initial commit

.dockerignore

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+db
+.env
+docker-compose.yml
+.git
+.ipynb_checkpoints

.gitignore

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+db
+.env
+docker-compose.yml
+.ipynb_checkpoints

Dockerfile

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+FROM python:3.9-alpine
+
+RUN apk update && apk upgrade
+# GCC.
+RUN apk add --no-cache --virtual .build-deps gcc musl-dev
+
+RUN python -m pip install --upgrade pip
+COPY requirements.txt .
+RUN python -m pip install -r requirements.txt
+
+# Remove gcc.
+RUN apk del .build-deps
+# Remove cache.
+RUN python -m pip cache purge
+
+WORKDIR /faucet
+
+COPY bridge-faucet.py .
+
+ENTRYPOINT python bridge-faucet.py

README.md

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+OmniBridge faucet service
+====
+
+This service is monitoring transfers executed through the OmniBridge on the xDai chain and reward the tokens recipients with small amount of xdai.
+
+## Run by docker CLI
+
+1. Prepare `.env` file with the following (at least) variables definitons:
+
+   ```bash
+   FAUCET_PRIVKEY=cafe...cafe
+   JSON_DB_DIR=/db
+   INITIAL_START_BLOCK=123
+   ```
+
+   See below with the variables explanation.
+
+2. Create the directory where the faucet service will store its data.
+
+   ```bash
+   mkdir ./db
+   ```
+
+3. Run the service 
+
+   ```bash
+   docker run -ti --rm -v $(pwd)/db:/db --env-file .env omnibridge/bridge-faucet:latest 
+   ```
+
+   _Note:_ the source mount point after the key `-v` is the directory created on the step 2. The destination mount point is the directory specified in the variable `JSON_DB_DIR`.
+
+## Run by docker-compose
+
+1. Create the directory where the faucet service will store its data.
+
+   ```bash
+   mkdir ./db
+   ```
+
+2. Initialize the `docker-compose.yml` file based on `docker-compose.yml.example`. Set proper values for the following variables (at least) there: `FAUCET_PRIVKEY`, `JSON_DB_DIR` and `INITIAL_START_BLOCK`.
+
+   Make sure that the source mount point in the `volumes` section is the directory created on the step 1.
+
+   See below with the variables explanation.
+
+3. Run the service 
+
+   ```bash
+   docker-compose up -d
+   ```
+
+## Faucet configuration 
+
+The following environment variables may be used to configure the faucet behavior:
+
+1. `XDAI_RPC` -- JSON RPC endpoint the faucet uses to monitor OB events and get data. **Default:** `https://xdai.poanetwork.dev`.
+
+2. `BSC_OB` -- an address of BSC-xDai OB mediator on the xDai side. **Default:** `0x59447362798334d3485c64D1e4870Fde2DDC0d75`.
+
+3. `ETH_OB` -- an address of ETH-xDai OB mediator on the xDai side. **Default:** `0xf6A78083ca3e2a662D6dd1703c939c8aCE2e268d`.
+
+4. `FAUCET_PRIVKEY` -- a private key of an account holding xdai to reward. **No default value!**.
+
+5. `GAS_PRICE` -- the gas price (in gwei) the faucet uses for reward transactions. **Default:** `1`.
+
+6. `GAS_LIMIT` -- the gas limit the faucet uses for reward transactions. **Default:** `30000`.
+
+7. `REWARD` -- amount of xdai used as reward. **Default:** `0.005`.
+
+8. `POLLING_INTERVAL` -- amount of time (in seconds) between two subsequent cycles to discover OB transfers and send rewards. **Default:** `60`.
+
+9. `INITIAL_START_BLOCK` -- a block the first faucet's attempt to discover OB transfers starts from. **No default value!**.
+
+10. `FINALIZATION_INTERVAL` -- a number of blocks starting from the chain head to consider the chain as finalized. **Default:** `12`.
+
+11. `JSON_DB_DIR` -- a directory where the faucet service keeps its data. **No default value!**.
+
+12. `JSON_START_BLOCK` -- a name of JSON file where the last observed block is stored. **Default:** `faucet_start_block.json`.
+
+13. `JSON_CONTRACTS` -- a name of JSON file where addresses of recipient-contracts are stored. **Default:** `xdai-contracts.json`.

