All Questions

0
votes
2answers
26 views

Split State Storage Contract

This is a follow-up question of Split Contract Design Pitfall Background: I have split my logic into two contracts A and B. A keeps the state and not ETH. All state change functions are only allowed ...
0
votes
2answers
21 views

Cannot declare web3 object in JavaScript

When I try to declare a web3 object It's always undefined. I'm writting in JavaScript and using Infura as my provider for the ETH mainnet. I also tried with a local blockchain instead of Infura, but ...
0
votes
3answers
42 views

Auction contract question - Ether lock

I have an auction contract, where bidders bid with Ether then me (owner) select which offer is most suitable and thus this bidder is contract winner. Once the winner is selected, I send him data as a ...
2
votes
1answer
37 views

Target addresses in Kademlia

I'm currently trying to understand the Kademlia protocol implemented in Ethereum in order to discover other peers in the network. If I understand these lines correctly, a nodes uses both random ...
0
votes
1answer
19 views

Infura Request Limitations

Are there any official information about request limitations? I know for example that there is a limit for the amount of results in getLogs: https://infura.io/docs/ethereum/json-rpc/eth_getLogs ...
0
votes
1answer
18 views

Calling function of another contract in constructor not working anymore

I have a contract ElectionMaster that contains an array with all elections available in the network. When I create a new Election it calls a function addElection from ElectionMaster and registers ...
0
votes
0answers
13 views

Can't call contract function in Remix in Web3 provider mode, but it works in Javascript VM

A simple contract for addition, an error is reported when calling the function add in Web3 provider mode: "Gas estimation errored with the following message (see below). The transaction execution ...
0
votes
0answers
8 views

What is txpool equivalent in Parity?

I'm aware of txpool module in Geth where it able to show how many transactions in the pending and queue state. How to get the same result in Parity node? The parity_alltransactions looks like ...
0
votes
1answer
17 views

Problem understanding the owner assignment

Suppose I have 3 contracts, namely Owner, B and C: contract Owned { address public owner; constructor() public { owner = msg.sender; } modifier onlyOwner { require(...
0
votes
0answers
22 views

What are the specifications of Ethereum wallet smart contract? [closed]

I just want to know the must-have specs of an Ethereum ERC20 wallet contract. How can I make a wallet for normal users(Can just perform txns of their tokens.) and for high level(Can perform every ...
1
vote
1answer
13 views

Gasless Send: Keeping of Ether Wrongfully

I got following code from: A survey of Attacks from Ethereum Smart Contracts contract C { function pay(uint n, address d){ d.send(n); } } contract D1 { uint public count = 0; function()...
0
votes
1answer
25 views

How to call setter method of smart contract with web3 1.0.0

I don't know why but i'm not able to perform transaction with this code. please help me out i'm stuck. i just have to call setter method of my contract with some arguments. router.post("/set", async ...
0
votes
1answer
16 views

Contract Function calling storage contract not setting value correctly

so i have a storage Contract A which has the following mapping and function. mapping (address => mapping (bytes32 => uint8)) addressToQueryIDToStatus; // 0=no init, 1=init, 2=fail, 3=succeed, ...
0
votes
2answers
22 views

Why should I use an ERC-721 token to store data instead of a Smart Contract

Taking CryptoKitties as example, I'm sure it's possible to achieve the same concept of Crypto Collectable creating new kitties as Smart Contracts instead of using Tokens. Which would be the ...
0
votes
0answers
30 views

Why this error occurring when i running my dapp?

I create a dapp using Solidity,Web3Js,Javascript and Html with metamask i always getting this error when i am trying to submit my transition i am getting this error at c (inpage.js:1) at ...
0
votes
1answer
33 views

Sending a transaction without using MetaMask

I have designed a contract deployed on the Rinkeby with web3. I have also implemented a react app to interact with the blockchain. I want to use my application without metamask but I got this error ...
0
votes
1answer
29 views

How to recover/find metamask wallet file

So I had foolishly kept my metamask passphrase only on StickyNotes. This meant when my computer crashed, I had to reinstall all my programs, but all my files remained. For some reason my stickynotes ...
0
votes
2answers
28 views

use the caller of the wrapper function to call the inner function

Suppose, I have 2 contracts A and B: contract A{ function someMethod() public{ // Something happens here } } And contract B containing its instance and its wrapper function ...
0
votes
0answers
8 views

How to programmatically check the type of Ethereum node/backend that I'm connected to using Go?

