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 "net/http/http_util.h"
  18 #include "url/gurl.h"
  19
  20 namespace net {
  21
  22 // static
  23 bool DataURL::Parse(const GURL& url, std::string* mime_type,
  24                     std::string* charset, std::string* data) {
  25   DCHECK(mime_type->empty());
  26   DCHECK(charset->empty());
  27   std::string::const_iterator begin = url.spec().begin();
  28   std::string::const_iterator end = url.spec().end();
  29
  30   std::string::const_iterator after_colon = std::find(begin, end, ':');
  31   if (after_colon == end)
  32     return false;
  33   ++after_colon;
  34
  35   std::string::const_iterator comma = std::find(after_colon, end, ',');
  36   if (comma == end)
  37     return false;
  38
  39   std::vector<std::string> meta_data;
  40   std::string unparsed_meta_data(after_colon, comma);
  41   base::SplitString(unparsed_meta_data, ';', &meta_data);
  42
  43   std::vector<std::string>::iterator iter = meta_data.begin();
  44   if (iter != meta_data.end()) {
  45     mime_type->swap(*iter);
  46     base::StringToLowerASCII(mime_type);
  47     ++iter;
  48   }
  49
  50   static const char kBase64Tag[] = "base64";
  51   static const char kCharsetTag[] = "charset=";
  52   const size_t kCharsetTagLength = arraysize(kCharsetTag) - 1;
  53
  54   bool base64_encoded = false;
  55   for (; iter != meta_data.end(); ++iter) {
  56     if (!base64_encoded && *iter == kBase64Tag) {
  57       base64_encoded = true;
  58     } else if (charset->empty() &&
  59                iter->compare(0, kCharsetTagLength, kCharsetTag) == 0) {
  60       charset->assign(iter->substr(kCharsetTagLength));
  61       // The grammar for charset is not specially defined in RFC2045 and
  62       // RFC2397. It just needs to be a token.
  63       if (!net::HttpUtil::IsToken(*charset))
  64         return false;
  65     }
  66   }
  67
  68   if (mime_type->empty()) {
  69     // fallback to defaults if nothing specified in the URL:
  70     mime_type->assign("text/plain");
  71   } else if (!ParseMimeTypeWithoutParameter(*mime_type, NULL, NULL)) {
  72     return false;
  73   }
  74   if (charset->empty())
  75     charset->assign("US-ASCII");
  76
  77   // The caller may not be interested in receiving the data.
  78   if (!data)
  79     return true;
  80
  81   // Preserve spaces if dealing with text or xml input, same as mozilla:
  82   //   https://bugzilla.mozilla.org/show_bug.cgi?id=138052
  83   // but strip them otherwise:
  84   //   https://bugzilla.mozilla.org/show_bug.cgi?id=37200
  85   // (Spaces in a data URL should be escaped, which is handled below, so any
  86   // spaces now are wrong. People expect to be able to enter them in the URL
  87   // bar for text, and it can't hurt, so we allow it.)
  88   std::string temp_data = std::string(comma + 1, end);
  89
  90   // For base64, we may have url-escaped whitespace which is not part
  91   // of the data, and should be stripped. Otherwise, the escaped whitespace
  92   // could be part of the payload, so don't strip it.
  93   if (base64_encoded) {
  94     temp_data = UnescapeURLComponent(temp_data,
  95         UnescapeRule::SPACES | UnescapeRule::URL_SPECIAL_CHARS |
  96         UnescapeRule::CONTROL_CHARS);
  97   }
  98
  99   // Strip whitespace.
 100   if (base64_encoded || !(mime_type->compare(0, 5, "text/") == 0 ||
 101                           mime_type->find("xml") != std::string::npos)) {
 102     temp_data.erase(std::remove_if(temp_data.begin(), temp_data.end(),
 103                                    IsAsciiWhitespace<wchar_t>),
 104                     temp_data.end());
 105   }
 106
 107   if (!base64_encoded) {
 108     temp_data = UnescapeURLComponent(temp_data,
 109         UnescapeRule::SPACES | UnescapeRule::URL_SPECIAL_CHARS |
 110         UnescapeRule::CONTROL_CHARS);
 111   }
 112
 113   if (base64_encoded) {
 114     size_t length = temp_data.length();
 115     size_t padding_needed = 4 - (length % 4);
 116     // If the input wasn't padded, then we pad it as necessary until we have a
 117     // length that is a multiple of 4 as required by our decoder. We don't
 118     // correct if the input was incorrectly padded. If |padding_needed| == 3,
 119     // then the input isn't well formed and decoding will fail with or without
 120     // padding.
 121     if ((padding_needed == 1 || padding_needed == 2) &&
 122         temp_data[length - 1] != '=') {
 123       temp_data.resize(length + padding_needed, '=');
 124     }
 125     return base::Base64Decode(temp_data, data);
 126   }
 127
 128   temp_data.swap(*data);
 129   return true;
 130 }
 131
 132 }  // namespace net