Added handling for mysql_native_password

src/auth.cpp

@@ -0,0 +1,36 @@
+/*
+ * auth.cpp
+ *
+ *  Created on: Jun 30, 2019
+ *      Author: ruben
+ */
+
+#include "auth.hpp"
+#include <openssl/sha.h>
+#include <cstring>
+
+// SHA1( password ) XOR SHA1( "20-bytes random data from server" <concat> SHA1( SHA1( password ) ) )
+void mysql::mysql_native_password::compute_auth_string(
+	std::string_view password,
+	const void* challenge,
+	response_buffer& output
+)
+{
+	// SHA1 (password)
+	using sha1_buffer = unsigned char [SHA_DIGEST_LENGTH];
+	sha1_buffer password_sha1;
+	SHA1(reinterpret_cast<const unsigned char*>(password.data()), password.size(), password_sha1);
+
+	// Add server challenge (salt)
+	unsigned char salted_buffer [challenge_length + SHA_DIGEST_LENGTH];
+	memcpy(salted_buffer, challenge, challenge_length);
+	SHA1(password_sha1, sizeof(password_sha1), salted_buffer + 20);
+	sha1_buffer salted_sha1;
+	SHA1(salted_buffer, sizeof(salted_buffer), salted_sha1);
+
+	// XOR
+	static_assert(sizeof(output) == SHA_DIGEST_LENGTH);
+	for (std::size_t i = 0; i < SHA_DIGEST_LENGTH; ++i)
+		output[i] = password_sha1[i] ^ salted_sha1[i];
+}
+