FA-7566 / Multiplexed protocols / Open access

Quic stream offset plus length cannot exceed final size · case 01

Quic stream offset plus length cannot exceed final size.

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

ROOT CAUSE

The faulty implementation uses `final is None or offset <= final` for the quic-stream-offset-plus-length-cannot-exceed-final-size decision.

VERIFIED REPAIR

Apply the explicit quic-stream-offset-plus-length-cannot-exceed-final-size contract, including the tested boundary and negative cases.

Unsuccessful approach: The attempted repair uses `offset >= 0 and length >= 0 and (final is None or offset+length < final)` and still violates a separate fixture.

Case contract

Given offset, length, final, quic stream offset plus length cannot exceed final size. Return the protocol decision or transformed value; fields are validated and fixtures state boundary outcomes.

Why this case matters

This deterministic multiplexed protocols model isolates the quic-stream-offset-plus-length-cannot-exceed-final-size 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(offset, length, final):
    return final is None or offset <= final
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(8, 3, 10), False)", "check('fixture 2', solve(8, 2, 10), True)", "check('fixture 3', solve(100, 20, None), True)", "check('fixture 4', solve(-1, 1, 10), 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`	`True`	Passed
fixture 3	`True`	`True`	Passed
fixture 4	`True`	`False`	Failed
fixture 1	`True`	`False`	Failed

SHA-256 / fe5ec7fa16acd66c9295cccc39750682a85f65c11e540b889a8f117d0a685e9a

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(offset, length, final):
    return offset >= 0 and length >= 0 and (final is None or offset+length < final)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(8, 3, 10), False)", "check('fixture 2', solve(8, 2, 10), True)", "check('fixture 3', solve(100, 20, None), True)", "check('fixture 4', solve(-1, 1, 10), 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`	`True`	Failed
fixture 3	`True`	`True`	Passed
fixture 4	`False`	`False`	Passed
fixture 1	`False`	`False`	Passed

SHA-256 / 60c87df825a218398054541746548be2505c86a8b3786a5c7d16dd1b30b3a2e3

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(offset, length, final):
    return offset >= 0 and length >= 0 and (final is None or offset+length <= final)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(8, 3, 10), False)", "check('fixture 2', solve(8, 2, 10), True)", "check('fixture 3', solve(100, 20, None), True)", "check('fixture 4', solve(-1, 1, 10), 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`	`True`	Passed
fixture 3	`True`	`True`	Passed
fixture 4	`False`	`False`	Passed
fixture 1	`False`	`False`	Passed

SHA-256 / ae01fb6fecfc4310b0de99666c340963c5a5f6298a3fea6a097df5795d93c13a

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 2026-09-29T14:38:13.263115+00:00.

Case digest / f2bfe1828fb5134c57768dbd40142c05b11f6e13c94de96cb7d55c1bcc504a71