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// Copyright 2018 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package stack
import (
"sync"
"golang.org/x/time/rate"
)
const (
// icmpLimit is the default maximum number of ICMP messages permitted by this
// rate limiter.
icmpLimit = 1000
// icmpBurst is the default number of ICMP messages that can be sent in a single
// burst.
icmpBurst = 50
)
// ICMPRateLimiter is a global rate limiter that controls the generation of
// ICMP messages generated by the stack.
type ICMPRateLimiter struct {
mu sync.RWMutex
l *rate.Limiter
}
// NewICMPRateLimiter returns a global rate limiter for controlling the rate
// at which ICMP messages are generated by the stack.
func NewICMPRateLimiter() *ICMPRateLimiter {
return &ICMPRateLimiter{l: rate.NewLimiter(icmpLimit, icmpBurst)}
}
// Allow returns true if we are allowed to send at least 1 message at the
// moment.
func (i *ICMPRateLimiter) Allow() bool {
i.mu.RLock()
allow := i.l.Allow()
i.mu.RUnlock()
return allow
}
// Limit returns the maximum number of ICMP messages that can be sent in one
// second.
func (i *ICMPRateLimiter) Limit() rate.Limit {
i.mu.RLock()
defer i.mu.RUnlock()
return i.l.Limit()
}
// SetLimit sets the maximum number of ICMP messages that can be sent in one
// second.
func (i *ICMPRateLimiter) SetLimit(newLimit rate.Limit) {
i.mu.RLock()
defer i.mu.RUnlock()
i.l.SetLimit(newLimit)
}
// Burst returns how many ICMP messages can be sent at any single instant.
func (i *ICMPRateLimiter) Burst() int {
i.mu.RLock()
defer i.mu.RUnlock()
return i.l.Burst()
}
// SetBurst sets the maximum number of ICMP messages allowed at any single
// instant.
//
// NOTE: Changing Burst causes the underlying rate limiter to be recreated.
func (i *ICMPRateLimiter) SetBurst(burst int) {
i.mu.Lock()
i.l = rate.NewLimiter(i.l.Limit(), burst)
i.mu.Unlock()
}
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