From 22e09334ec8251f303ebde9292e46fb5a25c5a19 Mon Sep 17 00:00:00 2001
From: Simon Frei <freisim93@gmail.com>
Date: Sat, 22 May 2021 21:38:49 +0200
Subject: lib/model: Fix incoming request on receive-enc (fixes #7699) (#7702)

---
 lib/model/model.go         |  2 +-
 lib/model/requests_test.go | 32 ++++++++++++++++++++++++++++++--
 2 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/lib/model/model.go b/lib/model/model.go
index e8b4fec3e6..94b5d596b6 100644
--- a/lib/model/model.go
+++ b/lib/model/model.go
@@ -1941,7 +1941,7 @@ func (m *model) Request(deviceID protocol.DeviceID, folder, name string, blockNo
 		return nil, protocol.ErrGeneric
 	}
 
-	if len(hash) > 0 && !scanner.Validate(res.data[:n], hash, weakHash) {
+	if folderCfg.Type != config.FolderTypeReceiveEncrypted && len(hash) > 0 && !scanner.Validate(res.data[:n], hash, weakHash) {
 		m.recheckFile(deviceID, folder, name, offset, hash, weakHash)
 		l.Debugf("%v REQ(in) failed validating data: %s: %q / %q o=%d s=%d", m, deviceID, folder, name, offset, size)
 		return nil, protocol.ErrNoSuchFile
diff --git a/lib/model/requests_test.go b/lib/model/requests_test.go
index c604997b0b..da3e8d0361 100644
--- a/lib/model/requests_test.go
+++ b/lib/model/requests_test.go
@@ -24,6 +24,7 @@ import (
 	"github.com/syncthing/syncthing/lib/events"
 	"github.com/syncthing/syncthing/lib/fs"
 	"github.com/syncthing/syncthing/lib/protocol"
+	"github.com/syncthing/syncthing/lib/rand"
 )
 
 func TestRequestSimple(t *testing.T) {
@@ -1339,7 +1340,7 @@ func TestRequestIndexSenderClusterConfigBeforeStart(t *testing.T) {
 	}
 }
 
-func TestRequestReceiveEncryptedLocalNoSend(t *testing.T) {
+func TestRequestReceiveEncrypted(t *testing.T) {
 	if testing.Short() {
 		t.Skip("skipping on short testing - scrypt is too slow")
 	}
@@ -1364,10 +1365,11 @@ func TestRequestReceiveEncryptedLocalNoSend(t *testing.T) {
 	m.fmut.RUnlock()
 	fset.Update(protocol.LocalDeviceID, files)
 
-	indexChan := make(chan []protocol.FileInfo, 1)
+	indexChan := make(chan []protocol.FileInfo, 10)
 	done := make(chan struct{})
 	defer close(done)
 	fc := newFakeConnection(device1, m)
+	fc.folder = fcfg.ID
 	fc.setIndexFn(func(_ context.Context, _ string, fs []protocol.FileInfo) error {
 		select {
 		case indexChan <- fs:
@@ -1402,6 +1404,32 @@ func TestRequestReceiveEncryptedLocalNoSend(t *testing.T) {
 	case <-time.After(5 * time.Second):
 		t.Fatal("timed out before receiving index")
 	}
+
+	// Detects deletion, as we never really created the file on disk
+	// Shouldn't send anything because receive-encrypted
+	must(t, m.ScanFolder(fcfg.ID))
+	// One real file to be sent
+	name := "foo"
+	data := make([]byte, 2000)
+	rand.Read(data)
+	fc.addFile(name, 0664, protocol.FileInfoTypeFile, data)
+	fc.sendIndexUpdate()
+
+	select {
+	case fs := <-indexChan:
+		if len(fs) != 1 {
+			t.Error("Expected index with one file, got", fs)
+		}
+		if got := fs[0].Name; got != name {
+			t.Errorf("Expected file %v, got %v", got, files[0].Name)
+		}
+	case <-time.After(5 * time.Second):
+		t.Fatal("timed out before receiving index")
+	}
+
+	// Simulate request from device that is untrusted too, i.e. with non-empty, but garbage hash
+	_, err := m.Request(device1, fcfg.ID, name, 0, 1064, 0, []byte("garbage"), 0, false)
+	must(t, err)
 }
 
 func TestRequestGlobalInvalidToValid(t *testing.T) {
-- 
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