Migrate mdns functions from tpm helpers to this repo

because tpm has nothing to do with mdns.

TODO: Remove the functions from tpm helpers and bump the module here

Signed-off-by: Dimitris Karakasilis <dimitris@karakasilis.me>

cmd/discovery/client/client.go

@@ -16,6 +16,9 @@ import (
 	"github.com/mudler/yip/pkg/utils"
 )
 
+// Because of how go-pluggable works, we can't just print to stdout
+const LOGFILE = "/tmp/kcrypt-challenger-client.log"
+
 var errPartNotFound error = fmt.Errorf("pass for partition not found")
 var errBadCertificate error = fmt.Errorf("unknown certificate")
 
@@ -30,6 +33,10 @@ func NewClient() (*Client, error) {
 
 // ❯ echo '{ "data": "{ \\"label\\": \\"LABEL\\" }"}' | sudo -E WSS_SERVER="http://localhost:8082/challenge" ./challenger "discovery.password"
 func (c *Client) Start() error {
+	if err := os.RemoveAll(LOGFILE); err != nil { // Start fresh
+		return fmt.Errorf("removing the logfile: %w", err)
+	}
+
 	factory := pluggable.NewPluginFactory()
 
 	// Input: bus.EventInstallPayload
@@ -59,7 +66,7 @@ func (c *Client) Start() error {
 	return factory.Run(pluggable.EventType(os.Args[1]), os.Stdin, os.Stdout)
 }
 
-func (c *Client) generatePass(postEndpoint string, p *block.Partition) error {
+func (c *Client) generatePass(postEndpoint string, headers map[string]string, p *block.Partition) error {
 
 	rand := utils.RandomString(32)
 	pass, err := tpm.EncryptBlob([]byte(rand))
@@ -75,6 +82,10 @@ func (c *Client) generatePass(postEndpoint string, p *block.Partition) error {
 		tpm.WithAdditionalHeader("name", p.Name),
 		tpm.WithAdditionalHeader("uuid", p.UUID),
 	}
+	for k, v := range headers {
+		opts = append(opts, tpm.WithAdditionalHeader(k, v))
+	}
+
 	conn, err := tpm.Connection(postEndpoint, opts...)
 	if err != nil {
 		return err
@@ -84,20 +95,27 @@ func (c *Client) generatePass(postEndpoint string, p *block.Partition) error {
 }
 
 func (c *Client) waitPass(p *block.Partition, attempts int) (pass string, err error) {
-	// IF we don't have any server configured, just do local
+	additionalHeaders := map[string]string{}
-	if c.Config.Kcrypt.Challenger.Server == "" {
+	serverURL := c.Config.Kcrypt.Challenger.Server
+
+	// If we don't have any server configured, just do local
+	if serverURL == "" {
 		return localPass(c.Config)
 	}
 
-	challengeEndpoint := fmt.Sprintf("%s/getPass", c.Config.Kcrypt.Challenger.Server)
+	if c.Config.Kcrypt.Challenger.MDNS {
-	postEndpoint := fmt.Sprintf("%s/postPass", c.Config.Kcrypt.Challenger.Server)
+		serverURL, additionalHeaders, err = queryMDNS(serverURL)
+	}
+
+	getEndpoint := fmt.Sprintf("%s/getPass", serverURL)
+	postEndpoint := fmt.Sprintf("%s/postPass", serverURL)
 
 	for tries := 0; tries < attempts; tries++ {
 		var generated bool
-		pass, generated, err = getPass(challengeEndpoint, c.Config.Kcrypt.Challenger.Certificate, p)
+		pass, generated, err = getPass(getEndpoint, additionalHeaders, c.Config.Kcrypt.Challenger.Certificate, p)
 		if err == errPartNotFound {
 			// IF server doesn't have a pass for us, then we generate one and we set it
-			err = c.generatePass(postEndpoint, p)
+			err = c.generatePass(postEndpoint, additionalHeaders, p)
 			if err != nil {
 				return
 			}
@@ -118,7 +136,7 @@ func (c *Client) waitPass(p *block.Partition, attempts int) (pass string, err er
 			return
 		}
 
