Podcast Episode Details

119: There be Dragons, BSD Dragons anyway

This week on BSDNow - It’s getting close to christmas and the

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Headlines

n2k15 hackathon reports

• tedu@ worked on rebound, malloc hardening, removing legacy code
• “I don't usually get too involved with the network stack, but sometimes you find yourself at a network hackathon and have to go with the flow. With many developers working in the same area, it can be hard to find an appropriate project, but fortunately there are a few dusty corners in networking land that can be swept up without too much disturbance to others.”
• “IPv6 is the future of networking. IPv6 has also been the future of networking for 20 years. As a result, a number of features have been proposed, implemented, then obsoleted, but the corresponding code never quite gets deleted. The IPsec stack has followed a somewhat similar trajectory”
• “I read through various networking headers in search of features that would normally be exposed to userland, but were instead guarded by ifdef _KERNEL. This identified a number of options for setsockopt() that had been officially retired from the API, but the kernel code retained to provide ABI compatibility during a transition period. That transition occurred more than a decade ago. Binary programs from that era no longer run for many other reasons, and so we can delete support. It's only a small improvement, but it gradually reduces the amount of code that needs to be reviewed when making larger more important changes”
• Ifconfig txpower got similar treatment, as no modern WiFi driver supports it
• Support for Ethernet Trailers, RFC 893, enabled zero copy networking on a VAX with 512 byte hardware pages, the feature was removed even before OpenBSD was founded, but the ifconfig option was still in place
• Alexandr Nedvedicky (sashan@) worked on MP-Safe PF
• “I'd like to thank Reyk for hackroom and showing us a Christmas market. It was also my pleasure to meet Mr. Henning in person. Speaking of Henning, let's switch to PF hacking.”
• “mpi@ came with patch (sent to priv. list only currently), which adds a new lock for PF. It's called PF big lock. The big PF lock essentially establishes a safe playground for PF hackers. The lock currently covers all pf_test() function. The pf_test() function parts will be gradually unlocked as the work will progress.
• To make PF big lock safe few more details must be sorted out. The first of them is to avoid recursive calls to pf_test(). The pf_test() could get entered recursively, when packet hits block rule with return-* action. This is no longer the case as ip*_send() functions got introduced (committed change has been discussed privately). Packets sent on behalf of kernel are dispatched using softnet task queue now. We still have to sort out pf_route*() functions. The other thing we need to sort out with respect to PF big lock is reference counting for

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  Published on 10 years ago