can_write_to_data_dir() touched and then deleted data/test.txt, which
silently wiped any file of the user's that happened to have that name.
It now uses tempfile.NamedTemporaryFile in the data dir, which picks an
unused name and removes only the file it created.
Tasks 1-3 of the backend security audit all need to answer "is this browser
origin someone we trust". Build it once, driven entirely by the existing
SPOOLMAN_CORS_ORIGIN rather than a new env var.
- Unset means same-origin only, which is right for nearly every deployment.
Non-browser clients (Moonraker, OctoPrint) send no Origin and are unaffected.
- A list means those origins plus our own.
- "*" and debug mode mean "I do not want origin checks" and are honoured as
such, with a loud startup warning. An operator who writes "*" is opting out;
reinterpreting it as something narrower would leave them no way to say so.
Also accept X-Forwarded-Host, so a reverse proxy that rewrites Host (nginx
without proxy_set_header Host $host, Apache without ProxyPreserveHost On) does
not see the guard reject its own web UI. A malicious page cannot set that
header on any of the vectors the guard exists to stop: forms cannot set request
headers, nor can the browser WebSocket API, and a fetch that adds one needs a
CORS preflight it will not get.
get_cors_origin() now normalizes its entries -- it was a bare split(","), so
"https://a, https://b" yielded " https://b", which no Origin header can match.
CORS itself benefits from the same fix. The raw value is kept in the startup
log so a typo stays visible.
Adds tests/ for backend unit tests, runnable with `poe test` and wired into the
lefthook ci group. Nothing enforces this helper yet; that is tasks 1-3.
Donkie