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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) #4

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21 changes: 19 additions & 2 deletions EPD/EPD_service.c
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Original file line number Diff line number Diff line change
Expand Up @@ -115,7 +115,7 @@ static uint32_t send_response(ble_epd_t* p_epd, uint8_t* response, uint16_t len)
}

if (isAuthenticated()) {
static uint8_t enc_buf[512];
static uint8_t enc_buf[MAX_ENCRYPTED_PACKET_SIZE];
uint16_t enc_len = 0;
uint8_t nonce[16];
uint8_t tag[12];
Expand Down Expand Up @@ -160,7 +160,13 @@ static void handle_read_config(ble_epd_t* p_epd) {
uint32_t remaining = configLen;
uint32_t offset = 0;
uint16_t chunkNumber = 0;
const uint16_t maxChunks = 10;
// Cap the number of read chunks so a full MAX_CONFIG_SIZE config is always
// readable. The worst-case usable payload per chunk is
// (MAX_RESPONSE_DATA_SIZE - 6) bytes: a 4-byte header plus, on chunk 0, a
// 2-byte total-length prefix. Deriving the cap from MAX_CONFIG_SIZE keeps it
// correct if either constant changes.
const uint16_t maxChunks =
(MAX_CONFIG_SIZE + (MAX_RESPONSE_DATA_SIZE - 6) - 1) / (MAX_RESPONSE_DATA_SIZE - 6);

while (remaining > 0 && chunkNumber < maxChunks) {
uint16_t responseLen = 0;
Expand Down Expand Up @@ -218,6 +224,12 @@ static void handle_write_config(ble_epd_t* p_epd, uint8_t* data, uint16_t len) {
chunkedWriteState.receivedChunks = 0;
if (len >= CONFIG_CHUNK_SIZE_WITH_PREFIX) {
chunkedWriteState.totalSize = data[0] | (data[1] << 8);
if (chunkedWriteState.totalSize == 0 || chunkedWriteState.totalSize > MAX_CONFIG_SIZE) {
chunkedWriteState.active = false;
uint8_t errorResponse[] = {0xFF, RESP_CONFIG_WRITE, 0x00, 0x00};
(void)send_response(p_epd, errorResponse, sizeof(errorResponse));
return;
}
chunkedWriteState.expectedChunks = (chunkedWriteState.totalSize + CONFIG_CHUNK_SIZE - 1) / CONFIG_CHUNK_SIZE;
uint16_t chunkDataSize = ((len - 2) < CONFIG_CHUNK_SIZE) ? (len - 2) : CONFIG_CHUNK_SIZE;
memcpy(chunkedWriteState.buffer, data + 2, chunkDataSize);
Expand Down Expand Up @@ -512,6 +524,11 @@ static void handle_direct_write_end(ble_epd_t* p_epd, uint8_t* data, uint16_t le
}
uint8_t ackResponse[] = {0x00, RESP_DIRECT_WRITE_END_ACK};
(void)send_response(p_epd, ackResponse, sizeof(ackResponse));
// NOTE: Silabs honors the END refresh-mode byte (payload[0]==1 -> fast).
// The nRF EPD driver only exposes a single full-refresh entry point
// (epd_driver_t.refresh takes no mode argument; SSD16xx_Refresh/UC81xx_Refresh
// always do a full refresh with no fast LUT), so the refresh-mode byte cannot
// be honored here without a driver API change. Always full refresh.
if (p_epd->epd->ic == DRV_IC_UC8176 || p_epd->epd->ic == DRV_IC_UC8179) {
EPD_WriteCmd(UC81xx_PTOUT);
}
Expand Down