Local receipt parsing + IntroEligibility #302

aboedo · 2020-07-30T15:39:49Z

Documentation on apple receipt format:

https://www.notion.so/revenuecat/Receipt-parsing-iOS-c3221c5591a045a7bab2780f6c819664

Overview of the solution:

ASN1 and containers

The receipt is stored as an ASN1Container, which recursively holds asn1 containers. Every component and every field in the receipt is stored as an ASN1 container.
Their basic structure is a TLV triplet - Type, Length, Value.
The type is identifier + encoding type (primitive vs constructed, tells you whether it's recursive)
The length is one or multiple bytes, and they indicate the length of the Value
The Value can be one of numerous ASN1 types, and it might hold other ASN1 containers.

Code structure:

The code is split into the main entrypoint, Basic Types, Builders and Data Converters.

Receipt Parser

The main entry point for local receipt parsing is ReceiptParser.
This class has one public method, which parses an AppleReceipt from a binary stream of data, and returns if possible, throws if the data can't be interpreted as a receipt.

To get the payload of the receipt, ReceiptParser interprets the binary stream as an ASN1 container, and then looks inside (recursively) for a specific container: an objectIdentifier of type data. If it's found, the container immediately after it will hold the payload.

Basic types

The basic types (AppleReceipt, ASN1Container, ASN1ObjectIdentifier, InAppPurchase) are just data models with only the needed properties, and querying methods in the case of AppleReceipt.

Builders

Each of the builders holds the logic to create basic types from binary payloads or ASN1 containers.

Data Converters

The files in this group hold converters and general converters for binary types into Swift types.

aboedo · 2020-07-30T17:16:13Z

...ample.xcodeproj/xcshareddata/xcschemes/WatchExample - Local Environment (Xcode 12+).xcscheme

@@ -55,16 +55,18 @@
      debugServiceExtension = "internal"
      allowLocationSimulation = "YES"
      notificationPayloadFile = "WatchExample Extension/PushNotificationPayload.apns">
-      <BuildableProductRunnable


this just makes the schemes runnable on network devices.

feel free to skip.

aboedo · 2020-07-30T17:17:36Z

Purchases/SwiftSources/IntroEligibilityCalculator.swift

@@ -11,17 +11,17 @@ import StoreKit

 public class IntroEligibilityCalculator: NSObject {
    private let productsManager: ProductsManager
-    private let localReceiptParser: LocalReceiptParser


It's not technically local if it receives NSData, the data could come from anywhere.

Purchases/SwiftSources/LocalReceiptParsing/BasicTypes/ASN1ObjectIdentifier.swift

aboedo · 2020-07-30T17:20:35Z

Purchases/SwiftSources/LocalReceiptParsing/BasicTypes/AppleReceipt.swift

+        return Set(productIdentifiers)
+    }
+
+    var asDict: [String: Any] {


this bit is just to make debugging easier.

aboedo · 2020-07-30T17:21:39Z

Purchases/SwiftSources/LocalReceiptParsing/BasicTypes/InAppPurchase.swift

+         cancellationDate = 1712,
+         isInTrialPeriod = 1713,
+         isInIntroOfferPeriod = 1719,
+         promotionalOfferIdentifier = 1721


promotionalOfferIdentifier, isInTrialPeriod and productType seem to work and are useful, but they aren't documented.
I made them optional since they're not documented, just in case they change in the future.

aboedo · 2020-07-30T17:34:54Z

Purchases/SwiftSources/LocalReceiptParsing/DataConverters/UInt8+Extensions.swift

+private extension UInt8 {
+    func maskForRange(_ range: UInt8) -> UInt8 {
+        guard 0 <= range && range <= 8 else { fatalError("range must be between 1 and 8") }
+        switch range {


https://twitter.com/ctrlshifti/status/1288745146759000064?s=21 😂
but I couldn't think of an alternative that was easier to understand at a glance, and it's just a few cases

aboedo · 2020-07-30T17:35:44Z

Purchases/SwiftSources/LocalReceiptParsing/ReceiptParser.swift

+}
+
+private extension ReceiptParser {
+    func findASN1Container(withObjectId objectId: ASN1ObjectIdentifier,


this would be reused if we wanted other parts of the receipt, like the signature

PurchasesTests/Resources/receipts/receiptAsData.txt

aboedo · 2020-07-30T17:37:02Z

PurchasesTests/Resources/receipts/verifyReceipt.txt

@@ -0,0 +1,369 @@
+{


I figured it might be useful to have the file around for testing purposes, but it differs enough from the actual receipt that I'll probably replace it with a JSON representation of the actual receipt.

