feat: expose client's peer certificate der data (uNetworking#1062)

* expose getPeerCertificate function

* add util method to extract certificate info

* add peer certificate verification example

* lint

* return the x509cert in pem format

* check for nullptr

Author: 5shain

examples/PeerCertificate.js

@@ -0,0 +1,134 @@
+const https = require('https');
+const forge = require('node-forge');
+const crypto = require('crypto');
+const fs = require('fs');
+const path = require('path');
+// Generate CA certificate
+const ca = generateCACertificate();
+const caCertPem = pemEncodeCert(ca.cert);
+
+// Generate server certificate signed by CA
+const serverCert = generateCertificate(ca, 'localhost');
+const serverCertPem = pemEncodeCert(serverCert.cert);
+const serverKeyPem = pemEncodeKey(serverCert.privateKey);
+
+// Generate client certificate signed by CA
+const clientCert = generateCertificate(ca, 'client');
+const clientCertPem = pemEncodeCert(clientCert.cert);
+const clientKeyPem = pemEncodeKey(clientCert.privateKey);
+
+fs.writeFileSync(path.join(__dirname, "server.ca"), caCertPem);
+fs.writeFileSync(path.join(__dirname, "server.key"), serverKeyPem);
+fs.writeFileSync(path.join(__dirname, "server.cert"), serverCertPem);
+
+const uWS = require('../dist/uws');
+const port = 8086;
+
+const app = uWS.SSLApp({
+  cert_file_name: path.join(__dirname, "server.cert"),
+  key_file_name: path.join(__dirname, "server.key"),
+  ca_file_name: path.join(__dirname, "server.ca")
+}).get('/*', (res, req) => {
+  const clientCert = res.getX509Certificate();
+  const x509 = new crypto.X509Certificate(clientCert);
+  if (x509.verify(crypto.createPublicKey(caCertPem))) {
+    res.end(`Hello World! your certificate is valid!`);
+  }
+  else
+    res.end('Hello World!');
+
+}).listen(port, (token) => {
+  if (token) {
+    console.log('Listening to port ' + port);
+    sendClientRequest();
+  } else {
+    console.log('Failed to listen to port ' + port);
+  }
+});
+
+function generateCACertificate() {
+  const keys = forge.pki.rsa.generateKeyPair(2048);
+  const cert = forge.pki.createCertificate();
+  cert.publicKey = keys.publicKey;
+  cert.serialNumber = '01';
+  cert.validity.notBefore = new Date();
+  cert.validity.notAfter = new Date();
+  cert.validity.notAfter.setFullYear(cert.validity.notBefore.getFullYear() + 1);
+  const attrs = [
+    { name: 'commonName', value: 'example.org' },
+    { name: 'countryName', value: 'US' },
+    { shortName: 'ST', value: 'California' },
+    { name: 'localityName', value: 'San Francisco' },
+    { name: 'organizationName', value: 'example.org' },
+    { shortName: 'OU', value: 'Test' }
+  ];
+  cert.setSubject(attrs);
+  cert.setIssuer(attrs);
+  cert.setExtensions([{
+    name: 'basicConstraints',
+    cA: true
+  }]);
+  cert.sign(keys.privateKey, forge.md.sha256.create());
+  return {
+    privateKey: keys.privateKey,
+    publicKey: keys.publicKey,
+    cert: cert
+  };
+}
+
+function generateCertificate(ca, commonName) {
+  const keys = forge.pki.rsa.generateKeyPair(2048);
+  const cert = forge.pki.createCertificate();
+  cert.publicKey = keys.publicKey;
+  cert.serialNumber = '02';
+  cert.validity.notBefore = new Date();
+  cert.validity.notAfter = new Date();
+  cert.validity.notAfter.setFullYear(cert.validity.notBefore.getFullYear() + 1);
+  const attrs = [
+    { name: 'commonName', value: commonName }
+  ];
+  cert.setSubject(attrs);
+  cert.setIssuer(ca.cert.subject.attributes);
+  cert.sign(ca.privateKey, forge.md.sha256.create());
+  return {
+    privateKey: keys.privateKey,
+    cert: cert
+  };
+}
+
+function pemEncodeCert(cert) {
+  return forge.pki.certificateToPem(cert);
+}
+
+function pemEncodeKey(key) {
+  return forge.pki.privateKeyToPem(key);
+}
+
+function sendClientRequest() {
+  const clientOptions = {
+    hostname: 'localhost',
+    port: port,
+    path: '/',
+    method: 'GET',
+    key: clientKeyPem,
+    cert: clientCertPem,
+    ca: [caCertPem],
+    rejectUnauthorized: false
+  };
+
+  const req = https.request(clientOptions, (res) => {
+    let data = '';
+    res.on('data', (chunk) => {
+      data += chunk;
+    });
+    res.on('end', () => {
+      console.log('Response from server:', data);
+    });
+  });
+
+  req.on('error', (e) => {
+    console.error('errp', e);
+  });
+
+  req.end();
+}

