egametang/ET · critical · Exception

recv packet size error, 可能是外网探测端口: {this.packetSize}

Error message

recv packet size error, 可能是外网探测端口: {this.packetSize}

What it means

PacketParser reads a 4-byte inner (server-to-server) packet size and validates it against [Packet.MinPacketSize, ushort.MaxValue*16]. A value outside that range means the stream is not a valid inner protocol frame — the comment suggests an external probe hitting the inner port.

Source

Thrown at Packages/cn.etetet.core/Scripts/Core/Share/Network/PacketParser.cs:50

			{
				switch (this.state)
				{
					case ParserState.PacketSize:
					{
						if (this.service.ServiceType == ServiceType.Inner)
						{
							if (this.buffer.Length < InnerPacketSizeLength)
							{
								memoryBuffer = null;
								return false;
							}

							this.buffer.Read(this.cache, 0, InnerPacketSizeLength);

							this.packetSize = BitConverter.ToInt32(this.cache, 0);
							if (this.packetSize > ushort.MaxValue * 16 || this.packetSize < Packet.MinPacketSize)
							{
								throw new Exception($"recv packet size error, 可能是外网探测端口: {this.packetSize}");
							}
						}
						else
						{
							if (this.buffer.Length < OuterPacketSizeLength)
							{
								memoryBuffer = null;
								return false;
							}

							this.buffer.Read(this.cache, 0, OuterPacketSizeLength);

							this.packetSize = BitConverter.ToUInt16(this.cache, 0);
							if (this.packetSize < Packet.MinPacketSize)
							{
								throw new Exception($"recv packet size error, 可能是外网探测端口: {this.packetSize}");
							}
						}

View on GitHub (pinned to 5cab01f7a8)

Solutions

1. Keep the inner port on a private/trusted network and never expose it publicly.
2. Verify the peer is speaking the inner protocol (auth/handshake) before framing.
3. On error, close/reset the connection rather than crashing the service.

Example fix

// before
if (packetSize > ushort.MaxValue * 16 || packetSize < Packet.MinPacketSize)
    throw new Exception(...);
// after
if (packetSize > ushort.MaxValue * 16 || packetSize < Packet.MinPacketSize) {
    Log.Error($"bad inner frame {packetSize}, likely probing");
    this.service.RemoveChannel(channelId);
    return false;
}

null

static bool IsValidInnerPacketSize(int s) => s >= Packet.MinPacketSize && s <= ushort.MaxValue * 16;

try { if (!parser.Parse(out var mb))) return; }
catch (Exception e) when (e.Message.Contains("recv packet size error"))
{ service.RemoveChannel(channelId); Log.Error(e); }

When it happens

Trigger: An outer/client connection or a port scanner sending bytes to the inner port, a desync after a dropped packet, or two protocols multiplexed on one port.

Common situations: Firewall/health-check probing the inner port, client connecting to the inner port by mistake, or memory corruption in the read buffer.

Related errors

• send packet too large: {stream.Length} {stream.Position}
• TChannel已经被Dispose, 不能发送消息
• socket set buffer error: {this.sendBuffer.First.Length}, {th
• bind error: {ipEndPoint}
• socket error: {e.LastOperation}

AI-assisted analysis of egametang/ET@5cab01f7a8 (2026-08-13). Data as JSON: /api/errors/d4a049ee155b4b04. Report an issue: GitHub.