Fix nRF firmware minor findings and config-read chunk cap (MJ-14)#4
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Fix nRF firmware minor findings and config-read chunk cap (MJ-14)#4balloob wants to merge 1 commit into
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- MJ-14: derive the config-read chunk cap from MAX_CONFIG_SIZE instead of a magic 10, so a full config is always readable and the cap stays correct if the constants change. - Add the total_size sanity check (0 / > MAX_CONFIG_SIZE) NACK on the chunked-config first packet, mirroring the Silabs firmware. - Size enc_buf to MAX_ENCRYPTED_PACKET_SIZE (542) instead of 512 to remove a latent overflow if a max-size encrypted response is ever produced. - Document why the direct-write END refresh-mode byte is not honored on nRF (driver exposes only a single full-refresh entry point). Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_012g2e8mr132vcizx92WsgiR
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Batch of small nRF firmware fixes, matching the Silabs firmware where a companion behavior exists.
MAX_CONFIG_SIZE.handle_read_configcapped reads at a magic10chunks.MAX_CONFIG_SIZEis 512, so the old cap (~958 B usable) already covered a full config, but the magic number was fragile. The cap is now computed asceil(MAX_CONFIG_SIZE / (MAX_RESPONSE_DATA_SIZE - 6)), guaranteeing a full config is always readable and staying correct if either constant changes. The client already loops until it hastotalbytes.total_sizesanity check. The chunked-config first packet now NACKs an invalidtotal_size(== 0or> MAX_CONFIG_SIZE), mirroring the Silabs firmware (opendisplay_pipe.c). Previously a bogus huge size just never completed (bounded elsewhere, non-exploitable, but now fails fast).enc_bufsized toMAX_ENCRYPTED_PACKET_SIZE(542).send_response'senc_bufwas[512]while the declared max encrypted packet is 542, a latent overflow if a max-size encrypted response were ever produced. Now sized to the constant.payload[0]==1 -> fast). The nRF EPD driver exposes only a single full-refresh entry point (epd_driver_t.refreshtakes no mode argument;SSD16xx_Refresh/UC81xx_Refreshalways do a full refresh with no fast LUT), so this can't be honored without a driver API change. Added a clear comment rather than faking it.Note: MJ-14 also needs the companion config-read cap raise in the Silabs and Arduino firmwares.
Build: no
arm-none-eabi-gcc/SDK available in this environment; changes host syntax-checked and the cap/size arithmetic verified (enc_buf 542 B; derived cap covers 512 B).🤖 Generated with Claude Code
https://claude.ai/code/session_012g2e8mr132vcizx92WsgiR