components/crx_file/id_util.cc

   1 // Copyright 2014 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 "components/crx_file/id_util.h"
   6
   7 #include "base/files/file_path.h"
   8 #include "base/strings/string_number_conversions.h"
   9 #include "base/strings/string_util.h"
  10 #include "crypto/sha2.h"
  11
  12 namespace {
  13
  14 // Converts a normal hexadecimal string into the alphabet used by extensions.
  15 // We use the characters 'a'-'p' instead of '0'-'f' to avoid ever having a
  16 // completely numeric host, since some software interprets that as an IP
  17 // address.
  18 static void ConvertHexadecimalToIDAlphabet(std::string* id) {
  19   for (size_t i = 0; i < id->size(); ++i) {
  20     int val;
  21     if (base::HexStringToInt(
  22             base::StringPiece(id->begin() + i, id->begin() + i + 1), &val)) {
  23       (*id)[i] = val + 'a';
  24     } else {
  25       (*id)[i] = 'a';
  26     }
  27   }
  28 }
  29
  30 }  // namespace
  31
  32 namespace crx_file {
  33 namespace id_util {
  34
  35 // First 16 bytes of SHA256 hashed public key.
  36 const size_t kIdSize = 16;
  37
  38 std::string GenerateId(const std::string& input) {
  39   uint8 hash[kIdSize];
  40   crypto::SHA256HashString(input, hash, sizeof(hash));
  41   std::string output =
  42       base::StringToLowerASCII(base::HexEncode(hash, sizeof(hash)));
  43   ConvertHexadecimalToIDAlphabet(&output);
  44
  45   return output;
  46 }
  47
  48 std::string GenerateIdForPath(const base::FilePath& path) {
  49   base::FilePath new_path = MaybeNormalizePath(path);
  50   std::string path_bytes =
  51       std::string(reinterpret_cast<const char*>(new_path.value().data()),
  52                   new_path.value().size() * sizeof(base::FilePath::CharType));
  53   return GenerateId(path_bytes);
  54 }
  55
  56 base::FilePath MaybeNormalizePath(const base::FilePath& path) {
  57 #if defined(OS_WIN)
  58   // Normalize any drive letter to upper-case. We do this for consistency with
  59   // net_utils::FilePathToFileURL(), which does the same thing, to make string
  60   // comparisons simpler.
  61   base::FilePath::StringType path_str = path.value();
  62   if (path_str.size() >= 2 && path_str[0] >= L'a' && path_str[0] <= L'z' &&
  63       path_str[1] == L':')
  64     path_str[0] = towupper(path_str[0]);
  65
  66   return base::FilePath(path_str);
  67 #else
  68   return path;
  69 #endif
  70 }
  71
  72 bool IdIsValid(const std::string& id) {
  73   // Verify that the id is legal.
  74   if (id.size() != (crx_file::id_util::kIdSize * 2))
  75     return false;
  76
  77   // We only support lowercase IDs, because IDs can be used as URL components
  78   // (where GURL will lowercase it).
  79   std::string temp = base::StringToLowerASCII(id);
  80   for (size_t i = 0; i < temp.size(); i++)
  81     if (temp[i] < 'a' || temp[i] > 'p')
  82       return false;
  83
  84   return true;
  85 }
  86
  87 }  // namespace id_util
  88 }  // namespace crx_file