propose.js

import lib from "https://esm.sh/xrpl-accountlib?bundle";
import bin from "https://esm.sh/ripple-binary-codec?bundle";
import { XrplClient } from "https://esm.sh/xrpl-client?bundle";

// Alice
const notary_account = '{{ notary_account }}';

// Bob
const proposer_secret = '{{ proposer_secret }}';
const proposer_account = '{{ proposer_account }}';
const proposer_keypair = lib.derive.familySeed(proposer_secret);

const client = new XrplClient('wss://hooks-testnet-v2.xrpl-labs.com');

const main = async () => {
    console.log('notary_account', notary_account);
    const proposed_tx = {
        TransactionType: 'Payment',
        Account: notary_account,
        Amount: '100',
        Destination: proposer_account,
        DestinationTag: '42',
        LastLedgerSequence: "4000000000", 
        // Fee: '1200000'
	Fee: '0',
	Sequence: 0
    };

    const inner_tx = bin.encode(proposed_tx);
    
    const { account_data } = await client.send({ command: 'account_info', 'account': proposer_account });
    if (!account_data) {
        console.log('Proposer account not found.');
        client.close();
        return;
    }

    console.log("sequence", account_data.Sequence);

    const tx = {
        TransactionType: 'Payment',
        Account: proposer_account,
        Amount: '1',
        Destination: notary_account,
        Fee: '12000000',
        Memos: [
            {
                Memo: {
                    MemoData: inner_tx,
                    MemoFormat: "unsigned/payload+1",
                    MemoType: "notary/proposed"
                }
            }
        ],
        Sequence: account_data.Sequence
    };

    hexlify_memos(tx);
    
    const {signedTransaction} = lib.sign(tx, proposer_keypair);
    const submit = await client.send({ command: 'submit', 'tx_blob': signedTransaction });
    console.log(submit);

    console.log('Shutting down...');
    client.close();
};

function hexlify_memos(x)
{
    if (!("Memos" in x))
        return;

    for (y in x["Memos"])
    {
        for (a in x["Memos"][y])
        {
            let Fields = ["MemoFormat", "MemoType", "MemoData"];
            for (z in Fields)
            {
                if (Fields[z] in x["Memos"][y][a])
                {
                    let u = x["Memos"][y][a][Fields[z]].toUpperCase()
                    if (u.match(/^[0-9A-F]+$/))
                    {
                        x["Memos"][y][a][Fields[z]] = u;
                        continue;
                    }

                    x["Memos"][y][a][Fields[z]] =
                            ""+Buffer.from(x["Memos"][y][a][Fields[z]]).toString('hex').toUpperCase();
                }
            }
        }
    }
}

main()

sign.js

import lib from "https://esm.sh/xrpl-accountlib?bundle";
import { XrplClient } from "https://esm.sh/xrpl-client?bundle";


// Alice
const notary_account = '{{ notary_account }}';

// Carol
const approver_secret = '{{ approver_secret }}';
const approver_account = '{{ approver_account }}';
const approver_keypair = lib.derive.familySeed(approver_secret);

const client = new XrplClient('wss://hooks-testnet-v2.xrpl-labs.com');

const main = async (proposal) => {
    console.log("proposal", proposal);
    try {
        const { account_data } = await client.send({ command: 'account_info', 'account': approver_account });
        if (!account_data) {
            console.log('Approver account not found.');
            client.close();
            return;
        }

        console.log("sequence", account_data.Sequence);
        
        const tx = {
            Account: approver_account,
            TransactionType: "Payment",
            Amount: "1",
            Destination: notary_account,
            Fee: "1000000",
            InvoiceID: proposal,
            Sequence: account_data.Sequence
        };

        const {signedTransaction} = lib.sign(tx, approver_keypair);

        const submit = await client.send({ command: 'submit', 'tx_blob': signedTransaction });
        console.log(submit);
    } catch (err) {
        console.error(err)
    }

    console.log('Shutting down...');
    client.close();
};

main("{{InvoiceID}}");

starter.c

/**
 * This hook just accepts any transaction coming through it
 */
 
#include "hookapi.h"

int64_t cbak(uint32_t reserved) { 
    return 0;
}

int64_t hook(uint32_t reserved ) {

    TRACESTR("Accept.c: Called.");
    accept (0,0,0); 

    _g(1,1);   // every hook needs to import guard function and use it at least once
    // unreachable
    return 0;
}