From b38e5e2252831c219d83f2c71ece359ece23fdbd Mon Sep 17 00:00:00 2001
From: Jeremy Fincher <jemfinch@users.sourceforge.net>
Date: Tue, 25 Mar 2003 23:24:38 +0000
Subject: [PATCH] Initial import; workaround for bug in Python 2.2 rfc822.py

---
 others/rfc822.py | 1013 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 1013 insertions(+)
 create mode 100755 others/rfc822.py

diff --git a/others/rfc822.py b/others/rfc822.py
new file mode 100755
index 000000000..3c74111ad
--- /dev/null
+++ b/others/rfc822.py
@@ -0,0 +1,1013 @@
+"""RFC 2822 message manipulation.
+
+Note: This is only a very rough sketch of a full RFC-822 parser; in particular
+the tokenizing of addresses does not adhere to all the quoting rules.
+
+Note: RFC 2822 is a long awaited update to RFC 822.  This module should
+conform to RFC 2822, and is thus mis-named (it's not worth renaming it).  Some
+effort at RFC 2822 updates have been made, but a thorough audit has not been
+performed.  Consider any RFC 2822 non-conformance to be a bug.
+
+    RFC 2822: http://www.faqs.org/rfcs/rfc2822.html
+    RFC 822 : http://www.faqs.org/rfcs/rfc822.html (obsolete)
+
+Directions for use:
+
+To create a Message object: first open a file, e.g.:
+
+  fp = open(file, 'r')
+
+You can use any other legal way of getting an open file object, e.g. use
+sys.stdin or call os.popen().  Then pass the open file object to the Message()
+constructor:
+
+  m = Message(fp)
+
+This class can work with any input object that supports a readline method.  If
+the input object has seek and tell capability, the rewindbody method will
+work; also illegal lines will be pushed back onto the input stream.  If the
+input object lacks seek but has an `unread' method that can push back a line
+of input, Message will use that to push back illegal lines.  Thus this class
+can be used to parse messages coming from a buffered stream.
+
+The optional `seekable' argument is provided as a workaround for certain stdio
+libraries in which tell() discards buffered data before discovering that the
+lseek() system call doesn't work.  For maximum portability, you should set the
+seekable argument to zero to prevent that initial \code{tell} when passing in
+an unseekable object such as a a file object created from a socket object.  If
+it is 1 on entry -- which it is by default -- the tell() method of the open
+file object is called once; if this raises an exception, seekable is reset to
+0.  For other nonzero values of seekable, this test is not made.
+
+To get the text of a particular header there are several methods:
+
+  str = m.getheader(name)
+  str = m.getrawheader(name)
+
+where name is the name of the header, e.g. 'Subject'.  The difference is that
+getheader() strips the leading and trailing whitespace, while getrawheader()
+doesn't.  Both functions retain embedded whitespace (including newlines)
+exactly as they are specified in the header, and leave the case of the text
+unchanged.
+
+For addresses and address lists there are functions
+
+  realname, mailaddress = m.getaddr(name)
+  list = m.getaddrlist(name)
+
+where the latter returns a list of (realname, mailaddr) tuples.
+
+There is also a method
+
+  time = m.getdate(name)
+
+which parses a Date-like field and returns a time-compatible tuple,
+i.e. a tuple such as returned by time.localtime() or accepted by
+time.mktime().
+
+See the class definition for lower level access methods.
+
+There are also some utility functions here.
+"""
+# Cleanup and extensions by Eric S. Raymond <esr@thyrsus.com>
+
+import time
+
+__all__ = ["Message","AddressList","parsedate","parsedate_tz","mktime_tz"]
+
+_blanklines = ('\r\n', '\n')            # Optimization for islast()
+
+
+class Message:
+    """Represents a single RFC 2822-compliant message."""
+
+    def __init__(self, fp, seekable = 1):
+        """Initialize the class instance and read the headers."""
