Add swarm mode transport doc

2026-08-11 16:30:28 +00:00 · 2026-03-07 14:13:54 +01:00
parent 4e76898c8d
commit 0e4f727e26
43 changed files with 3831 additions and 1078 deletions
--- a/lib/utils/media_swarm_protocol.dart
+++ b/lib/utils/media_swarm_protocol.dart
@@ -0,0 +1,168 @@
+import 'dart:typed_data';
+
+const int _swarmMagic = 0x6d; // 'm'
+const int _swarmKindRequest = 0x01;
+const int _swarmKindAvailability = 0x02;
+
+class MediaSwarmRequest {
+  final String mediaType;
+  final String sessionId;
+  final String requesterKey6;
+  final List<int> missingIndices;
+
+  const MediaSwarmRequest({
+    required this.mediaType,
+    required this.sessionId,
+    required this.requesterKey6,
+    this.missingIndices = const [],
+  });
+
+  bool get requestsAll => missingIndices.isEmpty;
+
+  Uint8List encodeBinary() {
+    final normalizedMissing = missingIndices.toSet().toList()..sort();
+    final out = Uint8List(14 + normalizedMissing.length);
+    out[0] = _swarmMagic;
+    out[1] = _swarmKindRequest;
+    out[2] = _encodeMediaType(mediaType);
+    _writeSessionId(out, 3, sessionId);
+    _writeKey6(out, 7, requesterKey6);
+    out[13] = normalizedMissing.length;
+    for (var i = 0; i < normalizedMissing.length; i++) {
+      out[14 + i] = normalizedMissing[i];
+    }
+    return out;
+  }
+
+  static MediaSwarmRequest? tryParseBinary(Uint8List payload) {
+    if (payload.length < 14 ||
+        payload[0] != _swarmMagic ||
+        payload[1] != _swarmKindRequest) {
+      return null;
+    }
+
+    final mediaType = _decodeMediaType(payload[2]);
+    if (mediaType == null) return null;
+
+    final missingCount = payload[13];
+    if (payload.length != 14 + missingCount) {
+      return null;
+    }
+
+    return MediaSwarmRequest(
+      mediaType: mediaType,
+      sessionId: _readSessionId(payload, 3),
+      requesterKey6: _readKey6(payload, 7),
+      missingIndices: payload.sublist(14),
+    );
+  }
+}
+
+class MediaSwarmAvailability {
+  final String mediaType;
+  final String sessionId;
+  final String requesterKey6;
+  final String responderKey6;
+  final List<int> availableIndices;
+
+  const MediaSwarmAvailability({
+    required this.mediaType,
+    required this.sessionId,
+    required this.requesterKey6,
+    required this.responderKey6,
+    required this.availableIndices,
+  });
+
+  bool get servesAll => availableIndices.isEmpty;
+
+  Uint8List encodeBinary() {
+    final normalizedAvailable = availableIndices.toSet().toList()..sort();
+    final out = Uint8List(20 + normalizedAvailable.length);
+    out[0] = _swarmMagic;
+    out[1] = _swarmKindAvailability;
+    out[2] = _encodeMediaType(mediaType);
+    _writeSessionId(out, 3, sessionId);
+    _writeKey6(out, 7, requesterKey6);
+    _writeKey6(out, 13, responderKey6);
+    out[19] = normalizedAvailable.length;
+    for (var i = 0; i < normalizedAvailable.length; i++) {
+      out[20 + i] = normalizedAvailable[i];
+    }
+    return out;
+  }
+
+  static MediaSwarmAvailability? tryParseBinary(Uint8List payload) {
+    if (payload.length < 20 ||
+        payload[0] != _swarmMagic ||
+        payload[1] != _swarmKindAvailability) {
+      return null;
+    }
+
+    final mediaType = _decodeMediaType(payload[2]);
+    if (mediaType == null) return null;
+
+    final availableCount = payload[19];
+    if (payload.length != 20 + availableCount) {
+      return null;
+    }
+
+    return MediaSwarmAvailability(
+      mediaType: mediaType,
+      sessionId: _readSessionId(payload, 3),
+      requesterKey6: _readKey6(payload, 7),
+      responderKey6: _readKey6(payload, 13),
+      availableIndices: payload.sublist(20),
+    );
+  }
+}
+
+int _encodeMediaType(String mediaType) {
+  return switch (mediaType) {
+    'voice' => 0x01,
+    'image' => 0x02,
+    _ => throw ArgumentError.value(mediaType, 'mediaType'),
+  };
+}
+
+String? _decodeMediaType(int raw) {
+  return switch (raw) {
+    0x01 => 'voice',
+    0x02 => 'image',
+    _ => null,
+  };
+}
+
+void _writeSessionId(Uint8List out, int offset, String sessionId) {
+  if (!RegExp(r'^[0-9a-fA-F]{8}$').hasMatch(sessionId)) {
+    throw ArgumentError.value(sessionId, 'sessionId', 'Expected 8 hex chars');
+  }
+  for (var i = 0; i < 4; i++) {
+    out[offset + i] = int.parse(
+      sessionId.substring(i * 2, i * 2 + 2),
+      radix: 16,
+    );
+  }
+}
+
+String _readSessionId(Uint8List payload, int offset) {
+  return payload
+      .sublist(offset, offset + 4)
+      .map((b) => b.toRadixString(16).padLeft(2, '0'))
+      .join();
+}
+
+void _writeKey6(Uint8List out, int offset, String key6) {
+  if (!RegExp(r'^[0-9a-fA-F]{12}$').hasMatch(key6)) {
+    throw ArgumentError.value(key6, 'key6', 'Expected 12 hex chars');
+  }
+  for (var i = 0; i < 6; i++) {
+    out[offset + i] = int.parse(key6.substring(i * 2, i * 2 + 2), radix: 16);
+  }
+}
+
+String _readKey6(Uint8List payload, int offset) {
+  return payload
+      .sublist(offset, offset + 6)
+      .map((b) => b.toRadixString(16).padLeft(2, '0'))
+      .join();
+}