[squid-users] Connection occasionally not ending after adapting response with ICAP

[Moti Berger]

I'm sorry for the bad format and for the uncompressed file.
Indeed adding a Content-Length:0 solved the issue.
This is BTW the preferred way for me since the URL I'm redirecting to
explains
why the redirection occurred.

Thanks a lot for your help.

On Wed, Dec 30, 2020 at 6:48 PM Alex Rousskov <
rousskov at measurement-factory.com> wrote:

> On 12/30/20 10:40 AM, Moti Berger wrote:
>
> >>>> I don't see the "0 CR LF CR LF" at all, not only for those URLs that
> > cause the curl to hang.
>
> I suspect that none of those ICAP responses have HTTP bodies. An ICAP
> response without an HTTP body, in itself, is not a bug, but it probably
> explains the problem you are having. See below for more details.
>
>
> > I'm attaching a tcpdump file.
>
> FWIW, my wireshark cannot read your packet capture file: "The capture
> file appears to be damaged or corrupt. File has 1852785440-byte packet,
> bigger than maximum of 262144". In the future, you should compress such
> files before sharing them via email.
>
> However, looking at the ASCII parts of that capture file, I probably see
> the likely culprit. The ICAP response below can be considered invalid
> or, at least, rather difficult to handle correctly:
>
> > ICAP/1.0 200 OK
> > ISTag: "tmrCy72n1Qgsn1mxBipIb4jdEYdce3"
> > Date: Wed, 30 Dec 2020 15:07:52 GMT
> > Server: BaseICAP/1.0 Python/3.6.12
> > Encapsulated: res-hdr=0, null-body=140
> >
> > HTTP/1.1 307 Temporary Redirect
> > location: http://www.redirect.url
> > Cache-Control: no-cache, no-store, must-revalidate
> > Pragma: no-cache
>
>
> The HTTP 307 response header sent by the ICAP server promises an HTTP
> response body (per HTTP rules), but the ICAP response has no HTTP body
> (per the "null-body" value in the Encapsulated header).
>
> I do not remember what Squid does in this problematic case, but I
> suspect the outcome is a stuck HTTP transaction.
>
> You should fix the ICAP service to either stop promising an HTTP
> response body or provide one. The easiest (but ugly) fix may be to add
> Content-Length:0 to the HTTP header returned by the ICAP service. A
> better fix would be to include a real body that explains why the request
> was redirected or provides some reference to the corresponding decision,
> for triage.
>
>
> HTH,
>
> Alex.
>
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