331 lines
9.3 KiB
Go
331 lines
9.3 KiB
Go
package opcua_client
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import (
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"crypto/ecdsa"
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"crypto/rand"
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"crypto/rsa"
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"crypto/tls"
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"crypto/x509"
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"crypto/x509/pkix"
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"encoding/pem"
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"fmt"
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"io/ioutil"
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"log"
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"math/big"
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"net"
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"net/url"
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"os"
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"strings"
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"time"
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"github.com/gopcua/opcua"
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"github.com/gopcua/opcua/debug"
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"github.com/gopcua/opcua/ua"
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"github.com/pkg/errors"
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)
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// SELF SIGNED CERT FUNCTIONS
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func newTempDir() (string, error) {
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dir, err := ioutil.TempDir("", "ssc")
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return dir, err
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}
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func generateCert(host string, rsaBits int, certFile, keyFile string, dur time.Duration) (string, string) {
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dir, _ := newTempDir()
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if len(host) == 0 {
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log.Fatalf("Missing required host parameter")
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}
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if rsaBits == 0 {
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rsaBits = 2048
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}
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if len(certFile) == 0 {
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certFile = fmt.Sprintf("%s/cert.pem", dir)
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}
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if len(keyFile) == 0 {
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keyFile = fmt.Sprintf("%s/key.pem", dir)
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}
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priv, err := rsa.GenerateKey(rand.Reader, rsaBits)
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if err != nil {
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log.Fatalf("failed to generate private key: %s", err)
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}
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notBefore := time.Now()
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notAfter := notBefore.Add(dur)
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serialNumberLimit := new(big.Int).Lsh(big.NewInt(1), 128)
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serialNumber, err := rand.Int(rand.Reader, serialNumberLimit)
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if err != nil {
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log.Fatalf("failed to generate serial number: %s", err)
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}
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template := x509.Certificate{
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SerialNumber: serialNumber,
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Subject: pkix.Name{
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Organization: []string{"Telegraf OPC UA client"},
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},
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NotBefore: notBefore,
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NotAfter: notAfter,
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KeyUsage: x509.KeyUsageContentCommitment | x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature | x509.KeyUsageDataEncipherment | x509.KeyUsageCertSign,
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ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth, x509.ExtKeyUsageClientAuth},
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BasicConstraintsValid: true,
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}
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hosts := strings.Split(host, ",")
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for _, h := range hosts {
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if ip := net.ParseIP(h); ip != nil {
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template.IPAddresses = append(template.IPAddresses, ip)
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} else {
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template.DNSNames = append(template.DNSNames, h)
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}
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if uri, err := url.Parse(h); err == nil {
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template.URIs = append(template.URIs, uri)
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}
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}
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derBytes, err := x509.CreateCertificate(rand.Reader, &template, &template, publicKey(priv), priv)
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if err != nil {
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log.Fatalf("Failed to create certificate: %s", err)
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}
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certOut, err := os.Create(certFile)
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if err != nil {
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log.Fatalf("failed to open %s for writing: %s", certFile, err)
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}
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if err := pem.Encode(certOut, &pem.Block{Type: "CERTIFICATE", Bytes: derBytes}); err != nil {
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log.Fatalf("failed to write data to %s: %s", certFile, err)
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}
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if err := certOut.Close(); err != nil {
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log.Fatalf("error closing %s: %s", certFile, err)
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}
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keyOut, err := os.OpenFile(keyFile, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
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if err != nil {
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log.Printf("failed to open %s for writing: %s", keyFile, err)
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return "", ""
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}
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if err := pem.Encode(keyOut, pemBlockForKey(priv)); err != nil {
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log.Fatalf("failed to write data to %s: %s", keyFile, err)
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}
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if err := keyOut.Close(); err != nil {
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log.Fatalf("error closing %s: %s", keyFile, err)
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}
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return certFile, keyFile
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}
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func publicKey(priv interface{}) interface{} {
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switch k := priv.(type) {
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case *rsa.PrivateKey:
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return &k.PublicKey
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case *ecdsa.PrivateKey:
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return &k.PublicKey
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default:
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return nil
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}
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}
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func pemBlockForKey(priv interface{}) *pem.Block {
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switch k := priv.(type) {
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case *rsa.PrivateKey:
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return &pem.Block{Type: "RSA PRIVATE KEY", Bytes: x509.MarshalPKCS1PrivateKey(k)}
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case *ecdsa.PrivateKey:
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b, err := x509.MarshalECPrivateKey(k)
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if err != nil {
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fmt.Fprintf(os.Stderr, "Unable to marshal ECDSA private key: %v", err)
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os.Exit(2)
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}
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return &pem.Block{Type: "EC PRIVATE KEY", Bytes: b}
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default:
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return nil
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}
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}
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// OPT FUNCTIONS
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func generateClientOpts(endpoints []*ua.EndpointDescription, certFile, keyFile, policy, mode, auth, username, password string) []opcua.Option {
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opts := []opcua.Option{}
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appuri := "urn:telegraf:gopcua:client"
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appname := "Telegraf"
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// ApplicationURI is automatically read from the cert so is not required if a cert if provided
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opts = append(opts, opcua.ApplicationURI(appuri))
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opts = append(opts, opcua.ApplicationName(appname))
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if certFile == "" && keyFile == "" {
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if policy != "None" || mode != "None" {
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certFile, keyFile = generateCert(appuri, 2048, certFile, keyFile, (365 * 24 * time.Hour))
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}
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}
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var cert []byte
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if certFile != "" && keyFile != "" {
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debug.Printf("Loading cert/key from %s/%s", certFile, keyFile)
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c, err := tls.LoadX509KeyPair(certFile, keyFile)
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if err != nil {
