"""Utility functions for HTTP header value parsing and construction.
Copyright 1997-1998, Gisle Aas
Copyright 2002-2006, John J. Lee
This code is free software; you can redistribute it and/or modify it
under the terms of the BSD or ZPL 2.1 licenses (see the file
COPYING.txt included with the distribution).
"""
import os, re
from types import StringType
from types import UnicodeType
STRING_TYPES = StringType, UnicodeType
from _util import http2time
import _rfc3986
def is_html_file_extension(url, allow_xhtml):
ext = os.path.splitext(_rfc3986.urlsplit(url)[2])[1]
html_exts = [".htm", ".html"]
if allow_xhtml:
html_exts += [".xhtml"]
return ext in html_exts
def is_html(ct_headers, url, allow_xhtml=False):
"""
ct_headers: Sequence of Content-Type headers
url: Response URL
"""
if not ct_headers:
return is_html_file_extension(url, allow_xhtml)
headers = split_header_words(ct_headers)
if len(headers) < 1:
return is_html_file_extension(url, allow_xhtml)
first_header = headers[0]
first_parameter = first_header[0]
ct = first_parameter[0]
html_types = ["text/html"]
if allow_xhtml:
html_types += [
"text/xhtml", "text/xml",
"application/xml", "application/xhtml+xml",
]
return ct in html_types
def unmatched(match):
"""Return unmatched part of re.Match object."""
start, end = match.span(0)
return match.string[:start]+match.string[end:]
token_re = re.compile(r"^\s*([^=\s;,]+)")
quoted_value_re = re.compile(r"^\s*=\s*\"([^\"\\]*(?:\\.[^\"\\]*)*)\"")
value_re = re.compile(r"^\s*=\s*([^\s;,]*)")
escape_re = re.compile(r"\\(.)")
def split_header_words(header_values):
r"""Parse header values into a list of lists containing key,value pairs.
The function knows how to deal with ",", ";" and "=" as well as quoted
values after "=". A list of space separated tokens are parsed as if they
were separated by ";".
If the header_values passed as argument contains multiple values, then they
are treated as if they were a single value separated by comma ",".
This means that this function is useful for parsing header fields that
follow this syntax (BNF as from the HTTP/1.1 specification, but we relax
the requirement for tokens).
headers = #header
header = (token | parameter) *( [";"] (token | parameter))
token = 1*<any CHAR except CTLs or separators>
separators = "(" | ")" | "<" | ">" | "@"
| "," | ";" | ":" | "\" | <">
| "/" | "[" | "]" | "?" | "="
| "{" | "}" | SP | HT
quoted-string = ( <"> *(qdtext | quoted-pair ) <"> )
qdtext = <any TEXT except <">>
quoted-pair = "\" CHAR
parameter = attribute "=" value
attribute = token
value = token | quoted-string
Each header is represented by a list of key/value pairs. The value for a
simple token (not part of a parameter) is None. Syntactically incorrect
headers will not necessarily be parsed as you would want.
This is easier to describe with some examples:
>>> split_header_words(['foo="bar"; port="80,81"; discard, bar=baz'])
[[('foo', 'bar'), ('port', '80,81'), ('discard', None)], [('bar', 'baz')]]
>>> split_header_words(['text/html; charset="iso-8859-1"'])
[[('text/html', None), ('charset', 'iso-8859-1')]]
>>> split_header_words([r'Basic realm="\"foo\bar\""'])
[[('Basic', None), ('realm', '"foobar"')]]
"""
assert type(header_values) not in STRING_TYPES
result = []
for text in header_values:
orig_text = text
pairs = []
while text:
m = token_re.search(text)
if m:
text = unmatched(m)
name = m.group(1)
m = quoted_value_re.search(text)
if m: # quoted value
text = unmatched(m)
value = m.group(1)
value = escape_re.sub(r"\1", value)
else:
m = value_re.search(text)
if m: # unquoted value
text = unmatched(m)
value = m.group(1)
value = value.rstrip()
else:
# no value, a lone token
value = None
pairs.append((name, value))
elif text.lstrip().startswith(","):
# concatenated headers, as per RFC 2616 section 4.2
text = text.lstrip()[1:]
if pairs: result.append(pairs)
pairs = []
else:
# skip junk
non_junk, nr_junk_chars = re.subn("^[=\s;]*", "", text)
assert nr_junk_chars > 0, (
"split_header_words bug: '%s', '%s', %s" %
(orig_text, text, pairs))
text = non_junk
if pairs: result.append(pairs)
return result
join_escape_re = re.compile(r"([\"\\])")
def join_header_words(lists):
"""Do the inverse of the conversion done by split_header_words.
Takes a list of lists of (key, value) pairs and produces a single header
value. Attribute values are quoted if needed.
>>> join_header_words([[("text/plain", None), ("charset", "iso-8859/1")]])
'text/plain; charset="iso-8859/1"'
>>> join_header_words([[("text/plain", None)], [("charset", "iso-8859/1")]])
'text/plain, charset="iso-8859/1"'
"""
headers = []
for pairs in lists:
attr = []
for k, v in pairs:
if v is not None:
if not re.search(r"^\w+$", v):
v = join_escape_re.sub(r"\\\1", v) # escape " and \
v = '"%s"' % v
if k is None: # Netscape cookies may have no name
k = v
else:
k = "%s=%s" % (k, v)
attr.append(k)
if attr: headers.append("; ".join(attr))
return ", ".join(headers)
def strip_quotes(text):
if text.startswith('"'):
text = text[1:]
if text.endswith('"'):
text = text[:-1]
return text
def parse_ns_headers(ns_headers):
"""Ad-hoc parser for Netscape protocol cookie-attributes.
The old Netscape cookie format for Set-Cookie can for instance contain
an unquoted "," in the expires field, so we have to use this ad-hoc
parser instead of split_header_words.
XXX This may not make the best possible effort to parse all the crap
that Netscape Cookie headers contain. Ronald Tschalar's HTTPClient
parser is probably better, so could do worse than following that if
this ever gives any trouble.
Currently, this is also used for parsing RFC 2109 cookies.
"""
known_attrs = ("expires", "domain", "path", "secure",
# RFC 2109 attrs (may turn up in Netscape cookies, too)
"version", "port", "max-age")
result = []
for ns_header in ns_headers:
pairs = []
version_set = False
params = re.split(r";\s*", ns_header)
for ii in range(len(params)):
param = params[ii]
param = param.rstrip()
if param == "": continue
if "=" not in param:
k, v = param, None
else:
k, v = re.split(r"\s*=\s*", param, 1)
k = k.lstrip()
if ii != 0:
lc = k.lower()
if lc in known_attrs:
k = lc
if k == "version":
# This is an RFC 2109 cookie.
v = strip_quotes(v)
version_set = True
if k == "expires":
# convert expires date to seconds since epoch
v = http2time(strip_quotes(v)) # None if invalid
pairs.append((k, v))
if pairs:
if not version_set:
pairs.append(("version", "0"))
result.append(pairs)
return result
def _test():
import doctest, _headersutil
return doctest.testmod(_headersutil)
if __name__ == "__main__":
_test()