bridge-faucet.py

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+#!/usr/bin/env python3
+
+from json import load, dump
+from web3 import Web3, HTTPProvider
+from eth_account import Account
+from time import sleep
+from os import getenv
+from dotenv import load_dotenv
+from logging import basicConfig, info, INFO
+
+basicConfig(level=INFO)
+
+STOP_FILE = 'stop.tmp'
+
+dotenv_read = False
+
+while True: 
+    XDAI_RPC = getenv('XDAI_RPC', 'https://xdai.poanetwork.dev')
+
+    BSC_OB = getenv('BSC_OB', '0x59447362798334d3485c64D1e4870Fde2DDC0d75')
+    ETH_OB = getenv('ETH_OB', '0xf6A78083ca3e2a662D6dd1703c939c8aCE2e268d')
+
+    FAUCET_PRIVKEY = getenv('FAUCET_PRIVKEY', None)
+
+    GAS_PRICE = int(getenv('GAS_PRICE', 1))
+    GAS_LIMIT = int(getenv('GAS_LIMIT', 30000))
+    REWARD = float(getenv('REWARD', 0.005))
+    POLLING_INTERVAL = getenv('POLLING_INTERVAL', 60)
+
+    #INITIAL_START_BLOCK = 16173518
+    INITIAL_START_BLOCK = int(getenv('INITIAL_START_BLOCK', 16190379))
+    FINALIZATION_INTERVAL = int(getenv('FINALIZATION_INTERVAL', 12)) # blocks
+
+    JSON_DB_DIR = getenv('JSON_DB_DIR', '.')
+    JSON_START_BLOCK = getenv('JSON_START_BLOCK', 'faucet_start_block.json')
+    JSON_CONTRACTS = getenv('JSON_CONTRACTS', 'xdai-contracts.json')
+
+    if not FAUCET_PRIVKEY:
+        if dotenv_read:
+            break
+
+        info('Environment is not configured')
+        load_dotenv('./.env')
+        dotenv_read = True
+    else: 
+        break
+
+if not FAUCET_PRIVKEY:
+    raise BaseException("Faucet's privkey is not provided. Check the configuration")
+
+info(f'XDAI_RPC = {XDAI_RPC}')
+info(f'BSC_OB = {BSC_OB}')
+info(f'ETH_OB = {ETH_OB}')
+info(f'FAUCET_PRIVKEY = ...')
+info(f'GAS_PRICE = {GAS_PRICE}')
+info(f'GAS_LIMIT = {GAS_LIMIT}')
+info(f'REWARD = {REWARD}')
+info(f'POLLING_INTERVAL = {POLLING_INTERVAL}')
+info(f'INITIAL_START_BLOCK = {INITIAL_START_BLOCK}')
+info(f'FINALIZATION_INTERVAL = {FINALIZATION_INTERVAL}')
+info(f'JSON_DB_DIR = {JSON_DB_DIR}')
+info(f'JSON_START_BLOCK = {JSON_START_BLOCK}')
+info(f'JSON_CONTRACTS = {JSON_CONTRACTS}')
+
+# event
+# TokensBridged(address token, address recipient, uint256 value, bytes32 messageId)
+ABI = """
+[
+  {
+    "type":"event",
+    "name":"TokensBridged",
+    "inputs":[
+      {
+        "type":"address",
+        "name":"token",
+        "internalType":"address",
+        "indexed":true
+      },
+      {
+        "type":"address",
+        "name":"recipient",
+        "internalType":"address",
+        "indexed":true
+      },
+      {
+        "type":"uint256",
+        "name":"value",
+        "internalType":"uint256",
+        "indexed":false
+      },
+      {
+        "type":"bytes32",
+        "name":"messageId",
+        "internalType":"bytes32",
+        "indexed":true
+      }
+    ],
+    "anonymous":false
+  }
+]
+"""
+
+xdai_w3 = Web3(HTTPProvider(XDAI_RPC))
+bsc_ob = xdai_w3.eth.contract(abi = ABI, address = BSC_OB)
+eth_ob = xdai_w3.eth.contract(abi = ABI, address = ETH_OB)
+
+faucet = Account.privateKeyToAccount(FAUCET_PRIVKEY)
+
+try:
+    with open(f'{JSON_DB_DIR}/{JSON_START_BLOCK}') as f:
+      tmp = load(f)
+      start_block = int(tmp['start_block'])
+except IOError:
+    info("no start block stored previously")
+    start_block = INITIAL_START_BLOCK
+info(f'start block: {start_block}')
+
+while True:
+    try:
+        with open(f'{JSON_DB_DIR}/{STOP_FILE}') as f:
+            info("Stopping faucet")
+            break
+    except IOError:
+        pass
+
+    try:
+        last_block = xdai_w3.eth.getBlock('latest').number
+    except:
+        raise BaseException('Cannot get the latest block number')
+    info(f'current last block: {last_block}')
+    last_block = last_block - FINALIZATION_INTERVAL
+
+    filter = bsc_ob.events.TokensBridged.build_filter()
+    info(f'Looking for TokensBridged events on BSC-xDAI OB from {start_block} to {last_block}')
+    try:
+        bsc_logs = xdai_w3.eth.getLogs({'fromBlock': start_block, 
+                                        'toBlock': last_block, 
+                                        'address': filter.address, 
+                                        'topics': filter.topics})
+    except:
+        raise BaseException('Cannot get BSC-xDAI OB OB logs')
