src/crypto/crypto_util.h - main - githubmirror/node

src/crypto/crypto_util.h
774 строки26 KB
Filip Skokan
src: report why --enable-fips failed
05 авг 2026, 17:49
05 авг 2026, 17:49b79dcdf
#ifndef SRC_CRYPTO_CRYPTO_UTIL_H_
#define SRC_CRYPTO_CRYPTO_UTIL_H_

#if defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS

#include "async_wrap.h"
#include "env.h"
#include "node_errors.h"
#include "node_external_reference.h"
#include "node_internals.h"
#include "string_bytes.h"
#include "util.h"
#include "v8.h"

#include "ncrypto.h"

#include <algorithm>
#include <climits>
#include <cstdio>
#include <memory>
#include <optional>
#include <string>
#include <vector>

#if OPENSSL_VERSION_NUMBER >= 0x30200000L && !defined(OPENSSL_NO_COMP_ALG)
#define NODE_OPENSSL_HAS_CERT_COMP 1
#endif

namespace node {
namespace crypto {
class ByteSource;
}

template <>
struct MemoryRetainerTraits<crypto::ByteSource> {
  static void MemoryInfo(MemoryTracker* tracker,
                         const crypto::ByteSource& value);
  static const char* MemoryInfoName(const crypto::ByteSource& value);
  static size_t SelfSize(const crypto::ByteSource& value);
};
}  // namespace node

namespace node::crypto {
// Currently known sizes of commonly used OpenSSL struct sizes.
// OpenSSL considers it's various structs to be opaque and the
// sizes may change from one version of OpenSSL to another, so
// these values should not be trusted to remain static. These
// are provided to allow for some close to reasonable memory
// tracking.
constexpr size_t kSizeOf_DH = 144;
constexpr size_t kSizeOf_EC_KEY = 80;
constexpr size_t kSizeOf_EVP_CIPHER_CTX = 168;
constexpr size_t kSizeOf_EVP_MD_CTX = 48;
constexpr size_t kSizeOf_EVP_PKEY = 72;
constexpr size_t kSizeOf_EVP_PKEY_CTX = 80;
constexpr size_t kSizeOf_HMAC_CTX = 32;
constexpr size_t kSizeOf_SSL_CTX = 240;
constexpr size_t kSizeOf_X509 = 128;

template <typename T>
constexpr T NumBitsToBytes(T bits) {
  return (bits / CHAR_BIT) + ((CHAR_BIT - 1 + (bits % CHAR_BIT)) / CHAR_BIT);
}

// Applies the FIPS related command line options. Returns a description of
// what went wrong, or std::nullopt when there was nothing to do or the
// options were applied successfully.
std::optional<std::string> ProcessFipsOptions();

bool InitCryptoOnce(v8::Isolate* isolate);
void InitCryptoOnce();

void InitCrypto(v8::Local<v8::Object> target);

extern void UseExtraCaCerts(std::string_view file);
void CleanupCachedRootCertificates();

int PasswordCallback(char* buf, int size, int rwflag, void* u);
int NoPasswordCallback(char* buf, int size, int rwflag, void* u);

// Decode is used by the various stream-based crypto utilities to decode
// string input.
template <typename T>
void Decode(const v8::FunctionCallbackInfo<v8::Value>& args,
            void (*callback)(T*, const v8::FunctionCallbackInfo<v8::Value>&,
                             const char*, size_t)) {
  T* ctx;
  ASSIGN_OR_RETURN_UNWRAP(&ctx, args.This());

  if (args[0]->IsString()) {
    StringBytes::InlineDecoder decoder;
    Environment* env = Environment::GetCurrent(args);
    enum encoding enc = ParseEncoding(env->isolate(), args[1], UTF8);
    if (decoder.Decode(env, args[0].As<v8::String>(), enc).IsNothing())
      return;
    callback(ctx, args, decoder.out(), decoder.size());
  } else {
    ArrayBufferViewContents<char> buf(args[0]);
    callback(ctx, args, buf.data(), buf.length());
  }
}

