/*
 * Copyright (C) 2018 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "veridex.h"

#include <android-base/file.h>

#include "dex/dex_file.h"
#include "dex/dex_file_loader.h"
#include "hidden_api.h"
#include "hidden_api_finder.h"
#include "precise_hidden_api_finder.h"
#include "resolver.h"

#include <cstdlib>
#include <sstream>

namespace art {

static VeriClass z_(Primitive::Type::kPrimBoolean, 0, nullptr);
static VeriClass b_(Primitive::Type::kPrimByte, 0, nullptr);
static VeriClass c_(Primitive::Type::kPrimChar, 0, nullptr);
static VeriClass s_(Primitive::Type::kPrimShort, 0, nullptr);
static VeriClass i_(Primitive::Type::kPrimInt, 0, nullptr);
static VeriClass f_(Primitive::Type::kPrimFloat, 0, nullptr);
static VeriClass d_(Primitive::Type::kPrimDouble, 0, nullptr);
static VeriClass j_(Primitive::Type::kPrimLong, 0, nullptr);
static VeriClass v_(Primitive::Type::kPrimVoid, 0, nullptr);

VeriClass* VeriClass::boolean_ = &z_;
VeriClass* VeriClass::byte_ = &b_;
VeriClass* VeriClass::char_ = &c_;
VeriClass* VeriClass::short_ = &s_;
VeriClass* VeriClass::integer_ = &i_;
VeriClass* VeriClass::float_ = &f_;
VeriClass* VeriClass::double_ = &d_;
VeriClass* VeriClass::long_ = &j_;
VeriClass* VeriClass::void_ = &v_;

// Will be set after boot classpath has been resolved.
VeriClass* VeriClass::object_ = nullptr;
VeriClass* VeriClass::class_ = nullptr;
VeriClass* VeriClass::class_loader_ = nullptr;
VeriClass* VeriClass::string_ = nullptr;
VeriClass* VeriClass::throwable_ = nullptr;
VeriMethod VeriClass::forName_ = nullptr;
VeriMethod VeriClass::getField_ = nullptr;
VeriMethod VeriClass::getDeclaredField_ = nullptr;
VeriMethod VeriClass::getMethod_ = nullptr;
VeriMethod VeriClass::getDeclaredMethod_ = nullptr;
VeriMethod VeriClass::getClass_ = nullptr;
VeriMethod VeriClass::loadClass_ = nullptr;
VeriField VeriClass::sdkInt_ = nullptr;

static const char* kDexFileOption = "--dex-file=";
static const char* kStubsOption = "--core-stubs=";
static const char* kFlagsOption = "--api-flags=";
static const char* kImprecise = "--imprecise";
static const char* kTargetSdkVersion = "--target-sdk-version=";
static const char* kOnlyReportSdkUses = "--only-report-sdk-uses";

struct VeridexOptions {
  const char* dex_file = nullptr;
  const char* core_stubs = nullptr;
  const char* flags_file = nullptr;
  bool precise = true;
  int target_sdk_version = 28; /* P */
  bool only_report_sdk_uses = false;
};

static const char* Substr(const char* str, int index) {
  return str + index;
}

static bool StartsWith(const char* str, const char* val) {
  return strlen(str) >= strlen(val) && memcmp(str, val, strlen(val)) == 0;
}

static void ParseArgs(VeridexOptions* options, int argc, char** argv) {
  // Skip over the command name.
  argv++;
  argc--;

  for (int i = 0; i < argc; ++i) {
    if (StartsWith(argv[i], kDexFileOption)) {
      options->dex_file = Substr(argv[i], strlen(kDexFileOption));
    } else if (StartsWith(argv[i], kStubsOption)) {
      options->core_stubs = Substr(argv[i], strlen(kStubsOption));
    } else if (StartsWith(argv[i], kFlagsOption)) {
      options->flags_file = Substr(argv[i], strlen(kFlagsOption));
    } else if (strcmp(argv[i], kImprecise) == 0) {
      options->precise = false;
    } else if (StartsWith(argv[i], kTargetSdkVersion)) {
      options->target_sdk_version = atoi(Substr(argv[i], strlen(kTargetSdkVersion)));
    } else if (strcmp(argv[i], kOnlyReportSdkUses) == 0) {
      options->only_report_sdk_uses = true;
    }
  }
}

