MSP Loopback Test (ANetBBS ↔ ANetBBS)

This procedure verifies that two ANetBBS instances can exchange Inter-BBS
Instant Messages over MSP (RFC 1312) and that SYSTAT/ActiveUser query
also works between them. Use it after upgrading the MSP module to confirm
nothing regressed.

What it tests

1. MSP message wire delivery (TCP/18-equivalent)
2. Inbound persistence in the recipient's InstantMessage table
3. SYSTAT/ActiveUser UDP query + Finger-style reply parsing
4. The web /imsg/send route's user@host paste-friendly parsing

Run it

cd /mnt/hdd2/AIANETBBS/anetbbs-rebuilt
python3 /tmp/msp_loopback_test.py

The test:
- Creates two isolated SQLite DBs in /tmp/anetbbs-loopback-a and -b
- Runs instance B's MSP listener on port 12118 and SYSTAT on 12111
(chosen above the privileged-port boundary so no setcap is needed)
- Acts as instance A in-process — sends one direct MSP via send_msp(),
one via the /imsg/send HTTP route with admin@127.0.0.1 pasted into
the recipient field

Expected output

=== ANetBBS MSP loopback test ===

[Setup] Building instance B (listener) ...
  instance B: MSP 12118, SYSTAT 12111, dir /tmp/anetbbs-loopback-b

[1] Sending MSP from A to B (admin@127.0.0.1)
  ✓  send_msp returned True

[2] Verify B persisted the message
  ✓  InstantMessage row exists with correct body

[3] SYSTAT query 127.0.0.1:12111 (B)
  ✓  reply contains BBS name
  ✓  reply mentions "active"

[4] /imsg/send accepts "admin@127.0.0.1" pasted into recipient
  ✓  /imsg/send returned redirect (success)
  ✓  B received the second message

All six checks must pass.

What to check on a real two-host setup

If you have two ANetBBS hosts on the network:

1. On both hosts, ensure the MSP listener is bound (not "permission
   denied" in the bbs.log). See INSTALL.md for the three options to bind
   to the privileged ports 11/UDP and 18/TCP.

2. Confirm with nc from either host:
   bash nc -zv other.bbs.example 18 # TCP MSP
   "Connection succeeded" = port is reachable.

3. From host A, log in as a user, open Messaging → Inter-BBS IM (MSP),
   click Send IM, paste username@other.bbs.example, type a message,
   submit. Flash should say "Instant message sent to ...".

4. On host B, the recipient logs in and opens the same menu — the message
   appears in their IM inbox with sender label username@A_BBS_NAME.

Troubleshooting

• "Connection refused" on port 18 → listener never bound. Check the bbs.log
  for MSP: cannot bind ... Permission denied. Apply one of the three
  privilege fixes in INSTALL.md.
• Sent OK but never received → check the recipient name on the remote BBS.
  The MSP server falls back from username to display_name but that's
  it — there's no fuzzy match.
• SYSTAT reply garbled → the responder is probably emitting CP437 box
  glyphs that need rendering. The query_systat() client decodes UTF-8
  first then falls back to latin-1, so high bytes survive but won't show
  pretty in a plain text view.