importer: Change download behaviour

The downloader used to open a connection to the web server hosting our
content which would have been decompressed (if necessary) on the fly and
also been parsed on the fly so that it could have been fed into the
database easily.

Some webservers do not seem to be patient enough to keep the connection
open if things take a little bit longer than usual. That caused the
import to fail.

This patch changes the behaviour that we would download all content
first, store it locally, and then start processing it.

Fixes: #12852
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>
Cc: Peter Müller <peter.mueller@ipfire.org>

src/python/location/importer.py

@@ -19,6 +19,7 @@
 
 import gzip
 import logging
+import tempfile
 import urllib.request
 
 # Initialise logging
@@ -106,75 +107,76 @@ class Downloader(object):
 		log.info("Using proxy %s" % url)
 		self.proxy = url
 
-	def request(self, url, data=None, return_blocks=False):
+	def retrieve(self, url, data=None):
+		"""
+			This method will fetch the content at the given URL
+			and will return a file-object to a temporary file.
+
+			If the content was compressed, it will be decompressed on the fly.
+		"""
+		# Open a temporary file to buffer the downloaded content
+		t = tempfile.SpooledTemporaryFile(max_size=100 * 1024 * 1024)
+
+		# Create a new request
 		req = urllib.request.Request(url, data=data)
 
 		# Configure proxy
 		if self.proxy:
 			req.set_proxy(self.proxy, "http")
 
-		return DownloaderContext(self, req, return_blocks=return_blocks)
-
-
-class DownloaderContext(object):
-	def __init__(self, downloader, request, return_blocks=False):
-		self.downloader = downloader
-		self.request = request
-
-		# Should we return one block or a single line?
-		self.return_blocks = return_blocks
-
-		# Save the response object
-		self.response = None
-
-	def __enter__(self):
-		log.info("Retrieving %s..." % self.request.full_url)
+		log.info("Retrieving %s..." % req.full_url)
 
 		# Send request
-		self.response = urllib.request.urlopen(self.request)
+		res = urllib.request.urlopen(req)
 
 		# Log the response headers
 		log.debug("Response Headers:")
-		for header in self.headers:
-			log.debug("	%s: %s" % (header, self.get_header(header)))
-
-		return self
+		for header in res.headers:
+			log.debug("	%s: %s" % (header, res.headers[header]))
+
+		# Write the payload to the temporary file
+		with res as f:
+			while True:
+				buf = f.read(65536)
+				if not buf:
+					break
 
-	def __exit__(self, type, value, traceback):
-		pass
+				t.write(buf)
 
-	def __iter__(self):
-		"""
-			Makes the object iterable by going through each block
-		"""
-		if self.return_blocks:
-			return iterate_over_blocks(self.body)
+		# Rewind the temporary file
+		t.seek(0)
 
-		return iterate_over_lines(self.body)
+		# Fetch the content type
+		content_type = res.headers.get("Content-Type")
 
-	@property
-	def headers(self):
-		if self.response:
-			return self.response.headers
+		# Decompress any gzipped response on the fly
+		if content_type in ("application/x-gzip", "application/gzip"):
+			t = gzip.GzipFile(fileobj=t, mode="rb")
 
-	def get_header(self, name):
-		if self.headers:
-			return self.headers.get(name)
+		# Return the temporary file handle
+		return t
 
-	@property
-	def body(self):
+	def request_blocks(self, url, data=None):
 		"""
-			Returns a file-like object with the decoded content
-			of the response.
+			This method will fetch the data from the URL and return an
+			iterator for each block in the data.
 		"""
-		content_type = self.get_header("Content-Type")
+		# Download the data first
+		t = self.retrieve(url, data=data)
 
-		# Decompress any gzipped response on the fly
-		if content_type in ("application/x-gzip", "application/gzip"):
-			return gzip.GzipFile(fileobj=self.response, mode="rb")
+		# Then, split it into blocks
+		return iterate_over_blocks(t)
+
+	def request_lines(self, url, data=None):
+		"""
+			This method will fetch the data from the URL and return an
+			iterator for each line in the data.
+		"""
+		# Download the data first
+		t = self.retrieve(url, data=data)
 
-		# Return the response by default
-		return self.response
+		# Then, split it into lines
+		return iterate_over_lines(t)
 
 
 def read_blocks(f):

src/scripts/location-importer.in

@@ -435,8 +435,7 @@ class CLI(object):
 
 			for source_key in location.importer.WHOIS_SOURCES:
 				for single_url in location.importer.WHOIS_SOURCES[source_key]:
-					with downloader.request(single_url, return_blocks=True) as f:
-						for block in f:
+					for block in downloader.request_blocks(single_url):
 						self._parse_block(block, source_key, validcountries)
 
 			# Process all parsed networks from every RIR we happen to have access to,
@@ -518,8 +517,7 @@ class CLI(object):
 			for single_url in location.importer.EXTENDED_SOURCES[source_key]:
 				with self.db.transaction():
 					# Download data
-					with downloader.request(single_url) as f:
-						for line in f:
+					for line in downloader.request_lines(single_url):
 						self._parse_line(line, source_key, validcountries)
 
 		# Download and import (technical) AS names from ARIN
@@ -871,12 +869,8 @@ class CLI(object):
 		# technical, not intended for human consumption, as description fields in
 		# organisation handles for other RIRs are - however, this is what we have got,
 		# and in some cases, it might be still better than nothing)
-		with downloader.request("https://ftp.arin.net/info/asn.txt", return_blocks=False) as f:
-			for line in f:
-				# Convert binary line to string...
-				line = str(line)
-
-				# ... valid lines start with a space, followed by the number of the Autonomous System ...
+		for line in downloader.request_lines("https://ftp.arin.net/info/asn.txt"):
+			# Valid lines start with a space, followed by the number of the Autonomous System ...
 			if not line.startswith(" "):
 				continue
 
@@ -1262,8 +1256,11 @@ class CLI(object):
 		downloader = location.importer.Downloader()
 
 		try:
-			with downloader.request("https://ip-ranges.amazonaws.com/ip-ranges.json", return_blocks=False) as f:
-				aws_ip_dump = json.load(f.body)
+			# Fetch IP ranges
+			f = downloader.retrieve("https://ip-ranges.amazonaws.com/ip-ranges.json")
+
+			# Parse downloaded file
+			aws_ip_dump = json.load(f)
 		except Exception as e:
 			log.error("unable to preprocess Amazon AWS IP ranges: %s" % e)
 			return
@@ -1386,12 +1383,11 @@ class CLI(object):
 				]
 
 		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
+			# Fetch IP list
+			f = downloader.retrieve(url)
+
+			# Split into lines
+			fcontent = f.readlines()
 
 			# Conduct a very basic sanity check to rule out CDN issues causing bogus DROP
 			# downloads.
@@ -1408,7 +1404,6 @@ class CLI(object):
 			# 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")
 
@@ -1443,18 +1438,13 @@ class CLI(object):
 					)
 
 		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
+			# Fetch URL
+			f = downloader.retrieve(url)
 
 			# 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:
-
+				for sline in t.readlines():
 					# The response is assumed to be encoded in UTF-8...
 					sline = sline.decode("utf-8")