[Spread-users] Increasing MAX_GROUP_NAME leads to message header corruption?

Sebastian Wrede swrede at techfak.uni-bielefeld.de
Sun Apr 27 12:11:51 EDT 2008


in order to allow for URIs that map to group names with a length that is
significantly longer than 32 characters, we encode these as MD5 hashes. 

In order to do so, we increased the value of MAX_GROUP_NAME by 1 to 33
characters because it seems that in the default of 32 chars the zero
termination symbol is included. Because spuser now allows us to join,
send to and receive messages from an "MD5" group, which it did not
before this modification I assume the zero termination assumption is
correct, isn't it?

The issue now is that once we change the group length in
SpreadConnection.java to 33 characters, too, it is not possible to send
any longer any messages from a java client to the spread daemon. As soon
as the message is written to the socket, an exception (broken pipe) is
thrown. The spread daemon warns about an "Invalid Hint" message field,
probably suggesting that the message protocol seems broken.

I've already scanned the mail archives for similar problems, but could
not find an appropriate answer. It would be great if anyone could point
us in the right direction to solve this problem.

BTW: We use spread-4.0.0 on an Ubuntu 7.10 linux distribution configured
for testing purposes with a segment containing only the local host. We
applied the source changes in /include/sp.h /daemon/spread_params.h and

Best regards,


Dipl.-Inform. Sebastian Wrede                  phone +49-521-106-5148
Research Institute on Cognition and Robotics,
Bielefeld University, Germany            

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