From 8edb74e57276c712444ccfb89ed40dd0ca5c39d6 Mon Sep 17 00:00:00 2001
From: Leonid Bugaev <leonsbox@gmail.com>
Date: Wed, 7 Jul 2021 20:50:47 +0300
Subject: [PATCH] Add support for "go" timestamp source

Windows having issues with generating timestamps, so adding application level timestamp generation
Made small refactoring to move "accurate-enough" time to own package.
---
 capture/capture.go |  8 +++++++-
 simpletime/time.go | 17 +++++++++++++++++
 tcp/tcp_message.go |  5 +++--
 tcp/tcp_packet.go  | 16 ++++------------
 4 files changed, 31 insertions(+), 15 deletions(-)
 create mode 100644 simpletime/time.go

diff --git a/capture/capture.go b/capture/capture.go
index 93fb668..c56e6a4 100644
--- a/capture/capture.go
+++ b/capture/capture.go
@@ -229,9 +229,10 @@ func (l *Listener) PcapHandle(ifi pcap.Interface) (handle *pcap.Handle, err erro
 	}
 	defer inactive.CleanUp()
 
-	if l.TimestampType != "" {
+	if l.TimestampType != "" && l.TimestampType != "go" {
 		var ts pcap.TimestampSource
 		ts, err = pcap.TimestampSourceFromString(l.TimestampType)
+		fmt.Println("Setting custom Timestamp Source. Supported values: `simple`, ", inactive.SupportedTimestamps())
 		err = inactive.SetTimestampSource(ts)
 		if err != nil {
 			return nil, fmt.Errorf("%q: supported timestamps: %q, interface: %q", err, inactive.SupportedTimestamps(), ifi.Name)
@@ -345,7 +346,12 @@ func (l *Listener) read(handler PacketHandler) {
 				default:
 					data, ci, err := hndl.handler.ZeroCopyReadPacketData()
 					if err == nil {
+						if l.TimestampType == "go" {
+							ci.Timestamp = time.Now()
+						}
+
 						pckt, err := tcp.ParsePacket(data, linkType, linkSize, &ci, false)
+
 						if err == nil {
 							for _, p := range l.ports {
 								if pckt.DstPort == p {
diff --git a/simpletime/time.go b/simpletime/time.go
new file mode 100644
index 0000000..12d9deb
--- /dev/null
+++ b/simpletime/time.go
@@ -0,0 +1,17 @@
+package simpletime
+
+import (
+	"time"
+)
+
+var Now time.Time
+
+func init() {
+	go func() {
+		for {
+			// Accurate enough
+			Now = time.Now()
+			time.Sleep(100 * time.Millisecond)
+		}
+	}()
+}
diff --git a/tcp/tcp_message.go b/tcp/tcp_message.go
index 70d6e71..e89d5f8 100644
--- a/tcp/tcp_message.go
+++ b/tcp/tcp_message.go
@@ -9,6 +9,7 @@ import (
 	"time"
 	"unsafe"
 
+	"github.com/buger/goreplay/simpletime"
 	"github.com/buger/goreplay/size"
 )
 
@@ -39,7 +40,7 @@ func NewBufferPool(max int, ttl int) *bufPool {
 			for i := 0; i < 100; i++ {
 				select {
 				case c := <-pool.buffers:
-					if now.Sub(c.created) < time.Duration(ttl)*time.Second {
+					if simpletime.Now.Sub(c.created) < time.Duration(ttl)*time.Second {
 						select {
 						case pool.buffers <- c:
 						default:
@@ -81,7 +82,7 @@ func (p *bufPool) Get() *buf {
 
 		c = new(buf)
 		c.b = make([]byte, 1024)
-		c.created = now
+		c.created = simpletime.Now
 
 		// Use this technique to find if pool leaks, and objects get GCd
 		//
diff --git a/tcp/tcp_packet.go b/tcp/tcp_packet.go
index 4a20331..3358be4 100644
--- a/tcp/tcp_packet.go
+++ b/tcp/tcp_packet.go
@@ -9,6 +9,8 @@ import (
 	"runtime/debug"
 	"time"
 
+	"github.com/buger/goreplay/simpletime"
+
 	"github.com/google/gopacket"
 )
 
@@ -31,8 +33,6 @@ func copySlice(to []byte, from ...[]byte) ([]byte, int) {
 	return to, i
 }
 
-var now time.Time
-
 var stats *expvar.Map
 var bufPoolCount *expvar.Int
 var releasedCount *expvar.Int
@@ -45,14 +45,6 @@ func init() {
 	stats.Init()
 	stats.Set("buffer_pool_count", bufPoolCount)
 	stats.Set("buffer_released", releasedCount)
-
-	go func() {
-		for {
-			// Accurate enough
-			now = time.Now()
-			time.Sleep(500 * time.Millisecond)
-		}
-	}()
 }
 
 var packetPool = NewPacketPool(10000, 1)
@@ -79,7 +71,7 @@ func NewPacketPool(max int, ttl int) *pktPool {
 				select {
 				case c := <-pool.packets:
 					// GC If buffer is too big and lived for too long
-					if len(c.buf) < 8192 || now.Sub(c.created) < time.Duration(ttl)*time.Second {
+					if len(c.buf) < 8192 || simpletime.Now.Sub(c.created) < time.Duration(ttl)*time.Second {
 						select {
 						case pool.packets <- c:
 							// Jump to next item in for loop
@@ -120,7 +112,7 @@ func (p *pktPool) Get() *Packet {
 	default:
 		stats.Add("active_packet_count", 1)
 		c = new(Packet)
-		c.created = now
+		c.created = simpletime.Now
 
 		// Use this technique to find if pool leaks, and objects get GCd
 		//