refactor: Minimise duplicated client TSIG code

gss/apcera.go

@@ -71,24 +71,7 @@ func (c *Client) Close() error {
 	return multierror.Append(c.close(), c.lib.Unload())
 }
 
-// Generate generates the TSIG MAC based on the established context.
-// It is called with the bytes of the DNS message, and the partial TSIG
-// record containing the algorithm and name which is the negotiated TKEY
-// for this context.
-// It returns the bytes for the TSIG MAC and any error that occurred.
-func (c *Client) Generate(msg []byte, t *dns.TSIG) (b []byte, err error) {
-	if dns.CanonicalName(t.Algorithm) != tsig.GSS {
-		return nil, dns.ErrKeyAlg
-	}
-
-	c.m.RLock()
-	defer c.m.RUnlock()
-
-	ctx, ok := c.ctx[t.Hdr.Name]
-	if !ok {
-		return nil, dns.ErrSecret
-	}
-
+func (c *Client) generate(ctx *gssapi.CtxId, msg []byte) ([]byte, error) {
 	message, err := c.lib.MakeBufferBytes(msg)
 	if err != nil {
 		return nil, err
@@ -110,24 +93,7 @@ func (c *Client) Generate(msg []byte, t *dns.TSIG) (b []byte, err error) {
 	return token.Bytes(), nil
 }
 
-// Verify verifies the TSIG MAC based on the established context.
-// It is called with the bytes of the DNS message, and the TSIG record
-// containing the algorithm, MAC, and name which is the negotiated TKEY
-// for this context.
-// It returns any error that occurred.
-func (c *Client) Verify(stripped []byte, t *dns.TSIG) (err error) {
-	if dns.CanonicalName(t.Algorithm) != tsig.GSS {
-		return dns.ErrKeyAlg
-	}
-
-	c.m.RLock()
-	defer c.m.RUnlock()
-
-	ctx, ok := c.ctx[t.Hdr.Name]
-	if !ok {
-		return dns.ErrSecret
-	}
-
+func (c *Client) verify(ctx *gssapi.CtxId, stripped, mac []byte) error {
 	// Turn the TSIG-stripped message bytes into a *gssapi.Buffer
 	message, err := c.lib.MakeBufferBytes(stripped)
 	if err != nil {
@@ -138,11 +104,6 @@ func (c *Client) Verify(stripped []byte, t *dns.TSIG) (err error) {
 		err = multierror.Append(err, message.Release()).ErrorOrNil()
 	}()
 
-	mac, err := hex.DecodeString(t.MAC)
-	if err != nil {
-		return err
-	}
-
 	// Turn the TSIG MAC bytes into a *gssapi.Buffer
 	token, err := c.lib.MakeBufferBytes(mac)
 	if err != nil {

