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use structured logging to enable easier log parsing #3

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15 changes: 9 additions & 6 deletions cmd/main.go
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Original file line number Diff line number Diff line change
@@ -1,8 +1,8 @@
package main

import (
"fmt"
"log"
"log/slog"
"os"
"time"

"github.com/google/gopacket"
Expand All @@ -14,6 +14,7 @@ import (
)

func main() {
logger := slog.New(slog.NewTextHandler(os.Stdout, nil))

// Load FingerPrints
ja4Map, ja4sMap, err := parser.LoadFingerPrints("fingerprints.json")
Expand All @@ -25,14 +26,16 @@ func main() {
handle, err := pcap.OpenLive("enp0s3", 65535, true, pcap.BlockForever)
//handle, err := pcap.OpenLive("eth0", 65535, true, pcap.BlockForever)
if err != nil {
log.Fatal(err)
logger.Error("fatal error occurred", "err", err.Error())
os.Exit(1)
}
defer handle.Close()

//err = handle.SetBPFFilter("tcp port 443")
err = handle.SetBPFFilter("tcp")
if err != nil {
log.Fatal(err)
logger.Error("fatal error occurred", "err", err.Error())
os.Exit(1)
}

// Till here is normal flow
Expand All @@ -58,7 +61,7 @@ func main() {
// End of pcap files

packetSource := gopacket.NewPacketSource(handle, handle.LinkType())
fmt.Println("DLT: ", handle.LinkType())
logger.Debug("process started", "DLT", handle.LinkType())
for {
select {
case packet := <-packetSource.Packets():
Expand All @@ -82,7 +85,7 @@ func main() {
// Avoid resource leak by cleaning up
cutoff := time.Now().Add(-2 * time.Minute)
flushedConn, closedConn := assembler.FlushWithOptions(tcpassembly.FlushOptions{CloseAll: false, T: cutoff})
fmt.Printf("FlushWithOptions - flushedConn: %v closedConn: %v\n", flushedConn, closedConn)
logger.Debug("flush", "flushed", flushedConn, "closed", closedConn)
}
}
}
39 changes: 21 additions & 18 deletions internal/parser/fingerprint_parser.go
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@ package parser
import (
"encoding/json"
"fmt"
"log/slog"
"os"

"github.com/voukatas/go-ja4/internal/model"
Expand Down Expand Up @@ -73,24 +74,26 @@ func LoadFingerPrints(fileName string) (map[string]*model.FingerprintRecord, map
}

func PrintRecord(record *model.FingerprintRecord) {
fmt.Printf(" Application: %s\n", deref(record.Application))
fmt.Printf(" Library: %s\n", deref(record.Library))
fmt.Printf(" Device: %s\n", deref(record.Device))
fmt.Printf(" OS: %s\n", deref(record.OS))
fmt.Printf(" User Agent String: %s\n", deref(record.UserAgentString))
fmt.Printf(" Certificate Authority: %s\n", deref(record.CertificateAuthority))
fmt.Printf(" Observation Count: %d\n", record.ObservationCount)
fmt.Printf(" Verified: %t\n", record.Verified)
fmt.Printf(" Notes: %s\n", deref(record.Notes))
fmt.Printf(" JA4 Fingerprint: %s\n", deref(record.Ja4Fingerprint))
fmt.Printf(" JA4 Fingerprint String: %s\n", deref(record.Ja4FingerprintString))
fmt.Printf(" JA4s Fingerprint: %s\n", deref(record.Ja4sFingerprint))
fmt.Printf(" JA4h Fingerprint: %s\n", deref(record.Ja4hFingerprint))
fmt.Printf(" JA4x Fingerprint: %s\n", deref(record.Ja4xFingerprint))
fmt.Printf(" JA4t Fingerprint: %s\n", deref(record.Ja4tFingerprint))
fmt.Printf(" JA4ts Fingerprint: %s\n", deref(record.Ja4tsFingerprint))
fmt.Printf(" JA4tscan Fingerprint: %s\n", deref(record.Ja4tscanFingerprint))
fmt.Println()
logger := slog.New(slog.NewTextHandler(os.Stdout, nil))
logger.Info("matched known fingerprint",
slog.String("application", deref(record.Application)),
slog.String("library", deref(record.Library)),
slog.String("device", deref(record.Device)),
slog.String("os", deref(record.OS)),
slog.String("user_agent_string", deref(record.UserAgentString)),
slog.String("certificate_authority", deref(record.CertificateAuthority)),
slog.Int("observation_count", record.ObservationCount),
slog.Bool("verified", record.Verified),
slog.String("notes", deref(record.Notes)),
slog.String("JA4_fingerprint", deref(record.Ja4Fingerprint)),
slog.String("JA4_fingerprint_string", deref(record.Ja4FingerprintString)),
slog.String("JA4s_fingerprint", deref(record.Ja4sFingerprint)),
slog.String("JA4h_fingerprint", deref(record.Ja4hFingerprint)),
slog.String("JA4x_fingerprint", deref(record.Ja4xFingerprint)),
slog.String("JA4t_fingerprint", deref(record.Ja4tFingerprint)),
slog.String("JA4ts_fingerprint", deref(record.Ja4tsFingerprint)),
slog.String("JA4tscan_fingerprint", deref(record.Ja4tscanFingerprint)),
)
}

