Transfer filter contract

EOS.IO has a method to check incoming transfers. If the memo of a transaction destined for this contract does not satisfy certain conditions, this contract would cancel the transaction. Currently set conditions are:

• Memo has to be exactly 8 symbols long;
• Contain only digits;

You can add different asserts in ontransfer action to modify these conditions.

Only transfers where this contract is the receiver are currently being filtered.

Build (on CDT over 1.3.0 needed)

eosiocpp -o transferfilter.wast transferfilter.cpp

Deploy

cleos set code <your-account-name> transferfilter.wast

Test

Without memo

$ cleos transfer eosio <your-account-name> "10.0000 SYS"
Error 3050003: eosio_assert_message assertion failure

With non digit

$ cleos transfer eosio <your-account-name> "10.0000 SYS" "1234567a"
Error 3050003: eosio_assert_message assertion failure

Valid

$ cleos transfer eosio <your-account-name> "10.0000 SYS" "00345670"
executed transaction: 747ceb78a0359ffd426df96d3ce4c844bfe7402e1634638a14ebc2d91c676a91  136 bytes  607 us
#   eosio.token <= eosio.token::transfer        {"from":"eosio","to":"<your-account-name>","quantity":"10.0000 SYS","memo":"00345670"}
#         eosio <= eosio.token::transfer        {"from":"eosio","to":"<your-account-name>","quantity":"10.0000 SYS","memo":"00345670"}
#      <your-account-name> <= eosio.token::transfer        {"from":"eosio","to":"<your-account-name>","quantity":"10.0000 SYS","memo":"00345670"}
warning: transaction executed locally, but may not be confirmed by the network yet    ]