Added in a little defensive coding for config message processing

Updated the config 'pendingChanges' to use the readonly version of the conf (no use blocking access)
Added code to throw and log when the config processing exceeds 50000 loops (ie. infinite loop protection)

SessionMessagingKit/SessionUtil/Config Handling/SessionUtil+Contacts.swift

@@ -40,7 +40,7 @@ internal extension SessionUtil {
         // The current users contact data is handled separately so exclude it if it's present (as that's
         // actually a bug)
         let userPublicKey: String = getUserHexEncodedPublicKey(db)
-        let targetContactData: [String: ContactData] = extractContacts(
+        let targetContactData: [String: ContactData] = try extractContacts(
             from: conf,
             latestConfigSentTimestampMs: latestConfigSentTimestampMs
         ).filter { $0.key != userPublicKey }
@@ -540,12 +540,15 @@ private extension SessionUtil {
     static func extractContacts(
         from conf: UnsafeMutablePointer<config_object>?,
         latestConfigSentTimestampMs: Int64
-    ) -> [String: ContactData] {
+    ) throws -> [String: ContactData] {
+        var infiniteLoopGuard: Int = 0
         var result: [String: ContactData] = [:]
         var contact: contacts_contact = contacts_contact()
         let contactIterator: UnsafeMutablePointer<contacts_iterator> = contacts_iterator_new(conf)
         
         while !contacts_iterator_done(contactIterator, &contact) {
+            try SessionUtil.checkLoopLimitReached(&infiniteLoopGuard, for: .contacts)
+            
             let contactId: String = String(cString: withUnsafeBytes(of: contact.session_id) { [UInt8]($0) }
                 .map { CChar($0) }
                 .nullTerminated()

SessionMessagingKit/SessionUtil/Config Handling/SessionUtil+ConvoInfoVolatile.swift

@@ -23,7 +23,7 @@ internal extension SessionUtil {
         guard conf != nil else { throw SessionUtilError.nilConfigObject }
         
         // Get the volatile thread info from the conf and local conversations
-        let volatileThreadInfo: [VolatileThreadInfo] = extractConvoVolatileInfo(from: conf)
+        let volatileThreadInfo: [VolatileThreadInfo] = try extractConvoVolatileInfo(from: conf)
         let localVolatileThreadInfo: [String: VolatileThreadInfo] = VolatileThreadInfo.fetchAll(db)
             .reduce(into: [:]) { result, next in result[next.threadId] = next }
         
@@ -314,10 +314,7 @@ public extension SessionUtil {
         openGroup: OpenGroup?
     ) -> Bool {
         return SessionUtil
-            .config(
-                for: .convoInfoVolatile,
-                publicKey: userPublicKey
-            )
+            .config(for: .convoInfoVolatile, publicKey: userPublicKey)
             .wrappedValue
             .map { conf in
                 switch threadVariant {
@@ -512,7 +509,8 @@ public extension SessionUtil {
     
     internal static func extractConvoVolatileInfo(
         from conf: UnsafeMutablePointer<config_object>?
-    ) -> [VolatileThreadInfo] {
+    ) throws -> [VolatileThreadInfo] {
+        var infiniteLoopGuard: Int = 0
         var result: [VolatileThreadInfo] = []
         var oneToOne: convo_info_volatile_1to1 = convo_info_volatile_1to1()
         var community: convo_info_volatile_community = convo_info_volatile_community()
@@ -520,6 +518,8 @@ public extension SessionUtil {
         let convoIterator: OpaquePointer = convo_info_volatile_iterator_new(conf)
 
         while !convo_info_volatile_iterator_done(convoIterator) {
+            try SessionUtil.checkLoopLimitReached(&infiniteLoopGuard, for: .convoInfoVolatile)
+            
             if convo_info_volatile_it_is_1to1(convoIterator, &oneToOne) {
                 result.append(
                     VolatileThreadInfo(

SessionMessagingKit/SessionUtil/Config Handling/SessionUtil+Shared.swift

@@ -59,10 +59,7 @@ internal extension SessionUtil {
         
         do {
             needsPush = try SessionUtil
-                .config(
-                    for: variant,
-                    publicKey: publicKey
-                )
+                .config(for: variant, publicKey: publicKey)
                 .mutate { conf in
                     guard conf != nil else { throw SessionUtilError.nilConfigObject }
                     
@@ -332,6 +329,15 @@ internal extension SessionUtil {
         // Ensure the change occurred after the last config message was handled (minus the buffer period)
         return (changeTimestampMs >= (configDumpTimestampMs - Int64(SessionUtil.configChangeBufferPeriod * 1000)))
     }
+    
+    static func checkLoopLimitReached(_ loopCounter: inout Int, for variant: ConfigDump.Variant, maxLoopCount: Int = 50000) throws {
+        loopCounter += 1
+        
+        guard loopCounter < maxLoopCount else {
+            SNLog("[libSession] Got stuck in infinite loop processing '\(variant.configMessageKind.description)' data")
+            throw SessionUtilError.processingLoopLimitReached
+        }
+    }
 }
 
 // MARK: - External Outgoing Changes

SessionMessagingKit/SessionUtil/Config Handling/SessionUtil+UserGroups.swift

@@ -34,6 +34,7 @@ internal extension SessionUtil {
         guard mergeNeedsDump else { return }
         guard conf != nil else { throw SessionUtilError.nilConfigObject }
         
+        var infiniteLoopGuard: Int = 0
         var communities: [PrioritisedData<OpenGroupUrlInfo>] = []
         var legacyGroups: [LegacyGroupInfo] = []
         var community: ugroups_community_info = ugroups_community_info()
@@ -41,6 +42,8 @@ internal extension SessionUtil {
         let groupsIterator: OpaquePointer = user_groups_iterator_new(conf)
         
         while !user_groups_iterator_done(groupsIterator) {
+            try SessionUtil.checkLoopLimitReached(&infiniteLoopGuard, for: .userGroups)
+            
             if user_groups_it_is_community(groupsIterator, &community) {
                 let server: String = String(libSessionVal: community.base_url)
                 let roomToken: String = String(libSessionVal: community.room)

SessionMessagingKit/SessionUtil/SessionUtil.swift

@@ -314,9 +314,10 @@ public enum SessionUtil {
             .compactMap { variant -> OutgoingConfResult? in
                 try SessionUtil
                     .config(for: variant, publicKey: publicKey)
-                    .mutate { conf in
+                    .wrappedValue
+                    .map { conf in
                         // Check if the config needs to be pushed
-                        guard conf != nil && config_needs_push(conf) else { return nil }
+                        guard config_needs_push(conf) else { return nil }
                         
                         var cPushData: UnsafeMutablePointer<config_push_data>!
                         let configCountInfo: String = {
@@ -375,10 +376,7 @@ public enum SessionUtil {
         publicKey: String
     ) -> ConfigDump? {
         return SessionUtil
-            .config(
-                for: message.kind.configDumpVariant,
-                publicKey: publicKey
-            )
+            .config(for: message.kind.configDumpVariant, publicKey: publicKey)
             .mutate { conf in
                 guard conf != nil else { return nil }
                 

SessionMessagingKit/SessionUtil/SessionUtilError.swift

@@ -7,4 +7,5 @@ public enum SessionUtilError: Error {
     case nilConfigObject
     case userDoesNotExist
     case getOrConstructFailedUnexpectedly
+    case processingLoopLimitReached
 }