git.iko.soy/bridge
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bridge/src/lib/tank.js
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1// /lib/tank: functions for funding transactions
3import retry from 'async-retry';
4import { toBN } from 'web3-utils';
5import { RETRY_OPTIONS, waitForTransactionConfirm } from './txn';
6import { WALLET_TYPES } from 'lib/constants';
7import { isRopsten } from './flags';
9const TANK_ADDRESS = '0x40f0A6db85f8D7A54fF3eA915b040dE8Cd4A0Eb5';
11//NOTE if accessing this in a localhost configuration fails with "CORS request
12// did not succeed", you might need to visit localhost:3001 or whatever
13// explicitly and tell your browser that's safe to access.
14// https://stackoverflow.com/a/53011185/1334324
15const port = isRopsten ? '3011' : '3001';
16const baseUrl = `https://gas-tank.urbit.org:${port}`;
18function sendRequest(where, what) {
19 return new Promise((resolve, reject) => {
20 fetch(baseUrl + where, {
21 method: 'POST',
22 cache: 'no-cache',
23 headers: {
24 'Content-Type': 'application/json',
25 },
26 body: JSON.stringify(what),
27 })
28 .then(response => {
29 if (response.ok) {
30 resolve(response.json());
31 } else {
32 reject(response);
33 }
34 })
35 .catch(reject);
36 });
39const remainingTransactions = point => {
40 if (typeof point === 'string') point = Number(point);
41 return sendRequest('/point', { point: point });
42};
44const fundTransactions = signedTxs => {
45 return sendRequest('/request', { txs: signedTxs });
46};
48// resolves when address has at least cost balance
49// returns true if gas tank was used, false otherwise
50// askForFunding: callback that takes (address, requiredBalance, currentBalance)
51// and tells the user to get that address the required balance
52// gotFunding: optional callback that stops telling the user to go get funding
53const ensureFundsFor = async (
54 web3,
55 point,
56 address,
57 walletType,
58 cost,
59 signedTxs,
60 askForFunding,
61 gotFunding
62) => {
63 if (typeof signedTxs !== 'object' || signedTxs.length === 0) {
64 throw new Error('tank: no transactions provided!');
65 }
67 const balance = toBN(await web3.eth.getBalance(address));
68 cost = toBN(cost);
70 if (balance.gte(cost)) {
71 console.log(
72 `tank: already have sufficient funds: ${address} proposed ` +
73 `transaction(s) that will cost ${cost.toString()}wei but it ` +
74 `already has ${balance.toString()}wei`
75 );
76 return false;
77 }
79 if (walletType === WALLET_TYPES.METAMASK) {
80 console.log('tank: disabling for metamask login');
82 return false;
83 }
84 try {
85 // TODO: if we can't always (easily) provide a point, and the
86 // fundTransactions call is gonna fail anyway, should we maybe
87 // just not bother doing this check in the first place?
88 if (point !== null) {
89 const fundsRemaining = await remainingTransactions(point);
90 if (fundsRemaining < signedTxs.length) {
91 throw new Error('tank: request invalid');
92 }
93 } else {
94 console.log('tank: no point provided. skipping remaining-funds check...');
95 }
97 const res = await fundTransactions(signedTxs);
98 if (!res.success) {
99 throw new Error(`tank: request rejected ${JSON.stringify(res)}`);
100 }
102 await waitForTransactionConfirm(web3, res.txHash);
104 const newBalance = toBN(await web3.eth.getBalance(address));
106 // sanity check
107 if (newBalance.lt(cost)) {
108 throw new Error(
109 `tank: transaction funded but the new balance of ` +
110 `${newBalance.toString()}wei is still less than ` +
111 `${cost.toString()}wei.`
112 );
113 }
115 console.log(
116 `tank: funds have confirmed: ${address} now has ` +
117 `${newBalance.toString()}wei, up from ${balance.toString()}wei`
118 );
119 return true;
120 } catch (error) {
121 console.error(error);
122 await waitForBalance(
123 web3,
124 address,
125 cost.toString(),
126 askForFunding,
127 gotFunding
128 );
129 }
131 return false;
132};
134// returns a promise that resolves when address has at least minBalance
135function waitForBalance(web3, address, minBalance, askForFunding, gotFunding) {
136 minBalance = toBN(minBalance);
137 return retry(async (bail, n) => {
138 const balance = toBN(await web3.eth.getBalance(address));
139 if (balance.gte(minBalance)) {
140 gotFunding && gotFunding();
141 return;
142 } else {
143 askForFunding(address, minBalance.toString(), balance);
144 throw new Error('retrying');
145 }
146 }, RETRY_OPTIONS);
149export {
150 TANK_ADDRESS,
151 remainingTransactions,
152 fundTransactions,
153 ensureFundsFor,
154};