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Copy pathcheck_links.py
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747 lines (669 loc) · 25.4 KB
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#!/usr/bin/env python3
"""Safely check links declared in the FlyPython catalog directory."""
from __future__ import annotations
import argparse
import ipaddress
import json
import math
import socket
import sys
import threading
import time
from collections.abc import Callable, Iterable, Mapping
from concurrent.futures import ThreadPoolExecutor, as_completed
from dataclasses import asdict, dataclass, field
from datetime import UTC, datetime
from email.utils import parsedate_to_datetime
from pathlib import Path
from typing import Any, Protocol
from urllib.parse import urljoin, urlsplit
import requests
from requests.adapters import HTTPAdapter
from urllib3.exceptions import TimeoutError as Urllib3TimeoutError
from urllib3.util.retry import Retry
try:
from tools.catalog import (
CatalogLoadError,
canonical_hostname,
catalog_resources,
load_catalog,
validate_catalog,
)
except ModuleNotFoundError: # Direct ``python tools/check_links.py`` execution.
from catalog import (
CatalogLoadError,
canonical_hostname,
catalog_resources,
load_catalog,
validate_catalog,
)
ROOT_DIR = Path(__file__).resolve().parent.parent
DEFAULT_CATALOG = ROOT_DIR / "catalog"
DEFAULT_OUTPUT = ROOT_DIR / "reports" / "link_check_results.json"
DEFAULT_BASE_URL = "https://flypython.com/"
REVIEW_STATUS_CODES = {403, 408, 425, 429}
RETRY_STATUS_CODES = {408, 425, 429, 500, 502, 503, 504}
REDIRECT_STATUS_CODES = {301, 302, 303, 307, 308}
REPORT_STATUSES = ("working", "redirect", "review", "broken", "blocked", "error")
ACTIONABLE_STATUSES = ("review", "broken", "blocked", "error")
MAX_REDIRECTS = 5
MAX_BACKOFF_SECONDS = 5.0
KNOWN_METADATA_HOSTS = {
"instance-data",
"metadata",
"metadata.google.internal",
"metadata.google",
}
KNOWN_METADATA_IPS = {
ipaddress.ip_address("168.63.129.16"),
ipaddress.ip_address("169.254.169.254"),
ipaddress.ip_address("100.100.100.200"),
ipaddress.ip_address("fd00:ec2::254"),
}
BLOCKED_IPV6_TRANSLATION_NETWORKS = (
ipaddress.ip_network("64:ff9b::/96"),
ipaddress.ip_network("64:ff9b:1::/48"),
)
class UnsafeTarget(ValueError):
"""Raised before a request can reach a non-public network target."""
class RedirectProtocolError(requests.RequestException):
"""Raised when a redirect response cannot be followed safely."""
@dataclass(frozen=True)
class ResolvedTarget:
host: str
port: int
addresses: tuple[str, ...]
class Resolver(Protocol):
def __call__(self, host: str, port: int) -> Iterable[str]: ...
def _system_resolver(host: str, port: int) -> Iterable[str]:
for family, _, _, _, sockaddr in socket.getaddrinfo(
host, port, type=socket.SOCK_STREAM
):
if family in (socket.AF_INET, socket.AF_INET6):
yield sockaddr[0]
def _is_unsafe_ip(address: ipaddress.IPv4Address | ipaddress.IPv6Address) -> bool:
if address in KNOWN_METADATA_IPS:
return True
if (
not address.is_global
or address.is_private
or address.is_loopback
or address.is_link_local
or address.is_multicast
or address.is_reserved
or address.is_unspecified
):
return True
if isinstance(address, ipaddress.IPv6Address):
if address.ipv4_mapped or address.sixtofour or address.teredo:
return True
if any(address in network for network in BLOCKED_IPV6_TRANSLATION_NETWORKS):
return True
return False
def _is_timeout_error(error: BaseException) -> bool:
"""Recognize timeouts even when requests wraps urllib3 exceptions."""
pending: list[BaseException] = [error]
seen: set[int] = set()
timeout_types = (requests.Timeout, TimeoutError, Urllib3TimeoutError)
while pending:
current = pending.pop()
if id(current) in seen:
continue
seen.add(id(current))
if isinstance(current, timeout_types):
return True
for nested in (
current.__cause__,
current.__context__,
getattr(current, "reason", None),
*current.args,
):
if isinstance(nested, BaseException):
pending.append(nested)
return False
def _retry_delay(response: Any, attempt: int, backoff_factor: float) -> float | None:
"""Return a bounded retry delay, or ``None`` when the server asks for longer."""
