From 963f1baa33b3108b032e3a438b2afc05cf69740e Mon Sep 17 00:00:00 2001
From: POTHURI HARIKA <cb.en.p2cys21018@cb.students.amrita.edu>
Date: Thu, 15 Jun 2023 12:28:51 +0530
Subject: [PATCH] Upload New File
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+# Analysis of Smart Contract Security Vulnerabilities and Tools 
+     <br/>    <br/>
+ <br/>
+
+
+## SOLIDITY_UNUSED_FUNCTION_SHOULD_BE_EXTERNAL
+### Rule Description
+<p>
+ A function with <code>public</code> visibility modifier that is not called internally. Changing visibility level to <code>external</code> increases code readability. Moreover, in many cases functions with <code>external</code> visibility modifier spend less gas comparing to functions with <code>public</code> visibility modifier.
+</p>
+
+### Solidity-Rules
+
+ 
+
+```
+(contractDefinition | libraryDefinition)//functionDefinition
+ <!-- Looks for public visibility -->
+ [visibleType[text()[1] = "public"]]
+ <!-- check that there are no function calls in contract -->
+ [identifier
+ [not(text()[1]
+ = ancestor::sourceUnit//functionCall/functionName/identifier/text()[1])
+ ]
+ ]
+```
+
+ 
+
+```
+functionCall
+ [functionName/identifier[text()[1] = "keccak256"]]
+ [callArguments/tupleExpression[count(expression) > 1]]
+```
+
+ 
+
+```
+functionFallBackDefinition/visibleType[text()[1] != "external"]
+```
+
+ 
+
+```
+functionDefinition
+ [not(visibleType) or visibleType[text()[1] != "external"]]
+ //parameter
+ [
+ typeName[text()[1] = "[]"]
+ or typeName/elementaryTypeName
+ [text()[1] = "bytes" or text()[1] = "string"]
+ or typeName//identifier
+ [text()[1]
+ = ancestor::contractDefinition//structDefinition/identifier/text()[1]
+ ]
+ ]
+ [not(storageLocation)]
+```
+
+ 
+
+```
+functionDefinition
+ //variableDeclaration
+ [
+ typeName[text()[1] = "[]"]
+ or typeName/elementaryTypeName
+ [text()[1] = "bytes" or text()[1] = "string"]
+ or typeName//identifier
+ [text()[1]
+ = ancestor::contractDefinition//structDefinition/identifier/text()[1]
+ ]
+ ]
+ [not(storageLocation)]
+```
+
+### Sample Code
+
+```
+pragma solidity 0.6.0;
+
+abstract contract T {
+ function f0(uint256 a) pure external virtual returns (uint256);
+}
+
+contract Test is T {
+
+ // <yes> <report> SOLIDITY_UNUSED_FUNCTION_SHOULD_BE_EXTERNAL 73ufc1
+ function badf1() public pure returns (uint256){
+ return 5;
+ }
+
+ // <yes> <report> SOLIDITY_UNUSED_FUNCTION_SHOULD_BE_EXTERNAL 73ufc1
+ function badf2(uint256 a) pure public returns (uint256){
+ require(a > 7);
+ return 5;
+ }
+
+ function notbadf2(uint256 a) pure public returns (uint256){
+ require(a > 7);
+ return 5;
+ }
+
+ function f0(uint256 a) pure external override returns (uint256){
+ require(a > 7);
+ return 5;
+ }
+
+ function f1() private pure returns (uint256){
+ return 5;
+ }
+
+ function f2(uint256 a) private pure returns (uint256){
+ require(a > 7);
+ return 5;
+ }
+
+ function f3() public pure returns (uint256){
+ return 5;
+ }
+
+ function f4(uint256 a) public pure returns (uint256){
+ require(a > 7);
+ return 5;
+ }
+
+ function useFunctions() private returns(uint256) {
+ uint256 temp = f3();
+ temp = f4(9);
+ return temp;
+ }
+}
+
+contract Child is Test {
+ function useOne() private {
+ notbadf2(54);
+ }
+}
+
+interface ITest {
+ function notUsed() public;
+}
+```
+
+### Abstract Syntax Tree
+
+[Click Here](https://astexplorer.net/#/gist/909531a8249b0be7bbbe8db57f7bd024/90dedc267f05e61db8e9d805e05321719855f5ac) to view the AST for the above code. Code generated from AST Explorer using _solidity-parser-antlr-0.4.11_
+
+### Code Result
+
+```
+ruleId: SOLIDITY_VISIBILITY
+patternId: 23rt6g
+severity: 1
+line: 62
+column: 23
+content: public
+
+SOLIDITY_VISIBILITY :1
+```
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