#define NODE_CRYPTO_ERROR_CODES_MAP(V)                                         \
  V(ALLOCATION_FAILED, "Failed to allocate output buffer")                     \
  V(ARGON2_FAILED, "Argon2 derivation failed")                                 \
  V(CIPHER_JOB_FAILED, "Cipher job failed")                                    \
  V(CONTEXT_UNSUPPORTED, "Context parameter is unsupported")                   \
  V(DECAPSULATION_FAILED, "Decapsulation failed")                              \
  V(DERIVING_BITS_FAILED, "Deriving bits failed")                              \
  V(ECDH_FAILED, "ECDH key agreement failed")                                  \
  V(ENCAPSULATION_FAILED, "Encapsulation failed")                              \
  V(ENGINE_NOT_FOUND, "Engine \"%s\" was not found")                           \
  V(HKDF_FAILED, "HKDF derivation failed")                                     \
  V(INVALID_KEY_TYPE, "Invalid key type")                                      \
  V(KEY_GENERATION_JOB_FAILED, "Key generation job failed")                    \
  V(KMAC_FAILED, "KMAC derivation failed")                                     \
  V(OK, "Ok")                                                                  \
  V(PBKDF2_FAILED, "PBKDF2 derivation failed")                                 \
  V(SCRYPT_FAILED, "scrypt derivation failed")

enum class NodeCryptoError {
#define V(CODE, DESCRIPTION) CODE,
  NODE_CRYPTO_ERROR_CODES_MAP(V)
#undef V
};

template <typename... Args>
std::string getNodeCryptoErrorString(const NodeCryptoError error,
                                     Args&&... args) {
  const char* error_string = nullptr;
  switch (error) {
#define V(CODE, DESCRIPTION)                                                   \
  case NodeCryptoError::CODE:                                                  \
    error_string = DESCRIPTION;                                                \
    break;
    NODE_CRYPTO_ERROR_CODES_MAP(V)
#undef V
  }
  return SPrintF(error_string, std::forward<Args>(args)...);
}

// Utility struct used to harvest error information from openssl's error stack
struct CryptoErrorStore final : public MemoryRetainer {
 public:
  void Capture();

  bool Empty() const;

  template <typename... Args>
  void Insert(const NodeCryptoError error, Args&&... args);

  v8::MaybeLocal<v8::Value> ToException(
      Environment* env,
      v8::Local<v8::String> exception_string = v8::Local<v8::String>()) const;

  void SetNodeErrorCode(const char* code) { node_error_code_ = code; }

  SET_NO_MEMORY_INFO()
  SET_MEMORY_INFO_NAME(CryptoErrorStore)
  SET_SELF_SIZE(CryptoErrorStore)

 private:
  std::vector<std::string> errors_;
  unsigned long primary_openssl_error_ = 0;  // NOLINT(runtime/int)
  const char* node_error_code_ = nullptr;
};

template <typename... Args>
void CryptoErrorStore::Insert(const NodeCryptoError error, Args&&... args) {
  const char* error_string = nullptr;
  switch (error) {
#define V(CODE, DESCRIPTION) \
    case NodeCryptoError::CODE: error_string = DESCRIPTION; break;
    NODE_CRYPTO_ERROR_CODES_MAP(V)
#undef V
  }
  errors_.emplace_back(SPrintF(error_string,
                               std::forward<Args>(args)...));
}

v8::MaybeLocal<v8::Value> cryptoErrorListToException(
    Environment* env, const ncrypto::CryptoErrorList& errors);

template <typename T>
T* MallocOpenSSL(size_t count) {
  void* mem = OPENSSL_malloc(MultiplyWithOverflowCheck(count, sizeof(T)));
  CHECK_IMPLIES(mem == nullptr, count == 0);
  return static_cast<T*>(mem);
}

// A helper class representing a read-only byte array. When deallocated, its
// contents are zeroed.
class ByteSource final {
 public:
  ByteSource() = default;
  ByteSource(ByteSource&& other) noexcept;
  ~ByteSource();

  ByteSource& operator=(ByteSource&& other) noexcept;

