Cloudflare rate-limits by volume, and the block it handed out while this was
being built lasted over twenty minutes — too fragile to be the only thing behind
a button. So the download phase tries its sources in order: the anycast endpoint
first, then a plain 100 MB file on Linode's Seattle mirror, which has no opinion
about how much has been pulled today.
Only a refusal moves to the next one; anything else would fail the same way
twice. Every result names the source it used, and the page says "from
linode-seattle" rather than "via SEA" when it was the fallback — that mirror is
in one fixed place, so somewhere else it reads low, and a figure that quietly
came from a different continent would be a lie.
Upload stays on Cloudflare, which has never been the one to refuse.
Also: the too-short-window guard was refusing to divide 512 MiB by ten
milliseconds on a link fast enough to hit the runaway budget before the first
tick. It now guards against dividing by zero and nothing more.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Per machine like every other tab: the interfaces as the kernel has them
(addresses, MAC, MTU, negotiated link speed, carrier, totals, live rates from
the sampler's own sensors), the default route and resolvers, what the internet
sees of this connection, and a speed test with the last fifty results kept.
The test runs in the daemon, not the browser, so the figure is the line of the
machine in the switcher — the router's, if you switch to gate — and it carries
on when the phone locks. It measures against Cloudflare's public speed
endpoints, so there is nothing to install on any host, which is what makes it
work the same on Debian and on OpenWrt where flash is scarce.
What the measurement does and does not count:
- Several streams, HTTP/2 deliberately off. One stream over one connection
measures a congestion window, and HTTP/2 would put every stream back onto
one connection and measure the same thing.
- The first second of each phase is thrown away as the ramp.
- A phase ends on 64 MiB as well as on four seconds, so a fast line says what
it is without moving a gigabyte. A minimum window keeps a very fast line
from filling the cap before there is anything to divide by.
- Latency is the round trip less the far end's own Server-Timing. A zero-byte
response is mostly Cloudflare's worker thinking: left in, it reported 31 ms
for a line the edge itself measures at 3.5. Jitter is the mean change
between consecutive probes, so one slow probe cannot run away with it.
- The far end rate-limits by volume. So: a 20 s cooldown counted from the last
attempt rather than the last success, streams that retry twice, the rate
computed over the window in which bytes were actually still arriving, and a
plain sentence when it was refused. Coasting to the end of the clock with
nothing arriving reported a third of the truth.
The last result is published as net.internet.* sensors, each stamped with when
the test ran, so the line can be a widget, a graph, an alert or a Prometheus
series like anything else. The public address is refreshed on its own quarter
hour, which is worth having here: it is a DHCP lease and it moves.
Tests are offline — the window, the byte cap, the refusal and the cancellation
run against a local server; the route parser's byte order is pinned by a case
that would have caught the bug it did. The live measurement is behind
HAMLAB_NET_TEST=1.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
