Add fallback when WebDAV PROPFIND with depth=2 isn't supported

app/src/main/java/com/stevesoltys/seedvault/plugins/webdav/WebDavStorage.kt

@@ -8,7 +8,11 @@ package com.stevesoltys.seedvault.plugins.webdav
 import android.util.Log
 import at.bitfire.dav4jvm.BasicDigestAuthHandler
 import at.bitfire.dav4jvm.DavCollection
+import at.bitfire.dav4jvm.MultiResponseCallback
 import at.bitfire.dav4jvm.Response
+import at.bitfire.dav4jvm.Response.HrefRelation.SELF
+import at.bitfire.dav4jvm.exception.HttpException
+import at.bitfire.dav4jvm.property.DisplayName
 import at.bitfire.dav4jvm.property.ResourceType
 import kotlinx.coroutines.DelicateCoroutinesApi
 import kotlinx.coroutines.Dispatchers
@@ -124,6 +128,47 @@ internal abstract class WebDavStorage(
         return pipedInputStream
     }
 
+    /**
+     * Tries to do [DavCollection.propfind] with a depth of `2` which is not in RFC4918.
+     * Since `infinity` isn't supported by nginx either,
+     * we fallback to iterating over all folders found with depth `1`
+     * and do another PROPFIND on those, passing the given [callback].
+     */
+    protected fun DavCollection.propfindDepthTwo(callback: MultiResponseCallback) {
+        try {
+            propfind(
+                depth = 2, // this isn't defined in RFC4918
+                reqProp = arrayOf(DisplayName.NAME, ResourceType.NAME),
+                callback = callback,
+            )
+        } catch (e: HttpException) {
+            if (e.code == 400) {
+                Log.i(TAG, "Got ${e.response}, trying two depth=1 PROPFINDs...")
+                propfindFakeTwo(callback)
+            } else {
+                throw e
+            }
+        }
+    }
+
+    private fun DavCollection.propfindFakeTwo(callback: MultiResponseCallback) {
+        propfind(
+            depth = 1,
+            reqProp = arrayOf(DisplayName.NAME, ResourceType.NAME),
+        ) { response, relation ->
+            debugLog { "propFindFakeTwo() = $response" }
+            // This callback will be called for everything in the folder
+            callback.onResponse(response, relation)
+            if (relation != SELF && response.isFolder()) {
+                DavCollection(okHttpClient, response.href).propfind(
+                    depth = 1,
+                    reqProp = arrayOf(DisplayName.NAME, ResourceType.NAME),
+                    callback = callback,
+                )
+            }
+        }
+    }
+
     protected suspend fun DavCollection.createFolder(xmlBody: String? = null): okhttp3.Response {
         return try {
             suspendCoroutine { cont ->

app/src/main/java/com/stevesoltys/seedvault/plugins/webdav/WebDavStoragePlugin.kt

@@ -9,6 +9,7 @@ import android.content.Context
 import android.util.Log
 import at.bitfire.dav4jvm.DavCollection
 import at.bitfire.dav4jvm.Response.HrefRelation.SELF
+import at.bitfire.dav4jvm.exception.HttpException
 import at.bitfire.dav4jvm.exception.NotFoundException
 import at.bitfire.dav4jvm.property.DisplayName
 import at.bitfire.dav4jvm.property.QuotaAvailableBytes
@@ -174,6 +175,7 @@ internal class WebDavStoragePlugin(
 
         // get all restore set tokens in root folder
         val tokens = ArrayList<Long>()
+        try {
             davCollection.propfind(
                 depth = 2,
                 reqProp = arrayOf(DisplayName.NAME, ResourceType.NAME),
@@ -189,6 +191,10 @@ internal class WebDavStoragePlugin(
                     }
                 }
             }
+        } catch (e: HttpException) {
+            if (e.code == 400) getBackupTokenWithDepthOne(davCollection, tokens)
+            else throw e
+        }
         val tokenIterator = tokens.iterator()
         return generateSequence {
             if (!tokenIterator.hasNext()) return@generateSequence null // end sequence
@@ -199,6 +205,34 @@ internal class WebDavStoragePlugin(
         }
     }
 
+    private fun getBackupTokenWithDepthOne(davCollection: DavCollection, tokens: ArrayList<Long>) {
+        davCollection.propfind(
+            depth = 1,
+            reqProp = arrayOf(DisplayName.NAME, ResourceType.NAME),
+        ) { response, relation ->
+            debugLog { "getBackupTokenWithDepthOne() = $response" }
+
+            // we are only interested in sub-folders, skip rest
+            if (relation == SELF || !response.isFolder()) return@propfind
+
+            val token = getTokenOrNull(response.hrefName()) ?: return@propfind
+            val tokenUrl = response.href.newBuilder()
+                .addPathSegment(FILE_BACKUP_METADATA)
+                .build()
+            // check if .backup.metadata file exists using HEAD request,
+            // because some servers (e.g. nginx don't list hidden files with PROPFIND)
+            try {
+                DavCollection(okHttpClient, tokenUrl).head {
+                    debugLog { "getBackupTokenWithDepthOne() = $response" }
+                    tokens.add(token)
+                }
+            } catch (e: Exception) {
+                // just log exception and continue, we want to find all files that are there
+                Log.e(TAG, "Error retrieving $tokenUrl: ", e)
+            }
+        }
+    }
+
     private fun getTokenOrNull(name: String): Long? {
         val looksLikeToken = name.isNotEmpty() && tokenRegex.matches(name)
         if (looksLikeToken) {

app/src/main/java/com/stevesoltys/seedvault/storage/WebDavStoragePlugin.kt

@@ -77,10 +77,7 @@ internal class WebDavStoragePlugin(
         val chunkIds = ArrayList<String>()
         try {
             val duration = measureDuration {
-                davCollection.propfind(
+                davCollection.propfindDepthTwo { response, relation ->
-                    depth = 2,
-                    reqProp = arrayOf(DisplayName.NAME, ResourceType.NAME),
-                ) { response, relation ->
                     debugLog { "getAvailableChunkIds() = $response" }
                     // This callback will be called for every file in the folder
                     if (relation != SELF && response.isFolder()) {
@@ -162,13 +159,10 @@ internal class WebDavStoragePlugin(
 
         val snapshots = ArrayList<StoredSnapshot>()
         try {
-            davCollection.propfind(
+            davCollection.propfindDepthTwo { response, relation ->
-                depth = 2,
-                reqProp = arrayOf(DisplayName.NAME, ResourceType.NAME),
-            ) { response, relation ->
                 debugLog { "getBackupSnapshotsForRestore() = $response" }
                 // This callback will be called for every file in the folder
-                if (relation != SELF && !response.isFolder()) {
+                if (relation != SELF && !response.isFolder() && response.href.pathSize >= 2) {
                     val name = response.hrefName()
                     val match = snapshotRegex.matchEntire(name)
                     if (match != null) {

app/src/test/java/com/stevesoltys/seedvault/plugins/webdav/WebDavStoragePluginTest.kt

@@ -71,6 +71,10 @@ internal class WebDavStoragePluginTest : TransportTest() {
         plugin.getOutputStream(token, FILE_BACKUP_METADATA).use {
             it.write(metadata)
         }
+
+        // now we have data
+        assertTrue(plugin.hasData(token, FILE_BACKUP_METADATA))
+
         try {
             // now we have one backup matching our token
             val backups = plugin.getAvailableBackups()?.toSet() ?: fail()