Questions tagged [calldata]
Questions about the "data" part in a transaction, which can be accessed by "msg.data". web3.eth.getTransaction calls this field "input".
2
votes
1answer
20 views
Understanding first evm word of reference types in assembly
Given the following function:
function getArrayItems(bytes calldata) external returns (
bytes4 _signature,
bytes32 _wutIsThis,
bytes32 _length,
bytes32 _firstItem
) {
assembly {
...
2
votes
1answer
42 views
can anyone help to explain calldataload
In the Solidity documentation, the definition of calldataload is:
calldataload(p) call data starting from position p (32 bytes)
But I am really confused by what is call data. Is the call data of ...
0
votes
0answers
26 views
Proxy contract DELEGATECALL to pass a DYNAMIC array to a function in the target contract
I'm trying to get a Proxy contract to correctly do a delegatecall to a function in another 'target' contract. The problem is, that I need to pass a dynamic array as the parameter to this function.
Q: ...
1
vote
3answers
60 views
Calldata with too many parameters
While reading https://solidity.readthedocs.io/en/v0.4.21/abi-spec.html#abi I was just thinking what happens when calldata contains more parameters/data than the function expects (I know first ...
1
vote
0answers
64 views
How to decode Tx data? Online tool?
Is there a fast way to decode the data returning from a Smart Contract call? I know there are github projects with JS libraries to decode this kind of data (such as https://github.com/ConsenSys/abi-...
0
votes
1answer
54 views
What is Calldata tag needed when a function has a string parameter?
I'm using:
pragma solidity ^0.5.0;
I have a function as below in my contract:
function test(string a) external{
a="apple";
}
An error shows up saying I need to add "calldata" to the parameter. ...
1
vote
1answer
83 views
Get the input data of a transaction with web3j
How can I retrieve transaction details (including the input data) from a txHash using Web3j?
I tried the following method:
public void buscarHhash(Web3j web3, String txHash) throws IOException {
...
1
vote
1answer
279 views
How to access string arguments from calldata in external functions? (0.5.X)
With the introduction of Solc 0.5.X , parameter memory locations for arrays (and strings/bytes) must be made explicit. For external functions, this memory location is required to be specified as ...
3
votes
1answer
394 views
calldata keyword as parameter in solidity v0.5.0 function?
What purpose does the "calldata" serve in this parameter _owners? Is it a new keyword?
function setup(address[] calldata _owners, uint256 _threshold, address to, bytes calldata data)
Taken from ...
1
vote
2answers
50 views
Thinking through from traditional DB to ETH
I am looking for a data structure kind of like this:
[
"data": {
"id": 0,
"hash" : "5feceb66ffc86f38d952786c6d696c79c2dbc239dd4e91b46729d73a27fb57e9",
"owner" : 0,
"status" : "...
2
votes
1answer
90 views
How does a contract's constructor work and load input values?
I set up the following contract:
pragma solidity ^0.4.25;
contract Simplest {
uint x;
constructor(bool _lucky) public {
if (_lucky == true) {
x = 7;
} else {
...
0
votes
1answer
132 views
Solidity: msg.data vs bytes
This is a simple contract that has a function input_data(bytes data) and a simple fallback function that passes msg.data to function input_data.
contract test_input_data{
address owner;
event ...
2
votes
1answer
156 views
Call function by using bytesData. (call.value()())
Assume I have two contracts:
contract A {
function test1() public view returns(bool) {
return false;
}
}
contract B {
function testCall(address addr, data) public view returns(...
0
votes
1answer
206 views
Web3j directly gets string from contract by eth_call
I just have a simple solidity contract:
pragma solidity ^0.4.19;
contract SampleContract {
string value;
function SampleContract() public {
value = "hello world";
}
...
1
vote
0answers
86 views
delegatecall for Smart Contract versioning
I've a state variable
address public current;
which stores the address of the latest updated contract. This value can be modified with a function.
Then, I've a function of this kind
function ...
2
votes
3answers
284 views
How does MetaMask's TRANSACTION DATA work? How to interact with smart contracts by only using MetaMask?
I have this source code
pragma solidity ^0.4.21;
// Relevant part of the CaptureTheEther contract.
contract CaptureTheEther {
mapping (address => bytes32) public nicknameOf;
function ...
