crawl.py

#!/usr/bin/env python2

import cStringIO
import formatter
from htmllib import HTMLParser
import httplib
import os
import sys
import urllib
import urlparse

class Retriever(object):
    __slots__  = ('url', 'file')
    def __init__(self, url):
        self.url, self.file = self.get_file(url)
    
    def get_file(self, url, default='index.html'):
        """Create usable local filename from URL"""
        parsed = urlparse.urlparse(url)
        host = parsed.netloc.split('@')[-1].split(':')[0]
        filepath = '%s%s' % (host, parsed.path)
        if not os.path.splitext(parsed.path)[1]:
            filepath = os.path.join(filepath, default)
        linkdir = os.path.dirname(filepath)
        if not os.path.isdir(linkdir):
            if os.path.exists(linkdir):
                os.unlink(linkdir)
            os.makedirs(linkdir)
        return url, filepath

    def download(self):
        """Download URL to specific named file"""
        try:
            retval = urllib.urlretrieve(self.url, self.file)
        except (IOError, httplib.InvalidURL) as e:
            retval = (('*** ERROR: bad URL "%s": %s' % 
            (self.url, e)),)
        return retval

    def parse_links(self):
        """Parse out the links found in downloaded HTML file"""
        f = open(self.file, 'r')
        data = f.read()
        f.close()
        parser = HTMLParser(formatter.AbstractFormatter(
            formatter.DumbWriter(cStringIO.StringIO())))
        parser.feed(data)
        parser.close()
        return parser.anchorlist

class Crawler(object):
    count = 0

    def __init__(self, url):
        self.q = [url]
        self.seen = set()
        parsed = urlparse.urlparse(url)
        host = parsed.netloc.split('@')[-1].split(':')[0]
        self.dom = '.'.join(host.split('.')[-2:])

    def get_page(self, url, media=False):
        """Download page & parse links, add to queue if nec"""
        r = Retriever(url)
        fname = r.download()[0]
        if fname[0] == '*':
            print fname, '... skipping parse'
            return
        Crawler.count += 1
        print '\n', Crawler.count, ')'
        print 'URL:', url
        print 'FILE:', fname
        self.seen.add(url)
        ftype = os.path.splitext(fname)[1]
        if ftype not in ('.htm', '.html'):
            return

        for link in r.parse_links():
            if link.startswith('mailto:'):
                print '... discarded, mailto link'
                continue
            if not media:
                ftype = os.path.splitext(link)[1]
                if ftype in ('.mp3', '.mp4', '.m4v', '.wav'):
                    print '... discarded, media file'
                    continue
            if not link.startswith('http://'):
                link = urlparse.urljoin(url, link)
            print '*', link,
            if link not in self.seen:
                if self.dom not in link:
                    print '... discarded, not in domain'
                else:
                    if link not in self.q:
                        self.q.append(link)
                        print '... new, added to Q'
                    else:
                        print '... discarded, already in Q'
            else:
                print '... discarded, already processed'

    def go(self, media=False):
        """Process next page in queue (if any)"""
        while self.q:
            url = self.q.pop()
            self.get_page(url, media)

def main():
    if len(sys.argv) > 1:
        url = sys.argv[1]
    else:
        try:
            url = raw_input('Enter starting URL: ')
        except (KeyboardInterrupt, EOFError):
            url = ''
    if not url:
        return
    if not url.startswith('http://') and \
        not url.startswith('ftp://'):
            url = 'http://%s/' % url
    robot = Crawler(url)
    robot.go()

if __name__ == '__main__':
    main()