raw_retry_after = response.headers.get("Retry-After")
retry_after: float | None = None
if raw_retry_after:
try:
retry_after = int(raw_retry_after.strip())
except (AttributeError, TypeError, ValueError):
try:
retry_at = parsedate_to_datetime(raw_retry_after)
if retry_at.tzinfo is None:
retry_at = retry_at.replace(tzinfo=UTC)
retry_after = (retry_at - datetime.now(UTC)).total_seconds()
except (TypeError, ValueError, OverflowError):
retry_after = None
if retry_after is not None:
retry_after = max(0.0, retry_after)
if retry_after > MAX_BACKOFF_SECONDS:
return None
return float(retry_after)
return min(backoff_factor * (2**attempt), MAX_BACKOFF_SECONDS)
class SafeTargetGuard:
"""Validate targets and return only public IPs for connection pinning."""
def __init__(self, resolver: Resolver | None = None) -> None:
self._resolver = resolver or _system_resolver
def resolve_url(self, url: str) -> ResolvedTarget:
try:
parsed = urlsplit(url)
port = parsed.port
except ValueError as exc:
raise UnsafeTarget(f"invalid URL: {exc}") from exc
if parsed.scheme.lower() not in {"http", "https"}:
raise UnsafeTarget("only HTTP and HTTPS URLs are allowed")
if parsed.username or parsed.password:
raise UnsafeTarget("URLs with credentials are not allowed")
if not parsed.hostname:
raise UnsafeTarget("URL must include a hostname")
try:
host = canonical_hostname(parsed.hostname)
except UnicodeError as exc:
raise UnsafeTarget("hostname is not valid IDNA") from exc
if host == "localhost" or host.endswith(".localhost"):
raise UnsafeTarget("localhost targets are blocked")
if host in KNOWN_METADATA_HOSTS or host.endswith(".metadata.google.internal"):
raise UnsafeTarget("cloud metadata targets are blocked")
if port == 0:
raise UnsafeTarget("port must be between 1 and 65535")
port = port or (443 if parsed.scheme.lower() == "https" else 80)
try:
literal = ipaddress.ip_address(host)
except ValueError:
try:
raw_addresses = tuple(self._resolver(host, port))
except OSError as exc:
raise requests.ConnectionError(f"DNS lookup failed for {host}: {exc}") from exc
if not raw_addresses:
raise requests.ConnectionError(f"DNS lookup returned no addresses for {host}") from None
else:
raw_addresses = (str(literal),)
addresses: set[str] = set()
for raw_address in raw_addresses:
try:
address = ipaddress.ip_address(raw_address.split("%", 1)[0])
except ValueError as exc:
raise UnsafeTarget(f"DNS returned an invalid address: {raw_address}") from exc
if _is_unsafe_ip(address):
raise UnsafeTarget(f"non-public target is blocked: {address}")
addresses.add(address.compressed)
return ResolvedTarget(host, port, tuple(sorted(addresses)))
class PinnedDNSHTTPAdapter(HTTPAdapter):
"""Pin each request hop to a validated IP to prevent DNS rebinding."""