I'm aware that I can do this using CURL like so: curl -H "Content-Type: application/json" -X POST --data '{"jsonrpc":"2.0","method":"web3_clientVersion","params":[],"id":67}' https://the-node-ip-...
0
votes
1answer
16 views

Problems syncing small private net consisting of 2 PC miner nodes and 3 Raspberry Pi nodes

I've read countless posts referencing some form of "Synchronisation failed, dropping peer err='retrieved hash chain is invalid'" and of the few that had solutions, none of them worked for me. I ...
1
vote
1answer
28 views

Remix error : Function declared as view but this (potentially) modifies state

i'm following a tutorial but now it is old, because was written more then 1 year ago, with 0.4.24 pragma and i also want upgrade this code. I got this error and i'm pretty sure to know why: view and ...
1
vote
1answer
49 views

Solidity Error:Running Out of Gas / selfdestruct problem

I've been going through 'Building Cryptocurrency and its ICO' by DappUniversity. I know many have questioned this issue and I've been through all the post but couldn't resolve it. The problem is self-...
0
votes
0answers
19 views

Web3js v0.20.7 - callback ls not a function

I'm facing issue of callback is not a function in web3js 0.20.7 when i call the method of sendRawTransaction to deploy smart contract with web3. When i used the same method just to call deployed ...
1
vote
0answers
28 views

Parity Ethereum Metamask

I have setup one test node on my machine and trying to connect with metamask and on node console i keep on receiving below message and unable to connect with node using metamask. 2019-06-14 14:48:32 ...
0
votes
0answers
12 views

Parity Ethereum - Public network

Want to create my own public network with pre-funded account, can any one point out the optimise, secure configuration for spanning node for Test and Main net ? To be more specific for Test Net I ...
0
votes
0answers
33 views

Truffle migration contract [duplicate]

Why do we have to deploy the migration solidity contract in truffle? Do we also have to deploy it during production? Why do we have to deploy it so many times and why can't we use a single large ...
0
votes
1answer
18 views

what does that 'No state variables' restriction in Libraries?

I read some about Libraries restriction that 'No state variables' but, some solidity code's Libraries have struct type. As far as I know that(may be wrong) struct type is 'storage' and 'state ...
2
votes
1answer
28 views

how does ERC1820 work

1820 keeps the record with mapping(address => mapping(bytes32 => address)) internal interfaces Which address is the actual contract which one is the interface? I assumed the first address is ...
0
votes
1answer
12 views

Why 'throw' is a problem in this Solidity code?

I found this code at the following site: Ethereum Griefing Wallets for (uint i=0; i<investors.length; i++) { if (investors[i].invested == min_investment) { // Refund, and check for failure. ...
0
votes
0answers
27 views

Timeout w/ Mocha on deploying a contract

Starting to build the following test suite for a contract. It deploys fine on Remix. I get the following error message. 1) "before each" hook for "deploys a contract": Error: Timeout of 20000ms ...
0
votes
2answers
28 views

Finding a better way to retrieve information about struct

I've run into a problem about getting information about the structs. The code is written below: pragma solidity ^0.4.23; contract Transport { address public manager; Batch[] public ...
0
votes
0answers
8 views

Get full name of keystore file after creating it

After creating a keystore by this code ks := keystore.NewKeyStore("./tmp", keystore.StandardScryptN, keystore.StandardScryptP) password := "secret" account, err := ks.NewAccount(password) ...
0
votes
1answer
21 views

Accessing MEW with Trezor One not working

I have been unable to access MEW using my Trezor One, when I click on Ether on the Trezor wallet page, it throws me into an unending loop back to the "How do you want to access your My Ether Wallet", ...
0
votes
0answers
27 views

Why am I getting the error "Expected pragma, import directive or contract/interface/library definition?

