Disable SO_REUSEADDR in wasmtime serve
#7863
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pchickey
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Feb 5, 2024
alexcrichton
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Jun 3, 2024
This effectively reverts bytecodealliance#7863 which was a misunderstanding on my part about `SO_REUSEADDR`. I think I mixed it up with `SO_REUSEPORT`. Without `SO_REUSEADDR` it's possible to have this happen: * Start a `wasmtime serve` session * Connect to the session with `nc` * Kill the server * Restarting the server no longer works Due to the active TCP connection at the time the server was killed the socket/address is in the `TIME_WAIT` state which apparently prevents rebinding the port until the OS has a chance to clean up everything. Setting `SO_REUSEADDR` enables rebinding the address quickly. Now in bytecodealliance#7863 that was trying to fix bytecodealliance#7852 which said that it was possible to have multiple `wasmtime serve` instances binding the same port. That can lead to confusion and is generally something we don't want. That being said bytecodealliance#7863 didn't actually change anything on either macOS or Unix, so the issue may not be fixed. This PR additionally adds two new tests, both for rebinding an in-use port quickly and additionally ensuring the same port can't be listened to twice. prtest:full
alexcrichton
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Jun 3, 2024
This reverts part of bytecodealliance#7863 which was a misunderstanding on my part about `SO_REUSEADDR`. I think I mixed it up with `SO_REUSEPORT`. Without `SO_REUSEADDR` it's possible to have this happen on Unix: * Start a `wasmtime serve` session * Connect to the session with `nc` * Kill the server * Restarting the server no longer works Due to the active TCP connection at the time the server was killed the socket/address is in the `TIME_WAIT` state which apparently prevents rebinding the port until the OS has a chance to clean up everything. Setting `SO_REUSEADDR` enables rebinding the address quickly. Now in bytecodealliance#7863 that was trying to fix bytecodealliance#7852 which said that it was possible to have multiple `wasmtime serve` instances binding the same port. That can lead to confusion and is generally something we don't want. That being said bytecodealliance#7863 only fixed the issue for Windows but ended up making Unix worse. This PR restores more reasonable behavior for both Unix and Windows by conditionally setting the `SO_REUSEADDR` based on the platform. This PR additionally adds two new tests, both for rebinding an in-use port quickly and additionally ensuring the same port can't be listened to twice.
alexcrichton
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Jun 3, 2024
This reverts part of bytecodealliance#7863 which was a misunderstanding on my part about `SO_REUSEADDR`. I think I mixed it up with `SO_REUSEPORT`. Without `SO_REUSEADDR` it's possible to have this happen on Unix: * Start a `wasmtime serve` session * Connect to the session with `nc` * Kill the server * Restarting the server no longer works Due to the active TCP connection at the time the server was killed the socket/address is in the `TIME_WAIT` state which apparently prevents rebinding the port until the OS has a chance to clean up everything. Setting `SO_REUSEADDR` enables rebinding the address quickly. Now in bytecodealliance#7863 that was trying to fix bytecodealliance#7852 which said that it was possible to have multiple `wasmtime serve` instances binding the same port. That can lead to confusion and is generally something we don't want. That being said bytecodealliance#7863 only fixed the issue for Windows but ended up making Unix worse. This PR restores more reasonable behavior for both Unix and Windows by conditionally setting the `SO_REUSEADDR` based on the platform. This PR additionally adds two new tests, both for rebinding an in-use port quickly and additionally ensuring the same port can't be listened to twice.
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Jun 3, 2024
This reverts part of #7863 which was a misunderstanding on my part about `SO_REUSEADDR`. I think I mixed it up with `SO_REUSEPORT`. Without `SO_REUSEADDR` it's possible to have this happen on Unix: * Start a `wasmtime serve` session * Connect to the session with `nc` * Kill the server * Restarting the server no longer works Due to the active TCP connection at the time the server was killed the socket/address is in the `TIME_WAIT` state which apparently prevents rebinding the port until the OS has a chance to clean up everything. Setting `SO_REUSEADDR` enables rebinding the address quickly. Now in #7863 that was trying to fix #7852 which said that it was possible to have multiple `wasmtime serve` instances binding the same port. That can lead to confusion and is generally something we don't want. That being said #7863 only fixed the issue for Windows but ended up making Unix worse. This PR restores more reasonable behavior for both Unix and Windows by conditionally setting the `SO_REUSEADDR` based on the platform. This PR additionally adds two new tests, both for rebinding an in-use port quickly and additionally ensuring the same port can't be listened to twice.
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Closes #7852