An advanced Ethereum/EVM mobile wallet
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alpha-wallet-ios/AlphaWallet/Market/UniversalLinkHandler.swift

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14 KiB

//
// Created by James Sangalli on 24/3/18.
// Copyright © 2018 Stormbird PTE. LTD.
//
/**
* Universal link format
*
* Android requires the link to be in the form:
*
* https://www.awallet.io/[base64]
*
* The format forbids using a prefix other than 'www'.
* There needs to be text in the specific link too, in this case 'import'.
$ echo -n https://www.awallet.io/; \
echo -n 000f42405AB5B400007bee82bdd9e866b2bd114780a47f2261c684e30102030405060708092F982B84C635967A9B6306ED5789A7C1919164171E37DCCDF4B59BE54754410530818B896B7D240F56C59EBDF209062EE54DA7A3590905739674DCFDCECF3E9B1b | xxd -r -p | base64;\
https://aw.app/AA9CQFq1tAAAe+6CvdnoZrK9EUeApH8iYcaE4wECAwQFBgcICS+YK4TGNZZ6m2MG7VeJp8GRkWQXHjfczfS1m+VHVEEFMIGLiWt9JA9WxZ698gkGLuVNp6NZCQVzlnTc/c7PPpsb
* uint32: price in Szabo 000f4240
* uint32: expiry in Unix Time 5AB5B400
* bytes20: contract address 007bee82bdd9e866b2bd114780a47f2261c684e3
* Uint16[]: token indices 010203040506070809
* bytes32: 2F982B84C635967A9B6306ED5789A7C1919164171E37DCCDF4B59BE547544105
* bytes32: 30818B896B7D240F56C59EBDF209062EE54DA7A3590905739674DCFDCECF3E9B
* byte: 1b
* 1521857536, [0,1,2,3,4,5,6,7,8,9], 27, "0x2F982B84C635967A9B6306ED5789A7C1919164171E37DCCDF4B59BE547544105", "0x30818B896B7D240F56C59EBDF209062EE54DA7A3590905739674DCFDCECF3E9B" -> 0xd2bef24c7e90192426b54bf437a5eac4e220dde7
*/
import Foundation
import BigInt
private enum LinkFormat: UInt8 {
case unassigned = 0x00
case normal = 0x01
case spawnable = 0x02
case customizable = 0x03
case nativeCurrencyLink = 0x04
}
extension Array {
func chunked(into size: Int) -> [[Element]] {
return stride(from: 0, to: count, by: size).map {
Array(self[$0 ..< Swift.min($0 + size, count)])
}
}
}
public class UniversalLinkHandler {
private let server: RPCServer
init(server: RPCServer) {
self.server = server
}
//message is with 32 bytes each of price and expiry and is shortened for link
func createUniversalLink(signedOrder: SignedOrder) -> String {
let prefix = server.magicLinkPrefix.description
let message = formatMessageForLink(signedOrder: signedOrder)
let signature = signedOrder.signature
let link = (message + signature).hexa2Bytes
let binaryData = Data(bytes: link)
let base64String = binaryData.base64EncodedString()
return prefix + b64SafeEncoding(base64String)
}
private func b64SafeEncoding(_ b64String: String) -> String {
let safeEncodingB64 = b64String.replacingOccurrences(of: "+", with: "-")
return safeEncodingB64.replacingOccurrences(of: "/", with: "_")
}
private func b64SafeEncodingToRegularEncoding(_ b64SafeEncodedString: String) -> String {
let regularEncodingb64 = b64SafeEncodedString.replacingOccurrences(of: "-", with: "+")
return regularEncodingb64.replacingOccurrences(of: "_", with: "/")
}
//link has shortened price and expiry and must be expanded
func parseUniversalLink(url: String, prefix: String) -> SignedOrder? {
guard url.count > prefix.count else { return nil }
let linkInfo = b64SafeEncodingToRegularEncoding(url.substring(from: prefix.count))
guard var linkBytes = Data(base64Encoded: linkInfo)?.array else { return nil }
let encodingByte = linkBytes[0]
if let format = LinkFormat(rawValue: encodingByte) {
switch format {
case .unassigned:
return handleNormalLink(linkBytes: linkBytes)
case .normal:
//new link format, remove extra byte and continue
linkBytes.remove(at: 0)
return handleNormalLink(linkBytes: linkBytes)
case .spawnable:
return handleSpawnableLink(linkBytes: linkBytes)
case .customizable:
return handleSpawnableLink(linkBytes: linkBytes)
case .nativeCurrencyLink:
return handleNativeCurrencyDropLinks(linkBytes: linkBytes)
}
} else {
return nil
}
}
private func handleNormalLink(linkBytes: [UInt8]) -> SignedOrder? {
let price = getPriceFromLinkBytes(linkBytes: linkBytes)
let expiry = getExpiryFromLinkBytes(linkBytes: linkBytes)