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log.Printf("Failed to load certificate: %s", err)
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} else {
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pk, ok := c.PrivateKey.(*rsa.PrivateKey)
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if !ok {
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log.Fatalf("Invalid private key")
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}
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cert = c.Certificate[0]
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opts = append(opts, opcua.PrivateKey(pk), opcua.Certificate(cert))
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}
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}
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var secPolicy string
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switch {
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case policy == "auto":
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// set it later
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case strings.HasPrefix(policy, ua.SecurityPolicyURIPrefix):
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secPolicy = policy
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policy = ""
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case policy == "None" || policy == "Basic128Rsa15" || policy == "Basic256" || policy == "Basic256Sha256" || policy == "Aes128_Sha256_RsaOaep" || policy == "Aes256_Sha256_RsaPss":
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secPolicy = ua.SecurityPolicyURIPrefix + policy
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policy = ""
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default:
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log.Fatalf("Invalid security policy: %s", policy)
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}
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// Select the most appropriate authentication mode from server capabilities and user input
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authMode, authOption := generateAuth(auth, cert, username, password)
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opts = append(opts, authOption)
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var secMode ua.MessageSecurityMode
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switch strings.ToLower(mode) {
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case "auto":
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case "none":
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secMode = ua.MessageSecurityModeNone
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mode = ""
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case "sign":
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secMode = ua.MessageSecurityModeSign
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mode = ""
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case "signandencrypt":
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secMode = ua.MessageSecurityModeSignAndEncrypt
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mode = ""
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default:
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log.Fatalf("Invalid security mode: %s", mode)
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}
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// Allow input of only one of sec-mode,sec-policy when choosing 'None'
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if secMode == ua.MessageSecurityModeNone || secPolicy == ua.SecurityPolicyURINone {
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secMode = ua.MessageSecurityModeNone
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secPolicy = ua.SecurityPolicyURINone
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}
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// Find the best endpoint based on our input and server recommendation (highest SecurityMode+SecurityLevel)
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var serverEndpoint *ua.EndpointDescription
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switch {
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case mode == "auto" && policy == "auto": // No user selection, choose best
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for _, e := range endpoints {
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if serverEndpoint == nil || (e.SecurityMode >= serverEndpoint.SecurityMode && e.SecurityLevel >= serverEndpoint.SecurityLevel) {
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serverEndpoint = e
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}
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}
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case mode != "auto" && policy == "auto": // User only cares about mode, select highest securitylevel with that mode
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for _, e := range endpoints {
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if e.SecurityMode == secMode && (serverEndpoint == nil || e.SecurityLevel >= serverEndpoint.SecurityLevel) {
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serverEndpoint = e
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}
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}
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case mode == "auto" && policy != "auto": // User only cares about policy, select highest securitylevel with that policy
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for _, e := range endpoints {
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if e.SecurityPolicyURI == secPolicy && (serverEndpoint == nil || e.SecurityLevel >= serverEndpoint.SecurityLevel) {
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serverEndpoint = e
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}
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}
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default: // User cares about both
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for _, e := range endpoints {
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if e.SecurityPolicyURI == secPolicy && e.SecurityMode == secMode && (serverEndpoint == nil || e.SecurityLevel >= serverEndpoint.SecurityLevel) {
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serverEndpoint = e
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}
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}
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}
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if serverEndpoint == nil { // Didn't find an endpoint with matching policy and mode.
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log.Printf("unable to find suitable server endpoint with selected sec-policy and sec-mode")
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log.Fatalf("quitting")
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}
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secPolicy = serverEndpoint.SecurityPolicyURI
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secMode = serverEndpoint.SecurityMode
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// Check that the selected endpoint is a valid combo
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err := validateEndpointConfig(endpoints, secPolicy, secMode, authMode)
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if err != nil {
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log.Fatalf("error validating input: %s", err)
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}
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opts = append(opts, opcua.SecurityFromEndpoint(serverEndpoint, authMode))
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return opts
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}
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func generateAuth(a string, cert []byte, un, pw string) (ua.UserTokenType, opcua.Option) {
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var err error
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var authMode ua.UserTokenType
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var authOption opcua.Option
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switch strings.ToLower(a) {
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case "anonymous":
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authMode = ua.UserTokenTypeAnonymous
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authOption = opcua.AuthAnonymous()
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case "username":
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authMode = ua.UserTokenTypeUserName
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if un == "" {
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if err != nil {
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log.Fatalf("error reading username input: %s", err)
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}
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}
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if pw == "" {
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if err != nil {
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log.Fatalf("error reading username input: %s", err)
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}
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}
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authOption = opcua.AuthUsername(un, pw)
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case "certificate":
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authMode = ua.UserTokenTypeCertificate
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authOption = opcua.AuthCertificate(cert)
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case "issuedtoken":
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// todo: this is unsupported, fail here or fail in the opcua package?
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authMode = ua.UserTokenTypeIssuedToken
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authOption = opcua.AuthIssuedToken([]byte(nil))
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default:
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log.Printf("unknown auth-mode, defaulting to Anonymous")
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authMode = ua.UserTokenTypeAnonymous
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authOption = opcua.AuthAnonymous()
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}
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return authMode, authOption
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}
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func validateEndpointConfig(endpoints []*ua.EndpointDescription, secPolicy string, secMode ua.MessageSecurityMode, authMode ua.UserTokenType) error {
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for _, e := range endpoints {
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if e.SecurityMode == secMode && e.SecurityPolicyURI == secPolicy {
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for _, t := range e.UserIdentityTokens {
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if t.TokenType == authMode {
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return nil
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}
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}
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}
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}
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err := errors.Errorf("server does not support an endpoint with security : %s , %s", secPolicy, secMode)
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return err
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}
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