🧠 Solidity Proxy & Delegatecall Patterns

Low-level exploration of EVM execution context, storage behavior, and proxy architectures.

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📚 Topics Covered

• Delegatecall vs Call
• Execution context and msg.sender
• Storage layout and slot behavior
• Storage collision vulnerabilities
• Proxy pattern (fallback + delegatecall)
• Minimal proxy (EIP-1167 clones)

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🧪 Experiments

Delegatecall vs Call

Same function call.
Different execution context.
Different storage outcome.

• call → modifies target contract storage
• delegatecall → modifies caller contract storage

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Storage Collision

Mismatched storage layouts:

• same slot
• different meaning

Result:

• critical state overwrite (owner)

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Proxy Pattern

User interacts with proxy.

• proxy forwards calldata
• implementation executes logic
• state is stored in proxy

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Minimal Proxy (EIP-1167)

Factory deploys lightweight proxy instances.

• shared implementation
• isolated storage per instance
• cheap deployment

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⚠️ Key Insight

Delegatecall executes external code using the caller’s storage.

Storage layout must be consistent across contracts.

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🧠 Core Mental Model

• Code lives in implementation
• State lives in proxy
• Execution context defines where state changes

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📌 Summary

Same code.
Different storage.
Completely different system behavior.