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Re: No Data error connecting with hidden services

Hi Dashiell,

I found the 'No data' problem, when accessing hidden services, to be 
as you suggested. The internet controls QS uses do a dns lookup in 
socks level 4a. Then it passed the the ip address to Tor in the same 
manner as if it had not done the lookup itself.

Fortunately, it took a grand total of 6 lines of code to fix the 
problem! In the dns lookup function, there was a small section 
devoted to bailing out of the lookup if the hostname specified was 
actually a dotted ip address. Using this as a model, I set the 
dnsresult to the hostname and bailed out in the same manner. That has 
done the trick nicely!

I'm puzzled about the implementation of 4a in the socket code. I know 
you said many programs do this. It looks to me like this is not only 
incorrect but completely defeats the purpose of level 4a. If QS fails 
the dns lookup then it never gets to the point of passing anything to 
Tor. Is that correct? Is this worthy of telling the author of the 
controls about it?

Thank you so much for your assistance. On reading your reply to me it 
is apparent that you took the time to scout out my website and even 
go through my betas mailing list to come up to speed on where QS is 
in relation to Tor. It was very generous use of your time and I 
appreciate your efforts. I'm glad I joined this list and have 
somewhere to go with my questions. I imagine I will have more!


On Wed, 22 Dec 2004 21:21:16 -0500, you wrote:
> > Hi,
> >
> > I hope this is the right place to ask my question.
> >
> > I have added socks proxy support to my remailer client QuickSilver. I
> > find I can connect and use Tor for various protocols (SMTP, HTTP,
> > FTP, NNTP, POP3) without problems. However, when I try to connect
> > with a hidden service, for example panta remailer's service
> > rjgcfnw4sd2jaqfu.onion, I get an immediate 'No Data' error. I expect
> > this is a problem with my email client, but I have no idea what to
> > look into to correct it. If anyone could shed some light on this I
> > would be very appreciative.
> >
> > Thanks,
> >
> > Richard
> > --
> > Richard Christman
> > http://quicksilvermail.net
> >
> The main cause of problems with connecting to hidden services is
> when the application looks up the hostname and provide the ip to the
> socks server instead. An .onion address isn't real and can't be
> resolved so this is where errors happen.
> I've come across many applications that say they support Socks 4A
> but in fact still end up looking up the hostname and passing an ip
> instead.
> I understand that Quicksilver uses a third party "internet controls"
> which provides the socks support. Grab a free packet sniffer like
> Ethereal and double check to make sure that this library isn't doing
> that.
> I also saw on your list an error message posted:
> Dec 06 15:08:12.484 [warn] No Tor server exists that allows exit to
> Rejecting.
> Tor actually provides the hostname instead of the ip when giving
> these errors, if it's been given a hostname. Perhaps the user
> specifically used the ip instead of "mail.dingoremailer.com", but it
> seems that your internet toolkit might possibly be looking up
> hostnames itself instead of passing them to the socks server
> If I'm completely wrong and barking up the wrong tree, the next
> thing to do is get a far more detailed report from Tor about what's
> happening. Adding the line:
> Log debug file debug.txt
> to your torrc will get tor to spew out an incredibly detailed log to
> debug.txt which will explain any reasons for a socks connection not
> completing. Posting it here might enable people to see what the
> problem is, as there's not too much to go on right now.
> Sorry I couldn't be of much help.

Richard Christman