-		fmt.Printf("Failed with error: %s . Will retry.\n", err.Error())
+		logToFile("Failed with error: %s . Will retry.\n", err.Error())
 		time.Sleep(1 * time.Second) // network errors? retry
 	}
 
@@ -145,3 +163,14 @@ func (c *Client) decryptPassphrase(pass string) (string, error) {
 
 	return string(passBytes), err
 }
+
+func logToFile(format string, a ...any) {
+	s := fmt.Sprintf(format, a...)
+	file, err := os.OpenFile(LOGFILE, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
+	if err != nil {
+		panic(err)
+	}
+	defer file.Close()
+
+	file.WriteString(s)
+}

cmd/discovery/client/config.go

@@ -13,11 +13,10 @@ type Client struct {
 type Config struct {
 	Kcrypt struct {
 		Challenger struct {
+			MDNS        bool   `yaml:"mdns,omitempty"`
 			Server      string `yaml:"challenger_server,omitempty"`
-			// Non-volatile index memory: where we store the encrypted passphrase (offline mode)
+			NVIndex     string `yaml:"nv_index,omitempty"` // Non-volatile index memory: where we store the encrypted passphrase (offline mode)
-			NVIndex string `yaml:"nv_index,omitempty"`
+			CIndex      string `yaml:"c_index,omitempty"`  // Certificate index: this is where the rsa pair that decrypts the passphrase lives
-			// Certificate index: this is where the rsa pair that decrypts the passphrase lives
-			CIndex      string `yaml:"c_index,omitempty"`
 			TPMDevice   string `yaml:"tpm_device,omitempty"`
 			Certificate string `yaml:"certificate,omitempty"`
 		}

cmd/discovery/client/enc.go

@@ -16,13 +16,19 @@ import (
 
 const DefaultNVIndex = "0x1500000"
 
-func getPass(server, certificate string, partition *block.Partition) (string, bool, error) {
+func getPass(server string, headers map[string]string, certificate string, partition *block.Partition) (string, bool, error) {
-	msg, err := tpm.Get(server,
+	opts := []tpm.Option{
 		tpm.WithCAs([]byte(certificate)),
 		tpm.AppendCustomCAToSystemCA,
 		tpm.WithAdditionalHeader("label", partition.FilesystemLabel),
 		tpm.WithAdditionalHeader("name", partition.Name),
-		tpm.WithAdditionalHeader("uuid", partition.UUID))
+		tpm.WithAdditionalHeader("uuid", partition.UUID),
+	}
+	for k, v := range headers {
+		opts = append(opts, tpm.WithAdditionalHeader(k, v))
+	}
+
+	msg, err := tpm.Get(server, opts...)
 	if err != nil {
 		return "", false, err
 	}

