File asn_get_routeviews.py of Package apache2-mod_asn

#!/usr/bin/env python

import os, os.path
import sys
import time
import urllib

# the data snapshot that we need is put into monthly directories, like this:
# example url: 'http://archive.routeviews.org/oix-route-views/2008.11/oix-full-snapshot-latest.dat.bz2'

filename = 'oix-full-snapshot-latest.dat.bz2'
url = 'http://archive.routeviews.org/oix-route-views/%s/%s' \
        % (time.strftime("%Y.%m", time.gmtime()), filename)

if not os.path.exists(filename):
    print >>sys.stderr, 'downloading', url
    urllib.urlretrieve(url, filename=filename)

if time.time() - os.path.getmtime(filename) > 60 * 60 * 24 * 7:
    sys.exit('File older than 1 week - remove it to have it downloaded again')

def gen_open(filenames): 
    """Open a sequence of filenames"""
    import gzip, bz2 
    for name in filenames: 
        if name.endswith(".gz"): 
             yield gzip.open(name) 
        elif name.endswith(".bz2"): 
             yield bz2.BZ2File(name) 
        else: 
             yield open(name)

def gen_cat(sources): 
    """Concatenate items from one or more 
    source into a single sequence of items"""
    for s in sources: 
        for item in s: 
            yield item.rstrip()

def gen_lines(lines): 
    """Some lines come broken in two lines, like this:

*  63.105.200.0/21  203.181.248.168          0      0      0 7660 2516 703 9848 9957 i
    *  63.105.202.0/27  203.62.252.186           0      0      0 1221 4637 4766 9318 9957 9957 9286 i
    *  63.105.204.128/25
                         203.62.252.186           0      0      0 1221 4637 4766 9318 9957 i
    *  63.105.205.0/25  203.62.252.186           0      0      0 1221 4637 4766 9318 9957 i
    *  63.105.207.144/28
                         203.62.252.186           0      0      0 1221 4637 4766 9318 9957 9957 9286 i
    *  63.105.248.0/21  196.7.106.245            0      0      0 2905 701 19830 i

This generator puts them together, and outputs them on one line.
    """
    lastline = ''
    for line in lines: 
        if len(line) > 35: 
            if lastline:
                #print 'last:', lastline
                #print 'line:', line
                yield lastline + line
            else:
                yield line
            lastline = ''
        else:
            lastline = line

def gen_grep(patc, lines): 
    """Generate a sequence of lines that contain 
    a given regular expression"""
    for line in lines: 
        if '{' in line:
            continue
        if patc.search(line): yield line

def gen_asn(lines): 
    """Generate a sequence of lines that end in 'i'
    and return the first, third last and second word for each of them.

Complain if a line doesn't end in 'i'.

For prefix 0.0.0.0/0, we don't return AS number 286 - but rather zero,
    because this is more meaningful later. An AS with number 0 doesn't exist.
    0.0.0.0/0 will be the prefix that contains 127.0.0.1.

In routeviews data, 0.0.0.0/0 seems to be listed with a random (changing)
    AS number, which seems like an artifact.
    """
    for line in lines: 
        s = line.split()
        if s[-1] != 'i':
            print >>sys.stderr, repr(line)
            sys.exit('Error: this is unusal, line ends in %r, not \'i\'' % s[-1])
        if s[1].startswith('0.0.0.0/0'):
            # see comment above
            yield s[1], '0', '0'
        # drop the 'i' at the end
        s.pop()
        # drop doublettes of the as number at the end
        while s[-1] == s[-2]:
            s.pop()
        yield s[1], s[-2], s[-1]

# not used here, but useful another time maybe...
def gen_uniq(lines): 
    """Generate a sequence of lines that filters
    lines that are identical to the line before"""
    lastline = ''
    for line in lines: 
        if line != lastline:
            yield line
        lastline = line

def gen_firstuniq(tupls): 
    """Generate a sequence of tuples that filters
    tuples where the first word is the same as on the line above"""
    last = ''
    for tupl in tupls:

if tupl[0] != last:
            yield tupl

last = tupl[0]

def main():
    """
    Create a generator pipeline and process 900 MB's worth of routeviews data.

You can directly process the bz2 or gz compressed file. If you unpack it
    before, it can be a few times faster, but the uncompressed data is nearly a
    GB in size (2008).

The output format is, for each line:

prefix asnpeer asn

Usage: get_routeviews [oix.dat[.gz|.bz2]]

Will read an existing file named 'oix-full-snapshot-latest.dat.bz2' if no
    argument is given.

If the file is older than 1 week, the script will suggest to download it
    again. It'll automatically do so if you remove the file.
    """
    import re

pat = r'^\*'
    patc = re.compile(pat)

global filename
    filename = [filename]
    if len(sys.argv[1:]):
        filename = [sys.argv[1]]

try:

oixfile     = gen_open(filename)
        oixlines    = gen_cat(oixfile)
        fixedlines  = gen_lines(oixlines)
        patlines    = gen_grep(patc, fixedlines)
        pfxasn      = gen_asn(patlines)
        pfxasn_uniq = gen_firstuniq(pfxasn)

for pfx, asnb, asn in pfxasn_uniq:
            print pfx, asnb, asn

except KeyboardInterrupt:
        sys.exit('interrupted!')
    except IOError, e:
        sys.exit(e)

if __name__ == '__main__':
    main()