diff options
Diffstat (limited to 'Lib/email/_header_value_parser.py')
| -rw-r--r-- | Lib/email/_header_value_parser.py | 804 |
1 files changed, 801 insertions, 3 deletions
diff --git a/Lib/email/_header_value_parser.py b/Lib/email/_header_value_parser.py index f4a01f1..1924ed1 100644 --- a/Lib/email/_header_value_parser.py +++ b/Lib/email/_header_value_parser.py @@ -68,6 +68,8 @@ XXX: provide complete list of token types. """ import re +import urllib # For urllib.parse.unquote +from collections import namedtuple, OrderedDict from email import _encoded_words as _ew from email import errors from email import utils @@ -83,6 +85,11 @@ ATOM_ENDS = SPECIALS | WSP DOT_ATOM_ENDS = ATOM_ENDS - set('.') # '.', '"', and '(' do not end phrases in order to support obs-phrase PHRASE_ENDS = SPECIALS - set('."(') +TSPECIALS = (SPECIALS | set('/?=')) - set('.') +TOKEN_ENDS = TSPECIALS | WSP +ASPECIALS = TSPECIALS | set("*'%") +ATTRIBUTE_ENDS = ASPECIALS | WSP +EXTENDED_ATTRIBUTE_ENDS = ATTRIBUTE_ENDS - set('%') def quote_string(value): return '"'+str(value).replace('\\', '\\\\').replace('"', r'\"')+'"' @@ -356,8 +363,12 @@ class TokenList(list): self.__class__.__name__, self.token_type) for token in self: - for line in token._pp(indent+' '): - yield line + if not hasattr(token, '_pp'): + yield (indent + ' !! invalid element in token ' + 'list: {!r}'.format(token)) + else: + for line in token._pp(indent+' '): + yield line if self.defects: extra = ' Defects: {}'.format(self.defects) else: @@ -567,6 +578,11 @@ class Atom(TokenList): token_type = 'atom' +class Token(TokenList): + + token_type = 'token' + + class EncodedWord(TokenList): token_type = 'encoded-word' @@ -602,13 +618,19 @@ class QuotedString(TokenList): res.append(x.value) return ''.join(res) + @property + def stripped_value(self): + for token in self: + if token.token_type == 'bare-quoted-string': + return token.value + class BareQuotedString(QuotedString): token_type = 'bare-quoted-string' def __str__(self): - return quote_string(''.join(self)) + return quote_string(''.join(str(x) for x in self)) @property def value(self): @@ -987,6 +1009,180 @@ class DomainLiteral(TokenList): return x.value +class MIMEVersion(TokenList): + + token_type = 'mime-version' + major = None + minor = None + + +class Parameter(TokenList): + + token_type = 'parameter' + sectioned = False + extended = False + charset = 'us-ascii' + + @property + def section_number(self): + # Because the first token, the attribute (name) eats CFWS, the second + # token is always the section if there is one. + return self[1].number if self.sectioned else 0 + + @property + def param_value(self): + # This is part of the "handle quoted extended parameters" hack. + for token in self: + if token.token_type == 'value': + return token.stripped_value + if token.token_type == 'quoted-string': + for token in token: + if token.token_type == 'bare-quoted-string': + for token in token: + if token.token_type == 'value': + return token.stripped_value + return '' + + +class InvalidParameter(Parameter): + + token_type = 'invalid-parameter' + + +class Attribute(TokenList): + + token_type = 'attribute' + + @property + def stripped_value(self): + for token in self: + if token.token_type.endswith('attrtext'): + return token.value + +class Section(TokenList): + + token_type = 'section' + number = None + + +class Value(TokenList): + + token_type = 'value' + + @property + def stripped_value(self): + token = self[0] + if token.token_type == 'cfws': + token = self[1] + if token.token_type.endswith( + ('quoted-string', 'attribute', 'extended-attribute')): + return token.stripped_value + return self.value + + +class MimeParameters(TokenList): + + token_type = 'mime-parameters' + + @property + def params(self): + # The RFC specifically states that the ordering of parameters is not + # guaranteed and may be reordered by the transport layer. So we have + # to assume the RFC 2231 pieces can come in any