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src,crypto: eliminate code duplication between StatelessDiffieHellman* #40084

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src,crypto: eliminate code duplication between StatelessDiffieHellman* #40084

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52 changes: 14 additions & 38 deletions src/crypto/crypto_dh.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@

namespace node {

using v8::ArrayBuffer;
using v8::ConstructorBehavior;
using v8::DontDelete;
using v8::FunctionCallback;
Expand All @@ -28,6 +29,7 @@ using v8::ReadOnly;
using v8::SideEffectType;
using v8::Signature;
using v8::String;
using v8::Uint8Array;
using v8::Value;

namespace crypto {
Expand Down Expand Up @@ -539,41 +541,9 @@ WebCryptoKeyExportStatus DHKeyExportTraits::DoExport(
}

namespace {
AllocatedBuffer StatelessDiffieHellman(
Environment* env,
ManagedEVPPKey our_key,
ManagedEVPPKey their_key) {
size_t out_size;

EVPKeyCtxPointer ctx(EVP_PKEY_CTX_new(our_key.get(), nullptr));
if (!ctx ||
EVP_PKEY_derive_init(ctx.get()) <= 0 ||
EVP_PKEY_derive_set_peer(ctx.get(), their_key.get()) <= 0 ||
EVP_PKEY_derive(ctx.get(), nullptr, &out_size) <= 0)
return AllocatedBuffer();

AllocatedBuffer result = AllocatedBuffer::AllocateManaged(env, out_size);
CHECK_NOT_NULL(result.data());

unsigned char* data = reinterpret_cast<unsigned char*>(result.data());
if (EVP_PKEY_derive(ctx.get(), data, &out_size) <= 0)
return AllocatedBuffer();

ZeroPadDiffieHellmanSecret(out_size, &result);
return result;
}

// The version of StatelessDiffieHellman that returns an AllocatedBuffer
// is not threadsafe because of the AllocatedBuffer allocation of a
// v8::BackingStore (it'll cause much crashing if we call it from a
// libuv worker thread). This version allocates a ByteSource instead,
// which we can convert into a v8::BackingStore later.
// TODO(@jasnell): Eliminate the code duplication between these two
// versions of the function.
ByteSource StatelessDiffieHellmanThreadsafe(
Environment* env,
ManagedEVPPKey our_key,
ManagedEVPPKey their_key) {
const ManagedEVPPKey& our_key,
const ManagedEVPPKey& their_key) {
size_t out_size;

EVPKeyCtxPointer ctx(EVP_PKEY_CTX_new(our_key.get(), nullptr));
Expand Down Expand Up @@ -612,11 +582,18 @@ void DiffieHellman::Stateless(const FunctionCallbackInfo<Value>& args) {
ManagedEVPPKey our_key = our_key_object->Data()->GetAsymmetricKey();
ManagedEVPPKey their_key = their_key_object->Data()->GetAsymmetricKey();

AllocatedBuffer out = StatelessDiffieHellman(env, our_key, their_key);
if (out.size() == 0)
Local<Value> out;
{
Local<ArrayBuffer> ab = StatelessDiffieHellmanThreadsafe(our_key, their_key)
.ToArrayBuffer(env);
out = Buffer::New(env, ab, 0, ab->ByteLength())
.FromMaybe(Local<Uint8Array>());
}

if (Buffer::Length(out) == 0)
return ThrowCryptoError(env, ERR_get_error(), "diffieHellman failed");

args.GetReturnValue().Set(out.ToBuffer().FromMaybe(Local<Value>()));
args.GetReturnValue().Set(out);
}

Maybe<bool> DHBitsTraits::AdditionalConfig(
Expand Down Expand Up @@ -661,7 +638,6 @@ bool DHBitsTraits::DeriveBits(
const DHBitsConfig& params,
ByteSource* out) {
*out = StatelessDiffieHellmanThreadsafe(
env,
params.private_key->GetAsymmetricKey(),
params.public_key->GetAsymmetricKey());
return true;
Expand Down