aboedo · 2020-07-30T17:37:42Z

PurchasesTests/SwiftSources/LocalReceiptParsing/LocalReceiptParserTests.swift

+        let receiptData = sampleReceiptData()
+
+        expect {
+            let receipt = try ReceiptParser().parse(from: receiptData)
+            print(receipt.description)
+            return receipt
+        } .notTo(throwError())


this is clearly not testing anything yet, next up is working on testing everything thoroughly

vegaro · 2020-08-03T19:47:46Z

Purchases/SwiftSources/LocalReceiptParsing/ReceiptParser.swift

+        let intData = [UInt8](data)
+
+        let asn1Container = try containerBuilder.build(fromPayload: ArraySlice(intData))
+        guard let receiptASN1Container = try findASN1Container(withObjectId: .data, inContainer: asn1Container) else {


This .data confused me a little bit with the data from parameters

👍 I'll make it more explicit and also rename data

vegaro · 2020-08-03T20:25:41Z

Purchases/SwiftSources/LocalReceiptParsing/BasicTypes/ASN1Container.swift

+
+struct ASN1Container {
+    let containerClass: ASN1Class
+    let containerType: ASN1Type


I thought the Type was composed by identifier + class + encoding type. But here, containerType is actually the identifier? I was expecting this ASN1Type to be another struct that had an identifier, a class and an encoding type. That might be too much, but I think containerType should be at least indicate that it is the identifier of the type, and not the whole type.

vegaro · 2020-08-03T20:31:14Z

Purchases/SwiftSources/LocalReceiptParsing/ReceiptParser.swift

+        if container.encodingType == .constructed {
+            var currentPayload = container.internalPayload
+            for internalContainer in container.internalContainers {
+                currentPayload = currentPayload.dropFirst(internalContainer.totalBytes)


I am a little bit confused about this dropFirst. Why is it needed?

Also, you're only using currentPayload in line 44. The next iteration, it's applying the dropFirst on the currentPayload created in the previous iteration? Why?

per our convo the other day, I'm going to refactor this to remove the currentPayload stuff since it's no longer needed - it was needed before I extracted this method.

vegaro · 2020-08-03T21:23:09Z

Purchases/SwiftSources/LocalReceiptParsing/Builders/ASN1ContainerBuilder.swift

+        let lengthBit = firstByte.bitAtIndex(0)
+        let isShortLength = lengthBit == 0
+
+        let firstByteValue = UInt(firstByte.valueInRange(from: 1, to: 7))


Since this is only used in the case that's not short length, I would move this inside the else branch. I would probably do:

let totalLengthOctets = Int(firstByte.valueInRange(from: 1, to: 7))

Since that's the same right?

vegaro · 2020-08-03T21:25:05Z

Purchases/SwiftSources/LocalReceiptParsing/Builders/ASN1ContainerBuilder.swift

+        let containerType = try extractType(byte: firstByte)
+        let length = try extractLength(data: payload.dropFirst())
+        let identifierTotalBytes = 1
+        let metadataBytes = identifierTotalBytes + length.totalBytes


Why this +1?

I would probably call this numberOfMetadataBytes

I am not convinced about the naming for totalBytes and identifierTotalBytes, I had to dig in the code to understand that it is the number of bytes used to represent the length or the identifier

I'm not convinced about the naming for any of these either XD I just kept finding more similar stuff to add on and naming got difficult. I'll try to improve it.

Updated naming here, lmk what you think

vegaro · 2020-08-03T21:25:38Z

Purchases/SwiftSources/LocalReceiptParsing/Builders/ASN1ContainerBuilder.swift

+struct ASN1ContainerBuilder {
+
+    func build(fromPayload payload: ArraySlice<UInt8>) throws -> ASN1Container {
+        guard payload.count >= 2,


Why this >= 2?

Oh, is it because it needs to be > 1, being the first byte the type

It might actually need to be >= 3, but I haven't been able to find docs about it.
there has to be at least one byte for identifier and one for length, I'm not sure whether the value needs to have at least one byte.

vegaro · 2020-08-03T21:27:45Z

Purchases/SwiftSources/LocalReceiptParsing/BasicTypes/ASN1Container.swift

+
+struct ASN1Length {
+    let value: UInt
+    let totalBytes: Int


Why is value UInt and totalBytes Int?

no good reason tbh. At first I was using UInt a lot more since the inability for the values to be negative made sense, but it's a total hassle because most useful methods require Int (like the array slicing methods dropFirst, prefix, etc).
I'll refactor value to Int since it removes the need for quite a bit of casting.

