Working TFTP server based OTA updates

Tested with 16MBit flash configuration, two rboot update slots.

Closes #10

extras/rboot-ota/ota-tftp.h

@@ -0,0 +1,33 @@
+#ifndef _OTA_TFTP_H
+#define _OTA_TFTP_H
+/* TFTP Server OTA Support
+ *
+ * To use, call ota_tftp_init_server() which will start the TFTP server task
+ * and keep it running until a valid image is sent.
+ *
+ * The server expects to see a valid image sent with filename "filename.bin"
+ * and will switch "slots" and reboot if a valid image is received.
+ *
+ * Note that the server will allow you to flash an "OTA" update that doesn't
+ * support OTA itself, and possibly brick the esp requiring serial upload.
+ *
+ * Example client comment:
+ * tftp -m octet ESP_IP -c put firmware/myprogram.bin firmware.bin
+ *
+ * TFTP protocol implemented as per RFC1350:
+ * https://tools.ietf.org/html/rfc1350
+ *
+ * IMPORTANT: TFTP is not a secure protocol.
+ * Only allow TFTP OTA updates on trusted networks.
+ *
+ */
+
+/* Start a FreeRTOS task to wait to receive an OTA update from a TFTP client.
+ *
+ * listen_port is the UDP port number to receive TFTP connections on (default TFTP port is 69)
+ */
+void ota_tftp_init_server(int listen_port);
+
+#define TFTP_PORT 69
+
+#endif