FA-7571 / Multiplexed protocols / Open access
Quic amplification budget applies before address validation · case 01
Quic amplification budget applies before address validation.
ROOT CAUSE
The faulty implementation uses `max(0,3*received-sent)` for the quic-amplification-budget-applies-before-address-validation decision.
VERIFIED REPAIR
Apply the explicit quic-amplification-budget-applies-before-address-validation contract, including the tested boundary and negative cases.
Unsuccessful approach: The attempted repair uses `None if validated else 3*received` and still violates a separate fixture.
Case contract
Bounded offline decision model: quic amplification budget applies before address validation. Inputs are already validated protocol fields; the explicit fixtures define the supported policy, not a complete protocol implementation.
Why this case matters
This deterministic multiplexed protocols model isolates the quic-amplification-budget-applies-before-address-validation 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(received, sent, validated):
return max(0,3*received-sent)
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(10, 20, False), 10)", "check('fixture 2', solve(10, 40, False), 0)", "check('fixture 3', solve(0, 0, True), None)", "check('fixture 4', solve(10, 0, False), 30)"]
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 | 0 | 0 | Passed |
| fixture 3 | 0 | None | Failed |
| fixture 4 | 30 | 30 | Passed |
| fixture 1 | 10 | 10 | Passed |
SHA-256 / d02f9bcd2fcc061ec939b33091241c51b85b296744495ce3a8cfc3c01973ae8a
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(received, sent, validated):
return None if validated else 3*received
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(10, 20, False), 10)", "check('fixture 2', solve(10, 40, False), 0)", "check('fixture 3', solve(0, 0, True), None)", "check('fixture 4', solve(10, 0, False), 30)"]
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 | 30 | 0 | Failed |
| fixture 3 | None | None | Passed |
| fixture 4 | 30 | 30 | Passed |
| fixture 1 | 30 | 10 | Failed |
SHA-256 / c0af729caed6635aab62cb3745ffafd8ef6786d50f52fe74770e572377ef2c21
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(received, sent, validated):
return None if validated else max(0,3*received-sent)
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(10, 20, False), 10)", "check('fixture 2', solve(10, 40, False), 0)", "check('fixture 3', solve(0, 0, True), None)", "check('fixture 4', solve(10, 0, False), 30)"]
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 | 0 | 0 | Passed |
| fixture 3 | None | None | Passed |
| fixture 4 | 30 | 30 | Passed |
| fixture 1 | 10 | 10 | Passed |
SHA-256 / 719bdcef3bebf3b41dd1860db3ee6a4f1a464cf1600a75a459596153f6684db0
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 2026-09-29T14:38:13.304981+00:00.
Case digest / 8381d510f5dd194a2f3434e7f368a87463c0cf5aa5997c9793e9bf816bb6cb43