  ByteSource(const ByteSource&) = delete;
  ByteSource& operator=(const ByteSource&) = delete;

  template <typename T = void>
  inline const T* data() const {
    return reinterpret_cast<const T*>(data_);
  }

  template <typename T = void>
  operator ncrypto::Buffer<const T>() const {
    return ncrypto::Buffer<const T>{
        .data = data<T>(),
        .len = size(),
    };
  }

  inline size_t size() const { return size_; }

  inline bool empty() const { return size_ == 0; }

  inline operator bool() const { return data_ != nullptr; }

  inline ncrypto::BignumPointer ToBN() const {
    return ncrypto::BignumPointer(data<unsigned char>(), size());
  }

  // Creates a v8::BackingStore that takes over responsibility for
  // any allocated data. The ByteSource will be reset with size = 0
  // after being called.
  std::unique_ptr<v8::BackingStore> ReleaseToBackingStore(Environment* env);

  v8::Local<v8::ArrayBuffer> ToArrayBuffer(Environment* env);

  v8::MaybeLocal<v8::Uint8Array> ToBuffer(Environment* env);

  static ByteSource Allocated(void* data, size_t size);

  template <typename T>
  static ByteSource Allocated(const ncrypto::Buffer<T>& buffer) {
    return Allocated(buffer.data, buffer.len);
  }

  static ByteSource Foreign(const void* data, size_t size);

  static ByteSource FromEncodedString(Environment* env,
                                      v8::Local<v8::String> value,
                                      enum encoding enc = BASE64);

  static ByteSource FromStringOrBuffer(Environment* env,
                                       v8::Local<v8::Value> value);

  static ByteSource FromString(Environment* env,
                               v8::Local<v8::String> str,
                               bool ntc = false);

  static ByteSource FromBuffer(v8::Local<v8::Value> buffer,
                               bool ntc = false);

  static ByteSource FromBIO(const ncrypto::BIOPointer& bio);

  static ByteSource NullTerminatedCopy(Environment* env,
                                       v8::Local<v8::Value> value);

  static ByteSource FromSymmetricKeyObjectHandle(v8::Local<v8::Value> handle);

  static ByteSource FromSecretKeyBytes(
      Environment* env, v8::Local<v8::Value> value);

 private:
  friend struct node::MemoryRetainerTraits<ByteSource>;
  friend void TruncateToBitLength(size_t length_bits, ByteSource* bytes);

  const void* data_ = nullptr;
  void* allocated_data_ = nullptr;
  size_t size_ = 0;

  ByteSource(const void* data, void* allocated_data, size_t size)
      : data_(data), allocated_data_(allocated_data), size_(size) {}
};

void TruncateToBitLength(size_t length_bits, ByteSource* bytes);

enum CryptoJobMode { kCryptoJobAsync, kCryptoJobSync, kCryptoJobWebCrypto };

CryptoJobMode GetCryptoJobMode(v8::Local<v8::Value> args);
bool IsCryptoJobAsync(CryptoJobMode mode);

v8::MaybeLocal<v8::Value> CreateWebCryptoJobError(Environment* env,
                                                  v8::Local<v8::Value> cause);

v8::MaybeLocal<v8::Value> ToWebCryptoJobResult(Environment* env,
                                               v8::Local<v8::Value> value);

template <typename CryptoJobTraits>
class CryptoJob : public AsyncWrap, public ThreadPoolWork {
 public:
  using AdditionalParams = typename CryptoJobTraits::AdditionalParameters;

  explicit CryptoJob(Environment* env,
                     v8::Local<v8::Object> object,
                     AsyncWrap::ProviderType type,
                     CryptoJobMode mode,
                     AdditionalParams&& params)
      : AsyncWrap(env, object, type),
        ThreadPoolWork(env, "crypto"),
        mode_(mode),
        params_(std::move(params)) {
    // If the CryptoJob is async, then the instance will be
    // cleaned up when AfterThreadPoolWork is called.
    if (mode == kCryptoJobSync) MakeWeak();
  }

  bool IsNotIndicativeOfMemoryLeakAtExit() const override {
    // CryptoJobs run a work in the libuv thread pool and may still
    // exist when the event loop empties and starts to exit.
    return true;
  }

