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Template tag for importing content from external url

Author:
dchandek
Posted:
April 23, 2008
Language:
Python
Version:
.96
Score:
1 (after 1 ratings)

Usage:

Literal value, use default timeout {% geturl "http://example.com/path/to/content/" %}

Variable value, literal timeout {% geturl object.urlfield 5 %} 

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@register.simple_tag
def geturl(url, timeout=None):
    """
    Usage: {% geturl url [timeout] %}

    Examples:
    {% geturl "http://example.com/path/to/content/" %}
    {% geturl object.urlfield 1 %} 
    """
    import socket
    from urllib2 import urlopen
    socket_default_timeout = socket.getdefaulttimeout()
    if timeout is not None:
        try:
            socket_timeout = float(timeout)
        except ValueError:
            raise template.TemplateSyntaxError, "timeout argument of geturl tag, if provided, must be convertible to a float"
        try:
            socket.setdefaulttimeout(socket_timeout)
        except ValueError:
            raise template.TemplateSyntaxError, "timeout argument of geturl tag, if provided, cannot be less than zero"
    try:
        try: 
            content = urlopen(url).read()
        finally: # reset socket timeout
            if timeout is not None:
                socket.setdefaulttimeout(socket_default_timeout) 
    except:
        content = ''        
    return content

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Comments

kioopi (on April 24, 2008):

This screams xss-vulnerability. Do you have control over the urls you include?

#

dchandek (on April 24, 2008):

The intention is similar to the <c:import/> tag of the JavaServer Pages Standard Tag Library (JSTL). It's up to the developer to use trusted sources. :)

#

dchandek (on April 24, 2008):

Updated to use template.Variable class from Django dev version. Also switched to urllib2 b/c urllib2.urlopen raises urllib2.HTTPError on 404, whereas urllib.urlopen simply returns 404 page content (bad).

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dchandek (on April 24, 2008):

Updated to use the simple_tag shortcut. :)

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cmheisel (on April 24, 2008):

If you use this in production there are a few things to be wary of (we've done something similar for trusted URLs at my job).

  • You'll want to set a timetout so slow servers don't hold up your page
  • You'll want some (serious) caching

From what I can tell, the way to set a timeout is: import socket; socket.setdefaulttimeout(seconds)

#

dchandek (on April 24, 2008):

Good point on the timeout issue. Caching, of course, can be handled using the {% cache %} template tag.

#

dchandek (on April 24, 2008):

Updated to deal with timeout issue. I have a minimal understanding of sockets and threads, so I played it safe by getting current default socket timeout at the outset and resetting the default at the end.

#

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