options: Add binary option

Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>

options/binary.go

@@ -0,0 +1,47 @@
+package options
+
+import "github.com/PatrickRudolph/telnet"
+
+// BINARY Telnet binary Option - https://tools.ietf.org/html/rfc857
+
+// BinaryTransmissionOption enables Binary transmission negotiation on a Server.
+func BinaryTransmissionOption(c *telnet.Connection) telnet.Negotiator {
+	return &BinaryHandler{client: false}
+}
+
+// BinaryHandler negotiates BINARY for a specific connection.
+type BinaryHandler struct {
+	client bool
+}
+
+// OptionCode returns with the code used to negotiate BINARY modes.
+func (e *BinaryHandler) OptionCode() byte {
+	return telnet.TeloptBINARY
+}
+
+// Offer is called when a new connection is initiated. It offers the handler
+// an opportunity to advertise or request an option.
+func (e *BinaryHandler) Offer(c *telnet.Connection) {
+	if !e.client {
+		c.Conn.Write([]byte{telnet.IAC, telnet.DO, e.OptionCode()})
+	}
+}
+
+// HandleDo is called when an IAC DO command is received for this option,
+// indicating the client is requesting the option to be enabled.
+func (e *BinaryHandler) HandleDo(c *telnet.Connection) {
+
+}
+
+// HandleWill is called when an IAC WILL command is received for this
+// option, indicating the client is willing to enable this option.
+func (e *BinaryHandler) HandleWill(c *telnet.Connection) {
+
+}
+
+// HandleSB is called when a subnegotiation command is received for this
+// option. body contains the bytes between `IAC SB <OptionCode>` and `IAC
+// SE`.
+func (e *BinaryHandler) HandleSB(c *telnet.Connection, body []byte) {
+
+}