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Add call builder and eth_call state overrides (#1340) 

* Add call builder and eth_call state overrides

* Fix <Caller as Future>::poll impl

* Move call overrides to ethers_provider::call_raw

* Add example for call_raw overrides

* Add support for contract call overrides

* Documentation and convenience impls for call_raw types

* Test for eth_call state overrides

* ci: install geth

Co-authored-by: Georgios Konstantopoulos <me@gakonst.com>
This commit is contained in:
Gio 2022-06-04 15:18:25 -06:00 committed by GitHub
parent 3b54f18e4e
commit a532eb4d29
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GPG Key ID: 4AEE18F83AFDEB23
7 changed files with 801 additions and 5 deletions
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10
.github/workflows/ci.yml vendored
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@ -177,6 +177,16 @@ jobs:
- name: Checkout sources
uses: actions/checkout@v2
- name: Install geth (for state overrides example)
run: |
mkdir -p "$HOME/bin"
wget -q https://gethstore.blob.core.windows.net/builds/geth-linux-amd64-1.9.23-8c2f2715.tar.gz
tar -xvf geth-linux-amd64-1.9.23-8c2f2715.tar.gz
mv geth-linux-amd64-1.9.23-8c2f2715/geth $HOME/bin/geth
chmod u+x "$HOME/bin/geth"
export PATH=$HOME/bin:$PATH
geth version
- name: Install Anvil
uses: foundry-rs/foundry-toolchain@v1
with:

38
ethers-contract/src/call.rs
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@ -9,9 +9,12 @@ use ethers_core::{
},
utils::id,
};
use ethers_providers::{Middleware, PendingTransaction, ProviderError};
use ethers_providers::{
call_raw::{CallBuilder, RawCall},
Middleware, PendingTransaction, ProviderError,
};
use std::{borrow::Cow, fmt::Debug, marker::PhantomData, sync::Arc};
use std::{borrow::Cow, fmt::Debug, future::Future, marker::PhantomData, sync::Arc};
use thiserror::Error as ThisError;
@ -169,6 +172,37 @@ where
Ok(data)
}
/// Returns an implementer of [`RawCall`] which can be `.await`d to query the blockchain via
/// `eth_call`, returning the deoded return data.
///
/// The returned call can also be used to override the input parameters to `eth_call`.
///
/// Note: this function _does not_ send a transaction from your account
pub fn call_raw(
&self,
) -> impl RawCall<'_> + Future<Output = Result<D, ContractError<M>>> + Debug {
let call = self.call_raw_bytes();
call.map(move |res: Result<Bytes, ProviderError>| {
let bytes = res.map_err(ContractError::ProviderError)?;
decode_function_data(&self.function, &bytes, false).map_err(From::from)
})
}
/// Returns a [`CallBuilder`] which can be `.await`d to query the blochcain via `eth_call`,
/// returning the raw bytes from the transaction.
///
/// The returned call can also be used to override the input parameters to `eth_call`.
///
/// Note: this function _does not_ send a transaction from your account
pub fn call_raw_bytes(&self) -> CallBuilder<'_, M::Provider> {
let call = self.client.provider().call_raw(&self.tx);
if let Some(block) = self.block {
call.block(block)
} else {
call
}
}
/// Signs and broadcasts the provided transaction
pub async fn send(&self) -> Result<PendingTransaction<'_, M::Provider>, ContractError<M>> {
self.client

