Use CDN number instead of parsing identifier for attachment remote id.

app/src/androidTest/java/org/thoughtcrime/securesms/conversation/ConversationItemPreviewer.kt

@@ -138,7 +138,7 @@ class ConversationItemPreviewer {
   private fun attachment(): SignalServiceAttachmentPointer {
     return SignalServiceAttachmentPointer(
       Cdn.CDN_3.cdnNumber,
-      SignalServiceAttachmentRemoteId.from(""),
+      SignalServiceAttachmentRemoteId.from("", Cdn.CDN_3.cdnNumber),
       "image/webp",
       null,
       Optional.empty(),

app/src/benchmarkShared/java/org/signal/benchmark/setup/TestMessages.kt

@@ -146,7 +146,7 @@ object TestMessages {
   private fun imageAttachment(): SignalServiceAttachmentPointer {
     return SignalServiceAttachmentPointer(
       Cdn.S3.cdnNumber,
-      SignalServiceAttachmentRemoteId.from(""),
+      SignalServiceAttachmentRemoteId.from("", Cdn.S3.cdnNumber),
       "image/webp",
       null,
       Optional.empty(),
@@ -170,7 +170,7 @@ object TestMessages {
   private fun voiceAttachment(): SignalServiceAttachmentPointer {
     return SignalServiceAttachmentPointer(
       Cdn.S3.cdnNumber,
-      SignalServiceAttachmentRemoteId.from(""),
+      SignalServiceAttachmentRemoteId.from("", Cdn.S3.cdnNumber),
       "audio/aac",
       null,
       Optional.empty(),

app/src/main/java/org/thoughtcrime/securesms/attachments/AttachmentExtensions.kt

@@ -31,7 +31,7 @@ fun Attachment.toAttachmentPointer(context: Context): AttachmentPointer? {
   }
 
   try {
-    val remoteId = SignalServiceAttachmentRemoteId.from(attachment.remoteLocation!!)
+    val remoteId = SignalServiceAttachmentRemoteId.from(attachment.remoteLocation!!, attachment.cdn.cdnNumber)
 
     var attachmentWidth = attachment.width
     var attachmentHeight = attachment.height

app/src/main/java/org/thoughtcrime/securesms/backup/v2/DatabaseAttachmentArchiveUtil.kt

@@ -123,7 +123,7 @@ fun DatabaseAttachment.createArchiveAttachmentPointer(useArchiveCdn: Boolean): S
         throw InvalidAttachmentException("empty content id")
       }
 
-      SignalServiceAttachmentRemoteId.from(remoteLocation) to cdn.cdnNumber
+      SignalServiceAttachmentRemoteId.from(remoteLocation, cdn.cdnNumber) to cdn.cdnNumber
     }
 
     val key = Base64.decode(remoteKey)

app/src/main/java/org/thoughtcrime/securesms/backup/v2/util/ArchiveConverterExtensions.kt

@@ -87,7 +87,7 @@ fun FilePointer?.toLocalAttachment(
     AttachmentType.TRANSIT -> {
       val signalAttachmentPointer = SignalServiceAttachmentPointer(
         cdnNumber = locatorInfo.transitCdnNumber ?: Cdn.CDN_0.cdnNumber,
-        remoteId = SignalServiceAttachmentRemoteId.from(locatorInfo.transitCdnKey!!),
+        remoteId = SignalServiceAttachmentRemoteId.from(locatorInfo.transitCdnKey!!, locatorInfo.transitCdnNumber ?: Cdn.CDN_0.cdnNumber),
         contentType = contentType,
         key = locatorInfo.key.toByteArray(),
         size = Optional.ofNullable(locatorInfo.size),

app/src/main/java/org/thoughtcrime/securesms/jobs/AttachmentDownloadJob.kt

@@ -399,8 +399,8 @@ class AttachmentDownloadJob private constructor(
     }
 
     return try {
-      val remoteId = SignalServiceAttachmentRemoteId.from(attachment.remoteLocation)
       val cdnNumber = attachment.cdn.cdnNumber
+      val remoteId = SignalServiceAttachmentRemoteId.from(attachment.remoteLocation, cdnNumber)
 
       val key = Base64.decode(attachment.remoteKey)
 

app/src/main/java/org/thoughtcrime/securesms/jobs/PushSendJob.kt

@@ -282,7 +282,7 @@ abstract class PushSendJob protected constructor(parameters: Parameters) : BaseJ
     }
 
     try {
-      val remoteId = SignalServiceAttachmentRemoteId.from(attachment.remoteLocation!!)
+      val remoteId = SignalServiceAttachmentRemoteId.from(attachment.remoteLocation!!, attachment.cdn.cdnNumber)
       val key = Base64.decode(attachment.remoteKey!!)
 
       var width = attachment.width

app/src/main/java/org/thoughtcrime/securesms/util/SignalServiceTransformExtensions.kt

@@ -215,7 +215,7 @@ private fun Attachment.toAttachmentPointerProto(): Either<DataMessageError, Atta
     raise(DataMessageError.MissingAttachmentRemoteFields)
   }
 
-  val remoteIdResolved: SignalServiceAttachmentRemoteId = SignalServiceAttachmentRemoteId.from(remoteLocation)
+  val remoteIdResolved: SignalServiceAttachmentRemoteId = SignalServiceAttachmentRemoteId.from(remoteLocation, cdn.cdnNumber)
 
   val keyBytes: ByteArray = try {
     Base64.decode(remoteKey)

lib/libsignal-service/src/main/java/org/whispersystems/signalservice/api/messages/SignalServiceAttachmentRemoteId.kt

@@ -30,6 +30,9 @@ sealed interface SignalServiceAttachmentRemoteId {
 
   companion object {
 
+    /** The lowest CDN number that uses opaque string keys rather than numeric ids */
+    private const val FIRST_KEY_BASED_CDN = 3
+
     @JvmStatic
     @Throws(InvalidMessageStructureException::class)
     fun from(attachmentPointer: AttachmentPointer): SignalServiceAttachmentRemoteId {
@@ -42,13 +45,13 @@ sealed interface SignalServiceAttachmentRemoteId {
       }
     }
 
-    /**
-     * Guesses that strings which contain values parseable to `long` should use an id-based
-     * CDN path. Otherwise, use key-based CDN path.
-     */
     @JvmStatic
-    fun from(string: String): SignalServiceAttachmentRemoteId {
-      return string.toLongOrNull()?.let { V2(it) } ?: V4(string)
+    fun from(string: String, cdnNumber: Int): SignalServiceAttachmentRemoteId {
+      return if (cdnNumber >= FIRST_KEY_BASED_CDN) {
+        V4(string)
+      } else {
+        string.toLongOrNull()?.let { V2(it) } ?: V4(string)
+      }
     }
   }
 }