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Implement first client command

Browse source 
The client can now talk to the old Perl signer implementation. Running
socat has been documented in README.md. Commonly used I/O code has been
moved to the shared/io.go file.
This commit is contained in:
Jan Dittberner 2020-04-17 19:38:54 +02:00
parent 5aa557c9aa
commit 65855152ce
6 changed files with 287 additions and 84 deletions
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26
README.md Normal file
View file

@ -0,0 +1,26 @@
# CAcert signer in Go
This is a reimplementation of the CAcert signer code from the
[CommModule directory](https://git.cacert.org/gitweb/?p=cacert-devel.git;a=tree;f=CommModule) of the CAcert software
in [Go](https://golang.org/). The goal of this effort is to provide a more maintainable version of the software.
## Running the signer and client locally
The signer is usually attached to a USB serial port. You can run the signer and client locally using the
[socat](https://manpages.debian.org/buster/socat/socat.1.en.html) utility.
```shell script
socat -d -d PTY,link=$(pwd)/ttyS0 PTY,link=$(pwd)/ttyS1
```
You may then run the server
```shell script
go run signer/main.go -a $(pwd)/dev/ttyS0
```
and the client:
```shell script
go run client/main.go -a $(pwd)/dev/ttyS1
```

262
client/main.go
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@ -1,71 +1,132 @@
package main
import (
"encoding/binary"
"errors"
"flag"
"fmt"
"git.cacert.org/cacert-gosigner/datastructures"
"git.cacert.org/cacert-gosigner/shared"
"log"
"io/ioutil"
"time"
"github.com/goburrow/serial"
log "github.com/sirupsen/logrus"
"gopkg.in/yaml.v2"
)
var (
address string
baudrate int
databits int
stopbits int
parity string
message string
)
type SerialConfig struct {
Address string `yaml:"address"`
BaudRate int `yaml:"baudrate"`
DataBits int `yaml:"databits"`
StopBits int `yaml:"stopbits"`
Parity string `yaml:"parity"`
}
type ClientConfig struct {
Serial SerialConfig `yaml:"serial_config"`
Paranoid bool `yaml:"paranoid"`
Debug bool `yaml:"debug"`
GNUPGBinary string `yaml:"gnupg_bin"`
OpenSSLBinary string `yaml:"openssl_bin"`
MySQLDSN string `yaml:"mysql_dsn"`
}
var defaultConfig = ClientConfig{
Serial: SerialConfig{
Address: "/dev/ttyUSB0",
BaudRate: 115200,
DataBits: 8,
StopBits: 1,
Parity: "N",
},
Paranoid: false,
Debug: false,
OpenSSLBinary: "/usr/bin/openssl",
GNUPGBinary: "/usr/bin/gpg",
MySQLDSN: "<username>:<password>@/database?parseTime=true",
}
const HandshakeByte = 0x02
const AckByte = 0x10
const NackByte = 0x11
func readConfig(configFile string) (config *ClientConfig, err error) {
source, err := ioutil.ReadFile(configFile)
if err != nil {
log.Errorf("opening configuration file failed: %v", err)
if exampleConfig, err := generateExampleConfig(configFile); err != nil {
return nil, err
} else {
log.Info("starting with default config")
return exampleConfig, nil
}
}
if err := yaml.Unmarshal(source, &config); err != nil {
return nil, fmt.Errorf("loading configuration file failed: %v", err)
}
return config, nil
}
func generateExampleConfig(configFile string) (config *ClientConfig, err error) {
config = &defaultConfig
configBytes, err := yaml.Marshal(config)
if err != nil {
log.Errorf("could not generate configuration data")
return
}
log.Infof("example data for %s:\n\n---\n%s\n", configFile, configBytes)
return
}
func main() {
flag.StringVar(&address, "a", "/dev/ttyUSB0", "address")
flag.IntVar(&baudrate, "b", 115200, "baud rate")
flag.IntVar(&databits, "d", 8, "data bits")
flag.IntVar(&stopbits, "s", 1, "stop bits")
flag.StringVar(&parity, "p", "N", "parity (N/E/O)")
flag.StringVar(&message, "m", "serial", "message")
var configFile string
flag.StringVar(&configFile, "c", "client.yaml", "client configuration file in YAML format")
flag.Parse()
config := serial.Config{
Address: address,
BaudRate: baudrate,
DataBits: databits,
StopBits: stopbits,
Parity: parity,
var clientConfig *ClientConfig
var serialConfig *serial.Config
var err error
if clientConfig, err = readConfig(configFile); err != nil {
log.Panic(err)
}
serialConfig = &serial.Config{
Address: clientConfig.Serial.Address,
BaudRate: clientConfig.Serial.BaudRate,
DataBits: clientConfig.Serial.DataBits,
StopBits: clientConfig.Serial.StopBits,
Parity: clientConfig.Serial.Parity,
Timeout: 30 * time.Second,
}
log.Printf("connecting %+v", config)
port, err := serial.Open(&config)
if clientConfig.Debug {
log.SetLevel(log.DebugLevel)
}
log.Debugf("connecting %+v", serialConfig)