26
ethers-contract/src/factory.rs
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@ -1,5 +1,4 @@
use crate::{Contract, ContractError};
use std::marker::PhantomData;
use ethers_core::{
abi::{Abi, Token, Tokenize},
@ -8,12 +7,15 @@ use ethers_core::{
TransactionReceipt, TransactionRequest, U256, U64,
},
};
use ethers_providers::Middleware;
use ethers_providers::{
call_raw::{CallBuilder, RawCall},
Middleware,
};
#[cfg(not(feature = "legacy"))]
use ethers_core::types::Eip1559TransactionRequest;
use std::sync::Arc;
use std::{marker::PhantomData, sync::Arc};
/// Helper which manages the deployment transaction of a smart contract.
///
@ -114,6 +116,15 @@ impl<M: Middleware, C: From<Contract<M>>> ContractDeployer<M, C> {
self.deployer.call().await
}
/// Returns a CallBuilder, which when awaited executes the deployment of this contract via
/// `eth_call`. This call resolves to the returned data which would have been stored at the
/// destination address had the deploy transaction been executed via `send()`.
///
/// Note: this function _does not_ send a transaction from your account
pub fn call_raw(&self) -> CallBuilder<'_, M::Provider> {
self.deployer.call_raw()
}
/// Broadcasts the contract deployment transaction and after waiting for it to
/// be sufficiently confirmed (default: 1), it returns a new instance of the contract type at
/// the deployed contract's address.
@ -203,6 +214,15 @@ impl<M: Middleware> Deployer<M> {
Ok(())
}
/// Returns a CallBuilder, which when awaited executes the deployment of this contract via
/// `eth_call`. This call resolves to the returned data which would have been stored at the
/// destination address had the deploy transaction been executed via `send()`.
///
/// Note: this function _does not_ send a transaction from your account
pub fn call_raw(&self) -> CallBuilder<'_, M::Provider> {
self.client.provider().call_raw(&self.tx).block(self.block.into())
}
/// Broadcasts the contract deployment transaction and after waiting for it to
/// be sufficiently confirmed (default: 1), it returns a [`Contract`](crate::Contract)
/// struct at the deployed contract's address.