order. However, we + # output them in the order that we first see a given name, which gives + # us a stable __str__. + params = OrderedDict() + for token in self: + if not token.token_type.endswith('parameter'): + continue + if token[0].token_type != 'attribute': + continue + name = token[0].value.strip() + if name not in params: + params[name] = [] + params[name].append((token.section_number, token)) + for name, parts in params.items(): + parts = sorted(parts) + # XXX: there might be more recovery we could do here if, for + # example, this is really a case of a duplicate attribute name. + value_parts = [] + charset = parts[0][1].charset + for i, (section_number, param) in enumerate(parts): + if section_number != i: + param.defects.append(errors.InvalidHeaderDefect( + "inconsistent multipart parameter numbering")) + value = param.param_value + if param.extended: + try: + value = urllib.parse.unquote_to_bytes(value) + except UnicodeEncodeError: + # source had surrogate escaped bytes. What we do now + # is a bit of an open question. I'm not sure this is + # the best choice, but it is what the old algorithm did + value = urllib.parse.unquote(value, encoding='latin-1') + else: + try: + value = value.decode(charset, 'surrogateescape') + except LookupError: + # XXX: there should really be a custom defect for + # unknown character set to make it easy to find, + # because otherwise unknown charset is a silent + # failure. + value = value.decode('us-ascii', 'surrogateescape') + if utils._has_surrogates(value): + param.defects.append(errors.UndecodableBytesDefect()) + value_parts.append(value) + value = ''.join(value_parts) + yield name, value + + def __str__(self): + params = [] + for name, value in self.params: + if value: + params.append('{}={}'.format(name, quote_string(value))) + else: + params.append(name) + params = '; '.join(params) + return ' ' + params if params else '' + + +class ParameterizedHeaderValue(TokenList): + + @property + def params(self): + for token in reversed(self): + if token.token_type == 'mime-parameters': + return token.params + return {} + + @property + def parts(self): + if self and self[-1].token_type == 'mime-parameters': + # We don't want to start a new line if all of the params don't fit + # after the value, so unwrap the parameter list. + return TokenList(self[:-1] + self[-1]) + return TokenList(self).parts + + +class ContentType(ParameterizedHeaderValue): + + token_type = 'content-type' + maintype = 'text' + subtype = 'plain' + + +class ContentDisposition(ParameterizedHeaderValue): + + token_type = 'content-disposition' + content_disposition = None + + +class ContentTransferEncoding(TokenList): + + token_type = 'content-transfer-encoding' + cte = '7bit' + + class HeaderLabel(TokenList): token_type = 'header-label' @@ -1145,6 +1341,13 @@ _wsp_splitter = re.compile(r'([{}]+)'.format(''.join(WSP))).split _non_atom_end_matcher = re.compile(r"[^{}]+".format( ''.join(ATOM_ENDS).replace('\\','\\\\').replace(']','\]'))).match _non_printable_finder = re.compile(r"[\x00-\x20\x7F]").findall +_non_token_end_matcher = re.compile(r"[^{}]+".format( + ''.join(TOKEN_ENDS).replace('\\','\\\\').replace(']','\]'))).match +_non_attribute_end_matcher = re.compile(r"[^{}]+".format( + ''.join(ATTRIBUTE_ENDS).replace('\\','\\\\').replace(']','\]'))).match +_non_extended_attribute_end_matcher = re.compile(r"[^{}]+".format( + ''.join(EXTENDED_ATTRIBUTE_ENDS).replace( + '\\','\\\\').replace(']','\]'))).match def _validate_xtext(xtext): """If input token contains ASCII non-printables, register a defect.""" @@ -2153,3 +2356,598 @@ def get_address_list(value): address_list.append(ValueTerminal(',', 'list-separator')) value = value[1:] return address_list, value + +# +# XXX: As I begin to add additional header parsers, I'm realizing we probably +# have two level of parser routines: the get_XXX methods that get a token in +# the grammar, and parse_XXX methods that parse an