Extract telnet functions into a separate header

telnet.h

@@ -0,0 +1,25 @@
+/* Handles details related to telnet protocol. */
+
+#define TELNET_MSG_SIZE_CHARMODE 9
+
+/**
+ * Creates a telnet protocol message that tells client to go into "character"
+ * mode. The passed data buffer must be big enough to hold the message payload
+ * with the size defined by TELNET_MSG_SIZE_CHARMODE.
+ * Operates directly on the passed data buffer.
+ */
+void telnet_message_set_character_mode(char *databuf);
+
+/**
+ * Handles special characters in the data buffer after receiving them from the
+ * client. Used to filter out the handshake commands of telnet protocol.
+ * Operates directly on the passed data buffer and modifies the payload length.
+ */
+void telnet_handle_client_read(char *databuf, int *datalen);
+
+/**
+ * Handles special characters in the data buffer before sending them to the
+ * client. Used to correctly echo the characters to the telnet client.
+ * Operates directly on the passed data buffer and modifies the payload length.
+ */
+void telnet_handle_client_write(char *databuf, int *datalen);