620
ethers-providers/src/call_raw.rs Normal file
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@ -0,0 +1,620 @@
//! Overrides for the `eth_call` rpc method
use crate::{JsonRpcClient, PinBoxFut, Provider, ProviderError};
use ethers_core::{
types::{
transaction::eip2718::TypedTransaction, Address, BlockId, BlockNumber, Bytes, H256, U256,
U64,
},
utils,
};
use pin_project::pin_project;
use serde::{ser::SerializeTuple, Deserialize, Serialize};
use std::{
fmt,
future::Future,
pin::Pin,
task::{Context, Poll},
};
pub use spoof::{balance, code, nonce, state, storage};
/// Provides methods for overriding parameters to the `eth_call` rpc method
pub trait RawCall<'a> {
/// Sets the block number to execute against
fn block(self, id: BlockId) -> Self;
/// Sets the [state override set](https://geth.ethereum.org/docs/rpc/ns-eth#3-object---state-override-set).
/// Note that not all client implementations will support this as a parameter.
fn state(self, state: &'a spoof::State) -> Self;
/// Maps a closure `f` over the result of `.await`ing this call
fn map<F>(self, f: F) -> Map<Self, F>
where
Self: Sized,
{
Map::new(self, f)
}
}
/// A builder which implements [`RawCall`] methods for overriding `eth_call` parameters.
///
/// `CallBuilder` also implements [`std::future::Future`], so `.await`ing a `CallBuilder` will
/// resolve to the result of executing the `eth_call`.
#[must_use = "call_raw::CallBuilder does nothing unless you `.await` or poll it"]
pub enum CallBuilder<'a, P> {
/// The primary builder which exposes [`RawCall`] methods.
Build(Caller<'a, P>),
/// Used by the [`std::future::Future`] implementation. You are unlikely to encounter this
/// variant unless you are constructing your own [`RawCall`] wrapper type.
Wait(PinBoxFut<'a, Bytes>),
}
impl<P: fmt::Debug> fmt::Debug for CallBuilder<'_, P> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Self::Build(call) => f.debug_tuple("Build").field(call).finish(),
Self::Wait(_) => f.debug_tuple("Wait").field(&"< Future >").finish(),
}
}
}
impl<'a, P> CallBuilder<'a, P> {
pub fn new(provider: &'a Provider<P>, tx: &'a TypedTransaction) -> Self {
Self::Build(Caller::new(provider, tx))
}
/// Applies a closure `f` to a `CallBuilder::Build`. Does nothing for `CallBuilder::Wait`.
pub fn map_input<F>(self, f: F) -> Self
where
F: FnOnce(&mut Caller<'a, P>),
{
match self {
Self::Build(mut call) => {
f(&mut call);
Self::Build(call)
}
wait => wait,
}
}
/// Returns the inner `Caller` from a `CallBuilder::Build`. Panics if the `CallBuilder` future
/// has already been polled.
pub fn unwrap(self) -> Caller<'a, P> {
match self {
Self::Build(b) => b,
_ => panic!("CallBuilder::unwrap on a Wait value"),
}
}
}
impl<'a, P> RawCall<'a> for CallBuilder<'a, P> {
/// Sets the block number to execute against
fn block(self, id: BlockId) -> Self {
self.map_input(|mut call| call.input.block = Some(id))
}
/// Sets the [state override set](https://geth.ethereum.org/docs/rpc/ns-eth#3-object---state-override-set).
/// Note that not all client implementations will support this as a parameter.
fn state(self, state: &'a spoof::State) -> Self {
self.map_input(|mut call| call.input.state = Some(state))
}
}
impl<'a, P: JsonRpcClient> Future for CallBuilder<'a, P> {
type Output = Result<Bytes, ProviderError>;
fn poll(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Self::Output> {
let pin = self.get_mut();
loop {
match pin {
CallBuilder::Build(ref call) => {
let fut = Box::pin(call.execute());
*pin = CallBuilder::Wait(fut);
}
CallBuilder::Wait(ref mut fut) => return fut.as_mut().poll(cx),
}
}
}
}
/// Holds the inputs to the `eth_call` rpc method along with the rpc provider.
/// This type is constructed by [`CallBuilder::new`].
#[derive(Clone, Debug)]
pub struct Caller<'a, P> {
provider: &'a Provider<P>,
input: CallInput<'a>,
