C / C++ / MFC Discussion Boards

Problems with sending UPD Packets over sendto

CrazyDogg11-Jan-09 23:59

11-Jan-09 23:59

Hi @ all,

under XP I have the problem sending UDP Packets over the sendto command.

Sporadically my client didn´t send the packets.

The first time it works fine. I build the packet and then send it with the sendto command. On the second time or more the packet will be created and runs the send command correct. The Remote Port and Address are correct too.

But if I protocol these actions with packetyzer or wireshark the sent packet is not displayed anywhere.

Anyone here who knows what it could be that the packet will not send?

Regards,

Karsten

Re: Problems with sending UPD Packets over sendto

Rajkumar R12-Jan-09 0:08

Rajkumar R

12-Jan-09 0:08

Check the return value of sendto API

Re: Problems with sending UPD Packets over sendto

CrazyDogg12-Jan-09 0:17

CrazyDogg

12-Jan-09 0:17

the return Value is above Zero and the size of command.

Re: Problems with sending UPD Packets over sendto

Stuart Dootson12-Jan-09 0:11

Stuart Dootson

12-Jan-09 0:11

UDP will drop packets if you send them too fast - here's a Microsoft article that says as much[^].

Fundamentally, UDP makes no delivery guarantees, so if that's important to you, you either want to think about using TCP (that'd be my choice) or implementing some form of handshaking.

I would recommend downloading the IBM TCP/IP Redbook[^] - it's a very useful networking resource.

Re: Problems with sending UPD Packets over sendto

CrazyDogg12-Jan-09 0:18

CrazyDogg

12-Jan-09 0:18

But under Vista it works correctly.
And I send SIP Packets above the UDP Socket.
I can´t use TCP because it´s a realtime ip phone I programm.

Re: Problems with sending UPD Packets over sendto

David Crow12-Jan-09 3:11

David Crow

12-Jan-09 3:11

CrazyDogg wrote:
But under Vista it works correctly.

Which means it's likely a coincidence.

CrazyDogg wrote:
I can´t use TCP because it´s a realtime ip phone I programm.

Then it'll be up to you to code the handshaking.

"Love people and use things, not love things and use people." - Unknown

"The brick walls are there for a reason...to stop the people who don't want it badly enough." - Randy Pausch

Re: Problems with sending UPD Packets over sendto

CrazyDogg12-Jan-09 3:41

CrazyDogg

12-Jan-09 3:41

How to code a handshaking for this?
I have never done this.

Re: Problems with sending UPD Packets over sendto

David Crow12-Jan-09 3:45

David Crow

12-Jan-09 3:45

CrazyDogg wrote:
How to code a handshaking for this?

However you want to. It's just extra information (usually a CRC) that the send adds to the packet at a specific location (e.g., front, back). The receiver looks at that spot to know if all of the packet has been received. If so, an ACK of some sort is sent back.

"Love people and use things, not love things and use people." - Unknown

"The brick walls are there for a reason...to stop the people who don't want it badly enough." - Randy Pausch

Re: Problems with sending UPD Packets over sendto

CrazyDogg12-Jan-09 3:48

CrazyDogg

12-Jan-09 3:48

I think it is impossible to made a handshake for this because I just code the client.
The server is an asterisk server and I have no rights to change anything.

Why does ConnectEx need a bound socket?

followait11-Jan-09 23:32

followait

11-Jan-09 23:32

In the book, it says:

the socket passed into ConnectEx needs to be previously bound with a call to bind.

Why does a client socket need binding?

Re: Why does ConnectEx need a bound socket?

Stuart Dootson12-Jan-09 0:01

Stuart Dootson

12-Jan-09 0:01

Ummm - because that's the way the API works?

A socket is a communications endpoint - it needs an address (IP address and port number) before it can be used. For a client, the address is 'localhost' (or 127.0.0.1), whilte the port .

