TCP_* codes; please review

In article <199610220412.RAA00565@gerbil.cs.waikato.ac.nz> you write:

>I'm getting several of these in my access.log:
>
> TCP_EXPIRED_MISS/304

[...]

>Please clear my confusion...

I'm also a bit confused by the wide variety of these codes so I decided to
make a list of these. Please review, send additions etc. and I'll try to
make a list suitable for inclusion in the Squid FAQ.

Arjan

-----------------------------------------------------------------------------

Overview of Squid result codes in access.log
============================================

A result code consists of a keyword, a slash and a 3-digit return code.
The return code is the return code returned to the client, not the return
code received from the original site.

TCP_HIT/TCP_MISS
----------------

TCP_HIT/200

An object was present in the cache and is returned to the client.

TCP_MISS/200

An object was not present in the cache (or not cacheable), was fetched and
was returned to the client.

TCP_MISS/304

???

TCP_IMS_HIT/TCP_IMS_MISS
------------------------

TCP_IMS_HIT/200

An object was requested with an If-Modified-Since header. It was present
in the cache with a Last-Modified: date later than the IMS date and a 200
response was returned to the client.

TCP_IMS_HIT/304

An object was requested with an If-Modified-Since header. It was present
in the cache with a Last-Modified: date earlier or equal to the IMS date
and a 304 response was returned to the client.

TCP_IMS_MISS/200

Does not occur?

TCP_IMS_MISS/304

An object was requested with an If-Modified-Since header. It was not
present in the cache but was fetched. A 304 response was returned to the
client because the last modified date of the object was less or equal to
the IMS date sent by the client.

TCP_EXPIRED_HIT/TCP_EXPIRED_MISS
--------------------------------

TCP_EXPIRED_HIT/200

An object was present in the cache but had expired. Squid issued an
If-Modified-Since request and got a 200 response. The object is returned
to the client with a 200 response.

TCP_EXPIRED_HIT/304 (1.1.beta9 and later) TCP_EXPIRED_MISS/304 (earlier)

An object was present in the cache but had expired. Squid issued an
If-Modified-Since request and got a 304 response. The object's expiry time
is recalculated and a 304 response is returned to the client.

TCP_EXPIRED_MISS/200

An object was present in the cache but had expired. Squid issued an
If-Modified-Since request and got a 200 response. The object is returned
to the client as a 200 response.

[what's the difference between TCP_EXPIRED_HIT/200 and
TCP_EXPIRED_MISS/200?]

TCP_REFRESH
-----------

TCP_REFRESH/200

A request was made with the (Shift-) Reload button and the 'Pragma:
no-cache' header was sent by the client but no If-Modified-Since header.
The object was fetched and was returned to the client with a 200 response.

TCP_REFRESH/304

A request was made with the Reload button and the 'Pragma: no-cache'
header was sent by the client together wit an If-Modified-Since header.
The object was fetched, was not younger than the IMS date and a 304
response was returned to the client.
Received on Tue Oct 22 1996 - 14:37:07 MDT