Merge pull request #139 from KomodoPlatform/fix/binance-geo-restrictions

fix(market-metrics): add support for fallback URLs for Binance geo-blocking

packages/komodo_cex_market_data/lib/src/binance/data/binance_provider.dart

@@ -54,6 +54,7 @@ class BinanceProvider {
     int? startUnixTimestampMilliseconds,
     int? endUnixTimestampMilliseconds,
     int? limit,
+    String? baseUrl,
   }) async {
     final queryParameters = <String, dynamic>{
       'symbol': symbol,
@@ -65,8 +66,9 @@ class BinanceProvider {
       if (limit != null) 'limit': limit.toString(),
     };
 
-    final uri =
-        Uri.parse('$apiUrl/klines').replace(queryParameters: queryParameters);
+    final baseRequestUrl = baseUrl ?? apiUrl;
+    final uri = Uri.parse('$baseRequestUrl/klines')
+        .replace(queryParameters: queryParameters);
 
     final response = await http.get(uri);
     if (response.statusCode == 200) {
@@ -84,10 +86,11 @@ class BinanceProvider {
   ///
   /// Returns a [Future] that resolves to a [BinanceExchangeInfoResponse] object
   /// Throws an [Exception] if the request fails.
-  Future<BinanceExchangeInfoResponse> fetchExchangeInfo() async {
-    final response = await http.get(
-      Uri.parse('$apiUrl/exchangeInfo'),
-    );
+  Future<BinanceExchangeInfoResponse> fetchExchangeInfo({
+    String? baseUrl,
+  }) async {
+    final requestUrl = baseUrl ?? apiUrl;
+    final response = await http.get(Uri.parse('$requestUrl/exchangeInfo'));
 
     if (response.statusCode == 200) {
       return BinanceExchangeInfoResponse.fromJson(
@@ -105,15 +108,23 @@ class BinanceProvider {
   /// Returns a [Future] that resolves to a [BinanceExchangeInfoResponseReduced]
   /// object.
   /// Throws an [Exception] if the request fails.
-  Future<BinanceExchangeInfoResponseReduced> fetchExchangeInfoReduced() async {
-    final response = await http.get(
-      Uri.parse('$apiUrl/exchangeInfo'),
-    );
+  Future<BinanceExchangeInfoResponseReduced> fetchExchangeInfoReduced({
+    String? baseUrl,
+  }) async {
+    final requestUrl = baseUrl ?? apiUrl;
+    final response = await http.get(Uri.parse('$requestUrl/exchangeInfo'));
 
     if (response.statusCode == 200) {
       return BinanceExchangeInfoResponseReduced.fromJson(
         jsonDecode(response.body) as Map<String, dynamic>,
       );
+    } else if (response.statusCode == 451) {
+      // service unavailable for legal reasons
+      return BinanceExchangeInfoResponseReduced(
+        timezone: '',
+        serverTime: 0,
+        symbols: List.empty(),
+      );
     } else {
       throw http.ClientException(
         'Failed to load exchange info: ${response.statusCode} ${response.body}',

packages/komodo_cex_market_data/lib/src/binance/data/binance_repository.dart

@@ -1,12 +1,14 @@
 // Using relative imports in this "package" to make it easier to track external
 // dependencies when moving or copying this "package" to another project.
 import 'package:komodo_cex_market_data/src/binance/data/binance_provider.dart';
+import 'package:komodo_cex_market_data/src/binance/models/binance_exchange_info_reduced.dart';
 import 'package:komodo_cex_market_data/src/cex_repository.dart';
 import 'package:komodo_cex_market_data/src/models/models.dart';
 
 // Declaring constants here to make this easier to copy & move around
 /// The base URL for the Binance API.
-String get binanceApiEndpoint => 'https://api.binance.com/api/v3';
+List<String> get binanceApiEndpoint =>
+    ['https://api.binance.com/api/v3', 'https://api.binance.us/api/v3'];
 
 BinanceRepository binanceRepository = BinanceRepository(
   binanceProvider: const BinanceProvider(),
@@ -29,31 +31,32 @@ class BinanceRepository implements CexRepository {
       return _cachedCoinsList!;
     }
 
