Static Analysis: forgotten return statements (#866)

src/app/staticanalysis/modules/abstractAstView.js

@@ -64,7 +64,8 @@ abstractAstView.prototype.build_visit = function (relevantNodeFilter) {
         relevantNodes: [],
         modifierInvocations: [],
         localVariables: getLocalVariables(node),
-        parameters: getLocalParameters(node)
+        parameters: getLocalParameters(node),
+        returns: getReturnParameters(node)
       })
       // push back relevant nodes to their the current fn if any
       getCurrentContract(that).relevantNodes.map((item) => {
@@ -155,6 +156,15 @@ function getLocalParameters (funcNode) {
   return getLocalVariables(common.getFunctionOrModifierDefinitionParameterPart(funcNode)).map(common.getType)
 }
 
+function getReturnParameters (funcNode) {
+  return getLocalVariables(common.getFunctionOrModifierDefinitionReturnParameterPart(funcNode)).map((n) => {
+    return {
+      type: common.getType(n),
+      name: common.getDeclaredVariableName(n)
+    }
+  })
+}
+
 function getLocalVariables (funcNode) {
   var locals = []
   new AstWalker().walk(funcNode, {'*': function (node) {

src/app/staticanalysis/modules/list.js

@@ -8,5 +8,6 @@ module.exports = [
   require('./inlineAssembly'),
   require('./blockTimestamp'),
   require('./lowLevelCalls'),
-  require('./blockBlockhash')
+  require('./blockBlockhash'),
+  require('./noReturn')
 ]

src/app/staticanalysis/modules/noReturn.js

+var name = 'no return: '
+var desc = 'Function with return type is not returning'
+var categories = require('./categories')
+var common = require('./staticAnalysisCommon')
+var AbstractAst = require('./abstractAstView')
+
+function noReturn () {
+  this.abstractAst = new AbstractAst()
+
+  this.visit = this.abstractAst.build_visit(
+    (node) => common.isReturn(node) || common.isAssignment(node)
+  )
+
+  this.report = this.abstractAst.build_report(report)
+}
+
+noReturn.prototype.visit = function () { throw new Error('noReturn.js no visit function set upon construction') }
+
+noReturn.prototype.report = function () { throw new Error('noReturn.js no report function set upon construction') }
+
+function report (contracts, multipleContractsWithSameName) {
+  var warnings = []
+
+  contracts.forEach((contract) => {
+    contract.functions.filter((func) => common.hasFunctionBody(func.node)).forEach((func) => {
+      var funcName = common.getFullQuallyfiedFuncDefinitionIdent(contract.node, func.node, func.parameters)
+      if (hasNamedAndUnnamedReturns(func)) {
+        warnings.push({
+          warning: `${funcName}: Mixing of named and unnamed return parameters is not advised.`,
+          location: func.src
+        })
+      } else if (shouldReturn(func) && !(hasReturnStatement(func) || (hasNamedReturns(func) && hasAssignToAllNamedReturns(func)))) {
+        warnings.push({
+          warning: `${funcName}: Defines a return type but never explicitly returns a value.`,
+          location: func.src
+        })
+      }
+    })
+  })
+
+  return warnings
+}
+
+function shouldReturn (func) {
+  return func.returns.length > 0
+}
+
+function hasReturnStatement (func) {
+  return func.relevantNodes.filter(common.isReturn).length > 0
+}
+
+function hasAssignToAllNamedReturns (func) {
+  var namedReturns = func.returns.filter((n) => n.name.length > 0).map((n) => n.name)
+  var assignedVars = func.relevantNodes.filter(common.isAssignment).map(common.getEffectedVariableName)
+  var diff = namedReturns.filter(e => !assignedVars.includes(e))
+  return diff.length === 0
+}
+
+function hasNamedReturns (func) {
+  return func.returns.filter((n) => n.name.length > 0).length > 0
+}
+
+function hasNamedAndUnnamedReturns (func) {
+  return func.returns.filter((n) => n.name.length === 0).length > 0 &&
+          hasNamedReturns(func)
+}
+
+module.exports = {
+  name: name,
+  description: desc,
+  category: categories.MISC,
+  Module: noReturn
+}

src/app/staticanalysis/modules/staticAnalysisCommon.js

@@ -18,7 +18,8 @@ var nodeTypes = {
   USERDEFINEDTYPENAME: 'UserDefinedTypeName',
   INLINEASSEMBLY: 'InlineAssembly',
   BLOCK: 'Block',
-  NEWEXPRESSION: 'NewExpression'
+  NEWEXPRESSION: 'NewExpression',
+  RETURN: 'Return'
 }
 
 var basicTypes = {
@@ -212,7 +213,7 @@ function getFunctionDefinitionName (funcDef) {
  * @return {string} name of contract inherited from
  */
 function getInheritsFromName (inheritsNode) {
-  if (!isInheritanceSpecifier(inheritsNode)) throw new Error('staticAnalysisCommon.js: not an InheritanceSpecifier node Node')
+  if (!isInheritanceSpecifier(inheritsNode)) throw new Error('staticAnalysisCommon.js: not an InheritanceSpecifier Node')
   return inheritsNode.children[0].attributes.name
 }
 