}
impl<'a, P> Caller<'a, P> {
pub fn new(provider: &'a Provider<P>, tx: &'a TypedTransaction) -> Self {
Self { provider, input: CallInput::new(tx) }
}
}
impl<'a, P: JsonRpcClient> Caller<'a, P> {
/// Executes an `eth_call` rpc request with the overriden parameters. Returns a future that
/// resolves to the result of the request.
fn execute(&self) -> impl Future<Output = Result<Bytes, ProviderError>> + 'a {
self.provider.request("eth_call", utils::serialize(&self.input))
}
}
/// The input parameters to the `eth_call` rpc method
#[derive(Clone, Debug, PartialEq, Eq)]
struct CallInput<'a> {
tx: &'a TypedTransaction,
block: Option<BlockId>,
state: Option<&'a spoof::State>,
}
impl<'a> CallInput<'a> {
fn new(tx: &'a TypedTransaction) -> Self {
Self { tx, block: None, state: None }
}
}
impl<'a> Serialize for CallInput<'a> {
fn serialize<S>(&self, serializer: S) -> std::result::Result<S::Ok, S::Error>
where
S: serde::ser::Serializer,
{
let len = 2 + self.state.is_some() as usize;
let mut tup = serializer.serialize_tuple(len)?;
tup.serialize_element(self.tx)?;
let block = self.block.unwrap_or_else(|| BlockNumber::Latest.into());
tup.serialize_element(&block)?;
if let Some(state) = self.state {
tup.serialize_element(state)?;
}
tup.end()
}
}
/// An implementer of [`RawCall`] that maps a function `f` over the output of the inner future.
///
/// This struct is created by the [`map`] method on [`RawCall`].
///
/// [`map`]: RawCall::map
#[must_use = "call_raw::Map does nothing unless you `.await` or poll it"]
#[derive(Clone)]
#[pin_project]
pub struct Map<T, F> {
#[pin]
inner: T,
f: F,
}
impl<T: fmt::Debug, F> fmt::Debug for Map<T, F> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("Map").field("inner", &self.inner).finish()
}
}
impl<T, F> Map<T, F> {
pub fn new(inner: T, f: F) -> Self {
Self { inner, f }
}
}
impl<'a, T, F> RawCall<'a> for Map<T, F>
where
T: RawCall<'a>,
{
/// Sets the block number to execute against
fn block(self, id: BlockId) -> Self {
Self { inner: self.inner.block(id), f: self.f }
}
/// Sets the [state override set](https://geth.ethereum.org/docs/rpc/ns-eth#3-object---state-override-set).
/// Note that not all client implementations will support this as a parameter.
fn state(self, state: &'a spoof::State) -> Self {
Self { inner: self.inner.state(state), f: self.f }
}
}
impl<T, F, Y> Future for Map<T, F>
where
T: Future,
F: FnMut(T::Output) -> Y,
{
type Output = Y;
fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
let pin = self.project();
let x = futures_util::ready!(pin.inner.poll(cx));
Poll::Ready((pin.f)(x))
}
}
/// Provides types and methods for constructing an `eth_call`
/// [state override set](https://geth.ethereum.org/docs/rpc/ns-eth#3-object---state-override-set)
pub mod spoof {
use super::*;
use std::collections::HashMap;
/// The state elements to override for a particular account.
#[derive(Clone, Debug, Default, PartialEq, Eq, Serialize, Deserialize)]
pub struct Account {
#[serde(skip_serializing_if = "Option::is_none")]
pub nonce: Option<U64>,
#[serde(skip_serializing_if = "Option::is_none")]
pub balance: Option<U256>,
#[serde(skip_serializing_if = "Option::is_none")]
pub code: Option<Bytes>,
#[serde(flatten, skip_serializing_if = "Option::is_none")]
pub storage: Option<Storage>,
}
impl Account {
/// Override the account nonce
pub fn nonce(&mut self, nonce: U64) -> &mut Self {
self.nonce = Some(nonce);
self
}
/// Override the account balance
pub fn balance(&mut self, bal: U256) -> &mut Self {
self.balance = Some(bal);
self
}
/// Override the code at the account
pub fn code(&mut self, code: Bytes) -> &mut Self {
self.code = Some(code);
self
}
/// Override the value of the account storage at the given storage `key`
pub fn store(&mut self, key: H256, val: H256) -> &mut Self {