gss/client.go

@@ -0,0 +1,106 @@
+package gss
+
+import (
+	"encoding/hex"
+
+	"github.com/bodgit/tsig"
+	"github.com/go-logr/logr"
+	multierror "github.com/hashicorp/go-multierror"
+	"github.com/miekg/dns"
+)
+
+var _ dns.TsigProvider = new(Client)
+
+// Generate generates the TSIG MAC based on the established context.
+// It is called with the bytes of the DNS message, and the partial TSIG
+// record containing the algorithm and name which is the negotiated TKEY
+// for this context.
+// It returns the bytes for the TSIG MAC and any error that occurred.
+func (c *Client) Generate(msg []byte, t *dns.TSIG) ([]byte, error) {
+	if dns.CanonicalName(t.Algorithm) != tsig.GSS {
+		return nil, dns.ErrKeyAlg
+	}
+
+	c.m.RLock()
+	defer c.m.RUnlock()
+
+	ctx, ok := c.ctx[t.Hdr.Name]
+	if !ok {
+		return nil, dns.ErrSecret
+	}
+
+	return c.generate(ctx, msg)
+}
+
+// Verify verifies the TSIG MAC based on the established context.
+// It is called with the bytes of the DNS message, and the TSIG record
+// containing the algorithm, MAC, and name which is the negotiated TKEY
+// for this context.
+// It returns any error that occurred.
+func (c *Client) Verify(stripped []byte, t *dns.TSIG) error {
+	if dns.CanonicalName(t.Algorithm) != tsig.GSS {
+		return dns.ErrKeyAlg
+	}
+
+	c.m.RLock()
+	defer c.m.RUnlock()
+
+	ctx, ok := c.ctx[t.Hdr.Name]
+	if !ok {
+		return dns.ErrSecret
+	}
+
+	mac, err := hex.DecodeString(t.MAC)
+	if err != nil {
+		return err
+	}
+
+	return c.verify(ctx, stripped, mac)
+}
+
+func (c *Client) close() error {
+	c.m.RLock()
+
+	keys := make([]string, 0, len(c.ctx))
+	for k := range c.ctx {
+		keys = append(keys, k)
+	}
+
+	c.m.RUnlock()
+
+	var errs error
+	for _, k := range keys {
+		errs = multierror.Append(errs, c.DeleteContext(k))
+	}
+
+	return errs
+}
+
+func (c *Client) setOption(options ...func(*Client) error) error {
+	for _, option := range options {
+		if err := option(c); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// SetConfig sets the Kerberos configuration used by c.
+func (c *Client) SetConfig(config string) error {
+	return c.setOption(WithConfig(config))
+}
+
+// WithLogger sets the logger used.
+func WithLogger(logger logr.Logger) func(*Client) error {
+	return func(c *Client) error {
+		c.logger = logger.WithName("client")
+
+		return nil
+	}
+}
+
+// SetLogger sets the logger used by c.
+func (c *Client) SetLogger(logger logr.Logger) error {
+	return c.setOption(WithLogger(logger))
+}

gss/gokrb5.go

@@ -67,50 +67,11 @@ func (c *Client) Close() error {
 	return c.close()
 }
 
-// Generate generates the TSIG MAC based on the established context.
-// It is called with the bytes of the DNS message, and the partial TSIG
-// record containing the algorithm and name which is the negotiated TKEY
-// for this context.
-// It returns the bytes for the TSIG MAC and any error that occurred.
-func (c *Client) Generate(msg []byte, t *dns.TSIG) ([]byte, error) {
-	if dns.CanonicalName(t.Algorithm) != tsig.GSS {
-		return nil, dns.ErrKeyAlg
-	}
-
-	c.m.RLock()
-	defer c.m.RUnlock()
-
-	ctx, ok := c.ctx[t.Hdr.Name]
-	if !ok {
-		return nil, dns.ErrSecret
-	}
-
+func (c *Client) generate(ctx *wrapper.Initiator, msg []byte) ([]byte, error) {
 	return ctx.MakeSignature(msg)
 }
 
-// Verify verifies the TSIG MAC based on the established context.
-// It is called with the bytes of the DNS message, and the TSIG record
-// containing the algorithm, MAC, and name which is the negotiated TKEY
-// for this context.
-// It returns any error that occurred.
-func (c *Client) Verify(stripped []byte, t *dns.TSIG) error {
-	if dns.CanonicalName(t.Algorithm) != tsig.GSS {
-		return dns.ErrKeyAlg
-	}
-
-	c.m.RLock()
-	defer c.m.RUnlock()
-
-	ctx, ok := c.ctx[t.Hdr.Name]
-	if !ok {
-		return dns.ErrSecret
-	}
-
-	mac, err := hex.DecodeString(t.MAC)
-	if err != nil {
-		return err
-	}
-
+func (c *Client) verify(ctx *wrapper.Initiator, stripped, mac []byte) error {
 	return ctx.VerifySignature(stripped, mac)
 }
 

gss/gss.go

@@ -78,8 +78,6 @@ import (
 	"math/big"
 
