Shell Protocol - 0xVolcano's results

Table of Contents

• Table of Contents
• Pack variables together(Save 1 SLOT: 2100 Gas)
• No need to assign default values to struct(not similar to what the bot reported)

Pack variables together(Save 1 SLOT: 2100 Gas)

https://github.com/code-423n4/2023-11-shellprotocol/blob/485de7383cdf88284ee6bcf2926fb7c19e9fb257/src/ocean/Ocean.sol#L108-L109

File: /src/ocean/Ocean.sol
108:    uint256 _ERC1155InteractionStatus;
109:    uint256 _ERC721InteractionStatus;

The above two variables are set in the following https://github.com/code-423n4/2023-11-shellprotocol/blob/485de7383cdf88284ee6bcf2926fb7c19e9fb257/src/ocean/Ocean.sol#L169-L174

169:    constructor(string memory uri_) OceanERC1155(uri_) {
170:        unwrapFeeDivisor = type(uint256).max;
171:        _ERC1155InteractionStatus = NOT_INTERACTION;
172:        _ERC721InteractionStatus = NOT_INTERACTION;
173:        WRAPPED_ETHER_ID = _calculateOceanId(address(0x4574686572), 0); // hexadecimal(ascii("Ether"))
174:    }

Note, we are assigning them values of NOT_INTERACTION which is a constant variable with value 1. The other place we assign them is in the function _erc1155Wrap() where we now use the variable INTERACTION which is a constant variable with value 1 We can safely reduce their size from uint256 to uint128 since the only two values we ever set are 1 and 2

diff --git a/src/ocean/Ocean.sol b/src/ocean/Ocean.sol
index 1b687be..d3ac600 100644
--- a/src/ocean/Ocean.sol
+++ b/src/ocean/Ocean.sol
@@ -105,8 +105,8 @@ contract Ocean is IOceanInteractions, IOceanFeeChange, OceanERC1155, IERC721Rece
     /// @dev adapted from OpenZeppelin Reentrancy Guard
     uint256 constant NOT_INTERACTION = 1;
     uint256 constant INTERACTION = 2;
-    uint256 _ERC1155InteractionStatus;
-    uint256 _ERC721InteractionStatus;
+    uint128 _ERC1155InteractionStatus;
+    uint128 _ERC721InteractionStatus;

     event ChangeUnwrapFee(uint256 oldFee, uint256 newFee, address sender);
     event Erc20Wrap(

No need to assign default values to struct(not similar to what the bot reported)

https://github.com/code-423n4/2023-11-shellprotocol/blob/485de7383cdf88284ee6bcf2926fb7c19e9fb257/src/adapters/CurveTricryptoAdapter.sol#L118-L140

File: /src/adapters/CurveTricryptoAdapter.sol
118:    function wrapToken(uint256 tokenId, uint256 amount) internal override {
119:        Interaction memory interaction;

121:        if (tokenId == zToken) {
122:            interaction = Interaction({
123:                interactionTypeAndAddress: 0,
124:                inputToken: 0,
125:                outputToken: 0,
126:                specifiedAmount: 0,
127:                metadata: bytes32(0)
128:            });
129:            IOceanInteractions(ocean).doInteraction{ value: amount }(interaction);
130:        } else {
131:            interaction = Interaction({
132:                interactionTypeAndAddress: _fetchInteractionId(underlying[tokenId], uint256(InteractionType.WrapErc20)),
133:                inputToken: 0,
134:                outputToken: 0,
135:                specifiedAmount: amount,
136:                metadata: bytes32(0)
137:            });
138:            IOceanInteractions(ocean).doInteraction(interaction);
139:        }
140:    }

We are defining a variable of type Interaction which is a struct. At no point is this struct being stored in storage so any values assigned only last inside the blocks they are assigned. This means that , every time the struct is being used, we start off at the default values of all variables in the struct, there is no need therefore to assign the same default value

