FA-7051 / Proxy forwarding / Open access

Proxy bypass host suffix requires domain boundary · case 01

Proxy bypass host suffix requires domain boundary.

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

ROOT CAUSE

The faulty implementation uses `host.endswith(suffix)` for the proxy-bypass-host-suffix-requires-domain-boundary decision.

VERIFIED REPAIR

Apply the explicit proxy-bypass-host-suffix-requires-domain-boundary contract, including the tested boundary and negative cases.

Unsuccessful approach: The attempted repair uses `host == suffix` and still violates a separate fixture.

Case contract

Bounded offline decision model: proxy bypass host suffix requires domain boundary. Inputs are already validated protocol fields; the explicit fixtures define the supported policy, not a complete protocol implementation.

Why this case matters

This deterministic proxy forwarding model isolates the proxy-bypass-host-suffix-requires-domain-boundary 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(host, suffix):
    return host.endswith(suffix)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve('badexample.com', 'example.com'), False)", "check('fixture 2', solve('a.example.com', 'example.com'), True)", "check('fixture 3', solve('example.com', 'example.com'), True)", "check('fixture 4', solve('else.com', 'example.com'), 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	`True`	`False`	Failed

SHA-256 / 96062a5f653fdbe3bc41a3dd0494f6a789d670e104eb0b2be9eeda18f39dc733

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(host, suffix):
    return host == suffix
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve('badexample.com', 'example.com'), False)", "check('fixture 2', solve('a.example.com', 'example.com'), True)", "check('fixture 3', solve('example.com', 'example.com'), True)", "check('fixture 4', solve('else.com', 'example.com'), 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 / 2f150456f7b0969be91a3c283ad369b4ad99cb7234c4a1916539f10855bfe357

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(host, suffix):
    return host == suffix or host.endswith("."+suffix)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve('badexample.com', 'example.com'), False)", "check('fixture 2', solve('a.example.com', 'example.com'), True)", "check('fixture 3', solve('example.com', 'example.com'), True)", "check('fixture 4', solve('else.com', 'example.com'), 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 / 0591eb8797339ecfb649d8913618cd599241674db0b5d3a45a9898d8b49851c1

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 2026-09-29T14:38:07.886903+00:00.

Case digest / 3d9107d892357cc821dce4ab44027274e8919d285bbcf7ac8f20b0397f92c9e2