@@ -224,7 +225,7 @@ function getInheritsFromName (inheritsNode) {
  * @return {string} variable name
  */
 function getDeclaredVariableName (varDeclNode) {
-  if (!isVariableDeclaration(varDeclNode)) throw new Error('staticAnalysisCommon.js: not an variable declaration')
+  if (!isVariableDeclaration(varDeclNode)) throw new Error('staticAnalysisCommon.js: not a variable declaration')
   return varDeclNode.attributes.name
 }
 
@@ -239,7 +240,7 @@ function getDeclaredVariableName (varDeclNode) {
  * @return {list variable declaration} state variable node list
  */
 function getStateVariableDeclarationsFormContractNode (contractNode) {
-  if (!isContractDefinition(contractNode)) throw new Error('staticAnalysisCommon.js: not an contract definition declaration')
+  if (!isContractDefinition(contractNode)) throw new Error('staticAnalysisCommon.js: not a contract definition declaration')
   if (!contractNode.children) return []
   return contractNode.children.filter((el) => isVariableDeclaration(el))
 }
@@ -252,11 +253,23 @@ function getStateVariableDeclarationsFormContractNode (contractNode) {
  * @return {parameterlist node} parameterlist node
  */
 function getFunctionOrModifierDefinitionParameterPart (funcNode) {
-  if (!isFunctionDefinition(funcNode) && !isModifierDefinition(funcNode)) throw new Error('staticAnalysisCommon.js: not an function definition')
+  if (!isFunctionDefinition(funcNode) && !isModifierDefinition(funcNode)) throw new Error('staticAnalysisCommon.js: not a function definition')
   return funcNode.children[0]
 }
 
 /**
+ * Returns return parameter node for a function or modifier definition, Throws on wrong node.
+ * Example:
+ * function bar(uint a, uint b) returns (bool a, bool b) => bool a, bool b
+ * @funcNode {ASTNode} Contract Definition node
+ * @return {parameterlist node} parameterlist node
+ */
+function getFunctionOrModifierDefinitionReturnParameterPart (funcNode) {
+  if (!isFunctionDefinition(funcNode) && !isModifierDefinition(funcNode)) throw new Error('staticAnalysisCommon.js: not a function definition')
+  return funcNode.children[1]
+}
+
+/**
  * Extracts the parameter types for a function type signature
  * Example:
  * function(uint a, uint b) returns (bool) => uint a, uint b
@@ -340,6 +353,10 @@ function isVariableDeclaration (node) {
   return nodeType(node, exactMatch(nodeTypes.VARIABLEDECLARATION))
 }
 
+function isReturn (node) {
+  return nodeType(node, exactMatch(nodeTypes.RETURN))
+}
+
 function isInheritanceSpecifier (node) {
   return nodeType(node, exactMatch(nodeTypes.INHERITANCESPECIFIER))
 }
@@ -742,6 +759,7 @@ module.exports = {
   getFullQuallyfiedFuncDefinitionIdent: getFullQuallyfiedFuncDefinitionIdent,
   getStateVariableDeclarationsFormContractNode: getStateVariableDeclarationsFormContractNode,
   getFunctionOrModifierDefinitionParameterPart: getFunctionOrModifierDefinitionParameterPart,
+  getFunctionOrModifierDefinitionReturnParameterPart: getFunctionOrModifierDefinitionReturnParameterPart,
 
   // #################### Complex Node Identification
   hasFunctionBody: hasFunctionBody,
@@ -783,6 +801,7 @@ module.exports = {
   isConstantFunction: isConstantFunction,
   isInlineAssembly: isInlineAssembly,
   isNewExpression: isNewExpression,
+  isReturn: isReturn,
 
   // #################### Constants
   nodeTypes: nodeTypes,

test/staticanalysis/staticAnalysisIntegration-test.js

@@ -27,7 +27,8 @@ var testFiles = [
   'globals.sol',
   'library.sol',
   'transfer.sol',
-  'ctor.sol'
+  'ctor.sol',
+  'forgottenReturn.sol'
 ]
 
 var testFileAsts = {}
@@ -58,7 +59,8 @@ test('Integration test thisLocal.js', function (t) {
     'globals.sol': 0,
     'library.sol': 0,
     'transfer.sol': 0,
-    'ctor.sol': 0
+    'ctor.sol': 0,
+    'forgottenReturn.sol': 0
   }
 
   runModuleOnFiles(module, t, (file, report) => {
@@ -87,7 +89,8 @@ test('Integration test checksEffectsInteraction.js', function (t) {
     'globals.sol': 1,
     'library.sol': 1,
     'transfer.sol': 1,
-    'ctor.sol': 0
+    'ctor.sol': 0,
+    'forgottenReturn.sol': 0
   }
 