entire field value. So +# get_address_list above should really be a parse_ method, as probably should +# be get_unstructured. +# + +def parse_mime_version(value): + """ mime-version = [CFWS] 1*digit [CFWS] "." [CFWS] 1*digit [CFWS] + + """ + # The [CFWS] is implicit in the RFC 2045 BNF. + # XXX: This routine is a bit verbose, should factor out a get_int method. + mime_version = MIMEVersion() + if not value: + mime_version.defects.append(errors.HeaderMissingRequiredValue( + "Missing MIME version number (eg: 1.0)")) + return mime_version + if value[0] in CFWS_LEADER: + token, value = get_cfws(value) + mime_version.append(token) + if not value: + mime_version.defects.append(errors.HeaderMissingRequiredValue( + "Expected MIME version number but found only CFWS")) + digits = '' + while value and value[0] != '.' and value[0] not in CFWS_LEADER: + digits += value[0] + value = value[1:] + if not digits.isdigit(): + mime_version.defects.append(errors.InvalidHeaderDefect( + "Expected MIME major version number but found {!r}".format(digits))) + mime_version.append(ValueTerminal(digits, 'xtext')) + else: + mime_version.major = int(digits) + mime_version.append(ValueTerminal(digits, 'digits')) + if value and value[0] in CFWS_LEADER: + token, value = get_cfws(value) + mime_version.append(token) + if not value or value[0] != '.': + if mime_version.major is not None: + mime_version.defects.append(errors.InvalidHeaderDefect( + "Incomplete MIME version; found only major number")) + if value: + mime_version.append(ValueTerminal(value, 'xtext')) + return mime_version + mime_version.append(ValueTerminal('.', 'version-separator')) + value = value[1:] + if value and value[0] in CFWS_LEADER: + token, value = get_cfws(value) + mime_version.append(token) + if not value: + if mime_version.major is not None: + mime_version.defects.append(errors.InvalidHeaderDefect( + "Incomplete MIME version; found only major number")) + return mime_version + digits = '' + while value and value[0] not in CFWS_LEADER: + digits += value[0] + value = value[1:] + if not digits.isdigit(): + mime_version.defects.append(errors.InvalidHeaderDefect( + "Expected MIME minor version number but found {!r}".format(digits))) + mime_version.append(ValueTerminal(digits, 'xtext')) + else: + mime_version.minor = int(digits) + mime_version.append(ValueTerminal(digits, 'digits')) + if value and value[0] in CFWS_LEADER: + token, value = get_cfws(value) + mime_version.append(token) + if value: + mime_version.defects.append(errors.InvalidHeaderDefect( + "Excess non-CFWS text after MIME version")) + mime_version.append(ValueTerminal(value, 'xtext')) + return mime_version + +def get_invalid_parameter(value): + """ Read everything up to the next ';'. + + This is outside the formal grammar. The InvalidParameter TokenList that is + returned acts like a Parameter, but the data attributes are None. + + """ + invalid_parameter = InvalidParameter() + while value and value[0] != ';': + if value[0] in PHRASE_ENDS: + invalid_parameter.append(ValueTerminal(value[0], + 'misplaced-special')) + value = value[1:] + else: + token, value = get_phrase(value) + invalid_parameter.append(token) + return invalid_parameter, value + +def get_ttext(value): + """ttext = <matches _ttext_matcher> + + We allow any non-TOKEN_ENDS in ttext, but add defects to the token's + defects list if we find non-ttext characters. We also register defects for + *any* non-printables even though the RFC doesn't exclude all of them, + because we follow the spirit of RFC 5322. + + """ + m = _non_token_end_matcher(value) + if not m: + raise errors.HeaderParseError( + "expected ttext but found '{}'".format(value)) + ttext = m.group() + value = value[len(ttext):] + ttext = ValueTerminal(ttext, 'ttext') + _validate_xtext(ttext) + return ttext, value + +def get_token(value): + """token = [CFWS] 1*ttext [CFWS] + + The RFC equivalent of ttext is any US-ASCII chars except space, ctls, or + tspecials. We