POST from a CGI

Wed Sep 22 18:25:36 EDT 2004

Sorry to top post... but it looks like my problem may be with the
latest version of ClientCookie rather than with the principles of what
I'm doing...

Fuzzy

fuzzyman at gmail.com (Michael Foord) wrote in message news:<6f402501.0409220027.65be4885 at posting.google.com>...
> I'm receiving POST data to a CGI, which I'd like to forward to another
> CGI using urllib2.
> 
> I have two options -
> 
> 1) Parse the data using cgi.FieldStorage() and then rebuild the POST
> request into a dictionary - including any files (? uploading files by
> urllib2 untested and undocumented - examples seem to be for httplib).
> 
> 2) Read the whole POST data in using sys.stdin.read(), rebuild the
> 'Content-type' and 'Content-length' headers and make the POST.
> 
> Obviously (2) is a *lot* less fiddly and less error prone. *But* I'm
> getting 400 errors when I try it (server thinks request is malformed).
> I've checked the headers and the body data and they seem normal and I
> can't work it out.
> 
> I wonder if anyone can see what I'm doing wrong......
> (Simple code shown first - then a straightforward example that ought
> to work and fails).
> 
> MAXUPLOAD  = 10000                                              # set
> max file size of 10 000 bytes
> txdata = None
> if os.environ.get('REQUEST_METHOD','').lower()=='post':         # read
> in the POST data from stdin
>     txdata = sys.stdin.read(MAXUPLOAD)
>     if len(txdata)==MAXUPLOAD and sys.stdin.read(1):
>         print overmax 
>         sys.exit(1)                                             #
> print an error message if too big a file is uploaded
> 
> 
> envdict = { 'HTTP_CACHE_CONTROL' : 'Cache-control', 'CONTENT_TYPE' :
> 'Content-type',
>             'HTTP_ACCEPT_LANGUAGE' : 'Accept-language', 'HTTP_ACCEPT'
> : 'Accept',
>             'HTTP_PRAGMA' : 'Pragma', 'HTTP_CONNECTION' :
> 'Connection',
>             }                                                   #
> these are request headers from the browser to the CGI
>                                                                 # that
> we're going to rebuild from the environment variables
> defaultuseragent =  'Mozilla/4.0 (compatible; MSIE 5.5; Windows NT)'  
>         # default User-agent
> txheaders = {}
> for envvar, header in envdict.items():                  # go through
> the environment variables putting any headers back
>     testval = os.environ.get(envvar)
>     if testval:
>         txheaders[header] = testval
> txheaders['User-agent'] = os.environ.get('HTTP_USER_AGENT',
> defaultuseragent)   # put in a default user agent if we haven't got
> one
> if txdata and txheaders.has_key('Content-type'):
> txheaders['Content-length'] = str(len(txdata))     # we only need a
> 'Content-length' header if we have a 'Content-type' one...
> 
> theurl = 'http://www.someserver.com/somepath/somepage.html'         #
> In actual fact I normally decode the url from the PATH_INFO
> 
> req = urllib2.Request(theurl, txdata, txheaders)         # create the
> request object
> try:
>     u = urllib2.urlopen(req)        # fetch a handle on the url !
> except IOError, e:
>     if not hasattr(e,'code'):
>         thecode = 0
>     else:
>         thecode = e.code
>     print 'Content-type: text/html'
>     print '<HTML><BODY><H1>Error Code %s</H1></BODY></HTML>' % e.code
> 
> info = u.info()         # info about the url
> pagetype = info.gettype()
> print 'Content-type: ' + pagetype + '\n'
> print u.read()          # print the received page
> 
> ###############################################################
> 
> In the code I actually use I make a logfile as well which logs txdata,
> txheaders and all the environment variables.
> 
> Making a simple post to  my guestbook (
> http://www.voidspace.xennos.com/cgi-bin/guestbook.py ) using this
> method I get a 400 error.
> From the log I can see the following headers :
> (printed using headername, '  :  ', value)
> 
> Connection    :    keep-alive
> Accept-language    :    en-gb
> Pragma    :    no-cache
> Cache-control    :    max-age=259200
> Content-type    :    application/x-www-form-urlencoded
> Content-length    :    62
> Accept    :    image/gif, image/x-xbitmap, image/jpeg, image/pjpeg,
> application/x-shockwave-flash, application/msword, */*
> User-agent    :    Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1)
> 
> 
> And the following POST data :
> name=Fuzzyman&email=&homepage=&location=&comment=CGI+post+test
> 
> Which even has a length of 62.... The only thing I can think of is
> that the headers are appearing in the wrong order ?
> Can anyone else see what I'm doing wrong ?
> 
> Regards,
> 
> 
> Fuzzy
> http://www.voidspace.org.uk/atlantibots/pythonutils.html