Tx input parsing #16
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,36 @@ | ||
| // | ||
| // Method.swift | ||
| // Wallet | ||
| // | ||
| // Created by Stefano on 21.12.21. | ||
| // | ||
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| import Foundation | ||
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| struct MethodInfo { | ||
| let contractAddress: String | ||
| let methodId: String | ||
| let description: MethodDescription | ||
| } | ||
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| struct MethodDescription { | ||
| let stringFormat: String | ||
| let arguments: [String] | ||
| } | ||
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| extension MethodInfo: Decodable { | ||
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| enum CodingKeys : String, CodingKey { | ||
| case contractAddress = "Address" | ||
| case methodId = "MethodId" | ||
| case description = "Description" | ||
| } | ||
| } | ||
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| extension MethodDescription: Decodable { | ||
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| enum CodingKeys : String, CodingKey { | ||
| case stringFormat = "StringFormat" | ||
| case arguments = "Arguments" | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,21 @@ | ||
| <?xml version="1.0" encoding="UTF-8"?> | ||
| <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"> | ||
| <plist version="1.0"> | ||
| <array> | ||
| <dict> | ||
| <key>Description</key> | ||
| <dict> | ||
| <key>StringFormat</key> | ||
| <string>Registered %@</string> | ||
| <key>Arguments</key> | ||
| <array> | ||
| <string>name</string> | ||
| </array> | ||
| </dict> | ||
| <key>Address</key> | ||
| <string>0x283af0b28c62c092c9727f1ee09c02ca627eb7f5</string> | ||
| <key>MethodId</key> | ||
| <string>f7a16963</string> | ||
| </dict> | ||
| </array> | ||
| </plist> | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,32 @@ | ||
| // | ||
| // TransactionInput.swift | ||
| // Wallet | ||
| // | ||
| // Created by Stefano on 17.12.21. | ||
| // | ||
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| import MEWwalletKit | ||
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| typealias InputName = String | ||
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| struct TransactionInput { | ||
| let method: Method | ||
| let inputData: [InputName: InputData] | ||
| } | ||
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| struct Method { | ||
| let name: String | ||
| let signature: String | ||
| let hash: String | ||
| let inputs: [InputParameter] | ||
| } | ||
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| struct InputParameter { | ||
| let name: InputName | ||
| let type: ABI.Element.ParameterType | ||
| } | ||
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| struct InputData { | ||
| let parameter: InputParameter | ||
| let data: Any | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,63 @@ | ||
| // | ||
| // TransactionDecoder.swift | ||
| // Wallet | ||
| // | ||
| // Created by Stefano on 21.12.21. | ||
| // | ||
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| import Foundation | ||
| import MEWwalletKit | ||
| import UIKit | ||
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| protocol TransactionDecodable { | ||
| func decode(input: String, with contract: Contract) -> TransactionInput? | ||
| } | ||
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| struct TransactionDecoder: TransactionDecodable { | ||
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| func decode(input: String, with contract: Contract) -> TransactionInput? { | ||
| guard let data = contract.abi.data(using: .utf8), | ||
| let abiRecords = try? JSONDecoder().decode([ABI.Record].self, from: data) else { | ||
| return nil | ||
| } | ||
| for record in abiRecords { | ||
| let element = try? record.parse() | ||
| if case .function(let function) = element { | ||
| let signature = function.signature | ||
| let decodedMethodHash = function.methodString | ||
| let data = Data(hex: input) | ||
| guard !data.isEmpty, data.count > 4 else { return nil } | ||
| let methodHash = data[0 ..< 4].dataToHexString() | ||
| if methodHash == decodedMethodHash, let decodedInput = element?.decodeInputData(data) { | ||
|
DimitarNestorov marked this conversation as resolved.
