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/sha1.h"
   9 #include "base/strings/string_number_conversions.h"
  10 #include "base/strings/string_util.h"
  11 #include "crypto/sha2.h"
  12
  13 namespace {
  14
  15 // Converts a normal hexadecimal string into the alphabet used by extensions.
  16 // We use the characters 'a'-'p' instead of '0'-'f' to avoid ever having a
  17 // completely numeric host, since some software interprets that as an IP
  18 // address.
  19 static void ConvertHexadecimalToIDAlphabet(std::string* id) {
  20   for (size_t i = 0; i < id->size(); ++i) {
  21     int val;
  22     if (base::HexStringToInt(
  23             base::StringPiece(id->begin() + i, id->begin() + i + 1), &val)) {
  24       (*id)[i] = val + 'a';
  25     } else {
  26       (*id)[i] = 'a';
  27     }
  28   }
  29 }
  30
  31 }  // namespace
  32
  33 namespace crx_file {
  34 namespace id_util {
  35
  36 // First 16 bytes of SHA256 hashed public key.
  37 const size_t kIdSize = 16;
  38
  39 std::string GenerateId(const std::string& input) {
  40   uint8 hash[kIdSize];
  41   crypto::SHA256HashString(input, hash, sizeof(hash));
  42   std::string output =
  43       base::ToLowerASCII(base::HexEncode(hash, sizeof(hash)));
  44   ConvertHexadecimalToIDAlphabet(&output);
  45
  46   return output;
  47 }
  48
  49 std::string GenerateIdForPath(const base::FilePath& path) {
  50   base::FilePath new_path = MaybeNormalizePath(path);
  51   std::string path_bytes =
  52       std::string(reinterpret_cast<const char*>(new_path.value().data()),
  53                   new_path.value().size() * sizeof(base::FilePath::CharType));
  54   return GenerateId(path_bytes);
  55 }
  56
  57 std::string HashedIdInHex(const std::string& id) {
  58   const std::string id_hash = base::SHA1HashString(id);
  59   DCHECK_EQ(base::kSHA1Length, id_hash.length());
  60   return base::HexEncode(id_hash.c_str(), id_hash.length());
  61 }
  62
  63 base::FilePath MaybeNormalizePath(const base::FilePath& path) {
  64 #if defined(OS_WIN)
  65   // Normalize any drive letter to upper-case. We do this for consistency with
  66   // net_utils::FilePathToFileURL(), which does the same thing, to make string
  67   // comparisons simpler.
  68   base::FilePath::StringType path_str = path.value();
  69   if (path_str.size() >= 2 && path_str[0] >= L'a' && path_str[0] <= L'z' &&
  70       path_str[1] == L':')
  71     path_str[0] = towupper(path_str[0]);
  72
  73   return base::FilePath(path_str);
  74 #else
  75   return path;
  76 #endif
  77 }
  78
  79 bool IdIsValid(const std::string& id) {
  80   // Verify that the id is legal.
  81   if (id.size() != (crx_file::id_util::kIdSize * 2))
  82     return false;
  83
  84   // We only support lowercase IDs, because IDs can be used as URL components
  85   // (where GURL will lowercase it).
  86   std::string temp = base::ToLowerASCII(id);
  87   for (size_t i = 0; i < temp.size(); i++)
  88     if (temp[i] < 'a' || temp[i] > 'p')
  89       return false;
  90
  91   return true;
  92 }
  93
  94 }  // namespace id_util
  95 }  // namespace crx_file