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# Copyright (C) 2004 Mike Wray <mike.wray@hp.com>
"""Encoding for arguments to HTTP calls.
Uses the url-encoding with MIME type 'application/x-www-form-urlencoded'
if the data does not include files. Otherwise it uses the encoding with
MIME type 'multipart/form-data'. See the HTML4 spec for details.
"""
import sys
import types
from StringIO import StringIO
import urllib
import httplib
import random
import md5
# Extract from HTML4 spec.
## The following example illustrates "multipart/form-data"
## encoding. Suppose we have the following form:
## <FORM action="http://server.com/cgi/handle"
## enctype="multipart/form-data"
## method="post">
## <P>
## What is your name? <INPUT type="text" name="submit-name"><BR>
## What files are you sending? <INPUT type="file" name="files"><BR>
## <INPUT type="submit" value="Send"> <INPUT type="reset">
## </FORM>
## If the user enters "Larry" in the text input, and selects the text
## file "file1.txt", the user agent might send back the following data:
## Content-Type: multipart/form-data; boundary=AaB03x
## --AaB03x
## Content-Disposition: form-data; name="submit-name"
## Larry
## --AaB03x
## Content-Disposition: form-data; name="files"; filename="file1.txt"
## Content-Type: text/plain
## ... contents of file1.txt ...
## --AaB03x--
## If the user selected a second (image) file "file2.gif", the user agent
## might construct the parts as follows:
## Content-Type: multipart/form-data; boundary=AaB03x
## --AaB03x
## Content-Disposition: form-data; name="submit-name"
## Larry
## --AaB03x
## Content-Disposition: form-data; name="files"
## Content-Type: multipart/mixed; boundary=BbC04y
## --BbC04y
## Content-Disposition: file; filename="file1.txt"
## Content-Type: text/plain
## ... contents of file1.txt ...
## --BbC04y
## Content-Disposition: file; filename="file2.gif"
## Content-Type: image/gif
## Content-Transfer-Encoding: binary
## ...contents of file2.gif...
## --BbC04y--
## --AaB03x--
__all__ = ['encode_data', 'encode_multipart', 'encode_form', 'mime_boundary' ]
def data_values(d):
if isinstance(d, types.DictType):
return d.items()
else:
return d
def encode_data(d):
"""Encode some data for HTTP transport.
The encoding used is stored in 'Content-Type' in the headers.
d data - sequence of tuples or dictionary
returns a 2-tuple of the headers and the encoded data
"""
val = ({}, None)
if d is None: return val
multipart = 0
for (k, v) in data_values(d):
if encode_isfile(v):
multipart = 1
break
if multipart:
val = encode_multipart(d)
else:
val = encode_form(d)
return val
def encode_isfile(v):
if isinstance(v, types.FileType):
return 1
if hasattr(v, 'readlines'):
return 1
return 0
def encode_multipart(d):
boundary = mime_boundary()
hdr = { 'Content-Type': 'multipart/form-data; boundary=' + boundary }
out = StringIO()
for (k,v) in data_values(d):
out.write('--')
out.write(boundary)
out.write('\r\n')
if encode_isfile(v):
out.write('Content-Disposition: form-data; name="')
out.write(k)
if hasattr(v, 'name'):
out.write('"; filename="')
out.write(v.name)
out.write('"\r\n')
out.write('Content-Type: application/octet-stream\r\n')
out.write('\r\n')
for l in v.readlines():
out.write(l)
else:
out.write('Content-Disposition: form-data; name="')
out.write(k)
out.write('"\r\n')
out.write('\r\n')
out.write(str(v))
out.write('\r\n')
out.write('--')
out.write(boundary)
out.write('--')
out.write('\r\n')
return (hdr, out.getvalue())
def mime_boundary():
random.seed()
m = md5.new()
for i in range(0, 10):
c = chr(random.randint(1, 255))
m.update(c)
b = m.hexdigest()
return b[0:16]
def encode_form(d):
hdr = { 'Content-Type': 'application/x-www-form-urlencoded' }
val = urllib.urlencode(d)
return (hdr, val)
def main():
#d = {'a': 1, 'b': 'x y', 'c': file('conf.sxp') }
#d = {'a': 1, 'b': 'x y' }
d = [ ('a', 1), ('b', 'x y'), ('c', file('conf.sxp')) ]
#d = [ ('a', 1), ('b', 'x y')]
v = encode_data(d)
print v[0]
sys.stdout.write(v[1])
print
if __name__ == "__main__":
main()
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