feat(SoundCloud): Add Enable offline sync patch (#3407)

Co-authored-by: bewzusore <bewzusore>
Co-authored-by: oSumAtrIX <johan.melkonyan1@web.de>
Co-authored-by: BenCat07 <BenCat07@gitlab.com>

api/revanced-patches.api

@@ -1050,6 +1050,12 @@ public final class app/revanced/patches/soundcloud/analytics/DisableTelemetryPat
 	public synthetic fun execute (Lapp/revanced/patcher/data/Context;)V
 }
 
+public final class app/revanced/patches/soundcloud/offlinesync/EnableOfflineSyncPatch : app/revanced/patcher/patch/BytecodePatch {
+	public static final field INSTANCE Lapp/revanced/patches/soundcloud/offlinesync/EnableOfflineSyncPatch;
+	public fun execute (Lapp/revanced/patcher/data/BytecodeContext;)V
+	public synthetic fun execute (Lapp/revanced/patcher/data/Context;)V
+}
+
 public final class app/revanced/patches/spotify/layout/theme/CustomThemePatch : app/revanced/patcher/patch/ResourcePatch {
 	public static final field INSTANCE Lapp/revanced/patches/spotify/layout/theme/CustomThemePatch;
 	public synthetic fun execute (Lapp/revanced/patcher/data/Context;)V

src/main/kotlin/app/revanced/patches/soundcloud/ad/HideAdsPatch.kt

@@ -10,7 +10,7 @@ import app.revanced.patcher.patch.annotation.CompatiblePackage
 import app.revanced.patcher.patch.annotation.Patch
 import app.revanced.patcher.util.smali.ExternalLabel
 import app.revanced.patches.soundcloud.ad.fingerprints.InterceptFingerprint
-import app.revanced.patches.soundcloud.ad.fingerprints.FeatureConstructorFingerprint
+import app.revanced.patches.soundcloud.shared.fingerprints.FeatureConstructorFingerprint
 import app.revanced.patches.soundcloud.ad.fingerprints.UserConsumerPlanConstructorFingerprint
 import app.revanced.util.resultOrThrow
 

src/main/kotlin/app/revanced/patches/soundcloud/offlinesync/EnableOfflineSyncPatch.kt

@@ -0,0 +1,83 @@
+package app.revanced.patches.soundcloud.offlinesync
+
+import app.revanced.patcher.data.BytecodeContext
+import app.revanced.patcher.extensions.InstructionExtensions.addInstruction
+import app.revanced.patcher.extensions.InstructionExtensions.addInstructionsWithLabels
+import app.revanced.patcher.extensions.InstructionExtensions.getInstruction
+import app.revanced.patcher.extensions.InstructionExtensions.getInstructions
+import app.revanced.patcher.extensions.InstructionExtensions.replaceInstruction
+import app.revanced.patcher.patch.BytecodePatch
+import app.revanced.patcher.patch.annotation.CompatiblePackage
+import app.revanced.patcher.patch.annotation.Patch
+import app.revanced.patcher.util.smali.ExternalLabel
+import app.revanced.patches.soundcloud.offlinesync.fingerprints.DownloadOperationsHeaderVerificationFingerprint
+import app.revanced.patches.soundcloud.offlinesync.fingerprints.DownloadOperationsURLBuilderFingerprint
+import app.revanced.patches.soundcloud.shared.fingerprints.FeatureConstructorFingerprint
+import app.revanced.util.getReference
+import app.revanced.util.resultOrThrow
+import com.android.tools.smali.dexlib2.Opcode
+import com.android.tools.smali.dexlib2.iface.instruction.OneRegisterInstruction
+import com.android.tools.smali.dexlib2.iface.reference.FieldReference
+
+@Patch(
+    name = "Enable offline sync",
+    compatiblePackages = [CompatiblePackage("com.soundcloud.android")],
+)
+@Suppress("unused")
+object EnableOfflineSyncPatch : BytecodePatch(
+    setOf(
+        FeatureConstructorFingerprint, DownloadOperationsURLBuilderFingerprint,
+        DownloadOperationsHeaderVerificationFingerprint
+    ),
+) {
+    override fun execute(context: BytecodeContext) {
+        // Enable the feature to allow offline track syncing by modifying the JSON server response.
+        // This method is the constructor of a class representing a "Feature" object parsed from JSON data.
+        // p1 is the name of the feature.
+        // p2 is true if the feature is enabled, false otherwise.
+        FeatureConstructorFingerprint.resultOrThrow().mutableMethod.apply {
+            val afterCheckNotNullIndex = 2
+
+            addInstructionsWithLabels(
+                afterCheckNotNullIndex,
+                """
+                    const-string v0, "offline_sync"
+                    invoke-virtual { p1, v0 }, Ljava/lang/String;->equals(Ljava/lang/Object;)Z
+                    move-result v0
+                    if-eqz v0, :skip
+                    const/4 p2, 0x1
+                """,
+                ExternalLabel("skip", getInstruction(afterCheckNotNullIndex)),
+            )
+        }
+
+        // Patch the URL builder to use the HTTPS_STREAM endpoint
+        // instead of the offline sync endpoint to downloading the track.
+        DownloadOperationsURLBuilderFingerprint.resultOrThrow().mutableMethod.apply {
+            val getEndpointsEnumFieldIndex = 1
+            val getEndpointsEnumFieldInstruction = getInstruction<OneRegisterInstruction>(getEndpointsEnumFieldIndex)
+
+            val targetRegister = getEndpointsEnumFieldInstruction.registerA
+            val endpointsType = getEndpointsEnumFieldInstruction.getReference<FieldReference>()!!.type
+
+            replaceInstruction(
+                getEndpointsEnumFieldIndex,
+                "sget-object v$targetRegister, $endpointsType->HTTPS_STREAM:$endpointsType"
+            )
+        }
+
+        // The HTTPS_STREAM endpoint does not return the necessary headers for offline sync.
+        // Mock the headers to prevent the app from crashing by setting them to empty strings.
+        // The headers are all cosmetic and do not affect the functionality of the app.
+        DownloadOperationsHeaderVerificationFingerprint.resultOrThrow().mutableMethod.apply {
+            // The first three null checks need to be patched.
+            getInstructions().asSequence().filter {
+                it.opcode == Opcode.IF_EQZ
+            }.take(3).map { it.location.index }.forEach { nullCheckIndex ->
+                val headerStringRegister = getInstruction<OneRegisterInstruction>(nullCheckIndex).registerA
+
+                addInstruction(nullCheckIndex, "const-string v$headerStringRegister, \"\"")
+            }
+        }
+    }
+}