cmd/discovery/client/mdns.go

@@ -0,0 +1,85 @@
+package client
+
+import (
+	"fmt"
+	"net/url"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/hashicorp/mdns"
+)
+
+const (
+	MDNSServiceType = "_kcrypt._tcp"
+	MDNSTimeout     = 15 * time.Second
+)
+
+// queryMDNS will make an mdns query on local network to find a kcrypt challenger server
+// instance. If none is found, the original URL is returned and no additional headers.
+// If a response is received, the IP address and port from the response will be returned// and an additional "Host" header pointing to the original host.
+func queryMDNS(originalURL string) (string, map[string]string, error) {
+	additionalHeaders := map[string]string{}
+	var err error
+
+	parsedURL, err := url.Parse(originalURL)
+	if err != nil {
+		return originalURL, additionalHeaders, fmt.Errorf("parsing the original host: %w", err)
+	}
+
+	host := parsedURL.Host
+	if !strings.HasSuffix(host, ".local") { // sanity check
+		return "", additionalHeaders, fmt.Errorf("domain should end in \".local\" when using mdns")
+	}
+
+	mdnsIP, mdnsPort := discoverMDNSServer(host)
+	if mdnsIP == "" { // no reply
+		logToFile("no reply from mdns\n")
+		return originalURL, additionalHeaders, nil
+	}
+
+	additionalHeaders["Host"] = parsedURL.Host
+	newURL := strings.ReplaceAll(originalURL, host, mdnsIP)
+	// Remove any port in the original url
+	if port := parsedURL.Port(); port != "" {
+		newURL = strings.ReplaceAll(newURL, port, "")
+	}
+
+	// Add any possible port from the mdns response
+	if mdnsPort != "" {
+		newURL = strings.ReplaceAll(newURL, mdnsIP, fmt.Sprintf("%s:%s", mdnsIP, mdnsPort))
+	}
+
+	return newURL, additionalHeaders, nil
+}
+
+// discoverMDNSServer performs an mDNS query to discover any running kcrypt challenger
+// servers on the same network that matches the given hostname.
+// If a response if received, the IP address and the Port from the response are returned.
+func discoverMDNSServer(hostname string) (string, string) {
+	// Make a channel for results and start listening
+	entriesCh := make(chan *mdns.ServiceEntry, 4)
+	defer close(entriesCh)
+
+	logToFile("Will now wait for some mdns server to respond\n")
+	// Start the lookup. It will block until we read from the chan.
+	mdns.Lookup(MDNSServiceType, entriesCh)
+
+	expectedHost := hostname + "." // FQDN
+	// Wait until a matching server is found or we reach a timeout
+	for {
+		select {
+		case entry := <-entriesCh:
+			logToFile("mdns response received\n")
+			if entry.Host == expectedHost {
+				logToFile("%s matches %s\n", entry.Host, expectedHost)
+				return entry.AddrV4.String(), strconv.Itoa(entry.Port) // TODO: v6?
+			} else {
+				logToFile("%s didn't match %s\n", entry.Host, expectedHost)
+			}
+		case <-time.After(MDNSTimeout):
+			logToFile("timed out waiting for mdns\n")
+			return "", ""
+		}
+	}
+}

go.mod

@@ -6,10 +6,11 @@ require (
 	github.com/go-logr/logr v1.2.4
 	github.com/google/uuid v1.3.0
 	github.com/gorilla/websocket v1.5.0
+	github.com/hashicorp/mdns v1.0.5
 	github.com/jaypipes/ghw v0.11.0
 	github.com/kairos-io/kairos-sdk v0.0.15
 	github.com/kairos-io/kcrypt v0.7.0
-	github.com/kairos-io/tpm-helpers v0.0.0-20231220125202-70a0b64e5111
+	github.com/kairos-io/tpm-helpers v0.0.0-20240123063624-f7a3fcc66199
 	github.com/mudler/go-pluggable v0.0.0-20230126220627-7710299a0ae5
 	github.com/mudler/go-processmanager v0.0.0-20220724164624-c45b5c61312d
 	github.com/mudler/yip v1.3.0
@@ -85,7 +86,6 @@ require (
 	github.com/gookit/color v1.5.3 // indirect
 	github.com/hashicorp/errwrap v1.1.0 // indirect
 	github.com/hashicorp/go-multierror v1.1.1 // indirect
-	github.com/hashicorp/mdns v1.0.5 // indirect
 	github.com/huandu/xstrings v1.3.3 // indirect
 	github.com/imdario/mergo v0.3.15 // indirect
 	github.com/ipfs/go-log v1.0.5 // indirect

