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Diffstat (limited to 'Lib/email/message.py')
| -rw-r--r-- | Lib/email/message.py | 773 |
1 files changed, 773 insertions, 0 deletions
diff --git a/Lib/email/message.py b/Lib/email/message.py new file mode 100644 index 0000000..50d90b4 --- /dev/null +++ b/Lib/email/message.py @@ -0,0 +1,773 @@ +# Copyright (C) 2001-2006 Python Software Foundation +# Author: Barry Warsaw +# Contact: email-sig@python.org + +"""Basic message object for the email package object model.""" + +__all__ = ['Message'] + +import re +import uu +import binascii +import warnings +from cStringIO import StringIO + +# Intrapackage imports +import email.charset +from email import utils +from email import errors + +SEMISPACE = '; ' + +# Regular expression used to split header parameters. BAW: this may be too +# simple. It isn't strictly RFC 2045 (section 5.1) compliant, but it catches +# most headers found in the wild. We may eventually need a full fledged +# parser eventually. +paramre = re.compile(r'\s*;\s*') +# Regular expression that matches `special' characters in parameters, the +# existance of which force quoting of the parameter value. +tspecials = re.compile(r'[ \(\)<>@,;:\\"/\[\]\?=]') + + + +# Helper functions +def _formatparam(param, value=None, quote=True): + """Convenience function to format and return a key=value pair. + + This will quote the value if needed or if quote is true. + """ + if value is not None and len(value) > 0: + # A tuple is used for RFC 2231 encoded parameter values where items + # are (charset, language, value). charset is a string, not a Charset + # instance. + if isinstance(value, tuple): + # Encode as per RFC 2231 + param += '*' + value = utils.encode_rfc2231(value[2], value[0], value[1]) + # BAW: Please check this. I think that if quote is set it should + # force quoting even if not necessary. + if quote or tspecials.search(value): + return '%s="%s"' % (param, utils.quote(value)) + else: + return '%s=%s' % (param, value) + else: + return param + +def _parseparam(s): + plist = [] + while s[:1] == ';': + s = s[1:] + end = s.find(';') + while end > 0 and s.count('"', 0, end) % 2: + end = s.find(';', end + 1) + if end < 0: + end = len(s) + f = s[:end] + if '=' in f: + i = f.index('=') + f = f[:i].strip().lower() + '=' + f[i+1:].strip() + plist.append(f.strip()) + s = s[end:] + return plist + + +def _unquotevalue(value): + # This is different than utils.collapse_rfc2231_value() because it doesn't + # try to convert the value to a unicode. Message.get_param() and + # Message.get_params() are both currently defined to return the tuple in + # the face of RFC 2231 parameters. + if isinstance(value, tuple): + return value[0], value[1], utils.unquote(value[2]) + else: + return utils.unquote(value) + + + +class Message: + """Basic message object. + + A message object is defined as something that has a bunch of RFC 2822 + headers and a payload. It may optionally have an envelope header + (a.k.a. Unix-From or From_ header). If the message is a container (i.e. a + multipart or a message/rfc822), then the payload is a list of Message + objects, otherwise it is a string. + + Message objects implement part of the `mapping' interface, which assumes + there is exactly one occurrance of the header per message. Some headers + do in fact appear multiple times (e.g. Received) and for those headers, + you must use the explicit API to set or get all the headers. Not all of + the mapping methods are implemented. + """ + def __init__(self): + self._headers = [] + self._unixfrom = None + self._payload = None + self._charset = None + # Defaults for multipart messages + self.preamble = self.epilogue = None + self.defects = [] + # Default content type + self._default_type = 'text/plain' + + def __str__(self): + """Return the entire formatted message as a string. + This includes the headers, body, and envelope header. + """ + return self.as_string(unixfrom=True) + + def as_string(self, unixfrom=False): + """Return the entire formatted message as a string. + Optional `unixfrom' when True, means include the Unix From_ envelope + header. + + This is a convenience method and may not generate the message exactly + as you intend because by default it mangles lines that begin with + "From ". For more flexibility, use the flatten() method of a + Generator instance. + """ + from email.Generator import Generator + fp = StringIO() + g = Generator(fp) + g.flatten(self, unixfrom=unixfrom) + return fp.getvalue() + + def is_multipart(self): + """Return True if the message consists of multiple parts.""" + return isinstance(self._payload, list) + + # + # Unix From_ line + # + def set_unixfrom(self, unixfrom): + self._unixfrom = unixfrom + + def get_unixfrom(self): + return self._unixfrom + + # + # Payload manipulation. + # + def attach(self, payload): + """Add the given payload to the current payload. + + The current payload will always be a list of objects after this method + is called. If you want to set the payload to a scalar object, use + set_payload() instead. + """ + if self._payload is None: + self._payload = [payload] + else: + self._payload.append(payload) + + def get_payload(self, i=None, decode=False): + """Return a reference to the payload. + + The payload will either be a list object or a string. If you mutate + the list object, you modify the message's payload in place. Optional + i returns that index into the payload. + + Optional decode is a flag indicating whether the payload should be + decoded or not, according to the Content-Transfer-Encoding header + (default is False). + + When True and the message is not a multipart, the payload will be + decoded if this header's value is `quoted-printable' or `base64'. If + some other encoding is used, or the header is missing, or if the + payload has bogus data (i.e. bogus base64 or uuencoded data), the + payload is returned as-is. + + If the message is a multipart and the decode flag is True, then None + is returned. + """ + if i is None: + payload = self._payload + elif not isinstance(self._payload, list): + raise TypeError('Expected list, got %s' % type(self._payload)) + else: + payload = self._payload[i] + if decode: + if self.is_multipart(): + return None + cte = self.get('content-transfer-encoding', '').lower() + if cte == 'quoted-printable': + return utils._qdecode(payload) + elif cte == 'base64': + try: + return utils._bdecode(payload) + except binascii.Error: + # Incorrect padding + return payload + elif cte in ('x-uuencode', 'uuencode', 'uue', 'x-uue'): + sfp = StringIO() + try: + uu.decode(StringIO(payload+'\n'), sfp, quiet=True) + payload = sfp.getvalue() + except uu.Error: + # Some decoding problem + return payload + # Everything else, including encodings with 8bit or 7bit are returned + # unchanged. + return payload + + def set_payload(self, payload, charset=None): + """Set the payload to the given value. + + Optional charset sets the message's default character set. See + set_charset() for details. + """ + self._payload = payload + if charset is not None: + self.set_charset(charset) + + def set_charset(self, charset): + """Set the charset of the payload to a given character set. + + charset can be a Charset instance, a string naming a character set, or + None. If it is a string it will be converted to a Charset instance. + If charset is None, the charset parameter will be removed from the + Content-Type field. Anything else will generate a TypeError. + + The message will be assumed to be of type text/* encoded with + charset.input_charset. It will be converted to charset.output_charset + and encoded properly, if needed, when generating the plain text + representation of the message. MIME headers (MIME-Version, + Content-Type, Content-Transfer-Encoding) will be added as needed. + + """ + if charset is None: + self.del_param('charset') + self._charset = None + return + if isinstance(charset, str): + charset = email.charset.Charset(charset) + if not isinstance(charset, email.charset.Charset): + raise TypeError(charset) + # BAW: should we accept strings that can serve as arguments to the + # Charset constructor? + self._charset = charset + if not self.has_key('MIME-Version'): + self.add_header('MIME-Version', '1.0') + if not self.has_key('Content-Type'): + self.add_header('Content-Type', 'text/plain', + charset=charset.get_output_charset()) + else: + self.set_param('charset', charset.get_output_charset()) + if str(charset) <> charset.get_output_charset(): + self._payload = charset.body_encode(self._payload) + if not self.has_key('Content-Transfer-Encoding'): + cte = charset.get_body_encoding() + try: + cte(self) + except TypeError: + self._payload = charset.body_encode(self._payload) + self.add_header('Content-Transfer-Encoding', cte) + + def get_charset(self): + """Return the Charset instance associated with the message's payload. + """ + return self._charset + + # + # MAPPING INTERFACE (partial) + # + def __len__(self): + """Return the total number of headers, including duplicates.""" + return len(self._headers) + + def __getitem__(self, name): + """Get a header value. + + Return None if the header is missing instead of raising an exception. + + Note that if the header appeared multiple times, exactly which + occurrance gets returned is undefined. Use get_all() to get all + the values matching a header field name. + """ + return self.get(name) + + def __setitem__(self, name, val): + """Set the value of a header. + + Note: this does not overwrite an existing header with the same field + name. Use __delitem__() first to delete any existing headers. + """ + self._headers.append((name, val)) + + def __delitem__(self, name): + """Delete all occurrences of a header, if present. + + Does not raise an exception if the header is missing. + """ + name = name.lower() + newheaders = [] + for k, v in self._headers: + if k.lower() <> name: + newheaders.append((k, v)) + self._headers = newheaders + + def __contains__(self, name): + return name.lower() in [k.lower() for k, v in self._headers] + + def has_key(self, name): + """Return true if the message contains the header.""" + missing = object() + return self.get(name, missing) is not missing + + def