vegaro · 2020-08-03T21:31:41Z

Purchases/SwiftSources/LocalReceiptParsing/Builders/ASN1ContainerBuilder.swift

+        let identifierTotalBytes = 1
+        let metadataBytes = identifierTotalBytes + length.totalBytes
+
+        guard payload.count - metadataBytes >= Int(length.value) else { throw ReceiptReadingError.asn1ParsingError }


What is this check trying to prevent? Shouldn't it be something like if metadataBytes != Int(length.value) instead?

vegaro · 2020-08-03T22:01:41Z

Purchases/SwiftSources/LocalReceiptParsing/Builders/InAppPurchaseBuilder.swift

+        var promotionalOfferIdentifier: String?
+
+        for internalContainer in container.internalContainers {
+            guard internalContainer.internalContainers.count == 3 else { fatalError() }


Maybe adding a message in that fatalError would help

vegaro · 2020-08-03T22:03:07Z

Purchases/SwiftSources/LocalReceiptParsing/Builders/AppleReceiptBuilder.swift

+        guard let internalContainer = container.internalContainers.first else { fatalError() }
+        let receiptContainer = try containerBuilder.build(fromPayload: internalContainer.internalPayload)
+        for receiptAttribute in receiptContainer.internalContainers {
+            let typeContainer = receiptAttribute.internalContainers[0]


In the InAppPurchaseBuilder, there's a check for the number of internalContainers which I think would be helpful to add here

vegaro · 2020-08-03T22:06:34Z

Purchases/SwiftSources/LocalReceiptParsing/Builders/InAppPurchaseBuilder.swift

+            let nonOptionalOriginalPurchaseDate = originalPurchaseDate,
+            let nonOptionalIsInIntroOfferPeriod = isInIntroOfferPeriod,
+            let nonOptionalWebOrderLineItemId = webOrderLineItemId else {
+            throw ReceiptReadingError.inAppParsingError


I think this is very smart

vegaro · 2020-08-03T22:12:43Z

Purchases/SwiftSources/LocalReceiptParsing/Builders/ASN1ObjectIdentifierBuilder.swift

+    func build(fromPayload payload: ArraySlice<UInt8>) -> ASN1ObjectIdentifier? {
+        guard let firstByte = payload.first else { fatalError("invalid object identifier") }
+
+        var oidBytes: [UInt] = []


can we rename this oid?

absolutely. I don't know what got into me.

also, bytes is wrong - it makes you expect [UInt8] instead of [UInt].

Purchases/SwiftSources/LocalReceiptParsing/TPInAppReceipt/LICENSE

vegaro · 2020-08-07T15:53:48Z

Purchases/SwiftSources/LocalReceiptParsing/Builders/ASN1ContainerBuilder.swift

+        let containerIdentifier = try extractIdentifier(byte: firstByte)
+        let length = try extractLength(data: payload.dropFirst())
+        let bytesUsedForIdentifier = 1
+        let bytesUsedForMetadata = bytesUsedForIdentifier + length.bytesUsedForLength


I think this naming looks better yes

aboedo · 2020-08-12T21:00:56Z

Purchases/SwiftSources/IntroEligibilityCalculator.swift

+            let receipt = try receiptParser.parse(from: receiptData)
+            let purchasedProductIdsWithIntroOffers = receipt.purchasedIntroOfferOrFreeTrialProductIdentifiers()
+
+            let allProductIdentifiers = candidateProductIdentifiers.union(purchasedProductIdsWithIntroOffers)


join all product ids so that we only issue one products request, we separate them again in the completion block

aboedo · 2020-08-12T21:06:22Z

Purchases/Public/RCPurchases.m

-                    CALL_IF_SET_ON_MAIN_THREAD(receiveEligibility, result);
+                                 completionBlock:(RCReceiveIntroEligibilityBlock)receiveEligibility
+{
+    [self receiptData:^(NSData *data) {


the logic here should eventually be moved out of purchases and into something like a higher-level intro eligibility manager, which decides whether to use the local or backend version.
This PR is gigantic enough as it is, though.

aboedo · 2020-08-12T21:21:38Z

PurchasesTests/Purchasing/StoreKitRequestFetcherTests.swift

@@ -16,46 +16,6 @@ import Purchases

 class StoreKitRequestFetcher: XCTestCase {

-    class MockProductResponse: SKProductsResponse {


moved to separate file for reuse

aboedo · 2020-08-12T21:22:23Z

PurchasesTests/Resources/receipts/verifyReceiptSample1.txt

@@ -0,0 +1,369 @@
+{


this isn't used, but it's a useful reference when writing tests for the other sample, since it has the /verifyReceipt version of the same file

