WTSVirtualChannelRead does not read anything

[Guest Roman Divacky]

hi

 

I am trying to read some data from a virtual channel using

WTSVirtualChannelRead() but it reads nothing.

When I try to write to the channel it goes just fine but reading is no

go :(

 

The client in question is "rdesktop" so I am quite sure the client is

ok, but my app does not recieve anything from the channel. And yes, I

put some debuging into the rdesktop to see if it really puts something

on the wire.

 

When I try to use WTSVirtualChannelQuery() to obtain file handle and

ReadFile/WriteFile from/to it nothing works at all (nor reading nor

writing).

 

plain

 

HANDLE foo = WTSVirtualChannelOpen(WTS_CURRENT_SERVER_HANDLE,

SessionId, "rdpsnd");

WTSVirtualChannelRead(foo, INFINITY, buf, buf_size, &len);

 

never returns and when I change the INFINITY to something lower it

returns with 0 bytes read.

 

does anyone have any comment or an example of working code with

WTSVirtualChannelRead(). I must be doing something bad but I am not

able to figure out what :(

 

thnx a lot in advance

 

Roman Divacky

[Guest ThomasT.]

Re: WTSVirtualChannelRead does not read anything

 

From where you can be sure that the rdesktop client supports Virtual Channel

?

I'm not sure that it has this feature implemented (have seen this question a

while ago).

 

If you use MS RDP Client the virtual channel communication is always

initialized

on the server, 1 round trip looks like this:

 

Server -> Sends something -> Client

Client -> Receives message

Client -> Sends something back to Server

Server Reads from Virtual Channel .

 

Thomas T.

 

"Roman Divacky" <rdivacky@mzm.cz> wrote in message

news:a0eeba60-cbc0-4b41-9e96-8dd1b7d4c41f@v23g2000pro.googlegroups.com...

> hi

>

> I am trying to read some data from a virtual channel using

> WTSVirtualChannelRead() but it reads nothing.

> When I try to write to the channel it goes just fine but reading is no

> go :(

>

> The client in question is "rdesktop" so I am quite sure the client is

> ok, but my app does not recieve anything from the channel. And yes, I

> put some debuging into the rdesktop to see if it really puts something

> on the wire.

>

> When I try to use WTSVirtualChannelQuery() to obtain file handle and

> ReadFile/WriteFile from/to it nothing works at all (nor reading nor

> writing).

>

> plain

>

> HANDLE foo = WTSVirtualChannelOpen(WTS_CURRENT_SERVER_HANDLE,

> SessionId, "rdpsnd");

> WTSVirtualChannelRead(foo, INFINITY, buf, buf_size, &len);

>

> never returns and when I change the INFINITY to something lower it

> returns with 0 bytes read.

>

> does anyone have any comment or an example of working code with

> WTSVirtualChannelRead(). I must be doing something bad but I am not

> able to figure out what :(

>

> thnx a lot in advance

>

> Roman Divacky

[Guest Roman Divacky]

Re: WTSVirtualChannelRead does not read anything

 

On Apr 21, 7:49 pm, "ThomasT." <Thom...@nospam.nospam> wrote:

> From where you can be sure that the rdesktop client supports Virtual Channel

> ?

> I'm not sure that it has this feature implemented (have seen this question a

> while ago).

 

it sends so called completion packet to the server so I guess the

server is supposed

to receive something. And yes, it supports virtual channels, it

initializes for example

the "rdpsnd" virtual channe....

> If you use MS RDP Client the virtual channel communication is always

> initialized

> on the server, 1 round trip looks like this:

>

> Server -> Sends something -> Client

> Client -> Receives message

> Client -> Sends something back to Server

> Server Reads from Virtual Channel .

 

yeah.. I initialize it on the server, send something to the client and

then I want

to read something back but nothing's there. I googled and it looks

like other

people had this problem too...