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| let parameters = getInputParameters(of: function) | ||
| let inputData = mapToInputDataFrom(parameters: parameters, input: decodedInput) | ||
| return TransactionInput( | ||
| method: Method( | ||
| name: function.name ?? "", | ||
| signature: signature, | ||
| hash: methodHash, | ||
| inputs: parameters | ||
| ), | ||
| inputData: inputData | ||
| ) | ||
| } | ||
| } | ||
| } | ||
| return nil | ||
| } | ||
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| private func getInputParameters(of function: ABI.Element.Function) -> [InputParameter] { | ||
| function.inputs.map { InputParameter(name: $0.name, type: $0.type) } | ||
| } | ||
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| private func mapToInputDataFrom(parameters: [InputParameter], input: [String: Any]) -> [InputName: InputData] { | ||
| let inputData = parameters.compactMap { param -> (InputName, InputData)? in | ||
| guard let data = input[param.name] else { return nil } | ||
| return (param.name, InputData(parameter: param, data: data)) | ||
| } | ||
| return Dictionary( | ||
| inputData, | ||
| uniquingKeysWith: { (first, _) in first } | ||
| ) | ||
| } | ||
| } | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,75 @@ | ||
| // | ||
| // TransactionInputParser.swift | ||
| // Wallet | ||
| // | ||
| // Created by Stefano on 21.12.21. | ||
| // | ||
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| import BigInt | ||
| import Foundation | ||
| import MEWwalletKit | ||
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| protocol TransactionInputParseable { | ||
| func parse(input: [String: String], methodHash: String, contractAddress: RawAddress) -> String? | ||
| func parseToStringValues(input: TransactionInput) -> [InputName: String] | ||
| } | ||
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| typealias MethodID = String | ||
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| final class TransactionInputParser: TransactionInputParseable { | ||
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| private lazy var methodInfoLookup: [RawAddress: [MethodID: MethodInfo]] = { | ||
| let decoder = PropertyListDecoder() | ||
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| guard let url = Bundle.main.url(forResource: "MethodInfo", withExtension: "plist"), | ||
| let data = try? Data(contentsOf: url), | ||
| let methodInfo = try? decoder.decode([MethodInfo].self, from: data) else { return [:] } | ||
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| return methodInfo.reduce([RawAddress: [MethodID: MethodInfo]]()) { partialResult, info in | ||
| var methodInfo = partialResult | ||
| if methodInfo[info.contractAddress] != nil { | ||
| methodInfo[info.contractAddress]?[info.methodId] = info | ||
| } else { | ||
| methodInfo[info.contractAddress] = [info.methodId: info] | ||
| } | ||
| return methodInfo | ||
| } | ||
| }() | ||
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| func parse(input: [String: String], methodHash: String, contractAddress: RawAddress) -> String? { | ||
| guard let methodInfo = methodInfoLookup[contractAddress]?[methodHash] else { return nil } | ||
| let arguments = methodInfo.description.arguments.compactMap { input[$0] } | ||
| return String(format: methodInfo.description.stringFormat, arguments: arguments) | ||
| } | ||
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| func parseToStringValues(input: TransactionInput) -> [InputName: String] { | ||
| input.inputData.reduce([InputName: String]()) { partialResult, input in | ||
| var stringValues = partialResult | ||
| stringValues[input.key] = convertRawValueToString(inputData: input.value) | ||
| return stringValues | ||
| } | ||
| } | ||
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| private func convertRawValueToString(inputData: InputData) -> String? { | ||
|
Collaborator
Author
There was a problem hiding this comment. Just simple conversion to string values right now so we can display it on the tx history detail page for demo purposes. |
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| switch inputData.parameter.type { | ||
| case .uint: | ||
| return (inputData.data as? BigUInt).flatMap(String.init) | ||
| case .int: | ||
| return (inputData.data as? BigInt).flatMap(String.init) | ||
| case .address: | ||
| return (inputData.data as? Address).flatMap { $0.address } | ||
| case .function: | ||
| return "n/a" | ||
| case .bool: | ||
| return (inputData.data as? Bool).flatMap(String.init) | ||
| case .bytes, .dynamicBytes: | ||
| return ABIEncoder.convertToData(inputData.data as AnyObject)?.toHexString() | ||
| case .string: | ||
| return inputData.data as? String | ||
| case .array: | ||
| return "n/a" | ||
| case .tuple: | ||
| return "n/a" | ||
| } | ||
| } | ||
| } | ||
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What do you guys think of this approach? Maintaining a list of string formats per contract/methodId so we can display the tx input in a descriptive way, instead of dumping the method name and its arguments? But it's something we'd have to maintain over time...
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I think maintaining a list is a good idea. While it involves more upfront work, and the ongoing maintenance cost, it's the best approach we have so far to provide really clear, user-friendly descriptions of transactions.
One question: why a
plist? Would it not be better to put this in Swift directly, perhaps a map fromaddress+methodto a callback? This way, we can not only return text, but also other pieces of UI (logos, links, perhaps even in-wallet actions?)There was a problem hiding this comment.
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In addition to our discussions, this approach is still a bit limited as it assumes that the parameter value’s string representation can be readily displayed. However, in some cases we will need to do some further formatting, e.g. when the input parameter is a timestamp, we would like to format it in a readable way. One way we could handle this is to add an additional type argument which tells the client how to format the value. wdyt?
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Yea, I agree. What about using
String(format:_:), or another string formatting API, or a library? https://riptutorial.com/swift/example/6342/formatting-stringsThere was a problem hiding this comment.
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Right! So in the current PR
String(format:arguments:)is used (seeTransactionInputParser). So we should be able to handle different format specifiers. But if we wanted to do date formatting for example then string formats wouldn't be sufficient anymore.There are also a couple of other things to consider:
It's easy for errors to creep in here. When the list contains errors in the string format or the supplied argument names then it will be difficult to catch. We will need to think about how we can add further validation perhaps, and/or how to properly test updates in the string format list.