func deref(str *string) string {
Expand Down
15 changes: 8 additions & 7 deletions internal/tcp/stream_processor.go
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Original file line number Diff line number Diff line change
Expand Up @@ -3,9 +3,9 @@ package tcp
import (
"bytes"
"encoding/binary"
"fmt"
"io"
"log"
"log/slog"
"os"

"github.com/google/gopacket"
"github.com/google/gopacket/tcpassembly/tcpreader"
Expand All @@ -17,6 +17,7 @@ import (
const maxBufferSize = 16 * 1024 // 16 KB

func processStream(r *tcpreader.ReaderStream, net gopacket.Flow, ja4Map, ja4sMap map[string]*model.FingerprintRecord) {
logger := slog.New(slog.NewTextHandler(os.Stdout, nil))
// fmt.Printf("Processing stream from %v to %v\n", net.Src(), net.Dst())
// defer fmt.Printf("Finished processing stream from %v to %v\n", net.Src(), net.Dst())
var buffer bytes.Buffer
Expand All @@ -29,7 +30,7 @@ func processStream(r *tcpreader.ReaderStream, net gopacket.Flow, ja4Map, ja4sMap
break
}

log.Println("Error reading from stream:", err)
logger.Error("error reading from stream", "err", err.Error())
return
}

Expand Down Expand Up @@ -70,9 +71,9 @@ func processStream(r *tcpreader.ReaderStream, net gopacket.Flow, ja4Map, ja4sMap
protocol := 't'
ja4Fingerprint, err := ja4.ParseClientHelloForJA4(data[:totalLength], byte(protocol))
if err != nil {
fmt.Println("Error parsing TLS Client Hello:", err)
logger.Error("error parsing TLS Client Hello", "err", err.Error())
} else {
fmt.Printf("JA4 Fingerprint: %s network: %v\n", ja4Fingerprint, net)
logger.Info("found JA4 fingerprint", "ja4", ja4Fingerprint, "src", net.Src(), "dest", net.Dst())
if val := ja4Map[ja4Fingerprint]; val != nil {
parser.PrintRecord(val)
}
Expand All @@ -88,10 +89,10 @@ func processStream(r *tcpreader.ReaderStream, net gopacket.Flow, ja4Map, ja4sMap
protocol := 't' // 't' for TCP
ja4sFingerprint, err := ja4.ParseServerHelloForJA4S(data[:totalLength], byte(protocol))
if err != nil {
fmt.Println("Error parsing TLS Server Hello:", err)
logger.Error("error parsing TLS Server Hello:", "err", err.Error())
} else {
//fmt.Printf("JA4S Fingerprint: %s\n", ja4sFingerprint)
fmt.Printf("JA4S Fingerprint: %s network: %v\n", ja4sFingerprint, net)
logger.Info("found JA4S fingerprint", "ja4s", ja4sFingerprint, "src", net.Src(), "dst", net.Dst())
if val := ja4sMap[ja4sFingerprint]; val != nil {
parser.PrintRecord(val)
}
Expand Down