  void AfterThreadPoolWork(int status) override {
    Environment* env = AsyncWrap::env();
    CHECK(IsCryptoJobAsync(mode_));
    CHECK(status == 0 || status == UV_ECANCELED);
    std::unique_ptr<CryptoJob> ptr(this);
    if (mode_ == kCryptoJobWebCrypto) {
      v8::HandleScope handle_scope(env->isolate());
      v8::Context::Scope context_scope(env->context());
      InternalCallbackScope callback_scope(this);

      if (status == UV_ECANCELED) {
        v8::Local<v8::Value> exception = v8::Exception::Error(
            OneByteString(env->isolate(), "The operation was canceled"));
        ptr->RejectWebCrypto(exception);
        return;
      }

      v8::Local<v8::Value> err;
      v8::Local<v8::Value> result;
      {
        node::errors::TryCatchScope try_catch(env);
        if (ptr->ToResult(&err, &result).IsNothing()) {
          CHECK(try_catch.HasCaught());
          CHECK(try_catch.CanContinue());
          err = try_catch.Exception();
        }
      }

      if (!err.IsEmpty() && !err->IsUndefined()) {
        ptr->RejectWebCrypto(err);
        return;
      }

      CHECK(!result.IsEmpty());
      v8::Local<v8::Value> webcrypto_result;
      {
        node::errors::TryCatchScope try_catch(env);
        if (!ToWebCryptoJobResult(env, result).ToLocal(&webcrypto_result)) {
          CHECK(try_catch.HasCaught());
          CHECK(try_catch.CanContinue());
          ptr->RejectWebCrypto(try_catch.Exception());
          return;
        }
      }

      ptr->ResolveWebCrypto(webcrypto_result);
      return;
    }

    // If the job was canceled do not execute the callback.
    // TODO(@jasnell): We should likely revisit skipping the
    // callback on cancel as that could leave the JS in a pending
    // state (e.g. unresolved promises...)
    if (status == UV_ECANCELED) return;
    v8::HandleScope handle_scope(env->isolate());
    v8::Context::Scope context_scope(env->context());

    v8::Local<v8::Value> exception;
    v8::Local<v8::Value> args[2];
    {
      node::errors::TryCatchScope try_catch(env);
      // If ToResult returns Nothing, then an exception should have been
      // thrown and we should have caught it. Otherwise, args[0] and args[1]
      // both should have been set to a value, even if the value is undefined.
      if (ptr->ToResult(&args[0], &args[1]).IsNothing()) {
        CHECK(try_catch.HasCaught());
        CHECK(try_catch.CanContinue());
        exception = try_catch.Exception();
      }
    }

    if (!exception.IsEmpty()) {
      ptr->MakeCallback(env->ondone_string(), 1, &exception);
    } else {
      CHECK(!args[0].IsEmpty());
      CHECK(!args[1].IsEmpty());
      ptr->MakeCallback(env->ondone_string(), arraysize(args), args);
    }
  }

  virtual v8::Maybe<void> ToResult(v8::Local<v8::Value>* err,
                                   v8::Local<v8::Value>* result) = 0;

  CryptoJobMode mode() const { return mode_; }

  CryptoErrorStore* errors() { return &errors_; }

  AdditionalParams* params() { return &params_; }

  const char* MemoryInfoName() const override {
    return CryptoJobTraits::JobName;
  }

  void MemoryInfo(MemoryTracker* tracker) const override {
    tracker->TrackField("params", params_);
    tracker->TrackField("errors", errors_);
  }

  static void Run(const v8::FunctionCallbackInfo<v8::Value>& args) {
    Environment* env = Environment::GetCurrent(args);

    CryptoJob<CryptoJobTraits>* job;
    ASSIGN_OR_RETURN_UNWRAP(&job, args.This());
    if (job->mode() == kCryptoJobWebCrypto) {
      v8::Local<v8::Promise::Resolver> resolver;
      if (!v8::Promise::Resolver::New(env->context()).ToLocal(&resolver)) {
        return;
      }