@@ -119,22 +119,11 @@ contract CurveTricryptoAdapter is OceanAdapter {
         Interaction memory interaction;

         if (tokenId == zToken) {
-            interaction = Interaction({
-                interactionTypeAndAddress: 0,
-                inputToken: 0,
-                outputToken: 0,
-                specifiedAmount: 0,
-                metadata: bytes32(0)
-            });
             IOceanInteractions(ocean).doInteraction{ value: amount }(interaction);
         } else {
-            interaction = Interaction({
-                interactionTypeAndAddress: _fetchInteractionId(underlying[tokenId], uint256(InteractionType.WrapErc20)),
-                inputToken: 0,
-                outputToken: 0,
-                specifiedAmount: amount,
-                metadata: bytes32(0)
-            });
+            interaction.interactionTypeAndAddress = _fetchInteractionId(underlying[tokenId], uint256(InteractionType.WrapErc20));
+            interaction.specifiedAmount = amount;
+
             IOceanInteractions(ocean).doInteraction(interaction);
         }
     }

https://github.com/code-423n4/2023-11-shellprotocol/blob/485de7383cdf88284ee6bcf2926fb7c19e9fb257/src/adapters/CurveTricryptoAdapter.sol#L147-L169

File: /src/adapters/CurveTricryptoAdapter.sol
147:    function unwrapToken(uint256 tokenId, uint256 amount) internal override {
148:        Interaction memory interaction;

150:        if (tokenId == zToken) {
151:            interaction = Interaction({
152:                interactionTypeAndAddress: _fetchInteractionId(address(0), uint256(InteractionType.UnwrapEther)),
153:                inputToken: 0,
154:                outputToken: 0,
155:                specifiedAmount: amount,
156:                metadata: bytes32(0)
157:            });
158:        } else {
159:            interaction = Interaction({
160:                interactionTypeAndAddress: _fetchInteractionId(underlying[tokenId], uint256(InteractionType.UnwrapErc20)),
161:                inputToken: 0,
162:                outputToken: 0,
163:                specifiedAmount: amount,
164:                metadata: bytes32(0)
165:            });
166:        }

168:        IOceanInteractions(ocean).doInteraction(interaction);
169:    }

      * @dev unwraps the underlying token from the Ocean
@@ -148,21 +148,13 @@ contract CurveTricryptoAdapter is OceanAdapter {
         Interaction memory interaction;

         if (tokenId == zToken) {
-            interaction = Interaction({
-                interactionTypeAndAddress: _fetchInteractionId(address(0), uint256(InteractionType.UnwrapEther)),
-                inputToken: 0,
-                outputToken: 0,
-                specifiedAmount: amount,
-                metadata: bytes32(0)
-            });
+                interaction.interactionTypeAndAddress = _fetchInteractionId(address(0), uint256(InteractionType.UnwrapEther));
+                interaction.specifiedAmount = amount;
+
         } else {
-            interaction = Interaction({
-                interactionTypeAndAddress: _fetchInteractionId(underlying[tokenId], uint256(InteractionType.UnwrapErc20)),
-                inputToken: 0,
-                outputToken: 0,
-                specifiedAmount: amount,
-                metadata: bytes32(0)
-            });
+                interaction.interactionTypeAndAddress = _fetchInteractionId(underlying[tokenId], uint256(InteractionType.UnwrapErc20));
+                interaction.specifiedAmount = amount;
+
         }

         IOceanInteractions(ocean).doInteraction(interaction);

Similar scenarios

https://github.com/code-423n4/2023-11-shellprotocol/blob/485de7383cdf88284ee6bcf2926fb7c19e9fb257/src/adapters/Curve2PoolAdapter.sol#L102-L114

File: /src/adapters/Curve2PoolAdapter.sol
102:    function wrapToken(uint256 tokenId, uint256 amount) internal override {
103:        address tokenAddress = underlying[tokenId];

105:        Interaction memory interaction = Interaction({
106:            interactionTypeAndAddress: _fetchInteractionId(tokenAddress, uint256(InteractionType.WrapErc20)),
107:            inputToken: 0,
108:            outputToken: 0,
109:            specifiedAmount: amount,
110:            metadata: bytes32(0)
111:        });

113:        IOceanInteractions(ocean).doInteraction(interaction);
114:    }

https://github.com/code-423n4/2023-11-shellprotocol/blob/485de7383cdf88284ee6bcf2926fb7c19e9fb257/src/adapters/Curve2PoolAdapter.sol#L121-L133

File: /src/adapters/Curve2PoolAdapter.sol
121:    function unwrapToken(uint256 tokenId, uint256 amount) internal override {
122:        address tokenAddress = underlying[tokenId];

124:        Interaction memory interaction = Interaction({
125:            interactionTypeAndAddress: _fetchInteractionId(tokenAddress, uint256(InteractionType.UnwrapErc20)),
126:            inputToken: 0,
127:            outputToken: 0,
128:            specifiedAmount: amount,
129:            metadata: bytes32(0)
130:        });

132:        IOceanInteractions(ocean).doInteraction(interaction);
133:    }