streaming

commit 5446ee9238512d767735753f9f435b42ae4df0cc
parent eaad0eae5c24e2cdf206d68dc8ee75d395ce944c
Author: Joshua Callary <joshuacallary@miraitechnologies.com.au>
Date:   Sat, 20 Jul 2024 09:08:31 +1000

pcap: implement decoding

Diffstat:
A
pcap/parser.go
 | 
76
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
A
pcap/parser_test.go
 | 
34
++++++++++++++++++++++++++++++++++
A
pcap/testing/srt_capture_test.pcap
 | 
0

3 files changed, 110 insertions(+), 0 deletions(-)
diff --git a/pcap/parser.go b/pcap/parser.go
@@ -0,0 +1,76 @@
+package pcap
+
+import (
+	"encoding/binary"
+	"errors"
+	"io"
+)
+
+type GlobalHeader struct {
+	MagicNumber  uint32
+	VersionMajor uint16
+	VersionMinor uint16
+	ThisZone     int32
+	SigFigs      uint32
+	SnapLen      uint32
+	Network      uint32
+}
+
+type Header struct {
+	TsSec   uint32
+	TsUsec  uint32
+	InclLen uint32
+	OrigLen uint32
+}
+
+type Packet struct {
+	Header Header
+	Data   []byte
+}
+
+type File struct {
+	Header  GlobalHeader
+	Packets []Packet
+}
+
+func decode(reader io.Reader) (*File, error) {
+	var header GlobalHeader
+	err := binary.Read(reader, binary.LittleEndian, &header)
+
+	if err != nil {
+		return nil, err
+	}
+
+	if header.MagicNumber != 0xa1b2c3d4 && header.MagicNumber != 0xd4c3b2a1 {
+		return nil, errors.New("invalid magic number in pcap file")
+	}
+
+	var packets []Packet
+
+	for {
+		var header Header
+		err := binary.Read(reader, binary.LittleEndian, &header)
+		if err == io.EOF {
+			break
+		}
+		if err != nil {
+			return nil, err
+		}
+
+		data := make([]byte, header.InclLen)
+		_, err = io.ReadFull(reader, data)
+		if err != nil {
+			return nil, err
+		}
+
+		packets = append(packets, Packet{
+			Header: header,
+			Data:   data,
+		})
+	}
+
+	return &File{
+		Header:  header,
+		Packets: packets,
+	}, nil
+}
diff --git a/pcap/parser_test.go b/pcap/parser_test.go
@@ -0,0 +1,34 @@
+package pcap
+
+import (
+	"fmt"
+	"os"
+	"testing"
+)
+
+func TestReadFile(t *testing.T) {
+	filePath := "testing/srt_capture_test.pcap"
+
+	file, err := os.Open(filePath)
+	if err != nil {
+		t.Fatal("Failed to open file")
+	}
+	defer file.Close()
+
+	pcapFile, err := decode(file)
+	if err != nil {
+		t.Fatalf("Failed to read PCAP file: %v", err)
+	}
+
+	if len(pcapFile.Packets) == 0 {
+		t.Fatal("Should be at least one packet but there is 0")
+	}
+
+	fmt.Printf("PCAP Header: %+v\n", pcapFile.Header)
+
+	for i, packet := range pcapFile.Packets {
+		fmt.Printf("Packet %d: %+v\n", i, packet.Header)
+
+		fmt.Printf("Data %d: %x\n", i, packet.Data)
+	}
+}
diff --git a/pcap/testing/srt_capture_test.pcap b/pcap/testing/srt_capture_test.pcap
Binary files differ.