qlog the quic-go version

This only works when quic-go is used as a library.

qlog/qlog.go

@@ -6,6 +6,7 @@ import (
 	"io"
 	"log"
 	"net"
+	"runtime/debug"
 	"sync"
 	"time"
 
@@ -17,6 +18,24 @@ import (
 	"github.com/francoispqt/gojay"
 )
 
+var quicGoVersion = "(devel)"
+
+func init() {
+	info, ok := debug.ReadBuildInfo()
+	if !ok { // no build info available. This happens when quic-go is not used as a library.
+		return
+	}
+	for _, d := range info.Deps {
+		if d.Path == "github.com/lucas-clemente/quic-go" {
+			quicGoVersion = d.Version
+			if d.Replace != nil {
+				quicGoVersion += " (replaced)"
+			}
+			break
+		}
+	}
+}
+
 const eventChanSize = 50
 
 type tracer struct {

qlog/trace.go

@@ -17,6 +17,7 @@ func (l topLevel) MarshalJSONObject(enc *gojay.Encoder) {
 	enc.StringKey("qlog_format", "NDJSON")
 	enc.StringKey("qlog_version", "draft-02")
 	enc.StringKeyOmitEmpty("title", "quic-go qlog")
+	enc.StringKey("code_version", quicGoVersion)
 	enc.ObjectKey("trace", l.trace)
 }