Provide basic tolerance to EIP-1559 data

Test for the envelope 'type' if 0 or not present we assume legacy and can continue, otherwise abort as it is 1559 [or future] and we don't know its encoding
Added some basic garbage-in garbage out checks to prevent calculations from generating an overflow. This will mean what comes out is garbage, but at least it didn't crash.

Author: mloit

Sources/web3swift/Transaction/EthereumTransaction.swift

@@ -29,7 +29,7 @@ public struct EthereumTransaction: CustomStringConvertible {
         get{
             if (self.r == BigUInt(0) && self.s == BigUInt(0)) {
                 return self.v
-            } else if (self.v == BigUInt(27) || self.v == BigUInt(28)) {
+            } else if (self.v == BigUInt(27) || self.v == BigUInt(28) || self.v < BigUInt(35)) {
                 return nil
             } else {
                 return ((self.v - BigUInt(1)) / BigUInt(2)) - BigUInt(17)
@@ -125,11 +125,12 @@ public struct EthereumTransaction: CustomStringConvertible {
         } else if self.v >= 27 && self.v <= 30 {
             d = BigUInt(27)
         }
-        if (self.chainID != nil && self.chainID != BigUInt(0)) {
+        if (self.chainID != nil && self.chainID != BigUInt(0) && self.v >= (d + self.chainID! + self.chainID!)) {
             normalizedV = self.v - d - self.chainID! - self.chainID!
-        } else if (inferedChainID != nil) {
+        } else if (inferedChainID != nil  && self.v >= (d + self.inferedChainID! + self.inferedChainID!)) {
             normalizedV = self.v - d - inferedChainID! - inferedChainID!
         } else {
+            if(d > v) { d = 0 }
             normalizedV = self.v - d
         }
         guard let vData = normalizedV.serialize().setLengthLeft(1) else {return nil}

Sources/web3swift/Web3/Web3+Structures.swift

@@ -110,12 +110,20 @@ extension EthereumTransaction:Decodable {
         case r
         case s
         case value
+        case type  // present in EIP-1559 transaction objects
     }
 
     public init(from decoder: Decoder) throws {
         let options = try TransactionOptions(from: decoder)
         let container = try decoder.container(keyedBy: CodingKeys.self)
 
+        // test to see if it is a EIP-1559 wrapper
+        let envelope = try decodeHexToBigUInt(container, key: .type, allowOptional: true)
+        if( (envelope != nil) && (envelope! != BigInt(0)) ) {
+            // if present and non-sero we are a new wrapper we can't decode
+            throw Web3Error.dataError
+        }
+
         var data = try decodeHexToData(container, key: .data, allowOptional: true)
         if data != nil {
             self.data = data!