TCP Socket - Connection reset while receiving data

[Santoshramani]

Description

I have TCP socket to receive IP camera stream(Playback data) via NVR. Implementation of data read from socket was working fine in xamarin native build but now in dotnet 8 build as soon as app starts receiving data from socket connection getting reset as seen in pcap.
My finding is this is because of socket buffer size is 2kb(as per mSocket.ReceiveBufferSize returns) only.
Also setting expected receive buffer size to socket does't helping.

Reproduction Steps

Create bulk data reading socket using dotnet 8 SDK for android project.

Expected behavior

Socket should not reset connection when transferring bulk data.

Actual behavior

Socket connection getting reset when transferring bulk data.

Regression?

Socket was working fine for bulk data in xamarin native build.

Known Workarounds

Increasing receive buffer size of socket may help.

Configuration

.NET SDK:
 Version:           8.0.401
 Commit:            811edcc344
 Workload version:  8.0.400-manifests.56cd0383
 MSBuild version:   17.11.4+37eb419ad

Runtime Environment:
 OS Name:     Mac OS X
 OS Version:  14.6
 OS Platform: Darwin
 RID:         osx-arm64
 Base Path:   /usr/local/share/dotnet/sdk/8.0.401/

.NET workloads installed:
Configured to use loose manifests when installing new manifests.
 [ios]
   Installation Source: SDK 8.0.400
   Manifest Version:    17.5.8020/8.0.100
   Manifest Path:       /usr/local/share/dotnet/sdk-manifests/8.0.100/microsoft.net.sdk.ios/17.5.8020/WorkloadManifest.json
   Install Type:        FileBased

 [android]
   Installation Source: SDK 8.0.400
   Manifest Version:    34.0.113/8.0.100
   Manifest Path:       /usr/local/share/dotnet/sdk-manifests/8.0.100/microsoft.net.sdk.android/34.0.113/WorkloadManifest.json
   Install Type:        FileBased


Host:
  Version:      8.0.8
  Architecture: arm64
  Commit:       08338fcaa5

.NET SDKs installed:
  8.0.303 [/usr/local/share/dotnet/sdk]
  8.0.401 [/usr/local/share/dotnet/sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.App 6.0.32 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 7.0.20 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 8.0.0 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 8.0.7 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 8.0.8 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 6.0.32 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 7.0.20 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 8.0.0 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 8.0.7 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 8.0.8 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]

Other architectures found:
  None

Environment variables:
  Not set

global.json file:
  Not found

Other information

No response

[Santoshramani]

@karelz @vitek-karas @akoeplinger please look into this issue.

[rzikm]

@Santoshramani Please don't tag individual people. The bot takes care of notifying the right team.

My finding is this is because of socket buffer size is 2kb(as per mSocket.ReceiveBufferSize returns) only.

How do you know this? Does increasing the receive buffer size reliably resolve the issue?

in dotnet 8 build as soon as app starts receiving data from socket connection getting reset as seen in pcap.

Is the socket being reset by the remote peer (the camera?) or locally (by the application)? Can you share the network captures for us to investigate?

[Santoshramani]

@rzikm

Please don't tag individual people. The bot takes care of notifying the right team.

I need solution as soon as possible that's why i've tagged them, because i've to upload my app to playstore as soon as possible due to their policies.

How do you know this? Does increasing the receive buffer size reliably resolve the issue?

Yes i've tried increasing receive buffer size but that doesn't had any effect in performance.

Is the socket being reset by the remote peer (the camera?) or locally (by the application)? Can you share the network captures for us to investigate?

Socket is being reset by the application.
Sorry i can't share pcap as i don't have it now but When socket gets reset at that time packet just before reset is 'TCP Window Full'.

[vitek-karas]

Could you please try this with .NET 9 RC 1 - it's very possible we fixed it there - #104726.

[Santoshramani]

@vitek-karas Yes i've already tried using SDK 9 RC 1 but also not working with it.

[vitek-karas]

/cc @simonrozsival

[simonrozsival]

@Santoshramani hi! would you be able to create a repro project? I'm not able to reproduce this issue on my end based on the issue description.

[wfurt]

note that the socket buffer size should not impact the behavior. When it is getting full it will shrink TCP windows size. Also is there SSL involved or was this only plain socket? And if you use async mace cure you handle cases when the read is finished synchronously - something that did not happen (often) with older .NET releases.