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# -*- coding: utf-8 -*-
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 as
# published by the Free Software Foundation.
"""Generic information extractor"""
from .common import Extractor, Message
from .. import config, text
import os.path
import re
class GenericExtractor(Extractor):
"""Extractor for images in a generic web page."""
category = "generic"
directory_fmt = ("{category}", "{subcategory}", "{path}")
archive_fmt = "{imageurl}"
# By default, the generic extractor is disabled
# and the "g(eneric):" prefix in url is required.
# If the extractor is enabled, make the prefix optional
pattern = r"(?i)(?P<generic>g(?:eneric)?:)"
if config.get(("extractor", "generic"), "enabled"):
pattern += r"?"
# The generic extractor pattern should match (almost) any valid url
# Based on: https://tools.ietf.org/html/rfc3986#appendix-B
pattern += (
r"(?P<scheme>https?://)?" # optional http(s) scheme
r"(?P<domain>[-\w\.]+)" # required domain
r"(?P<path>/[^?#]*)?" # optional path
r"(?:\?(?P<query>[^#]*))?" # optional query
r"(?:\#(?P<fragment>.*))?" # optional fragment
)
example = "generic:https://www.nongnu.org/lzip/"
def __init__(self, match):
self.subcategory = match.group('domain')
Extractor.__init__(self, match)
# Strip the "g(eneric):" prefix
# and inform about "forced" or "fallback" mode
if match.group('generic'):
self.url = match.group(0).partition(":")[2]
else:
self.log.info("Falling back on generic information extractor.")
self.url = match.group(0)
# Make sure we have a scheme, or use https
if match.group('scheme'):
self.scheme = match.group('scheme')
else:
self.scheme = 'https://'
self.url = text.ensure_http_scheme(self.url, self.scheme)
self.path = match.group('path')
# Used to resolve relative image urls
self.root = self.scheme + match.group('domain')
def items(self):
"""Get page, extract metadata & images, yield them in suitable messages
Adapted from common.GalleryExtractor.items()
"""
page = self.request(self.url).text
data = self.metadata(page)
imgs = self.images(page)
try:
data["count"] = len(imgs)
except TypeError:
pass
images = enumerate(imgs, 1)
yield Message.Directory, data
for data["num"], (url, imgdata) in images:
if imgdata:
data.update(imgdata)
if "extension" not in imgdata:
text.nameext_from_url(url, data)
else:
text.nameext_from_url(url, data)
yield Message.Url, url, data
def metadata(self, page):
"""Extract generic webpage metadata, return them in a dict."""
data = {
"title" : text.extr(
page, "<title>", "</title>"),
"description" : text.extr(
page, '<meta name="description" content="', '"'),
"keywords" : text.extr(
page, '<meta name="keywords" content="', '"'),
"language" : text.extr(
page, '<meta name="language" content="', '"'),
"name" : text.extr(
page, '<meta itemprop="name" content="', '"'),
"copyright" : text.extr(
page, '<meta name="copyright" content="', '"'),
"og_site" : text.extr(
page, '<meta property="og:site" content="', '"'),
"og_site_name" : text.extr(
page, '<meta property="og:site_name" content="', '"'),
"og_title" : text.extr(
page, '<meta property="og:title" content="', '"'),
"og_description": text.extr(
page, '<meta property="og:description" content="', '"'),
}
data = {k: text.unescape(v) for k, v in data.items() if v}
data["path"] = self.path.replace("/", "")
data["pageurl"] = self.url
return data
def images(self, page):
"""Extract image urls, return a list of (image url, metadata) tuples.
The extractor aims at finding as many _likely_ image urls as possible,
using two strategies (see below); since these often overlap, any
duplicate urls will be removed at the end of the process.
Note: since we are using re.findall() (see below), it's essential that
the following patterns contain 0 or at most 1 capturing group, so that
re.findall() return a list of urls (instead of a list of tuples of
matching groups). All other groups used in the pattern should be
non-capturing (?:...).
1: Look in src/srcset attributes of img/video/source elements
See:
https://www.w3schools.com/tags/att_src.asp
https://www.w3schools.com/tags/att_source_srcset.asp
We allow both absolute and relative urls here.
Note that srcset attributes often contain multiple space separated
image urls; this pattern matches only the first url; remaining urls
will be matched by the "imageurl_pattern_ext" pattern below.
"""
imageurl_pattern_src = (
r"(?i)"
r"<(?:img|video|source)\s[^>]*" # <img>, <video> or <source>
r"src(?:set)?=[\"']?" # src or srcset attributes
r"(?P<URL>[^\"'\s>]+)" # url
)
"""
2: Look anywhere for urls containing common image/video extensions
The list of allowed extensions is borrowed from the directlink.py
extractor; other could be added, see
https://en.wikipedia.org/wiki/List_of_file_formats
Compared to the "pattern" class variable, here we must exclude also
other special characters (space, ", ', <, >), since we are looking for
urls in html tags.
"""
imageurl_pattern_ext = (
r"(?i)"
r"(?:[^?&#\"'>\s]+)" # anything until dot+extension
# dot + image/video extensions
r"\.(?:jpe?g|jpe|png|gif|web[mp]|mp4|mkv|og[gmv]|opus)"
r"(?:[^\"'<>\s]*)?" # optional query and fragment
)
imageurls_src = re.findall(imageurl_pattern_src, page)
imageurls_ext = re.findall(imageurl_pattern_ext, page)
imageurls = imageurls_src + imageurls_ext
# Resolve relative urls
#
# Image urls catched so far may be relative, so we must resolve them
# by prepending a suitable base url.
#
# If the page contains a <base> element, use it as base url
basematch = re.search(
r"(?i)(?:<base\s.*?href=[\"']?)(?P<url>[^\"' >]+)", page)
if basematch:
self.baseurl = basematch.group('url').rstrip('/')
# Otherwise, extract the base url from self.url
else:
if self.url.endswith("/"):
self.baseurl = self.url.rstrip('/')
else:
self.baseurl = os.path.dirname(self.url)
# Build the list of absolute image urls
absimageurls = []
for u in imageurls:
# Absolute urls are taken as-is
if u.startswith('http'):
absimageurls.append(u)
# // relative urls are prefixed with current scheme
elif u.startswith('//'):
absimageurls.append(self.scheme + u.lstrip('/'))
# / relative urls are prefixed with current scheme+domain
elif u.startswith('/'):
absimageurls.append(self.root + u)
# other relative urls are prefixed with baseurl
else:
absimageurls.append(self.baseurl + '/' + u)
# Remove duplicates
absimageurls = dict.fromkeys(absimageurls)
# Create the image metadata dict and add imageurl to it
# (image filename and extension are added by items())
images = [(u, {'imageurl': u}) for u in absimageurls]
return images
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