On 20/07/2013 11:21 a.m., Dave Burkholder wrote:
Hi everyone,
I'm running an ICAP client that can't read sdch content encodings so I
want to strip those headers out. (I realize this is mostly an edge
case anyway, but never mind that for now).
I have these rules to strip out the Accept-Encoding header if it
contains sdch.
acl sdch req_header Accept-Encoding [-i] sdch
request_header_access Accept-Encoding deny sdch
What is the relationship between request_header_access and
request_header_replace?
As documented in the config manual
http://www.squid-cache.org/Doc/config/request_header_access/
"
The option is applied to individual outgoing request header
fields. For each request header field F, Squid uses the first
qualifying sets of request_header_access rules:
1. Rules with header_name equal to F's name.
2. Rules with header_name 'Other', provided F's name is not
on the hard-coded list of commonly used HTTP header names.
3. Rules with header_name 'All'.
Within that qualifying rule set, rule ACLs are checked as usual.
If ACLs of an "allow" rule match, the header field is allowed to
go through as is. If ACLs of a "deny" rule match, the header is
removed and request_header_replace is then checked to identify
if the removed header has a replacement. If no rules within the
set have matching ACLs, the header field is left as is.
"
If I want to strip sdch and allow gzip, would the following ruleset
accomplish this?
acl sdch req_header Accept-Encoding [-i] sdch
request_header_access Accept-Encoding deny sdch
request_header_replace Accept-Encoding Accept-Encoding: gzip
It will strip out any Accept-Encoding line containing sdch and replace
it with a line accepting *only* gzip content. Regardless of whether the
client accepts gzip as well as sdch.
Does the request_header_replace only fire if request_header_access
actually matched?
See above.
Amos