aboedo · 2020-08-12T21:23:27Z

PurchasesTests/TestHelpers/ContainerFactory.swift

+protocol BuildableReceiptAttributeType {
+    var rawValue: Int { get }
+}
+extension InAppPurchaseAttributeType: BuildableReceiptAttributeType {}
+extension ReceiptAttributeType: BuildableReceiptAttributeType {}


this is a swift trick - it makes it easy for a method to accept values for either enum, like a union

equivalent of python type hinting's Union

aboedo · 2020-08-12T21:25:45Z

PurchasesTests/TestHelpers/ASN1ObjectIdentifierEncoder.swift

+import Foundation
+@testable import Purchases
+
+class ASN1ObjectIdentifierEncoder {


this ended up being tougher than the decoder.
it's also less efficient since I didn't go crazy optimizing given that it's only for tests.

I did manually test that it outputs the correct result for all known object identifiers.

aboedo · 2020-08-12T21:28:35Z

@vegaro this is finally ready for review! let me know if you'd like me to split it up into smaller pieces, though, since tests ended up being huge.

vegaro

Haven't looked at the tests part yet

vegaro · 2020-08-13T00:54:13Z

Purchases/Public/RCPurchases.m

-              operationDispatcher:(RCOperationDispatcher *)operationDispatcher {
-
+              operationDispatcher:(RCOperationDispatcher *)operationDispatcher
+       introEligibilityCalculator:(RCIntroEligibilityCalculator *)introEligibilityCalculator  {


Suggested change

introEligibilityCalculator:(RCIntroEligibilityCalculator *)introEligibilityCalculator {

introEligibilityCalculator:(RCIntroEligibilityCalculator *)introEligibilityCalculator {

vegaro · 2020-08-13T01:04:44Z

Purchases/SwiftSources/IntroEligibilityCalculator.swift

+        }
+        do {
+            let receipt = try receiptParser.parse(from: receiptData)
+            let purchasedProductIdsWithIntroOffers = receipt.purchasedIntroOfferOrFreeTrialProductIdentifiers()


Suggested change

let purchasedProductIdsWithIntroOffers = receipt.purchasedIntroOfferOrFreeTrialProductIdentifiers()

let purchasedProductIdsWithIntroOffersOrFreeTrials = receipt.purchasedIntroOfferOrFreeTrialProductIdentifiers()

vegaro · 2020-08-13T01:06:24Z

Purchases/SwiftSources/IntroEligibilityCalculator.swift

+            let allProductIdentifiers = candidateProductIdentifiers.union(purchasedProductIdsWithIntroOffers)
+
+            productsManager.products(withIdentifiers: allProductIdentifiers) { allProducts in
+                let purchasedProductsWithIntroOffers = allProducts.filter { purchasedProductIdsWithIntroOffers.contains($0.productIdentifier) }


Suggested change

let purchasedProductsWithIntroOffers = allProducts.filter { purchasedProductIdsWithIntroOffers.contains($0.productIdentifier) }

let purchasedProductsWithIntroOffersOrFreeTrials = allProducts.filter { purchasedProductIdsWithIntroOffers.contains($0.productIdentifier) }

vegaro · 2020-08-13T01:10:03Z

Purchases/SwiftSources/LocalReceiptParsing/BasicTypes/ASN1Container.swift

+}
+
+enum ASN1Identifier: UInt8, CaseIterable {
+    case endOfContent = 0x00


Does this have to be 0x00 or can it be just 0

Purchases/SwiftSources/LocalReceiptParsing/Builders/ASN1ContainerBuilder.swift

+        if isShortLength {
+            return ASN1Length(value: firstByteValue, bytesUsedForLength: 1)
+        } else {
+            let totalLengthOctets = firstByteValue


aboedo · 2020-08-20T20:06:48Z

Purchases/SwiftSources/LocalReceiptParsing/ReceiptParser.swift

+            for (index, internalContainer) in container.internalContainers.enumerated() {
+                if internalContainer.containerIdentifier == .objectIdentifier {
+                    let objectIdentifier = objectIdentifierParser.build(fromPayload: internalContainer.internalPayload)
+                    if objectIdentifier == objectId && index < container.internalContainers.count - 1 {


it's just to make sure that there is a next container available after the object identifier.

vegaro · 2020-08-13T01:45:03Z

Purchases/SwiftSources/Purchasing/ProductsManager.swift

+            let productsAlreadyCached = self.cachedProductsByIdentifier.filter { key, _ in identifiers.contains(key) }
+            if productsAlreadyCached.count == identifiers.count {
+                let productsAlreadyCachedSet = Set(productsAlreadyCached.values)
+                NSLog("skipping products request because products were already cached. products: \(identifiers)")


