[jdev] Re: SOCKS5 Bytestream File Transfer problem

[Anthony Ortiz]

Hello everyone!

It seems that I may be confusing this issue, so let me see if I have
everything straight :

My understanding is that the SOCKS(5) server acts as a firewall
between a host and a client. In order for a client to reach the host,
it must authenticate with the SOCKS(5) server which is in essence a
proxy. The SOCKS(5) server in turn then forwards the data to the
actual host. The following is a diagram of what I think is going on :

client ---- SOCKS(5) server [aka. proxy] --- host

If my understanding is correct, then I must assume that a barebones
SOCKS(5) library *MUST* include a connection mechanism in which they
must specify both a proxy AND a host address as such [in pseudo code]
:

SetSOCKS5Proxy(proxy_ip, proxy_port)
s = OpenSOCKS5Socket(host_ip, host_port)

In this particular case, where a jabber bytstream file transfer occurs
as detailed in http://www.jabber.org/jeps/jep-0065.html#proto-establish,
I see this as being the case :

client [aka. file xfer receiver] ---- internet --- SOCKS(5) server
[aka. proxy] --- host [aka. file xfer initiator]

Now, here is where I am running into trouble... The JEP-0065 seems to
indicate that the host is a SHA-1 hash of the sid + initiator_jid +
target_jid. I would assume such a host would not exist, but that's
what the protocol says to do, so I go with it. Given the following
actual data, I get a UnknownHost exception (and I am going by the
book!) :

** INITIATOR TO RECEIVER **
<iq xmlns='jabber:client' type='set' to='aortiz at 68.101.84.233/JClient'
id='aad5a' from='venkata at 68.101.84.233/Psi'>
 <query xmlns='http://jabber.org/protocol/bytestreams' mode='tcp'
sid='s5b_9490b8d451352325'>
  <streamhost xmlns='http://jabber.org/protocol/bytestreams'
port='8010' host='192.168.1.100' jid='venkata at 68.101.84.233/Psi'/>
   <fast xmlns='http://affinix.com/jabber/stream'/>
  </query>
</iq>
*** END ***

sid = "s5b_9490b8d451352325'"

// note : the following jid's have been nodeprepped + "@" +
nameprepped + "/" + resourceprepped... turns out that in this case the
result jid's are the same as the originals.

initiator_jid = "venkata at 68.101.84.233/Psi"
target_jid = "aortiz at 68.101.84.233/JClient"

proxy_host = "192.168.1.100"
proxy_port = 8010

host = SHA1(sid + initiator_jid + target_jid) // resulting HASH =
"863965e5a89fed0b9aeeab809733b3ef234aa835"
port = 0

Given the above data, the diagram should look as follows :

client [aka. file xfer receiver] ---- internet --- SOCKS5 PROXY
[192.168.1.100:8010] --- host
[863965e5a89fed0b9aeeab809733b3ef234aa835:0]

Therefore, I must issue the following calls to the SOCKS5 library in
order to establish the connection [pseudo_code] :

SetSOCKS5Proxy("192.168.1.100", 8010)
s = OpenSOCKS5Socket("863965e5a89fed0b9aeeab809733b3ef234aa835", 0)

The OpenSOCKS5Socket call does exactly what the JEP-0065 protocol
describes... that is, it sends the following :

** REQUEST PACKET **
CMD = X'01'
ATYP = X'03'
DST.ADDR = "863965e5a89fed0b9aeeab809733b3ef234aa835"
DST.PORT = 0
** END **

Yet, this results in an exception error!!! :(

I have also implemented a straight SOCKS5 connection to
192.168.1.100:8010 and (upon successfull connection) manually sending
that request packet as the protocol describes, but I get 9 bytes of
0's as a result, which indicates an error of some sort.

Can anyone shed some light on the matter???

Thanks!

Anthony