Merge pull request #219 from franklinsch/omit-capability-checks

Optimize runtime caller capability checks

Sources/IRGen/Function/IULIAFunction.swift

@@ -105,8 +105,6 @@ struct IULIAFunctionBody {
   }
 
   func rendered() -> String {
-    // Dynamically check the caller has appropriate caller capabilities.
-    let callerCapabilityChecks = IULIACallerCapabilityChecks(callerCapabilities: callerCapabilities).rendered(functionContext: functionContext)
     let body = renderBody(functionDeclaration.body, functionContext: functionContext)
 
     // Assign a caller capaiblity binding to a local variable.
@@ -117,7 +115,7 @@ struct IULIAFunctionBody {
       capabilityBindingDeclaration = ""
     }
 
-    return "\(callerCapabilityChecks)\(capabilityBindingDeclaration)\(body)"
+    return "\(capabilityBindingDeclaration)\(body)"
   }
 
   func renderBody<S : RandomAccessCollection & RangeReplaceableCollection>(_ statements: S, functionContext: FunctionContext) -> String where S.Element == AST.Statement, S.Index == Int {

Sources/IRGen/IULIAContract.swift

@@ -37,7 +37,7 @@ struct IULIAContract {
     let publicFunctions = functions.filter { $0.functionDeclaration.isPublic }
 
     // Create a function selector, to determine which function is called in the Ethereum transaction.
-    let functionSelector = IULIAFunctionSelector(functions: publicFunctions)
+    let functionSelector = IULIAFunctionSelector(functions: publicFunctions, enclosingType: contractDeclaration.identifier.name, environment: environment)
     let selectorCode = functionSelector.rendered().indented(by: 6)
 
     // Generate code for each function in the structs.

Sources/IRGen/Runtime/IULIAFunctionSelector.swift

@@ -6,10 +6,13 @@
 //
 
 import CryptoSwift
+import AST
 
 /// Runtime code in IULIA which determines which function to call based on the Ethereum's transaction payload.
 struct IULIAFunctionSelector {
   var functions: [IULIAFunction]
+  var enclosingType: RawTypeIdentifier
+  var environment: Environment
 
   func rendered() -> String {
     let cases = renderCases()
@@ -30,14 +33,18 @@ struct IULIAFunctionSelector {
       return """
 
       case \(functionHash) /* \(function.mangledSignature()) */ {
-        \(renderCaseBody(function: function))
+        \(renderCaseBody(function: function).indented(by: 2))
       }
       
       """
     }.joined()
   }
 
   func renderCaseBody(function: IULIAFunction) -> String {
+    // Dynamically check the caller has appropriate caller capabilities.
+    let callerCapabilities = function.callerCapabilities
+    let callerCapabilityChecks = IULIACallerCapabilityChecks(callerCapabilities: callerCapabilities).rendered(enclosingType: enclosingType, environment: environment)
+
     let arguments = function.parameterCanonicalTypes.enumerated().map { arg -> String in
       let (index, type) = arg
       switch type {
@@ -50,10 +57,49 @@ struct IULIAFunctionSelector {
 
     if let resultType = function.resultCanonicalType {
       switch resultType {
-      case .address, .uint256, .bytes32: return IULIARuntimeFunction.return32Bytes(value: call)
+      case .address, .uint256, .bytes32: return callerCapabilityChecks + "\n" + IULIARuntimeFunction.return32Bytes(value: call)
       }
     }
 
-    return call
+    return callerCapabilityChecks + "\n" + call
   }
 }
+
+/// Checks whether the caller of a function has appropriate caller capabilities.
+struct IULIACallerCapabilityChecks {
+  var callerCapabilities: [CallerCapability]
+
+  func rendered(enclosingType: RawTypeIdentifier, environment: Environment) -> String {
+    let checks = callerCapabilities.compactMap { callerCapability -> String? in
+      guard !callerCapability.isAny else { return nil }
+
+      let type = environment.type(of: callerCapability.identifier.name, enclosingType: enclosingType)
+      let offset = environment.propertyOffset(for: callerCapability.name, enclosingType: enclosingType)!
+
+      switch type {
+      case .fixedSizeArrayType(_, let size):
+        return (0..<size).map { index in
+          let check = IULIARuntimeFunction.isValidCallerCapability(address: "sload(add(\(offset), \(index)))")
+          return "_flintCallerCheck := add(_flintCallerCheck, \(check)"
+          }.joined(separator: "\n")
+      case .arrayType(_):
+        let check = IULIARuntimeFunction.isCallerCapabilityInArray(arrayOffset: offset)
+        return "_flintCallerCheck := add(_flintCallerCheck, \(check))"
+      default:
+        let check = IULIARuntimeFunction.isValidCallerCapability(address: "sload(\(offset)))")
+        return "_flintCallerCheck := add(_flintCallerCheck, \(check)"
+      }
+    }
+
+    if !checks.isEmpty {
+      return """
+        let _flintCallerCheck := 0
+        \(checks.joined(separator: "\n"))
+        if eq(_flintCallerCheck, 0) { revert(0, 0) }
+        """ + "\n"
+    }
+
+    return ""
+  }
+}
+