[Kamailio-Devel] [SR-Dev] content length

[Andrei Pelinescu-Onciul]

On Mar 31, 2009 at 10:57, Klaus Darilion <klaus.mailinglists at pernau.at> wrote:
> 
> 
> Andrei Pelinescu-Onciul schrieb:
> >On Mar 30, 2009 at 16:06, Daniel-Constantin Mierla <miconda at gmail.com> 
> >wrote:
> >>Hello,
> >>
> >>the data lumps system is critically affected if content-length is wrong 
> >>for UDP. The anchor_lump() calls abort() in the case content-length is 
> >>higher than actually body length.
> >
> >It's true that anchor_lump() calls abort if the offset passed to it is
> >outside the message, but I don't see where anchor_lump() is called with
> >a value depending on Content-Length (at least in sip-router and ser).
> >
> >>This can be prevented by called sanity 
> >>module to check the content length, however, I consider being too 
> >>drastic to have abort in such case, it would be better to return an 
> >>error and let the sip router process other messages. Opinions?
> >>
> >>Checking sip-router sources, it faces same issue.
> >>
> >>Another option would be to correct the C-L value locally, but the right 
> >>one is that phone vendor fixes its side.
> >
> >It's fixed automatically in sip-router, if the destination protocol is
> >tcp or tls.
> 
> How can this be fixed automatically? How will the proxy know when then 
> body ends and the next message starts?

If the destination is tcp or tls, but the source is not (source is udp
or sctp).
One more clarification: it does not the fix the value of the content
length visible from sr, it will fix the Content-Length header in the
forwarded message.

> 
> regards
> klaus
> 
> PS: IMO the server should respond with "400 wrong content length" if 
> accessing of the body is required and the length is wrong

Why would anyone use content-length for accessing the body in the first
place? You always know (in sr/ser/k) where the message ends
(msg->buf+msg->len) and where the body starts (get_body(msg)).


Andrei