From 3a7a53fdb919aeedef7441cb7a1618e1b88596c4 Mon Sep 17 00:00:00 2001
From: Marten Seemann <martenseemann@gmail.com>
Date: Fri, 2 Feb 2024 17:17:56 +0700
Subject: [PATCH] qlog: log packet drops outside of a QUIC connection

---
 qlog/tracer.go      | 11 ++++++++++-
 qlog/tracer_test.go | 18 ++++++++++++++++++
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/qlog/tracer.go b/qlog/tracer.go
index 4d567875..85398f9f 100644
--- a/qlog/tracer.go
+++ b/qlog/tracer.go
@@ -2,8 +2,10 @@ package qlog
 
 import (
 	"io"
+	"net"
 	"time"
 
+	"github.com/quic-go/quic-go/internal/protocol"
 	"github.com/quic-go/quic-go/logging"
 )
 
@@ -17,7 +19,14 @@ func NewTracer(w io.WriteCloser) *logging.Tracer {
 	return &logging.Tracer{
 		SentPacket:                   nil,
 		SentVersionNegotiationPacket: nil,
-		DroppedPacket:                nil,
+		DroppedPacket: func(addr net.Addr, p logging.PacketType, count logging.ByteCount, reason logging.PacketDropReason) {
+			wr.RecordEvent(time.Now(), eventPacketDropped{
+				PacketType:   p,
+				PacketNumber: protocol.InvalidPacketNumber,
+				PacketSize:   count,
+				Trigger:      packetDropReason(reason),
+			})
+		},
 		Debug: func(name, msg string) {
 			wr.RecordEvent(time.Now(), &eventGeneric{
 				name: name,
diff --git a/qlog/tracer_test.go b/qlog/tracer_test.go
index 46f41522..990e4165 100644
--- a/qlog/tracer_test.go
+++ b/qlog/tracer_test.go
@@ -3,6 +3,7 @@ package qlog
 import (
 	"bytes"
 	"encoding/json"
+	"net"
 	"time"
 
 	"github.com/quic-go/quic-go/logging"
@@ -45,6 +46,23 @@ var _ = Describe("Tracing", func() {
 	})
 
 	Context("Events", func() {
+		It("records dropped packets", func() {
+			addr := net.UDPAddr{IP: net.IPv4(1, 2, 3, 4), Port: 1234}
+			tracer.DroppedPacket(&addr, logging.PacketTypeInitial, 1337, logging.PacketDropPayloadDecryptError)
+			tracer.Close()
+			entry := exportAndParseSingle(buf)
+			Expect(entry.Time).To(BeTemporally("~", time.Now(), scaleDuration(10*time.Millisecond)))
+			Expect(entry.Name).To(Equal("transport:packet_dropped"))
+			ev := entry.Event
+			Expect(ev).To(HaveKey("raw"))
+			Expect(ev["raw"].(map[string]interface{})).To(HaveKeyWithValue("length", float64(1337)))
+			Expect(ev).To(HaveKey("header"))
+			hdr := ev["header"].(map[string]interface{})
+			Expect(hdr).To(HaveLen(1))
+			Expect(hdr).To(HaveKeyWithValue("packet_type", "initial"))
+			Expect(ev).To(HaveKeyWithValue("trigger", "payload_decrypt_error"))
+		})
+
 		It("records a generic event", func() {
 			tracer.Debug("foo", "bar")
 			tracer.Close()