Wireshark-dev: Re: [Wireshark-dev] PCAP-NG Block Formats
Date Index · Thread Index · Other Months · All Mailing Lists
Date Prev · Date Next · Thread Prev · Thread Next
From: Guy Harris <guy@xxxxxxxxxxxx>
Date: Fri, 10 Jun 2016 11:35:27 -0700
On Jun 10, 2016, at 11:16 AM, Guy Harris <guy@xxxxxxxxxxxx> wrote:

> Perhaps a future version of the spec should allow it to be omitted, and specify that either 1) not having enough space left in the block for a full option (i.e., fewer than 4 bytes left in the packet) or 2) seeing an endofopt terminates the processing of options (in case a writer puts out an endofopt and some amount of extra junk after it).

No, Postel's right:

	https://en.wikiquote.org/wiki/Jon_Postel 

be conservative in what you do, be liberal in what you accept from others.

I'll update the spec to say that writers MUST put an endofopt into the list (so that buggy readers that don't check for end-of-block will stop parsing options) and readers MUST NOT assume the list has an endofopt (so buggy writers that don't add endofopt won't cause them to run past the end of the block) and SHOULD NOT reject blocks where the option list doesn't have an endofopt (so files written by buggy writers are still readable).