Base64 encoding using OpenSSL

Summary: This change adds a function to base64 encode. It is used to encode the CSR which gets added to the connection url.

Reviewed By: passy

Differential Revision: D31570706

fbshipit-source-id: 8356550fe87ae3ac6aae8616744a9339cf69b511

xplat/Flipper/FlipperBase64.cpp

@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#include "FlipperBase64.h"
+#include <openssl/bio.h>
+#include <openssl/buffer.h>
+#include <openssl/evp.h>
+
+namespace facebook {
+namespace flipper {
+
+std::string Base64::encode(const std::string& input) {
+  const auto base64_mem = BIO_new(BIO_s_mem());
+  auto base64 = BIO_new(BIO_f_base64());
+  base64 = BIO_push(base64, base64_mem);
+
+  BIO_set_flags(base64, BIO_FLAGS_BASE64_NO_NL);
+
+  BIO_write(base64, input.c_str(), static_cast<int>(input.length()));
+  BIO_flush(base64);
+
+  BUF_MEM* buffer_memory{};
+  BIO_get_mem_ptr(base64, &buffer_memory);
+  auto base64_encoded =
+      std::string(buffer_memory->data, buffer_memory->length - 1);
+
+  BIO_free_all(base64);
+
+  return base64_encoded;
+}
+
+} // namespace flipper
+} // namespace facebook