add support for downloading encrypted HLS streams

Changelog: changed

app/src/main/java/com/futo/platformplayer/downloads/VideoDownload.kt

@@ -47,6 +47,7 @@ import com.futo.platformplayer.states.StatePlatform
 import com.futo.platformplayer.states.StatePlugins
 import com.futo.platformplayer.toHumanBitrate
 import com.futo.platformplayer.toHumanBytesSpeed
+import com.futo.polycentric.core.hexStringToByteArray
 import hasAnySource
 import isDownloadable
 import kotlinx.coroutines.CancellationException
@@ -59,6 +60,7 @@ import kotlinx.coroutines.suspendCancellableCoroutine
 import kotlinx.coroutines.withContext
 import kotlinx.serialization.Contextual
 import kotlinx.serialization.Transient
+import java.io.ByteArrayOutputStream
 import java.io.File
 import java.io.FileOutputStream
 import java.io.IOException
@@ -69,6 +71,9 @@ import java.util.concurrent.Executors
 import java.util.concurrent.ForkJoinPool
 import java.util.concurrent.ForkJoinTask
 import java.util.concurrent.ThreadLocalRandom
+import javax.crypto.Cipher
+import javax.crypto.spec.IvParameterSpec
+import javax.crypto.spec.SecretKeySpec
 import kotlin.coroutines.resumeWithException
 import kotlin.time.times
 
@@ -564,6 +569,14 @@ class VideoDownload {
         }
     }
 
+    private fun decryptSegment(encryptedSegment: ByteArray, key: ByteArray, iv: ByteArray): ByteArray {
+        val cipher = Cipher.getInstance("AES/CBC/PKCS5Padding")
+        val secretKey = SecretKeySpec(key, "AES")
+        val ivSpec = IvParameterSpec(iv)
+        cipher.init(Cipher.DECRYPT_MODE, secretKey, ivSpec)
+        return cipher.doFinal(encryptedSegment)
+    }
+
     private suspend fun downloadHlsSource(context: Context, name: String, client: ManagedHttpClient, hlsUrl: String, targetFile: File, onProgress: (Long, Long, Long) -> Unit): Long {
         if(targetFile.exists())
             targetFile.delete();
@@ -579,6 +592,14 @@ class VideoDownload {
                 ?: throw Exception("Variant playlist content is empty")
 
             val variantPlaylist = HLS.parseVariantPlaylist(vpContent, hlsUrl)
+            val decryptionInfo: DecryptionInfo? = if (variantPlaylist.decryptionInfo != null) {
+                val keyResponse = client.get(variantPlaylist.decryptionInfo.keyUrl)
+                check(keyResponse.isOk) { "HLS request failed for decryption key: ${keyResponse.code}" }
+                DecryptionInfo(keyResponse.body!!.bytes(), variantPlaylist.decryptionInfo.iv.hexStringToByteArray())
+            } else {
+                null
+            }
+
             variantPlaylist.segments.forEachIndexed { index, segment ->
                 if (segment !is HLS.MediaSegment) {
                     return@forEachIndexed
@@ -590,7 +611,7 @@ class VideoDownload {
                 try {
                     segmentFiles.add(segmentFile)
 
-                    val segmentLength = downloadSource_Sequential(client, outputStream, segment.uri) { segmentLength, totalRead, lastSpeed ->
+                    val segmentLength = downloadSource_Sequential(client, outputStream, segment.uri, if (index == 0) null else decryptionInfo) { segmentLength, totalRead, lastSpeed ->
                         val averageSegmentLength = if (index == 0) segmentLength else downloadedTotalLength / index
                         val expectedTotalLength = averageSegmentLength * (variantPlaylist.segments.size - 1) + segmentLength
                         onProgress(expectedTotalLength, downloadedTotalLength + totalRead, lastSpeed)
@@ -771,7 +792,7 @@ class VideoDownload {
             else {
                 Logger.i(TAG, "Download $name Sequential");
                 try {
-                    sourceLength = downloadSource_Sequential(client, fileStream, videoUrl, onProgress);
+                    sourceLength = downloadSource_Sequential(client, fileStream, videoUrl, null, onProgress);
                 } catch (e: Throwable) {
                     Logger.w(TAG, "Failed to download sequentially (url = $videoUrl)")
                     throw e
@@ -798,7 +819,31 @@ class VideoDownload {
         }
         return sourceLength!!;
     }
-    private fun downloadSource_Sequential(client: ManagedHttpClient, fileStream: FileOutputStream, url: String, onProgress: (Long, Long, Long) -> Unit): Long {
+
+    data class DecryptionInfo(
+        val key: ByteArray,
+        val iv: ByteArray
+    ) {
+        override fun equals(other: Any?): Boolean {
+            if (this === other) return true
+            if (javaClass != other?.javaClass) return false
+
+            other as DecryptionInfo
+
+            if (!key.contentEquals(other.key)) return false
+            if (!iv.contentEquals(other.iv)) return false
+
+            return true
+        }
+
+        override fun hashCode(): Int {
+            var result = key.contentHashCode()
+            result = 31 * result + iv.contentHashCode()
+            return result
+        }
+    }
+
+    private fun downloadSource_Sequential(client: ManagedHttpClient, fileStream: FileOutputStream, url: String, decryptionInfo: DecryptionInfo?, onProgress: (Long, Long, Long) -> Unit): Long {
         val progressRate: Int = 4096 * 5;
         var lastProgressCount: Int = 0;
         val speedRate: Int = 4096 * 5;
@@ -818,6 +863,8 @@ class VideoDownload {
         val sourceLength = result.body.contentLength();
         val sourceStream = result.body.byteStream();
 
