From 15789b641dfbc2c5bda8834e3f6929aaf90a3f1e Mon Sep 17 00:00:00 2001 From: Andreas Oberritter Date: Thu, 1 Dec 2022 12:13:22 +0100 Subject: [PATCH 1/2] Change somfy_iohc to recognize more messages - Messages can be as short as 11 bytes. - Message length has 5 bits instead of 4. - Flags were assumed to be constant, causing two-way remotes not to get recognized. - The message type (command id) is not indicated by the 1st but the 9th byte. - Trailing bytes were not removed, leading to invalid length and failing CRC. - Sequence numbers and MAC are limited to authenticated one-way frames. This was briefly tested using both one- and two-way remotes. --- src/devices/somfy_iohc.c | 117 ++++++++++++++++++++++++++++++--------- 1 file changed, 91 insertions(+), 26 deletions(-) diff --git a/src/devices/somfy_iohc.c b/src/devices/somfy_iohc.c index d8792a492..be5f3a3d6 100644 --- a/src/devices/somfy_iohc.c +++ b/src/devices/somfy_iohc.c @@ -91,60 +91,123 @@ Example packets: #include "decoder.h" +struct iohc_msg { + /* Mandatory fields */ + /* Control byte 1 */ + unsigned end_flag : 1; + unsigned start_flag : 1; + unsigned protocol_mode : 1; + unsigned frame_length : 5; + /* Control byte 2 */ + unsigned use_beacon : 1; + unsigned is_routed : 1; + unsigned low_power_mode : 1; + unsigned protocol_version : 3; + /* Addresses */ + unsigned dst_addr : 24; + unsigned src_addr : 24; + /* Command ID */ + unsigned cmd_id : 8; + char data[31 * 2 + 1]; /* variable length, converted to hex string */ + unsigned crc : 16; + + /* optional fields */ + int seq_nr; + char mac[13]; +}; + static int somfy_iohc_decode(r_device *decoder, bitbuffer_t *bitbuffer) { uint8_t const preamble_pattern[] = {0x57, 0xfd, 0x99}; + struct iohc_msg msg = {0}; - uint8_t b[19 + 15]; // 19 byte + up 15 byte payload + uint8_t b[1 + 31 + 2]; // Length, payload, CRC if (bitbuffer->num_rows != 1) return DECODE_ABORT_EARLY; - unsigned offset = bitbuffer_search(bitbuffer, 0, 0, preamble_pattern, 24) + 24; - if (offset + 19 * 10 >= bitbuffer->bits_per_row[0]) + unsigned offset = bitbuffer_search(bitbuffer, 0, 0, preamble_pattern, 24); + if (offset == bitbuffer->bits_per_row[0]) + return DECODE_ABORT_EARLY; + + offset += 24; + + int num_bits = bitbuffer->bits_per_row[0] - offset; + if (num_bits <= 0) return DECODE_ABORT_EARLY; - unsigned num_bits = bitbuffer->bits_per_row[0] - offset; - num_bits = MIN(num_bits, sizeof (b) * 8); + if ((size_t)num_bits > sizeof b * 8) + num_bits = sizeof b * 8; int len = extract_bytes_uart(bitbuffer->bb[0], offset, num_bits, b); - if (len < 19) + if (len < 11) return DECODE_ABORT_LENGTH; - if ((b[0] & 0xf0) != 0xf0) - return DECODE_ABORT_EARLY; - - int msg_len = b[0] & 0xf; // should be 6 or 8 - if (len < 19 + msg_len) + msg.frame_length = b[0] & 0x1f; + if (len < msg.frame_length + 3) return DECODE_ABORT_LENGTH; + len = msg.frame_length + 3; + + msg.end_flag = (b[0] & 0x80) >> 7; + msg.start_flag = (b[0] & 0x40) >> 6; + msg.protocol_mode = (b[0] & 0x20) >> 5; + msg.use_beacon = (b[1] & 0x80) >> 7; + msg.is_routed = (b[1] & 0x40) >> 6; + msg.low_power_mode = (b[1] & 0x20) >> 5; + msg.protocol_version = b[1] & 0x03; + msg.dst_addr = (b[2] << 16) | (b[3] << 8) | b[4]; + msg.src_addr = (b[5] << 16) | (b[6] << 8) | b[7]; + msg.cmd_id = b[8]; + + unsigned int data_length = msg.frame_length - 8; + if (msg.protocol_mode == 0 || data_length < 8) { + bitrow_snprint(&b[9], data_length * 8, msg.data, sizeof msg.data); + } else { + data_length -= 8; + bitrow_snprint(&b[9], data_length * 8, msg.data, sizeof msg.data); + msg.seq_nr = (b[9 + data_length] << 8) | b[9 + data_length + 1]; + bitrow_snprint(&b[9 + data_length + 2], 6 * 8, msg.mac, sizeof msg.mac); + } + + msg.crc = (b[len - 2] << 8) | b[len - 1]; // calculate and verify checksum if (crc16lsb(b, len, 0x8408, 0x0000) != 0) // unreflected poly 0x1021 return DECODE_FAIL_MIC; - decoder_logf_bitrow(decoder, 2, __func__, b, len * 8, "offset %u, num_bits %u, len %d, msg_len %d", offset, num_bits, len, msg_len); - int msg_type = (b[0]); - int dst_id = ((unsigned)b[4] << 24) | (b[3] << 16) | (b[2] << 8) | (b[1]); // assume Little-Endian - int src_id = ((unsigned)b[8] << 24) | (b[7] << 16) | (b[6] << 8) | (b[5]); // assume Little-Endian - int counter = (b[len - 10] << 8) | (b[len - 9]); - char msg_str[15 * 2 + 1]; - bitrow_snprint(&b[9], msg_len * 8, msg_str, 15 * 2 + 1); - char mac_str[13]; - bitrow_snprint(&b[len - 8], 6 * 8, mac_str, 13); + decoder_logf_bitrow(decoder, 2, __func__, b, len * 8, "offset %u, num_bits %u, len %d, msg_len %d", offset, num_bits, len, msg.frame_length); /* clang-format off */ data_t *data = data_make( "model", "", DATA_STRING, "Somfy-IOHC", - "id", "", DATA_FORMAT, "%08x", DATA_INT, src_id, - "dst_id", "Dest ID", DATA_FORMAT, "%08x", DATA_INT, dst_id, - "msg_type", "Msg type", DATA_FORMAT, "%02x", DATA_INT, msg_type, - "msg", "Message", DATA_STRING, msg_str, - "counter", "Counter", DATA_INT, counter, - "mac", "MAC", DATA_STRING, mac_str, + "id", "Source", DATA_FORMAT, "%06x", DATA_INT, msg.src_addr, + "dst_id", "Target", DATA_FORMAT, "%06x", DATA_INT, msg.dst_addr, + "msg_type", "Command", DATA_FORMAT, "%02x", DATA_INT, msg.cmd_id, + "msg", "Message", DATA_STRING, msg.data, "mic", "Integrity", DATA_STRING, "CRC", + "mode", "Mode", DATA_STRING, msg.protocol_mode ? "One-way" : "Two-way", + "version", "Version", DATA_INT, msg.protocol_version, + NULL); + + if (msg.protocol_mode == 1) + data = data_append(data, + "counter", "Counter", DATA_INT, msg.seq_nr, + "mac", "MAC", DATA_STRING, msg.mac, NULL); /* clang-format on */ + if (decoder->verbose) { + data_t *flags = data_make( + "end", "End", DATA_INT, msg.end_flag, + "start", "Start", DATA_INT, msg.start_flag, + "mode", "Mode", DATA_INT, msg.protocol_mode, + "beacon", "Beacon", DATA_INT, msg.use_beacon, + "routed", "Routed", DATA_INT, msg.is_routed, + "lpm", "LPM", DATA_INT, msg.low_power_mode, + NULL); + data = data_append(data, "flags", "Flags", DATA_DATA, flags, NULL); + } + decoder_output_data(decoder, data); return 1; } @@ -158,6 +221,8 @@ static char *output_fields[] = { "counter", "mac", "mic", + "mode", + "version", NULL, }; From 8dfd7d5a9bf9aa19e7ea445b4489c92a4bf1ab0b Mon Sep 17 00:00:00 2001 From: Andreas Oberritter Date: Thu, 1 Dec 2022 14:23:17 +0100 Subject: [PATCH 2/2] Add back use of MIN in somfy_iohc_decode --- src/devices/somfy_iohc.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/src/devices/somfy_iohc.c b/src/devices/somfy_iohc.c index be5f3a3d6..5384a285a 100644 --- a/src/devices/somfy_iohc.c +++ b/src/devices/somfy_iohc.c @@ -136,8 +136,7 @@ static int somfy_iohc_decode(r_device *decoder, bitbuffer_t *bitbuffer) if (num_bits <= 0) return DECODE_ABORT_EARLY; - if ((size_t)num_bits > sizeof b * 8) - num_bits = sizeof b * 8; + num_bits = MIN((size_t)num_bits, sizeof (b) * 8); int len = extract_bytes_uart(bitbuffer->bb[0], offset, num_bits, b); if (len < 11)