self.storage.get_or_insert_with(Default::default).insert(key, val);
self
}
}
/// Wraps a map from storage slot to the overriden value.
///
/// Storage overrides can either replace the existing state of an account or they can be treated
/// as a diff on the existing state.
#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
pub enum Storage {
#[serde(rename = "stateDiff")]
Diff(HashMap<H256, H256>),
#[serde(rename = "state")]
Replace(HashMap<H256, H256>),
}
/// The default storage override is a diff on the existing state of the account.
impl Default for Storage {
fn default() -> Self {
Self::Diff(Default::default())
}
}
impl std::ops::Deref for Storage {
type Target = HashMap<H256, H256>;
fn deref(&self) -> &Self::Target {
match self {
Self::Diff(map) => map,
Self::Replace(map) => map,
}
}
}
impl std::ops::DerefMut for Storage {
fn deref_mut(&mut self) -> &mut Self::Target {
match self {
Self::Diff(map) => map,
Self::Replace(map) => map,
}
}
}
/// A wrapper type that holds a complete state override set.
#[derive(Clone, Debug, Default, PartialEq, Eq, Serialize, Deserialize)]
#[serde(transparent)]
pub struct State(#[serde(skip_serializing_if = "HashMap::is_empty")] HashMap<Address, Account>);
impl State {
/// Returns a mutable reference to the [`Account`] in the map.
pub fn account(&mut self, adr: Address) -> &mut Account {
self.0.entry(adr).or_default()
}
}
/// Returns an empty state override set.
///
/// # Example
/// ```no_run
/// # use ethers_core::{
/// # types::{Address, TransactionRequest, H256},
/// # utils::{parse_ether, Geth},
/// # };
/// # use ethers_providers::{Provider, Http, Middleware, call_raw::{spoof, RawCall}};
/// # use std::convert::TryFrom;
/// #
/// # #[tokio::main(flavor = "current_thread")]
/// # async fn main() -> Result<(), Box<dyn std::error::Error>> {
/// let geth = Geth::new().spawn();
/// let provider = Provider::<Http>::try_from(geth.endpoint()).unwrap();
///
/// let adr1: Address = "0x6fC21092DA55B392b045eD78F4732bff3C580e2c".parse().unwrap();
/// let adr2: Address = "0x295a70b2de5e3953354a6a8344e616ed314d7251".parse().unwrap();
/// let key = H256::from_low_u64_be(1);
/// let val = H256::from_low_u64_be(17);
///
/// let tx = TransactionRequest::default().to(adr2).from(adr1).into();
///
/// // override the storage at `adr2`
/// let mut state = spoof::state();
/// state.account(adr2).store(key, val);
///
/// // override the nonce at `adr1`
/// state.account(adr1).nonce(2.into());
///
/// provider.call_raw(&tx).state(&state).await.unwrap();
/// # Ok(())
/// # }
/// ```
pub fn state() -> State {
Default::default()
}
/// Returns a state override set with a single element setting the balance of the address.
///
/// # Example
/// ```no_run
/// # use ethers_core::{
/// # types::{Address, TransactionRequest, H256},
/// # utils::{parse_ether, Geth},
/// # };
/// # use ethers_providers::{Provider, Http, Middleware, call_raw::{RawCall, spoof}};
/// # use std::convert::TryFrom;
/// #
/// # #[tokio::main(flavor = "current_thread")]
/// # async fn main() -> Result<(), Box<dyn std::error::Error>> {
/// let geth = Geth::new().spawn();
/// let provider = Provider::<Http>::try_from(geth.endpoint()).unwrap();
///
/// let adr1: Address = "0x6fC21092DA55B392b045eD78F4732bff3C580e2c".parse()?;
/// let adr2: Address = "0x295a70b2de5e3953354a6a8344e616ed314d7251".parse()?;
/// let pay_amt = parse_ether(1u64)?;
///
/// // Not enough ether to pay for the transaction
/// let tx = TransactionRequest::pay(adr2, pay_amt).from(adr1).into();
///
/// // override the sender's balance for the call
/// let state = spoof::balance(adr1, pay_amt * 2);
/// provider.call_raw(&tx).state(&state).await?;
/// # Ok(())
/// # }
/// ```
pub fn balance(adr: Address, bal: U256) -> State {
let mut state = State::default();
state.account(adr).balance(bal);
state
}
