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+# RFC-822 message manipulation class.
+#
+# XXX This is only a very rough sketch of a full RFC-822 parser;
+# additional methods are needed to parse addresses and dates, and to
+# tokenize lines according to various other syntax rules.
+#
+# Directions for use:
+#
+# To create a Message object: first open a file, e.g.:
+# fp = open(file, 'r')
+# (or 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 init() method of Message:
+# m = Message().init(fp)
+#
+# 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.
+#
+# See the class definition for lower level access methods.
+#
+# There are also some utility functions here.
+
+
+import regex
+import string
+
+
+class Message:
+
+ # Initialize the class instance and read the headers.
+
+ def init(self, fp):
+ self.fp = fp
+ #
+ try:
+ self.startofheaders = self.fp.tell()
+ except IOError:
+ self.startofheaders = None
+ #
+ self.readheaders()
+ #
+ try:
+ self.startofbody = self.fp.tell()
+ except IOError:
+ self.startofbody = None
+ #
+ return self
+
+
+ # Rewind the file to the start of the body (if seekable).
+
+ def rewindbody(self):
+ self.fp.seek(self.startofbody)
+
+
+ # 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).
+
+ def readheaders(self):
+ self.headers = list = []
+ self.status = ''
+ headerseen = 0
+ while 1:
+ line = self.fp.readline()
+ if not line:
+ self.status = 'EOF in headers'
+ break
+ if self.islast(line):
+ break
+ elif headerseen and line[0] in ' \t':
+ # It's a continuation line.
+ list.append(line)
+ elif regex.match('^[!-9;-~]+:', line):
+ # It's a header line.
+ list.append(line)
+ headerseen = 1
+ else:
+ # It's not a header line; stop here.
+ if not headerseen:
+ self.status = 'No headers'
+ else:
+ self.status = 'Bad header'
+ # Try to undo the read.
+ try:
+ self.fp.seek(-len(line), 1)
+ except IOError:
+ self.status = \
+ self.status + '; bad seek'
+ break
+
+
+ # Method to determine whether a line is a legal end of
+ # RFC-822 headers. You may override this method if your
+ # application wants to bend the rules, e.g. to accept lines
+ # ending in '\r\n', to strip trailing whitespace, or to
+ # recognise MH template separators ('--------').
+
+ def islast(self, line):
+ return line == '\n'
+
+
+ # 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.
+
+ def getallmatchingheaders(self, name):
+ name = string.lower(name) + ':'
+ n = len(name)
+ list = []
+ hit = 0
+ for line in self.headers:
+ if string.lower(line[:n]) == name:
+ hit = 1
+ elif line[:1] not in string.whitespace:
+ hit = 0
+ if hit:
+ list.append(line)
+ return list
+
+
+ # Similar, but return only the first matching header (and its
+ # continuation lines).
+
+ def getfirstmatchingheader(self, name):
+ name = string.lower(name) + ':'
+ n = len(name)
+ list = []
+ hit = 0
+ for line in self.headers:
+ if string.lower(line[:n]) == name:
+ hit = 1
+ elif line[:1] not in string.whitespace:
+ if hit:
+ break
+ if hit:
+ list.append(line)
+ return list
+
+
+ # 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.
+
+ def getrawheader(self, name):
+ list = self.getfirstmatchingheader(name)
+ if not list:
+ return None
+ list[0] = list[0][len(name) + 1:]
+ return string.joinfields(list, '')
+
+
+ # Going one step further: also strip leading and trailing
+ # whitespace.
+
+ def getheader(self, name):
+ text = self.getrawheader(name)
+ if text == None:
+ return None
+ return string.strip(text)
+
+
+ # XXX The next step would be to define self.getaddr(name)
+ # and self.getaddrlist(name) which would parse a header
+ # consisting of a single mail address and a number of mail
+ # addresses, respectively. Lower level functions would be
+ # parseaddr(string) and parseaddrlist(string).
+
+ # XXX Similar, there would be a function self.getdate(name) to
+ # return a date in canonical form (perhaps a number compatible
+ # to time.time()) and a function parsedate(string).
+
+ # XXX The inverses of the parse functions may also be useful.
+
+
+
+
+# Utility functions
+# -----------------
+
+
+# Remove quotes from a string.
+# XXX Should fix this to be really conformant.
+
+def unquote(str):
+ 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