Checksumming and USB port searching works

firmware/firmware.go

@@ -0,0 +1,77 @@
+package firmware
+
+import (
+	"bytes"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"hash/crc32"
+	"io"
+	"io/ioutil"
+	"os"
+	"path"
+)
+
+// FwExists  check if file exists
+func FwExists(path string) bool {
+	_, err := os.Stat(path)
+	return !errors.Is(err, os.ErrNotExist)
+}
+
+func ChkHeader(fwfile string) bool {
+	fmt.Println("checking ", fwfile)
+	// SCS has two different file layouts, one for the "Dragons", the other for any older modem
+	var offset uint32
+	if path.Ext(fwfile) == ".dr7" {
+		offset = 0
+	} else {
+		offset = 4
+	}
+	r, err := os.Open(fwfile)
+	if err != nil {
+		return false
+	}
+	defer r.Close()
+
+	var header [2]byte
+	_, err = io.ReadFull(r, header[:])
+	if err != nil {
+		return false
+	}
+
+	if offset == 0 {
+		if header != [2]byte{0x50, 0x34} {
+			fmt.Println("ERROR: wrong firmware header")
+			//return false
+		}
+	} else {
+		if header != [2]byte{0x60, 0xea} {
+			fmt.Println("ERROR: wrong firmware header")
+			//return false
+		}
+	}
+
+	r.Close()
+	firmware, err := ioutil.ReadFile(fwfile)
+	if err != nil {
+		fmt.Println("ERROR: ReadFile operation failed")
+	}
+
+	var size uint32
+	if offset == 0 {
+		size = binary.LittleEndian.Uint32(firmware[4:8]) // Dragons
+	} else {
+		size = uint32(binary.LittleEndian.Uint16(firmware[2:4])) // PTC-3 and Co
+	}
+	a := make([]byte, 4)
+	//binary.LittleEndian.PutUint32(a, crc32.ChecksumIEEE(firmware[4:size+4])) // PTC-3
+	binary.LittleEndian.PutUint32(a, crc32.ChecksumIEEE(firmware[offset:offset+size]))
+	//if bytes.Equal(a, firmware[4+size:8+size]) { // PTC-3
+	if bytes.Equal(a, firmware[offset+size:offset+size+4]) {
+		fmt.Println("CRC checksum ok!")
+	} else {
+		fmt.Println("CRC checksum NOT ok!")
+		return false
+	}
+	return true
+}