/// Returns a state override set with a single element setting the nonce of the address.
///
/// # Example
/// ```no_run
/// # use ethers_core::{
/// # types::{Address, TransactionRequest, H256},
/// # utils::{parse_ether, Geth},
/// # };
/// # use ethers_providers::{Provider, Http, Middleware, call_raw::{RawCall, spoof}};
/// # use std::convert::TryFrom;
/// #
/// # #[tokio::main(flavor = "current_thread")]
/// # async fn main() -> Result<(), Box<dyn std::error::Error>> {
/// let geth = Geth::new().spawn();
/// let provider = Provider::<Http>::try_from(geth.endpoint()).unwrap();
///
/// let adr: Address = "0x6fC21092DA55B392b045eD78F4732bff3C580e2c".parse()?;
/// let pay_amt = parse_ether(1u64)?;
///
/// let tx = TransactionRequest::default().from(adr).into();
///
/// // override the sender's nonce for the call
/// let state = spoof::nonce(adr, 72.into());
/// provider.call_raw(&tx).state(&state).await?;
/// # Ok(())
/// # }
/// ```
pub fn nonce(adr: Address, nonce: U64) -> State {
let mut state = State::default();
state.account(adr).nonce(nonce);
state
}
/// Returns a state override set with a single element setting the code at the address.
///
/// # Example
/// ```no_run
/// # use ethers_core::{
/// # types::{Address, TransactionRequest, H256},
/// # utils::{parse_ether, Geth},
/// # };
/// # use ethers_providers::{Provider, Http, Middleware, call_raw::{RawCall, spoof}};
/// # use std::convert::TryFrom;
/// #
/// # #[tokio::main(flavor = "current_thread")]
/// # async fn main() -> Result<(), Box<dyn std::error::Error>> {
/// let geth = Geth::new().spawn();
/// let provider = Provider::<Http>::try_from(geth.endpoint()).unwrap();
///
/// let adr: Address = "0x6fC21092DA55B392b045eD78F4732bff3C580e2c".parse()?;
/// let pay_amt = parse_ether(1u64)?;
///
/// let tx = TransactionRequest::default().to(adr).into();
///
/// // override the code at the target address
/// let state = spoof::code(adr, "0x00".parse()?);
/// provider.call_raw(&tx).state(&state).await?;
/// # Ok(())
/// # }
/// ```
pub fn code(adr: Address, code: Bytes) -> State {
let mut state = State::default();
state.account(adr).code(code);
state
}
/// Returns a state override set with a single element setting the storage at the given address
/// and key.
///
/// # Example
/// ```no_run
/// # use ethers_core::{
/// # types::{Address, TransactionRequest, H256},
/// # utils::{parse_ether, Geth},
/// # };
/// # use ethers_providers::{Provider, Http, Middleware, call_raw::{RawCall, spoof}};
/// # use std::convert::TryFrom;
/// #
/// # #[tokio::main(flavor = "current_thread")]
/// # async fn main() -> Result<(), Box<dyn std::error::Error>> {
/// let geth = Geth::new().spawn();
/// let provider = Provider::<Http>::try_from(geth.endpoint()).unwrap();
///
/// let adr: Address = "0x6fC21092DA55B392b045eD78F4732bff3C580e2c".parse()?;
/// let key = H256::from_low_u64_be(1);
/// let val = H256::from_low_u64_be(17);
///
/// let tx = TransactionRequest::default().to(adr).into();
///
/// // override the storage slot `key` at `adr`
/// let state = spoof::storage(adr, key, val);
/// provider.call_raw(&tx).state(&state).await?;
/// # Ok(())
/// # }
/// ```
pub fn storage(adr: Address, key: H256, val: H256) -> State {
let mut state = State::default();
state.account(adr).store(key, val);
state
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::{Http, Middleware, Provider};
use ethers_core::{
types::TransactionRequest,
utils::{get_contract_address, keccak256, parse_ether, Anvil, Geth},
};
use std::convert::TryFrom;
// Deserializes eth_call parameters as owned data for testing serialization
#[derive(Debug, Deserialize)]
struct CallInputOwned(
TypedTransaction,
Option<BlockId>,
#[serde(default)] Option<spoof::State>,
);
impl<'a> From<&'a CallInputOwned> for CallInput<'a> {
fn from(src: &'a CallInputOwned) -> Self {
