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Deadwood update

 

September 12 2011

I have finished up all of the work I am going to do for MaraDNS and Deadwood for September 2011 (barring receiving more sponsorship). The work I have done this weekend was made possible by a fairly modest financial contribution.

Investigating the bug that Domenico Rotondi reported, I discovered that there have been some issues with RD (recursion desired) being incorrectly set when both upstream_servers and root_servers are set. I have updated the code and hopefully RD will now always have the correct value in DNS queries sent upstream.

In addition, I have updated Deadwood's parser:

  • I consider it a bug if any valid dwood3rc file does not parse in Python 2. That in mind, I have updated the dwood3rc parser to not allow parameters to have any leading whitespace (since whitespace is significant in Python).

    This is OK:

    recursive_acl = "127.0.0.1/16, 192.168.1.1/24"
    
    But this will raise an error:
     recursive_acl = "127.0.0.1/16, 192.168.1.1/24"
    
    (Observe the extra space in the left of the second example)

  • It is no longer allowed to set both root_servers or upstream_servers for a given name. In other words, a configuration like this will now raise an error:
    upstream_servers = {}
    upstream_servers["example.com."] = "127.0.0.1"
    root_servers = {}
    root_servers["example.com."] = "192.168.1.1"
    

  • Deadwood now raises a warning when the same name is set more than once. This will now trigger a warning:
    upstream_servers = {}
    upstream_servers["example.net."] = "10.1.2.3"
    upstream_servers["example.net."] = "192.168.1.1"
    
    I was tempted to make this fatal, but decided not to because making this fatal would make it more difficult to manage large anti-phish/malware blacklists.

  • It is no longer permitted to initialize root_servers or upstream_servers more than once. This will now raise an error:
    upstream_servers = {}
    upstream_servers["example.net."] = "10.1.2.3"
    upstream_servers = {}
    upstream_servers["example.com."] = "192.168.1.1"
    

  • Deadwood will now raise an error for invalid lists of root or upstream servers. This is now fatal:
    root_servers = {}
    root_servers["."] = "foo"
    
Yes, I am making the parser more anal. This is to help protect the user from typos and other errors causing problems with Deadwood, giving them a detailed description of the exact cause of a potential problem before Deadwood starts to resolve queries, so that they find and fix it before coming to the mailing list and complaining about the issue.

In addition, I want to ensure that any valid dwood3rc file is also a valid Python 2 script to make it much easier to use Deadwood configuration files in Python scripts.

I have also updated the SQA tests; they now run in both Scientific Linux 6 and in CentOS 5. Two new tests have been added: sqa_server_fail and sqa_root_upstream

Whew! This was a lot of work; I spent most of Saturday and a couple of hours this morning making all of these improvements. This will be all of the work I do with MaraDNS/Deadwood this month unless I can get more sponsorship.

It can be downloaded here:

http://www.maradns.org/deadwood/snap/
The next day I plan to work on MaraDNS/Deadwood without being compensated for my time is on October 5, 2011.

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