddr(char *net, char *addr)
> {
> 	char buf[64];
> 	int fd, l;
> 
> 	if(net == 0)
> 		net="/net";
> 	snprint(buf, sizeof buf, "%s/dns", net);
> 	fd = open(buf, ORDWR);
> 	if(fd < 0)
> 		return 0;
> 	snprint(buf, sizeof buf, "%s ptr", addr);
> 	if(write(fd, buf, strlen(buf)) < 0)
> 		return 0;
> 	l = read(fd, buf, sizeof buf);
> 	if(l < 0 || l == sizeof buf)
> 		return 0;
> 	return strdup(buf);
> }
> 
> - erik

Thanks, this finally looks like what I need.  Two points though:
1.  Is 64 bytes sufficient for the domain name?  Searching the ’net
I’ve found other numbers — according to <http://tinyurl.com/ykyths> it
should be 1005; <http://tinyurl.com/xdp4> links to a name about 140
bytes long and firefox handles it just fine.
2. Why the second part of “if(l < 0 || l == sizeof buf)”?

I’ll bang on this a bit and see if I can make it set errstr appropriately.

--Joel