merge: testing → main (reconcile 2-week divergence)

decnet/asn/iptoasn/fetch.py

@@ -0,0 +1,63 @@
+"""iptoasn.com bulk dump download.
+
+One file: ``ip2asn-v4.tsv.gz``, ~5 MB compressed, refreshed daily.
+Pulled over HTTPS with the same generic UA the geoip RIR fetcher uses
+(stealth: never identify as DECNET — public-data scrapers correlated to
+honeypot operator egress is the threat model).
+"""
+from __future__ import annotations
+
+import logging
+import shutil
+import urllib.request
+from pathlib import Path
+from typing import Tuple
+
+logger = logging.getLogger("decnet.asn.iptoasn.fetch")
+
+# Mirror the (name, url) tuple shape of geoip.rir.fetch so test
+# harnesses can swap one for the other.
+IPTOASN_SOURCES: Tuple[Tuple[str, str], ...] = (
+    ("ip2asn-v4", "https://iptoasn.com/data/ip2asn-v4.tsv.gz"),
+)
+
+# Generic UA — matches geoip.rir.fetch. iptoasn.com explicitly releases
+# the data into the public domain and does NOT require an identifying UA,
+# so we keep DECNET stealth instead of advertising.
+_USER_AGENT = "Mozilla/5.0 (compatible; fetch/1.0)"
+_TIMEOUT_S = 60
+
+
+def fetch_all(dest: Path) -> list[Path]:
+    """Download every iptoasn file into *dest*. Returns the written paths.
+
+    Atomic per file: download to ``{name}.tsv.gz.tmp`` then rename. A
+    partial failure leaves the previous generation intact.
+    """
+    dest.mkdir(parents=True, exist_ok=True)
+    written: list[Path] = []
+    for name, url in IPTOASN_SOURCES:
+        target = dest / f"{name}.tsv.gz"
+        tmp = target.with_suffix(".gz.tmp")
+        try:
+            _download(url, tmp)
+            tmp.replace(target)
+            written.append(target)
+            logger.info(
+                "asn.iptoasn: fetched %s (%d bytes)",
+                name, target.stat().st_size,
+            )
+        except Exception as exc:
+            logger.error(
+                "asn.iptoasn: fetch failed for %s (%s): %s", name, url, exc
+            )
+            if tmp.exists():
+                tmp.unlink(missing_ok=True)
+            # Keep any stale previous file — better outdated than empty.
+    return written
+
+
+def _download(url: str, dest: Path) -> None:
+    req = urllib.request.Request(url, headers={"User-Agent": _USER_AGENT})
+    with urllib.request.urlopen(req, timeout=_TIMEOUT_S) as resp, dest.open("wb") as fh:  # nosec B310 — fixed https iptoasn URL
+        shutil.copyfileobj(resp, fh)