def __init__(self, guard: SafeTargetGuard, *args: Any, **kwargs: Any) -> None:
self.guard = guard
super().__init__(*args, **kwargs)
def get_connection_with_tls_context(
self,
request: requests.PreparedRequest,
verify: bool | str,
proxies: Mapping[str, str] | None = None,
cert: Any = None,
) -> Any:
if proxies:
raise requests.ProxyError("proxies are disabled for safe link checks")
target = self.guard.resolve_url(request.url or "")
host_params, pool_kwargs = self.build_connection_pool_key_attributes(
request, verify, cert
)
scheme = str(host_params["scheme"]).lower()
original_host = target.host
display_host = f"[{original_host}]" if ":" in original_host else original_host
default_port = (scheme == "https" and target.port == 443) or (
scheme == "http" and target.port == 80
)
request.headers["Host"] = (
display_host if default_port else f"{display_host}:{target.port}"
)
host_params["host"] = target.addresses[0]
host_params["port"] = target.port
if scheme == "https":
pool_kwargs["assert_hostname"] = original_host
pool_kwargs["server_hostname"] = original_host
return self.poolmanager.connection_from_host(
**host_params, pool_kwargs=pool_kwargs
)
def build_session(guard: SafeTargetGuard) -> requests.Session:
retry = Retry(
total=0,
connect=0,
read=0,
redirect=0,
allowed_methods=frozenset({"HEAD", "GET"}),
status=0,
status_forcelist=frozenset(),
backoff_factor=0,
backoff_max=MAX_BACKOFF_SECONDS,
respect_retry_after_header=False,
raise_on_status=False,
)
adapter = PinnedDNSHTTPAdapter(
guard, max_retries=retry, pool_connections=4, pool_maxsize=4
)
session = requests.Session()
session.trust_env = False
session.headers.update(
{
"User-Agent": (
"FlyPythonCatalogLinkChecker/1.0 "
"(+https://github.com/flypythoncom/python)"
),
"Accept": "text/html,application/xhtml+xml,application/json;q=0.8,*/*;q=0.5",
}
)
session.mount("http://", adapter)
session.mount("https://", adapter)
return session
class ThreadLocalSessions:
def __init__(self, factory: Callable[[], Any]) -> None:
self._factory = factory
self._local = threading.local()
self._lock = threading.Lock()
self._sessions: list[Any] = []
def get(self) -> Any:
session = getattr(self._local, "session", None)
if session is None:
session = self._factory()
self._local.session = session
with self._lock:
self._sessions.append(session)
return session
def close_all(self) -> None:
with self._lock:
sessions, self._sessions = self._sessions, []
for session in sessions:
close = getattr(session, "close", None)
if callable(close):
close()
class HostRateLimiter:
def __init__(self, min_interval: float) -> None:
self.min_interval = min_interval
self._master_lock = threading.Lock()
self._locks: dict[str, threading.Lock] = {}
self._last_request: dict[str, float] = {}
def wait(self, url: str) -> None:
if self.min_interval <= 0:
return
host = canonical_hostname(urlsplit(url).hostname or "")
with self._master_lock:
lock = self._locks.setdefault(host, threading.Lock())
with lock:
elapsed = time.monotonic() - self._last_request.get(host, 0.0)
delay = self.min_interval - elapsed
if delay > 0:
time.sleep(delay)
self._last_request[host] = time.monotonic()
@dataclass(frozen=True)
class CatalogLink:
id: str
path: str
title: str
url: str
@dataclass
class LinkResult:
id: str
path: str
title: str
url: str
status: str
status_code: int | None = None
method: str | None = None
final_url: str | None = None
history: list[dict[str, Any]] = field(default_factory=list)
error: str | None = None
def classify_status(status_code: int, *, redirected: bool) -> str:
if 200 <= status_code < 300:
return "redirect" if redirected else "working"
if 300 <= status_code < 400:
return "redirect"
if status_code in REVIEW_STATUS_CODES or status_code >= 500:
return "review"
if 400 <= status_code < 500:
return "broken"
return "review"
class LinkChecker:
def __init__(
self,
*,
timeout: float = 10.0,
workers: int = 8,
retries: int = 2,
backoff_factor: float = 0.5,
min_interval: float = 0.2,
