Re: [PATCH v3 1/2] location-importer: Introduce auxiliary function to sanitise ASNs

[Michael Tremer <michael.tremer@ipfire.org>]

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Hello,

> On 23 Oct 2021, at 08:15, Peter Müller <peter.mueller(a)ipfire.org> wrote:
> 
> The second version of this patch does this in a more Pythonic way.

Hmm, almost.

> Signed-off-by: Peter Müller <peter.mueller(a)ipfire.org>
> ---
> src/python/location-importer.in | 19 +++++++++++++++++--
> 1 file changed, 17 insertions(+), 2 deletions(-)
> 
> diff --git a/src/python/location-importer.in b/src/python/location-importer.in
> index da058d3..3ad335f 100644
> --- a/src/python/location-importer.in
> +++ b/src/python/location-importer.in
> @@ -574,6 +574,21 @@ class CLI(object):
> 		# be suitable for libloc consumption...
> 		return True
> 
> +	def _check_parsed_asn(self, asn):
> +		"""
> +			Assistive function to filter Autonomous System Numbers not being suitable
> +			for adding to our database. Returns False in such cases, and True otherwise.
> +		"""
> +
> +		validranges = ((1,23455), (23457,64495), (131072, 4199999999))

This should be defined at the top of the file. Otherwise, Python will create and destroy a tuple with these values every time the function is being called. That is a lot of overhead.

I also like writing lists like this as follows:

VALID_ASN_RANGES = (
	(1, 23455),
	(23457, 64495),
	...
)

That way, changes are easier to read in a diff.

> +
> +		for singlerange in validranges:

You can write this as “for first, last in validranges:”. That way, you have a new variable that expresses what it is all about.

> +			if singlerange[0] <= asn and singlerange[1] >= asn:
> +				return True
> +
> +		log.info("Supplied ASN %s out of publicly routable ASN ranges" % asn)
> +		return False
> +
> 	def _parse_block(self, block, source_key, validcountries = None):
> 		# Get first line to find out what type of block this is
> 		line = block[0]
> @@ -829,8 +844,8 @@ class CLI(object):
> 					log.debug("Skipping ARIN AS names line not containing an integer for ASN")
> 					continue
> 
> -				if not ((1 <= asn and asn <= 23455) or (23457 <= asn and asn <= 64495) or (131072 <= asn and asn <= 4199999999)):
> -					log.debug("Skipping ARIN AS names line not containing a valid ASN: %s" % asn)
> +				# Filter invalid ASNs...
> +				if not self._check_parsed_asn(asn):
> 					continue
> 
> 				# Skip any AS name that appears to be a placeholder for a different RIR or entity...
> -- 
> 2.26.2