// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "net/http/http_content_disposition.h"
#include "base/base64.h"
#include "base/logging.h"
#include "base/strings/string_tokenizer.h"
#include "base/strings/string_util.h"
#include "base/strings/sys_string_conversions.h"
#include "base/strings/utf_string_conversions.h"
#include "net/base/net_string_util.h"
#include "net/base/net_util.h"
#include "net/http/http_util.h"
namespace {
enum RFC2047EncodingType {
Q_ENCODING,
B_ENCODING
};
// Decodes a "Q" encoded string as described in RFC 2047 section 4.2. Similar to
// decoding a quoted-printable string. Returns true if the input was valid.
bool DecodeQEncoding(const std::string& input, std::string* output) {
std::string temp;
temp.reserve(input.size());
for (std::string::const_iterator it = input.begin(); it != input.end();
++it) {
if (*it == '_') {
temp.push_back(' ');
} else if (*it == '=') {
if ((input.end() - it < 3) ||
!IsHexDigit(static_cast<unsigned char>(*(it + 1))) ||
!IsHexDigit(static_cast<unsigned char>(*(it + 2))))
return false;
unsigned char ch = HexDigitToInt(*(it + 1)) * 16 +
HexDigitToInt(*(it + 2));
temp.push_back(static_cast<char>(ch));
++it;
++it;
} else if (0x20 < *it && *it < 0x7F && *it != '?') {
// In a Q-encoded word, only printable ASCII characters
// represent themselves. Besides, space, '=', '_' and '?' are
// not allowed, but they're already filtered out.
DCHECK_NE('=', *it);
DCHECK_NE('?', *it);
DCHECK_NE('_', *it);
temp.push_back(*it);
} else {
return false;
}
}
output->swap(temp);
return true;
}
// Decodes a "Q" or "B" encoded string as per RFC 2047 section 4. The encoding
// type is specified in |enc_type|.
bool DecodeBQEncoding(const std::string& part,
RFC2047EncodingType enc_type,
const std::string& charset,
std::string* output) {
std::string decoded;
if (!((enc_type == B_ENCODING) ?
base::Base64Decode(part, &decoded) : DecodeQEncoding(part, &decoded))) {
return false;
}
if (decoded.empty()) {
output->clear();
return true;
}
return net::ConvertToUtf8(decoded, charset.c_str(), output);
}
bool DecodeWord(const std::string& encoded_word,
const std::string& referrer_charset,
bool* is_rfc2047,
std::string* output,
int* parse_result_flags) {
*is_rfc2047 = false;
output->clear();
if (encoded_word.empty())
return true;
if (!base::IsStringASCII(encoded_word)) {
// Try UTF-8, referrer_charset and the native OS default charset in turn.
if (base::IsStringUTF8(encoded_word)) {
*output = encoded_word;
} else {
base::string16 utf16_output;
if (!referrer_charset.empty() &&
net::ConvertToUTF16(encoded_word, referrer_charset.c_str(),
&utf16_output)) {
*output = base::UTF16ToUTF8(utf16_output);
} else {
*output = base::WideToUTF8(base::SysNativeMBToWide(encoded_word));
}
}
*parse_result_flags |= net::HttpContentDisposition::HAS_NON_ASCII_STRINGS;
return true;
}
// RFC 2047 : one of encoding methods supported by Firefox and relatively
// widely used by web servers.
// =?charset?<E>?<encoded string>?= where '<E>' is either 'B' or 'Q'.
// We don't care about the length restriction (72 bytes) because
// many web servers generate encoded words longer than the limit.
std::string decoded_word;
*is_rfc2047 = true;
int part_index = 0;
std::string charset;
base::StringTokenizer t(encoded_word, "?");
RFC2047EncodingType enc_type = Q_ENCODING;
while (*is_rfc2047 && t.GetNext()) {
std::string part = t.token();
switch (part_index) {
case 0:
if (part != "=") {
*is_rfc2047 = false;
break;
}
++part_index;
break;
case 1:
// Do we need charset validity check here?
charset = part;
++part_index;
break;
case 2:
if (part.size() > 1 ||
part.find_first_of("bBqQ") == std::string::npos) {
*is_rfc2047 = false;
break;
}
if (part[0] == 'b' || part[0] == 'B') {
enc_type = B_ENCODING;
}
++part_index;
break;
case 3:
*is_rfc2047 = DecodeBQEncoding(part, enc_type, charset, &decoded_word);
if (!*is_rfc2047) {
// Last minute failure. Invalid B/Q encoding. Rather than
// passing it through, return now.
return false;
}
++part_index;
break;
case 4:
if (part != "=") {
// Another last minute failure !
