Fantom

Fantom

eth_getStorageAt

The eth_getStorageAt method returns the value stored at a specific storage position for a given smart contract address. This low-level method allows direct access to the contract's state variables and is crucial for contract analysis and debugging.

Use Cases

• Smart contract debugging and analysis
• Token balance verification
• Protocol governance inspection
• Proxy implementation verification
• Contract state auditing
• Storage layout validation
• DAO proposal status checking
• Contract upgrade verification

Method Details

This method provides raw access to any storage slot in a contract's storage.

Response Example

1{
2	"jsonrpc": "2.0",
3	"id": 1,
4	"result": "0x000000000000000000000000000000000000000000000000000000000000000a"
5}

Understanding Solidity Storage Layout

Solidity's storage layout follows specific rules:

1. State Variables: Stored sequentially starting from slot 0

// Storage slot 0
uint256 firstVariable;
// Storage slot 1
address secondVariable;

2. Mappings: The slot itself contains no data, but serves as a seed for computing positions

// Storage slot 2 (empty)
mapping(address => uint256) balances;
// Value stored at keccak256(abi.encode(userAddress, 2))

3. Dynamic Arrays: The slot contains the array length, data starts at keccak256(slot)

// Storage slot 3 has length
uint256[] myArray;
// Values stored at keccak256(3) + index

4. Packed Variables: Multiple variables smaller than 32 bytes are packed together

// All in storage slot 4
uint128 a;
uint64 b;
uint64 c;

Common Storage Slots

• ERC20 Total Supply: Often stored at slot 0 or 2
• ERC20 Balances Mapping: Often at slot 1 or 3
• ERC20 Allowances Mapping: Often at slot 2 or 4
• Proxy Implementation Address: For EIP-1967 proxies at 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc

Storage Inspection Tools

For complex contracts, consider using dedicated tools:

• Slither: Static analyzer that can generate storage layouts
• Tenderly: Visual debugger with storage inspection
• Hardhat: Console debugging with storage access
• Etherscan: Sometimes provides verified contract storage layouts

See also

• eth_getCode - Get the bytecode deployed at a specific address
• eth_getProof - Retrieve cryptographic proofs for account and storage values

1curl https://fantom.therpc.io \
2  -X POST \
3  -H 'Content-Type: application/json' \
4  -d '{"jsonrpc":"2.0","id":1,"method":"eth_getStorageAt","params":["0x1f9840a85d5aF5bf1D1762F925BDADdC4201F984","0x0","latest"]}'