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Diffstat (limited to 'Lib/email/quopriMIME.py')
| -rw-r--r-- | Lib/email/quopriMIME.py | 312 |
1 files changed, 312 insertions, 0 deletions
diff --git a/Lib/email/quopriMIME.py b/Lib/email/quopriMIME.py new file mode 100644 index 0000000..002034e --- /dev/null +++ b/Lib/email/quopriMIME.py @@ -0,0 +1,312 @@ +# 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]') + + + +# Helpers +def header_quopri_check(c): + """Return true if the character should be escaped with header quopri.""" + return hqre.match(c) and 1 + + +def body_quopri_check(c): + """Return true if the character should be escaped with body quopri.""" + return bqre.match(c) and 1 + + +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) + elif len(L[-1]) + len(s) < maxlen: + L[-1] += extra + s + else: + L.append(s) + + +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=0, 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 set to 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=0, 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 encoded[-1] <> eol and decoded[-1] == 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) |