From b280b87de2d7fdb57d0a2d12ee9ec06b34a5d0bc Mon Sep 17 00:00:00 2001
From: Hiroki Noda <kubo39@gmail.com>
Date: Sat, 24 Oct 2020 07:11:15 +0900
Subject: [PATCH 1/2] Use utf8mb4 by default

This commit changes default collation as "utf8mb4_generic_ci" which is
available from MySQL 5.5.3.
---
 source/mysql/protocol/comms.d | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/source/mysql/protocol/comms.d b/source/mysql/protocol/comms.d
index 94dfc9df..32ce51cf 100644
--- a/source/mysql/protocol/comms.d
+++ b/source/mysql/protocol/comms.d
@@ -25,6 +25,8 @@ import std.conv;
 import std.digest.sha;
 import std.exception;
 import std.range;
+import std.regex;
+import std.typecons;
 import std.variant;
 
 import mysql.connection;
@@ -810,7 +812,7 @@ body
 	// Request a conventional maximum packet length.
 	1.packInto(packet[8..12]);
 
-	packet ~= 33; // Set UTF-8 as default charSet
+	packet ~= getDefaultCollation(conn._serverVersion);
 
 	// There's a statutory block of zero bytes here - fill them in.
 	foreach(i; 0 .. 23)
@@ -1112,3 +1114,17 @@ package(mysql) void enableMultiStatements(Connection conn, bool on)
 	auto packet = conn.getPacket();
 	enforce!MYXProtocol(packet[0] == 254 && packet.length == 5, "Unexpected response to SET_OPTION command");
 }
+
+private ubyte getDefaultCollation(string serverVersion)
+{
+	static re = ctRegex!`^(\d{1,2})\.(\d{1,2})\.(\d{1,3})(.*)`;
+	auto captured = serverVersion.matchFirst(re);
+	auto major = captured[1].to!ushort;
+	auto minor = captured[2].to!ushort;
+	auto patch = captured[3].to!ushort;
+	auto mysqlServerVersion = tuple(major, minor, patch);
+
+	if (mysqlServerVersion >= tuple(5,5,3)) // MySQL >= 5.5.3 supports utf8mb4
+		return 45; // Set utf8mb4_general_ci as default
+	return 33; // Set utf8_general_ci as default
+}

From c2b2f26ff0f1402fc431070d0fc781a9a45fefc6 Mon Sep 17 00:00:00 2001
From: Hiroki Noda <kubo39@gmail.com>
Date: Wed, 26 May 2021 01:16:30 +0900
Subject: [PATCH 2/2] Stop using regex and add test

---
 source/mysql/protocol/comms.d | 46 ++++++++++++++++++++++-------------
 1 file changed, 29 insertions(+), 17 deletions(-)

diff --git a/source/mysql/protocol/comms.d b/source/mysql/protocol/comms.d
index 32ce51cf..a1e28997 100644
--- a/source/mysql/protocol/comms.d
+++ b/source/mysql/protocol/comms.d
@@ -21,12 +21,11 @@ Next tasks for this sub-package's cleanup:
 module mysql.protocol.comms;
 
 import std.algorithm;
+import std.array;
 import std.conv;
 import std.digest.sha;
 import std.exception;
 import std.range;
-import std.regex;
-import std.typecons;
 import std.variant;
 
 import mysql.connection;
@@ -47,7 +46,7 @@ package struct ProtocolPrepared
 	import std.datetime;
 	import std.variant;
 	import mysql.types;
-	
+
 	static ubyte[] makeBitmap(in Variant[] inParams)
 	{
 		size_t bml = (inParams.length+7)/8;
@@ -453,7 +452,7 @@ package struct ProtocolPrepared
 		Variant[] inParams, ParameterSpecialization[] psa)
 	{
 		conn.autoPurge();
-		
+
 		ubyte[] packet;
 		conn.resetPacket();
 
@@ -773,7 +772,7 @@ body
 	}
 
 	conn.autoPurge();
- 
+
 	conn.resetPacket();
 
 	ubyte[] header;
@@ -969,7 +968,7 @@ package(mysql) SvrCapFlags setClientFlags(SvrCapFlags serverCaps, SvrCapFlags ca
 	// didn't supply it
 	cCaps |= SvrCapFlags.PROTOCOL41;
 	cCaps |= SvrCapFlags.SECURE_CONNECTION;
-	
+
 	return cCaps;
 }
 
@@ -1000,7 +999,7 @@ package(mysql) PreparedServerInfo performRegister(Connection conn, const(char[])
 	scope(failure) conn.kill();
 
 	PreparedServerInfo info;
-	
+
 	conn.sendCmd(CommandType.STMT_PREPARE, sql);
 	conn._fieldCount = 0;
 
@@ -1117,14 +1116,27 @@ package(mysql) void enableMultiStatements(Connection conn, bool on)
 
 private ubyte getDefaultCollation(string serverVersion)
 {
-	static re = ctRegex!`^(\d{1,2})\.(\d{1,2})\.(\d{1,3})(.*)`;
-	auto captured = serverVersion.matchFirst(re);
-	auto major = captured[1].to!ushort;
-	auto minor = captured[2].to!ushort;
-	auto patch = captured[3].to!ushort;
-	auto mysqlServerVersion = tuple(major, minor, patch);
-
-	if (mysqlServerVersion >= tuple(5,5,3)) // MySQL >= 5.5.3 supports utf8mb4
-		return 45; // Set utf8mb4_general_ci as default
-	return 33; // Set utf8_general_ci as default
+	// MySQL >= 5.5.3 supports utf8mb4
+	const v = serverVersion
+		.splitter('.')
+		.map!(a => a.parse!ushort)
+		.array;
+
+	if (v[0] < 5)
+		return 33; // Set utf8_general_ci as default
+	if (v[1] < 5)
+		return 33; // Set utf8_general_ci as default
+	if (v[2] < 3)
+		return 33; // Set utf8_general_ci as default
+
+	return 45; // Set utf8mb4_general_ci as default
+}
+
+unittest
+{
+	assert(getDefaultCollation("5.5.3") == 45);
+	assert(getDefaultCollation("5.5.2") == 33);
+
+	// MariaDB: https://mariadb.com/kb/en/connection/#initial-handshake-packet
+	assert(getDefaultCollation("5.5.5-10.0.7-MariaDB") == 45);
 }