Self { tx: &src.0, block: src.1, state: src.2.as_ref() }
}
}
// Tests "roundtrip" serialization of calls: deserialize(serialize(call)) == call
fn test_encode<'a, P>(call: CallBuilder<'a, P>) {
let input = call.unwrap().input;
let ser = utils::serialize(&input).to_string();
let de: CallInputOwned = serde_json::from_str(&ser).unwrap();
let de = CallInput::from(&de);
assert_eq!(input.tx, de.tx);
assert_eq!(input.state, de.state);
let block = input.block.or_else(|| Some(BlockNumber::Latest.into()));
assert_eq!(block, de.block);
}
#[test]
fn test_serialize() {
let adr1: Address = "0x6fC21092DA55B392b045eD78F4732bff3C580e2c".parse().unwrap();
let adr2: Address = "0x295a70b2de5e3953354a6a8344e616ed314d7251".parse().unwrap();
let k1 = utils::keccak256("foo").into();
let v1 = H256::from_low_u64_be(534);
let k2 = utils::keccak256("bar").into();
let v2 = H256::from_low_u64_be(8675309);
let tx = TypedTransaction::default();
let (provider, _) = Provider::mocked();
let call = provider.call_raw(&tx);
test_encode(call);
let mut state = spoof::state();
state.account(adr1).nonce(1.into()).balance(2.into()).store(k1, v1).store(k2, v2);
let call = provider.call_raw(&tx).block(100.into()).state(&state);
test_encode(call);
let mut state = spoof::state();
state.account(adr1).nonce(1.into());
state.account(adr2).nonce(7.into());
let call = provider.call_raw(&tx).state(&state);
test_encode(call);
// State override with an empty acccount should be encoded as "0xab..": {}
let mut state = spoof::state();
state.account(adr1);
let call = provider.call_raw(&tx).state(&state);
test_encode(call);
}
#[tokio::test]
async fn test_state_overrides() {
let geth = Geth::new().spawn();
let provider = Provider::<Http>::try_from(geth.endpoint()).unwrap();
let adr1: Address = "0x6fC21092DA55B392b045eD78F4732bff3C580e2c".parse().unwrap();
let adr2: Address = "0x295a70b2de5e3953354a6a8344e616ed314d7251".parse().unwrap();
let pay_amt = parse_ether(1u64).unwrap();
// Not enough ether to pay for the transaction
let tx = TransactionRequest::pay(adr2, pay_amt).from(adr1).into();
// assert that overriding the sender's balance works
let state = spoof::balance(adr1, pay_amt * 2);
provider.call_raw(&tx).state(&state).await.expect("eth_call success");
// bytecode that returns the result of the SELFBALANCE opcode
const RETURN_BALANCE: &str = "0x4760005260206000f3";
let bytecode = RETURN_BALANCE.parse().unwrap();
let balance = 100.into();
let tx = TransactionRequest::default().to(adr2).into();
let mut state = spoof::state();
state.account(adr2).code(bytecode).balance(balance);
// assert that overriding the code and balance at adr2 works
let bytes = provider.call_raw(&tx).state(&state).await.unwrap();
assert_eq!(U256::from_big_endian(bytes.as_ref()), balance);
// bytecode that deploys a contract and returns the deployed address
const DEPLOY_CONTRACT: &str = "0x6000600052602060006000f060005260206000f3";
let bytecode = DEPLOY_CONTRACT.parse().unwrap();
let nonce = 17.into();
let mut state = spoof::state();
state.account(adr2).code(bytecode).nonce(nonce);
// assert that overriding nonce works (contract is deployed to expected address)
let bytes = provider.call_raw(&tx).state(&state).await.unwrap();
let deployed = Address::from_slice(&bytes.as_ref()[12..]);
assert_eq!(deployed, get_contract_address(adr2, nonce.as_u64()));
// bytecode that returns the value of storage slot 1
const RETURN_STORAGE: &str = "0x60015460005260206000f3";
let bytecode = RETURN_STORAGE.parse().unwrap();
let slot = H256::from_low_u64_be(1);
let val = keccak256("foo").into();
let mut state = spoof::state();
state.account(adr2).code(bytecode).store(slot, val);
// assert that overriding storage works
let bytes = provider.call_raw(&tx).state(&state).await.unwrap();
assert_eq!(H256::from_slice(bytes.as_ref()), val);
}
}

