Fix Bad logic to decode the column name #1413

Introduce character_set_results tracking to ensure that we can
read the column name properly

Author: testn

lib/commands/query.js

@@ -196,7 +196,7 @@ class Query extends Command {
     if (this._fields[this._resultIndex].length !== this._fieldCount) {
       const field = new Packets.ColumnDefinition(
         packet,
-        connection.clientEncoding
+        connection.resultEncoding
       );
       this._fields[this._resultIndex].push(field);
       if (connection.config.debug) {

lib/connection.js

@@ -79,6 +79,7 @@ class Connection extends EventEmitter {
     this._protocolError = null;
     this._outOfOrderPackets = [];
     this.clientEncoding = CharsetToEncoding[this.config.charsetNumber];
+    this.resultEncoding = CharsetToEncoding[this.config.charsetNumber];
     this.stream.on('error', this._handleNetworkError.bind(this));
     // see https://gist.github.com/khoomeister/4985691#use-that-instead-of-bind
     this.packetParser = new PacketParser(p => {

lib/connection_config.js

@@ -143,6 +143,7 @@ class ConnectionConfig {
     this.charsetNumber = options.charset
       ? ConnectionConfig.getCharsetNumber(options.charset)
       : options.charsetNumber || Charsets.UTF8MB4_UNICODE_CI;
+    this.resultSetCharsetNumber = this.charsetNumber;
     this.compress = options.compress || false;
     this.authPlugins = options.authPlugins;
     this.authSwitchHandler = options.authSwitchHandler;

lib/constants/encoding_charset.js

@@ -36,6 +36,7 @@ module.exports = {
   macroman: 39,
   cp852: 40,
   utf8: 45,
+  utf8mb3: 45,
   utf8mb4: 45,
   utf16: 54,
   utf16le: 56,

lib/packets/column_definition.js

@@ -19,9 +19,9 @@ const fields = ['catalog', 'schema', 'table', 'orgTable', 'name', 'orgName'];
 // see https://github.com/sidorares/node-mysql2/pull/137
 //
 class ColumnDefinition {
-  constructor(packet, clientEncoding) {
+  constructor(packet, resultEncoding) {
     this._buf = packet.buffer;
-    this._clientEncoding = clientEncoding;
+    this._resultEncoding = resultEncoding;
     this._catalogLength = packet.readLengthCodedNumber();
     this._catalogStart = packet.offset;
     packet.offset += this._catalogLength;
@@ -46,7 +46,7 @@ class ColumnDefinition {
     this.encoding = CharsetToEncoding[this.characterSet];
     this.name = StringParser.decode(
       this._buf,
-      this.encoding === 'binary' ? this._clientEncoding : this.encoding,
+      this._resultEncoding !== undefined ? this._resultEncoding : "utf8",
       _nameStart, 
       _nameStart + _nameLength
     );
@@ -116,7 +116,7 @@ const addString = function(name) {
       const end = start + this[`_${name}Length`];
       const val = StringParser.decode(
         this._buf,
-        this.encoding === 'binary' ? this._clientEncoding : this.encoding,
+        this._resultEncoding !== undefined ? this._resultEncoding : "utf8",
         start, 
         end
       );

lib/packets/resultset_header.js

@@ -8,6 +8,7 @@ const ClientConstants = require('../constants/client.js');
 const ServerSatusFlags = require('../constants/server_status.js');
 
 const EncodingToCharset = require('../constants/encoding_charset.js');
+const CharsetToEncoding = require('../constants/charset_encodings.js');
 const sessionInfoTypes = require('../constants/session_track.js');
 
 class ResultSetHeader {
@@ -62,8 +63,10 @@ class ResultSetHeader {
             const val = packet.readLengthCodedString(encoding);
             stateChanges.systemVariables[key] = val;
             if (key === 'character_set_client') {
-              const charsetNumber = EncodingToCharset[val];
-              connection.config.charsetNumber = charsetNumber;
+              connection.clientEncoding = CharsetToEncoding[EncodingToCharset[val]];
+            }
+            if (key === 'character_set_results') {
+              connection.resultEncoding = val === '' ? undefined : CharsetToEncoding[EncodingToCharset[val]];
             }
           } else if (type === sessionInfoTypes.SCHEMA) {
             key = packet.readLengthCodedString(encoding);

test/integration/connection/test-column-encoding.js

@@ -0,0 +1,71 @@
+'use strict';
+
+const common = require('../../common');
+const connection = common.createConnection().promise();
+const assert = require('assert');
+const { throws } = require('assert');
+
+// test data stores
+const testData = [
+  {
+    column_charset: 'tis620',
+    column_name: '平仮名',
+    data: 'กขค',
+    result_charset: 'utf8',
+  },
+  {
+    column_charset: 'tis620',
+    column_name: '平仮名',
+    data: 'กขค',
+    result_charset: null,
+  },
+  {
+    column_charset: 'tis620',
+    column_name: '平仮名',
+    data: 'กขค',
+    result_charset: 'utf8',
+  },
+  {
+    column_charset: 'tis620',
+    column_name: '平仮名',
+    data: 'กขค',
+    result_charset: 'utf8mb3',
+  },
+  {
+    column_charset: 'utf16',
+    column_name: 'กขค',
+    data: 'กขค',
+    result_charset: 'tis620',
+  },
+];
+
+let resultData = [];
+
+(async () => {
+  for (let i = 0; i < testData.length; ++i) {
+    const entry = testData[i];
+
+    await connection.query('DROP TABLE IF EXISTS `test-charset-encoding2`');
+    await connection.query('SET NAMES "utf8mb4"');
+    await connection.query(
+      'CREATE TABLE IF NOT EXISTS `test-charset-encoding2` ' +
+        `( \`${entry.column_name}\` VARCHAR(1000) CHARACTER SET "${entry.column_charset}")`
+    );
+    await connection.query('INSERT INTO `test-charset-encoding2` values(?)', [
+      entry.data,
+    ]);
+    await connection.query('SET character_set_results = ?', [
+      entry.result_charset,
+    ]);
+    const result = await connection.query(
+      'SELECT * from `test-charset-encoding2`'
+    );
+    resultData.push(result[0][0]);
+  }
+  connection.end();
+  for (let i = 0; i < testData.length; ++i) {
+    const data = {};
+    data[testData[i].column_name] = testData[i].data;
+    assert.deepEqual(resultData[i], data);
+  }
+})();