feat(forge verify-contract): --guess-constructor-args (#6724)

* Add RpcOpts to VerifyArgs

* --guess-constructor-args

* Add support for CREATE2 deployer

* Fix artifact lookup

* Update verification tests + Test for --guess-constructor-args

* chore: clippy

* update compilation + separate function

* doc

---------

Co-authored-by: Matthias Seitz <matthias.seitz@outlook.de>

crates/forge/bin/cmd/create.rs

@@ -176,7 +176,11 @@ impl CreateArgs {
             constructor_args,
             constructor_args_path: None,
             num_of_optimizations: None,
-            etherscan: EtherscanOpts { key: self.eth.etherscan.key(), chain: Some(chain.into()) },
+            etherscan: EtherscanOpts {
+                key: self.eth.etherscan.key.clone(),
+                chain: Some(chain.into()),
+            },
+            rpc: Default::default(),
             flatten: false,
             force: false,
             skip_is_verified_check: true,
@@ -188,6 +192,7 @@ impl CreateArgs {
             via_ir: self.opts.via_ir,
             evm_version: self.opts.compiler.evm_version,
             show_standard_json_input: self.show_standard_json_input,
+            guess_constructor_args: false,
         };
 
         // Check config for Etherscan API Keys to avoid preflight check failing if no
@@ -326,6 +331,7 @@ impl CreateArgs {
             constructor_args_path: None,
             num_of_optimizations,
             etherscan: EtherscanOpts { key: self.eth.etherscan.key(), chain: Some(chain.into()) },
+            rpc: Default::default(),
             flatten: false,
             force: false,
             skip_is_verified_check: false,
@@ -337,6 +343,7 @@ impl CreateArgs {
             via_ir: self.opts.via_ir,
             evm_version: self.opts.compiler.evm_version,
             show_standard_json_input: self.show_standard_json_input,
+            guess_constructor_args: false,
         };
         println!("Waiting for {} to detect contract deployment...", verify.verifier.verifier);
         verify.run().await

crates/forge/bin/cmd/script/verify.rs

@@ -105,6 +105,7 @@ impl VerifyBundle {
                     constructor_args_path: None,
                     num_of_optimizations: self.num_of_optimizations,
                     etherscan: self.etherscan.clone(),
+                    rpc: Default::default(),
                     flatten: false,
                     force: false,
                     skip_is_verified_check: true,
@@ -116,6 +117,7 @@ impl VerifyBundle {
                     via_ir: self.via_ir,
                     evm_version: None,
                     show_standard_json_input: false,
+                    guess_constructor_args: false,
                 };
 
                 return Some(verify)

crates/forge/bin/cmd/verify/etherscan/mod.rs

@@ -1,20 +1,25 @@
 use super::{provider::VerificationProvider, VerifyArgs, VerifyCheckArgs};
 use crate::cmd::retry::RETRY_CHECK_ON_VERIFY;
 use alloy_json_abi::Function;
-use eyre::{eyre, Context, Result};
+use ethers_providers::Middleware;
+use eyre::{eyre, Context, OptionExt, Result};
 use forge::hashbrown::HashSet;
 use foundry_block_explorers::{
     errors::EtherscanError,
     utils::lookup_compiler_version,
     verify::{CodeFormat, VerifyContract},
     Client,
 };
-use foundry_cli::utils::{get_cached_entry_by_name, read_constructor_args_file, LoadConfig};
-use foundry_common::{abi::encode_function_args, retry::Retry};
+use foundry_cli::utils::{self, get_cached_entry_by_name, read_constructor_args_file, LoadConfig};
+use foundry_common::{abi::encode_function_args, retry::Retry, types::ToEthers};
 use foundry_compilers::{
-    artifacts::CompactContract, cache::CacheEntry, info::ContractInfo, Project, Solc,
+    artifacts::{BytecodeObject, CompactContract},
+    cache::CacheEntry,
+    info::ContractInfo,
+    Artifact, Project, Solc,
 };
 use foundry_config::{Chain, Config, SolcReq};
+use foundry_evm::constants::DEFAULT_CREATE2_DEPLOYER;
 use futures::FutureExt;
 use once_cell::sync::Lazy;
 use regex::Regex;
@@ -332,7 +337,7 @@ impl EtherscanVerificationProvider {
             self.source_provider(args).source(args, &project, &contract_path, &compiler_version)?;
 