I have "pragma solidity ^0.5.9" at the start of the file yet I still get this error. Listing.sol:1:1: ParserError: Expected pragma, import directive or contract/interface/library definition. ...
1
vote
1answer
30 views

How to find the Bytecode of Ethereum Smart Contract by just it's address using JSON RPC

I am wondering that is there any way to find the byte-code of the Smart Contract which is published on a blockchain just by having only idea about it's contract address using JSON RPC running at 8545 ...
0
votes
0answers
21 views

How to use bip39 module in angular?

I am trying to create an ethereum wallet app using Ionic. I have tried to import bip39 node module directly in the angular project but it gives me error. Please help import { Injectable } from '@...
2
votes
2answers
49 views

Is there a maximum/optimum amount of ERC-721 that can be issued per contract?

Take a role playing game as example in which players are allowed to create any number of characters (each one defined by an ERC-721 token). What would be the consequences of having more than 10 ...
3
votes
1answer
25 views

Documenting Smart Contracts and Dapps - community standards and tools

Do you guys know of any kind of documentation standards that are widely used within the Ethereum community? Any kind of documentation tools will also be of great help. Thanks in advance.
2
votes
2answers
115 views

Is my ethereum solidity contract correct and safe

I am very new using Solidity to create Ethereum contracts and would like to know if the contract I have created is first correct and safe to use. What I am doing in this contract is allowing the user ...
4
votes
1answer
34 views

What is the meaning of Ethereum mainnet genesis block extradata value?

Mainnet genesis bloc (see https://etherscan.io/block/0) has 0x11bbe8db4e347b4e8c937c1c8370e4b5ed33adb3db69cbdb7a38e1e50b1b82fa as extraData value. It doesn't seem to convert to ascii and, as this ...
0
votes
1answer
31 views

How to get notification right after account has received eth by geth?

My server stores many accounts. How do i know when and what account has received eth or i have to check them manually one by one by looping many address to check the balance? account := common....
-2
votes
1answer
28 views

Ethereum address not find

Any one tell me how to know about which website generates this ETH address: 0x6fdd1c34b75b8638d3806adecbcbbc61ed4ed3b3
0
votes
0answers
37 views

Issue in truffle unbox zeppelinos/zepkit

As it is visible in the screenshot, I did not get a green check in the "setting up box". Anyone know why it is happening and will it cause any issue in the future?
0
votes
1answer
21 views

In node.js event is not fired

I am using web socket to get event. sending transaction works fine. but event is not fired. also I referred Web3 events not working but it does not work, too. I used eventemitter also. but it did ...
0
votes
1answer
19 views

Does the Wallet Griefing Attack still Exists?

I read about Wallet Griefing attack at the following link: [Ethereum Griefing Wallets][1] 'send' is checked but contract uses throw. The code is given below: for (uint i=0; i<investors.length; i+...
0
votes
1answer
43 views

what does external means ? how can i call the test2() inside my class

pragma solidity ^0.5.7; contract Test { function test() public view returns (uint){ return 10*10; } function test2() external view returns (uint){ ...
1
vote
1answer
25 views

How to test events that were sent by inner transaction / delegate call?

Usually, using truffle I can check for events like this: let { logs } = await myContract.doSomethingImportant( xxx ); // 1500 tokens are expected to get expectEvent.inLogs(logs, '...
1
vote
0answers
22 views

Example of Signedness Bug in Smart Contracts

I found an example of underflow bug at: Catching Vulnerable Smart Contracts Once and for All contract UnderflowAttack { ... function withdraw (uint amount) public { require(balances[msg.sender] -...
2
votes
1answer
27 views

Finding an element in array

pragma solidity ^0.4.17; contract Transport { address public manager; Car[] public carArray; Bike[] public bikeArray; struct Car { uint carId; address carOwner; } ...
1
vote
0answers
18 views

Why after managing to deploy contract to POA Ethereum blockchain I can't interact with it? [duplicate]

We are using a private ETH proof of authority blockchain. In order to deploy a contract I'm using 0 gas price and it deployed immediately. Then, Tried to deploy many types of contracts with ...

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