keys(self): + """Return a list of all the message's header field names. + + These will be sorted in the order they appeared in the original + message, or were added to the message, and may contain duplicates. + Any fields deleted and re-inserted are always appended to the header + list. + """ + return [k for k, v in self._headers] + + def values(self): + """Return a list of all the message's header values. + + These will be sorted in the order they appeared in the original + message, or were added to the message, and may contain duplicates. + Any fields deleted and re-inserted are always appended to the header + list. + """ + return [v for k, v in self._headers] + + def items(self): + """Get all the message's header fields and values. + + These will be sorted in the order they appeared in the original + message, or were added to the message, and may contain duplicates. + Any fields deleted and re-inserted are always appended to the header + list. + """ + return self._headers[:] + + def get(self, name, failobj=None): + """Get a header value. + + Like __getitem__() but return failobj instead of None when the field + is missing. + """ + name = name.lower() + for k, v in self._headers: + if k.lower() == name: + return v + return failobj + + # + # Additional useful stuff + # + + def get_all(self, name, failobj=None): + """Return a list of all the values for the named field. + + These will be sorted in the order they appeared in the original + message, and may contain duplicates. Any fields deleted and + re-inserted are always appended to the header list. + + If no such fields exist, failobj is returned (defaults to None). + """ + values = [] + name = name.lower() + for k, v in self._headers: + if k.lower() == name: + values.append(v) + if not values: + return failobj + return values + + def add_header(self, _name, _value, **_params): + """Extended header setting. + + name is the header field to add. keyword arguments can be used to set + additional parameters for the header field, with underscores converted + to dashes. Normally the parameter will be added as key="value" unless + value is None, in which case only the key will be added. + + Example: + + msg.add_header('content-disposition', 'attachment', filename='bud.gif') + """ + parts = [] + for k, v in _params.items(): + if v is None: + parts.append(k.replace('_', '-')) + else: + parts.append(_formatparam(k.replace('_', '-'), v)) + if _value is not None: + parts.insert(0, _value) + self._headers.append((_name, SEMISPACE.join(parts))) + + def replace_header(self, _name, _value): + """Replace a header. + + Replace the first matching header found in the message, retaining + header order and case. If no matching header was found, a KeyError is + raised. + """ + _name = _name.lower() + for i, (k, v) in zip(range(len(self._headers)), self._headers): + if k.lower() == _name: + self._headers[i] = (k, _value) + break + else: + raise KeyError(_name) + + # + # Use these three methods instead of the three above. + # + + def get_content_type(self): + """Return the message's content type. + + The returned string is coerced to lower case of the form + `maintype/subtype'. If there was no Content-Type header in the + message, the default type as given by get_default_type() will be + returned. Since according to RFC 2045, messages always have a default + type this will always return a value. + + RFC 2045 defines a message's default type to be text/plain unless it + appears inside a multipart/digest container, in which case it would be + message/rfc822. + """ + missing = object() + value = self.get('content-type', missing) + if value is missing: + # This should have no parameters + return self.get_default_type() + ctype = paramre.split(value)[0].lower().strip() + # RFC 2045, section 5.2 says if its invalid, use text/plain + if ctype.count('/') <> 1: + return 'text/plain' + return ctype + + def get_content_maintype(self): + """Return the message's main content type. + + This is the `maintype' part of the string returned by + get_content_type(). + """ + ctype = self.get_content_type() + return ctype.split('/')[0] + + def get_content_subtype(self): + """Returns the message's sub-content type. + + This is the `subtype' part of the string returned by + get_content_type(). + """ + ctype = self.get_content_type() + return ctype.split('/')[1] + + def get_default_type(self): + """Return the `default' content type. + + Most messages have a default content type of text/plain, except for + messages that are subparts of multipart/digest containers. Such + subparts have a default content type of message/rfc822. + """ + return self._default_type + + def set_default_type(self, ctype): + """Set the `default' content type. + + ctype should be either "text/plain" or "message/rfc822", although this + is not enforced. The default content type is not stored in the + Content-Type header. + """ + self._default_type = ctype + + def _get_params_preserve(self, failobj, header): + # Like get_params() but preserves the quoting of values. BAW: + # should this be part of the public interface? + missing = object() + value = self.get(header, missing) + if value is missing: + return failobj + params = [] + for p in _parseparam(';' + value): + try: + name, val = p.split('=', 1) + name = name.strip() + val = val.strip() + except ValueError: + # Must have been a bare attribute + name = p.strip() + val = '' + params.append((name, val)) + params = utils.decode_params(params) + return params + + def get_params(self, failobj=None, header='content-type', unquote=True): + """Return the message's Content-Type parameters, as a list. + + The elements of the returned list are 2-tuples of key/value pairs, as + split on the `=' sign. The left hand side of the `=' is the key, + while the right hand side is the value. If there is no `=' sign in + the parameter the value is the empty string. The value is as + described in the get_param() method. + + Optional failobj is the object to return if there is no Content-Type + header. Optional header is the header to search instead of + Content-Type. If unquote is True, the value is unquoted. + """ + missing = object() + params = self._get_params_preserve(missing, header) + if params is missing: + return failobj + if unquote: + return [(k, _unquotevalue(v)) for k, v in params] + else: + return params + + def get_param(self, param, failobj=None, header='content-type', + unquote=True): + """Return the parameter value if found in the Content-Type header. + + Optional failobj is the object to return if there is no Content-Type + header, or the Content-Type header has no such parameter. Optional + header is the header to search instead of Content-Type. + + Parameter keys are always compared case insensitively. The return + value can either be a string, or a 3-tuple if the parameter was RFC + 2231 encoded. When it's a 3-tuple, the elements of the value are of + the form (CHARSET, LANGUAGE, VALUE). Note that both CHARSET and + LANGUAGE can be None, in which case you should consider VALUE to be + encoded in the us-ascii charset. You can usually ignore LANGUAGE. + + Your application should be prepared to deal with 3-tuple return + values, and can convert the parameter to a Unicode string like so: + + param = msg.get_param('foo') + if isinstance(param, tuple): + param = unicode(param[2], param[0] or 'us-ascii') + + In any case, the parameter value (either the returned string, or the + VALUE item in the 3-tuple) is always unquoted, unless unquote is set + to False. + """ + if not self.has_key(header): + return failobj + for k, v in self._get_params_preserve(failobj, header): + if k.lower() == param.lower(): + if unquote: + return _unquotevalue(v) + else: + return v + return failobj + + def set_param(self, param, value, header='Content-Type', requote=True, + charset=None, language=''): + """Set a parameter in the Content-Type header. + + If the parameter already exists in the header, its value will be + replaced with the new value. + + If header is Content-Type and has not yet been defined for this + message, it will be set to "text/plain" and the new parameter and + value will be appended as per RFC 2045. + + An alternate header can specified in the header argument, and all + parameters will be quoted as necessary unless requote is False. + + If charset is specified, the parameter will be encoded according to RFC + 2231. Optional language specifies the RFC 2231 language, defaulting + to the empty string. Both charset and language should be strings. + """ + if not isinstance(value, tuple) and charset: + value = (charset, language, value) + + if not self.has_key(header) and header.lower() == 'content-type': + ctype = 'text/plain' + else: + ctype = self.get(header) + if not self.get_param(param, header=header): + if not ctype: + ctype = _formatparam(param, value, requote) + else: + ctype = SEMISPACE.join( + [ctype, _formatparam(param, value, requote)]) + else: + ctype = '' + for old_param, old_value in self.get_params(header=header, + unquote=requote): + append_param = '' + if old_param.lower() == param.lower(): + append_param = _formatparam(param, value, requote) + else: + append_param = _formatparam(old_param, old_value, requote) + if not ctype: + ctype = append_param + else: + ctype = SEMISPACE.join([ctype, append_param]) + if ctype <> self.get(header): + del self[header] + self[header] = ctype + + def del_param(self, param, header='content-type', requote=True): + """Remove the given parameter completely from the Content-Type header. + + The header will be re-written in place without the parameter or its + value. All values will be quoted as necessary unless requote is + False. Optional header specifies an alternative to the Content-Type + header. + """ + if not self.has_key(header): + return + new_ctype = '' + for p, v in self.get_params(header=header, unquote=requote): + if p.lower() <> param.lower(): + if not new_ctype: + new_ctype = _formatparam(p, v, requote) + else: + new_ctype = SEMISPACE.join([new_ctype, + _formatparam(p, v, requote)]) + if new_ctype <> self.get(header): + del self[header] + self[header] = new_ctype + + def set_type(self, type, header='Content-Type', requote=True): + """Set the main type and