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

iOS/FlipperKit/FlipperWebSocket.mm

@@ -9,6 +9,7 @@
 
 #import "FlipperWebSocket.h"
 #import <Flipper/ConnectionContextStore.h>
+#import <Flipper/FlipperBase64.h>
 #import <Flipper/FlipperTransportTypes.h>
 #import <Flipper/Log.h>
 #import <folly/String.h>
@@ -71,11 +72,7 @@ class WebSocketSerializer : public FlipperPayloadSerializer {
       query += key;
       query += "=";
       if (key == "csr") {
-        NSString* csr = [NSString stringWithUTF8String:value.c_str()];
-        NSData* data = [csr dataUsingEncoding:NSUTF8StringEncoding];
-        NSString* base64 = [data base64EncodedStringWithOptions:0];
-
-        query += base64.UTF8String;
+        query += Base64::encode(value);
       } else {
         query += url_encode(value);
       }

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

xplat/Flipper/FlipperBase64.h

@@ -0,0 +1,21 @@
+/*
+ * 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.
+ */
+
+#pragma once
+
+#include <string>
+
+namespace facebook {
+namespace flipper {
+
+class Base64 {
+ public:
+  static std::string encode(const std::string& input);
+};
+
+} // namespace flipper
+} // namespace facebook