48
edits
Changes
Jump to navigation
Jump to search
Line 1:
Line 1: − #REDIRECT [[IR Services#IR Service "ir:USER"]]+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
no edit summary
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)