+        if seekable == 1:
+            # Exercise tell() to make sure it works
+            # (and then assume seek() works, too)
+            try:
+                fp.tell()
+            except (AttributeError, IOError):
+                seekable = 0
+            else:
+                seekable = 1
+        self.fp = fp
+        self.seekable = seekable
+        self.startofheaders = None
+        self.startofbody = None
+        #
+        if self.seekable:
+            try:
+                self.startofheaders = self.fp.tell()
+            except IOError:
+                self.seekable = 0
+        #
+        self.readheaders()
+        #
+        if self.seekable:
+            try:
+                self.startofbody = self.fp.tell()
+            except IOError:
+                self.seekable = 0
+
+    def rewindbody(self):
+        """Rewind the file to the start of the body (if seekable)."""
+        if not self.seekable:
+            raise IOError, "unseekable file"
+        self.fp.seek(self.startofbody)
+
+    def readheaders(self):
+        """Read header lines.
+
+        Read header lines up to the entirely blank line that terminates them.
+        The (normally blank) line that ends the headers is skipped, but not
+        included in the returned list.  If a non-header line ends the headers,
+        (which is an error), an attempt is made to backspace over it; it is
+        never included in the returned list.
+
+        The variable self.status is set to the empty string if all went well,
+        otherwise it is an error message.  The variable self.headers is a
+        completely uninterpreted list of lines contained in the header (so
+        printing them will reproduce the header exactly as it appears in the
+        file).
+        """
+        self.dict = {}
+        self.unixfrom = ''
+        self.headers = list = []
+        self.status = ''
+        headerseen = ""
+        firstline = 1
+        startofline = unread = tell = None
+        if hasattr(self.fp, 'unread'):
+            unread = self.fp.unread
+        elif self.seekable:
+            tell = self.fp.tell
+        while 1:
+            if tell:
+                try:
+                    startofline = tell()
+                except IOError:
+                    startofline = tell = None
+                    self.seekable = 0
+            line = self.fp.readline()
+            if not line:
+                self.status = 'EOF in headers'
+                break
+            # Skip unix From name time lines
+            if firstline and line.startswith('From '):
+                self.unixfrom = self.unixfrom + line
+                continue
+            firstline = 0
+            if headerseen and line[0] in ' \t':
+                # It's a continuation line.
+                list.append(line)
+                x = (self.dict[headerseen] + "\n " + line.strip())
+                self.dict[headerseen] = x.strip()
+                continue
+            elif self.iscomment(line):
+                # It's a comment.  Ignore it.
+                continue
+            elif self.islast(line):
+                # Note! No pushback here!  The delimiter line gets eaten.
+                break
+            headerseen = self.isheader(line)
+            if headerseen:
+                # It's a legal header line, save it.
+                list.append(line)
+                self.dict[headerseen] = line[len(headerseen)+1:].strip()
+                continue
+            else:
+                # It's not a header line; throw it back and stop here.
+                if not self.dict:
+                    self.status = 'No headers'
+                else:
+                    self.status = 'Non-header line where header expected'
+                # Try to undo the read.
+                if unread:
+                    unread(line)
+                elif tell:
+                    self.fp.seek(startofline)
+                else:
+                    self.status = self.status + '; bad seek'
+                break
+
+    def isheader(self, line):
+        """Determine whether a given line is a legal header.
+
+        This method should return the header name, suitably canonicalized.
+        You may override this method in order to use Message parsing on tagged
+        data in RFC 2822-like formats with special header formats.
+        """
+        i = line.find(':')
+        if i > 0:
+            return line[:i].lower()
+        else:
+            return None
+
+    def islast(self, line):
+        """Determine whether a line is a legal end of RFC 2822 headers.
+
+        You may override this method if your application wants to bend the
+        rules, e.g. to strip trailing whitespace, or to recognize MH template
+        separators ('--------').  For convenience (e.g. for code reading from
+        sockets) a line consisting of \r\n also matches.
+        """
+        return line in _blanklines
+
+    def iscomment(self, line):
+        """Determine whether a line should be skipped entirely.
+
+        You may override this method in order to use Message parsing on tagged
+        data in RFC 2822-like formats that support embedded comments or
+        free-text data.
+        """
+        return None
+
+    def getallmatchingheaders(self, name):
+        """Find all header lines matching a given header name.
