ssntp: Add smart default certificates finding

This change adds value to our Zero Configuration approach in CIAO
project. It sets --cacert and --cert as optional parameters.

Examples:
- When starting ciao-launcher:
   $ ciao-launcher
- When starting ciao-controller:
   $ ciao-controller

That's all, no more args. SSNTP certificates are auto-discovered
from /etc/pki/ciao path. It's important to mention that, if we
have more than 1 SSNTP certificate, it will fail.

Signed-off-by: Munoz, Obed N <[email protected]>

ciao-controller/controller_test.go

@@ -782,8 +782,8 @@ func TestMain(m *testing.M) {
 
 	config := &ssntp.Config{
 		URI:    "localhost",
-		CAcert: *caCert,
-		Cert:   *cert,
+		CAcert: ssntp.DefaultCACert,
+		Cert:   ssntp.RoleToDefaultCertName(ssntp.Controller),
 	}
 
 	context.client, err = newSSNTPClient(context, config)

ciao-controller/main.go

@@ -35,8 +35,8 @@ type controller struct {
 }
 
 var singleMachine = flag.Bool("single", false, "Enable single machine test")
-var cert = flag.String("cert", ssntp.RoleToDefaultCertName(ssntp.Controller), "Client certificate")
-var caCert = flag.String("cacert", ssntp.DefaultCACert, "CA certificate")
+var cert = flag.String("cert", "", "Client certificate")
+var caCert = flag.String("cacert", "", "CA certificate")
 var serverURL = flag.String("url", "", "Server URL")
 var identityURL = "identity:35357"
 var serviceUser = "csr"

ciao-launcher/main.go

@@ -95,8 +95,8 @@ var simulate bool
 var maxInstances = int(math.MaxInt32)
 
 func init() {
-	flag.StringVar(&serverCertPath, "cacert", "/etc/pki/ciao/CAcert-server-localhost.pem", "Client certificate")
-	flag.StringVar(&clientCertPath, "cert", "/etc/pki/ciao/cert-client-localhost.pem", "CA certificate")
+	flag.StringVar(&serverCertPath, "cacert", "", "Client certificate")
+	flag.StringVar(&clientCertPath, "cert", "", "CA certificate")
 	flag.Var(&networking, "network", "Can be none, cn (compute node) or nn (network node)")
 	flag.BoolVar(&hardReset, "hard-reset", false, "Kill and delete all instances, reset networking and exit")
 	flag.BoolVar(&simulate, "simulation", false, "Launcher simulation")

ssntp/ssntp.go

@@ -27,6 +27,7 @@ import (
 	"io/ioutil"
 	"log"
 	"os"
+	"path/filepath"
 	"strings"
 	"sync"
 	"syscall"
@@ -710,6 +711,9 @@ const defaultServerCert = "/etc/pki/ciao/cert-Server-localhost.pem"
 const defaultClientCert = "/etc/pki/ciao/client.pem"
 const defaultSchedulerCert = "/etc/pki/ciao/cert-Scheduler-localhost.pem"
 
+// Default CIAO certs path
+const ciaoCertsPath = "/etc/pki/ciao/*"
+
 // RoleToDefaultCertName returns default certificate names for each SSNTP role
 func RoleToDefaultCertName(role Role) string {
 	switch role {
@@ -1151,13 +1155,88 @@ func (config *Config) port() uint32 {
 	return port
 }
 
-func (config *Config) setCerts() {
-	if config.CAcert == "" {
-		config.CAcert = DefaultCACert
+func loadCertificate(certPath string) (*x509.Certificate, error) {
+	certPEM, err := ioutil.ReadFile(certPath)
+	if err != nil {
+		return nil, err
+	}
+	block, _ := pem.Decode(certPEM)
+	if block == nil {
+		return nil, fmt.Errorf("Failed to parse certificate PEM")
+	}
+	cert, err := x509.ParseCertificate(block.Bytes)
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse certificate: %v", err)
+	}
+	return cert, nil
+}
+
+func getDefaultCertificate() (cacert, cert string, err error) {
+	certs := []string{}
+
+	files, err := filepath.Glob(ciaoCertsPath)
+	if err != nil {
+		return "", "", err
+	}
+
+certsLoop:
+	for _, file := range files {
+		cert, err := loadCertificate(file)
+		if err != nil {
+			continue certsLoop
+		}
+		if cacert == "" {
+			if cert.IsCA == true {
+				cacert = file
+				continue certsLoop
+			}
+		}
+		role := GetRoleFromOIDs(cert.UnknownExtKeyUsage)
+		if role != UNKNOWN {
+			certs = append(certs, file)
+		}
 	}
 
-	if config.Cert == "" {
-		config.Cert = defaultClientCert
+	if len(certs) > 1 {
+		_, err := os.Stat(DefaultCACert)
+		if os.IsNotExist(err) {
+			return "", "", fmt.Errorf("More than one cert files at: %s", ciaoCertsPath)
+		}
+
+		_, err = os.Stat(defaultClientCert)
+		if os.IsNotExist(err) {
+			return "", "", fmt.Errorf("More than one cert files at: %s", ciaoCertsPath)
+		}
+
+		return DefaultCACert, defaultClientCert, nil
+	} else if len(certs) == 0 {
+		return "", "", fmt.Errorf("%s Certificates are not found", ciaoCertsPath)
+	}
+
+	certPEM, err := ioutil.ReadFile(cacert)
+	certPool := x509.NewCertPool()
+	certPool.AppendCertsFromPEM(certPEM)
+	vOpts := x509.VerifyOptions{Roots: certPool}
+
+	clientCert, err := loadCertificate(certs[0])
+	if err != nil {
+		return "", "", err
+	}
+	_, err = clientCert.Verify(vOpts)
+	if err != nil {
+		return "", "", err
+	}
+
+	return cacert, certs[0], nil
+}
+
+func (config *Config) setCerts() {
+	var err error
+	if config.CAcert == "" {
+		config.CAcert, config.Cert, err = getDefaultCertificate()
+		if err != nil {
+			log.Fatal(err)
+		}
 	}
 }