We are using NSLog in this file. Should we copy the logs utils we have to be able to use them in this swift files?

once we get the new RCLog stuff Tina's working on merged, we can come back and refactor this to use it

vegaro · 2020-08-13T01:46:32Z

Purchases/SwiftSources/Purchasing/ProductsManager.swift

+
+            if let existingHandlers = self.completionHandlers[identifiers] {
+                NSLog("found an existing request for products: \(identifiers), appending to completion")
+                self.completionHandlers[identifiers] = existingHandlers + [completion]


we should probably synchronize the access to completionHandlers

no need - that's what the queue is doing.
things on this file can only be executed atomically in the queue. it's a way of handling this stuff in Swift that's pretty neat.

vegaro · 2020-08-13T01:47:48Z

Purchases/SwiftSources/Purchasing/ProductsManager.swift

+            guard let requestProducts = self.productsByRequests[request] else { fatalError("couldn't find request") }
+            guard let completionBlocks = self.completionHandlers[
+                requestProducts
+                ] else { fatalError("couldn't find completion") }


I think the formatting broke here

vegaro · 2020-08-13T01:51:28Z

Purchases/SwiftSources/Purchasing/ProductsManager.swift

+            resultDict[product.productIdentifier] = product
+        }
+
+        cachedProductsByIdentifier.merge(productsByIdentifier) { (_, new) in new }


cachedProductsByIdentifier should probably be synchronized too right?

we could force these operations into the queue, but there's no way to access them publicly anyway, only through the public methods, and those do force you into the queue, so it should be thread-safe already

aboedo · 2020-08-20T20:11:44Z

I'll need to rebase, but I'm holding off until the other PRs are merged or this one gets approved to minimize conflicts

vegaro · 2020-08-21T03:59:28Z

PurchasesTests/Mocks/MockIntroEligibilityCalculator.swift

+                                                           completion: @escaping ([String: NSNumber], Error?) -> ()) {
+        invokedCheckTrialOrIntroductoryPriceEligibility = true
+        invokedCheckTrialOrIntroductoryPriceEligibilityCount += 1
+        invokedCheckTrialOrIntroductoryPriceEligibilityParameters = (


I think the formatting broke here

Suggested change

invokedCheckTrialOrIntroductoryPriceEligibilityParameters = (

invokedCheckTrialOrIntroductoryPriceEligibilityParameters = (receiptData, candidateProductIdentifiers)

vegaro · 2020-08-21T04:03:00Z

PurchasesTests/Mocks/MockProductsRequest.swift

+
+    override func start() {
+        startCalled = true
+        DispatchQueue.main.async {


why is this async?

so that we can test what happens when two requests are running simultaneously. also, so it's closer to what would happen in a prod environment.
we could even add an optional delay... I didn't find a need for it, but it might not be a bad addition

vegaro · 2020-08-21T04:07:01Z

PurchasesTests/PurchasesTests-Bridging-Header.h

@@ -43,4 +43,6 @@
 #include <Purchases/RCProductInfo.h>
 #include <Purchases/RCProductInfoExtractor.h>
 #include <Purchases/RCOperationDispatcher.h>
+#include <Purchases/RCIntroEligibilityCalculator.h>


You've probably explained me this 1000 times, but why do we need this here? Don't the tests use the swift headers?

LOL I don't think I have for this particular one - this is kind of a workaround because the initWith... method in RCPurchases won't be recognized by the compiler at compile-time without the symbol being imported.

I don't like it one bit, though, and we (luckily) remove the need for it in #316. But until we rebase from that one, it's needed.

vegaro · 2020-08-21T04:29:30Z

PurchasesTests/SwiftSources/LocalReceiptParsing/Builders/ASN1ContainerBuilderTests.swift

+        payloadArray.insert(constructedEncodingByte, at: 0)
+
+        let containerLenghtByte: UInt8 = UInt8(3)
+        payloadArray.insert(containerLenghtByte, at: 1)


Do you need to add the container length in this test? Also there is a typo in length

well, there has to be a header and a length for it to be a valid asn1. Without it, validations would fail

vegaro · 2020-08-21T04:41:44Z

PurchasesTests/SwiftSources/LocalReceiptParsing/Builders/ASN1ContainerBuilderTests.swift

+
+        expect { try self.containerBuilder.build(fromPayload: payload) }.to(throwError())
+    }
+}


this is very intense, I can't imagine what you went through writing this. good job

vegaro · 2020-08-21T04:56:32Z

PurchasesTests/SwiftSources/LocalReceiptParsing/Builders/ASN1ContainerBuilderTests.swift

