SMP handshake - validate key hash and protocol version

packages/simplexmq/example/simplexmq_example.dart

@@ -0,0 +1 @@
+void main() {}

packages/simplexmq/lib/src/buffer.dart

@@ -142,3 +142,13 @@ Uint8List encodeInt16(int n) {
   ByteData.sublistView(data).setInt16(0, n);
   return data;
 }
+
+extension EqualUint8List on Uint8List {
+  bool equal(Uint8List b) {
+    if (length != b.length) return false;
+    for (int i = 0; i < length; i++) {
+      if (this[i] != b[i]) return false;
+    }
+    return true;
+  }
+}

packages/simplexmq/lib/src/parser.dart

@@ -13,6 +13,7 @@ final charUpperA = cc('A');
 final charUpperZ = cc('Z');
 final charPlus = cc('+');
 final charSlash = cc('/');
+final charDot = cc('.');
 
 class Parser {
   final Uint8List _s;
@@ -70,6 +71,14 @@ class Parser {
         return true;
       });
 
+  // takes the passed char
+  bool? char(int c) => _run(() {
+        if (_s[_pos] == c) {
+          _pos++;
+          return true;
+        }
+      });
+
   // takes space
   bool? space() => _run(() {
         if (_s[_pos] == charSpace) {

packages/simplexmq/lib/src/transport.dart

@@ -1,8 +1,10 @@
 import 'dart:async';
 import 'dart:typed_data';
 import 'package:pointycastle/asymmetric/api.dart';
+import 'package:pointycastle/digests/sha256.dart';
 import 'buffer.dart';
 import 'crypto.dart';
+import 'parser.dart';
 import 'rsa_keys.dart';
 
 abstract class Transport {
@@ -51,7 +53,7 @@ class ServerHandshake {
 
 typedef SMPVersion = List<int>;
 
-// SMPVersion _currentSMPVersion = const [0, 4, 1, 0];
+SMPVersion _currentSMPVersion = const [0, 4, 1, 0];
 const int _serverHeaderSize = 8;
 const int _binaryRsaTransport = 0;
 const int _transportBlockSize = 4096;
@@ -96,7 +98,8 @@ class SMPTransportClient {
   }
 
   static void validateKeyHash_2(Uint8List rawKey, Uint8List keyHash) {
-    // todo
+    if (keyHash.equal(SHA256Digest().process(rawKey))) return;
+    throw Exception('smp handshake error: bad key hash');
   }
 
   static ServerHeader parseServerHeader(Uint8List a) {
@@ -129,10 +132,33 @@ class SMPTransportClient {
       _parseSMPVersion(await _readEncrypted());
 
   static SMPVersion _parseSMPVersion(Uint8List block) {
-    return [];
+    final p = Parser(block);
+    final SMPVersion version = [0, 0, 0, 0];
+    void setVer(int i, int? v) {
+      if (v == null || p.fail) {
+        throw Exception('smp handshake error: bad version format');
+      }
+      version[i] = v;
     }
 
-  static void _checkVersion(SMPVersion version) {}
+    for (var i = 0; i < 3; i++) {
+      final v = p.decimal();
+      p.char(charDot);
+      setVer(i, v);
+    }
+    final v = p.decimal();
+    p.space();
+    setVer(3, v);
+    return version;
+  }
+
+  static void _checkVersion(SMPVersion srvVersion) {
+    final s0 = srvVersion[0];
+    final c0 = _currentSMPVersion[0];
+    if (s0 > c0 || (s0 == c0 && srvVersion[1] > _currentSMPVersion[1])) {
+      throw Exception('smp handshake error: incompatible server version');
+    }
+  }
 
   Future<Uint8List> _readEncrypted() async {
     final block = await _conn.read(blockSize);

packages/simplexmq_io/test/transport_test.dart

@@ -1,5 +1,6 @@
 // import 'dart:io';
 import 'package:simplexmq/simplexmq.dart';
+import 'package:simplexmq/src/buffer.dart';
 import 'package:simplexmq_io/simplexmq_io.dart';
 import 'package:test/test.dart';
 
@@ -9,7 +10,9 @@ void main() {
       'establish connection (expects SMP server on localhost:5223)',
       () async {
         final conn = await SocketTransport.connect('localhost', 5223);
-        final smp = await SMPTransportClient.connect(conn);
+        final smp = await SMPTransportClient.connect(conn,
+            keyHash: decode64(
+                encodeAscii('pH7bg7B6vB3uJ1poKmClTAqr7yYWnAtapnIDN7ypKxU=')));
         expect(smp is SMPTransportClient, true);
       },
       skip: 'requires SMP server on port 5223',