      CHECK(job->resolver_.IsEmpty());
      job->resolver_.Reset(env->isolate(), resolver);
      args.GetReturnValue().Set(resolver->GetPromise());

      return job->ScheduleWork();
    }

    if (job->mode() == kCryptoJobAsync)
      return job->ScheduleWork();

    v8::Local<v8::Value> ret[2];
    env->PrintSyncTrace();
    job->DoThreadPoolWork();
    if (job->ToResult(&ret[0], &ret[1]).IsJust()) {
      CHECK(!ret[0].IsEmpty());
      CHECK(!ret[1].IsEmpty());
      args.GetReturnValue().Set(
          v8::Array::New(env->isolate(), ret, arraysize(ret)));
    }
  }

  static void Initialize(
      v8::FunctionCallback new_fn,
      Environment* env,
      v8::Local<v8::Object> target) {
    v8::Isolate* isolate = env->isolate();
    v8::HandleScope scope(isolate);
    v8::Local<v8::Context> context = env->context();
    v8::Local<v8::FunctionTemplate> job = NewFunctionTemplate(isolate, new_fn);
    job->Inherit(AsyncWrap::GetConstructorTemplate(env));
    job->InstanceTemplate()->SetInternalFieldCount(
        CryptoJob::kInternalFieldCount);
    SetProtoMethod(isolate, job, "run", Run);
    SetConstructorFunction(context, target, CryptoJobTraits::JobName, job);
  }

  static void RegisterExternalReferences(v8::FunctionCallback new_fn,
                                         ExternalReferenceRegistry* registry) {
    registry->Register(new_fn);
    registry->Register(Run);
  }

 private:
  void ResolveWebCrypto(v8::Local<v8::Value> value) {
    Environment* env = AsyncWrap::env();
    v8::Local<v8::Context> context = env->context();
    v8::Local<v8::Promise::Resolver> resolver =
        v8::Local<v8::Promise::Resolver>::New(env->isolate(), resolver_);

    bool should_delete_then = false;
    v8::Local<v8::String> then_key;
    v8::Local<v8::Value> exception;
    {
      node::errors::TryCatchScope try_catch(env);
      if (value->IsObject()) {
        then_key = env->then_string();
        v8::Local<v8::Object> object = value.As<v8::Object>();
        v8::Maybe<bool> has_own_then =
            object->HasOwnProperty(context, then_key);
        if (has_own_then.IsNothing()) {
          if (try_catch.HasCaught() && try_catch.CanContinue()) {
            exception = try_catch.Exception();
          }
        } else if (!has_own_then.FromJust()) {
          if (object
                  ->DefineOwnProperty(context,
                                      then_key,
                                      v8::Undefined(env->isolate()),
                                      v8::DontEnum)
                  .FromMaybe(false)) {
            should_delete_then = true;
          } else if (try_catch.HasCaught() && try_catch.CanContinue()) {
            exception = try_catch.Exception();
          } else {
            exception = v8::Exception::Error(OneByteString(
                env->isolate(), "Failed to prepare WebCrypto job result"));
          }
        }
      }

      if (exception.IsEmpty() && resolver->Resolve(context, value).IsJust()) {
        if (should_delete_then) {
          USE(value.As<v8::Object>()->Delete(context, then_key));
        }
        resolver_.Reset();
        return;
      }
      if (try_catch.HasCaught() && try_catch.CanContinue()) {
        exception = try_catch.Exception();
      }
    }

    if (should_delete_then) {
      USE(value.As<v8::Object>()->Delete(context, then_key));
    }
    if (!exception.IsEmpty()) {
      USE(resolver->Reject(context, exception));
    }
    resolver_.Reset();
  }

  void RejectWebCrypto(v8::Local<v8::Value> cause) {
    Environment* env = AsyncWrap::env();
    v8::Local<v8::Value> exception;
    if (!CreateWebCryptoJobError(env, cause).ToLocal(&exception)) {
      exception = cause;
    }
    v8::Local<v8::Promise::Resolver> resolver =
        v8::Local<v8::Promise::Resolver>::New(env->isolate(), resolver_);
    USE(resolver->Reject(env->context(), exception));
    resolver_.Reset();
  }

  const CryptoJobMode mode_;
  CryptoErrorStore errors_;
  AdditionalParams params_;
  v8::Global<v8::Promise::Resolver> resolver_;
};

template <typename DeriveBitsTraits>
class DeriveBitsJob final : public CryptoJob<DeriveBitsTraits> {
 public:
  using AdditionalParams = typename DeriveBitsTraits::AdditionalParameters;

  static void New(const v8::FunctionCallbackInfo<v8::Value>& args) {
    Environment* env = Environment::GetCurrent(args);

