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-rw-r--r--pkg/tcpip/header/ipv4.go10
1 files changed, 7 insertions, 3 deletions
diff --git a/pkg/tcpip/header/ipv4.go b/pkg/tcpip/header/ipv4.go
index 2be21ec75..6a8db84d6 100644
--- a/pkg/tcpip/header/ipv4.go
+++ b/pkg/tcpip/header/ipv4.go
@@ -17,6 +17,7 @@ package header
import (
"encoding/binary"
"fmt"
+ "time"
"gvisor.dev/gvisor/pkg/tcpip"
)
@@ -813,9 +814,12 @@ const (
// ipv4TimestampTime provides the current time as specified in RFC 791.
func ipv4TimestampTime(clock tcpip.Clock) uint32 {
- const millisecondsPerDay = 24 * 3600 * 1000
- const nanoPerMilli = 1000000
- return uint32((clock.NowNanoseconds() / nanoPerMilli) % millisecondsPerDay)
+ // Per RFC 791 page 21:
+ // The Timestamp is a right-justified, 32-bit timestamp in
+ // milliseconds since midnight UT.
+ now := clock.Now().UTC()
+ midnight := now.Truncate(24 * time.Hour)
+ return uint32(now.Sub(midnight).Milliseconds())
}
// IP Timestamp option fields.