21569 - Use 'Etag:' header contents for validation

Status: VERIFIED FIXED

(Core :: Networking: Cache, defect, P3)

Description

[Scott Furman]

HTTP 1.0 provides only the last-modified date to validate that a document has
not changed since last fetched (via use of an If-Modified-Since header added to
the request).  Last-Modified dates, however, only have resolution to one
second, which prevents correct caching of documents that can change more
than once per second.  HTTP 1.1 adds "entity tags" to support correct validation
of such documents and to support caching of documents for which
last-modified-date is not an appropriate validation mechanism.  HTTP 1.1
compliance mandates that clients make use of entity tags for validation if they
are present (via addition of an If-Match header to the request).

See this link for info on the use of entity tags in HTTP validation:

http://www.w3.org/Protocols/rfc2616/rfc2616-sec13.html#sec13.3.4

Comment 1

[Scott Furman]

Attachment: Implementation of entity-tag validation

Comment 2

[Scott Furman]

The fix for this bug is pretty trivial.  I've added a patch attachment
containing the fix.

Comment 3

[leger]

Bulk move of all Cache (to be deleted component) bugs to new Networking: Cache
component.

Comment 4

[Scott Furman]

The header is actually If-None-Match, not If-Match, so don't blindly apply the
first patch given.

Comment 5

[Scott Furman]

Fix checked into nsHTTPChannel.cpp rev 1.115

Comment 6

[Tom Everingham]

verified