+        val segmentBuffer = ByteArrayOutputStream()
+
         var totalRead: Long = 0;
         try {
             var read: Int;
@@ -828,7 +875,7 @@ class VideoDownload {
                 if (read < 0)
                     break;
 
-                fileStream.write(buffer, 0, read);
+                segmentBuffer.write(buffer, 0, read);
 
                 totalRead += read;
 
@@ -854,6 +901,14 @@ class VideoDownload {
             result.body.close()
         }
 
+        if (decryptionInfo != null) {
+            val decryptedData =
+                decryptSegment(segmentBuffer.toByteArray(), decryptionInfo.key, decryptionInfo.iv)
+            fileStream.write(decryptedData)
+        } else {
+            fileStream.write(segmentBuffer.toByteArray())
+        }
+
         onProgress(sourceLength, totalRead, 0);
         return sourceLength;
     }

app/src/main/java/com/futo/platformplayer/parsers/HLS.kt

@@ -61,7 +61,27 @@ class HLS {
             val playlistType = lines.find { it.startsWith("#EXT-X-PLAYLIST-TYPE:") }?.substringAfter(":")
             val streamInfo = lines.find { it.startsWith("#EXT-X-STREAM-INF:") }?.let { parseStreamInfo(it) }
 
+            val keyInfo =
+                lines.find { it.startsWith("#EXT-X-KEY:") }?.substringAfter(":")?.split(",")
+
+            val key = keyInfo?.find { it.startsWith("URI=") }?.substringAfter("=")?.trim('"')
+            val iv =
+                keyInfo?.find { it.startsWith("IV=") }?.substringAfter("=")?.substringAfter("x")
+
+            val decryptionInfo: DecryptionInfo? = key?.let { k ->
+                iv?.let { i ->
+                    DecryptionInfo(k, i)
+                }
+            }
+
+            val initSegment =
+                lines.find { it.startsWith("#EXT-X-MAP:") }?.substringAfter(":")?.split(",")?.get(0)
+                    ?.substringAfter("=")?.trim('"')
             val segments = mutableListOf<Segment>()
+            if (initSegment != null) {
+                segments.add(MediaSegment(0.0, resolveUrl(sourceUrl, initSegment)))
+            }
+
             var currentSegment: MediaSegment? = null
             lines.forEach { line ->
                 when {
@@ -86,7 +106,7 @@ class HLS {
                 }
             }
 
-            return VariantPlaylist(version, targetDuration, mediaSequence, discontinuitySequence, programDateTime, playlistType, streamInfo, segments)
+            return VariantPlaylist(version, targetDuration, mediaSequence, discontinuitySequence, programDateTime, playlistType, streamInfo, segments, decryptionInfo)
         }
 
         fun parseAndGetVideoSources(source: Any, content: String, url: String): List<HLSVariantVideoUrlSource> {
@@ -368,6 +388,11 @@ class HLS {
         }
     }
 
+    data class DecryptionInfo(
+        val keyUrl: String,
+        val iv: String
+    )
+
     data class VariantPlaylist(
         val version: Int?,
         val targetDuration: Int?,
@@ -376,7 +401,8 @@ class HLS {
         val programDateTime: ZonedDateTime?,
         val playlistType: String?,
         val streamInfo: StreamInfo?,
-        val segments: List<Segment>
+        val segments: List<Segment>,
+        val decryptionInfo: DecryptionInfo? = null
     ) {
         fun buildM3U8(): String = buildString {
             append("#EXTM3U\n")