url/url_canon_query.cc

   1 // Copyright 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "url/url_canon.h"
   6 #include "url/url_canon_internal.h"
   7
   8 // Query canonicalization in IE
   9 // ----------------------------
  10 // IE is very permissive for query parameters specified in links on the page
  11 // (in contrast to links that it constructs itself based on form data). It does
  12 // not unescape any character. It does not reject any escape sequence (be they
  13 // invalid like "%2y" or freaky like %00).
  14 //
  15 // IE only escapes spaces and nothing else. Embedded NULLs, tabs (0x09),
  16 // LF (0x0a), and CR (0x0d) are removed (this probably happens at an earlier
  17 // layer since they are removed from all portions of the URL). All other
  18 // characters are passed unmodified. Invalid UTF-16 sequences are preserved as
  19 // well, with each character in the input being converted to UTF-8. It is the
  20 // server's job to make sense of this invalid query.
  21 //
  22 // Invalid multibyte sequences (for example, invalid UTF-8 on a UTF-8 page)
  23 // are converted to the invalid character and sent as unescaped UTF-8 (0xef,
  24 // 0xbf, 0xbd). This may not be canonicalization, the parser may generate these
  25 // strings before the URL handler ever sees them.
  26 //
  27 // Our query canonicalization
  28 // --------------------------
  29 // We escape all non-ASCII characters and control characters, like Firefox.
  30 // This is more conformant to the URL spec, and there do not seem to be many
  31 // problems relating to Firefox's behavior.
  32 //
  33 // Like IE, we will never unescape (although the application may want to try
  34 // unescaping to present the user with a more understandable URL). We will
  35 // replace all invalid sequences (including invalid UTF-16 sequences, which IE
  36 // doesn't) with the "invalid character," and we will escape it.
  37
  38 namespace url {
  39
  40 namespace {
  41
  42 // Returns true if the characters starting at |begin| and going until |end|
  43 // (non-inclusive) are all representable in 7-bits.
  44 template<typename CHAR, typename UCHAR>
  45 bool IsAllASCII(const CHAR* spec, const Component& query) {
  46   int end = query.end();
  47   for (int i = query.begin; i < end; i++) {
  48     if (static_cast<UCHAR>(spec[i]) >= 0x80)
  49       return false;
  50   }
  51   return true;
  52 }
  53
  54 // Appends the given string to the output, escaping characters that do not
  55 // match the given |type| in SharedCharTypes. This version will accept 8 or 16
  56 // bit characters, but assumes that they have only 7-bit values. It also assumes
  57 // that all UTF-8 values are correct, so doesn't bother checking
  58 template<typename CHAR>
  59 void AppendRaw8BitQueryString(const CHAR* source, int length,
  60                               CanonOutput* output) {
  61   for (int i = 0; i < length; i++) {
  62     if (!IsQueryChar(static_cast<unsigned char>(source[i])))
  63       AppendEscapedChar(static_cast<unsigned char>(source[i]), output);
  64     else  // Doesn't need escaping.
  65       output->push_back(static_cast<char>(source[i]));
  66   }
  67 }
  68
  69 // Runs the converter on the given UTF-8 input. Since the converter expects
  70 // UTF-16, we have to convert first. The converter must be non-NULL.
  71 void RunConverter(const char* spec,
  72                   const Component& query,
  73                   CharsetConverter* converter,
  74                   CanonOutput* output) {
  75   // This function will replace any misencoded values with the invalid
  76   // character. This is what we want so we don't have to check for error.
  77   RawCanonOutputW<1024> utf16;
  78   ConvertUTF8ToUTF16(&spec[query.begin], query.len, &utf16);
  79   converter->ConvertFromUTF16(utf16.data(), utf16.length(), output);
  80 }
  81
  82 // Runs the converter with the given UTF-16 input. We don't have to do
  83 // anything, but this overriddden function allows us to use the same code
  84 // for both UTF-8 and UTF-16 input.
  85 void RunConverter(const base::char16* spec,
  86                   const Component& query,
  87                   CharsetConverter* converter,
  88                   CanonOutput* output) {
  89   converter->ConvertFromUTF16(&spec[query.begin], query.len, output);
  90 }
  91
  92 template<typename CHAR, typename UCHAR>
  93 void DoConvertToQueryEncoding(const CHAR* spec,
  94                               const Component& query,
  95                               CharsetConverter* converter,
  96                               CanonOutput* output) {
  97   if (IsAllASCII<CHAR, UCHAR>(spec, query)) {
  98     // Easy: the input can just appended with no character set conversions.
  99     AppendRaw8BitQueryString(&spec[query.begin], query.len, output);
 100
 101   } else {
 102     // Harder: convert to the proper encoding first.
 103     if (converter) {
 104       // Run the converter to get an 8-bit string, then append it, escaping
 105       // necessary values.
 106       RawCanonOutput<1024> eight_bit;
 107       RunConverter(spec, query, converter, &eight_bit);
 108       AppendRaw8BitQueryString(eight_bit.data(), eight_bit.length(), output);
 109
 110     } else {
 111       // No converter, do our own UTF-8 conversion.
 112       AppendStringOfType(&spec[query.begin], query.len, CHAR_QUERY, output);
 113     }
 114   }
 115 }
 116
 117 template<typename CHAR, typename UCHAR>
 118 void DoCanonicalizeQuery(const CHAR* spec,
 119                          const Component& query,
 120                          CharsetConverter* converter,
 121                          CanonOutput* output,
 122                          Component* out_query) {
 123   if (query.len < 0) {
 124     *out_query = Component();
 125     return;
 126   }
 127
 128   output->push_back('?');
 129   out_query->begin = output->length();
 130
 131   DoConvertToQueryEncoding<CHAR, UCHAR>(spec, query, converter, output);
 132
 133   out_query->len = output->length() - out_query->begin;
 134 }
 135
 136 }  // namespace
 137
 138 void CanonicalizeQuery(const char* spec,
 139                        const Component& query,
 140                        CharsetConverter* converter,
 141                        CanonOutput* output,
 142                        Component* out_query) {
 143   DoCanonicalizeQuery<char, unsigned char>(spec, query, converter,
 144                                            output, out_query);
 145 }
 146
 147 void CanonicalizeQuery(const base::char16* spec,
 148                        const Component& query,
 149                        CharsetConverter* converter,
 150                        CanonOutput* output,
 151                        Component* out_query) {
 152   DoCanonicalizeQuery<base::char16, base::char16>(spec, query, converter,
 153                                                   output, out_query);
 154 }
 155
 156 void ConvertUTF16ToQueryEncoding(const base::char16* input,
 157                                  const Component& query,
 158                                  CharsetConverter* converter,
 159                                  CanonOutput* output) {
 160   DoConvertToQueryEncoding<base::char16, base::char16>(input, query,
 161                                                        converter, output);
 162 }
 163
 164 }  // namespace url