src/main/kotlin/app/revanced/patches/soundcloud/offlinesync/fingerprints/DownloadOperationsHeaderVerificationFingerprint.kt

@@ -0,0 +1,21 @@
+package app.revanced.patches.soundcloud.offlinesync.fingerprints
+
+import app.revanced.patcher.extensions.or
+import app.revanced.patcher.fingerprint.MethodFingerprint
+import com.android.tools.smali.dexlib2.AccessFlags
+import com.android.tools.smali.dexlib2.Opcode
+
+internal object DownloadOperationsHeaderVerificationFingerprint : MethodFingerprint(
+    returnType = "V",
+    accessFlags = AccessFlags.PUBLIC or AccessFlags.FINAL,
+    parameters = listOf("L","L"),
+    opcodes = listOf(
+        Opcode.CONST_STRING,
+        Opcode.INVOKE_VIRTUAL,
+        Opcode.MOVE_RESULT_OBJECT,
+        Opcode.CONST_STRING
+    ),
+    customFingerprint = { _, classDef ->
+        classDef.sourceFile == "DownloadOperations.kt"
+    }
+)

src/main/kotlin/app/revanced/patches/soundcloud/offlinesync/fingerprints/DownloadOperationsURLBuilderFingerprint.kt

@@ -0,0 +1,20 @@
+package app.revanced.patches.soundcloud.offlinesync.fingerprints
+
+import app.revanced.patcher.extensions.or
+import app.revanced.patcher.fingerprint.MethodFingerprint
+import com.android.tools.smali.dexlib2.AccessFlags
+import com.android.tools.smali.dexlib2.Opcode
+
+internal object DownloadOperationsURLBuilderFingerprint : MethodFingerprint(
+    returnType = "Ljava/lang/String",
+    accessFlags = AccessFlags.PUBLIC or AccessFlags.FINAL,
+    parameters = listOf("L","L"),
+    opcodes = listOf(
+        Opcode.IGET_OBJECT,
+        Opcode.SGET_OBJECT,
+        Opcode.FILLED_NEW_ARRAY
+    ),
+    customFingerprint = { _, classDef ->
+        classDef.sourceFile == "DownloadOperations.kt"
+    }
+)

src/main/kotlin/app/revanced/patches/soundcloud/shared/fingerprints/FeatureConstructorFingerprint.kt

@@ -1,4 +1,4 @@
-package app.revanced.patches.soundcloud.ad.fingerprints
+package app.revanced.patches.soundcloud.shared.fingerprints
 
 import app.revanced.patcher.extensions.or
 import app.revanced.patcher.fingerprint.MethodFingerprint