0
votes
0answers
21 views
Collecting data sent to account/contract
What would be the best way to collect data that is sent to an account/contract. Each of the data will be a string of 128 bytes. Should I just leave it in the transactions and read and filter them out ...
3
votes
2answers
285 views
Solidity CALL and DELEGATECALL: messages and data format
I have some questions about Solidity CALL and DELEGATECALL. I have already read some related threads (link), but found no answers to my doubts.
1) Is there any difference in performing a CALL to a ...
2
votes
1answer
192 views
Assign metadata to a transaction
How can I append some (extra) data to a transaction that calls a contract method (with given parameters)? The transaction has only one 'data' field which is used to serialize the method call.
If I ...
1
vote
1answer
293 views
How to send data to smart contract?
I have the variable w1_temp, which i need to send to contract
I have the following code:
var W1Temp = require('w1temp')
var Web3 = require('web3')
var web3 = new Web3()
web3.setProvider(new web3....
2
votes
3answers
96 views
Can I send data to non-contract address?
Metamask allows to attach data to any transaction. What happens if I send some data with some ETH to existing non-contract address? Is that data recorded on the blockchain? Can I read it later?
1
vote
1answer
554 views
Contract call from a contract from a contract?
As I understand it, it is possible for a contract to call another contract by using
othercontractaddress.call(gas_amount).value(eth amount)(tx data).
Or in this case sender -> contract A -> ...
0
votes
0answers
31 views
Is there a Limit for payload [duplicate]
Is there a limit to the size of calldata/transaction payload allowed in evm other than the block gas limit?
5
votes
1answer
288 views
Making call with contract instance vs making call with hashed method ID
As I understand there are two main ways to call a function in another contract.
1.) Using the 4 byte methodID ----> address.call(bytes4(sha3('foo()'))
2.) Using the contract ABI ---> ...
0
votes
1answer
228 views
Update dapp after contract transaction is mined
I made a web app that interacts with a smart contract, using truffle unbox webpack. My contract has a variable called sum and 2 functions: one called answer that increments the sum variable after it ...
3
votes
1answer
2k views
Decode Etherscan.io Contract Input Data
Reading my input data on etherscan, I see each value as hex values. Which is fine to read the addresses. But I would like to read the amounts [1] && [3] as numbers.
Contract Method
Function: ...
6
votes
2answers
473 views
Is sending some datas in the data field safe?
An airdrop ask to send it 0ETH with 150000 GAS and some datas in DATA field.
Is it safe?
What could be the aim of this transaction?
Thanks.
1
vote
3answers
2k views
Decoding contract output of web3 eth call
I have written data to a contract using sendRawTransaction, and am trying to fetch it using web3.eth.call for the function :
function checkRecord(uint id, bytes email) constant returns (uint id2, ...
3
votes
2answers
2k views
What is “data” param of rawTx? How to send ETH by using web3
I want to send eth by using web3 on testnet. Source address is 0xbddf0bf3ac858d7fb8a2bdda55884d61779ba5a9. The destination is 0x8005ceb675d2ff8c989cc95354438b9fab568681.
I found the example on web3 ...
5
votes
4answers
2k views
How to decode input data from tx using python3?
I am trying to decode input data from token sale transactions. This is one of the transactions I am trying to parse 0xf7b7196ca9eab6e4fb6e7bce81aeb25a4edf04330e57b3c15bece9d260577e2b
Which has the ...
0
votes
1answer
1k views
Using Ethereum to buy Tezos
I would like to use my Ethereum to buy Tezos.
Does anyone know if Coinbase pass transaction data along with the transaction?
Thanks.
1
vote
1answer
345 views
how to retrieve function call address from deployed contract for usage with MetaMask send + transaction data?
I've deployed a contract into my testrpc network.
$ truffle deploy
Using network 'development'.
Running migration: 1_initial_migration.js
Deploying Migrations...
Migrations: ...
0
votes
1answer
83 views
Use accounts as datastore
I am rather new to Ethereum and I wonder if the following scenario is possible. I want/need to store some data encoded as a JWT in the blockchain and have it (publicly) accessible via an ID. Only the "...
