diff options
| -rw-r--r-- | eizo-pcap-decode.go | 212 |
1 files changed, 212 insertions, 0 deletions
diff --git a/eizo-pcap-decode.go b/eizo-pcap-decode.go new file mode 100644 index 0000000..838919e --- /dev/null +++ b/eizo-pcap-decode.go @@ -0,0 +1,212 @@ +// Usage: tshark { -r FILE | -i INTERFACE } -l -T ek \ +// | go run eizo-pcap-decode.go [ | less -R] +// +// This cannot be done through -T json, because tshark doesn't immediately +// flush the current object's trailing newline, but rather waits to decide +// if it should follow it with a comma. Even with -l, it will flush it late. +// It would be good if we could convince it not to wrap packets in a big array. +package main + +import ( + "encoding/binary" + "encoding/hex" + "encoding/json" + "errors" + "flag" + "fmt" + "io" + "os" + "strings" +) + +type Packet struct { + Layers struct { + USB struct { + Source string `json:"usb_usb_src"` + Destination string `json:"usb_usb_dst"` + Direction string `json:"usb_usb_endpoint_address_direction"` + MacEndpointType string `json:"usb_usb_darwin_endpoint_type"` + TransferType string `json:"usb_usb_transfer_type"` + } `json:"usb"` + CapData string `json:"usb_usb_capdata"` + ControlResponse string `json:"usb_usb_control_Response"` + DataFragment string `json:"usb_usb_data_fragment"` + } `json:"layers"` +} + +func (p *Packet) addr() string { + if p.Layers.USB.Source == "host" { + return p.Layers.USB.Destination + } else { + return p.Layers.USB.Source + } +} + +func (p *Packet) isInterrupt() bool { + return p.Layers.USB.MacEndpointType == "3" || + p.Layers.USB.TransferType == "0x01" +} + +func (p *Packet) isControl() bool { + return p.Layers.USB.MacEndpointType == "0" || + p.Layers.USB.TransferType == "0x02" +} + +func (p *Packet) isIncoming() bool { + return p.Layers.USB.Direction == "1" +} + +func hexDecode(encoded string) []byte { + decoded, err := hex.DecodeString(strings.ReplaceAll(encoded, ":", "")) + if err != nil { + panic(err) + } + return decoded +} + +// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - + +var ( + raw *bool + le = binary.LittleEndian + + fmtIn, fmtOut, fmtReset string +) + +func decodeSubreport(data []byte) string { + if len(data) < 6 { + return fmt.Sprintf("%x", data) + } + usage := uint32(le.Uint16(data[:2]))<<16 | uint32(le.Uint16(data[2:4])) + filtered := make([]byte, len(data)-6) + for i, b := range data[6:] { + if b < 32 || b > 126 { + filtered[i] = '.' + } else { + filtered[i] = b + } + } + return fmt.Sprintf("<> %08x %04x %x %s", usage, le.Uint16(data[4:6]), + data[6:], string(filtered)) +} + +func decodeResult(data []byte) string { + if len(data) < 7 { + return fmt.Sprintf("%x", data) + } + usage := uint32(le.Uint16(data[:2]))<<16 | uint32(le.Uint16(data[2:4])) + return fmt.Sprintf(">< %08x %04x %02x", usage, le.Uint16(data[4:6]), + data[6]) +} + +func decodeMP(data []byte) string { + var out string + for i := 0; i+1 < len(data); { + sz := int(data[i+1]) + if data[i] == 0xff || i+sz > len(data) { + break + } + if out != "" { + out += " " + } + out += fmt.Sprintf("[%02x] %x", data[i], data[i+2:i+2+sz]) + i += 2 + sz + } + return out +} + +func isSetSubreport(id byte) bool { + switch id { + case 2, 4, 11, 13: + return true + } + return false +} + +func isGetSubreport(id byte) bool { + switch id { + case 3, 5, 12, 14: + return true + } + return false +} + +func isSubreport(id byte) bool { + return isSetSubreport(id) || isGetSubreport(id) +} + +func processInterrupt(p *Packet) { + data := hexDecode(p.Layers.CapData) + if len(data) < 1 { + return + } + if *raw { + fmt.Printf("%s INT %02x %x\n", p.addr(), data[0], data[1:]) + } else if isSubreport(data[0]) { + fmt.Printf("%s INT %s\n", p.addr(), decodeSubreport(data[1:])) + } +} + +func processControl(p *Packet) { + // macOS (Darwin) and Linux report Set_Feature differently. + data := hexDecode(p.Layers.ControlResponse) + if len(data) == 0 { + data = hexDecode(p.Layers.DataFragment) + } + if len(data) < 1 { + return + } + if p.isIncoming() { + if *raw { + fmt.Printf("%s IN %02x %x\n", p.addr(), data[0], data[1:]) + } else if data[0] == 1 { + fmt.Printf("%s IN SR %x\n", p.addr(), data[5:]) + } else if isGetSubreport(data[0]) { + fmt.Printf("%s IN %s%s%s\n", p.addr(), + fmtIn, decodeSubreport(data[1:]), fmtReset) + } else if data[0] == 6 { + fmt.Printf("%s IN PC %04x\n", p.addr(), le.Uint16(data[1:])) + } else if data[0] == 7 { + fmt.Printf("%s IN %s\n", p.addr(), decodeResult(data[1:])) + } else if data[0] == 8 { + fmt.Printf("%s IN ID %s %s\n", p.addr(), data[1:9], data[9:]) + } else if data[0] == 9 { + fmt.Printf("%s IN MP %s\n", p.addr(), decodeMP(data[1:])) + } else { + fmt.Printf("%s IN %02x %x\n", p.addr(), data[0], data[1:]) + } + } else { + if *raw { + fmt.Printf("%s OUT %02x %x\n", p.addr(), data[0], data[1:]) + } else if isSetSubreport(data[0]) { + fmt.Printf("%s OUT %s%s%s\n", p.addr(), + fmtOut, decodeSubreport(data[1:]), fmtReset) + } else if data[0] != 1 && !isGetSubreport(data[0]) { + fmt.Printf("%s OUT %02x %x\n", p.addr(), data[0], data[1:]) + } + } +} + +func main() { + raw = flag.Bool("raw", false, "Do not decode EIZO packets") + flag.Parse() + + if _, ok := os.LookupEnv("NO_COLOR"); !ok { + fmtIn, fmtOut, fmtReset = "\x1b[34m", "\x1b[31m", "\x1b[m" + } + + decoder := json.NewDecoder(os.Stdin) + for { + var p Packet + if err := decoder.Decode(&p); err != nil { + if errors.Is(err, io.EOF) { + break + } + fmt.Fprintf(os.Stderr, "%v\n", err) + } else if p.isInterrupt() { + processInterrupt(&p) + } else if p.isControl() { + processControl(&p) + } + } +} |