+
+        Look through the list of headers and find all lines matching a given
+        header name (and their continuation lines).  A list of the lines is
+        returned, without interpretation.  If the header does not occur, an
+        empty list is returned.  If the header occurs multiple times, all
+        occurrences are returned.  Case is not important in the header name.
+        """
+        name = name.lower() + ':'
+        n = len(name)
+        list = []
+        hit = 0
+        for line in self.headers:
+            if line[:n].lower() == name:
+                hit = 1
+            elif not line[:1].isspace():
+                hit = 0
+            if hit:
+                list.append(line)
+        return list
+
+    def getfirstmatchingheader(self, name):
+        """Get the first header line matching name.
+
+        This is similar to getallmatchingheaders, but it returns only the
+        first matching header (and its continuation lines).
+        """
+        name = name.lower() + ':'
+        n = len(name)
+        list = []
+        hit = 0
+        for line in self.headers:
+            if hit:
+                if not line[:1].isspace():
+                    break
+            elif line[:n].lower() == name:
+                hit = 1
+            if hit:
+                list.append(line)
+        return list
+
+    def getrawheader(self, name):
+        """A higher-level interface to getfirstmatchingheader().
+
+        Return a string containing the literal text of the header but with the
+        keyword stripped.  All leading, trailing and embedded whitespace is
+        kept in the string, however.  Return None if the header does not
+        occur.
+        """
+
+        list = self.getfirstmatchingheader(name)
+        if not list:
+            return None
+        list[0] = list[0][len(name) + 1:]
+        return ''.join(list)
+
+    def getheader(self, name, default=None):
+        """Get the header value for a name.
+
+        This is the normal interface: it returns a stripped version of the
+        header value for a given header name, or None if it doesn't exist.
+        This uses the dictionary version which finds the *last* such header.
+        """
+        try:
+            return self.dict[name.lower()]
+        except KeyError:
+            return default
+    get = getheader
+
+    def getheaders(self, name):
+        """Get all values for a header.
+
+        This returns a list of values for headers given more than once; each
+        value in the result list is stripped in the same way as the result of
+        getheader().  If the header is not given, return an empty list.
+        """
+        result = []
+        current = ''
+        have_header = 0
+        for s in self.getallmatchingheaders(name):
+            if s[0].isspace():
+                if current:
+                    current = "%s\n %s" % (current, s.strip())
+                else:
+                    current = s.strip()
+            else:
+                if have_header:
+                    result.append(current)
+                current = s[s.find(":") + 1:].strip()
+                have_header = 1
+        if have_header:
+            result.append(current)
+        return result
+
+    def getaddr(self, name):
+        """Get a single address from a header, as a tuple.
+
+        An example return value:
+        ('Guido van Rossum', 'guido@cwi.nl')
+        """
+        # New, by Ben Escoto
+        alist = self.getaddrlist(name)
+        if alist:
+            return alist[0]
+        else:
+            return (None, None)
+
+    def getaddrlist(self, name):
+        """Get a list of addresses from a header.
+
+        Retrieves a list of addresses from a header, where each address is a
+        tuple as returned by getaddr().  Scans all named headers, so it works
+        properly with multiple To: or Cc: headers for example.
+        """
+        raw = []
+        for h in self.getallmatchingheaders(name):
+            if h[0] in ' \t':
+                raw.append(h)
+            else:
+                if raw:
+                    raw.append(', ')
+                i = h.find(':')
+                if i > 0:
+                    addr = h[i+1:]
+                raw.append(addr)
+        alladdrs = ''.join(raw)
+        a = AddrlistClass(alladdrs)
+        return a.getaddrlist()
+
+    def getdate(self, name):
+        """Retrieve a date field from a header.
+
+        Retrieves a date field from the named header, returning a tuple
+        compatible with time.mktime().
+        """
+        try:
+            data = self[name]
+        except KeyError:
+            return None
+        return parsedate(data)
+
+    def getdate_tz(self, name):
+        """Retrieve a date field from a header as a 10-tuple.
+
+        The first 9 elements make up a tuple compatible with time.mktime(),
+        and the 10th is the offset of the poster's time zone from GMT/UTC.
