Permalink
Find file
Fetching contributors…
Cannot retrieve contributors at this time
executable file 152 lines (128 sloc) 5.3 KB
#!/usr/bin/env python
# Decode From and Subject lines spammers encode in other charsets
# to try to hide them from spam filters. (RFC 2047 encoding.)
# Use in conjunction with programs like procmail or spamassassin,
# instead of something like formail
import sys, os
import email
import email.utils
Debug = False
progname = os.path.basename(sys.argv[0])
Usage = """Usage: %s [-a] headername [filename]
Find a line matching the given header name (Subject:, From:, etc.)
and decode it according to RFC 2047.
Without a filemame, will read standard input.
Adding -a will print all matches within the given file, not just the first.
Multiple headers may be combined with |
Example: %s -a Subject: /var/mail/yourname
%s -a 'Subject:|To:|From:' folder folder""" % (progname, progname,
progname)
def decode_piece(piece):
ret = ''
for part in email.Header.decode_header(piece):
ret += part[0]
# Special case: the header itself comes out with charset None
# and decode doesn't add a space between it and the next part,
# even though there was a space in the original. So add one.
# I'm taking a wild guess that the relevant factor here is
# the None charset rather than the fact that it matched
# the header, but keep an eye open for counterexamples.
if not part[1]:
ret += ' '
return ret
def decode_file(filename, header_wanted, all=False):
if filename == '-':
fil = sys.stdin
else:
fil = open(filename)
# header_wanted can be multiple headers, e.g. From:|To:
# so split them.
headers = header_wanted.split('|')
output = ''
found_something = False
for line in fil:
# if Debug:
# print "line:", line
# If it matches the header we seek, or if we've already started
# matching the header and we're looking for continuation lines,
# build up our string:
for header_wanted in headers:
# if Debug:
# print "=== looking for", header_wanted
if (not output and line.startswith(header_wanted)) \
or (output and (line.startswith(' ') or line.startswith('\t'))):
# We have a match! But we may need to read multiple lines,
# since one header can be split over several lines.
found_something = True
if Debug:
print "\nFound something:", line
print " which decodes to:", decode_piece(line.strip())
# Strip output because we don't want the final newline.
# But add a space if this is a continuation.
if output:
output += ' '
thispiece = decode_piece(line.strip())
if Debug:
print "decode_piece returned: '%s'" % thispiece
# If the header is an address, we have to split it into parts
# before we can decode it. If it's another header
# such as Subject, we can't do that.
if header_wanted.startswith("From") \
or header_wanted.startswith("To") \
or header_wanted.startswith("Cc") \
or header_wanted.startswith("Bcc"):
pieces = email.utils.parseaddr(thispiece)
if pieces[0] or pieces[1]:
if Debug:
print "formataddr says: '%s'" % \
email.utils.formataddr(map(decode_piece, pieces)).strip()
output += header_wanted + ' ' + \
email.utils.formataddr(map(decode_piece,
pieces)).strip()
else:
output += thispiece
print "parseaddr failed on", thispiece,
else:
output += thispiece
if Debug:
print "Now output is ---%s---" % output
elif output:
# if we've already matched the header, and this isn't a
# continuation line, then we're done. Print and exit.
if Debug:
print "output:", output
print "stripped output:",
print output.strip()
if all:
output = ''
else:
sys.exit(0)
if output:
if Debug:
print "final output:",
print output.strip()
# If we get here, we never matched a header,
# or ended with a continuation line.
if not found_something:
print "No such header", header_wanted, "in", filename
return
if sys.argv[1] == '-h' or sys.argv[1] == '--help':
print Usage
sys.exit(1)
# A -a argument means don't stop at the first header,
# decode all matching headers in the file.
if sys.argv[1] == '-a':
all = True
sys.argv = sys.argv[1:]
else:
all = False
header_wanted = sys.argv[1]
try:
if len(sys.argv) > 2:
for filename in sys.argv[2:]:
decode_file(filename, header_wanted, all)
else:
fil = sys.stdin
decode_file('-', header_wanted)
except KeyboardInterrupt:
sys.exit(1)