M10 FX remittance for Solana

This project provides a sample Solana implementation of a delayed FX remittance smart contract. It allows the exchange of tokens of currency A to be swapped for tokens of currency B when certain conditions are met, i.e. the exchange rate reaches an upper or lower limit, or the validity period for the swap has been reached. This allows users to optimize for a more opportune FX rate instead of settling for the current market rate.

The program provides a Solana smart contract implementation, i.e. a program, & a CLI tool to interact with the FX program. Liquidity is provided as a static exchange rate for demo purposes, but can be provided by an external exchange rate oracle, e.g. ChainLink.

Pre-requisites

• Install the required platform dependencies:

  • sudo apt-get install libssl-dev libudev-dev pkg-config zlib1g-dev llvm clang cmake make libprotobuf-dev protobuf-compiler

• Install the Solana CLI tools

  • e.g. sh -c "$(curl -sSfL https://release.solana.com/v1.10.31/install)"

• Install the Rust toolchain

  • e.g. curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh

• Install the SPL token CLI

  • e.g. cargo install spl-token-cli

• Note: optionally a Dockerfile is provided for a ready to build and use development environment (give it plenty of resources!)

  • docker build . --tag m10-fx-solana:latest -f ./Dockerfile
  • docker run --name m10-fx-solana --rm -it -v "$(pwd)":/m10-fx-solana m10-fx-solana
  • Use screen to run test-ledger in the background after creating your key screen -dmS test-ledger solana-test-validator

Build & Deploy

CLI

use the cargo tool to build the CLI:

cargo build --release --bin m10-fx-solana-cli

or run it directly using cargo run, e.g.

cargo run --release --bin m10-fx-solana-cli

Program

Set the cluster to a config of your choice, e.g. for local development:

solana config set -ul

Create a new keypair (~account) for the test-ledger:

solana-keygen new -o ~/.config/solana/id.json

Launch a local Solana test cluster in the directory of your choice using: In a seperate window, launch a local Solana test cluster in the directory of your choice using:

solana-test-validator

Fund the test-ledger account:

solana airdrop 10

Using the cargo tool, run

cargo build-bpf

which provides the instructions for deployment after compiling successfully, e.g.

export FX_PROGRAM_KEY=$(solana address -k ./keys/program.key)
solana airdrop 10 $FX_PROGRAM_KEY # To fund the program
solana program deploy ./target/deploy/m10_fx_solana.so -k ./keys/program.key

Initialization

We'll need to set up a few identities before we interact with the program. We'll need to set up two tokens: SAR & IDR, representing the Saudi Riyal & the Indonesian Rupiah respectively. For that we'll need to create 2 Mint accounts in the spl-token program. For each, we'll need to create a liquidity provider account & provide them with a sufficient supply of tokens. The code in the program is set up to use the keys in the keys directory.

Export our keys for later use

export IDR_MINT=$(solana address -k ./keys/idr_mint.key) && \
export IDR_LIQUIDITY=$(solana address -k ./keys/idr_liquidity.key) && \
export SAR_MINT=$(solana address -k ./keys/sar_mint.key) && \
export SAR_LIQUIDITY=$(solana address -k ./keys/sar_liquidity.key) && \
export ALICE=$(solana address -k ./keys/alice.key) && \
export BOB=$(solana address -k ./keys/bob.key)

# Generate IDR mint (ignore the "Refusing to overwrite" warnings, those are expected for idempotent behavior)
solana-keygen new --outfile ./keys/idr_mint.key --no-bip39-passphrase
spl-token create-token --decimals 2 ./keys/idr_mint.key --mint-authority ./keys/idr_mint.key
solana airdrop 10 $IDR_MINT

# Generate IDR liquidity holding
solana-keygen new --outfile ./keys/idr_liquidity.key --no-bip39-passphrase
spl-token -v create-account --owner ./keys/idr_liquidity.key $IDR_MINT -- ./keys/idr_liquidity.key
spl-token mint --mint-authority ./keys/idr_mint.key $IDR_MINT 1000000 $IDR_LIQUIDITY
solana airdrop 10 $IDR_LIQUIDITY

# Generate SAR mint
solana-keygen new --outfile ./keys/sar_mint.key --no-bip39-passphrase
spl-token create-token --decimals 2 ./keys/sar_mint.key --mint-authority ./keys/sar_mint.key
solana airdrop 10 $SAR_MINT

# Generate SAR liquidity holding
solana-keygen new --outfile ./keys/sar_liquidity.key --no-bip39-passphrase
spl-token -v create-account --owner ./keys/sar_liquidity.key $SAR_MINT -- ./keys/sar_liquidity.key
spl-token mint --mint-authority ./keys/sar_mint.key $SAR_MINT 10000000 $SAR_LIQUIDITY
solana airdrop 10 $SAR_LIQUIDITY

After that we'll create our two customers, Alice & Bob, who will be attempting to exchange between IDR & SAR respectively.

