FA-7676 / WebSocket and browser transport policies / Open access

Cors preflight header names are case insensitive · case 01

Cors preflight header names are case insensitive.

Verified by executionVariant 1 · 4 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The faulty implementation uses `set(requested) <= set(allowed)` for the cors-preflight-header-names-are-case-insensitive decision.

VERIFIED REPAIR

Apply the explicit cors-preflight-header-names-are-case-insensitive contract, including the tested boundary and negative cases.

Unsuccessful approach: The attempted repair uses `bool(set(requested)&set(allowed))` and still violates a separate fixture.

Case contract

Bounded offline decision model: cors preflight header names are case insensitive. Inputs are already validated protocol fields; the explicit fixtures define the supported policy, not a complete protocol implementation.

Why this case matters

This deterministic websocket and browser transport policies model isolates the cors-preflight-header-names-are-case-insensitive policy at a network component boundary.

1 / The failure

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import ipaddress
import re
from urllib.parse import urlsplit, urljoin
N = 1
observations = []
def solve(requested, allowed):
    return set(requested) <= set(allowed)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(['X-Test'], ['x-test']), True)", "check('fixture 2', solve(['x', 'y'], ['x']), False)", "check('fixture 3', solve([], []), True)", "check('fixture 4', solve(['x'], []), False)"]
for _line in _fixtures[N % len(_fixtures):] + _fixtures[:N % len(_fixtures)]:
    exec(_line)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
fixture 2	`False`	`False`	Passed
fixture 3	`True`	`True`	Passed
fixture 4	`False`	`False`	Passed
fixture 1	`False`	`True`	Failed

SHA-256 / 5435fc6db663057dae9ab2d9611464da1d2630662749d6c323b3530b0efff3a6

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import ipaddress
import re
from urllib.parse import urlsplit, urljoin
N = 1
observations = []
def solve(requested, allowed):
    return bool(set(requested)&set(allowed))
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(['X-Test'], ['x-test']), True)", "check('fixture 2', solve(['x', 'y'], ['x']), False)", "check('fixture 3', solve([], []), True)", "check('fixture 4', solve(['x'], []), False)"]
for _line in _fixtures[N % len(_fixtures):] + _fixtures[:N % len(_fixtures)]:
    exec(_line)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
fixture 2	`True`	`False`	Failed
fixture 3	`False`	`True`	Failed
fixture 4	`False`	`False`	Passed
fixture 1	`False`	`True`	Failed

SHA-256 / c3bbf76907bf81d1c9a741e1d696786fcc2ddd4f9589324bbc8d5f960ab2652b

3 / The verified repair

Exit 0

"""Failure Map reference implementation. Python standard library only."""
import json
import ipaddress
import re
from urllib.parse import urlsplit, urljoin
N = 1
observations = []
def solve(requested, allowed):
    return {x.lower() for x in requested} <= {x.lower() for x in allowed}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(['X-Test'], ['x-test']), True)", "check('fixture 2', solve(['x', 'y'], ['x']), False)", "check('fixture 3', solve([], []), True)", "check('fixture 4', solve(['x'], []), False)"]
for _line in _fixtures[N % len(_fixtures):] + _fixtures[:N % len(_fixtures)]:
    exec(_line)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
fixture 2	`False`	`False`	Passed
fixture 3	`True`	`True`	Passed
fixture 4	`False`	`False`	Passed
fixture 1	`True`	`True`	Passed

SHA-256 / 6d0d7f2ed5241aba49e8bbdf0afca084ca37fc384150f96da7889336e2879889

Verification & scope

Bounded deterministic policy model over validated inputs; not a complete protocol stack or an interoperability claim. The five variants rotate the same explicit fixture set. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.

Observations recorded using Python 3.12.14 at 2026-09-29T14:38:14.198337+00:00.

Case digest / 95bd17ce54a1a1b796002848eb579563302a9d643a0952ffb57fc3b3d48691cd