mirror of
https://github.com/python/cpython.git
synced 2024-11-24 18:34:43 +08:00
319 lines
10 KiB
Python
319 lines
10 KiB
Python
# Copyright (C) 2001,2002 Python Software Foundation
|
||
# Author: che@debian.org (Ben Gertzfield)
|
||
|
||
"""Quoted-printable content transfer encoding per RFCs 2045-2047.
|
||
|
||
This module handles the content transfer encoding method defined in RFC 2045
|
||
to encode US ASCII-like 8-bit data called `quoted-printable'. It is used to
|
||
safely encode text that is in a character set similar to the 7-bit US ASCII
|
||
character set, but that includes some 8-bit characters that are normally not
|
||
allowed in email bodies or headers.
|
||
|
||
Quoted-printable is very space-inefficient for encoding binary files; use the
|
||
email.base64MIME module for that instead.
|
||
|
||
This module provides an interface to encode and decode both headers and bodies
|
||
with quoted-printable encoding.
|
||
|
||
RFC 2045 defines a method for including character set information in an
|
||
`encoded-word' in a header. This method is commonly used for 8-bit real names
|
||
in To:/From:/Cc: etc. fields, as well as Subject: lines.
|
||
|
||
This module does not do the line wrapping or end-of-line character
|
||
conversion necessary for proper internationalized headers; it only
|
||
does dumb encoding and decoding. To deal with the various line
|
||
wrapping issues, use the email.Header module.
|
||
"""
|
||
|
||
import re
|
||
from string import hexdigits
|
||
from email.Utils import fix_eols
|
||
|
||
CRLF = '\r\n'
|
||
NL = '\n'
|
||
|
||
# See also Charset.py
|
||
MISC_LEN = 7
|
||
|
||
hqre = re.compile(r'[^-a-zA-Z0-9!*+/ ]')
|
||
bqre = re.compile(r'[^ !-<>-~\t]')
|
||
|
||
try:
|
||
True, False
|
||
except NameError:
|
||
True = 1
|
||
False = 0
|
||
|
||
|
||
|
||
# Helpers
|
||
def header_quopri_check(c):
|
||
"""Return True if the character should be escaped with header quopri."""
|
||
return hqre.match(c) and True
|
||
|
||
|
||
def body_quopri_check(c):
|
||
"""Return True if the character should be escaped with body quopri."""
|
||
return bqre.match(c) and True
|
||
|
||
|
||
def header_quopri_len(s):
|
||
"""Return the length of str when it is encoded with header quopri."""
|
||
count = 0
|
||
for c in s:
|
||
if hqre.match(c):
|
||
count += 3
|
||
else:
|
||
count += 1
|
||
return count
|
||
|
||
|
||
def body_quopri_len(str):
|
||
"""Return the length of str when it is encoded with body quopri."""
|
||
count = 0
|
||
for c in str:
|
||
if bqre.match(c):
|
||
count += 3
|
||
else:
|
||
count += 1
|
||
return count
|
||
|
||
|
||
def _max_append(L, s, maxlen, extra=''):
|
||
if not L:
|
||
L.append(s.lstrip())
|
||
elif len(L[-1]) + len(s) < maxlen:
|
||
L[-1] += extra + s
|
||
else:
|
||
L.append(s.lstrip())
|
||
|
||
|
||
def unquote(s):
|
||
"""Turn a string in the form =AB to the ASCII character with value 0xab"""
|
||
return chr(int(s[1:3], 16))
|
||
|
||
|
||
def quote(c):
|
||
return "=%02X" % ord(c)
|
||
|
||
|
||
|
||
def header_encode(header, charset="iso-8859-1", keep_eols=False,
|
||
maxlinelen=76, eol=NL):
|
||
"""Encode a single header line with quoted-printable (like) encoding.
|
||
|
||
Defined in RFC 2045, this `Q' encoding is similar to quoted-printable, but
|
||
used specifically for email header fields to allow charsets with mostly 7
|
||
bit characters (and some 8 bit) to remain more or less readable in non-RFC
|
||
2045 aware mail clients.