 	"github.com/bodgit/tsig"
-	"github.com/go-logr/logr"
-	multierror "github.com/hashicorp/go-multierror"
 	"github.com/miekg/dns"
 )
 
@@ -129,50 +127,3 @@ func generateSPN(host string) string {
 
 	return fmt.Sprintf("DNS/%s", host)
 }
-
-func (c *Client) close() error {
-	c.m.RLock()
-
-	keys := make([]string, 0, len(c.ctx))
-	for k := range c.ctx {
-		keys = append(keys, k)
-	}
-
-	c.m.RUnlock()
-
-	var errs error
-	for _, k := range keys {
-		errs = multierror.Append(errs, c.DeleteContext(k))
-	}
-
-	return errs
-}
-
-func (c *Client) setOption(options ...func(*Client) error) error {
-	for _, option := range options {
-		if err := option(c); err != nil {
-			return err
-		}
-	}
-
-	return nil
-}
-
-// SetConfig sets the Kerberos configuration used by c.
-func (c *Client) SetConfig(config string) error {
-	return c.setOption(WithConfig(config))
-}
-
-// WithLogger sets the logger used.
-func WithLogger(logger logr.Logger) func(*Client) error {
-	return func(c *Client) error {
-		c.logger = logger.WithName("client")
-
-		return nil
-	}
-}
-
-// SetLogger sets the logger used by c.
-func (c *Client) SetLogger(logger logr.Logger) error {
-	return c.setOption(WithLogger(logger))
-}

gss/sspi.go

@@ -65,60 +65,14 @@ func (c *Client) Close() error {
 	return c.close()
 }
 
-// Generate generates the TSIG MAC based on the established context.
-// It is called with the bytes of the DNS message, and the partial TSIG
-// record containing the algorithm and name which is the negotiated TKEY
-// for this context.
-// It returns the bytes for the TSIG MAC and any error that occurred.
-func (c *Client) Generate(msg []byte, t *dns.TSIG) ([]byte, error) {
-	if dns.CanonicalName(t.Algorithm) != tsig.GSS {
-		return nil, dns.ErrKeyAlg
-	}
-
-	c.m.RLock()
-	defer c.m.RUnlock()
-
-	ctx, ok := c.ctx[t.Hdr.Name]
-	if !ok {
-		return nil, dns.ErrSecret
-	}
-
-	token, err := ctx.MakeSignature(msg, 0, 0)
-	if err != nil {
-		return nil, err
-	}
-
-	return token, nil
+func (c *Client) generate(ctx *negotiate.ClientContext, msg []byte) ([]byte, error) {
+	return ctx.MakeSignature(msg, 0, 0)
 }
 
-// Verify verifies the TSIG MAC based on the established context.
-// It is called with the bytes of the DNS message, and the TSIG record
-// containing the algorithm, MAC, and name which is the negotiated TKEY
-// for this context.
-// It returns any error that occurred.
-func (c *Client) Verify(stripped []byte, t *dns.TSIG) error {
-	if dns.CanonicalName(t.Algorithm) != tsig.GSS {
-		return dns.ErrKeyAlg
-	}
-
-	c.m.RLock()
-	defer c.m.RUnlock()
-
-	ctx, ok := c.ctx[t.Hdr.Name]
-	if !ok {
-		return dns.ErrSecret
-	}
-
-	token, err := hex.DecodeString(t.MAC)
-	if err != nil {
-		return err
-	}
-
-	if _, err = ctx.VerifySignature(stripped, token, 0); err != nil {
-		return err
-	}
+func (c *Client) verify(ctx *negotiate.ClientContext, stripped, mac []byte) error {
+	_, err := ctx.VerifySignature(stripped, mac, 0)
 
-	return nil
+	return err
 }
 
 func (c *Client) negotiateContext(host string, creds *sspi.Credentials) (string, time.Time, error) {