support proxy http2 (#388)(#51)

lib/network/util/byte_buf.dart

@@ -45,10 +45,16 @@ class ByteBuf {
   void clear() {
     readerIndex = 0;
     writerIndex = 0;
+    _buffer = Uint8List(0);
   }
 
   ///释放已读的空间
   void clearRead() {
+    if (readerIndex == writerIndex) {
+      clear();
+      return;
+    }
+
     if (readerIndex > 0) {
       _buffer = Uint8List.sublistView(_buffer, readerIndex, writerIndex);
       writerIndex -= readerIndex;

lib/network/util/byte_utils.dart

@@ -0,0 +1,53 @@
+import 'dart:typed_data';
+
+List<int> viewOrSublist(List<int> data, int offset, int length) {
+  if (data is Uint8List) {
+    return Uint8List.view(data.buffer, data.offsetInBytes + offset, length);
+  } else {
+    return data.sublist(offset, offset + length);
+  }
+}
+
+int readInt64(List<int> bytes, int offset) {
+  var high = readInt32(bytes, offset);
+  var low = readInt32(bytes, offset + 4);
+  return high << 32 | low;
+}
+
+int readInt32(List<int> bytes, int offset) {
+  return (bytes[offset] << 24) |
+      (bytes[offset + 1] << 16) |
+      (bytes[offset + 2] << 8) |
+      bytes[offset + 3];
+}
+
+int readInt24(List<int> bytes, int offset) {
+  return (bytes[offset] << 16) | (bytes[offset + 1] << 8) | bytes[offset + 2];
+}
+
+int readInt16(List<int> bytes, int offset) {
+  return (bytes[offset] << 8) | bytes[offset + 1];
+}
+
+void setInt64(List<int> bytes, int offset, int value) {
+  setInt32(bytes, offset, value >> 32);
+  setInt32(bytes, offset + 4, value & 0xffffffff);
+}
+
+void setInt32(List<int> bytes, int offset, int value) {
+  bytes[offset] = (value >> 24) & 0xff;
+  bytes[offset + 1] = (value >> 16) & 0xff;
+  bytes[offset + 2] = (value >> 8) & 0xff;
+  bytes[offset + 3] = value & 0xff;
+}
+
+void setInt24(List<int> bytes, int offset, int value) {
+  bytes[offset] = (value >> 16) & 0xff;
+  bytes[offset + 1] = (value >> 8) & 0xff;
+  bytes[offset + 2] = value & 0xff;
+}
+
+void setInt16(List<int> bytes, int offset, int value) {
+  bytes[offset] = (value >> 8) & 0xff;
+  bytes[offset + 1] = value & 0xff;
+}

lib/network/util/proxy_helper.dart

@@ -113,10 +113,13 @@ class ProxyHelper {
       request.uri = hostAndPort.domain;
     }
 
-    request.response = HttpResponse(status)
-      ..headers.contentType = 'text/plain'
-      ..headers.contentLength = message.codeUnits.length
-      ..body = message.codeUnits;
+    if (request.response == null || request.method == HttpMethod.connect) {
+      request.response = HttpResponse(status)
+        ..headers.contentType = 'text/plain'
+        ..headers.contentLength = message.codeUnits.length
+        ..body = message.codeUnits;
+    }
+
     request.response?.request = request;
 
     channelContext.host = hostAndPort;