Brad Fitzpatrick 73280595a8 derp: accept dup clients without closing prior's connection ... A public key should only have max one connection to a given DERP node (or really: one connection to a node in a region). But if people clone their machine keys (e.g. clone their VM, Raspbery Pi SD card, etc), then we can get into a situation where a public key is connected multiple times. Originally, the DERP server handled this by just kicking out a prior connections whenever a new one came. But this led to reconnect fights where 2+ nodes were in hard loops trying to reconnect and kicking out their peer. Then a909d37a59 tried to add rate limiting to how often that dup-kicking can happen, but empirically it just doesn't work and ~leaks a bunch of goroutines and TCP connections, tying them up for hour+ while more and more accumulate and waste memory. Mostly because we were doing a time.Sleep forever while not reading from their TCP connections. Instead, just accept multiple connections per public key but track which is the most recent. And if two both are writing back & forth, then optionally disable them both. That last part is only enabled in tests for now. The current default policy is just last-sender-wins while we gather the next round of stats. Updates #2751 Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>		2021-08-31 08:21:21 -07:00
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derphttp	cmd/derper: mesh over VPC network	2021-07-29 14:08:16 -07:00
testdata	derp: add debug traffic handler	2021-06-18 15:47:55 -07:00
derp_client.go	cmd/derper/derpprobe: add derp prober	2021-07-13 08:30:15 -07:00
derp_server.go	derp: accept dup clients without closing prior's connection	2021-08-31 08:21:21 -07:00
derp_test.go	derp: accept dup clients without closing prior's connection	2021-08-31 08:21:21 -07:00
derp.go	wgengine/magicsock, derp, derp/derphttp: respond to DERP server->client pings	2021-03-09 13:56:13 -08:00
dropreason_string.go	derp: accept dup clients without closing prior's connection	2021-08-31 08:21:21 -07:00