Unix: fix UDP ReuseAddress with non .NET Core UDP clients #32046

tmds · 2018-08-31T12:37:19Z

Fixes #32027

.NET Core sets SO_REUSEPORT to enable reusing the address with other
sockets. This works when the other sockets also set SO_REUSEPORT.

SO_REUSEADDR can also be used for this. When one application uses
SO_REUSEADDR and another uses SO_REUSEPORT, the second application
will fail to bind.

To implement SocketOptionName.ReuseAddress we need to set both options.
This enables sharing with applications that set SO_REUSEPORT,
SO_REUSEADDR or both.

.NET Core sets SO_REUSEPORT to enable reusing the address with other sockets. This works when the other sockets also set SO_REUSEPORT. SO_REUSEADDR can also be used for this. When one application uses SO_REUSEADDR and another uses SO_REUSEPORT, the second application will fail to bind. To implement SocketOptionName.ReuseAddress we need to set both options. This enables sharing with applications that set SO_REUSEPORT, SO_REUSEADDR or both.

tmds · 2018-08-31T12:38:12Z

Fixes https://github.com/dotnet/corefx/issues/32027
This is a regression in 2.1 caused by #24809.

danmoseley · 2018-09-02T05:38:31Z

src/Native/Unix/System.Native/pal_networking.c

@@ -1842,7 +1840,15 @@ SystemNative_SetSockOpt(intptr_t socket, int32_t socketOptionLevel, int32_t sock
                }
            }

+            // An application that sets SO_REUSEPORT/SO_REUSEADDR can share the with another application


share the .. ?

"endpoint", pushed a commit to fix this.

tmds · 2018-09-04T21:23:09Z

I want to take another look at this. We may want to not set SO_REUSEPORT for UDP on Linux because that will load balance datagrams. We may still want to set it for TCP.
No need to review yet.

tmds · 2018-09-07T10:12:31Z

I looked a bit further into the finer details.

Typical use-cases work as expected: reuse TCP listen port, share UDP multicast.

One case behaves a bit special on Linux: UDP sockets with ReuseAddress set will distribute unicast datagrams accross the different sockets. On Windows/BSD, the last socket that binds 'steals' the port. We can avoid this by not setting SO_REUSEPORT (and only SO_REUSEADDR).

It would be nicest if Linux can stay close to the Windows semantics. On the other hand, the implementation will make the code a bit messier (special case for UDP on Linux). Maybe the behavior is good enough and we want to wait until someone considers&reports this as an issue.

stephentoub · 2018-09-24T17:42:02Z

Maybe the behavior is good enough and we want to wait until someone considers&reports this as an issue.

That sounds fine to me.

stephentoub · 2018-09-25T00:19:22Z

Thanks, @tmds. Let's leave it as-is for now to avoid unnecessary churn.

tmds · 2018-09-25T11:23:09Z

@stephentoub my comment was about adding additional changes to this PR. The PR in its current state has changes which are necessary to fix https://github.com/dotnet/corefx/issues/32027.

stephentoub

Can you add a test for this (ideally for all of the modes called out)? From the description of the issue being addressed, it seems like it should be feasible to do. Given the subtleties here, it'll be good to verify that, for example, we get consistent behavior across Linux and macOS.

Otherwise, LGTM.

stephentoub · 2018-10-02T19:42:14Z

macOS is unhappy with the new test:

Unhandled Exception of Type System.Net.Sockets.SocketException
Message :
System.Net.Sockets.SocketException : Address already in use
Stack Trace :
   at System.Net.Sockets.Socket.UpdateStatusAfterSocketErrorAndThrowException(SocketError error, String callerName) in /Users/dotnet-bot/j/workspace/dotnet_corefx/master/osx-TGroup_netcoreapp+CGroup_Debug+AGroup_x64+TestOuter_false_prtest/src/System.Net.Sockets/src/System/Net/Sockets/Socket.cs:line 5153
   at System.Net.Sockets.Socket.DoBind(EndPoint endPointSnapshot, SocketAddress socketAddress) in /Users/dotnet-bot/j/workspace/dotnet_corefx/master/osx-TGroup_netcoreapp+CGroup_Debug+AGroup_x64+TestOuter_false_prtest/src/System.Net.Sockets/src/System/Net/Sockets/Socket.cs:line 761
   at System.Net.Sockets.Socket.Bind(EndPoint localEP) in /Users/dotnet-bot/j/workspace/dotnet_corefx/master/osx-TGroup_netcoreapp+CGroup_Debug+AGroup_x64+TestOuter_false_prtest/src/System.Net.Sockets/src/System/Net/Sockets/Socket.cs:line 702
   at System.Net.Sockets.Tests.SocketOptionNameTest.ReuseAddressUdp() in /Users/dotnet-bot/j/workspace/dotnet_corefx/master/osx-TGroup_netcoreapp+CGroup_Debug+AGroup_x64+TestOuter_false_prtest/src/System.Net.Sockets/tests/FunctionalTests/SocketOptionNameTest.cs:line 523

tmds · 2018-10-03T09:07:52Z

@dotnet-bot test Linux x64 Release Build please

tmds · 2018-10-03T09:09:28Z

macOS is unhappy with the new test:

