xing at litespeedtech.com xing at litespeedtech.com
Mon Sep 25 20:11:20 CEST 2006

Did a google search right after the email and realized my mistake. They 
are equivalent.

RFC 2616, section 4.2:

    Multiple message-header fields with the same field-name MAY be
    present in a message if and only if the entire field-value for that
    header field is defined as a comma-separated list [i.e., #(values)].
    It MUST be possible to combine the multiple header fields into one
    "field-name: field-value" pair, without changing the semantics of the
    message, by appending each subsequent field-value to the first, each
    separated by a comma. The order in which header fields with the same
    field-name are received is therefore significant to the interpretation
    of the combined field value, and thus a proxy MUST NOT change the
    order of these field values when a message is forwarded.


Poul-Henning Kamp wrote:
> In message <451819FA.1060802 at litespeedtech.com>, "xing at litespeedtech.com" write
> s:
>> Source: http://varnish.projects.linpro.no/changeset/1121
>> It appears it's missing a condition where varnish need to rewrite/append 
>> to the x-forwarded-for header if it already exists in the incoming http 
>> request instead of outputting a new/duplicate header.
> According to RFC2616 multiple headers append, they don't replace
> each other.
> So:
> 	X-Forewarded-for:,
> and
> 	X-Forewarded-for:
> 	X-Forewarded-for:
> should have the same semantic meaning.

More information about the varnish-dev mailing list