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Undo revision 12391 by Socram8888 (talk)
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−This service was added with [[2.0.0-2]]. It employs a custom packet format with obfuscation and error detection.+
−= Command set =
−When sending data, SendIrnop is used when the size is <=0xFC, otherwise SendIrnopLarge is used.
−
−{| class="wikitable" border="1"
−|-
−! Command Header
−! Available since system version
−! Description
−|-
−| 0x00010182
−| [[2.0.0-2]]
−| InitializeIrnop
−|-
−| 0x00020000
−| [[2.0.0-2]]
−| FinalizeIrnop
−|-
−| 0x00030000
−| [[2.0.0-2]]
−| ClearReceiveBuffer
−|-
−| 0x00040000
−| [[2.0.0-2]]
−| ClearSendBuffer
−|-
−| 0x0005....
−| [[2.0.0-2]]
−| WaitConnection
−|-
−| 0x00060040
−| [[2.0.0-2]]
−| RequireConnection (u8 input)
−|-
−| 0x0007....
−| [[2.0.0-2]]
−| AutoConnection
−|-
−| 0x0008....
−| [[2.0.0-2]]
−| AnyConnection
−|-
−| 0x00090000
−| [[2.0.0-2]]
−| Disconnect
−|-
−| 0x000A0000
−| [[2.0.0-2]]
−| GetReceiveEvent (writes event handle to cmdreply[3])
−|-
−| 0x000B0000
−| [[2.0.0-2]]
−| GetSendEvent (writes event handle to cmdreply[3])
−|-
−| 0x000C0000
−| [[2.0.0-2]]
−| GetConnectionStatusEvent (writes event handle to cmdreply[3])
−|-
−| 0x000D0042
−| [[2.0.0-2]]
−| SendIrnop (u32 size, ((Size<<14) <nowiki>|</nowiki> 2), inbufptr)
−|-
−| 0x000E0042
−| [[2.0.0-2]]
−| SendIrnopLarge (u32 size, ((Size<<8) <nowiki>|</nowiki> 10), inbufptr)
−|-
−| 0x000F....
−| [[2.0.0-2]]
−| ReceiveIrnop
−|-
−| 0x0010....
−| [[2.0.0-2]]
−| ReceiveIrnopLarge
−|-
−| 0x0011....
−| [[2.0.0-2]]
−| GetLatestReceiveErrorResult
−|-
−| 0x0012....
−| [[2.0.0-2]]
−| GetLatestSendErrorResult
−|-
−| 0x0013....
−| [[2.0.0-2]]
−| GetConnectionStatus
−|-
−| 0x0014....
−| [[2.0.0-2]]
−| GetTryingToConnectStatus
−|-
−| 0x0015....
−| [[2.0.0-2]]
−| GetReceiveSizeFreeAndUsed
−|-
−| 0x0016....
−| [[2.0.0-2]]
−| GetSendSizeFreeAndUsed
−|-
−| 0x0017....
−| [[2.2.0-X]]
−| GetConnectionRole
−|-
−| 0x00180182
−| [[2.2.0-X]]
−| InitializeIrnopShared (u32, u32, u32, u32, u32, u8, 0, handle)
−|-
−| 0x00190040
−| [[2.2.0-X]]
−| ReleaseReceivedData (32bit_value input)
−|-
−| 0x001A0040
−| [[2.2.0-X]]
−| SetOwnMachineId (u8 input)
−|}
−
−= Protocol description =
−Packets are sent using IrDA-SIR, with a 8N1 encoding (eight data bits, one stop bit, without parity). Each one is formed by a 2-byte header, a varint with the payload size, an obfuscated payload, and trailing error detection byte.
−
−== Packet header ==
−The packet header is fixed and consists in a synchronization byte (0xA5), followed by a unused (possibly RFU) zero byte. After these two hardcoded bytes, there's a varint representing the payload size, which may use one byte or two, depending on the how big the payload is.
−
−* For payloads with less than 64 bytes, the third byte represents the payload size.
−* For packets with up to 16383 bytes, the size is split in two bytes, with the third byte being the upper 6 bits of the payload size, OR'd with 0x40, and the fourth being the lower eight bits of the payload size
−
−For packets with less than 64 bytes:
−{| class="wikitable" border="1"
−! Sync
−! RFU
−! Size
−|-
−| 0xA5
−| 0x00
−| size
−|}
−
−For packets with up to 16383 bytes:
−{| class="wikitable" border="1"
−! Sync
−! RFU
−! Size (1)
−! Size (2)
−|-
−| 0xA5
−| 0x00
−| (size >> 8) <nowiki>|</nowiki> 0x40
−| size & 0xFF
−|}
−
−In C:
− <nowiki>uint8_t * setPacketHeader(uint8_t * buffer, size_t payloadSize) {
− assert(payloadSize < 16384);
−
− buffer[0] = 0xA5;
− buffer[1] = 0x00;
−
− if (payloadSize < 64) {
− buffer[2] = payloadSize;
− buffer += 3;
− } else {
− buffer[2] = 0x40 | (payloadSize >> 8);
− buffer[3] = payloadSize;
− buffer += 4;
− }
−
− return buffer;
−}</nowiki>
−
−== Payload ==
−The payload is obfuscated using a XOR-based encryption. In C:
− <nowiki>void payloadObfuscate(const void * voidplain, void * voidcipher, size_t size) {
− uint16_t * plain = (uint16_t *) voidplain;
− uint16_t * cipher = (uint16_t *) voidcipher;
− size_t halfCount = size / sizeof(uint16_t);
−
− uint16_t xorval = htobe16(0xE963);
− size_t i;
−
− for (i = 0; i < halfCount; i++) {
− xorval ^= plain[i];
− cipher[i] = xorval;
− }
−}
−
−void payloadDeobfuscate(const void * voidcipher, void * voidplain, size_t size) {
− uint16_t * cipher = (uint16_t *) voidcipher;
− uint16_t * plain = (uint16_t *) voidplain;
− size_t halfCount = size / sizeof(uint16_t);
−
− if (halfCount) {
− size_t i;
− for (i = halfCount - 1; i > 0; i--) {
− plain[i] = cipher[i] ^ cipher[i - 1];
− }
−
− plain[0] = cipher[0] ^ htobe16(0xE963);
− }
−}</nowiki>
−
−== Error detection ==
−The trailing error detection byte is calculated using [[CRC-8-CCITT]] <b>over the whole packet</b> (both the header and the payload)
#REDIRECT [[IR Services#IR Service "ir:USER"]]
−