FA-7591 / WebSocket and browser transport policies / Open access

Websocket client frames require masking and server frames forbid it · case 01

Websocket client frames require masking and server frames forbid it.

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

ROOT CAUSE

The faulty implementation uses `masked` for the websocket-client-frames-require-masking-and-server-frames-forbid-it decision.

VERIFIED REPAIR

Apply the explicit websocket-client-frames-require-masking-and-server-frames-forbid-it contract, including the tested boundary and negative cases.

Unsuccessful approach: The attempted repair uses `not masked` and still violates a separate fixture.

Case contract

Bounded offline decision model: websocket client frames require masking and server frames forbid it. 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 websocket-client-frames-require-masking-and-server-frames-forbid-it 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(client, masked):
    return masked
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(True, True), True)", "check('fixture 2', solve(True, False), False)", "check('fixture 3', solve(False, True), False)", "check('fixture 4', solve(False, False), True)"]
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`	`False`	Failed
fixture 4	`False`	`True`	Failed
fixture 1	`True`	`True`	Passed

SHA-256 / 8e0dec3212134b6a86fa5445c86bb310401319307a7635dd64d6a33c916d836e

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(client, masked):
    return not masked
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(True, True), True)", "check('fixture 2', solve(True, False), False)", "check('fixture 3', solve(False, True), False)", "check('fixture 4', solve(False, False), True)"]
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`	`False`	Passed
fixture 4	`True`	`True`	Passed
fixture 1	`False`	`True`	Failed

SHA-256 / 273319bd43bf3e7b396d034d967ee541794e4c5e35339d02dddf17cfece3eabe

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(client, masked):
    return client == masked
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(True, True), True)", "check('fixture 2', solve(True, False), False)", "check('fixture 3', solve(False, True), False)", "check('fixture 4', solve(False, False), True)"]
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	`False`	`False`	Passed
fixture 4	`True`	`True`	Passed
fixture 1	`True`	`True`	Passed

SHA-256 / 65a5dcab40fed485b4931552c8631dc44676cf64110ccba8dd825e545c340c70

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 2026-09-29T14:38:13.551019+00:00.

Case digest / fe6455df4dce805ccdfe90ec46b8a67c7289a8c478f69b0a4955a270a1f4a714