Given the broker's address and its certificate, mesh-control now issues a
token carrying everything ADR 0004 asks for: where to connect, what to expect
there, whose signature to believe afterwards, and a one-time right to join.
Verified by decoding one and checking the fingerprint against `openssl x509 |
sha256sum` -- they match.
The fingerprint is derived from the certificate on disk and never configured.
A configured pin can drift from the certificate it describes, and a drifted pin
is worse than none: every node issued a token during the drift refuses to
connect, and the failure looks like an attack rather than a mistake.
Computed over DER, which is what a client sees on the wire. Hashing the PEM
text instead would mean the same certificate, re-wrapped with different line
endings, produced a different pin -- there is a test for exactly that, and one
for pointing this at tls.key by mistake, which would otherwise produce a
confident pin over the wrong file.
Having no broker stays a state rather than a failure: a control plane holds
records and a signing key without one. Having half a broker is refused, because
a token with an address and nothing to check it against invites a node to trust
whatever answers.
Fault injection caught the same weak test I wrote earlier in the day -- asking
whether something failed rather than why, so deleting the guard changed nothing
because it failed one line later anyway. Both are now asserted on the reason.
jschoubben
ea6569277d