feat: express client support for UTF-8 in LOGIN7

Update connection featureExtAck token handling to not assume every such token
must have fedauth data.

[#1143]

src/connection.ts

@@ -3614,10 +3614,10 @@ Connection.prototype.STATE = {
             this.loginError = ConnectionError(`Active Directory authentication acknowledgment for ${authentication.type} authentication method includes extra data`);
             this.loggedIn = false;
           }
-        } else if (token.fedAuth === undefined) {
+        } else if (token.fedAuth === undefined && token.utf8Support === undefined) {
           this.loginError = ConnectionError('Received acknowledgement for unknown feature');
           this.loggedIn = false;
-        } else {
+        } else if (token.fedAuth) {
           this.loginError = ConnectionError('Did not request Active Directory authentication, but received the acknowledgment');
           this.loggedIn = false;
         }

src/login7-payload.ts

@@ -1,4 +1,5 @@
 import { sprintf } from 'sprintf-js';
+import { versions } from './tds-versions';
 
 const FLAGS_1 = {
   ENDIAN_LITTLE: 0x00,
@@ -411,6 +412,17 @@ class Login7Payload {
       }
     }
 
+    if (this.tdsVersion >= versions['7_4']) {
+      // Signal UTF-8 support: Value 0x0A, bit 0 must be set to 1. Added in TDS 7.4.
+      const UTF8_SUPPORT_FEATURE_ID = 0x0a;
+      const UTF8_SUPPORT_CLIENT_SUPPORTS_UTF8 = 0x01;
+      const buf = Buffer.alloc(6);
+      buf.writeUInt8(UTF8_SUPPORT_FEATURE_ID, 0);
+      buf.writeUInt32LE(1, 1);
+      buf.writeUInt8(UTF8_SUPPORT_CLIENT_SUPPORTS_UTF8, 5);
+      buffers.push(buf);
+    }
+
     buffers.push(Buffer.from([FEATURE_EXT_TERMINATOR]));
 
     return Buffer.concat(buffers);

test/unit/login7-payload-test.js

@@ -132,7 +132,7 @@ describe('Login7Payload', function() {
     describe('for a login payload with active directory authentication', function() {
       it('generates the expected data', function() {
         const payload = new Login7Payload({
-          tdsVersion: 0x72090002,
+          tdsVersion: 0x74000004,
           packetSize: 1024,
           clientProgVer: 0,
           clientPid: 12345,
@@ -175,7 +175,7 @@ describe('Login7Payload', function() {
           2 + 2 + (2 * payload.changePassword.length) +
           4 + // cbSSPILong
           4 + // Extension offset
-          1 + 1 + 4 + 1 + 1; // Feature ext
+          1 + (1 + 4 + 1) + (1 + 4 + 1) + 1; // Feature ext - v7.4 includes UTF8_SUPPORT unlike prior versions
 
         assert.lengthOf(data, expectedLength);
       });