go.sum

@@ -415,8 +415,8 @@ github.com/kairos-io/kairos-sdk v0.0.15 h1:1hcnRfKlBzDWcZ8z7UrUqJ2v6GafCHZknPqm9
 github.com/kairos-io/kairos-sdk v0.0.15/go.mod h1:Ew3NKFuXByu3Y3yGu8Q92M3oMqsXrg2VilouubdhYqA=
 github.com/kairos-io/kcrypt v0.7.0 h1:ESmCBIFbBBv7mJf0/f6ugqwSvz63M5oP9sUIdHiDlLc=
 github.com/kairos-io/kcrypt v0.7.0/go.mod h1:a9eI+vPVIQHPRtqEV/O/yIfDOdMWd9epVrq1p94gccM=
-github.com/kairos-io/tpm-helpers v0.0.0-20231220125202-70a0b64e5111 h1:iEBUZdneuS3YfRunKmRpxfCe4XBxeSiBcIXRmNcUzrw=
+github.com/kairos-io/tpm-helpers v0.0.0-20240123063624-f7a3fcc66199 h1:eXiZNiQfZDelYfTF733IxDOKGAKJqn0fF0kFY10QreU=
-github.com/kairos-io/tpm-helpers v0.0.0-20231220125202-70a0b64e5111/go.mod h1:mxKPLc7DQu9bcL8hv8A5PqTSH/rWm0M7SGolwYRYJq4=
+github.com/kairos-io/tpm-helpers v0.0.0-20240123063624-f7a3fcc66199/go.mod h1:6YGebKVrPoJGBd9QE+x4zyuo3vPw1y33iQkNChjlBo8=
 github.com/kisielk/errcheck v1.1.0/go.mod h1:EZBBE59ingxPouuu3KfxchcWSUPOHkagtvWXihfKN4Q=
 github.com/kisielk/errcheck v1.2.0/go.mod h1:/BMXB+zMLi60iA8Vv6Ksmxu/1UDYcXs4uQLJ+jE2L00=
 github.com/kisielk/errcheck v1.5.0/go.mod h1:pFxgyoBC7bSaBwPgfKdkLd5X25qrDl4LWUI2bnpBCr8=

mdns-notes.md

@@ -17,19 +17,23 @@ k3d cluster create kcrypt -p '30000:30000@server:0'
 ```
 helm repo add kairos https://kairos-io.github.io/helm-charts
 helm install kairos-crd kairos/kairos-crds
-helm install kairos-challenger kairos/kairos-challenger
 ```
 
-- Edit the challenger service `kairos-challenger-escrow-service` and change it to NodePort (or do it through the helm chart when installing)
+Create the following 'kcrypt-challenger-values.yaml` file:
 
-```
+
-  ports:
+```yaml
-  - name: wss
+service:
+  challenger:
+    type: "NodePort"
     port: 8082
-    protocol: TCP
-    targetPort: 8082
     nodePort: 30000
-  type: NodePort
+```
+
+and deploy the challenger server with it:
+
+```bash
+helm install -f kcrypt-challenger-values.yaml kairos-challenger kairos/kairos-challenger
 ```
 
 - Add the sealedvolume and secret for the tpm chip:
@@ -52,7 +56,7 @@ metadata:
 spec:
   TPMHash: "5640e37f4016da16b841a93880dcc44886904392fa3c86681087b77db5afedbe"
   partitions:
-    - label: "persistent"
+    - label: COS_PERSISTENT
       secret:
         name: example-host-tpm-secret
         path: pass
@@ -62,7 +66,7 @@ spec:
 - Start the [simple-mdns-server](https://github.com/kairos-io/simple-mdns-server)
 
 ```
-go run . --port 30000 --interfaceName enp121s0 --serviceType _kcrypt._tcp
+go run . --port 30000 --interfaceName enp121s0 --serviceType _kcrypt._tcp --hostName mychallenger.local
 ```
 
 
@@ -86,7 +90,7 @@ install:
 # Kcrypt configuration block
 kcrypt:
   challenger:
-    challenger_server: "http://doesnt-matter-the-name.local"
+    challenger_server: "http://mychallenger.local"
 ```
 
 - Install: