mirror of
https://github.com/ergochat/ergo.git
synced 2024-11-14 16:09:32 +01:00
f6d2dade4e
Basically, fakelag was counting the time imposed by its own sleeps as though the user had themselves paused for that amount of time. Therefore, if a user sent a large number of consecutive commands, every other command would pause for the expected throttle interval, but the subsequent command would be processed instantly (you'd get two back-to-back commands). This resulted in throttled users being able to send at double the expected rate.
95 lines
2.5 KiB
Go
95 lines
2.5 KiB
Go
// Copyright (c) 2018 Shivaram Lingamneni <slingamn@cs.stanford.edu>
|
|
// released under the MIT license
|
|
|
|
package irc
|
|
|
|
import (
|
|
"time"
|
|
)
|
|
|
|
// fakelag is a system for artificially delaying commands when a user issues
|
|
// them too rapidly
|
|
|
|
type FakelagState uint
|
|
|
|
const (
|
|
// initially, the client is "bursting" and can send n commands without
|
|
// encountering fakelag
|
|
FakelagBursting FakelagState = iota
|
|
// after that, they're "throttled" and we sleep in between commands until
|
|
// they're spaced sufficiently far apart
|
|
FakelagThrottled
|
|
)
|
|
|
|
// this is intentionally not threadsafe, because it should only be touched
|
|
// from the loop that accepts the client's input and runs commands
|
|
type Fakelag struct {
|
|
window time.Duration
|
|
burstLimit uint
|
|
throttleMessagesPerWindow uint
|
|
cooldown time.Duration
|
|
nowFunc func() time.Time
|
|
sleepFunc func(time.Duration)
|
|
|
|
state FakelagState
|
|
burstCount uint // number of messages sent in the current burst
|
|
lastTouch time.Time
|
|
}
|
|
|
|
func NewFakelag(window time.Duration, burstLimit uint, throttleMessagesPerWindow uint, cooldown time.Duration) *Fakelag {
|
|
return &Fakelag{
|
|
window: window,
|
|
burstLimit: burstLimit,
|
|
throttleMessagesPerWindow: throttleMessagesPerWindow,
|
|
cooldown: cooldown,
|
|
nowFunc: time.Now,
|
|
sleepFunc: time.Sleep,
|
|
state: FakelagBursting,
|
|
}
|
|
}
|
|
|
|
// register a new command, sleep if necessary to delay it
|
|
func (fl *Fakelag) Touch() {
|
|
if fl == nil {
|
|
return
|
|
}
|
|
|
|
now := fl.nowFunc()
|
|
// XXX if lastTouch.IsZero(), treat it as "very far in the past", which is fine
|
|
elapsed := now.Sub(fl.lastTouch)
|
|
fl.lastTouch = now
|
|
|
|
if fl.state == FakelagBursting {
|
|
// determine if the previous burst is over
|
|
if elapsed > fl.cooldown {
|
|
fl.burstCount = 0
|
|
}
|
|
|
|
fl.burstCount++
|
|
if fl.burstCount > fl.burstLimit {
|
|
// reset burst window for next time
|
|
fl.burstCount = 0
|
|
// transition to throttling
|
|
fl.state = FakelagThrottled
|
|
// continue to throttling logic
|
|
} else {
|
|
return
|
|
}
|
|
}
|
|
|
|
if fl.state == FakelagThrottled {
|
|
if elapsed > fl.cooldown {
|
|
// let them burst again
|
|
fl.state = FakelagBursting
|
|
return
|
|
}
|
|
// space them out by at least window/messagesperwindow
|
|
sleepDuration := time.Duration((int64(fl.window) / int64(fl.throttleMessagesPerWindow)) - int64(elapsed))
|
|
if sleepDuration > 0 {
|
|
fl.sleepFunc(sleepDuration)
|
|
// the touch time should take into account the time we slept
|
|
fl.lastTouch = fl.nowFunc()
|
|
}
|
|
}
|
|
}
|