port, err := serial.Open(serialConfig)
if err != nil {
log.Fatal(err)
}
log.Println("connected")
log.Debug("connected")
defer func() {
err := port.Close()
if err != nil {
log.Fatal(err)
}
log.Println("closed")
log.Debug("closed")
}()
if _, err = port.Write([]byte{0x02}); err != nil {
log.Fatal(err)
}
resp := make([]byte, 1)
if _, err = port.Read(resp); err != nil {
log.Fatal(err)
}
request := datastructures.NewNulRequest()
timeout := time.After(2700 * time.Millisecond)
errorChannel := make(chan error, 1)
responseChannel := make(chan *datastructures.SignerResponse, 1)
go func() {
if response, err := SendRequest(&port, request); err != nil {
if response, err := SendRequest(port, request); err != nil {
errorChannel <- err
} else {
responseChannel <- response
@ -82,25 +143,128 @@ func main() {
log.Fatal(err)
}
}
requestBytes := request.Serialize()
if _, err = port.Write(requestBytes); err != nil {
log.Fatal(err)
}
if _, err = port.Write([]byte{datastructures.CalculateXorCheckSum([][]byte{requestBytes})}); err != nil {
log.Fatal(err)
}
if _, err = port.Write([]byte(shared.MagicTrailer)); err != nil {
log.Fatal(err)
}
}
func Process(response *datastructures.SignerResponse) error {
log.Debugf("process %v", response)
return nil
}
func SendRequest(port *serial.Port, request *datastructures.SignerRequest) (*datastructures.SignerResponse, error) {
func sendHandShake(port serial.Port) error {
log.Debug("Shaking hands ...")
if length, err := port.Write([]byte{HandshakeByte}); err != nil {
return fmt.Errorf("could not write handshake byte: %v", err)
} else {
log.Debugf("wrote %d handshake bytes", length)
}
handShakeResponse := make([]byte, 1)
if length, err := port.Read(handShakeResponse); err != nil {
return fmt.Errorf("failed to read handshake response: %v", err)
} else {
log.Debugf("read %d bytes", length)
}
if handShakeResponse[0] != AckByte {
return fmt.Errorf("invalid handshake response expected 0x10 received %x", handShakeResponse[0])
}
log.Debug("Handshake successful")
return nil
}
func receiveResponse(port *serial.Port, responseChan *chan []byte, errorChan *chan error) {
header, err := shared.ReceiveBytes(port, 1, 20)
if err != nil {
*errorChan <- err
return
}
if header[0] != HandshakeByte {
*errorChan <- fmt.Errorf("unexpected byte 0x%x expected 0x%x", header, HandshakeByte)
}
if _, err := (*port).Write([]byte{AckByte}); err != nil {
*errorChan <- errors.New("could not write ACK")
return
}
lengthBytes, err := shared.ReceiveBytes(port, 3, 2)
if err != nil {
*errorChan <- err
return
}
blockLength := binary.BigEndian.Uint32([]byte{0x0, lengthBytes[0], lengthBytes[1], lengthBytes[2]})
blockData, err := shared.ReceiveBytes(port, int(blockLength), 5)
if err != nil {
*errorChan <- err
return
}
checkSum, err := shared.ReceiveBytes(port, 1, 2)
if err != nil {
*errorChan <- err
return
}
log.Debugf("block checksum is %d", checkSum)
trailer, err := shared.ReceiveBytes(port, len(shared.MagicTrailer), 2)
if err != nil {
*errorChan <- err
return
}
if string(trailer) != shared.MagicTrailer {
*errorChan <- errors.New("expected trailer bytes not found")
return
}
if _, err := (*port).Write([]byte{AckByte}); err != nil {
*errorChan <- fmt.Errorf("could not write ACK byte: %v", err)
}
*responseChan <- blockData
return
}
func SendRequest(port serial.Port, request *datastructures.SignerRequest) (response *datastructures.SignerResponse, err error) {
log.Debugf("send request %v to serial port %v", request, port)
if err = sendHandShake(port); err != nil {
return nil, err
}
requestBytes := request.Serialize()
if length, err := port.Write(requestBytes); err != nil {
log.Fatal(err)
} else {
log.Debugf("wrote %d request bytes", length)
}
if length, err := port.Write([]byte{datastructures.CalculateXorCheckSum([][]byte{requestBytes})}); err != nil {
log.Fatal(err)
} else {
log.Debugf("wrote %d checksum bytes", length)
}
if length, err := port.Write([]byte(shared.MagicTrailer)); err != nil {
log.Fatal(err)
} else {
log.Debugf("wrote %d trailer bytes", length)
}
header, err := shared.ReceiveBytes(&port, 1, 20)
if err != nil {
return nil, err
}
if header[0] != AckByte {
return nil, fmt.Errorf("unexpected byte 0x%x expected 0x%x", header, AckByte)
}
responseChan := make(chan []byte, 1)
errChan := make(chan error, 1)
go receiveResponse(&port, &responseChan, &errChan)
select {
case responseData := <-responseChan:
log.Debugf("response data: %v", responseData)
case err := <-errChan:
log.Errorf("%v", err)
}
return nil, nil
}

