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wgengine/magicsock: add envknob to print information about port selection

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To aid in debugging where a customer has static port-forwards set up and
there are issues establishing a connection through that port.

Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: Ic5558bcdb40c9119b83f79dcacf2233b07777f2a
This commit is contained in:
Andrew Dunham 2023-01-31 13:05:07 -05:00
parent cf8dd7aa09
commit 7393ce5e4f
1 changed files with 13 additions and 0 deletions
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13
wgengine/magicsock/magicsock.go
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@ -3010,6 +3010,8 @@ func (c *Conn) listenPacket(network string, port uint16) (nettype.PacketConn, er
return nettype.MakePacketListenerWithNetIP(netns.Listener(c.logf)).ListenPacket(ctx, network, addr)
}
var debugBindSocket = envknob.RegisterBool("TS_DEBUG_MAGICSOCK_BIND_SOCKET")
// bindSocket initializes rucPtr if necessary and binds a UDP socket to it.
// Network indicates the UDP socket type; it must be "udp4" or "udp6".
// If rucPtr had an existing UDP socket bound, it closes that socket.
@ -3017,6 +3019,10 @@ func (c *Conn) listenPacket(network string, port uint16) (nettype.PacketConn, er
// If curPortFate is set to dropCurrentPort, no attempt is made to reuse
// the current port.
func (c *Conn) bindSocket(ruc *RebindingUDPConn, network string, curPortFate currentPortFate) error {
if debugBindSocket() {
c.logf("magicsock: bindSocket: network=%q curPortFate=%v", network, curPortFate)
}
// Hold the ruc lock the entire time, so that the close+bind is atomic
// from the perspective of ruc receive functions.
ruc.mu.Lock()
@ -3049,6 +3055,10 @@ func (c *Conn) bindSocket(ruc *RebindingUDPConn, network string, curPortFate cur
// Remove duplicates. (All duplicates are consecutive.)
uniq.ModifySlice(&ports)
if debugBindSocket() {
c.logf("magicsock: bindSocket: candidate ports: %+v", ports)
}
var pconn nettype.PacketConn
for _, port := range ports {
// Close the existing conn, in case it is sitting on the port we want.
@ -3064,6 +3074,9 @@ func (c *Conn) bindSocket(ruc *RebindingUDPConn, network string, curPortFate cur
}
trySetSocketBuffer(pconn, c.logf)
// Success.
if debugBindSocket() {
c.logf("magicsock: bindSocket: successfully listened %v port %d", network, port)
}
ruc.setConnLocked(pconn, network)
if network == "udp4" {
health.SetUDP4Unbound(false)