[squid-users] "helperHandleRead: unexpected read" for helper function

[Justin Michael Schwartzbeck]

Hello all... I would really appreciate some help.

So I have written an external acl helper in C++ that talks to a REST API
that I developed. Here is a github link (don't worry, it is pretty short,
and the only parts you need to look at are lines 46, 52, 58 and 60):

https://github.com/e2guardian-angel/squid-acl-category-helper/blob/main/category_host.cpp

I have it all configured in my squid.conf:
external_acl_type host_category_helper %ACL %DST
/usr/local/bin/squidhelpers/host_category_helper
acl searchengines external host_category_helper
...
ssl_bump bump searchengines
ssl_bump none all

and as far as I can tell, it is working: search engines are being matched
(for the most part) and decrypted, as expected, and nothing else is being
decrypted.

However, I am seeing a million of the following lines:
2021/05/08 02:04:57| helperHandleRead: unexpected read from
host_category_helper #Hlpr6, 4 bytes 'ERR

I notice it only seems to be happening for the ERR (no match), I don't see
it for the OK (match).

I googled this issue and see a lot of threads here about making sure there
is only one line of output per line of input. I am definitely seeing this
when I just run the helper manually:
$ docker exec -it squid /usr/local/bin/squidhelpers/host_category_helper

searchengines google.com
OK
searchengines facebook.com
ERR
searchengines imdb.com
ERR


So it seems that it should be working as expected. I don't see any other
newlines. I saw also some snippet about concurrency being an issue, this
could be the case, since I did see this one-off in the squid output:
2021/05/08 02:04:59| helperHandleRead: unexpected read from
host_category_helper #Hlpr6, 8 bytes 'ERR
ERR
'

But this doesn't make sense to me since only one helper appears to be
running:
2021/05/08 01:52:04| helperOpenServers: Starting 1/5 'host_category_helper'
processes


Is there anything glaring here that could be the issue? Is it indeed a
concurrency problem? I would have assumed that each helper (there are 5 of
them) would have their own stdin/stdout and be writing to/from it rather
than everyone at once. It also seems a little suspicious that I am only
seeing this for ERR, not OK... you are supposed to print ERR when there is
not a match, correct?

Any help would be greatly appreciated... I am getting so close to having
this fully functional.

-Justin
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