guard: SafeTargetGuard | None = None,
session_factory: Callable[[], Any] | None = None,
) -> None:
self.timeout = timeout
self.workers = workers
self.retries = retries
self.backoff_factor = backoff_factor
self.guard = guard or SafeTargetGuard()
factory = session_factory or (lambda: build_session(self.guard))
self.sessions = ThreadLocalSessions(factory)
self.rate_limiter = HostRateLimiter(min_interval)
def _request(
self, session: Any, method: str, url: str
) -> tuple[Any, list[dict[str, Any]]]:
current_url = url
history: list[dict[str, Any]] = []
attempt = 0
while True:
get_adapter = getattr(session, "get_adapter", None)
adapter = get_adapter(current_url) if callable(get_adapter) else None
if not isinstance(adapter, PinnedDNSHTTPAdapter):
self.guard.resolve_url(current_url)
self.rate_limiter.wait(current_url)
kwargs: dict[str, Any] = {
"timeout": self.timeout,
"allow_redirects": False,
"stream": True,
}
try:
response = (
session.get(current_url, **kwargs)
if method == "GET"
else session.head(current_url, **kwargs)
)
except requests.RequestException as exc:
retryable = _is_timeout_error(exc) or isinstance(
exc, requests.ConnectionError
)
terminal = isinstance(
exc,
(
requests.exceptions.InvalidURL,
requests.exceptions.ProxyError,
requests.exceptions.SSLError,
),
)
if terminal or not retryable or attempt >= self.retries:
raise
delay = min(
self.backoff_factor * (2**attempt), MAX_BACKOFF_SECONDS
)
attempt += 1
if delay > 0:
time.sleep(delay)
continue
if (
response.status_code in RETRY_STATUS_CODES
and attempt < self.retries
):
delay = _retry_delay(
response,
attempt,
self.backoff_factor,
)
if delay is None:
return response, history
response.close()
attempt += 1
if delay > 0:
time.sleep(delay)
continue
location = response.headers.get("Location")
if not 300 <= response.status_code < 400:
return response, history
if response.status_code not in REDIRECT_STATUS_CODES:
response.close()
raise RedirectProtocolError(
f"unsupported redirect status {response.status_code}"
)
if not location:
if method == "HEAD":
return response, history
response.close()
raise RedirectProtocolError(
f"redirect status {response.status_code} has no Location header"
)
try:
if len(history) >= MAX_REDIRECTS:
raise requests.TooManyRedirects(
f"more than {MAX_REDIRECTS} redirects"
)
next_url = urljoin(current_url, location)
if (
urlsplit(current_url).scheme.lower() == "https"
and urlsplit(next_url).scheme.lower() == "http"
):
raise UnsafeTarget("HTTPS redirects may not downgrade to HTTP")
history.append(
{
"status_code": response.status_code,
"url": current_url,
"location": location,
}
)
finally:
response.close()
current_url = next_url
attempt = 0
def check_one(self, link: CatalogLink) -> LinkResult:
try:
session = self.sessions.get()
head, head_history = self._request(session, "HEAD", link.url)
try:
if (
head.status_code < 300
or head.status_code in REVIEW_STATUS_CODES
or head.status_code >= 500
):
return LinkResult(
link.id,
link.path,
link.title,
link.url,
classify_status(
head.status_code, redirected=bool(head_history)
),
status_code=head.status_code,
method="HEAD",
final_url=head.url,
history=head_history,
)
finally:
head.close()
response, get_history = self._request(session, "GET", link.url)
try:
return LinkResult(
link.id,
link.path,
link.title,
link.url,
classify_status(
response.status_code, redirected=bool(get_history)
),
status_code=response.status_code,
method="GET",
final_url=response.url,
history=get_history,
)
finally:
response.close()
except UnsafeTarget as exc:
return LinkResult(
link.id, link.path, link.title, link.url, "blocked", error=str(exc)
)
except requests.RequestException as exc:
if _is_timeout_error(exc):
return LinkResult(
link.id,
link.path,
link.title,
link.url,
"review",
error=f"timeout: {exc}",
)
return LinkResult(
link.id,
link.path,
link.title,
link.url,
"error",
error=f"request failed: {exc}",
)
except Exception as exc: # Surface checker defects without aborting other workers.