    CryptoJobMode mode = GetCryptoJobMode(args[0]);

    AdditionalParams params;
    if (DeriveBitsTraits::AdditionalConfig(mode, args, 1, &params)
            .IsNothing()) {
      // The DeriveBitsTraits::AdditionalConfig is responsible for
      // calling an appropriate THROW_CRYPTO_* variant reporting
      // whatever error caused initialization to fail.
      return;
    }

    new DeriveBitsJob(env, args.This(), mode, std::move(params));
  }

  static void Initialize(
      Environment* env,
      v8::Local<v8::Object> target) {
    CryptoJob<DeriveBitsTraits>::Initialize(New, env, target);
  }

  static void RegisterExternalReferences(ExternalReferenceRegistry* registry) {
    CryptoJob<DeriveBitsTraits>::RegisterExternalReferences(New, registry);
  }

  DeriveBitsJob(Environment* env,
                v8::Local<v8::Object> object,
                CryptoJobMode mode,
                AdditionalParams&& params)
      : CryptoJob<DeriveBitsTraits>(
            env, object, DeriveBitsTraits::Provider, mode, std::move(params)) {}

  void DoThreadPoolWork() override {
    ncrypto::ClearErrorOnReturn clear_error_on_return;
    CryptoErrorStore* errors = CryptoJob<DeriveBitsTraits>::errors();
    if (!DeriveBitsTraits::DeriveBits(AsyncWrap::env(),
                                      *CryptoJob<DeriveBitsTraits>::params(),
                                      &out_,
                                      this->mode(),
                                      errors)) {
      if (errors->Empty()) errors->Capture();
      if (errors->Empty()) {
        errors->Insert(NodeCryptoError::DERIVING_BITS_FAILED);
        errors->SetNodeErrorCode("ERR_CRYPTO_OPERATION_FAILED");
      }
      return;
    }
    success_ = true;
  }

  v8::Maybe<void> ToResult(v8::Local<v8::Value>* err,
                           v8::Local<v8::Value>* result) override {
    Environment* env = AsyncWrap::env();
    CryptoErrorStore* errors = CryptoJob<DeriveBitsTraits>::errors();
    if (success_) {
      CHECK(errors->Empty());
      *err = v8::Undefined(env->isolate());
      if (!DeriveBitsTraits::EncodeOutput(
               env, *CryptoJob<DeriveBitsTraits>::params(), &out_)
               .ToLocal(result)) {
        return v8::Nothing<void>();
      }
    } else {
      if (errors->Empty()) errors->Capture();
      CHECK(!errors->Empty());
      *result = v8::Undefined(env->isolate());
      if (!errors->ToException(env).ToLocal(err)) {
        return v8::Nothing<void>();
      }
    }
    CHECK(!result->IsEmpty());
    CHECK(!err->IsEmpty());
    return v8::JustVoid();
  }

  SET_SELF_SIZE(DeriveBitsJob)
  void MemoryInfo(MemoryTracker* tracker) const override {
    tracker->TraitTrackInline(out_, "out");
    CryptoJob<DeriveBitsTraits>::MemoryInfo(tracker);
  }

 private:
  ByteSource out_;
  bool success_ = false;
};

void ThrowCryptoError(Environment* env,
                      unsigned long err,  // NOLINT(runtime/int)
                      const char* message = nullptr);

// WebIDL AllowSharedBufferSource.
inline bool IsAnyBufferSource(v8::Local<v8::Value> arg) {
  return arg->IsArrayBufferView() ||
         arg->IsArrayBuffer() ||
         arg->IsSharedArrayBuffer();
}

template <typename T>
class ArrayBufferOrViewContents final {
 public:
  ArrayBufferOrViewContents() = default;
  ArrayBufferOrViewContents(const ArrayBufferOrViewContents&) = delete;
  void operator=(const ArrayBufferOrViewContents&) = delete;

  inline explicit ArrayBufferOrViewContents(v8::Local<v8::Value> buf) {
    if (buf.IsEmpty()) {
      return;
    }

