fix: skip direct OpenSSL API interaction for certificate conversion

Electron does not expose its bundled SSL library to users, unlike
Node.js (which is probably reasonable, considering that it uses
BoringSSL, which will generally have different ABI properties than
OpenSSL). As a consequence, building this addon for Electron fails
currently.

However, there is an easier solution available now that I overlooked;
the X509Certificate class available since Node.js 15.6.0 supports
direct conversion from DER to PEM as well, so no native interactions
with the OpenSSL API are actually necessary these days.

README.md

@@ -47,11 +47,3 @@ This functions returns an array of PEM-formatted certificates.
 You need to import `testkeys\certificate.pfx` manually into your local
 CA store in order for the tests to pass. Make sure to import that certificate
 with the "exportable private key" option. The password for the file is `pass`.
-
-## Compatibility
-
-Current versions of this package use OpenSSL to perform a format conversion
-from DER to PEM. This means that, unlike other Node-API addons, this addon
-has a stronger dependency on the ABI exposed by Node.js, and in particular
-may need to be updated once Node.js starts using OpenSSL 4.x (which is not
-planned at the time of writing).

binding.cc

@@ -3,9 +3,6 @@
 #include <napi.h>
 #include <windows.h>
 #include <wincrypt.h>
-#include <openssl/err.h>
-#include <openssl/x509.h>
-#include <openssl/pem.h>
 
 using namespace Napi;
 
@@ -59,13 +56,6 @@ void ThrowWindowsError(Env env, const char* call) {
   throw Error::New(env, buf);
 }
 
-void ThrowOpenSSLError(Env env, const char* call) {
-  std::string error = call;
-  error += " failed with: ";
-  error += ERR_error_string(ERR_get_error(), nullptr);
-  throw Error::New(env, error);
-}
-
 // Create a temporary certificate store, add 'cert' to it, and then
 // export it (using 'password' for encryption).
 Buffer<BYTE> CertToBuffer(Env env, PCCERT_CONTEXT cert, LPCWSTR password, DWORD export_flags) {
@@ -91,33 +81,6 @@ Buffer<BYTE> CertToBuffer(Env env, PCCERT_CONTEXT cert, LPCWSTR password, DWORD
   return outbuf;
 }
 
-// Export a X.509 certificate (which does not include a key) as a PEM string.
-String CertToPEMBuffer(Env env, PCCERT_CONTEXT cert) {
-  const unsigned char* pbCertEncoded = reinterpret_cast<const unsigned char*>(cert->pbCertEncoded);
-  X509* x509cert = d2i_X509(nullptr, &pbCertEncoded, cert->cbCertEncoded);
-  if (!x509cert) {
-    ThrowOpenSSLError(env, "d2i_X509()");
-  }
-  Cleanup cleanup_cert([&]() { X509_free(x509cert); });
-
-  BIO* bio = BIO_new(BIO_s_mem());
-  if (!bio) {
-    ThrowOpenSSLError(env, "BIO_new()");
-  }
-  Cleanup cleanup_bio([&]() { BIO_free(bio); });
-
-  if (!PEM_write_bio_X509(bio, x509cert)) {
-    ThrowOpenSSLError(env, "PEM_write_bio_X509()");
-  }
-
-  char* string_data = nullptr;
-  long string_length = BIO_get_mem_data(bio, &string_data);
-  if (!string_data || static_cast<uintmax_t>(string_length) > std::numeric_limits<size_t>::max()) {
-    ThrowOpenSSLError(env, "BIO_get_mem_data()");
-  }
-  return String::New(env, string_data, string_length);
-}
-
 class CertStoreHandle {
  public:
   CertStoreHandle(HCERTSTORE store) : store_(store) {}
@@ -175,7 +138,7 @@ Value ExportAllCertificates(const CallbackInfo& args) {
   Array result = Array::New(args.Env());
   size_t index = 0;
   while (cert = sys_cs.next()) {
-    String buf = CertToPEMBuffer(args.Env(), cert);
+    Buffer<BYTE> buf = Buffer<BYTE>::Copy(args.Env(), cert->pbCertEncoded, cert->cbCertEncoded);
     result[index++] = buf;
   }
   return result;

index.js

@@ -4,7 +4,7 @@ const {
   exportAllCertificates,
   storeTypes
 } = require('bindings')('win_export_cert');
-const { randomBytes } = require('crypto');
+const { randomBytes, X509Certificate } = require('crypto');
 const util = require('util');
 
 const DEFAULT_STORE_TYPE_LIST = ['CERT_SYSTEM_STORE_LOCAL_MACHINE', 'CERT_SYSTEM_STORE_CURRENT_USER'];
@@ -29,7 +29,8 @@ function exportSystemCertificates(opts = {}) {
   const result = new Set();
   for (const storeType of storeTypeList) {
     for (const cert of exportAllCertificates(store || 'ROOT', storeType)) {
-      result.add(cert);
+      // X509Certificate was added in Node.js 15 and accepts DER as input, but .toString() returns PEM
+      result.add(new X509Certificate(cert).toString());
     }
   }