8
datastructures/signerrequest.go
View file

@ -22,6 +22,8 @@ type SignerRequest struct {
Content3 string
}
const protocolVersion = 1
func SignerRequestFromData(lengthBytes []byte, blockData []byte, checkSum byte) (*SignerRequest, error) {
headerLength := decode24BitLength(blockData[0:3])
headerBytes := blockData[3 : 3+headerLength]
@ -76,5 +78,9 @@ func (r SignerRequest) Serialize() []byte {
}
func NewNulRequest() *SignerRequest {
return &SignerRequest{Version: 1, Action: ActionNul, Content1: time.Now().UTC().Format("010203042006.05")}
return &SignerRequest{
Version: protocolVersion,
Action: ActionNul,
Content1: time.Now().UTC().Format("010203042006.05"),
}
}

31
shared/io.go Normal file
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@ -0,0 +1,31 @@
package shared
import (
"errors"
"github.com/goburrow/serial"
"io"
"time"
)
// receive the requested number of bytes from serial port and stop after the given timeout in seconds
func ReceiveBytes(port *serial.Port, count int, timeout time.Duration) ([]byte, error) {
timeoutCh := time.After(timeout * time.Second)
readCh := make(chan []byte, 1)
errCh := make(chan error, 1)
go func() {
data := make([]byte, count)
if _, err := io.ReadAtLeast(*port, data, count); err != nil {
errCh <- err
} else {
readCh <- data
}
}()
select {
case <-timeoutCh:
return nil, errors.New("timeout")
case err := <-errCh:
return nil, err
case data := <-readCh:
return data, nil
}
}

1
shared/shared.go
View file

@ -1,4 +1,3 @@
package shared
const MagicTrailer = "rie4Ech7"

