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-rw-r--r--p2p/discover/ntp.go32
-rw-r--r--p2p/discover/udp.go25
2 files changed, 39 insertions, 18 deletions
diff --git a/p2p/discover/ntp.go b/p2p/discover/ntp.go
index a87ee1fbe..c1a4b3af1 100644
--- a/p2p/discover/ntp.go
+++ b/p2p/discover/ntp.go
@@ -20,13 +20,20 @@
package discover
import (
+ "fmt"
"net"
"sort"
+ "strings"
"time"
+
+ "github.com/ethereum/go-ethereum/logger"
+ "github.com/ethereum/go-ethereum/logger/glog"
)
-// ntpPool is the NTP server to query for the current time
-const ntpPool = "pool.ntp.org"
+const (
+ ntpPool = "pool.ntp.org" // ntpPool is the NTP server to query for the current time
+ ntpChecks = 3 // Number of measurements to do against the NTP server
+)
// durationSlice attaches the methods of sort.Interface to []time.Duration,
// sorting in increasing order.
@@ -36,6 +43,27 @@ func (s durationSlice) Len() int { return len(s) }
func (s durationSlice) Less(i, j int) bool { return s[i] < s[j] }
func (s durationSlice) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
+// checkClockDrift queries an NTP server for clock drifts and warns the user if
+// one large enough is detected.
+func checkClockDrift() {
+ drift, err := sntpDrift(ntpChecks)
+ if err != nil {
+ return
+ }
+ if drift < -driftThreshold || drift > driftThreshold {
+ warning := fmt.Sprintf("System clock seems off by %v, which can prevent network connectivity", drift)
+ howtofix := fmt.Sprintf("Please enable network time synchronisation in system settings")
+ separator := strings.Repeat("-", len(warning))
+
+ glog.V(logger.Warn).Info(separator)
+ glog.V(logger.Warn).Info(warning)
+ glog.V(logger.Warn).Info(howtofix)
+ glog.V(logger.Warn).Info(separator)
+ } else {
+ glog.V(logger.Debug).Infof("Sanity NTP check reported %v drift, all ok", drift)
+ }
+}
+
// sntpDrift does a naive time resolution against an NTP server and returns the
// measured drift. This method uses the simple version of NTP. It's not precise
// but should be fine for these purposes.
diff --git a/p2p/discover/udp.go b/p2p/discover/udp.go
index fa4bc07dc..03fa0c348 100644
--- a/p2p/discover/udp.go
+++ b/p2p/discover/udp.go
@@ -52,8 +52,9 @@ const (
sendTimeout = 500 * time.Millisecond
expiration = 20 * time.Second
- ntpThreshold = 32 // Continuous timeouts after which to check NTP
- driftThreshold = 10 * time.Second // Allowed clock drift before warning user
+ ntpFailureThreshold = 32 // Continuous timeouts after which to check NTP
+ ntpWarningCooldown = 10 * time.Minute // Minimum amount of time to pass before repeating NTP warning
+ driftThreshold = 10 * time.Second // Allowed clock drift before warning user
)
// RPC packet types
@@ -327,6 +328,7 @@ func (t *udp) loop() {
timeout = time.NewTimer(0)
nextTimeout *pending // head of plist when timeout was last reset
contTimeouts = 0 // number of continuous timeouts to do NTP checks
+ ntpWarnTime = time.Unix(0, 0)
)
<-timeout.C // ignore first timeout
defer timeout.Stop()
@@ -400,20 +402,11 @@ func (t *udp) loop() {
}
}
// If we've accumulated too many timeouts, do an NTP time sync check
- if contTimeouts > ntpThreshold {
- go func() {
- drift, err := sntpDrift(3)
- switch {
- case err != nil:
- glog.V(logger.Warn).Infof("No UDP connectivity, maybe blocked by firewall? (%v)", err)
-
- case drift < -driftThreshold || drift > driftThreshold:
- glog.V(logger.Warn).Infof("System clock seems off by %v, which can prevent network connectivity", drift)
-
- default:
- glog.V(logger.Debug).Infof("Sanity NTP check reported %v drift, all ok", drift)
- }
- }()
+ if contTimeouts > ntpFailureThreshold {
+ if time.Since(ntpWarnTime) >= ntpWarningCooldown {
+ ntpWarnTime = time.Now()
+ go checkClockDrift()
+ }
contTimeouts = 0
}
}