-    final exchangeInfo = await _binanceProvider.fetchExchangeInfoReduced();
-
-    final coins = <String, CexCoin>{};
-    for (final symbol in exchangeInfo.symbols) {
-      final baseAsset = symbol.baseAsset;
-      final quoteAsset = symbol.quoteAsset;
+    try {
+      return await _executeWithRetry((String baseUrl) async {
+        final exchangeInfo =
+            await _binanceProvider.fetchExchangeInfoReduced(baseUrl: baseUrl);
+        _cachedCoinsList = _convertSymbolsToCoins(exchangeInfo);
+        return _cachedCoinsList!;
+      });
+    } catch (e) {
+      _cachedCoinsList = List.empty();
+    }
 
-      // TODO(Anon): Decide if this belongs at the repository level considering
-      // that the repository should provide and transform data as required
-      // without implementing business logic (or make it an optional parameter).
-      if (!symbol.isSpotTradingAllowed) {
-        continue;
-      }
+    return _cachedCoinsList!;
+  }
 
-      if (!coins.containsKey(baseAsset)) {
-        coins[baseAsset] = _binanceCoin(baseAsset, quoteAsset);
-      } else {
-        coins[baseAsset] = coins[baseAsset]!.copyWith(
-          currencies: {...coins[baseAsset]!.currencies, quoteAsset},
-        );
+  Future<T> _executeWithRetry<T>(Future<T> Function(String) callback) async {
+    for (int i = 0; i < binanceApiEndpoint.length; i++) {
+      try {
+        return await callback(binanceApiEndpoint.elementAt(i));
+      } catch (e) {
+        if (i >= binanceApiEndpoint.length) {
+          rethrow;
+        }
       }
     }
 
-    _cachedCoinsList = coins.values.toList();
-    return _cachedCoinsList!;
+    throw Exception('Invalid state');
   }
 
   CexCoin _binanceCoin(String baseCoinAbbr, String quoteCoinAbbr) {
@@ -83,13 +86,16 @@ class BinanceRepository implements CexRepository {
     final endUnixTimestamp = endAt?.millisecondsSinceEpoch;
     final intervalAbbreviation = interval.toAbbreviation();
 
-    return _binanceProvider.fetchKlines(
-      symbol.toString(),
-      intervalAbbreviation,
-      startUnixTimestampMilliseconds: startUnixTimestamp,
-      endUnixTimestampMilliseconds: endUnixTimestamp,
-      limit: limit,
-    );
+    return await _executeWithRetry((String baseUrl) async {
+      return await _binanceProvider.fetchKlines(
+        symbol.toString(),
+        intervalAbbreviation,
+        startUnixTimestampMilliseconds: startUnixTimestamp,
+        endUnixTimestampMilliseconds: endUnixTimestamp,
+        limit: limit,
+        baseUrl: baseUrl,
+      );
+    });
   }
 
   @override
@@ -166,4 +172,30 @@ class BinanceRepository implements CexRepository {
 
     return result;
   }
+
+  List<CexCoin> _convertSymbolsToCoins(
+    BinanceExchangeInfoResponseReduced exchangeInfo,
+  ) {
+    final coins = <String, CexCoin>{};
+    for (final symbol in exchangeInfo.symbols) {
+      final baseAsset = symbol.baseAsset;
+      final quoteAsset = symbol.quoteAsset;
+
+      // TODO(Anon): Decide if this belongs at the repository level considering
+      // that the repository should provide and transform data as required
+      // without implementing business logic (or make it an optional parameter).
+      if (!symbol.isSpotTradingAllowed) {
+        continue;
+      }
+
+      if (!coins.containsKey(baseAsset)) {
+        coins[baseAsset] = _binanceCoin(baseAsset, quoteAsset);
+      } else {
+        coins[baseAsset] = coins[baseAsset]!.copyWith(
+          currencies: {...coins[baseAsset]!.currencies, quoteAsset},
+        );
+      }
+    }
+    return coins.values.toList();
+  }
 }