also exclude tabs even though the RFC doesn't. + + The RFC implies the CFWS but is not explicit about it in the BNF. + + """ + mtoken = Token() + if value and value[0] in CFWS_LEADER: + token, value = get_cfws(value) + mtoken.append(token) + if value and value[0] in TOKEN_ENDS: + raise errors.HeaderParseError( + "expected token but found '{}'".format(value)) + token, value = get_ttext(value) + mtoken.append(token) + if value and value[0] in CFWS_LEADER: + token, value = get_cfws(value) + mtoken.append(token) + return mtoken, value + +def get_attrtext(value): + """attrtext = 1*(any non-ATTRIBUTE_ENDS character) + + We allow any non-ATTRIBUTE_ENDS in attrtext, but add defects to the + token's defects list if we find non-attrtext characters. We also register + defects for *any* non-printables even though the RFC doesn't exclude all of + them, because we follow the spirit of RFC 5322. + + """ + m = _non_attribute_end_matcher(value) + if not m: + raise errors.HeaderParseError( + "expected attrtext but found {!r}".format(value)) + attrtext = m.group() + value = value[len(attrtext):] + attrtext = ValueTerminal(attrtext, 'attrtext') + _validate_xtext(attrtext) + return attrtext, value + +def get_attribute(value): + """ [CFWS] 1*attrtext [CFWS] + + This version of the BNF makes the CFWS explicit, and as usual we use a + value terminal for the actual run of characters. The RFC equivalent of + attrtext is the token characters, with the subtraction of '*', "'", and '%'. + We include tab in the excluded set just as we do for token. + + """ + attribute = Attribute() + if value and value[0] in CFWS_LEADER: + token, value = get_cfws(value) + attribute.append(token) + if value and value[0] in ATTRIBUTE_ENDS: + raise errors.HeaderParseError( + "expected token but found '{}'".format(value)) + token, value = get_attrtext(value) + attribute.append(token) + if value and value[0] in CFWS_LEADER: + token, value = get_cfws(value) + attribute.append(token) + return attribute, value + +def get_extended_attrtext(value): + """attrtext = 1*(any non-ATTRIBUTE_ENDS character plus '%') + + This is a special parsing routine so that we get a value that + includes % escapes as a single string (which we decode as a single + string later). + + """ + m = _non_extended_attribute_end_matcher(value) + if not m: + raise errors.HeaderParseError( + "expected extended attrtext but found {!r}".format(value)) + attrtext = m.group() + value = value[len(attrtext):] + attrtext = ValueTerminal(attrtext, 'extended-attrtext') + _validate_xtext(attrtext) + return attrtext, value + +def get_extended_attribute(value): + """ [CFWS] 1*extended_attrtext [CFWS] + + This is like the non-extended version except we allow % characters, so that + we can pick up an encoded value as a single string. + + """ + # XXX: should we have an ExtendedAttribute TokenList? + attribute = Attribute() + if value and value[0] in CFWS_LEADER: + token, value = get_cfws(value) + attribute.append(token) + if value and value[0] in EXTENDED_ATTRIBUTE_ENDS: + raise errors.HeaderParseError( + "expected token but found '{}'".format(value)) + token, value = get_extended_attrtext(value) + attribute.append(token) + if value and value[0] in CFWS_LEADER: + token, value = get_cfws(value) + attribute.append(token) + return attribute, value + +def get_section(value): + """ '*' digits + + The formal BNF is more complicated because leading 0s are not allowed. We + check for that and add a defect. We also assume no CFWS is allowed between + the '*' and the digits, though the RFC is not crystal clear on that. + The caller should already have dealt with leading CFWS. + + """ + section = Section() + if not value or value[0] != '*': + raise errors.HeaderParseError("Expected section but found {}".format( + value)) + section.append(ValueTerminal('*', 'section-marker')) + value = value[1:] + if not value or not value[0].isdigit(): + raise errors.HeaderParseError("Expected