src/HttpResponseWrapper.h

@@ -183,6 +183,18 @@ struct HttpResponseWrapper {
         }
     }
 
+    template <int PROTOCOL>
+    static void res_getX509Certificate(const FunctionCallbackInfo<Value> &args) {
+        Isolate *isolate = args.GetIsolate();
+        auto *res = getHttpResponse<PROTOCOL>(args);
+        if (res) {
+            void* sslHandle = res->getNativeHandle();
+            SSL* ssl = static_cast<SSL*>(sslHandle);
+            std::string x509cert = extractX509PemCertificate(ssl);
+            args.GetReturnValue().Set(String::NewFromUtf8(isolate, x509cert.c_str(), NewStringType::kNormal).ToLocalChecked());
+        }
+    }
+
     /* Returns the current write offset */
     template <int SSL>
     static void res_getWriteOffset(const FunctionCallbackInfo<Value> &args) {
@@ -466,6 +478,10 @@ struct HttpResponseWrapper {
             }
         }
 
+        if constexpr (SSL == 1) {
+            resTemplateLocal->PrototypeTemplate()->Set(String::NewFromUtf8(isolate, "getX509Certificate", NewStringType::kNormal).ToLocalChecked(), FunctionTemplate::New(isolate, res_getX509Certificate<SSL>));
+        }
+        
         /* Create our template */
         Local<Object> resObjectLocal = resTemplateLocal->GetFunction(isolate->GetCurrentContext()).ToLocalChecked()->NewInstance(isolate->GetCurrentContext()).ToLocalChecked();
 

src/Utilities.h

@@ -18,6 +18,8 @@
 #ifndef ADDON_UTILITIES_H
 #define ADDON_UTILITIES_H
 
+#include <openssl/ssl.h>
+#include <openssl/x509.h>
 #include <v8.h>
 using namespace v8;
 
@@ -169,4 +171,35 @@ class NativeString {
     }
 };
 
+// Utility function to extract raw certificate data
+std::string extractX509PemCertificate(SSL* ssl) {
+    std::string pemCertificate;
+
+    if (!ssl) {
+        return pemCertificate;
+    }
+
+    // Get the peer certificate
+    X509* peerCertificate = SSL_get_peer_certificate(ssl);
+    if (!peerCertificate) {
+        // No peer certificate available
+        return pemCertificate;
+    }
+
+    // Convert X509 certificate to PEM format
+    BIO* bio = BIO_new(BIO_s_mem());
+    if(bio) {
+        if (PEM_write_bio_X509(bio, peerCertificate)) {
+            char* buffer;
+            long length = BIO_get_mem_data(bio, &buffer);
+            pemCertificate.assign(buffer, length);
+        }
+        BIO_free(bio);
+    }
+
+    // Free the peer certificate
+    X509_free(peerCertificate);
+    return pemCertificate;
+}
+
 #endif