+                                             UInt8(UInt8(subContainer1InternalPayload.count))]
+                                             + subContainer1InternalPayload
+        let subContainer2Payload: [UInt8] = [UInt8(0b1),
+                                             UInt8(UInt8(subContainer2InternalPayload.count))]


Why is this UInt8(UInt8?

probably cause I had a tough day 😂 I'll clean it up

vegaro · 2020-08-21T05:01:19Z

PurchasesTests/SwiftSources/LocalReceiptParsing/Builders/AppleReceiptBuilderTests.swift

+    func testBuildGetsExpiresDate() {
+        let expirationDate = Date.from(year: 2020, month: 7, day: 4, hour: 5, minute: 3, second: 2)
+        let expirationDateContainer = containerFactory
+            .receiptAttributeContainer(attributeType: ReceiptAttributeType.expirationDate,


Suggested change

.receiptAttributeContainer(attributeType: ReceiptAttributeType.expirationDate,

.receiptAttributeContainer(attributeType: ReceiptAttributeType.expirationDate, expirationDate)

vegaro · 2020-08-21T05:28:14Z

PurchasesTests/SwiftSources/LocalReceiptParsing/DataConverters/ISO3601DateFormatterTests.swift

+    func testDateFromBytesReturnsNilIfItCantBeParsedIntoDate() {
+        guard let stringAsBytes = "some string that isn't a date".data(using: .ascii) else { fatalError() }
+        expect(ISO3601DateFormatter.shared.date(fromBytes: ArraySlice(stringAsBytes))).to(beNil())
+    }


Should we also test what happens if the ArraySlice is empty?

yep! I'll add.

vegaro · 2020-08-21T05:33:03Z

PurchasesTests/SwiftSources/LocalReceiptParsing/DataConverters/UInt8+ExtensionsTests.swift

+        expect(UInt8(0b10000000).bitAtIndex(0)) == 1
+        expect(UInt8(0b10000000).bitAtIndex(1)) == 0
+        expect(UInt8(0b00100000).bitAtIndex(2)) == 1
+        expect(UInt8(0b11111111).bitAtIndex(3)) == 1


Since all of them are 1, the test is not really proving that it's getting the right one right? If I understand correctly, this should be:

expect(UInt8(0b00010000).bitAtIndex(3)) == 1

I might be getting this all wrong lol. Also, it's missing the case where you check for the 8th bit, you're only checking for 7 of the bits.

I don't think it's a big deal though

lol yep, fixing

vegaro

I am just a little bit confused by ASN1ObjectIdentifierEncoder but other than that EXTREMELY GOOD JOB!

aboedo · 2020-08-21T21:52:40Z

LOL I'm confused by that one as well. I'm doing a clean-up pass on it and I'll ask for a re-review