|
||
|
||
charset names the character set to use to encode the header. It defaults
|
||
to iso-8859-1.
|
||
|
||
The resulting string will be in the form:
|
||
|
||
"=?charset?q?I_f=E2rt_in_your_g=E8n=E8ral_dire=E7tion?\\n
|
||
=?charset?q?Silly_=C8nglish_Kn=EEghts?="
|
||
|
||
with each line wrapped safely at, at most, maxlinelen characters (defaults
|
||
to 76 characters).
|
||
|
||
End-of-line characters (\\r, \\n, \\r\\n) will be automatically converted
|
||
to the canonical email line separator \\r\\n unless the keep_eols
|
||
parameter is True (the default is False).
|
||
|
||
Each line of the header will be terminated in the value of eol, which
|
||
defaults to "\\n". Set this to "\\r\\n" if you are using the result of
|
||
this function directly in email.
|
||
"""
|
||
# Return empty headers unchanged
|
||
if not header:
|
||
return header
|
||
|
||
if not keep_eols:
|
||
header = fix_eols(header)
|
||
|
||
# Quopri encode each line, in encoded chunks no greater than maxlinelen in
|
||
# lenght, after the RFC chrome is added in.
|
||
quoted = []
|
||
max_encoded = maxlinelen - len(charset) - MISC_LEN
|
||
|
||
for c in header:
|
||
# Space may be represented as _ instead of =20 for readability
|
||
if c == ' ':
|
||
_max_append(quoted, '_', max_encoded)
|
||
# These characters can be included verbatim
|
||
elif not hqre.match(c):
|
||
_max_append(quoted, c, max_encoded)
|
||
# Otherwise, replace with hex value like =E2
|
||
else:
|
||
_max_append(quoted, "=%02X" % ord(c), max_encoded)
|
||
|
||
# Now add the RFC chrome to each encoded chunk and glue the chunks
|
||
# together. BAW: should we be able to specify the leading whitespace in
|
||
# the joiner?
|
||
joiner = eol + ' '
|
||
return joiner.join(['=?%s?q?%s?=' % (charset, line) for line in quoted])
|
||
|
||
|
||
|
||
def encode(body, binary=False, maxlinelen=76, eol=NL):
|
||
"""Encode with quoted-printable, wrapping at maxlinelen characters.
|
||
|
||
If binary is False (the default), end-of-line characters will be converted
|
||
to the canonical email end-of-line sequence \\r\\n. Otherwise they will
|
||
be left verbatim.
|
||
|
||
Each line of encoded text will end with eol, which defaults to "\\n". Set
|
||
this to "\\r\\n" if you will be using the result of this function directly
|
||
in an email.
|
||
|
||
Each line will be wrapped at, at most, maxlinelen characters (defaults to
|
||
76 characters). Long lines will have the `soft linefeed' quoted-printable
|
||
character "=" appended to them, so the decoded text will be identical to
|
||
the original text.
|
||
"""
|
||
if not body:
|
||
return body
|
||
|
||
if not binary:
|
||
body = fix_eols(body)
|
||
|
||
# BAW: We're accumulating the body text by string concatenation. That
|
||
# can't be very efficient, but I don't have time now to rewrite it. It
|
||
# just feels like this algorithm could be more efficient.
|
||
encoded_body = ''
|
||
lineno = -1
|
||
# Preserve line endings here so we can check later to see an eol needs to
|
||
# be added to the output later.
|
||
lines = body.splitlines(1)
|
||
for line in lines:
|
||
# But strip off line-endings for processing this line.
|
||
if line.endswith(CRLF):
|
||
line = line[:-2]
|
||
elif line[-1] in CRLF:
|
||
line = line[:-1]
|
||
|
||
lineno += 1
|
||
encoded_line = ''
|
||
prev = None
|
||
linelen = len(line)