static std::vector<std::string> Split(const std::string& str, char sep) {
  std::vector<std::string> tokens;
  std::string tmp;
  std::istringstream iss(str);
  while (std::getline(iss, tmp, sep)) {
    tokens.push_back(tmp);
  }
  return tokens;
}

class Veridex {
 public:
  static int Run(int argc, char** argv) {
    VeridexOptions options;
    ParseArgs(&options, argc, argv);

    if (!options.dex_file) {
      LOG(ERROR) << "Required argument '" << kDexFileOption << "' not provided.";
      return 1;
    }

    gTargetSdkVersion = options.target_sdk_version;

    std::vector<std::string> boot_content;
    std::vector<std::string> app_content;
    std::vector<std::unique_ptr<const DexFile>> boot_dex_files;
    std::vector<std::unique_ptr<const DexFile>> app_dex_files;
    std::string error_msg;

    // Read the boot classpath.
    std::vector<std::string> boot_classpath = Split(options.core_stubs, ':');
    boot_content.resize(boot_classpath.size());
    uint32_t i = 0;
    for (const std::string& str : boot_classpath) {
      if (!Load(str, boot_content[i++], &boot_dex_files, &error_msg)) {
        LOG(ERROR) << error_msg;
        return 1;
      }
    }

    // Read the apps dex files.
    std::vector<std::string> app_files = Split(options.dex_file, ':');
    app_content.resize(app_files.size());
    i = 0;
    for (const std::string& str : app_files) {
      if (!Load(str, app_content[i++], &app_dex_files, &error_msg)) {
        LOG(ERROR) << error_msg;
        return 1;
      }
    }

    // Resolve classes/methods/fields defined in each dex file.

    // Cache of types we've seen, for quick class name lookups.
    TypeMap type_map;
    // Add internally defined primitives.
    type_map["Z"] = VeriClass::boolean_;
    type_map["B"] = VeriClass::byte_;
    type_map["S"] = VeriClass::short_;
    type_map["C"] = VeriClass::char_;
    type_map["I"] = VeriClass::integer_;
    type_map["F"] = VeriClass::float_;
    type_map["D"] = VeriClass::double_;
    type_map["J"] = VeriClass::long_;
    type_map["V"] = VeriClass::void_;

    // Cache of resolvers, to easily query address in memory to VeridexResolver.
    DexResolverMap resolver_map;

    std::vector<std::unique_ptr<VeridexResolver>> boot_resolvers;
    Resolve(boot_dex_files, resolver_map, type_map, &boot_resolvers);

    // Now that boot classpath has been resolved, fill classes and reflection
    // methods.
    VeriClass::object_ = type_map["Ljava/lang/Object;"];
    VeriClass::class_ = type_map["Ljava/lang/Class;"];
    VeriClass::class_loader_ = type_map["Ljava/lang/ClassLoader;"];
    VeriClass::string_ = type_map["Ljava/lang/String;"];
    VeriClass::throwable_ = type_map["Ljava/lang/Throwable;"];
    VeriClass::forName_ = boot_resolvers[0]->LookupDeclaredMethodIn(
        *VeriClass::class_, "forName", "(Ljava/lang/String;)Ljava/lang/Class;");
    VeriClass::getField_ = boot_resolvers[0]->LookupDeclaredMethodIn(
        *VeriClass::class_, "getField", "(Ljava/lang/String;)Ljava/lang/reflect/Field;");
    VeriClass::getDeclaredField_ = boot_resolvers[0]->LookupDeclaredMethodIn(
        *VeriClass::class_, "getDeclaredField", "(Ljava/lang/String;)Ljava/lang/reflect/Field;");
    VeriClass::getMethod_ = boot_resolvers[0]->LookupDeclaredMethodIn(
        *VeriClass::class_,
        "getMethod",
        "(Ljava/lang/String;[Ljava/lang/Class;)Ljava/lang/reflect/Method;");
    VeriClass::getDeclaredMethod_ = boot_resolvers[0]->LookupDeclaredMethodIn(
        *VeriClass::class_,
        "getDeclaredMethod",
        "(Ljava/lang/String;[Ljava/lang/Class;)Ljava/lang/reflect/Method;");
    VeriClass::getClass_ = boot_resolvers[0]->LookupDeclaredMethodIn(
        *VeriClass::object_, "getClass", "()Ljava/lang/Class;");
    VeriClass::loadClass_ = boot_resolvers[0]->LookupDeclaredMethodIn(
        *VeriClass::class_loader_, "loadClass", "(Ljava/lang/String;)Ljava/lang/Class;");