// Likely to be a case of two encoded-words in a row or
// an encoded word followed by a non-encoded word. We can be
// generous, but it does not help much in terms of compatibility,
// I believe. Return immediately.
*is_rfc2047 = false;
return false;
}
++part_index;
break;
default:
*is_rfc2047 = false;
return false;
}
}
if (*is_rfc2047) {
if (*(encoded_word.end() - 1) == '=') {
output->swap(decoded_word);
*parse_result_flags |=
net::HttpContentDisposition::HAS_RFC2047_ENCODED_STRINGS;
return true;
}
// encoded_word ending prematurelly with '?' or extra '?'
*is_rfc2047 = false;
return false;
}
// We're not handling 'especial' characters quoted with '\', but
// it should be Ok because we're not an email client but a
// web browser.
// What IE6/7 does: %-escaped UTF-8.
decoded_word = net::UnescapeURLComponent(encoded_word,
net::UnescapeRule::SPACES);
if (decoded_word != encoded_word)
*parse_result_flags |=
net::HttpContentDisposition::HAS_PERCENT_ENCODED_STRINGS;
if (base::IsStringUTF8(decoded_word)) {
output->swap(decoded_word);
return true;
// We can try either the OS default charset or 'origin charset' here,
// As far as I can tell, IE does not support it. However, I've seen
// web servers emit %-escaped string in a legacy encoding (usually
// origin charset).
// TODO(jungshik) : Test IE further and consider adding a fallback here.
}
return false;
}
// Decodes the value of a 'filename' or 'name' parameter given as |input|. The
// value is supposed to be of the form:
//
// value = token | quoted-string
//
// However we currently also allow RFC 2047 encoding and non-ASCII
// strings. Non-ASCII strings are interpreted based on |referrer_charset|.
bool DecodeFilenameValue(const std::string& input,
const std::string& referrer_charset,
std::string* output,
int* parse_result_flags) {
int current_parse_result_flags = 0;
std::string decoded_value;
bool is_previous_token_rfc2047 = true;
// Tokenize with whitespace characters.
base::StringTokenizer t(input, " \t\n\r");
t.set_options(base::StringTokenizer::RETURN_DELIMS);
while (t.GetNext()) {
if (t.token_is_delim()) {
// If the previous non-delimeter token is not RFC2047-encoded,
// put in a space in its place. Otheriwse, skip over it.
if (!is_previous_token_rfc2047)
decoded_value.push_back(' ');
continue;
}
// We don't support a single multibyte character split into
// adjacent encoded words. Some broken mail clients emit headers
// with that problem, but most web servers usually encode a filename
// in a single encoded-word. Firefox/Thunderbird do not support
// it, either.
std::string decoded;
if (!DecodeWord(t.token(), referrer_charset, &is_previous_token_rfc2047,
&decoded, ¤t_parse_result_flags))
return false;
decoded_value.append(decoded);
}
output->swap(decoded_value);
if (parse_result_flags && !output->empty())
*parse_result_flags |= current_parse_result_flags;
return true;
}
// Parses the charset and value-chars out of an ext-value string.
//
// ext-value = charset "'" [ language ] "'" value-chars
bool ParseExtValueComponents(const std::string& input,
std::string* charset,
std::string* value_chars) {
base::StringTokenizer t(input, "'");
t.set_options(base::StringTokenizer::RETURN_DELIMS);
std::string temp_charset;
std::string temp_value;
int numDelimsSeen = 0;
while (t.GetNext()) {
if (t.token_is_delim()) {
++numDelimsSeen;
continue;
} else {
switch (numDelimsSeen) {
case 0:
temp_charset = t.token();
break;
case 1:
// Language is ignored.
break;
case 2:
temp_value = t.token();
break;
default:
return false;
}
}
}
if (numDelimsSeen != 2)
return false;
if (temp_charset.empty() || temp_value.empty())
return false;
charset->swap(temp_charset);
value_chars->swap(temp_value);
return true;
}
// http://tools.ietf.org/html/rfc5987#section-3.2
//
// ext-value = charset "'" [ language ] "'" value-chars
//
// charset = "UTF-8" / "ISO-8859-1" / mime-charset
//
// mime-charset = 1*mime-charsetc
// mime-charsetc = ALPHA / DIGIT
// / "!" / "#" / "$" / "%" / "&"
// / "+" / "-" / "^" / "_" / "`"
// / "{" / "}" / "~"
//
// language = <Language-Tag, defined in [RFC5646], Section 2.1>
//
// value-chars = *( pct-encoded / attr-char )
//
// pct-encoded = "%" HEXDIG HEXDIG
//
// attr-char = ALPHA / DIGIT
// / "!" / "#" / "$" / "&" / "+" / "-" / "."
