WebDAV: allow other MIME types for (Ranged) GET, use coroutines for streaming (#503)

* StreamingFileDescriptor: use coroutines instead of threading

* WebDAV GET: accept any MIME type, but prefer known one

app/src/main/kotlin/at/bitfire/davdroid/util/DavUtils.kt

@@ -13,9 +13,16 @@ import at.bitfire.davdroid.network.Android10Resolver
 import okhttp3.HttpUrl
 import okhttp3.MediaType
 import okhttp3.MediaType.Companion.toMediaType
-import org.xbill.DNS.*
+import org.xbill.DNS.ExtendedResolver
+import org.xbill.DNS.Lookup
+import org.xbill.DNS.Record
+import org.xbill.DNS.SRVRecord
+import org.xbill.DNS.SimpleResolver
+import org.xbill.DNS.TXTRecord
 import java.net.InetAddress
-import java.util.*
+import java.util.LinkedList
+import java.util.Locale
+import java.util.TreeMap
 
 /**
  * Some WebDAV and HTTP network utility methods.
@@ -30,6 +37,19 @@ object DavUtils {
     val MEDIA_TYPE_OCTET_STREAM = "application/octet-stream".toMediaType()
     val MEDIA_TYPE_VCARD = "text/vcard".toMediaType()
 
+    /**
+     * Builds an HTTP `Accept` header that accepts anything (*/*), but optionally
+     * specifies a preference.
+     *
+     * @param preferred  preferred MIME type (optional)
+     *
+     * @return `media-range` for `Accept` header that accepts anything, but prefers [preferred] (if it was specified)
+     */
+    fun acceptAnything(preferred: MediaType?): String =
+        if (preferred != null)
+            "$preferred, $MIME_TYPE_ACCEPT_ALL;q=0.8"
+        else
+            MIME_TYPE_ACCEPT_ALL
 
     @Suppress("FunctionName")
     fun ARGBtoCalDAVColor(colorWithAlpha: Int): String {

app/src/main/kotlin/at/bitfire/davdroid/webdav/RandomAccessCallback.kt

@@ -167,7 +167,7 @@ class RandomAccessCallback private constructor(
 
         var result: ByteArray? = null
         dav.getRange(
-            mimeType?.toString() ?: DavUtils.MIME_TYPE_ACCEPT_ALL,
+            DavUtils.acceptAnything(preferred = mimeType),
             key.segment * PAGE_SIZE.toLong(),
             PAGE_SIZE,
             ifMatch

app/src/main/kotlin/at/bitfire/davdroid/webdav/StreamingFileDescriptor.kt

@@ -12,12 +12,16 @@ import androidx.core.app.NotificationCompat
 import androidx.core.app.NotificationManagerCompat
 import at.bitfire.dav4jvm.DavResource
 import at.bitfire.dav4jvm.exception.HttpException
-import at.bitfire.davdroid.network.HttpClient
 import at.bitfire.davdroid.R
 import at.bitfire.davdroid.log.Logger
+import at.bitfire.davdroid.network.HttpClient
 import at.bitfire.davdroid.ui.NotificationUtils
 import at.bitfire.davdroid.ui.NotificationUtils.notifyIfPossible
 import at.bitfire.davdroid.util.DavUtils
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.async
+import kotlinx.coroutines.runInterruptible
 import okhttp3.HttpUrl
 import okhttp3.MediaType
 import okhttp3.RequestBody
@@ -26,7 +30,6 @@ import okio.BufferedSink
 import org.apache.commons.io.FileUtils
 import java.io.IOException
 import java.util.logging.Level
-import kotlin.concurrent.thread
 
 /**
  * @param client    HTTP client– [StreamingFileDescriptor] is responsible to close it
@@ -64,7 +67,7 @@ class StreamingFileDescriptor(
     private fun doStreaming(upload: Boolean): ParcelFileDescriptor {
         val (readFd, writeFd) = ParcelFileDescriptor.createReliablePipe()
 
-        val worker = thread {
+        val result = CoroutineScope(Dispatchers.IO).async {
             try {
                 if (upload)
                     uploadNow(readFd)
@@ -92,7 +95,7 @@ class StreamingFileDescriptor(
 
         cancellationSignal?.setOnCancelListener {
             Logger.log.fine("Cancelling transfer of $url")
-            worker.interrupt()
+            result.cancel()
         }
 
         return if (upload)
@@ -102,8 +105,8 @@ class StreamingFileDescriptor(
     }
 
     @WorkerThread
-    private fun downloadNow(writeFd: ParcelFileDescriptor) {
-        dav.get(mimeType?.toString() ?: DavUtils.MIME_TYPE_ACCEPT_ALL, null) { response ->
+    private suspend fun downloadNow(writeFd: ParcelFileDescriptor) = runInterruptible {
+        dav.get(DavUtils.acceptAnything(preferred = mimeType), null) { response ->
             response.body?.use { body ->
                 if (response.isSuccessful) {
                     val length = response.headersContentLength()
@@ -156,7 +159,7 @@ class StreamingFileDescriptor(
     }
 
     @WorkerThread
-    private fun uploadNow(readFd: ParcelFileDescriptor) {
+    private suspend fun uploadNow(readFd: ParcelFileDescriptor) = runInterruptible {
         val body = object: RequestBody() {
             override fun contentType(): MediaType? = mimeType
             override fun isOneShot() = true

app/src/test/kotlin/at/bitfire/davdroid/DavUtilsTest.kt

@@ -7,6 +7,7 @@ package at.bitfire.davdroid
 import at.bitfire.davdroid.util.DavUtils
 import at.bitfire.davdroid.util.DavUtils.parent
 import okhttp3.HttpUrl.Companion.toHttpUrl
+import okhttp3.MediaType.Companion.toMediaType
 import org.junit.Assert.assertEquals
 import org.junit.Assert.assertNull
 import org.junit.Assert.assertTrue
@@ -19,6 +20,13 @@ class DavUtilsTest {
 
     val exampleURL = "http://example.com/"
 
+
+    @Test
+    fun testAcceptAnything() {
+        assertEquals("*/*", DavUtils.acceptAnything(null))
+        assertEquals("some/thing;v=2.1, */*;q=0.8", DavUtils.acceptAnything("some/thing;v=2.1".toMediaType()))
+    }
+
     @Test
     fun testARGBtoCalDAVColor() {
         assertEquals("#00000000", DavUtils.ARGBtoCalDAVColor(0))