TSIG name must be presented in canonical form (#574)

* TSIG name must be presented in canonical form

Update the documentation to make clear that the zonename in the
TsigSecret map must be in canonical form.

* Reference RFC 4034 for canonical form

client.go

@@ -20,7 +20,7 @@ const tcpIdleTimeout time.Duration = 8 * time.Second
 type Conn struct {
 	net.Conn                         // a net.Conn holding the connection
 	UDPSize        uint16            // minimum receive buffer for UDP messages
-	TsigSecret     map[string]string // secret(s) for Tsig map[<zonename>]<base64 secret>, zonename must be fully qualified
+	TsigSecret     map[string]string // secret(s) for Tsig map[<zonename>]<base64 secret>, zonename must be in canonical form (lowercase, fqdn, see RFC 4034 Section 6.2)
 	rtt            time.Duration
 	t              time.Time
 	tsigRequestMAC string
@@ -39,7 +39,7 @@ type Client struct {
 	DialTimeout    time.Duration     // net.DialTimeout, defaults to 2 seconds, or net.Dialer.Timeout if expiring earlier - overridden by Timeout when that value is non-zero
 	ReadTimeout    time.Duration     // net.Conn.SetReadTimeout value for connections, defaults to 2 seconds - overridden by Timeout when that value is non-zero
 	WriteTimeout   time.Duration     // net.Conn.SetWriteTimeout value for connections, defaults to 2 seconds - overridden by Timeout when that value is non-zero
-	TsigSecret     map[string]string // secret(s) for Tsig map[<zonename>]<base64 secret>, zonename must be fully qualified
+	TsigSecret     map[string]string // secret(s) for Tsig map[<zonename>]<base64 secret>, zonename must be in canonical form (lowercase, fqdn, see RFC 4034 Section 6.2)
 	SingleInflight bool              // if true suppress multiple outstanding queries for the same Qname, Qtype and Qclass
 	group          singleflight
 }

server.go

@@ -285,7 +285,7 @@ type Server struct {
 	WriteTimeout time.Duration
 	// TCP idle timeout for multiple queries, if nil, defaults to 8 * time.Second (RFC 5966).
 	IdleTimeout func() time.Duration
-	// Secret(s) for Tsig map[<zonename>]<base64 secret>.
+	// Secret(s) for Tsig map[<zonename>]<base64 secret>. The zonename must be in canonical form (lowercase, fqdn, see RFC 4034 Section 6.2).
 	TsigSecret map[string]string
 	// Unsafe instructs the server to disregard any sanity checks and directly hand the message to
 	// the handler. It will specifically not check if the query has the QR bit not set.

xfr.go

@@ -17,7 +17,7 @@ type Transfer struct {
 	DialTimeout    time.Duration     // net.DialTimeout, defaults to 2 seconds
 	ReadTimeout    time.Duration     // net.Conn.SetReadTimeout value for connections, defaults to 2 seconds
 	WriteTimeout   time.Duration     // net.Conn.SetWriteTimeout value for connections, defaults to 2 seconds
-	TsigSecret     map[string]string // Secret(s) for Tsig map[<zonename>]<base64 secret>, zonename must be fully qualified
+	TsigSecret     map[string]string // Secret(s) for Tsig map[<zonename>]<base64 secret>, zonename must be in canonical form (lowercase, fqdn, see RFC 4034 Section 6.2)
 	tsigTimersOnly bool
 }