+    info(f'Found {len(bsc_logs)} TokensBridged events on BSC-xDAI OB')
+
+    filter = eth_ob.events.TokensBridged.build_filter()
+    info(f'Looking for TokensBridged events on ETH-xDAI OB from {start_block} to {last_block}')
+    try:
+        eth_logs = xdai_w3.eth.getLogs({'fromBlock': start_block, 
+                                        'toBlock': last_block, 
+                                        'address': filter.address, 
+                                        'topics': filter.topics})
+    except:
+        raise BaseException('Cannot get ETH-xDAI OB OB logs')
+    info(f'Found {len(eth_logs)} TokensBridged events on ETH-xDAI OB')
+
+    recipients = set()
+
+    for log in bsc_logs:
+        recipient = bsc_ob.events.TokensBridged().processLog(log).args.recipient
+        recipients.add(recipient)
+    info(f'Identified {len(recipients)} tokens recipients from BSC-xDAI OB events')
+
+    tmp = len(recipients)
+    for log in eth_logs:
+        recipient = eth_ob.events.TokensBridged().processLog(log).args.recipient
+        recipients.add(recipient)
+    info(f'Identified {len(recipients) - tmp} tokens recipients from ETH-xDAI OB events')
+
+    try:
+        with open(f'{JSON_DB_DIR}/{JSON_CONTRACTS}') as f:
+          contracts = load(f)
+    except IOError:
+        info("no contracts identified previously")
+        contracts = {}
+
+    endowing = []
+    for recipient in recipients:
+        if recipient in contracts:
+            continue
+        code = xdai_w3.eth.getCode(recipient)
+        if code != b'':
+            contracts[recipient] = True
+            continue
+        balance = xdai_w3.eth.getBalance(recipient)
+        if balance == 0:
+            info(f'{recipient} balance is zero')
+            endowing.append(recipient)
+    info(f'found {len(endowing)} accounts for reward')
+
+    with open(f'{JSON_DB_DIR}/{JSON_CONTRACTS}', 'w') as json_file:
+      dump(contracts, json_file)
+
+    balance_error = False
+
+    if len(endowing) > 0:
+        try:
+            faucet_balance = xdai_w3.eth.getBalance(faucet.address)
+        except:
+            raise BaseException("Cannot get faucet balance")
+        info(f'faucet balance: {faucet_balance}')
+
+        if faucet_balance > len(endowing) * GAS_LIMIT * Web3.toWei(GAS_PRICE, 'gwei'):
+            try:
+                nonce = xdai_w3.eth.getTransactionCount(faucet.address)
+            except:
+                raise BaseException("Cannot get transactions count of faucet's account")
+            info(f'starting nonce: {nonce}')
+            for recipient in endowing:
+                tx = {
+                    'nonce': nonce,
+                    'gas': GAS_LIMIT,
+                    'gasPrice': Web3.toWei(GAS_PRICE, 'gwei'),
+                    'data': b'Rewarded for OmniBridge transaction',
+                    'chainId': 100,
+                    'value': Web3.toWei(REWARD, 'ether'),
+                    'to': recipient,
+                }
+                rawtx = faucet.signTransaction(tx)
+                sent_tx_hash = xdai_w3.eth.sendRawTransaction(rawtx.rawTransaction)
+                info(f'{recipient} rewarded by {Web3.toHex(sent_tx_hash)}')
+                nonce += 1
+                sleep(0.1)
+        else:
+            info(f'not enough balance on the faucet {faucet.address}')
+            balance_error = True
+
+    if not balance_error:
+        start_block = last_block + 1
+        with open(f'{JSON_DB_DIR}/{JSON_START_BLOCK}', 'w') as json_file:
+            dump({'start_block': start_block}, json_file)
+
+    sleep(POLLING_INTERVAL)

docker-compose.yml.example

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+version: "3.9"
+
+services:
+  faucet:
+    image: omnibridge/bridge-faucet:latest
+    container_name: bridge-faucet
+    environment:
+        # faucet account's private key must be here (without 0x)
+        - FAUCET_PRIVKEY=cafe...cafe
+        - JSON_DB_DIR=/db
+        - INITIAL_START_BLOCK=123
+    volumes:
+        - ./db:/db
+    restart: unless-stopped
+    logging:
+        driver: "json-file"
+        options:
+            max-size: "100m"
+            max-file: "1"

requirements.txt

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+eth-account==0.5.4
+web3==5.17.0
+python-dotenv==0.17.1