section number but " + "found {}".format(value)) + digits = '' + while value and value[0].isdigit(): + digits += value[0] + value = value[1:] + if digits[0] == '0' and digits != '0': + section.defects.append(errors.InvalidHeaderError("section number" + "has an invalid leading 0")) + section.number = int(digits) + section.append(ValueTerminal(digits, 'digits')) + return section, value + + +def get_value(value): + """ quoted-string / attribute + + """ + v = Value() + if not value: + raise errors.HeaderParseError("Expected value but found end of string") + leader = None + if value[0] in CFWS_LEADER: + leader, value = get_cfws(value) + if not value: + raise errors.HeaderParseError("Expected value but found " + "only {}".format(leader)) + if value[0] == '"': + token, value = get_quoted_string(value) + else: + token, value = get_extended_attribute(value) + if leader is not None: + token[:0] = [leader] + v.append(token) + return v, value + +def get_parameter(value): + """ attribute [section] ["*"] [CFWS] "=" value + + The CFWS is implied by the RFC but not made explicit in the BNF. This + simplified form of the BNF from the RFC is made to conform with the RFC BNF + through some extra checks. We do it this way because it makes both error + recovery and working with the resulting parse tree easier. + """ + # It is possible CFWS would also be implicitly allowed between the section + # and the 'extended-attribute' marker (the '*') , but we've never seen that + # in the wild and we will therefore ignore the possibility. + param = Parameter() + token, value = get_attribute(value) + param.append(token) + if not value or value[0] == ';': + param.defects.append(errors.InvalidHeaderDefect("Parameter contains " + "name ({}) but no value".format(token))) + return param, value + if value[0] == '*': + try: + token, value = get_section(value) + param.sectioned = True + param.append(token) + except errors.HeaderParseError: + pass + if not value: + raise errors.HeaderParseError("Incomplete parameter") + if value[0] == '*': + param.append(ValueTerminal('*', 'extended-parameter-marker')) + value = value[1:] + param.extended = True + if value[0] != '=': + raise errors.HeaderParseError("Parameter not followed by '='") + param.append(ValueTerminal('=', 'parameter-separator')) + value = value[1:] + leader = None + if value and value[0] in CFWS_LEADER: + token, value = get_cfws(value) + param.append(token) + remainder = None + appendto = param + if param.extended and value and value[0] == '"': + # Now for some serious hackery to handle the common invalid case of + # double quotes around an extended value. We also accept (with defect) + # a value marked as encoded that isn't really. + qstring, remainder = get_quoted_string(value) + inner_value = qstring.stripped_value + semi_valid = False + if param.section_number == 0: + if inner_value and inner_value[0] == "'": + semi_valid = True + else: + token, rest = get_attrtext(inner_value) + if rest and rest[0] == "'": + semi_valid = True + else: + try: + token, rest = get_extended_attrtext(inner_value) + except: + pass + else: + if not rest: + semi_valid = True + if semi_valid: + param.defects.append(errors.InvalidHeaderDefect( + "Quoted string value for extended parameter is invalid")) + param.append(qstring) + for t in qstring: + if t.token_type == 'bare-quoted-string': + t[:] = [] + appendto = t + break + value = inner_value + else: + remainder = None + param.defects.append(errors.InvalidHeaderDefect( + "Parameter marked as extended but appears to have a " + "quoted string value that is non-encoded")) + if value and value[0] == "'": + token = None + else: + token, value = get_value(value) + if not param.extended or param.section_number > 0: + if not value or value[0] != "'": + appendto.append(token) + if remainder is not None: + assert not value, value + value = remainder + return param, value + param.defects.append(errors.InvalidHeaderDefect( + "Apparent