This commit makes the DNS resolution code better suited for both
filtering on cname and ip address. The change allows early availability
of ip address so that `ipaddress=` option can be matched at
onBeforeRequest time.
As a result, it is now possible to block root document using
`ipaddress=` option -- so long as an ip address can be extracted
before first onBeforeRequest() call.
Related issue:
https://github.com/uBlockOrigin/uBlock-issues/issues/2792
Caveat
------
the ip address used is the first one among the list of ip
addresses returned by dns.resolve() method. There is no way for uBO
to know which exact ip address will be used by the browser when
sending the request, so this is at most a best guess. The exact IP
address used by the browser is available at onHeadersReceived time,
and uBO will also filter according to this value, but by then the
network request has already been sent to the remote server.
Possibly a future improvement would make available the whole list
of ip addresses to the filtering engine, but even then it's impossible
to know with certainty which ip address will ultimately be used by the
browser -- it is entirely possible that the ip address used by the
browser might not be in the list received through dns.resolve().
If an IP address can be extracted from the hostname portion of
a URL, the IP address matching will be performed at onBeforeRequest()
time.
Regardless, IP address matching will subsequently always be performed
at onHeadersReceived() time as the request details at that point
contain a reliable IP address value on supported platforms (Firefox-
only as of now).
The `cap_ipaddress` now evaluates to `true` in Chromium-based
browsers. Even though these browsers are unable to provide reliable
IP address value at onHeadersReceived() time, they can still
perform IP address matching for IP address extracted from hostname
portion of a URL.
A new icon has been added to the popup panel, to open a popup
window with a terse list of DNR events for the current tab, in
reverse chronological order (most recent DNR event appears at
the top).
The new ability is available only when the extension is sideloaded,
as per `declarativeNetRequestFeedback` documentation. Ref:
https://developer.chrome.com/docs/extensions/reference/api/declarativeNetRequest#event-onRuleMatchedDebug
Purposefully minimal, so as to have something rather than nothing
when having to diagnose filtering issue with the DNR API. Example:
https://github.com/uBlockOrigin/uBOL-home/issues/156
The content of the popup window does not dynamically update, force
a refresh (F5) to get the most recent DNR events. This might be
improved in the future.
The DNR event buffer is not persisted, so the buffer is empty when
service worker is restarted. This might be improved in the future
by using session storage API.
There is no output filtering ability in this first draft. This
might be improved in the future.
DNR rules are reported. The filter from which a DNR rule
originates is not reported. Given that the rulesets are optimized
after conversion from original filter lists to reduce the DNR rule
count, this is unlikely to ever be possible.
Raymond Hill