// / "^" / "_" / "`" / "|" / "~"
bool DecodeExtValue(const std::string& param_value, std::string* decoded) {
if (param_value.find('"') != std::string::npos)
return false;
std::string charset;
std::string value;
if (!ParseExtValueComponents(param_value, &charset, &value))
return false;
// RFC 5987 value should be ASCII-only.
if (!base::IsStringASCII(value)) {
decoded->clear();
return true;
}
std::string unescaped = net::UnescapeURLComponent(
value, net::UnescapeRule::SPACES | net::UnescapeRule::URL_SPECIAL_CHARS);
return net::ConvertToUtf8AndNormalize(unescaped, charset.c_str(), decoded);
}
} // namespace
namespace net {
HttpContentDisposition::HttpContentDisposition(
const std::string& header, const std::string& referrer_charset)
: type_(INLINE),
parse_result_flags_(INVALID) {
Parse(header, referrer_charset);
}
HttpContentDisposition::~HttpContentDisposition() {
}
std::string::const_iterator HttpContentDisposition::ConsumeDispositionType(
std::string::const_iterator begin, std::string::const_iterator end) {
DCHECK(type_ == INLINE);
std::string::const_iterator delimiter = std::find(begin, end, ';');
std::string::const_iterator type_begin = begin;
std::string::const_iterator type_end = delimiter;
HttpUtil::TrimLWS(&type_begin, &type_end);
// If the disposition-type isn't a valid token the then the
// Content-Disposition header is malformed, and we treat the first bytes as
// a parameter rather than a disposition-type.
if (!HttpUtil::IsToken(type_begin, type_end))
return begin;
parse_result_flags_ |= HAS_DISPOSITION_TYPE;
DCHECK(std::find(type_begin, type_end, '=') == type_end);
if (LowerCaseEqualsASCII(type_begin, type_end, "inline")) {
type_ = INLINE;
} else if (LowerCaseEqualsASCII(type_begin, type_end, "attachment")) {
type_ = ATTACHMENT;
} else {
parse_result_flags_ |= HAS_UNKNOWN_DISPOSITION_TYPE;
type_ = ATTACHMENT;
}
return delimiter;
}
// http://tools.ietf.org/html/rfc6266
//
// content-disposition = "Content-Disposition" ":"
// disposition-type *( ";" disposition-parm )
//
// disposition-type = "inline" | "attachment" | disp-ext-type
// ; case-insensitive
// disp-ext-type = token
//
// disposition-parm = filename-parm | disp-ext-parm
//
// filename-parm = "filename" "=" value
// | "filename*" "=" ext-value
//
// disp-ext-parm = token "=" value
// | ext-token "=" ext-value
// ext-token = <the characters in token, followed by "*">
//
void HttpContentDisposition::Parse(const std::string& header,
const std::string& referrer_charset) {
DCHECK(type_ == INLINE);
DCHECK(filename_.empty());
std::string::const_iterator pos = header.begin();
std::string::const_iterator end = header.end();
pos = ConsumeDispositionType(pos, end);
std::string name;
std::string filename;
std::string ext_filename;
HttpUtil::NameValuePairsIterator iter(pos, end, ';');
while (iter.GetNext()) {
if (filename.empty() && LowerCaseEqualsASCII(iter.name_begin(),
iter.name_end(),
"filename")) {
DecodeFilenameValue(iter.value(), referrer_charset, &filename,
&parse_result_flags_);
if (!filename.empty())
parse_result_flags_ |= HAS_FILENAME;
} else if (name.empty() && LowerCaseEqualsASCII(iter.name_begin(),
iter.name_end(),
"name")) {
DecodeFilenameValue(iter.value(), referrer_charset, &name, NULL);
if (!name.empty())
parse_result_flags_ |= HAS_NAME;
} else if (ext_filename.empty() && LowerCaseEqualsASCII(iter.name_begin(),
iter.name_end(),
"filename*")) {
DecodeExtValue(iter.raw_value(), &ext_filename);
if (!ext_filename.empty())
parse_result_flags_ |= HAS_EXT_FILENAME;
}
}
if (!ext_filename.empty())
filename_ = ext_filename;
else if (!filename.empty())
filename_ = filename;
else
filename_ = name;
}
} // namespace net