         let compiler_version = format!("v{}", ensure_solc_build_metadata(compiler_version).await?);
-        let constructor_args = self.constructor_args(args, &project)?;
+        let constructor_args = self.constructor_args(args, &project, &config).await?;
         let mut verify_args =
             VerifyContract::new(args.address, contract_name, source, compiler_version)
                 .constructor_arguments(constructor_args)
@@ -435,7 +440,12 @@ impl EtherscanVerificationProvider {
     /// Return the optional encoded constructor arguments. If the path to
     /// constructor arguments was provided, read them and encode. Otherwise,
     /// return whatever was set in the [VerifyArgs] args.
-    fn constructor_args(&mut self, args: &VerifyArgs, project: &Project) -> Result<Option<String>> {
+    async fn constructor_args(
+        &mut self,
+        args: &VerifyArgs,
+        project: &Project,
+        config: &Config,
+    ) -> Result<Option<String>> {
         if let Some(ref constructor_args_path) = args.constructor_args_path {
             let (_, _, contract) = self.cache_entry(project, &args.contract).wrap_err(
                 "Cache must be enabled in order to use the `--constructor-args-path` option",
@@ -459,9 +469,74 @@ impl EtherscanVerificationProvider {
             let encoded_args = hex::encode(encoded_args);
             return Ok(Some(encoded_args[8..].into()))
         }
+        if args.guess_constructor_args {
+            return Ok(Some(self.guess_constructor_args(args, project, config).await?))
+        }
 
         Ok(args.constructor_args.clone())
     }
+
+    /// Uses Etherscan API to fetch contract creation transaction.
+    /// If transaction is a create transaction or a invocation of default CREATE2 deployer, tries to
+    /// match provided creation code with local bytecode of the target contract.
+    /// If bytecode match, returns latest bytes of on-chain creation code as constructor arguments.
+    async fn guess_constructor_args(
+        &mut self,
+        args: &VerifyArgs,
+        project: &Project,
+        config: &Config,
+    ) -> Result<String> {
+        let provider = utils::get_provider(config)?;
+        let client = self.client(
+            args.etherscan.chain.unwrap_or_default(),
+            args.verifier.verifier_url.as_deref(),
+            args.etherscan.key.as_deref(),
+            config,
+        )?;
+
+        let creation_data = client.contract_creation_data(args.address).await?;
+        let transaction = provider
+            .get_transaction(creation_data.transaction_hash.to_ethers())
+            .await?
+            .ok_or_eyre("Couldn't fetch transaction data from RPC")?;
+        let receipt = provider
+            .get_transaction_receipt(creation_data.transaction_hash.to_ethers())
+            .await?
+            .ok_or_eyre("Couldn't fetch transaction receipt from RPC")?;
+
+        let maybe_creation_code: &[u8];
+
+        if receipt.contract_address == Some(args.address.to_ethers()) {
+            maybe_creation_code = &transaction.input;
+        } else if transaction.to == Some(DEFAULT_CREATE2_DEPLOYER.to_ethers()) {
+            maybe_creation_code = &transaction.input[32..];
+        } else {
+            eyre::bail!("Fetching of constructor arguments is not supported for contracts created by contracts")
+        }
+
+        let contract_path = self.contract_path(args, project)?.to_string_lossy().into_owned();
+        let output = project.compile()?;
+        let artifact = output
+            .find(contract_path, &args.contract.name)
+            .ok_or_eyre("Contract artifact wasn't found locally")?;
+        let bytecode = artifact
+            .get_bytecode_object()
+            .ok_or_eyre("Contract artifact does not contain bytecode")?;
+
+        let bytecode = match bytecode.as_ref() {
+            BytecodeObject::Bytecode(bytes) => Ok(bytes),
+            BytecodeObject::Unlinked(_) => {
+                Err(eyre!("You have to provide correct libraries to use --guess-constructor-args"))
+            }
+        }?;
+
+        if maybe_creation_code.starts_with(bytecode) {
+            let constructor_args = &maybe_creation_code[bytecode.len()..];
+            Ok(hex::encode(constructor_args))
+        } else {
+            eyre::bail!("Local bytecode doesn't match on-chain bytecode")
+        }
+    }
 }
 