subtype for the Content-Type header. + + type must be a string in the form "maintype/subtype", otherwise a + ValueError is raised. + + This method replaces the Content-Type header, keeping all the + parameters in place. If requote is False, this leaves the existing + header's quoting as is. Otherwise, the parameters will be quoted (the + default). + + An alternative header can be specified in the header argument. When + the Content-Type header is set, we'll always also add a MIME-Version + header. + """ + # BAW: should we be strict? + if not type.count('/') == 1: + raise ValueError + # Set the Content-Type, you get a MIME-Version + if header.lower() == 'content-type': + del self['mime-version'] + self['MIME-Version'] = '1.0' + if not self.has_key(header): + self[header] = type + return + params = self.get_params(header=header, unquote=requote) + del self[header] + self[header] = type + # Skip the first param; it's the old type. + for p, v in params[1:]: + self.set_param(p, v, header, requote) + + def get_filename(self, failobj=None): + """Return the filename associated with the payload if present. + + The filename is extracted from the Content-Disposition header's + `filename' parameter, and it is unquoted. If that header is missing + the `filename' parameter, this method falls back to looking for the + `name' parameter. + """ + missing = object() + filename = self.get_param('filename', missing, 'content-disposition') + if filename is missing: + filename = self.get_param('name', missing, 'content-disposition') + if filename is missing: + return failobj + return utils.collapse_rfc2231_value(filename).strip() + + def get_boundary(self, failobj=None): + """Return the boundary associated with the payload if present. + + The boundary is extracted from the Content-Type header's `boundary' + parameter, and it is unquoted. + """ + missing = object() + boundary = self.get_param('boundary', missing) + if boundary is missing: + return failobj + # RFC 2046 says that boundaries may begin but not end in w/s + return utils.collapse_rfc2231_value(boundary).rstrip() + + def set_boundary(self, boundary): + """Set the boundary parameter in Content-Type to 'boundary'. + + This is subtly different than deleting the Content-Type header and + adding a new one with a new boundary parameter via add_header(). The + main difference is that using the set_boundary() method preserves the + order of the Content-Type header in the original message. + + HeaderParseError is raised if the message has no Content-Type header. + """ + missing = object() + params = self._get_params_preserve(missing, 'content-type') + if params is missing: + # There was no Content-Type header, and we don't know what type + # to set it to, so raise an exception. + raise errors.HeaderParseError('No Content-Type header found') + newparams = [] + foundp = False + for pk, pv in params: + if pk.lower() == 'boundary': + newparams.append(('boundary', '"%s"' % boundary)) + foundp = True + else: + newparams.append((pk, pv)) + if not foundp: + # The original Content-Type header had no boundary attribute. + # Tack one on the end. BAW: should we raise an exception + # instead??? + newparams.append(('boundary', '"%s"' % boundary)) + # Replace the existing Content-Type header with the new value + newheaders = [] + for h, v in self._headers: + if h.lower() == 'content-type': + parts = [] + for k, v in newparams: + if v == '': + parts.append(k) + else: + parts.append('%s=%s' % (k, v)) + newheaders.append((h, SEMISPACE.join(parts))) + + else: + newheaders.append((h, v)) + self._headers = newheaders + + def get_content_charset(self, failobj=None): + """Return the charset parameter of the Content-Type header. + + The returned string is always coerced to lower case. If there is no + Content-Type header, or if that header has no charset parameter, + failobj is returned. + """ + missing = object() + charset = self.get_param('charset', missing) + if charset is missing: + return failobj + if isinstance(charset, tuple): + # RFC 2231 encoded, so decode it, and it better end up as ascii. + pcharset = charset[0] or 'us-ascii' + charset = unicode(charset[2], pcharset).encode('us-ascii') + # RFC 2046, $4.1.2 says charsets are not case sensitive + return charset.lower() + + def get_charsets(self, failobj=None): + """Return a list containing the charset(s) used in this message. + + The returned list of items describes the Content-Type headers' + charset parameter for this message and all the subparts in its + payload. + + Each item will either be a string (the value of the charset parameter + in the Content-Type header of that part) or the value of the + 'failobj' parameter (defaults to None), if the part does not have a + main MIME type of "text", or the charset is not defined. + + The list will contain one string for each part of the message, plus + one for the container message (i.e. self), so that a non-multipart + message will still return a list of length 1. + """ + return [part.get_content_charset(failobj) for part in self.walk()] + + # I.e. def walk(self): ... + from email.Iterators import walk |