74743ac8ae
* Initial rate limiting * Move rate limiting to client API * Update rate limits to hopefully be self-cleaning * Use X-Forwarded-For, add comments * Reduce rate limit threshold * Tweak interval * Configurable backoff * Review comments, set cleanup interval to 30 seconds * Allow generate-config to produce sane CI config * Fix Complement dockerfile
99 lines
2.6 KiB
Go
99 lines
2.6 KiB
Go
package routing
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import (
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"net/http"
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"sync"
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"time"
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"github.com/matrix-org/dendrite/clientapi/jsonerror"
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"github.com/matrix-org/dendrite/internal/config"
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"github.com/matrix-org/util"
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)
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type rateLimits struct {
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limits map[string]chan struct{}
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limitsMutex sync.RWMutex
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enabled bool
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requestThreshold int64
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cooloffDuration time.Duration
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}
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func newRateLimits(cfg *config.RateLimiting) *rateLimits {
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l := &rateLimits{
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limits: make(map[string]chan struct{}),
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enabled: cfg.Enabled,
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requestThreshold: cfg.Threshold,
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cooloffDuration: time.Duration(cfg.CooloffMS) * time.Millisecond,
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}
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if l.enabled {
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go l.clean()
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}
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return l
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}
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func (l *rateLimits) clean() {
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for {
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// On a 30 second interval, we'll take an exclusive write
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// lock of the entire map and see if any of the channels are
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// empty. If they are then we will close and delete them,
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// freeing up memory.
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time.Sleep(time.Second * 30)
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l.limitsMutex.Lock()
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for k, c := range l.limits {
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if len(c) == 0 {
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close(c)
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delete(l.limits, k)
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}
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}
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l.limitsMutex.Unlock()
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}
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}
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func (l *rateLimits) rateLimit(req *http.Request) *util.JSONResponse {
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// If rate limiting is disabled then do nothing.
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if !l.enabled {
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return nil
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}
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// Lock the map long enough to check for rate limiting. We hold it
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// for longer here than we really need to but it makes sure that we
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// also don't conflict with the cleaner goroutine which might clean
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// up a channel after we have retrieved it otherwise.
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l.limitsMutex.RLock()
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defer l.limitsMutex.RUnlock()
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// First of all, work out if X-Forwarded-For was sent to us. If not
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// then we'll just use the IP address of the caller.
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caller := req.RemoteAddr
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if forwardedFor := req.Header.Get("X-Forwarded-For"); forwardedFor != "" {
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caller = forwardedFor
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}
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// Look up the caller's channel, if they have one. If they don't then
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// let's create one.
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rateLimit, ok := l.limits[caller]
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if !ok {
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l.limits[caller] = make(chan struct{}, l.requestThreshold)
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rateLimit = l.limits[caller]
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}
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// Check if the user has got free resource slots for this request.
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// If they don't then we'll return an error.
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select {
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case rateLimit <- struct{}{}:
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default:
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// We hit the rate limit. Tell the client to back off.
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return &util.JSONResponse{
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Code: http.StatusTooManyRequests,
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JSON: jsonerror.LimitExceeded("You are sending too many requests too quickly!", l.cooloffDuration.Milliseconds()),
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}
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}
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// After the time interval, drain a resource from the rate limiting
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// channel. This will free up space in the channel for new requests.
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go func() {
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<-time.After(l.cooloffDuration)
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<-rateLimit
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}()
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return nil
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}
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