[PATCH 2/2] location-importer.in: Add Spamhaus DROP lists

["Peter Müller" <peter.mueller@ipfire.org>]

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A while ago, it was discussed whether or not libloc should become an
"opinionated database", i. e. including any information on a network's
reputation.

In general, this idea was dismissed as libloc is neither intended nor
suitable for such tasks, and we do not want to make (political?)
decisions like these for various reasons. All we do is to provide a
useful location database in a neutral way, and leave it up to our users
on how to react on certain results.

However, there is a problematic area. Take AS55303 as an example: We
_know_ this is to be a dirty network, tampering with RIR data and
hijacking IP space, and strongly recommend against processing any
connection originating from or directed to it.

Since it appears to be loaded with proxies used by miscreants for
abusive purposes, all we can do at the time of writing is to flag it
as "anonymous proxy", but we lack possibility of telling our users
something like "this is not a safe area". The very same goes for known
bulletproof ISPs, IP hijackers, and so forth.

This patch therefore suggests to populate the "is_drop" flag introduced
in libloc 0.9.8 (albeit currently unused in production) with the
contents of Spamhaus' DROP lists (https://www.spamhaus.org/drop/), to
have at least the baddest of the bad covered. The very same lists are,
in fact, included in popular IPS rulesets as well - a decent amount of
IPFire users is therefore likely to have them already enabled, but in a
very costly way.

It is not planned to go further, partly because there is no other feed
publicly available, which would come with the same intention,
volatility, and FP rate.

The second version of this patch makes use of an auxiliary function to
sanitise ASNs, hence avoiding boilerplate code, and treats any line
starting with a semicolon as a comment, which should be sufficient.

Signed-off-by: Peter Müller <peter.mueller(a)ipfire.org>
---
 src/python/location-importer.in | 104 ++++++++++++++++++++++++++++++++
 1 file changed, 104 insertions(+)

diff --git a/src/python/location-importer.in b/src/python/location-importer.in
index c2b3e41..1d84c15 100644
--- a/src/python/location-importer.in
+++ b/src/python/location-importer.in
@@ -1075,6 +1075,9 @@ class CLI(object):
 			# network allocation lists in a machine-readable format...
 			self._update_overrides_for_aws()
 
+			# Update overrides for Spamhaus DROP feeds...
+			self._update_overrides_for_spamhaus_drop()
+
 			for file in ns.files:
 				log.info("Reading %s..." % file)
 
@@ -1259,6 +1262,107 @@ class CLI(object):
 				)
 
 
+	def _update_overrides_for_spamhaus_drop(self):
+		downloader = location.importer.Downloader()
+
+		ip_urls = [
+					"https://www.spamhaus.org/drop/drop.txt",
+					"https://www.spamhaus.org/drop/edrop.txt",
+					"https://www.spamhaus.org/drop/dropv6.txt"
+				]
+
+		asn_urls = [
+					"https://www.spamhaus.org/drop/asndrop.txt"
+				]
+
+		for url in ip_urls:
+			try:
+				with downloader.request(url, return_blocks=False) as f:
+					fcontent = f.body.readlines()
+			except Exception as e:
+				log.error("Unable to download Spamhaus DROP URL %s: %s" % (url, e))
+				return
+
+			# Iterate through every line, filter comments and add remaining networks to
+			# the override table in case they are valid...
+			with self.db.transaction():
+				for sline in fcontent:
+
+					# The response is assumed to be encoded in UTF-8...
+					sline = sline.decode("utf-8")
+
+					# Comments start with a semicolon...
+					if sline.startswith(";"):
+						continue
+
+					# Extract network and ignore anything afterwards...
+					try:
+						network = ipaddress.ip_network(sline.split()[0], strict=False)
+					except ValueError:
+						log.error("Unable to parse line: %s" % sline)
+						continue
+
+					# Sanitize parsed networks...
+					if not self._check_parsed_network(network):
+						log.warning("Skipping bogus network found in Spamhaus DROP URL %s: %s" % \
+							(url, network))
+						continue
+
+					# Conduct SQL statement...
+					self.db.execute("""
+						INSERT INTO network_overrides(
+							network,
+							source,
+							is_drop
+						) VALUES (%s, %s, %s)
+						ON CONFLICT (network) DO NOTHING""",
+						"%s" % network,
+						"Spamhaus DROP lists",
+						True
+					)
+
+		for url in asn_urls:
+			try:
+				with downloader.request(url, return_blocks=False) as f:
+					fcontent = f.body.readlines()
+			except Exception as e:
+				log.error("Unable to download Spamhaus DROP URL %s: %s" % (url, e))
+				return
+
+			# Iterate through every line, filter comments and add remaining ASNs to
+			# the override table in case they are valid...
+			with self.db.transaction():
+				for sline in fcontent:
+
+					# The response is assumed to be encoded in UTF-8...
+					sline = sline.decode("utf-8")
+
+					# Comments start with a semicolon...
+					if sline.startswith(";"):
+						continue
+
+					# Extract ASN and ignore anything afterwards...
+					asn = int(sline.split()[0].strip("AS"))
+
+					# Filter invalid ASNs...
+					if not self._check_parsed_asn(asn):
+						log.warning("Skipping bogus ASN found in Spamhaus DROP URL %s: %s" % \
+							(url, asn))
+						continue
+
+					# Conduct SQL statement...
+					self.db.execute("""
+						INSERT INTO autnum_overrides(
+							number,
+							source,
+							is_drop
+						) VALUES (%s, %s, %s)
+						ON CONFLICT (number) DO NOTHING""",
+						"%s" % asn,
+						"Spamhaus ASN-DROP list",
+						True
+					)
+
 	@staticmethod
 	def _parse_bool(block, key):
 		val = block.get(key)
-- 
2.26.2