initial-extended-value but attribute " + "was not marked as extended or was not initial section")) + if not value: + # Assume the charset/lang is missing and the token is the value. + param.defects.append(errors.InvalidHeaderDefect( + "Missing required charset/lang delimiters")) + appendto.append(token) + if remainder is None: + return param, value + else: + if token is not None: + for t in token: + if t.token_type == 'extended-attrtext': + break + t.token_type == 'attrtext' + appendto.append(t) + param.charset = t.value + if value[0] != "'": + raise errors.HeaderParseError("Expected RFC2231 char/lang encoding " + "delimiter, but found {!r}".format(value)) + appendto.append(ValueTerminal("'", 'RFC2231 delimiter')) + value = value[1:] + if value and value[0] != "'": + token, value = get_attrtext(value) + appendto.append(token) + param.lang = token.value + if not value or value[0] != "'": + raise errors.HeaderParseError("Expected RFC2231 char/lang encoding " + "delimiter, but found {}".format(value)) + appendto.append(ValueTerminal("'", 'RFC2231 delimiter')) + value = value[1:] + if remainder is not None: + # Treat the rest of value as bare quoted string content. + v = Value() + while value: + if value[0] in WSP: + token, value = get_fws(value) + else: + token, value = get_qcontent(value) + v.append(token) + token = v + else: + token, value = get_value(value) + appendto.append(token) + if remainder is not None: + assert not value, value + value = remainder + return param, value + +def parse_mime_parameters(value): + """ parameter *( ";" parameter ) + + That BNF is meant to indicate this routine should only be called after + finding and handling the leading ';'. There is no corresponding rule in + the formal RFC grammar, but it is more convenient for us for the set of + parameters to be treated as its own TokenList. + + This is 'parse' routine because it consumes the reminaing value, but it + would never be called to parse a full header. Instead it is called to + parse everything after the non-parameter value of a specific MIME header. + + """ + mime_parameters = MimeParameters() + while value: + try: + token, value = get_parameter(value) + mime_parameters.append(token) + except errors.HeaderParseError as err: + leader = None + if value[0] in CFWS_LEADER: + leader, value = get_cfws(value) + if not value: + mime_parameters.append(leader) + return mime_parameters + if value[0] == ';': + if leader is not None: + mime_parameters.append(leader) + mime_parameters.defects.append(errors.InvalidHeaderDefect( + "parameter entry with no content")) + else: + token, value = get_invalid_parameter(value) + if leader: + token[:0] = [leader] + mime_parameters.append(token) + mime_parameters.defects.append(errors.InvalidHeaderDefect( + "invalid parameter {!r}".format(token))) + if value and value[0] != ';': + # Junk after the otherwise valid parameter. Mark it as + # invalid, but it will have a value. + param = mime_parameters[-1] + param.token_type = 'invalid-parameter' + token, value = get_invalid_parameter(value) + param.extend(token) + mime_parameters.defects.append(errors.InvalidHeaderDefect( + "parameter with invalid trailing text {!r}".format(token))) + if value: + # Must be a ';' at this point. + mime_parameters.append(ValueTerminal(';', 'parameter-separator')) + value = value[1:] + return mime_parameters + +def _find_mime_parameters(tokenlist, value): + """Do our best to find the parameters in an invalid MIME header + + """ + while value and value[0] != ';': + if value[0] in PHRASE_ENDS: + tokenlist.append(ValueTerminal(value[0], 'misplaced-special')) + value = value[1:] + else: + token, value = get_phrase(value) + tokenlist.append(token) + if not value: + return + tokenlist.append(ValueTerminal(';', 'parameter-separator')) + tokenlist.append(parse_mime_parameters(value[1:])) + +def parse_content_type_header(value): + """ maintype "/" subtype *( ";" parameter ) + + The maintype and