|
||
# Now we need to examine every character to see if it needs to be
|
||
# quopri encoded. BAW: again, string concatenation is inefficient.
|
||
for j in range(linelen):
|
||
c = line[j]
|
||
prev = c
|
||
if bqre.match(c):
|
||
c = quote(c)
|
||
elif j+1 == linelen:
|
||
# Check for whitespace at end of line; special case
|
||
if c not in ' \t':
|
||
encoded_line += c
|
||
prev = c
|
||
continue
|
||
# Check to see to see if the line has reached its maximum length
|
||
if len(encoded_line) + len(c) >= maxlinelen:
|
||
encoded_body += encoded_line + '=' + eol
|
||
encoded_line = ''
|
||
encoded_line += c
|
||
# Now at end of line..
|
||
if prev and prev in ' \t':
|
||
# Special case for whitespace at end of file
|
||
if lineno + 1 == len(lines):
|
||
prev = quote(prev)
|
||
if len(encoded_line) + len(prev) > maxlinelen:
|
||
encoded_body += encoded_line + '=' + eol + prev
|
||
else:
|
||
encoded_body += encoded_line + prev
|
||
# Just normal whitespace at end of line
|
||
else:
|
||
encoded_body += encoded_line + prev + '=' + eol
|
||
encoded_line = ''
|
||
# Now look at the line we just finished and it has a line ending, we
|
||
# need to add eol to the end of the line.
|
||
if lines[lineno].endswith(CRLF) or lines[lineno][-1] in CRLF:
|
||
encoded_body += encoded_line + eol
|
||
else:
|
||
encoded_body += encoded_line
|
||
encoded_line = ''
|
||
return encoded_body
|
||
|
||
|
||
# For convenience and backwards compatibility w/ standard base64 module
|
||
body_encode = encode
|
||
encodestring = encode
|
||
|
||
|
||
|
||
# BAW: I'm not sure if the intent was for the signature of this function to be
|
||
# the same as base64MIME.decode() or not...
|
||
def decode(encoded, eol=NL):
|
||
"""Decode a quoted-printable string.
|
||
|
||
Lines are separated with eol, which defaults to \\n.
|
||
"""
|
||
if not encoded:
|
||
return encoded
|
||
# BAW: see comment in encode() above. Again, we're building up the
|
||
# decoded string with string concatenation, which could be done much more
|
||
# efficiently.
|
||
decoded = ''
|
||
|
||
for line in encoded.splitlines():
|
||
line = line.rstrip()
|
||
if not line:
|
||
decoded += eol
|
||
continue
|
||
|
||
i = 0
|
||
n = len(line)
|
||
while i < n:
|
||
c = line[i]
|
||
if c <> '=':
|
||
decoded += c
|
||
i += 1
|
||
# Otherwise, c == "=". Are we at the end of the line? If so, add
|
||
# a soft line break.
|
||
elif i+1 == n:
|
||
i += 1
|
||
continue
|
||
# Decode if in form =AB
|
||
elif i+2 < n and line[i+1] in hexdigits and line[i+2] in hexdigits:
|
||
decoded += unquote(line[i:i+3])
|
||
i += 3
|
||
# Otherwise, not in form =AB, pass literally
|
||
else:
|
||
decoded += c
|
||
i += 1
|
||
|
||
if i == n:
|
||
decoded += eol
|
||
# Special case if original string did not end with eol
|
||
if not encoded.endswith(eol) and decoded.endswith(eol):
|
||
decoded = decoded[:-1]
|
||
return decoded
|
||
|
||
|
||
# For convenience and backwards compatibility w/ standard base64 module
|
||
body_decode = decode
|
||
decodestring = decode
|
||
|
||
|
||
|
||
def _unquote_match(match):
|
||
"""Turn a match in the form =AB to the ASCII character with value 0xab"""
|
||
s = match.group(0)
|
||
return unquote(s)
|
||
|
||
|
||
# Header decoding is done a bit differently
|
||
def header_decode(s):
|
||
"""Decode a string encoded with RFC 2045 MIME header `Q' encoding.
|
||
|
||
This function does not parse a full MIME header value encoded with
|
||
quoted-printable (like =?iso-8895-1?q?Hello_World?=) -- please use
|
||
the high level email.Header class for that functionality.
|
||
"""
|
||
s = s.replace('_', ' ')
|
||
return re.sub(r'=\w{2}', _unquote_match, s)
|