guard let contractAddress = getNonNullContractAddressFromLinkBytes(linkBytes: linkBytes) else { return nil }
let tokenIndices = getTokenIndicesFromLinkBytes(linkBytes: linkBytes)
guard let (v, r, s) = getVRSFromLinkBytes(linkBytes: linkBytes) else { return nil }
let order = Order(
price: price,
indices: tokenIndices,
expiry: expiry,
contractAddress: contractAddress,
count: BigUInt(tokenIndices.count),
nonce: BigUInt(0),
tokenIds: [],
spawnable: false,
nativeCurrencyDrop: false
)
let message = getMessageFromOrder(order: order)
return SignedOrder(order: order, message: message, signature: "0x" + r + s + v)
}
//Note: native currency links can use szabo directly and
//don't need to be compressed into szabo from wei and vice versa
private func handleNativeCurrencyDropLinks(linkBytes: [UInt8]) -> SignedOrder? {
var bytes = linkBytes
bytes.remove(at: 0) //remove encoding byte
let prefix = Array(bytes[0...7])
let nonce = Array(bytes[8...11])
let amount = Array(bytes[12...15])
let expiry = Array(bytes[16...19])
let contractBytes = Array(bytes[20...39])
guard let contractAddress = AlphaWallet.Address(uncheckedAgainstNullAddress: Data(bytes: contractBytes).hex()) else { return nil }
let v = String(bytes[104], radix: 16)
let r = Data(bytes: Array(bytes[40...71])).hex()
let s = Data(bytes: Array(bytes[72...103])).hex()
let order = Order(
price: BigUInt(0),
indices: [UInt16](),
expiry: BigUInt(Data(bytes: expiry)),
contractAddress: contractAddress,
count: BigUInt(Data(bytes: amount)),
nonce: BigUInt(Data(bytes: nonce)),
tokenIds: [BigUInt](),
spawnable: false,
nativeCurrencyDrop: true
)
let message = getMessageFromNativeCurrencyDropLink(
prefix: prefix,
nonce: nonce,
amount: amount,
expiry: expiry,
contractAddress: contractBytes
)
return SignedOrder(order: order, message: message, signature: "0x" + r + s + v)
}
private func handleSpawnableLink(linkBytes: [UInt8]) -> SignedOrder? {
var bytes = linkBytes
bytes.remove(at: 0) //remove encoding byte
let price = getPriceFromLinkBytes(linkBytes: bytes)
let expiry = getExpiryFromLinkBytes(linkBytes: bytes)
guard let contractAddress = getNonNullContractAddressFromLinkBytes(linkBytes: bytes) else { return nil }
let tokenIds = getTokenIdsFromSpawnableLink(linkBytes: bytes)
guard let (v, r, s) = getVRSFromLinkBytes(linkBytes: bytes) else { return nil }
let order = Order(
price: price,
indices: [UInt16](),
expiry: expiry,
contractAddress: contractAddress,
count: BigUInt(tokenIds.count),
nonce: BigUInt(0),
tokenIds: tokenIds,
spawnable: true,
nativeCurrencyDrop: false
)
let message = getMessageFromOrder(order: order)
return SignedOrder(order: order, message: message, signature: "0x" + r + s + v)
}
private func getTokenIdsFromSpawnableLink(linkBytes: [UInt8]) -> [BigUInt] {
let sigPos = linkBytes.count - 65; //the last 65 bytes are the signature params
let tokenPos = 28 //tokens start at this byte
let bytes = Array(linkBytes[tokenPos..<sigPos])
let tokenIds = bytes.chunked(into: 32)
return tokenIds.map { BigUInt(Data(bytes: $0)) }
}
//we used a special encoding so that one 16 bit number could represent either one token or two
//this is for the purpose of keeping universal links as short as possible
private func decodeTokenIndices(indices: [UInt16]) -> [UInt8] {
var indicesBytes = [UInt8]()
for i in 0..<indices.count {
let index = indices[i]
if index < 128 {
let byte = UInt8(index)
indicesBytes.append(byte)
} else {
//Top 7 bits
let firstByteHigh = UInt8(128 + (index >> 8))
//bottom 8 bits
let secondByteLow = UInt8(index & 255)
indicesBytes.append(firstByteHigh)
indicesBytes.append(secondByteLow)
}
}
return indicesBytes
}
//formats price and expiry to 4 bytes
private func formatMessageForLink(signedOrder: SignedOrder) -> String {
let indices = decodeTokenIndices(indices: signedOrder.order.indices)
var messageWithSzabo = [UInt8]()
//change from wei to szabo
let priceSzabo = signedOrder.order.price / 1000000000000
let priceBytes = padTo4Bytes(priceSzabo.serialize().bytes)
let expiryBytes = padTo4Bytes(signedOrder.order.expiry.serialize().bytes)
messageWithSzabo.append(LinkFormat.normal.rawValue)