5
votes
1answer
1k views
How to send a smart token transaction from one account to another account using JSON RPC interface
I would like to send amounts of a created token from one address to another.
I would like to use eth_sendTransaction:
eth_sendTransaction
Creates new message call transaction or a contract creation,...
3
votes
2answers
5k views
How do I “Add Data” to a send transaction in Solidity
In myetherwallet, there is an +Advanced: Add Data Section where I can add data to the transaction.
How can I add this same data in a transaction I make in Solidity?
2
votes
0answers
471 views
Call vs Delegate Call call data format
I'm using both call and delegatecall within an assembly block and i've noticed that when issuing a call I need to provide 4 bytes (sig) + any arguments, whereas for delegatecall I need to provide 4 ...
3
votes
1answer
288 views
How can I call arbitrary function with arbitrary parameters from Solidity?
I am working on a voting library that allows members of a voting-DAO-like organization to vote on arbitrary actions. Security considerations (I know, arbitrary code execution is evil...) and ...
1
vote
0answers
425 views
abstract way of calling internal function instead of `this.call(callData)`
In Solidity I can call an internal function (inside the same contract that is calling it) the "usual" way:
myFunc();
or I can call it via .call, as discussed here or here:
callData = bytes4(sha3("...
12
votes
2answers
5k views
What is msg.data?
Is msg.data equal to {from: addr1, data:something}?
How to handle the data 'something'?
when execution this code:
web3.eth.sendTransaction({from: ..., to: addressOfE, data: something});
how to ...
1
vote
1answer
117 views
What is preventing malicious miners stealing data to steal smart contract rewards?
The motivation for this question is roughly along the lines of a puzzle contract -- whoever submits the correct solution to the puzzle gets a reward from the contract.
I'm guessing that the 'thing' ...
2
votes
0answers
184 views
“No data is deployed on the contract address” [duplicate]
Following token tutorial on ethereum.org, get error message
No data is deployed on the contract address
Forgive me, but I am new to mist. How do I find the "MyAdvancedToken" in Mist?
2
votes
0answers
330 views
eth_sendTransaction for function with address type parameters
I'm interacting with my local private blockchain created using geth. I'm able to use eth_call, but now I have some problems with eth_sendTransaction.
The signature of the function is this:
function ...
3
votes
2answers
1k views
Generate contract data hex for 'confirm' function on eth multisig wallet
I have an account on a hardware wallet that is an owner of a standard multsig wallet contract. I want to be able to approve a transaction that is originated from a different wallet. If I have access ...
4
votes
1answer
771 views
How can I decode getData from a contract method call
I'm using myContractInstance.myMethod.getData() to be able to serialize a transaction:
// Get the call data, so you can call the contract through some other means
var myCallData = myContractInstance....
8
votes
2answers
703 views
Can msg.data be used as an identifier?
I'm looking at the multisig wallet implementation here and I see the usage of sha3(msg.data,block.number) being used as an identifier.
What exactly is inside the msg.data and why is it unique enough ...
3
votes
0answers
35 views
How to make sense of the “data” sent to execute a contract? [duplicate]
I'm trying to understand the technical details of Ethereum and one thing I can't find any info about is the data to be sent to a contract.
For example, I have a very simple coin flip betting ...
0
votes
0answers
76 views
Are there any libraries/tools for encoding input for data field of web3.eth.call method? [duplicate]
You can call contract functions using web3.eth.call method. Information on which function to call and what arguments to pass to this function is encoded according to the rules that can be found here. ...
3
votes
1answer
1k views
Can you help me parse this input data from a newProposal transaction from The DAO?
Every Ethereum transaction that represents a function call on a smart contract holds an input field with data that corresponds to the data sent through the interface of the function. For example, this ...
4
votes
1answer
1k views
Storing data in the blockchain inside a transaction
This question is related to this one and this one. I'm trying to store data in the blockchain inside the transaction data field:
The second question offers a solution using a contract but is it ...
1
vote
1answer
84 views
How do I retrieve the event data related to the creation and transfer of The DAO tokens?
How do I retrieve the data related to the creation and transfer of The DAO tokens?
This data will be useful to trace the movements in The DAO balances.