    CHECK(IsAnyBufferSource(buf));
    if (buf->IsArrayBufferView()) {
      auto view = buf.As<v8::ArrayBufferView>();
      offset_ = view->ByteOffset();
      length_ = view->ByteLength();
      data_ = view->Buffer()->Data();
    } else if (buf->IsArrayBuffer()) {
      auto ab = buf.As<v8::ArrayBuffer>();
      offset_ = 0;
      length_ = ab->ByteLength();
      data_ = ab->Data();
    } else {
      auto sab = buf.As<v8::SharedArrayBuffer>();
      offset_ = 0;
      length_ = sab->ByteLength();
      data_ = sab->Data();
    }
  }

  inline const T* data() const {
    // Ideally, these would return nullptr if IsEmpty() or length_ is zero,
    // but some of the openssl API react badly if given a nullptr even when
    // length is zero, so we have to return something.
    if (empty()) return &buf;
    return reinterpret_cast<T*>(data_) + offset_;
  }

  inline T* data() {
    // Ideally, these would return nullptr if IsEmpty() or length_ is zero,
    // but some of the openssl API react badly if given a nullptr even when
    // length is zero, so we have to return something.
    if (empty()) return &buf;
    return reinterpret_cast<T*>(data_) + offset_;
  }

  inline size_t size() const { return length_; }

  inline bool empty() const { return length_ == 0; }

  // In most cases, input buffer sizes passed in to openssl need to
  // be limited to <= INT_MAX. This utility method helps us check.
  inline bool CheckSizeInt32() { return size() <= INT_MAX; }

  inline ByteSource ToByteSource() const {
    return ByteSource::Foreign(data(), size());
  }

  inline ByteSource ToCopy() const {
    if (empty()) return {};
    auto buf = ncrypto::DataPointer::Alloc(size());
    memcpy(buf.get(), data(), size());
    return ByteSource::Allocated(buf.release());
  }

  inline ByteSource ToNullTerminatedCopy() const {
    if (empty()) return {};
    auto buf = ncrypto::DataPointer::Alloc(size() + 1);
    memcpy(buf.get(), data(), size());
    static_cast<char*>(buf.get())[size()] = 0;
    return ByteSource::Allocated(buf.release());
  }

  inline ncrypto::DataPointer ToDataPointer() const {
    if (empty()) return {};
    if (auto dp = ncrypto::DataPointer::Alloc(size())) {
      memcpy(dp.get(), data(), size());
      return dp;
    }
    return {};
  }

  template <typename M>
  void CopyTo(M* dest, size_t len) const {
    static_assert(sizeof(M) == 1, "sizeof(M) must equal 1");
    len = std::min(len, size());
    if (len > 0 && data() != nullptr) {
      memcpy(dest, data(), len);
    }
  }

 private:
  T buf = 0;
  size_t offset_ = 0;
  size_t length_ = 0;
  void* data_ = nullptr;

  // Declaring operator new and delete as deleted is not spec compliant.
  // Therefore declare them private instead to disable dynamic alloc
  void* operator new(size_t);
  void* operator new[](size_t);
  void operator delete(void*);
  void operator delete[](void*);
};

v8::MaybeLocal<v8::Value> EncodeBignum(Environment* env,
                                       const BIGNUM* bn,
                                       int size);

v8::Maybe<void> SetEncodedValue(Environment* env,
                                v8::Local<v8::Object> target,
                                v8::Local<v8::String> name,
                                const BIGNUM* bn,
                                int size = 0);

namespace Util {
void Initialize(Environment* env, v8::Local<v8::Object> target);
void RegisterExternalReferences(ExternalReferenceRegistry* registry);
}  // namespace Util
}  // namespace node::crypto

#endif  // defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS
#endif  // SRC_CRYPTO_CRYPTO_UTIL_H_