+        """
+        try:
+            data = self[name]
+        except KeyError:
+            return None
+        return parsedate_tz(data)
+
+
+    # Access as a dictionary (only finds *last* header of each type):
+
+    def __len__(self):
+        """Get the number of headers in a message."""
+        return len(self.dict)
+
+    def __contains__(self, name):
+        return name.lower() in self.dict
+    
+    def __getitem__(self, name):
+        """Get a specific header, as from a dictionary."""
+        return self.dict[name.lower()]
+
+    def __setitem__(self, name, value):
+        """Set the value of a header.
+
+        Note: This is not a perfect inversion of __getitem__, because any
+        changed headers get stuck at the end of the raw-headers list rather
+        than where the altered header was.
+        """
+        del self[name] # Won't fail if it doesn't exist
+        self.dict[name.lower()] = value
+        text = name + ": " + value
+        lines = text.split("\n")
+        for line in lines:
+            self.headers.append(line + "\n")
+
+    def __delitem__(self, name):
+        """Delete all occurrences of a specific header, if it is present."""
+        name = name.lower()
+        if not self.dict.has_key(name):
+            return
+        del self.dict[name]
+        name = name + ':'
+        n = len(name)
+        list = []
+        hit = 0
+        for i in range(len(self.headers)):
+            line = self.headers[i]
+            if line[:n].lower() == name:
+                hit = 1
+            elif not line[:1].isspace():
+                hit = 0
+            if hit:
+                list.append(i)
+        list.reverse()
+        for i in list:
+            del self.headers[i]
+
+    def setdefault(self, name, default=""):
+        lowername = name.lower()
+        if self.dict.has_key(lowername):
+            return self.dict[lowername]
+        else:
+            text = name + ": " + default
+            lines = text.split("\n")
+            for line in lines:
+                self.headers.append(line + "\n")
+            self.dict[lowername] = default
+            return default
+
+    def has_key(self, name):
+        """Determine whether a message contains the named header."""
+        return self.dict.has_key(name.lower())
+
+    def keys(self):
+        """Get all of a message's header field names."""
+        return self.dict.keys()
+
+    def values(self):
+        """Get all of a message's header field values."""
+        return self.dict.values()
+
+    def items(self):
+        """Get all of a message's headers.
+
+        Returns a list of name, value tuples.
+        """
+        return self.dict.items()
+
+    def __str__(self):
+        str = ''
+        for hdr in self.headers:
+            str = str + hdr
+        return str
+
+
+# Utility functions
+# -----------------
+
+# XXX Should fix unquote() and quote() to be really conformant.
+# XXX The inverses of the parse functions may also be useful.
+
+
+def unquote(str):
+    """Remove quotes from a string."""
+    if len(str) > 1:
+        if str[0] == '"' and str[-1:] == '"':
+            return str[1:-1]
+        if str[0] == '<' and str[-1:] == '>':
+            return str[1:-1]
+    return str
+
+
+def quote(str):
+    """Add quotes around a string."""
+    return str.replace('\\', '\\\\').replace('"', '\\"')
+
+
+def parseaddr(address):
+    """Parse an address into a (realname, mailaddr) tuple."""
+    a = AddressList(address)
+    list = a.addresslist
+    if not list:
+        return (None, None)
+    else:
+        return list[0]
+
+
+class AddrlistClass:
+    """Address parser class by Ben Escoto.
+
+    To understand what this class does, it helps to have a copy of
+    RFC 2822 in front of you.
+
+    http://www.faqs.org/rfcs/rfc2822.html
+
+    Note: this class interface is deprecated and may be removed in the future.
+    Use rfc822.AddressList instead.
+    """
+
+    def __init__(self, field):
+        """Initialize a new instance.
+
+        `field' is an unparsed address header field, containing one or more
+        addresses.
+        """
+        self.specials = '()<>@,:;.\"[]'
+        self.pos = 0
+        self.LWS = ' \t'
+        self.CR = '\r\n'
+        self.atomends = self.specials + self.LWS + self.CR
+        # Note that RFC 2822 now specifies `.' as obs-phrase, meaning that it
+        # is obsolete syntax.  RFC 2822 requires that we recognize obsolete
+        # syntax, so allow dots in phrases.