messageWithSzabo.append(contentsOf: priceBytes)
messageWithSzabo.append(contentsOf: expiryBytes)
messageWithSzabo.append(contentsOf: signedOrder.order.contractAddress.data.bytes)
messageWithSzabo.append(contentsOf: indices)
return Data(bytes: messageWithSzabo).hex()
}
private func padTo4Bytes(_ array: [UInt8]) -> [UInt8] {
guard array.count != 4 else { return array }
guard !array.isEmpty else { return [UInt8](repeating: 0, count: 4) }
guard !(array.count > 4) else { return Array(array[0...3]) }
var formattedArray = [UInt8]()
let missingDigits = 4 - array.count
for _ in 0..<missingDigits {
formattedArray.append(0)
}
formattedArray.append(contentsOf: array)
return formattedArray
}
private func getPriceFromLinkBytes(linkBytes: [UInt8]) -> BigUInt {
let priceBytes = Array(linkBytes[0...3])
let priceHex = Data(bytes: priceBytes).hex()
guard let price = BigUInt(priceHex, radix: 16) else { return BigUInt(0) }
return price * 1000000000000
}
private func getExpiryFromLinkBytes(linkBytes: [UInt8]) -> BigUInt {
let expiryBytes = Array(linkBytes[4...7])
let expiry = Data(bytes: expiryBytes).hex()
guard let expiryBigUInt = BigUInt(expiry, radix: 16) else { return BigUInt(0) }
return expiryBigUInt
}
//Specifically not for null (0x0...0) address
private func getNonNullContractAddressFromLinkBytes(linkBytes: [UInt8]) -> AlphaWallet.Address? {
let contractAddrBytes = Array(linkBytes[8...27])
return AlphaWallet.Address(string: Data(bytes: contractAddrBytes).hex())
}
private func getTokenIndicesFromLinkBytes(linkBytes: [UInt8]) -> [UInt16] {
let tokenLength = linkBytes.count - (65 + 20 + 8) - 1
var tokenIndices = [UInt16]()
var state: Int = 1
var currentIndex: UInt16 = 0
let tokenStart = 28
for i in stride(from: tokenStart, through: tokenStart + tokenLength, by: 1) {
let byte: UInt8 = linkBytes[i]
switch state {
case 1:
//8th bit is equal to 128, if not set then it is only one token and will change the state
if byte & (128) == 128 { //should be done with masks
currentIndex = UInt16((byte & 127)) << 8
state = 2
} else {
tokenIndices.append(UInt16(byte))
}
case 2:
currentIndex += UInt16(byte)
tokenIndices.append(currentIndex)
state = 1
default:
break
}
}
return tokenIndices
}
private func getVRSFromLinkBytes(linkBytes: [UInt8]) -> (String, String, String)? {
let signatureLength = 65
guard linkBytes.count >= signatureLength else { return nil }
var start = linkBytes.count - signatureLength
let r = Data(bytes: Array(linkBytes[start...start + 31])).hex()
start += 32
let s = Data(bytes: Array(linkBytes[start...start + 31])).hex()
var v = String(format: "%2X", linkBytes[linkBytes.count - 1]).trimmed
if var vInt = Int(v) {
if vInt < 5 {
vInt += Int(EthereumSigner.vitaliklizeConstant)
v = String(format: "%2X", vInt)
}
}
return (v, r, s)
}
private func getMessageFromNativeCurrencyDropLink(
prefix: [UInt8],
nonce: [UInt8],
amount: [UInt8],
expiry: [UInt8],
contractAddress: [UInt8]
) -> [UInt8] {
var message = [UInt8]()
message.append(contentsOf: prefix)
message.append(contentsOf: nonce)
message.append(contentsOf: amount)
message.append(contentsOf: expiry)
message.append(contentsOf: contractAddress)
return message
}
//price and expiry need to be 32 bytes each
private func getMessageFromOrder(order: Order) -> [UInt8] {
var message = [UInt8]()
//encode price and expiry first
let priceBytes = UniversalLinkHandler.padTo32(order.price.serialize().array)
message.append(contentsOf: priceBytes)
let expiryBytes = UniversalLinkHandler.padTo32(order.expiry.serialize().array)
message.append(contentsOf: expiryBytes)
let contractBytes = order.contractAddress.eip55String.hexa2Bytes
message.append(contentsOf: contractBytes)
let indices = OrderHandler.uInt16ArrayToUInt8(arrayOfUInt16: order.indices)
message.append(contentsOf: indices)
return message
}
static func padTo32(_ buffer: [UInt8], to count: Int = 32) -> [UInt8] {
let padCount = count - buffer.count
var padded = buffer
let padding: [UInt8] = Array(repeating: 0, count: padCount)
padded.insert(contentsOf: padding, at: 0)
return padded
}
}