 /// Given any solc [Version] return a [Version] with build metadata

crates/forge/bin/cmd/verify/mod.rs

@@ -2,7 +2,11 @@ use super::retry::RetryArgs;
 use alloy_primitives::Address;
 use clap::{Parser, ValueHint};
 use eyre::Result;
-use foundry_cli::{opts::EtherscanOpts, utils::LoadConfig};
+use foundry_cli::{
+    opts::{EtherscanOpts, RpcOpts},
+    utils,
+    utils::LoadConfig,
+};
 use foundry_compilers::{info::ContractInfo, EvmVersion};
 use foundry_config::{figment, impl_figment_convert, impl_figment_convert_cast, Config};
 use provider::VerificationProviderType;
@@ -57,6 +61,10 @@ pub struct VerifyArgs {
     #[arg(long, value_hint = ValueHint::FilePath, value_name = "PATH")]
     pub constructor_args_path: Option<PathBuf>,
 
+    /// Try to extract constructor arguments from on-chain creation code.
+    #[arg(long)]
+    pub guess_constructor_args: bool,
+
     /// The `solc` version to use to build the smart contract.
     #[arg(long, value_name = "VERSION")]
     pub compiler_version: Option<String>,
@@ -112,6 +120,9 @@ pub struct VerifyArgs {
     #[command(flatten)]
     pub etherscan: EtherscanOpts,
 
+    #[command(flatten)]
+    pub rpc: RpcOpts,
+
     #[command(flatten)]
     pub retry: RetryArgs,
 
@@ -130,6 +141,8 @@ impl figment::Provider for VerifyArgs {
         &self,
     ) -> Result<figment::value::Map<figment::Profile, figment::value::Dict>, figment::Error> {
         let mut dict = self.etherscan.dict();
+        dict.extend(self.rpc.dict());
+
         if let Some(root) = self.root.as_ref() {
             dict.insert("root".to_string(), figment::value::Value::serialize(root)?);
         }
@@ -154,7 +167,23 @@ impl VerifyArgs {
     /// Run the verify command to submit the contract's source code for verification on etherscan
     pub async fn run(mut self) -> Result<()> {
         let config = self.load_config_emit_warnings();
-        let chain = config.chain.unwrap_or_default();
+
+        if self.guess_constructor_args && config.get_rpc_url().is_none() {
+            eyre::bail!(
+                "You have to provide a valid RPC URL to use --guess-constructor-args feature"
+            )
+        }
+
+        // If chain is not set, we try to get it from the RPC
+        // If RPC is not set, the default chain is used
+        let chain = match config.get_rpc_url() {
+            Some(_) => {
+                let provider = utils::get_provider(&config)?;
+                utils::get_chain(config.chain, provider).await?
+            }
+            None => config.chain.unwrap_or_default(),
+        };
+
         self.etherscan.chain = Some(chain);
         self.etherscan.key = config.get_etherscan_config_with_chain(Some(chain))?.map(|c| c.key);
 

crates/forge/tests/cli/verify.rs

@@ -55,6 +55,24 @@ function doStuff() external {{}}
     prj.add_source("Verify.sol", &contract).unwrap();
 }
 
+fn add_verify_target_with_constructor(prj: &TestProject) {
+    prj.add_source(
+        "Verify.sol",
+        r#"
+import {Unique} from "./unique.sol";
+contract Verify is Unique {
+    struct SomeStruct {
+        uint256 a;
+        string str;
+    }
+
+    constructor(SomeStruct memory st, address owner) {}
+}
+"#,
+    )
+    .unwrap();
+}
+
 fn parse_verification_result(cmd: &mut TestCommand, retries: u32) -> eyre::Result<()> {
     // give etherscan some time to verify the contract
     let retry = Retry::new(retries, Some(Duration::from_secs(30)));
@@ -73,6 +91,39 @@ fn parse_verification_result(cmd: &mut TestCommand, retries: u32) -> eyre::Resul
     })
 }
 