+        self.phraseends = self.atomends.replace('.', '')
+        self.field = field
+        self.commentlist = []
+
+    def gotonext(self):
+        """Parse up to the start of the next address."""
+        while self.pos < len(self.field):
+            if self.field[self.pos] in self.LWS + '\n\r':
+                self.pos = self.pos + 1
+            elif self.field[self.pos] == '(':
+                self.commentlist.append(self.getcomment())
+            else: break
+
+    def getaddrlist(self):
+        """Parse all addresses.
+
+        Returns a list containing all of the addresses.
+        """
+        result = []
+        while 1:
+            ad = self.getaddress()
+            if ad:
+                result += ad
+            else:
+                break
+        return result
+
+    def getaddress(self):
+        """Parse the next address."""
+        self.commentlist = []
+        self.gotonext()
+
+        oldpos = self.pos
+        oldcl = self.commentlist
+        plist = self.getphraselist()
+
+        self.gotonext()
+        returnlist = []
+
+        if self.pos >= len(self.field):
+            # Bad email address technically, no domain.
+            if plist:
+                returnlist = [(' '.join(self.commentlist), plist[0])]
+
+        elif self.field[self.pos] in '.@':
+            # email address is just an addrspec
+            # this isn't very efficient since we start over
+            self.pos = oldpos
+            self.commentlist = oldcl
+            addrspec = self.getaddrspec()
+            returnlist = [(' '.join(self.commentlist), addrspec)]
+
+        elif self.field[self.pos] == ':':
+            # address is a group
+            returnlist = []
+
+            fieldlen = len(self.field)
+            self.pos = self.pos + 1
+            while self.pos < len(self.field):
+                self.gotonext()
+                if self.pos < fieldlen and self.field[self.pos] == ';':
+                    self.pos = self.pos + 1
+                    break
+                returnlist = returnlist + self.getaddress()
+
+        elif self.field[self.pos] == '<':
+            # Address is a phrase then a route addr
+            routeaddr = self.getrouteaddr()
+
+            if self.commentlist:
+                returnlist = [(' '.join(plist) + ' (' + \
+                         ' '.join(self.commentlist) + ')', routeaddr)]
+            else: returnlist = [(' '.join(plist), routeaddr)]
+
+        else:
+            if plist:
+                returnlist = [(' '.join(self.commentlist), plist[0])]
+            elif self.field[self.pos] in self.specials:
+                self.pos = self.pos + 1
+
+        self.gotonext()
+        if self.pos < len(self.field) and self.field[self.pos] == ',':
+            self.pos = self.pos + 1
+        return returnlist
+
+    def getrouteaddr(self):
+        """Parse a route address (Return-path value).
+
+        This method just skips all the route stuff and returns the addrspec.
+        """
+        if self.field[self.pos] != '<':
+            return
+
+        expectroute = 0
+        self.pos = self.pos + 1
+        self.gotonext()
+        adlist = ""
+        while self.pos < len(self.field):
+            if expectroute:
+                self.getdomain()
+                expectroute = 0
+            elif self.field[self.pos] == '>':
+                self.pos = self.pos + 1
+                break
+            elif self.field[self.pos] == '@':
+                self.pos = self.pos + 1
+                expectroute = 1
+            elif self.field[self.pos] == ':':
+                self.pos = self.pos + 1
+            else:
+                adlist = self.getaddrspec()
+                self.pos = self.pos + 1
+                break
+            self.gotonext()
+
+        return adlist
+
+    def getaddrspec(self):
+        """Parse an RFC 2822 addr-spec."""
+        aslist = []
+
+        self.gotonext()
+        while self.pos < len(self.field):
+            if self.field[self.pos] == '.':
+                aslist.append('.')