* Preparing for next version * Update RCSystemInfo.m * Update .jazzy.yaml * Update .jazzy.yaml * back to 3.6.0-SNAPSHOT added TPInAppReceipt pod, added logic to get intro eligibility from receipt finished main logic for intro eligibility small fixes to retention in closures replaced pod dependency with embedded classes added TPInAppReceipt license clean up on intro eligibility calculator updated the logic to get products info so that only one SKProductsRequest gets issued added using the cache in productsManager cleanup: used DI for the IntroEligibilityCalculator fixed TPInAppReceipt compatibility with watchOS added syncing with a queue + support for multiple concurrent requests to product manager remove api key specified os version availability for intro calculation in detail ensured that data can't be nil before sending it to parser also covered the case where receipt data is not null, but is empty added missing import remove pod from podspec added files for local testing WIP interpreting bytes from receipt added parsing of data length, added methods to make parsing individual bits and bit ranges easier added more generalized code to get asn1 containers cleanup: moved methods into UInt8 extensinos more cleanup: moved method into ASN1Container init made constructor recursive, fixed issues with indexes more iteration fixes small cleanup started unpacking InAppReceiptAttributes more decoding of attributes more decoding of attributes decoded missing attributes added algorithm for decoding object identifier started cleanup: moved stuff to a separate class cleanup, separated objectIdentifierParser WIP extracting stuff into classes added methods for easier print debugging more cleanup added more (undocummented) fields to in app purchase moved to using our own solution instead of TPInAppReceipt for intro eligibility removed TPInAppReceipt cleanup, renames, removed unused files separated inAppPurchase into its own class split extraction logic into several factories moved to using a single date formatter method naming clenaup separated ASN1ObjectIdentifier from factory small update to use DI for the date formatter more cleanup: unified duplicated logic to convert from bytes to different value types renamed file from previous commit moved more responsibility to the apple receipt factory, simplified the AppleReceipt class moved logic for querying the apple receipt into the apple receipt class moved more responsibility to the inAppPurchaseFactory and away from InAppPurchase removed redundant class LocalReceiptParser removed all force unwraps and replaced assumptions with more robust error handling and throwing custom exceptions split code into builders, basic types and utilities renamed factory -> builder renamed factory -> builder renamed Utilities -> Data Converters removed unused extractableValueType protocols added UInt8 extensions tests, simplified guard conditions added tests for ArraySlice<UInt8>+Extensions added tests for iOS3601 date formatter renamed ASN1Type -> ASN1Identifier. Added first tests for ASN1ContainerBuilder added more tests for asn1ContainerBuiler added tests for short length asn1 containers fixed rebase issues cleanup added tests for container length, added description to ASN1 errors added more details to error cases, added tests for container length removed unused property added more tests for length and internal payload made internal containers `let` since it's never modified outside of construction. added tests for asn1ContainerBuilder's building of internal containers - removed receiptAsData.txt, renamed sample receipt, added tests that compare directly against the sample receipt and serve as integration tests for local receipt parsing. small cleanup changed type of ASN1Length.value from UInt -> Int inApp -> inAppPurchase purchasedIntroOfferProductIdentifiers -> purchasedIntroOfferOrFreeTrialProductIdentifiers clean up naming oid -> objectIdentifier more naming cleanup WIP adding container factory to make tests easier added more factory methods added more logic to be able to compose receipts for testing purposes. added tests for minimal attributes in the receipt added more tests for minimal attributes added test for expires date cleanup in container factory added base code to be able to compose in app purchase containers for testing purposes added tests for minimal attributes in in-app purchases added tests for optional attributes adds tests to ensure that in-app purchase build fails if attributes are missing, fixed tests not running for in-app purchase builder. fixed bug in tests added ASN.1 object identifier encoding to be able test decoding added tests for all known object identifiers added checks for empty and invalid object identifiers cleanup added tests to check that in app purchases are correctly added to the receipt simplified ASN1ObjectIdentifierBuilder logic fixed rebase issues added some tests for ReceiptParser renamed the methods in container factory removing the redundant build prefix added remaining tests for ReceiptParser moved containerFactory into TestHelpers cleanup in IntroEligibilityCalculator, added class for tests replaced classes with mocks added more tests updated intro eligibility calculator swift name so name lookup works correctly in tests updated Swift name for other internal swift classes so we won't run into lookup issues with them added test to check that only one SKProducts call is issued added tests to check that eligibility is calculated correctly removed redundant file SKProduct+TestExtensions, replaced with mockSKProduct extracted mockProductsRequest into separate file for reuse added more tests added final tests for productsManager fixed rebase issue added link to docs for object identifiers added link to apple docs for apple receipt fields cleanup: extracted method to build internal containers added docs and extracted method for variable length quantity decoder added a couple of comments

sipersso · 2020-10-17T13:02:42Z

I noticed this featured is in the PurchasesCoreSwift module and not the Purchases... does this mean it is not meant for public use?

I am using another local receipt parser nu for legacy reasons and would like to remove that dependency.

sipersso · 2020-10-17T13:12:36Z

Hmmm.... looks like the parse method isn't public. Is this intentional?

I'd love to be able to use RevenueCat to parse local receipts. Today I have to keep another library around just to be able to do this. In some cases, the local receipt returns an original version that is different from the purchaserInfo and since my app has been converted from a paid app to freemium I am afraid to upset old customers by removing the local receipt parser.

aboedo · 2020-10-19T15:07:34Z

The local receipt parser isn't public, indeed, and it's intentional.
Its feature-set is currently limited, and is only used for very specific purposes, mostly to prevent unnecessary backend calls. But the source of truth is still the backend.
There are a couple of reasons for this:

The current implementation doesn't perform receipt validation on device, so the contents of the receipt shouldn't be relied upon.
Even if it did, security-wise it's much easier for an attacker to intercept whatever is happening on device, so the backend will always be more reliable as a source of truth.
The receipt that's on the device may not be up to date. This is likely why you're seeing different values on purchaserInfo, which comes from the backend, vs the receipt.
An apple receipt doesn't necessarily tell the whole story when it comes to a user - they may have made purchases through Android or Stripe, or have been granted promotional purchases, and none of those will be reflected on the receipt.

@sipersso I hope this answers your questions.