+fn await_verification_response(info: EnvExternalities, mut cmd: TestCommand) {
+    let guid = {
+        // give etherscan some time to detect the transaction
+        let retry = Retry::new(5, Some(Duration::from_secs(60)));
+        retry
+            .run(|| -> eyre::Result<String> {
+                let output = cmd.unchecked_output();
+                let out = String::from_utf8_lossy(&output.stdout);
+                utils::parse_verification_guid(&out).ok_or_else(|| {
+                    eyre::eyre!(
+                        "Failed to get guid, stdout: {}, stderr: {}",
+                        out,
+                        String::from_utf8_lossy(&output.stderr)
+                    )
+                })
+            })
+            .expect("Failed to get verify guid")
+    };
+
+    // verify-check
+    cmd.forge_fuse()
+        .arg("verify-check")
+        .arg(guid)
+        .arg("--chain-id")
+        .arg(info.chain.to_string())
+        .arg("--etherscan-api-key")
+        .arg(info.etherscan)
+        .arg("--verifier")
+        .arg(info.verifier);
+
+    parse_verification_result(&mut cmd, 6).expect("Failed to verify check")
+}
+
 fn verify_on_chain(info: Option<EnvExternalities>, prj: TestProject, mut cmd: TestCommand) {
     // only execute if keys present
     if let Some(info) = info {
@@ -98,37 +149,41 @@ fn verify_on_chain(info: Option<EnvExternalities>, prj: TestProject, mut cmd: Te
             info.verifier.to_string(),
         ]);
 
-        // `verify-contract`
-        let guid = {
-            // give etherscan some time to detect the transaction
-            let retry = Retry::new(5, Some(Duration::from_secs(60)));
-            retry
-                .run(|| -> eyre::Result<String> {
-                    let output = cmd.unchecked_output();
-                    let out = String::from_utf8_lossy(&output.stdout);
-                    utils::parse_verification_guid(&out).ok_or_else(|| {
-                        eyre::eyre!(
-                            "Failed to get guid, stdout: {}, stderr: {}",
-                            out,
-                            String::from_utf8_lossy(&output.stderr)
-                        )
-                    })
-                })
-                .expect("Failed to get verify guid")
-        };
-
-        // verify-check
-        cmd.forge_fuse()
-            .arg("verify-check")
-            .arg(guid)
-            .arg("--chain-id")
-            .arg(info.chain.to_string())
-            .arg("--etherscan-api-key")
-            .arg(info.etherscan)
-            .arg("--verifier")
-            .arg(info.verifier);
-
-        parse_verification_result(&mut cmd, 6).expect("Failed to verify check")
+        await_verification_response(info, cmd)
+    }
+}
+
+fn guess_constructor_args(info: Option<EnvExternalities>, prj: TestProject, mut cmd: TestCommand) {
+    // only execute if keys present
+    if let Some(info) = info {
+        println!("verifying on {}", info.chain);
+        add_unique(&prj);
+        add_verify_target_with_constructor(&prj);
+
+        let contract_path = "src/Verify.sol:Verify";
+        cmd.arg("create").args(info.create_args()).arg(contract_path).args(vec![
+            "--constructor-args",
+            "(239,SomeString)",
+            "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045",
+        ]);
+
+        let out = cmd.stdout_lossy();
+        let address = utils::parse_deployed_address(out.as_str())
+            .unwrap_or_else(|| panic!("Failed to parse deployer {out}"));
+
+        cmd.forge_fuse().arg("verify-contract").root_arg().args([
+            "--rpc-url".to_string(),
+            info.rpc.to_string(),
+            address,
+            contract_path.to_string(),
+            "--etherscan-api-key".to_string(),
+            info.etherscan.to_string(),
+            "--verifier".to_string(),
+            info.verifier.to_string(),
+            "--guess-constructor-args".to_string(),
+        ]);
+
+        await_verification_response(info, cmd)
     }
 }
 
@@ -174,3 +229,9 @@ forgetest!(can_verify_random_contract_sepolia, |prj, cmd| {
 forgetest!(can_create_verify_random_contract_sepolia, |prj, cmd| {
     create_verify_on_chain(EnvExternalities::sepolia(), prj, cmd);
 });
+
+// tests `create && contract-verify --guess-constructor-args && verify-check` on Goerli testnet if
+// correct env vars are set
+forgetest!(can_guess_constructor_args, |prj, cmd| {
+    guess_constructor_args(EnvExternalities::goerli(), prj, cmd);
+});