+                self.pos = self.pos + 1
+            elif self.field[self.pos] == '"':
+                aslist.append('"%s"' % self.getquote())
+            elif self.field[self.pos] in self.atomends:
+                break
+            else: aslist.append(self.getatom())
+            self.gotonext()
+
+        if self.pos >= len(self.field) or self.field[self.pos] != '@':
+            return ''.join(aslist)
+
+        aslist.append('@')
+        self.pos = self.pos + 1
+        self.gotonext()
+        return ''.join(aslist) + self.getdomain()
+
+    def getdomain(self):
+        """Get the complete domain name from an address."""
+        sdlist = []
+        while self.pos < len(self.field):
+            if self.field[self.pos] in self.LWS:
+                self.pos = self.pos + 1
+            elif self.field[self.pos] == '(':
+                self.commentlist.append(self.getcomment())
+            elif self.field[self.pos] == '[':
+                sdlist.append(self.getdomainliteral())
+            elif self.field[self.pos] == '.':
+                self.pos = self.pos + 1
+                sdlist.append('.')
+            elif self.field[self.pos] in self.atomends:
+                break
+            else: sdlist.append(self.getatom())
+        return ''.join(sdlist)
+
+    def getdelimited(self, beginchar, endchars, allowcomments = 1):
+        """Parse a header fragment delimited by special characters.
+
+        `beginchar' is the start character for the fragment.  If self is not
+        looking at an instance of `beginchar' then getdelimited returns the
+        empty string.
+
+        `endchars' is a sequence of allowable end-delimiting characters.
+        Parsing stops when one of these is encountered.
+
+        If `allowcomments' is non-zero, embedded RFC 2822 comments are allowed
+        within the parsed fragment.
+        """
+        if self.field[self.pos] != beginchar:
+            return ''
+
+        slist = ['']
+        quote = 0
+        self.pos = self.pos + 1
+        while self.pos < len(self.field):
+            if quote == 1:
+                slist.append(self.field[self.pos])
+                quote = 0
+            elif self.field[self.pos] in endchars:
+                self.pos = self.pos + 1
+                break
+            elif allowcomments and self.field[self.pos] == '(':
+                slist.append(self.getcomment())
+            elif self.field[self.pos] == '\\':
+                quote = 1
+            else:
+                slist.append(self.field[self.pos])
+            self.pos = self.pos + 1
+
+        return ''.join(slist)
+
+    def getquote(self):
+        """Get a quote-delimited fragment from self's field."""
+        return self.getdelimited('"', '"\r', 0)
+
+    def getcomment(self):
+        """Get a parenthesis-delimited fragment from self's field."""
+        return self.getdelimited('(', ')\r', 1)
+
+    def getdomainliteral(self):
+        """Parse an RFC 2822 domain-literal."""
+        return '[%s]' % self.getdelimited('[', ']\r', 0)
+
+    def getatom(self, atomends=None):
+        """Parse an RFC 2822 atom.
+
+        Optional atomends specifies a different set of end token delimiters
+        (the default is to use self.atomends).  This is used e.g. in
+        getphraselist() since phrase endings must not include the `.' (which
+        is legal in phrases)."""
+        atomlist = ['']
+        if atomends is None:
+            atomends = self.atomends
+
+        while self.pos < len(self.field):
+            if self.field[self.pos] in atomends:
+                break
+            else: atomlist.append(self.field[self.pos])
+            self.pos = self.pos + 1
+
+        return ''.join(atomlist)
+
+    def getphraselist(self):
+        """Parse a sequence of RFC 2822 phrases.
+
+        A phrase is a sequence of words, which are in turn either RFC 2822
+        atoms or quoted-strings.  Phrases are canonicalized by squeezing all
+        runs of continuous whitespace into one space.
+        """
+        plist = []
+
+        while self.pos < len(self.field):
+            if self.field[self.pos] in self.LWS:
+                self.pos = self.pos + 1
+            elif self.field[self.pos] == '"':
+                plist.append(self.getquote())
+            elif self.field[self.pos] == '(':
+                self.commentlist.append(self.getcomment())
+            elif self.field[self.pos] in self.phraseends:
+                break
+            else:
+                plist.append(self.getatom(self.phraseends))
+
+        return plist
+
+class AddressList(AddrlistClass):
+    """An AddressList encapsulates a list of parsed RFC 2822 addresses."""
