@cashdev 11 December 2019

«Is it an SLP transaction?» using Python Here is a quick and crude way to check if an transaction is likely an SLP transaction. It can be a transaction that sends a SLP token, creates one, mints more or whatever. We don't check that its valid, or if what it's doing is valid, we just want to flag it as potentially SLP. Here's how you do it: # OPRETURN [PUSH 4] S L P 0x00 SLP_PREFIX = bytearray(b"\x6a\x04\x53\x4c\x50\x00") def has_slp_output(outputs): for o in outputs: if o.scriptPubKey.startswith(SLP_PREFIX): return True return False This uses the python library python-bitcoincash. To install, run `pip install bitcoincash` (replace `pip` with `pip3` if you're on Debian/Ubuntu to use Python 3) https://pypi.org/project/bitcoincash/ What magic is this? SLP token transaction all have an *OP_RETURN* output. This output also starts with the 4 byte prefix *SLP0*. So all we need to do is check for this byte prefix. `0x6a` - OP_RETURN `0x04` - Push 4 bytes `0x53` - ASCII character 'S' `0x4c` - ASCII character 'L' `0x50` - ASCII character 'P' `0x00` - 0 A simple test Here are two transaction in raw hex, how you parse them and call the above function on them. You can fetch raw transactions from *bitcoind* with the RPC command `getrawtransaction txid`. NOT_SLP = '010000000122836eee490f711e6a32727aeabaf3ea55d577ce66d2dfc3c9f15448e03358990000000064412f09efc8ace5405bec70257f4d749ebab32dbf296158a46195d611c1b4a49f2159789446171fd191ae1c3e3b5151cca79c021d7c0f5d5e3add2fbc9748dc2fe8412103920fbdeb0667bae173b0ab297869206e4bc23faaa527d6c910bb3f6f66a72cfbfeffffff019a8b9600000000001976a91481b193ccc14242267f1b8a07294d7cb12c91356d88ac8d510900' SLP_TX = "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" from bitcoincash.core import CTransaction, x tx = CTransaction.deserialize(x(SLP_TX)) assert(has_slp_output(tx.vout)) tx = CTransaction.deserialize(x(NOT_SLP)) assert(not has_slp_output(tx.vout)) [sponsors]