   runModuleOnFiles(module, t, (file, report) => {
@@ -116,7 +119,8 @@ test('Integration test constantFunctions.js', function (t) {
     'globals.sol': 0,
     'library.sol': 1,
     'transfer.sol': 0,
-    'ctor.sol': 0
+    'ctor.sol': 0,
+    'forgottenReturn.sol': 0
   }
 
   runModuleOnFiles(module, t, (file, report) => {
@@ -145,7 +149,8 @@ test('Integration test inlineAssembly.js', function (t) {
     'globals.sol': 0,
     'library.sol': 0,
     'transfer.sol': 0,
-    'ctor.sol': 0
+    'ctor.sol': 0,
+    'forgottenReturn.sol': 0
   }
 
   runModuleOnFiles(module, t, (file, report) => {
@@ -174,7 +179,8 @@ test('Integration test txOrigin.js', function (t) {
     'globals.sol': 1,
     'library.sol': 0,
     'transfer.sol': 0,
-    'ctor.sol': 0
+    'ctor.sol': 0,
+    'forgottenReturn.sol': 0
   }
 
   runModuleOnFiles(module, t, (file, report) => {
@@ -203,7 +209,8 @@ test('Integration test gasCosts.js', function (t) {
     'globals.sol': 1,
     'library.sol': 1,
     'transfer.sol': 1,
-    'ctor.sol': 0
+    'ctor.sol': 0,
+    'forgottenReturn.sol': 3
   }
 
   runModuleOnFiles(module, t, (file, report) => {
@@ -232,7 +239,8 @@ test('Integration test similarVariableNames.js', function (t) {
     'globals.sol': 0,
     'library.sol': 0,
     'transfer.sol': 0,
-    'ctor.sol': 1
+    'ctor.sol': 1,
+    'forgottenReturn.sol': 0
   }
 
   runModuleOnFiles(module, t, (file, report) => {
@@ -261,7 +269,8 @@ test('Integration test inlineAssembly.js', function (t) {
     'globals.sol': 0,
     'library.sol': 0,
     'transfer.sol': 0,
-    'ctor.sol': 0
+    'ctor.sol': 0,
+    'forgottenReturn.sol': 0
   }
 
   runModuleOnFiles(module, t, (file, report) => {
@@ -290,7 +299,8 @@ test('Integration test blockTimestamp.js', function (t) {
     'globals.sol': 2,
     'library.sol': 0,
     'transfer.sol': 0,
-    'ctor.sol': 0
+    'ctor.sol': 0,
+    'forgottenReturn.sol': 0
   }
 
   runModuleOnFiles(module, t, (file, report) => {
@@ -319,7 +329,8 @@ test('Integration test lowLevelCalls.js', function (t) {
     'globals.sol': 1,
     'library.sol': 1,
     'transfer.sol': 0,
-    'ctor.sol': 0
+    'ctor.sol': 0,
+    'forgottenReturn.sol': 0
   }
 
   runModuleOnFiles(module, t, (file, report) => {
@@ -348,7 +359,8 @@ test('Integration test blockBlockhash.js', function (t) {
     'globals.sol': 0, // was 1 !! @TODO
     'library.sol': 0,
     'transfer.sol': 0,
-    'ctor.sol': 0
+    'ctor.sol': 0,
+    'forgottenReturn.sol': 0
   }
 
   runModuleOnFiles(module, t, (file, report) => {
@@ -356,6 +368,36 @@ test('Integration test blockBlockhash.js', function (t) {
   })
 })
 
+test('Integration test noReturn.js', function (t) {
+  t.plan(testFiles.length)
+
+  var module = require('../../src/app/staticanalysis/modules/noReturn')
+
+  var lengthCheck = {
+    'KingOfTheEtherThrone.sol': 0,
+    'assembly.sol': 1,
+    'ballot.sol': 0,
+    'ballot_reentrant.sol': 0,
+    'ballot_withoutWarnings.sol': 0,
+    'cross_contract.sol': 0,
+    'inheritance.sol': 0,
+    'modifier1.sol': 1,
+    'modifier2.sol': 0,
+    'notReentrant.sol': 0,
+    'structReentrant.sol': 0,
+    'thisLocal.sol': 1,
+    'globals.sol': 0,
+    'library.sol': 0,
+    'transfer.sol': 0,
+    'ctor.sol': 0,
+    'forgottenReturn.sol': 1
+  }
+
+  runModuleOnFiles(module, t, (file, report) => {
+    t.equal(report.length, lengthCheck[file], `${file} has right amount of noReturn warnings`)
+  })
+})
+
 // #################### Helpers
 function runModuleOnFiles (module, t, cb) {
   var statRunner = new StatRunner()

test/staticanalysis/test-contracts/forgottenReturn.sol

+contract Sheep {
+   string public name;
+   string public dna;
+   bool g = true;
+   function Sheep(string _name, string _dna) {
+       name = _name;
+       dna = _dna;
+    }
+
+    function geneticallyEngineer(string _dna) returns (bool) {
+       dna = _dna;
+   }
+}
\ No newline at end of file