+    def __init__(self, field):
+        AddrlistClass.__init__(self, field)
+        if field:
+            self.addresslist = self.getaddrlist()
+        else:
+            self.addresslist = []
+
+    def __len__(self):
+        return len(self.addresslist)
+
+    def __str__(self):
+        return ", ".join(map(dump_address_pair, self.addresslist))
+
+    def __add__(self, other):
+        # Set union
+        newaddr = AddressList(None)
+        newaddr.addresslist = self.addresslist[:]
+        for x in other.addresslist:
+            if not x in self.addresslist:
+                newaddr.addresslist.append(x)
+        return newaddr
+
+    def __iadd__(self, other):
+        # Set union, in-place
+        for x in other.addresslist:
+            if not x in self.addresslist:
+                self.addresslist.append(x)
+        return self
+
+    def __sub__(self, other):
+        # Set difference
+        newaddr = AddressList(None)
+        for x in self.addresslist:
+            if not x in other.addresslist:
+                newaddr.addresslist.append(x)
+        return newaddr
+
+    def __isub__(self, other):
+        # Set difference, in-place
+        for x in other.addresslist:
+            if x in self.addresslist:
+                self.addresslist.remove(x)
+        return self
+
+    def __getitem__(self, index):
+        # Make indexing, slices, and 'in' work
+        return self.addresslist[index]
+
+def dump_address_pair(pair):
+    """Dump a (name, address) pair in a canonicalized form."""
+    if pair[0]:
+        return '"' + pair[0] + '" <' + pair[1] + '>'
+    else:
+        return pair[1]
+
+# Parse a date field
+
+_monthnames = ['jan', 'feb', 'mar', 'apr', 'may', 'jun', 'jul',
+               'aug', 'sep', 'oct', 'nov', 'dec',
+               'january', 'february', 'march', 'april', 'may', 'june', 'july',
+               'august', 'september', 'october', 'november', 'december']
+_daynames = ['mon', 'tue', 'wed', 'thu', 'fri', 'sat', 'sun']
+
+# The timezone table does not include the military time zones defined
+# in RFC822, other than Z.  According to RFC1123, the description in
+# RFC822 gets the signs wrong, so we can't rely on any such time
+# zones.  RFC1123 recommends that numeric timezone indicators be used
+# instead of timezone names.
+
+_timezones = {'UT':0, 'UTC':0, 'GMT':0, 'Z':0,
+              'AST': -400, 'ADT': -300,  # Atlantic (used in Canada)
+              'EST': -500, 'EDT': -400,  # Eastern
+              'CST': -600, 'CDT': -500,  # Central
+              'MST': -700, 'MDT': -600,  # Mountain
+              'PST': -800, 'PDT': -700   # Pacific
+              }
+
+
+def parsedate_tz(data):
+    """Convert a date string to a time tuple.
+
+    Accounts for military timezones.