41
signer/main.go
View file

@ -7,7 +7,6 @@ import (
"fmt"
"git.cacert.org/cacert-gosigner/datastructures"
"git.cacert.org/cacert-gosigner/shared"
"io"
"log"
"time"
@ -70,7 +69,7 @@ readLoop:
if err != nil {
log.Printf("ERROR %v\n", err)
} else {
SendResponse(&port, response)
_ = SendResponse(&port, response)
}
case <-timeout:
log.Println("timeout in main loop")
@ -90,7 +89,7 @@ func SendResponse(port *serial.Port, response *datastructures.SignerResponse) er
return err
}
if ack, err := receiveBytes(port, 1, 5); err != nil {
if ack, err := shared.ReceiveBytes(port, 1, 5); err != nil {
return err
} else if ack[0] != 0x10 {
return errors.New(fmt.Sprintf("invalid ack byte 0x%02x", ack[0]))
@ -112,7 +111,7 @@ func SendResponse(port *serial.Port, response *datastructures.SignerResponse) er
return err
}
if ack, err := receiveBytes(port, 1, 5); err != nil {
if ack, err := shared.ReceiveBytes(port, 1, 5); err != nil {
return err
} else if ack[0] == 0x10 {
tryAgain = false
@ -146,13 +145,13 @@ func handleNulAction(command datastructures.SignerRequest) (*datastructures.Sign
// Receive a request and generate a request data structure
func Receive(port *serial.Port, commandChan *chan datastructures.SignerRequest, errorChan *chan error) {
header, err := receiveBytes(port, 1, 20)
header, err := shared.ReceiveBytes(port, 1, 20)
if err != nil {
*errorChan <- err
return
}
if header[0] != 0x02 {
*errorChan <- errors.New(fmt.Sprintf("unexpected byte 0x%x expected 0x02", header))
*errorChan <- fmt.Errorf("unexpected byte 0x%x expected 0x02", header)
}
if _, err := (*port).Write([]byte{0x10}); err != nil {
@ -160,19 +159,19 @@ func Receive(port *serial.Port, commandChan *chan datastructures.SignerRequest,
return
}
lengthBytes, err := receiveBytes(port, 3, 2)
lengthBytes, err := shared.ReceiveBytes(port, 3, 2)
if err != nil {
*errorChan <- err
return
}
blockLength := binary.BigEndian.Uint32([]byte{0x0, lengthBytes[0], lengthBytes[1], lengthBytes[2]})
blockData, err := receiveBytes(port, int(blockLength), 5)
blockData, err := shared.ReceiveBytes(port, int(blockLength), 5)
if err != nil {
*errorChan <- err
return
}
checkSum, err := receiveBytes(port, 1, 2)
checkSum, err := shared.ReceiveBytes(port, 1, 2)
if err != nil {
*errorChan <- err
return
@ -183,7 +182,7 @@ func Receive(port *serial.Port, commandChan *chan datastructures.SignerRequest,
*errorChan <- err
}
trailer, err := receiveBytes(port, len(shared.MagicTrailer), 2)
trailer, err := shared.ReceiveBytes(port, len(shared.MagicTrailer), 2)
if err != nil {
*errorChan <- err
return
@ -201,25 +200,3 @@ func Receive(port *serial.Port, commandChan *chan datastructures.SignerRequest,
*commandChan <- *command
}
// receive the requested number of bytes from serial port and stop after the given timeout in seconds
func receiveBytes(port *serial.Port, count int, timeout time.Duration) ([]byte, error) {
timeoutCh := time.After(timeout * time.Second)
readCh := make(chan []byte, 1)
errCh := make(chan error, 1)
go func() {
data := make([]byte, count)
if _, err := io.ReadAtLeast(*port, data, count); err != nil {
errCh <- err
} else {
readCh <- data
}
}()
select {
case <-timeoutCh:
return nil, errors.New("timeout")
case err := <-errCh:
return nil, err
case data := <-readCh:
return data, nil
}
}