The Microsoft samples I've seen use the connect function rather than ConnectEx. connect doesn't require a bound socket - a bind (I would imagine) to an arbitrary port on localhost occurs within connect. ConnectEx gives a significant amount of flexibility in comparison - and (part of) the price for that would appear to be that you have to do the socket binding yourself.

Save an image using CImage class

VC++Maniac11-Jan-09 23:02

VC++Maniac

11-Jan-09 23:02

Im unable to save a image using CImage. Im able to load and draw it. At a later stage, I need to save it to a different path, so I call Save(). It gives an error '80004005' "Unspecified error".

Please suggest..
TIA

Re: Save an image using CImage class

CPallini11-Jan-09 23:43

CPallini

11-Jan-09 23:43

The debugger is your best friend.
Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

[My articles]

Re: Save an image using CImage class

VC++Maniac12-Jan-09 0:10

VC++Maniac

12-Jan-09 0:10

Just now I tried the microsoft's sample. It also gives the same error.. I have nothing to debug. The HRESULT from save is E_FAIL. thats it. the file name is valid. I also tried giving it a simple path name such as "D:\\myImg", but the same error occurs.

TIA

Re: Save an image using CImage class

Code-o-mat12-Jan-09 0:47

Code-o-mat

12-Jan-09 0:47

Does GdiplusStartup succeed?

> The problem with computers is that they do what you tell them to do and not what you want them to do. <

Re: Save an image using CImage class

CPallini12-Jan-09 0:47

CPallini

12-Jan-09 0:47

Could please post your code?
Smile | :)

Re: Save an image using CImage class

Hamid_RT12-Jan-09 1:04

Hamid_RT

12-Jan-09 1:04

CPallini wrote:
Could please post your code?

Hi Pallini. Big Grin | :-D

Yeah but full code ?

Of one Essence is the human race
thus has Creation put the base
One Limb impacted is sufficient
For all Others to feel the Mace
(Saadi )

Re: Save an image using CImage class

CPallini12-Jan-09 1:33

CPallini

12-Jan-09 1:33

Nope. Just the relevant one.
Big Grin | :-D

Re: Save an image using CImage class

VC++Maniac12-Jan-09 1:54

VC++Maniac

12-Jan-09 1:54

I changed my code to use Image class.

I still have the same problem.
I open a image file. then try to save it in png format.
Save fuction returns "Win32Error" status.

GdiplusStartup is successful.

What may be wrong?

Re: Save an image using CImage class

Hamid_RT12-Jan-09 1:56

Hamid_RT

12-Jan-09 1:56

Can you show your code did you attach hbitmap handle to CImage class?

Of one Essence is the human race
thus has Creation put the base
One Limb impacted is sufficient
For all Others to feel the Mace
(Saadi )

Re: Save an image using CImage class

VC++Maniac12-Jan-09 2:18

VC++Maniac

12-Jan-09 2:18

Another thing I noted is that if I give only the filename.jpg or png, it saves successfully, but if I give the whole path it fails with Win32Error.

Re: Save an image using CImage class

Hamid_RT12-Jan-09 2:23

Hamid_RT

12-Jan-09 2:23

When you use of filename.jpg it uses of current directory so I think your problem is of path.

Of one Essence is the human race
thus has Creation put the base
One Limb impacted is sufficient
For all Others to feel the Mace
(Saadi )

Re: Save an image using CImage class

Mark Salsbery12-Jan-09 7:19

Mark Salsbery

12-Jan-09 7:19

Then probably either the path doesn't exist or you don't have sufficient rights to write to the path.

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: Save an image using CImage class

VC++Maniac12-Jan-09 17:18

VC++Maniac

12-Jan-09 17:18

I have given "D:\\123\\123.png" as the path. The path exists and I have full control of the folder.

Re: Save an image using CImage class

Mark Salsbery12-Jan-09 17:46

Mark Salsbery

12-Jan-09 17:46

If you step into the Save method in the debugger, where is the error occurring?

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

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