net/base/data_url.cc

   1 // Copyright (c) 2012 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 // NOTE: based loosely on mozilla's nsDataChannel.cpp
   6
   7 #include <algorithm>
   8
   9 #include "net/base/data_url.h"
  10
  11 #include "base/base64.h"
  12 #include "base/basictypes.h"
  13 #include "base/strings/string_split.h"
  14 #include "base/strings/string_util.h"
  15 #include "net/base/escape.h"
  16 #include "net/base/mime_util.h"
  17 #include "url/gurl.h"
  18
  19 namespace net {
  20
  21 // static
  22 bool DataURL::Parse(const GURL& url, std::string* mime_type,
  23                     std::string* charset, std::string* data) {
  24   DCHECK(mime_type->empty());
  25   DCHECK(charset->empty());
  26   std::string::const_iterator begin = url.spec().begin();
  27   std::string::const_iterator end = url.spec().end();
  28
  29   std::string::const_iterator after_colon = std::find(begin, end, ':');
  30   if (after_colon == end)
  31     return false;
  32   ++after_colon;
  33
  34   std::string::const_iterator comma = std::find(after_colon, end, ',');
  35   if (comma == end)
  36     return false;
  37
  38   std::vector<std::string> meta_data;
  39   std::string unparsed_meta_data(after_colon, comma);
  40   base::SplitString(unparsed_meta_data, ';', &meta_data);
  41
  42   std::vector<std::string>::iterator iter = meta_data.begin();
  43   if (iter != meta_data.end()) {
  44     mime_type->swap(*iter);
  45     StringToLowerASCII(mime_type);
  46     ++iter;
  47   }
  48
  49   static const char kBase64Tag[] = "base64";
  50   static const char kCharsetTag[] = "charset=";
  51   const size_t kCharsetTagLength = arraysize(kCharsetTag) - 1;
  52
  53   bool base64_encoded = false;
  54   for (; iter != meta_data.end(); ++iter) {
  55     if (!base64_encoded && *iter == kBase64Tag) {
  56       base64_encoded = true;
  57     } else if (charset->empty() &&
  58                iter->compare(0, kCharsetTagLength, kCharsetTag) == 0) {
  59       charset->assign(iter->substr(kCharsetTagLength));
  60     }
  61   }
  62
  63   if (mime_type->empty()) {
  64     // fallback to defaults if nothing specified in the URL:
  65     mime_type->assign("text/plain");
  66   } else if (!ParseMimeTypeWithoutParameter(*mime_type, NULL, NULL)) {
  67     return false;
  68   }
  69   if (charset->empty())
  70     charset->assign("US-ASCII");
  71
  72   // The caller may not be interested in receiving the data.
  73   if (!data)
  74     return true;
  75
  76   // Preserve spaces if dealing with text or xml input, same as mozilla:
  77   //   https://bugzilla.mozilla.org/show_bug.cgi?id=138052
  78   // but strip them otherwise:
  79   //   https://bugzilla.mozilla.org/show_bug.cgi?id=37200
  80   // (Spaces in a data URL should be escaped, which is handled below, so any
  81   // spaces now are wrong. People expect to be able to enter them in the URL
  82   // bar for text, and it can't hurt, so we allow it.)
  83   std::string temp_data = std::string(comma + 1, end);
  84
  85   // For base64, we may have url-escaped whitespace which is not part
  86   // of the data, and should be stripped. Otherwise, the escaped whitespace
  87   // could be part of the payload, so don't strip it.
  88   if (base64_encoded) {
  89     temp_data = UnescapeURLComponent(temp_data,
  90         UnescapeRule::SPACES | UnescapeRule::URL_SPECIAL_CHARS |
  91         UnescapeRule::CONTROL_CHARS);
  92   }
  93
  94   // Strip whitespace.
  95   if (base64_encoded || !(mime_type->compare(0, 5, "text/") == 0 ||
  96                           mime_type->find("xml") != std::string::npos)) {
  97     temp_data.erase(std::remove_if(temp_data.begin(), temp_data.end(),
  98                                    IsAsciiWhitespace<wchar_t>),
  99                     temp_data.end());
 100   }
 101
 102   if (!base64_encoded) {
 103     temp_data = UnescapeURLComponent(temp_data,
 104         UnescapeRule::SPACES | UnescapeRule::URL_SPECIAL_CHARS |
 105         UnescapeRule::CONTROL_CHARS);
 106   }
 107
 108   if (base64_encoded) {
 109     size_t length = temp_data.length();
 110     size_t padding_needed = 4 - (length % 4);
 111     // If the input wasn't padded, then we pad it as necessary until we have a
 112     // length that is a multiple of 4 as required by our decoder. We don't
 113     // correct if the input was incorrectly padded. If |padding_needed| == 3,
 114     // then the input isn't well formed and decoding will fail with or without
 115     // padding.
 116     if ((padding_needed == 1 || padding_needed == 2) &&
 117         temp_data[length - 1] != '=') {
 118       temp_data.resize(length + padding_needed, '=');
 119     }
 120     return base::Base64Decode(temp_data, data);
 121   }
 122
 123   temp_data.swap(*data);
 124   return true;
 125 }
 126
 127 }  // namespace net