Due to BSD vs Linux differences. I've updated the test.

stephentoub · 2018-10-03T10:21:13Z

src/System.Net.Sockets/tests/FunctionalTests/SocketOptionNameTest.cs

@@ -490,6 +490,45 @@ public void ExclusiveAddressUseTcp()
            }
        }

+        [DllImport("libc", SetLastError = true)]
+        private unsafe static extern int setsockopt(int socket, int level, int option_name, void* option_value, uint option_len);


Other places we add Unix-specific DllImports like this to tests, we separated them out into their own, e.g., SocketOptionNameTest.Unix.cs partial file. IIRC, it was because of issues they'd otherwise cause on .NET Native when running tests, though I don't remember for sure. Regardless, can you move this one to be consistent?

stephentoub · 2018-10-03T15:13:58Z

error CS0103: The name 'setsockopt' does not exist in the current context

tmds · 2018-10-04T07:42:31Z

error CS0103: The name 'setsockopt' does not exist in the current context

It looks like the SocketOptionNameTest.Unix.cs isn't included in the project. I thought it might be because I had to update the csproj Configurations with separate Unix and Windows, but it still fails when I build it. I don't know what I'm missing.

tmds · 2018-10-09T06:45:41Z

@dotnet-bot test NETFX x86 Release Build please
@dotnet-bot test Packaging All Configurations x64 Debug Build please
@dotnet-bot test UWP CoreCLR x64 Debug Build please
@dotnet-bot test UWP CoreCLR x64 Release Build please

tmds · 2018-10-09T06:46:07Z

@dotnet-bot test UWP NETNative x86 Release Build please

tmds · 2018-10-09T08:19:08Z

CI approves. This should be good to merge.

stephentoub

Thanks.

…efx#32046) * Unix: fix UDP ReuseAddress with non .NET Core UDP clients .NET Core sets SO_REUSEPORT to enable reusing the address with other sockets. This works when the other sockets also set SO_REUSEPORT. SO_REUSEADDR can also be used for this. When one application uses SO_REUSEADDR and another uses SO_REUSEPORT, the second application will fail to bind. To implement SocketOptionName.ReuseAddress we need to set both options. This enables sharing with applications that set SO_REUSEPORT, SO_REUSEADDR or both. * Fix comment * wording: share -> reuse * Add test * Fix test on mac * Move DllImport to separate file * Add separate csproj Configurations for Windows and Unix * Add Windows and Unix to Configurations.props Commit migrated from dotnet/corefx@0ec9c9d

danmoseley reviewed Sep 2, 2018

View reviewed changes

Fix comment

bb1b070

karelz added the area-System.Net label Sep 4, 2018

karelz requested a review from a team September 4, 2018 17:06

karelz assigned tmds, rmkerr, davidsh, caesar-chen and wfurt Sep 4, 2018

davidsh added area-System.Net.Sockets os-linux Linux OS (any supported distro) and removed area-System.Net labels Sep 4, 2018

karelz approved these changes Sep 4, 2018

View reviewed changes

tmds changed the title ~~Unix: fix UDP ReuseAddress with non .NET Core UDP clients~~ [WIP]Unix: fix UDP ReuseAddress with non .NET Core UDP clients Sep 4, 2018

karelz added this to the 3.0 milestone Sep 6, 2018

wording: share -> reuse

9a02fc4

tmds changed the title ~~[WIP]Unix: fix UDP ReuseAddress with non .NET Core UDP clients~~ Unix: fix UDP ReuseAddress with non .NET Core UDP clients Sep 7, 2018

stephentoub closed this Sep 25, 2018

stephentoub reopened this Sep 25, 2018

stephentoub approved these changes Sep 25, 2018

View reviewed changes

Add test

06fac22

Fix test on mac

6268d07

stephentoub reviewed Oct 3, 2018

View reviewed changes

Move DllImport to separate file

23d4107

Add separate csproj Configurations for Windows and Unix

e4a0e88

Add Windows and Unix to Configurations.props

e9db29f

stephentoub approved these changes Oct 9, 2018

View reviewed changes

stephentoub merged commit 0ec9c9d into dotnet:master Oct 9, 2018

QTimort mentioned this pull request Oct 30, 2018

Spike: SocketException: Address already in use when running on Ubuntu richardschneider/net-mdns#22

Closed

yuezengms mentioned this pull request Feb 1, 2020

Address "System.Net.Sockets.SocketException: Address already in use" on K8S/Linux using HttpClient/TCP dotnet/runtime#29327

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Unix: fix UDP ReuseAddress with non .NET Core UDP clients #32046

Unix: fix UDP ReuseAddress with non .NET Core UDP clients #32046

tmds commented Aug 31, 2018 •

edited by karelz

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Unix: fix UDP ReuseAddress with non .NET Core UDP clients #32046

Unix: fix UDP ReuseAddress with non .NET Core UDP clients #32046

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