Fix memory leaks in BoringSSL secure socket implementation

runtime/bin/secure_socket_boringssl.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef BIN_SECURE_SOCKET_BORINGSSL_H_
 #define BIN_SECURE_SOCKET_BORINGSSL_H_
 
 #if !defined(BIN_SECURE_SOCKET_H_)
 #error Do not include secure_socket_boringssl.h directly. Use secure_socket.h.
 #endif
@@ skipping 15 matching lines @@
 #include "bin/thread.h"
 #include "bin/utils.h"
 
 namespace dart {
 namespace bin {
 
 /* These are defined in root_certificates.cc. */
 extern const unsigned char* root_certificates_pem;
 extern unsigned int root_certificates_pem_length;
 
+class SSLContext {
+ public:
+  explicit SSLContext(SSL_CTX* context) :
+      context_(context),
+      alpn_protocol_string_(NULL) {
+  }
+
+  ~SSLContext() {
+    SSL_CTX_free(context_);
+    if (alpn_protocol_string_ != NULL) {
+      free(alpn_protocol_string_);
+    }
+  }
+
+  SSL_CTX* context() const { return context_; }
+
+  uint8_t* alpn_protocol_string() const { return alpn_protocol_string_; }
+  void set_alpn_protocol_string(uint8_t* protocol_string) {
+    if (alpn_protocol_string_ != NULL) {
+      free(alpn_protocol_string_);
+    }
+    alpn_protocol_string_ = protocol_string;
+  }
+
+ private:
+  SSL_CTX* context_;
+  uint8_t* alpn_protocol_string_;
+
+  DISALLOW_COPY_AND_ASSIGN(SSLContext);
+};
+
 /*
- * SSLFilter encapsulates the NSS SSL(TLS) code in a filter, that communicates
+ * SSLFilter encapsulates the SSL(TLS) code in a filter, that communicates
  * with the containing _SecureFilterImpl Dart object through four shared
  * ExternalByteArray buffers, for reading and writing plaintext, and
  * reading and writing encrypted text.  The filter handles handshaking
  * and certificate verification.
  */
 class SSLFilter : public ReferenceCounted<SSLFilter> {
  public:
   // These enums must agree with those in sdk/lib/io/secure_socket.dart.
   enum BufferIndex {
     kReadPlaintext,
@@ skipping 77 matching lines @@
   Dart_Handle InitializeBuffers(Dart_Handle dart_this);
   void InitializePlatformData();
 
   DISALLOW_COPY_AND_ASSIGN(SSLFilter);
 };
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // BIN_SECURE_SOCKET_BORINGSSL_H_