As for making the migration, I'd encourage you to contact our support to ensure that your transition goes smoothly. They'll be able to help you work out any kinks.

sipersso · 2020-10-19T15:19:28Z

@aboedo Thanks! Then I'll avoid using it and reach out to support for guidance.

aboedo self-assigned this Jul 30, 2020

aboedo marked this pull request as draft July 30, 2020 15:40

aboedo requested review from jeiting and vegaro July 30, 2020 17:38

aboedo added the HOLD label Jul 30, 2020

aboedo commented Jul 30, 2020

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aboedo force-pushed the local_receipt_parsing branch from d560942 to e1e68d5 Compare July 31, 2020 15:44

aboedo force-pushed the feature/local_intro_eligibility branch from 45e0446 to af73e08 Compare July 31, 2020 15:44

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aboedo changed the base branch from feature/local_intro_eligibility to develop August 3, 2020 20:55

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aboedo force-pushed the local_receipt_parsing branch 2 times, most recently from aae2652 to 1576d18 Compare August 4, 2020 20:31

aboedo mentioned this pull request Aug 4, 2020

compute intro eligibility locally #280

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aboedo force-pushed the local_receipt_parsing branch from b6913e8 to 0917ac7 Compare August 5, 2020 21:59

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aboedo force-pushed the local_receipt_parsing branch 2 times, most recently from 8402f0d to 610f4bf Compare August 11, 2020 17:43

aboedo changed the title ~~Local receipt parsing~~ Local receipt parsing + IntroEligibility Aug 12, 2020

aboedo force-pushed the local_receipt_parsing branch from e6502e6 to f880bc8 Compare August 12, 2020 20:59

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aboedo marked this pull request as ready for review August 12, 2020 21:27

aboedo requested a review from vegaro August 12, 2020 21:28

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aboedo force-pushed the local_receipt_parsing branch from 45603b8 to 5de8034 Compare August 20, 2020 19:47

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aboedo requested a review from vegaro August 21, 2020 14:40

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vegaro and others added 14 commits August 26, 2020 16:40

readability improvements from PR comments

03f9a11

another readability cleanup from PR comments

810d5dd

added empty data test case for iso date formatter

6ad5f88

more readability improvements from PR comments

20a2190

more readability improvements from PR comments

c17dade

cleaned up the code of ASN1ObjectIdentifierEncoder a bit

c78d395

cleaned up conversion from string to binary

b06b516

small cleanup

0db95a9

removed unused swift interfaces

e7e1ca3

fixed missing swift references in main project

0872817

shuffled tests into corresponding targets

2dd3342

fixed tests for purchases target

07e0064

moved more files around

5fb0247

aboedo force-pushed the local_receipt_parsing branch from 0266da2 to 5fb0247 Compare August 26, 2020 22:28

aboedo merged commit 82e575b into develop Aug 27, 2020

aboedo deleted the local_receipt_parsing branch August 27, 2020 14:15

aboedo mentioned this pull request Aug 27, 2020

release: 3.6.0-beta-2 #322

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aboedo mentioned this pull request Sep 10, 2020

Release/3.6.0 #335

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aboedo mentioned this pull request Jul 13, 2021

Release: 3.12.0 #648

Merged

		@@ -16,46 +16,6 @@ import Purchases

		class StoreKitRequestFetcher: XCTestCase {

		class MockProductResponse: SKProductsResponse {

	introEligibilityCalculator:(RCIntroEligibilityCalculator *)introEligibilityCalculator {
	introEligibilityCalculator:(RCIntroEligibilityCalculator *)introEligibilityCalculator {

	let purchasedProductIdsWithIntroOffers = receipt.purchasedIntroOfferOrFreeTrialProductIdentifiers()
	let purchasedProductIdsWithIntroOffersOrFreeTrials = receipt.purchasedIntroOfferOrFreeTrialProductIdentifiers()

	let purchasedProductsWithIntroOffers = allProducts.filter { purchasedProductIdsWithIntroOffers.contains($0.productIdentifier) }
	let purchasedProductsWithIntroOffersOrFreeTrials = allProducts.filter { purchasedProductIdsWithIntroOffers.contains($0.productIdentifier) }

	invokedCheckTrialOrIntroductoryPriceEligibilityParameters = (
	invokedCheckTrialOrIntroductoryPriceEligibilityParameters = (receiptData, candidateProductIdentifiers)

	.receiptAttributeContainer(attributeType: ReceiptAttributeType.expirationDate,
	.receiptAttributeContainer(attributeType: ReceiptAttributeType.expirationDate, expirationDate)

Local receipt parsing + IntroEligibility #302

Local receipt parsing + IntroEligibility #302

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aboedo commented Jul 30, 2020 • edited Loading

Documentation on apple receipt format:

Overview of the solution:

ASN1 and containers

Code structure:

Receipt Parser

Basic types

Builders

Data Converters

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aboedo commented Aug 12, 2020

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aboedo commented Jul 30, 2020 •

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