Python 3 data url handler

dataurl.py

import binascii
import urllib.request
import urllib.parse
import email.message
import io

__all__ = ['parse_data_url','DataResponse','DataHandler']

def parse_data_url(url):
	scheme, data = url.split(":",1)
	assert scheme == "data", "unsupported scheme: "+scheme
	mediatype, data = data.split(",",1)
	# base64 urls might have a padding which might (should) be quoted:
	data = urllib.parse.unquote_to_bytes(data)
	if mediatype.endswith(";base64"):
		return binascii.a2b_base64(data), mediatype[:-7] or None
	else:
		return data, mediatype or None

# DataResponse exposes the mediatype and emulates some methods/properties of
# HTTPResponse: msg, headers, length, info, geturl, getheader and getheaders
class DataResponse(io.BytesIO):
	__slots__ = 'url','mediatype','msg','headers','length'
	def __init__(self,url):
		data, mediatype = parse_data_url(url)
		io.BytesIO.__init__(self,data)
		self.url = url
		self.mediatype = mediatype
		self.length = len(data)
		self.headers = self.msg = email.message.Message()
		if mediatype is not None:
			self.msg.add_header("Content-Type",mediatype)
	
	def getheader(self,name,default=None):
		headers = self.headers.get_all(name) or default
		if isinstance(headers, str) or not hasattr(headers, '__iter__'):
			return headers
		else:
			return ', '.join(headers)
	
	def getheaders(self):
		return list(self.headers.items())
	
	def geturl(self):
		return self.url
	
	def info(self):
		return self.headers

class DataHandler(urllib.request.BaseHandler):
	def data_open(self, req):
		return DataResponse(req.full_url)

dataurl_simple.py

import binascii
import urllib.request
import urllib.parse
import io

__all__ = ['parse_data_url','DataHandler']

def parse_data_url(url):
	scheme, data = url.split(":",1)
	assert scheme == "data", "unsupported scheme: "+scheme
	mediatype, data = data.split(",",1)
	# base64 urls might have a padding which might (should) be quoted:
	data = urllib.parse.unquote_to_bytes(data)
	if mediatype.endswith(";base64"):
		return binascii.a2b_base64(data), mediatype[:-7] or None
	else:
		return data, mediatype or None

class DataHandler(urllib.request.BaseHandler):
	def data_open(self, req):
		return io.BytesIO(parse_data_url(req.full_url)[0])

get_data_url_bin.py

#!/usr/bin/env python3
import sys
from dataurl import DataHandler
from urllib.request import urlopen, build_opener, install_opener

install_opener(build_opener(DataHandler))

# so we can write binary data to stdout:
sys.stdout = open(sys.stdout.fileno(),"wb")

for url in sys.argv[1:]:
	with urlopen(url) as f:
		sys.stdout.write(f.read())

get_data_url_text.py

#!/usr/bin/env python3
import sys
from dataurl import DataHandler
from urllib.request import urlopen, build_opener, install_opener

install_opener(build_opener(DataHandler))

for url in sys.argv[1:]:
	with urlopen(url) as f:
		# assumes utf-8 encoded text when no charset given:
		sys.stdout.write(f.read().decode(dict(f.headers.get_params() or []).get('charset','UTF-8')))