    VeriClass* version = type_map["Landroid/os/Build$VERSION;"];
    if (version != nullptr) {
      VeriClass::sdkInt_ = boot_resolvers[0]->LookupFieldIn(*version, "SDK_INT", "I");
    }

    std::vector<std::unique_ptr<VeridexResolver>> app_resolvers;
    Resolve(app_dex_files, resolver_map, type_map, &app_resolvers);

    // Find and log uses of hidden APIs.
    HiddenApi hidden_api(options.flags_file, options.only_report_sdk_uses);
    HiddenApiStats stats;

    HiddenApiFinder api_finder(hidden_api);
    api_finder.Run(app_resolvers);
    api_finder.Dump(std::cout, &stats, !options.precise);

    if (options.precise) {
      PreciseHiddenApiFinder precise_api_finder(hidden_api);
      precise_api_finder.Run(app_resolvers);
      precise_api_finder.Dump(std::cout, &stats);
    }

    DumpSummaryStats(std::cout, stats, options);

    if (options.precise) {
      std::cout << "To run an analysis that can give more reflection accesses, " << std::endl
                << "but could include false positives, pass the --imprecise flag. " << std::endl;
    }

    return 0;
  }

 private:
  static void DumpSummaryStats(std::ostream& os,
                               const HiddenApiStats& stats,
                               const VeridexOptions& options) {
    static const char* kPrefix = "       ";
    if (options.only_report_sdk_uses) {
      os << stats.api_counts[hiddenapi::ApiList::Whitelist().GetIntValue()]
         << " SDK API uses." << std::endl;
    } else {
      os << stats.count << " hidden API(s) used: "
         << stats.linking_count << " linked against, "
         << stats.reflection_count << " through reflection" << std::endl;
      for (size_t i = 0; i < hiddenapi::ApiList::kValueCount; ++i) {
        hiddenapi::ApiList api_list = hiddenapi::ApiList::FromIntValue(i);
        if (api_list != hiddenapi::ApiList::Whitelist()) {
          os << kPrefix << stats.api_counts[i] << " in " << api_list << std::endl;
        }
      }
    }
  }

  static bool Load(const std::string& filename,
                   std::string& content,
                   std::vector<std::unique_ptr<const DexFile>>* dex_files,
                   std::string* error_msg) {
    if (filename.empty()) {
      *error_msg = "Missing file name";
      return false;
    }

    // TODO: once added, use an api to android::base to read a std::vector<uint8_t>.
    if (!android::base::ReadFileToString(filename.c_str(), &content)) {
      *error_msg = "ReadFileToString failed for " + filename;
      return false;
    }

    const DexFileLoader dex_file_loader;
    DexFileLoaderErrorCode error_code;
    static constexpr bool kVerifyChecksum = true;
    static constexpr bool kRunDexFileVerifier = true;
    if (!dex_file_loader.OpenAll(reinterpret_cast<const uint8_t*>(content.data()),
                                 content.size(),
                                 filename.c_str(),
                                 kRunDexFileVerifier,
                                 kVerifyChecksum,
                                 &error_code,
                                 error_msg,
                                 dex_files)) {
      if (error_code == DexFileLoaderErrorCode::kEntryNotFound) {
        LOG(INFO) << "No .dex found, skipping analysis.";
        return true;
      }
      return false;
    }

    return true;
  }

  static void Resolve(const std::vector<std::unique_ptr<const DexFile>>& dex_files,
                      DexResolverMap& resolver_map,
                      TypeMap& type_map,
                      std::vector<std::unique_ptr<VeridexResolver>>* resolvers) {
    for (const std::unique_ptr<const DexFile>& dex_file : dex_files) {
      VeridexResolver* resolver =
          new VeridexResolver(*dex_file.get(), resolver_map, type_map);
      resolvers->emplace_back(resolver);
      resolver_map[reinterpret_cast<uintptr_t>(dex_file->Begin())] = resolver;
    }

    for (const std::unique_ptr<VeridexResolver>& resolver : *resolvers) {
      resolver->Run();
    }
  }
};

}  // namespace art

int main(int argc, char** argv) {
  return art::Veridex::Run(argc, argv);
}