return LinkResult(
link.id,
link.path,
link.title,
link.url,
"error",
error=f"unexpected checker error: {exc}",
)
def check_all(self, links: Iterable[CatalogLink]) -> list[LinkResult]:
link_list = list(links)
results: list[LinkResult] = []
try:
with ThreadPoolExecutor(max_workers=self.workers) as executor:
futures = {
executor.submit(self.check_one, link): link for link in link_list
}
for future in as_completed(futures):
results.append(future.result())
finally:
self.sessions.close_all()
return sorted(results, key=lambda result: (result.path, result.id, result.url))
def select_links(
data: Mapping[str, Any], *, mode: str, base_url: str
) -> list[CatalogLink]:
base_host = canonical_hostname(urlsplit(base_url).hostname or "")
links: list[CatalogLink] = []
for resource in catalog_resources(data):
raw_url = str(resource.get("url", ""))
absolute_url = urljoin(base_url, raw_url)
host = canonical_hostname(urlsplit(absolute_url).hostname or "")
is_internal = host == base_host
if mode == "internal" and not is_internal:
continue
if mode == "external" and is_internal:
continue
links.append(
CatalogLink(
id=str(resource.get("id", "")),
path=str(resource.get("path", "")),
title=str(resource.get("title", "")),
url=absolute_url,
)
)
return links
def build_report(
*, catalog: Path, mode: str, results: list[LinkResult]
) -> dict[str, Any]:
counts = {
status: sum(item.status == status for item in results)
for status in REPORT_STATUSES
}
counts["total"] = len(results)
return {
"schema_version": 1,
"generated_at": datetime.now(UTC).isoformat(),
"catalog": str(catalog),
"mode": mode,
"counts": counts,
"results": [asdict(result) for result in results],
}
def exit_code_for_report(report: Mapping[str, Any]) -> int:
if not isinstance(report, Mapping):
return 2
counts = report.get("counts", {})
if not isinstance(counts, Mapping):
return 2
expected_keys = {*REPORT_STATUSES, "total"}
if set(counts) != expected_keys:
return 2
values = [counts[status] for status in REPORT_STATUSES]
total = counts["total"]
if (
not isinstance(total, int)
or isinstance(total, bool)
or total <= 0
or any(
not isinstance(value, int) or isinstance(value, bool) or value < 0
for value in values
)
or sum(values) != total
):
return 2
if any(counts[status] for status in ACTIONABLE_STATUSES):
return 1
return 0
def _positive_float(value: str) -> float:
parsed = float(value)
if not math.isfinite(parsed) or parsed <= 0:
raise argparse.ArgumentTypeError("must be a finite number greater than zero")
return parsed
def _non_negative_float(value: str) -> float:
parsed = float(value)
if not math.isfinite(parsed) or parsed < 0:
raise argparse.ArgumentTypeError("must be a finite number zero or greater")
return parsed
def _workers(value: str) -> int:
parsed = int(value)
if not 1 <= parsed <= 32:
raise argparse.ArgumentTypeError("must be between 1 and 32")
return parsed
def build_parser() -> argparse.ArgumentParser:
parser = argparse.ArgumentParser(description=__doc__)
parser.add_argument("--catalog", type=Path, default=DEFAULT_CATALOG)
mode = parser.add_mutually_exclusive_group()
mode.add_argument("--mode", choices=("internal", "external", "all"), default="all")
mode.add_argument("--internal", action="store_const", const="internal", dest="mode")
mode.add_argument("--external", action="store_const", const="external", dest="mode")
mode.add_argument("--all", action="store_const", const="all", dest="mode")
parser.add_argument("--base-url", default=DEFAULT_BASE_URL)
parser.add_argument(
"--output", default=str(DEFAULT_OUTPUT), help="JSON path, or '-' for stdout"
)
parser.add_argument("--timeout", type=_positive_float, default=10.0)
parser.add_argument("--workers", type=_workers, default=8)
parser.add_argument("--retries", type=int, default=2)
parser.add_argument("--backoff", type=_non_negative_float, default=0.5)
parser.add_argument("--min-interval", type=_non_negative_float, default=0.2)
return parser
def run(argv: list[str] | None = None) -> int:
args = build_parser().parse_args(argv)
if args.retries < 0:
print("--retries must be zero or greater", file=sys.stderr)
return 2
try:
data = load_catalog(args.catalog)
except CatalogLoadError as exc:
print(str(exc), file=sys.stderr)
return 2
issues = validate_catalog(data)
if issues:
print("catalog validation failed before link checks", file=sys.stderr)
for issue in issues:
print(f"{issue.location}: {issue.code}: {issue.message}", file=sys.stderr)
return 2
links = select_links(data, mode=args.mode, base_url=args.base_url)
checker = LinkChecker(
timeout=args.timeout,
workers=args.workers,
retries=args.retries,
backoff_factor=args.backoff,
min_interval=args.min_interval,
)
results = checker.check_all(links)
report = build_report(catalog=args.catalog, mode=args.mode, results=results)
payload = json.dumps(report, ensure_ascii=False, indent=2) + "\n"
if args.output == "-":
sys.stdout.write(payload)
else:
output = Path(args.output)
output.parent.mkdir(parents=True, exist_ok=True)
output.write_text(payload, encoding="utf-8")
print(f"link report: {output}", file=sys.stderr)
counts = report["counts"]
print(
"links: " + ", ".join(f"{key}={value}" for key, value in counts.items()),
file=sys.stderr,
)
return exit_code_for_report(report)
def main() -> None:
raise SystemExit(run())
if __name__ == "__main__":
main()