+    """
+    if not data:
+        return None
+    data = data.split()
+    if data[0][-1] in (',', '.') or data[0].lower() in _daynames:
+        # There's a dayname here. Skip it
+        del data[0]
+    if len(data) == 3: # RFC 850 date, deprecated
+        stuff = data[0].split('-')
+        if len(stuff) == 3:
+            data = stuff + data[1:]
+    if len(data) == 4:
+        s = data[3]
+        i = s.find('+')
+        if i > 0:
+            data[3:] = [s[:i], s[i+1:]]
+        else:
+            data.append('') # Dummy tz
+    if len(data) < 5:
+        return None
+    data = data[:5]
+    [dd, mm, yy, tm, tz] = data
+    mm = mm.lower()
+    if not mm in _monthnames:
+        dd, mm = mm, dd.lower()
+        if not mm in _monthnames:
+            return None
+    mm = _monthnames.index(mm)+1
+    if mm > 12: mm = mm - 12
+    if dd[-1] == ',':
+        dd = dd[:-1]
+    i = yy.find(':')
+    if i > 0:
+        yy, tm = tm, yy
+    if yy[-1] == ',':
+        yy = yy[:-1]
+    if not yy[0].isdigit():
+        yy, tz = tz, yy
+    if tm[-1] == ',':
+        tm = tm[:-1]
+    tm = tm.split(':')
+    if len(tm) == 2:
+        [thh, tmm] = tm
+        tss = '0'
+    elif len(tm) == 3:
+        [thh, tmm, tss] = tm
+    else:
+        return None
+    try:
+        yy = int(yy)
+        dd = int(dd)
+        thh = int(thh)
+        tmm = int(tmm)
+        tss = int(tss)
+    except ValueError:
+        return None
+    tzoffset = None
+    tz = tz.upper()
+    if _timezones.has_key(tz):
+        tzoffset = _timezones[tz]
+    else:
+        try:
+            tzoffset = int(tz)
+        except ValueError:
+            pass
+    # Convert a timezone offset into seconds ; -0500 -> -18000
+    if tzoffset:
+        if tzoffset < 0:
+            tzsign = -1
+            tzoffset = -tzoffset
+        else:
+            tzsign = 1
+        tzoffset = tzsign * ( (tzoffset//100)*3600 + (tzoffset % 100)*60)
+    tuple = (yy, mm, dd, thh, tmm, tss, 0, 0, 0, tzoffset)
+    return tuple
+
+
+def parsedate(data):
+    """Convert a time string to a time tuple."""
+    t = parsedate_tz(data)
+    if type(t) == type( () ):
+        return t[:9]
+    else: return t
+
+
+def mktime_tz(data):
+    """Turn a 10-tuple as returned by parsedate_tz() into a UTC timestamp."""
+    if data[9] is None:
+        # No zone info, so localtime is better assumption than GMT
+        return time.mktime(data[:8] + (-1,))
+    else:
+        t = time.mktime(data[:8] + (0,))
+        return t - data[9] - time.timezone
+
+def formatdate(timeval=None):
+    """Returns time format preferred for Internet standards.
+
+    Sun, 06 Nov 1994 08:49:37 GMT  ; RFC 822, updated by RFC 1123
+
+    According to RFC 1123, day and month names must always be in
+    English.  If not for that, this code could use strftime().  It
+    can't because strftime() honors the locale and could generated
+    non-English names.
+    """
+    if timeval is None:
+        timeval = time.time()
+    timeval = time.gmtime(timeval)
+    return "%s, %02d %s %04d %02d:%02d:%02d GMT" % (
+            ["Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"][timeval[6]],
+            timeval[2],
+            ["Jan", "Feb", "Mar", "Apr", "May", "Jun",
+             "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"][timeval[1]-1],
+                                timeval[0], timeval[3], timeval[4], timeval[5])
+
+
+# When used as script, run a small test program.
+# The first command line argument must be a filename containing one
+# message in RFC-822 format.
+
+if __name__ == '__main__':
+    import sys, os
+    file = os.path.join(os.environ['HOME'], 'Mail/inbox/1')
+    if sys.argv[1:]: file = sys.argv[1]
+    f = open(file, 'r')
+    m = Message(f)
+    print 'From:', m.getaddr('from')
+    print 'To:', m.getaddrlist('to')
+    print 'Subject:', m.getheader('subject')
+    print 'Date:', m.getheader('date')
+    date = m.getdate_tz('date')
+    tz = date[-1]
+    date = time.localtime(mktime_tz(date))
+    if date:
+        print 'ParsedDate:', time.asctime(date),
+        hhmmss = tz
+        hhmm, ss = divmod(hhmmss, 60)
+        hh, mm = divmod(hhmm, 60)
+        print "%+03d%02d" % (hh, mm),
+        if ss: print ".%02d" % ss,
+        print
+    else:
+        print 'ParsedDate:', None
+    m.rewindbody()
+    n = 0
+    while f.readline():
+        n = n + 1
+    print 'Lines:', n
+    print '-'*70
+    print 'len =', len(m)
+    if m.has_key('Date'): print 'Date =', m['Date']
+    if m.has_key('X-Nonsense'): pass
+    print 'keys =', m.keys()
+    print 'values =', m.values()
+    print 'items =', m.items()