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e107977f75
By default, Windows sets the SIO_UDP_CONNRESET and SIO_UDP_NETRESET options on created UDP sockets. These behaviours make the UDP socket ICMP-aware; when the system gets an ICMP message (e.g. an "ICMP Port Unreachable" message, in the case of SIO_UDP_CONNRESET), it will cause the underlying UDP socket to throw an error. Confusingly, this can occur even on reads, if the same UDP socket is used to write a packet that triggers this response. The Go runtime disabled the SIO_UDP_CONNRESET behavior in 3114bd6, but did not change SIO_UDP_NETRESET–probably because that socket option isn't documented particularly well. Various other networking code seem to disable this behaviour, such as the Godot game engine (godotengine/godot#22332) and the Eclipse TCF agent (link below). Others appear to work around this by ignoring the error returned (anacrolix/dht#16, among others). For now, until it's clear whether this ends up in the upstream Go implementation or not, let's also disable the SIO_UDP_NETRESET in a similar manner to SIO_UDP_CONNRESET. Eclipse TCF agent: https://gitlab.eclipse.org/eclipse/tcf/tcf.agent/-/blob/master/agent/tcf/framework/mdep.c Updates #10976 Updates golang/go#68614 Signed-off-by: Andrew Dunham <andrew@du.nham.ca> Change-Id: I70a2f19855f8dec1bfb82e63f6d14fc4a22ed5c3
59 lines
1.5 KiB
Go
59 lines
1.5 KiB
Go
// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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//go:build windows
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package magicsock
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import (
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"net"
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"unsafe"
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"golang.org/x/sys/windows"
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"tailscale.com/types/logger"
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"tailscale.com/types/nettype"
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)
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func trySetUDPSocketOptions(pconn nettype.PacketConn, logf logger.Logf) {
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c, ok := pconn.(*net.UDPConn)
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if !ok {
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// not a UDP connection; nothing to do
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return
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}
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sysConn, err := c.SyscallConn()
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if err != nil {
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logf("trySetUDPSocketOptions: getting SyscallConn failed: %v", err)
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return
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}
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// Similar to https://github.com/golang/go/issues/5834 (which involved
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// WSAECONNRESET), Windows can return a WSAENETRESET error, even on UDP
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// reads. Disable this.
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const SIO_UDP_NETRESET = windows.IOC_IN | windows.IOC_VENDOR | 15
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var ioctlErr error
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err = sysConn.Control(func(fd uintptr) {
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ret := uint32(0)
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flag := uint32(0)
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size := uint32(unsafe.Sizeof(flag))
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ioctlErr = windows.WSAIoctl(
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windows.Handle(fd),
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SIO_UDP_NETRESET, // iocc
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(*byte)(unsafe.Pointer(&flag)), // inbuf
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size, // cbif
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nil, // outbuf
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0, // cbob
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&ret, // cbbr
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nil, // overlapped
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0, // completionRoutine
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)
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})
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if ioctlErr != nil {
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logf("trySetUDPSocketOptions: could not set SIO_UDP_NETRESET: %v", ioctlErr)
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}
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if err != nil {
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logf("trySetUDPSocketOptions: SyscallConn.Control failed: %v", err)
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}
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}
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