move gotd fork into repo. (#111)

- update to latest telegram layer
- remove some references to fields in tg.Entities that don't exist in
the schema
- originally added here:
https://github.com/beeper/td/commit/820929062a2ba0104397bc01235ab58a9cff780e
  - referenced here
-
https://github.com/mautrix/telegramgo/commit/124f0967ed195b5a380c9bd02e170ada9710dde3
-
https://github.com/mautrix/telegramgo/commit/4205047aab2e0639217148b5d125bfaab668bd8e

pkg/gotd/telegram/downloader/verifier_test.go

@@ -0,0 +1,104 @@
+package downloader
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"go.mau.fi/mautrix-telegram/pkg/gotd/tg"
+)
+
+var hashRanges = [][]tg.FileHash{
+	{
+		tg.FileHash{Offset: 0, Limit: 131072},
+		tg.FileHash{Offset: 131072, Limit: 131072},
+		tg.FileHash{Offset: 262144, Limit: 131072},
+		tg.FileHash{Offset: 393216, Limit: 131072},
+		tg.FileHash{Offset: 524288, Limit: 131072},
+		tg.FileHash{Offset: 655360, Limit: 131072},
+		tg.FileHash{Offset: 786432, Limit: 131072},
+		tg.FileHash{Offset: 917504, Limit: 131072},
+	}, {
+		tg.FileHash{Offset: 1048576, Limit: 131072},
+		tg.FileHash{Offset: 1179648, Limit: 131072},
+		tg.FileHash{Offset: 1310720, Limit: 131072},
+		tg.FileHash{Offset: 1441792, Limit: 131072},
+		tg.FileHash{Offset: 1572864, Limit: 131072},
+		tg.FileHash{Offset: 1703936, Limit: 131072},
+		tg.FileHash{Offset: 1835008, Limit: 131072},
+		tg.FileHash{Offset: 1966080, Limit: 131072},
+	}, {
+		tg.FileHash{Offset: 2097152, Limit: 131072},
+		tg.FileHash{Offset: 2228224, Limit: 131072},
+		tg.FileHash{Offset: 2359296, Limit: 131072},
+		tg.FileHash{Offset: 2490368, Limit: 131072},
+		tg.FileHash{Offset: 2621440, Limit: 131072},
+		tg.FileHash{Offset: 2752512, Limit: 131072},
+		tg.FileHash{Offset: 2883584, Limit: 131072},
+		tg.FileHash{Offset: 3014656, Limit: 131072},
+	},
+}
+
+type mockHashes struct {
+	ranges [][]tg.FileHash
+}
+
+func (m mockHashes) Chunk(ctx context.Context, offset int64, limit int) (chunk, error) {
+	panic("implement me")
+}
+
+func (m mockHashes) Hashes(ctx context.Context, offset int64) ([]tg.FileHash, error) {
+	for _, r := range m.ranges {
+		last := r[len(r)-1]
+		if last.Offset+int64(last.Limit) <= offset {
+			continue
+		}
+		return r, nil
+	}
+
+	return m.ranges[len(m.ranges)-1], nil
+}
+
+func TestVerifier(t *testing.T) {
+	ctx := context.Background()
+
+	tests := []struct {
+		name   string
+		ranges [][]tg.FileHash
+		// Hashes returned from CDN redirect, for example.
+		predefined []tg.FileHash
+		expected   [][]tg.FileHash
+	}{
+		{"NoPredefined", hashRanges, nil, hashRanges},
+		{"Predefined", hashRanges[1:], hashRanges[0], hashRanges},
+		{"OnlyPredefined", hashRanges[:1], hashRanges[0], hashRanges[:1]},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			a := require.New(t)
+			m := mockHashes{ranges: test.ranges}
+			v := newVerifier(m, test.predefined...)
+
+			hashes := make([]tg.FileHash, 0, len(test.predefined))
+			for {
+				hash, ok, err := v.next(ctx)
+				a.NoError(err)
+				if !ok {
+					break
+				}
+
+				hashes = append(hashes, hash)
+			}
+
+			i := 0
+			for _, hashRange := range test.expected {
+				for _, expected := range hashRange {
+					a.Equal(expected, hashes[i])
+					i++
+				}
+			}
+		})
+	}
+}