Adding exchange deposit receiver

near · Aug 20, 2020 · 322587d · 322587d
1 parent b0b851c
commit 322587d
Show file tree

Hide file tree

Showing 7 changed files with 97 additions and 1 deletion.
diff --git a/README.md b/README.md
@@ -5,6 +5,7 @@
 - [Whitelist Contract](./whitelist/)
 - [Staking Pool Factory](./staking-pool-factory/)
 - [Multisig contract](./multisig/)
+- [Exchange Deposit Receiver](./exchange-deposit-receiver)
 
 **Note**: observe the usage of the file `rust-toolchain` in the project root. This file contains toolchain information for nightly, while the `build.sh` scripts in respective contract subdirectories may override this with `cargo +stable`. Refer to the documentation on [the toolchain file and override precedence](https://github.com/rust-lang/rustup#the-toolchain-file). Keep in mind that the build scripts may use `stable` while `cargo test` may use nightly.
 
@@ -65,7 +66,7 @@ const result = account.signAndSendTransaction(
     contractName,
     [
         nearAPI.transactions.createAccount(),
-        nearAPI.transactions.transfer("100000000000000000000000000"), 
+        nearAPI.transactions.transfer("100000000000000000000000000"),
         nearAPI.transactions.deployContract(fs.readFileSync("res/lockup_contract.wasm")),
         nearAPI.transactions.functionCall("new", Buffer.from(JSON.stringify(newArgs)), 100000000000000, "0"),
     ]);

diff --git a/exchange-deposit-receiver/Cargo.lock b/exchange-deposit-receiver/Cargo.lock
diff --git a/exchange-deposit-receiver/Cargo.toml b/exchange-deposit-receiver/Cargo.toml
@@ -0,0 +1,17 @@
+[package]
+name = "exchange-deposit-receiver"
+version = "0.1.0"
+authors = ["Near Inc <hello@near.org>"]
+edition = "2018"
+publish = false
+
+[lib]
+crate-type = ["cdylib", "rlib"]
+
+[profile.release]
+codegen-units = 1
+# Tell `rustc` to optimize for small code size.
+opt-level = "s"
+lto = true
+debug = false
+panic = "abort"
diff --git a/exchange-deposit-receiver/README.md b/exchange-deposit-receiver/README.md
@@ -0,0 +1,54 @@
+# Exchange deposit receiver
+
+## Background
+
+Exchanges usually creates an new account for a user to deposit their tokens. On NEAR, the account can't be created
+without a deposit to cover the occupied storage. It cost tokens on exchange side to create such account before the user
+can deposit tokens. So if the user doesn't deposit tokens to the account, the exchange spent tokens on the creation of
+the account.
+
+To avoid creating the account before any tokens from the user are received, the exchanges can also receive tokens
+directly into their hot wallet, but every deposit has to be marked to be able to properly attribute it to the owner.
+It's usually done with an additional `memo` field in the transaction. NEAR doesn't support comments on the transfers.
+But NEAR does have function calls and the ability to attach tokens with the function call.
+
+## Overview
+
+The goal of this contract is to provide a contract endpoint to be able to deposit tokens with a memo.
+
+### The process is the following:
+- An exchange deploys this contract on their hot wallet account. The exchange also maintains the full access to this account by
+having a full access key on this account. It allows exchange to withdraw tokens from this account.
+- When a user wants to deposit tokens to their account on the exchange, the exchange generates a unique `<MEMO>` message for
+a user.
+- The user sends a specific transaction to the exchange's hot wallet account with a single action.
+This action should be supported by the wallets and the lockup contract.
+```rust
+FunctionCall {
+    method_name: "exchange_deposit",
+    args: b"<MEMO>",
+    gas: ...,
+    deposit: <DEPOSIT_AMOUNT>,
+}
+```
+- The transaction gets executed and the exchange's hot wallet account receives the `<DEPOSIT_AMOUNT>`.
+- Exchange monitors incoming transactions and sees that this deposit has been associated with the `<MEMO>`.
+- The exchange can now attribute `<DEPOSIT_AMOUNT>` for the user's account by mapping it with the received `<MEMO>`.
+
+## Interface
+
+```rust
+pub fn exchange_deposit();
+```
+
+## API examples
+
+Send `10` NEAR tokens to the exchange account `coin_exchange` with memo `USER_123` from user `token_owner`.
+
+Command:
+
+```bash
+near call coin_exchange exchange_deposit 'USER_123' --accountId=token_owner --amount=10
+```
+
+NOTE: This command temporarily doesn't work due to near-cli assumption about JSON input format. See https://github.com/near/near-cli/issues/503
diff --git a/exchange-deposit-receiver/build.sh b/exchange-deposit-receiver/build.sh
@@ -0,0 +1,5 @@
+#!/bin/bash
+set -e
+
+RUSTFLAGS='-C link-arg=-s' cargo +nightly build --target wasm32-unknown-unknown --release
+cp target/wasm32-unknown-unknown/release/exchange_deposit_receiver.wasm ./res/
diff --git a/exchange-deposit-receiver/res/exchange_deposit_receiver.wasm b/exchange-deposit-receiver/res/exchange_deposit_receiver.wasm
diff --git a/exchange-deposit-receiver/src/lib.rs b/exchange-deposit-receiver/src/lib.rs
@@ -0,0 +1,14 @@
+#![no_std]
+#![feature(core_intrinsics)]
+#![allow(non_snake_case)]
+
+#[panic_handler]
+#[no_mangle]
+pub fn on_panic(_info: &::core::panic::PanicInfo) -> ! {
+    unsafe {
+        ::core::intrinsics::abort();
+    }
+}
+
+#[no_mangle]
+pub fn exchange_deposit() {}