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Re: [reSIProcate] Content-Length is not taken seriously by SipMessage


There is no problem with the TCP implementation right now IIRC.
This is only UDP, and only an issue for UDP that we _receive_ (we will never generate a UDP packet with
an incorrect content length).

There are totally hosed, but reasonably widely deployed implementations that don't know how to count and create UDP where the content-length is off by 2 (or worse). Ignoring the content-length for UDP has improved the ability of some products built with resiprocate to work in environments with that badness without suffering (at least initially) from the risks of not honoring that Content-Length header field.

My proposal is that we make this a configuration option in the stack. And for clarity I'll repeat that this affects ONLY what we do with UDP packets we receive. The default needs to be what the spec says to do. Those applications that want to take the risk of ultimately being poisonable for the Postel-maxim based trade of working with more broken things now should be allowed to do so by making a single configuration
call at startup.

Thoughts?

RjS

On Aug 4, 2006, at 12:15 PM, Byron Campen wrote:


Derek MacDonald wrote:
It isn't ignored for TCP; it is ignored for UDP. The rational for this is people are more likely to get their content length wrong as opposed to stray
bytes in a UDP packet.


And that works just fine until some bozo notices that the specification requires, at a MUST level, implementations to ignore extra cruft in UDP packets, and decides it's a safe place to piggyback some proprietary information or diagnostics. Yes: bad them, but it takes two to dance this particular tango, and you've just volunteered.

/a

Also, we should not encourage bad behavior by letting this slide, because this sort of mistake kills TCP interop.

Best regards,
Byron Campen

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