informix-db/docs/CAPTURES/03-py-connect-only.socat.log
Ryan Malloy ea00990774 Phase 1 polish: PDU match test catches a real capability-int bug
Polish item #1: byte-for-byte regression test that asserts our
generated login PDU is structurally identical to JDBC's reference
captured in docs/CAPTURES/01-connect-only.socat.log.

The test (tests/test_pdu_match.py) immediately caught a real bug:
the capability section was misread during Phase 0 byte-decoding.
Earlier text claimed Cap_1=1, Cap_2=0x3c000000, Cap_3=0 — actually:

  Cap_1 = 0x0000013c   (= (capability_class << 8) | protocol_version
                          where protocol_version = 0x3c = PF_PROT_SQLI_0600)
  Cap_2 = 0
  Cap_3 = 0

The misalignment was: the 0x3c byte I attributed to Cap_2's high
byte was actually Cap_1's low byte. The dev-image server is
permissive enough to accept arbitrary capability values, so the
connection succeeded even with the wrong bytes — but the PDU wasn't
structurally identical to JDBC's reference. SERVER-ACCEPTS ≠
STRUCTURALLY-CORRECT. This is exactly why the byte-for-byte diff
was the right polish item; "it connects" was a false ceiling.

After fix:
- 6 PDU-match tests assert byte-for-byte equality at offsets 2..280
  (the structural prefix: SLheader sans length, all login markers,
  capability ints, username, password, protocol IDs, env vars).
- Bytes 280+ legitimately differ per process (PID, TID, hostname,
  cwd, AppName) — those are NOT asserted.
- Length field (offsets 0..1) also legitimately differs because our
  PDU has shorter env list and AppName.
- Test uses monkey-patched IfxSocket so no network is needed.

Polish item #2: Makefile per global CLAUDE.md convention. Targets:
install, lint, format, test, test-integration, test-all, test-pdu,
ifx-up/down/logs/shell/status, capture (re-run JDBC scenarios under
socat), clean. `make` (no target) prints help.

Doc updates:
- PROTOCOL_NOTES.md §12: corrected capability section with the
  actual values and an explanation of the methodology lesson
- DECISION_LOG.md: new entry recording the correction with a
  pointer to the regression test and the takeaway

Side artifacts:
- docs/CAPTURES/03-py-connect-only.socat.log
- docs/CAPTURES/04-py-no-database.socat.log
- docs/CAPTURES/05-py-fixed-caps.socat.log

Test counts: 40 unit + 6 integration = 46 total, all green, ruff clean.
2026-05-02 20:18:03 -06:00

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2026/05/02 20:10:06 socat[3937281] N listening on AF=2 0.0.0.0:9090
2026/05/02 20:10:07 socat[3937281] N accepting connection from AF=2 127.0.0.1:59562 on AF=2 127.0.0.1:9090
2026/05/02 20:10:07 socat[3937281] N opening connection to 127.0.0.1:9088
2026/05/02 20:10:07 socat[3937281] N opening connection to AF=2 127.0.0.1:9088
2026/05/02 20:10:07 socat[3937281] N successfully connected from local address AF=2 127.0.0.1:39822
2026/05/02 20:10:07 socat[3937281] N successfully connected to 127.0.0.1:9088
2026/05/02 20:10:07 socat[3937281] N starting data transfer loop with FDs [6,6] and [5,5]
> 2026/05/02 20:10:07.218292 length=395 from=0 to=394
01 8b 01 3c 00 00 00 64 00 65 00 00 00 3d 00 06 49 45 45 45 4d 00 00 6c 73 71 6c 65 78 65 63 00 00 00 00 00 00 06 39 2e 32 38 30 00 00 0c 52 44 53 23 52 30 30 30 30 30 30 00 00 05 73 71 6c 69 00 00 00 00 01 3c 00 00 00 00 00 00 00 00 01 00 09 69 6e 66 6f 72 6d 69 78 00 00 07 69 6e 34 6d 69 78 00 6f 6c 00 00 00 00 00 00 00 00 00 3d 74 6c 69 74 63 70 00 00 00 00 00 01 00 68 00 0b 00 00 00 03 00 09 69 6e 66 6f 72 6d 69 78 00 00 0a 73 79 73 6d 61 73 74 65 72 00 00 00 00 00 00 00 00 00 00 6a 00 06 00 07 44 42 50 41 54 48 00 00 02 2e 00 00 0e 43 4c 49 45 4e 54 5f 4c 4f 43 41 4c 45 00 00 0d 65 6e 5f 55 53 2e 38 38 35 39 2d 31 00 00 11 43 4c 4e 54 5f 50 41 4d 5f 43 41 50 41 42 4c 45 00 00 02 31 00 00 07 44 42 44 41 54 45 00 00 06 59 34 4d 44 2d 00 00 0c 49 46 58 5f 55 50 44 44 45 53 43 00 00 02 31 00 00 09 4e 4f 44 45 46 44 41 43 00 00 03 6e 6f 00 00 6b 00 00 00 00 00 3c 14 0d 00 00 00 00 00 0b 72 70 6d 2d 62 75 6c 6c 65 74 00 00 00 00 29 2f 68 6f 6d 65 2f 72 70 6d 2f 63 6c 61 75 64 65 2f 69 6e 66 6f 72 6d 69 78 2f 70 79 74 68 6f 6e 2d 6c 69 62 72 61 72 79 00 00 74 00 21 00 00 00 00 00 00 00 00 00 17 69 6e 66 6f 72 6d 69 78 2d 64 62 40 70 69 64 33 39 33 37 32 39 33 00 00 7f
< 2026/05/02 20:10:07.221921 length=276 from=0 to=275
01 14 02 3c 10 00 00 64 00 65 00 00 00 3d 00 06 49 45 45 45 49 00 00 6c 73 72 76 69 6e 66 78 00 00 00 00 00 00 2f 49 42 4d 20 49 6e 66 6f 72 6d 69 78 20 44 79 6e 61 6d 69 63 20 53 65 72 76 65 72 20 56 65 72 73 69 6f 6e 20 31 35 2e 30 2e 31 2e 30 2e 33 00 00 07 73 65 72 69 61 6c 00 00 09 69 6e 66 6f 72 6d 69 78 00 00 00 01 3c 00 00 00 00 00 00 00 00 00 00 00 00 00 00 6f 6e 00 00 00 00 00 00 00 00 00 3d 73 6f 63 74 63 70 00 00 00 00 00 00 00 66 00 00 00 00 00 00 00 00 00 00 00 1d 00 00 00 6b 00 00 00 00 00 00 03 1a 00 00 00 00 00 0d 32 33 32 37 63 34 33 35 34 65 61 38 00 00 00 00 0f 2f 68 6f 6d 65 2f 69 6e 66 6f 72 6d 69 78 00 00 6e 00 04 00 00 00 00 00 74 00 33 00 00 00 c8 00 00 00 c8 00 29 2f 6f 70 74 2f 69 62 6d 2f 69 6e 66 6f 72 6d 69 78 2f 76 31 35 2e 30 2e 31 2e 30 2e 33 2f 62 69 6e 2f 6f 6e 69 6e 69 74 00 00 7f
> 2026/05/02 20:10:07.222169 length=2 from=395 to=396
00 38
2026/05/02 20:10:07 socat[3937281] N socket 2 (fd 5) is at EOF
2026/05/02 20:10:07 socat[3937281] N socket 1 (fd 6) is at EOF
2026/05/02 20:10:07 socat[3937281] N exiting with status 0