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Seed RNG to ensure different ICMP ids. #638

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Jun 15, 2020
+3 −2
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Seed RNG to ensure different ICMP ids. #638

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5 changes: 3 additions & 2 deletions prober/icmp.go
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Original file line number Diff line number Diff line change
Expand Up @@ -39,19 +39,20 @@ var (
)

func init() {
r := rand.New(rand.NewSource(time.Now().UnixNano()))
// PID is typically 1 when running in a container; in that case, set
// the ICMP echo ID to a random value to avoid potential clashes with
// other blackbox_exporter instances. See #411.
if pid := os.Getpid(); pid == 1 {
icmpID = rand.Intn(1 << 16)
icmpID = r.Intn(1 << 16)
} else {
icmpID = pid & 0xffff
}

// Start the ICMP echo sequence at a random offset to prevent them from
// being in sync when several blackbox_exporter instances are restarted
// at the same time. See #411.
icmpSequence = uint16(rand.Intn(1 << 16))
icmpSequence = uint16(r.Intn(1 << 16))
}

func getICMPSequence() uint16 {
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