1
ethers-providers/src/lib.rs
View File

@ -28,6 +28,7 @@ pub use stream::{interval, FilterWatcher, TransactionStream, DEFAULT_POLL_INTERV
mod pubsub;
pub use pubsub::{PubsubClient, SubscriptionStream};
pub mod call_raw;
pub mod erc;
use async_trait::async_trait;

41
ethers-providers/src/provider.rs
View File

@ -1,4 +1,5 @@
use crate::{
call_raw::CallBuilder,
ens, erc, maybe,
pubsub::{PubsubClient, SubscriptionStream},
stream::{FilterWatcher, DEFAULT_POLL_INTERVAL},
@ -230,6 +231,46 @@ impl<P: JsonRpcClient> Provider<P> {
}
})
}
/// Analogous to [`Middleware::call`], but returns a [`CallBuilder`] that can either be
/// `.await`d or used to override the parameters sent to `eth_call`.
///
/// See the [`call_raw::spoof`] for functions to construct state override parameters.
///
/// Note: this method _does not_ send a transaction from your account
///
/// [`call_raw::spoof`]: crate::call_raw::spoof
///
/// # Example
/// ```no_run
/// # use ethers_core::{
/// # types::{Address, TransactionRequest, H256},
/// # utils::{parse_ether, Geth},
/// # };
/// # use ethers_providers::{Provider, Http, Middleware, call_raw::{RawCall, spoof}};
/// # use std::convert::TryFrom;
/// #
/// # #[tokio::main(flavor = "current_thread")]
/// # async fn main() -> Result<(), Box<dyn std::error::Error>> {
/// let geth = Geth::new().spawn();
/// let provider = Provider::<Http>::try_from(geth.endpoint()).unwrap();
///
/// let adr1: Address = "0x6fC21092DA55B392b045eD78F4732bff3C580e2c".parse()?;
/// let adr2: Address = "0x295a70b2de5e3953354a6a8344e616ed314d7251".parse()?;
/// let pay_amt = parse_ether(1u64)?;
///
/// // Not enough ether to pay for the transaction
/// let tx = TransactionRequest::pay(adr2, pay_amt).from(adr1).into();
///
/// // override the sender's balance for the call
/// let mut state = spoof::balance(adr1, pay_amt * 2);
/// provider.call_raw(&tx).state(&state).await?;
/// # Ok(())
/// # }
/// ```
pub fn call_raw<'a>(&'a self, tx: &'a TypedTransaction) -> CallBuilder<'a, P> {
CallBuilder::new(self, tx)
}
}
#[cfg(feature = "celo")]

70
examples/call_override.rs Normal file
View File

@ -0,0 +1,70 @@
use ethers::{
prelude::*,
providers::call_raw::RawCall,
utils::{parse_ether, Geth},
};
use std::sync::Arc;
abigen!(Greeter, "ethers-contract/tests/solidity-contracts/greeter.json",);
#[tokio::main]
async fn main() -> eyre::Result<()> {
let geth = Geth::new().spawn();
let provider = Provider::<Http>::try_from(geth.endpoint()).unwrap();
let client = Arc::new(provider);
// Both empty accounts
let target: Address = "0x6fC21092DA55B392b045eD78F4732bff3C580e2c".parse()?;
let from: Address = "0x295a70b2de5e3953354a6a8344e616ed314d7251".parse()?;
// Override the sender's balance for the call
let pay_amt = parse_ether(1u64)?;
let tx = TransactionRequest::pay(target, pay_amt).from(from);
let state = call_raw::balance(from, pay_amt * 2);
// The call succeeds as if the sender had sufficient balance
client.call_raw(&tx.into()).state(&state).await.expect("balance override");
// Get the runtime bytecode for the Greeter contract using eth_call to
// simulate the deploy transaction
let deploy = Greeter::deploy(client.clone(), "Hi".to_string())?;
let runtime_bytecode = deploy.call_raw().await?;
// Instantiate a Greeter, though no bytecode exists at the target address
let greeter = Greeter::new(target, client.clone());
// Override the target account's code, simulating a call to Greeter.greet()
// as if the Greeter contract was deployed at the target address
let state = call_raw::code(target, runtime_bytecode.clone());
let res = greeter.greet().call_raw().state(&state).await?;
// greet() returns the empty string, because the target account's storage is empty
assert_eq!(&res, "");
// Encode the greeting string as solidity expects it to be stored
let greeting = "Hello, world";
let greet_slot = H256::zero();
let greet_val = encode_string_for_storage(greeting);
// Override the target account's code and storage
let mut state = call_raw::state();
state.account(target).code(runtime_bytecode.clone()).store(greet_slot, greet_val);
let res = greeter.greet().call_raw().state(&state).await?;
// The call returns "Hello, world"
assert_eq!(&res, greeting);
Ok(())
}
// Solidity stores strings shorter than 32 bytes in a single storage slot,
// with the lowest order byte storing 2 * length and the higher order
// bytes storing the string data (left aligned)
fn encode_string_for_storage(s: &str) -> H256 {
let mut bytes = s.as_bytes().to_vec();
let len = bytes.len();
assert!(len < 32, "longer strings aren't stored in a single slot");
bytes.resize(31, 0);
bytes.push(len as u8 * 2);
H256::from_slice(&bytes)
}