esp32-tcp-boot | TCP socket bootloader for the ESP32 over WPA2-Enterprise

Once connected to the network, the bootloader opens a TCP socket to the computer and port provided during the configuration step, sends the MAC address of the ESP, and waits for the OTA image. The TCP server could deliver different images to devices depending on their MAC address, using knowledge of their individual hardware configuration (the example does not do this yet). Due to RAM constraints, the image is flashed unconditionally while a running SHA1 checksum is calculated. Once flashing is complete, the SHA1 sum observed during programming is compared with the value provided by the TCP server. If this sum matches, the OTAData partition is updated, marking the delivered OTA application bootable. If this hash fails, the OTA partition is not marked bootable, and the update process restarts. As the TCP channel is supposedly reliable, the SHA1 sum during the update process is expected to fail very infrequently and is simply a confidence boosting measure. If a less reliable channel was to be used for communication, it makes some sense to break up the OTA image into chunks small enough to fit into the ESP's RAM and compute the hashes before flashing. Again, the TCP stack should insulate us from a lot of that, so a single checksum is used for simplicity.