# Create an IDR account for Alice
solana-keygen new --outfile ./keys/alice.key --no-bip39-passphrase
spl-token -v create-account --owner ./keys/alice.key $IDR_MINT -- ./keys/alice.key
spl-token mint --mint-authority ./keys/idr_mint.key $IDR_MINT 5000000 $ALICE
solana airdrop 1 $ALICE

# Create a SAR account for Bob
solana-keygen new --outfile ./keys/bob.key --no-bip39-passphrase
spl-token -v create-account --owner ./keys/bob.key $SAR_MINT -- ./keys/bob.key
solana airdrop 1 $BOB

Executing FX swaps

Using the CLI a user can interact with the fx program. In order for Alice to Initiate the contract, she'll need to invoke the following command:

cargo run --release --bin m10-fx-solana-cli -- initiate \
  --signer ./keys/alice.key \
  --amount 100000 \
  --from $ALICE \
  --to $BOB \
  --margin 0.10 \
  --payer ~/.config/solana/id.json \
  --valid-for 30

This proposes an FX swap of 1000.00 SAR from Alice's account to the equivalent in IDR for Bob. The swap will take place when either an optimal rate is found or the validity period, defined by valid-for, has been exceeded. In this case, the swap will run for a maximum of 60 seconds unless the FX rate moves more than 10% from the current rate, i.e. decreases by or increases by 10%. The payer argument defines which account will pay the required sol fees for the transactions. The signer argument indicates Alice invokes the contract.

cargo run --release --bin m10-fx-solana-cli -- initiate --signer ./keys/alice.key -a 100000 -f $ALICE -t $BOB --margin 0.10 --payer ~/.config/solana/id.json --valid-for 30
     Running `target/debug/m10-fx-solana-cli initiate --signer ./keys/alice.key -a 100000 -f C7UhfEFxFDUYYai4aEvvUm2Ubx6hqVzX2J6P1jPQjL6Z -t AYPFrwvbJ1RQHnn1xMyHYDqJLghmppEcYFwAo6V6oCig --margin 0.10 --payer ~/.config/solana/id.json --valid-for 30`
Initiate { signer: "./keys/alice.key", payer: "~/.config/solana/id.json", from: C7UhfEFxFDUYYai4aEvvUm2Ubx6hqVzX2J6P1jPQjL6Z, to: AYPFrwvbJ1RQHnn1xMyHYDqJLghmppEcYFwAo6V6oCig, amount: 100000, margin: 0.10, valid_for: Some(30) }
Current exchange rate 0.0002509788173878124686276478
Set margin to 0.10. Limits: [0.0002258809356490312217648830, 0.0002760766991265937154904126]
Created account 5VroT7EPENrznkptphxfH2K3T5tLqH7nDsHNBKTbSzKp with 1000 funds
Created FX account 6QCSzK56UKzDxruzgU81XzPEf4PpVMTTrp7bsfCRBPhp

The initiate command has created an FX account (6QCSzK56UKzDxruzgU81XzPEf4PpVMTTrp7bsfCRBPhp) which will allow executing the contract it contains. The contract can be pinged by using the execute command using the SAR liquidity provider key.

cargo run --release --bin m10-fx-solana-cli -- execute \
  --fx-account 6QCSzK56UKzDxruzgU81XzPEf4PpVMTTrp7bsfCRBPhp \
  --liquidity ./keys/sar_liquidity.key \
  --payer ~/.config/solana/id.json

This tries to execute the fx program with data stored in the fx-account. The address of the account is printed at the end of the initiate command above. It needs permission to provide liquidity for the SAR token using the liquidity argument. Again, the payer argument defines which account will pay the required sol fees for the transactions.

cargo run --release --bin m10-fx-solana-cli -- execute --fx-account 6QCSzK56UKzDxruzgU81XzPEf4PpVMTTrp7bsfCRBPhp --liquidity ./keys/sar_liquidity.key --payer ~/.config/solana/id.json
  Running `target/debug/m10-fx-solana-cli execute --fx-account 6QCSzK56UKzDxruzgU81XzPEf4PpVMTTrp7bsfCRBPhp --liquidity ./keys/sar_liquidity.key --payer ~/.config/solana/id.json`
Execute { fx_account: 6QCSzK56UKzDxruzgU81XzPEf4PpVMTTrp7bsfCRBPhp, liquidity: "./keys/sar_liquidity.key", payer: "~/.config/solana/id.json" }
Successfully executed FX swap

In case of a longer duration contract, the execute command will continue polling every 15 seconds until the program has completed.

References

• Solana
• Programming on Solana - An Introduction
• ChainLink