substype are tokens. Theoretically they could + be checked against the official IANA list + x-token, but we + don't do that. + """ + ctype = ContentType() + recover = False + if not value: + ctype.defects.append(errors.HeaderMissingRequiredValue( + "Missing content type specification")) + return ctype + try: + token, value = get_token(value) + except errors.HeaderParseError: + ctype.defects.append(errors.InvalidHeaderDefect( + "Expected content maintype but found {!r}".format(value))) + _find_mime_parameters(ctype, value) + return ctype + ctype.append(token) + # XXX: If we really want to follow the formal grammer we should make + # mantype and subtype specialized TokenLists here. Probably not worth it. + if not value or value[0] != '/': + ctype.defects.append(errors.InvalidHeaderDefect( + "Invalid content type")) + if value: + _find_mime_parameters(ctype, value) + return ctype + ctype.maintype = token.value.strip().lower() + ctype.append(ValueTerminal('/', 'content-type-separator')) + value = value[1:] + try: + token, value = get_token(value) + except errors.HeaderParseError: + ctype.defects.append(errors.InvalidHeaderDefect( + "Expected content subtype but found {!r}".format(value))) + _find_mime_parameters(ctype, value) + return ctype + ctype.append(token) + ctype.subtype = token.value.strip().lower() + if not value: + return ctype + if value[0] != ';': + ctype.defects.append(errors.InvalidHeaderDefect( + "Only parameters are valid after content type, but " + "found {!r}".format(value))) + # The RFC requires that a syntactically invalid content-type be treated + # as text/plain. Perhaps we should postel this, but we should probably + # only do that if we were checking the subtype value against IANA. + del ctype.maintype, ctype.subtype + _find_mime_parameters(ctype, value) + return ctype + ctype.append(ValueTerminal(';', 'parameter-separator')) + ctype.append(parse_mime_parameters(value[1:])) + return ctype + +def parse_content_disposition_header(value): + """ disposition-type *( ";" parameter ) + + """ + disp_header = ContentDisposition() + if not value: + disp_header.defects.append(errors.HeaderMissingRequiredValue( + "Missing content disposition")) + return disp_header + try: + token, value = get_token(value) + except errors.HeaderParseError: + ctype.defects.append(errors.InvalidHeaderDefect( + "Expected content disposition but found {!r}".format(value))) + _find_mime_parameters(disp_header, value) + return disp_header + disp_header.append(token) + disp_header.content_disposition = token.value.strip().lower() + if not value: + return disp_header + if value[0] != ';': + disp_header.defects.append(errors.InvalidHeaderDefect( + "Only parameters are valid after content disposition, but " + "found {!r}".format(value))) + _find_mime_parameters(disp_header, value) + return disp_header + disp_header.append(ValueTerminal(';', 'parameter-separator')) + disp_header.append(parse_mime_parameters(value[1:])) + return disp_header + +def parse_content_transfer_encoding_header(value): + """ mechanism + + """ + # We should probably validate the values, since the list is fixed. + cte_header = ContentTransferEncoding() + if not value: + cte_header.defects.append(errors.HeaderMissingRequiredValue( + "Missing content transfer encoding")) + return cte_header + try: + token, value = get_token(value) + except errors.HeaderParseError: + ctype.defects.append(errors.InvalidHeaderDefect( + "Expected content trnasfer encoding but found {!r}".format(value))) + else: + cte_header.append(token) + cte_header.cte = token.value.strip().lower() + if not value: + return cte_header + while value: + cte_header.defects.append(errors.InvalidHeaderDefect( + "Extra text after content transfer encoding")) + if value[0] in PHRASE_ENDS: + cte_header.append(ValueTerminal(value[0], 'misplaced-special')) + value = value[1:] + else: + token, value = get_phrase(value) + cte_header.append(token) + return cte_header |