mirror of https://github.com/ergochat/ergo.git
56 lines
1.2 KiB
Go
56 lines
1.2 KiB
Go
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// Copyright (c) 2019 Shivaram Lingamneni <slingamn@cs.stanford.edu>
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// released under the MIT license
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package connection_limits
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import (
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"errors"
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"sync"
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"time"
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)
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var (
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ErrLimitExceeded = errors.New("too many concurrent connections")
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ErrThrottleExceeded = errors.New("too many recent connection attempts")
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)
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// TorLimiter is a combined limiter and throttler for use on connections
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// proxied from a Tor hidden service (so we don't have meaningful IPs,
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// a notion of CIDR width, etc.)
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type TorLimiter struct {
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sync.Mutex
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numConnections int
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maxConnections int
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throttle GenericThrottle
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}
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func (tl *TorLimiter) Configure(maxConnections int, duration time.Duration, maxConnectionsPerDuration int) {
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tl.Lock()
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defer tl.Unlock()
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tl.maxConnections = maxConnections
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tl.throttle.Duration = duration
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tl.throttle.Limit = maxConnectionsPerDuration
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}
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func (tl *TorLimiter) AddClient() error {
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tl.Lock()
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defer tl.Unlock()
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if tl.maxConnections != 0 && tl.maxConnections <= tl.numConnections {
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return ErrLimitExceeded
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}
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throttled, _ := tl.throttle.Touch()
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if throttled {
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return ErrThrottleExceeded
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}
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tl.numConnections += 1
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return nil
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}
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func (tl *TorLimiter) RemoveClient() {
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tl.Lock()
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tl.numConnections -= 1
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tl.Unlock()
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}
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