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/proto/codec/abridged_test.go

@@ -0,0 +1,69 @@
+package codec
+
+import (
+	"bytes"
+	"encoding/binary"
+	"strings"
+	"testing"
+
+	"go.mau.fi/mautrix-telegram/pkg/gotd/bin"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestAbridged(t *testing.T) {
+	bigHeader := func(l int) (packet []byte) {
+		// header + 3 bytes of LE
+		var buf [4]byte
+		binary.LittleEndian.PutUint32(buf[:], uint32(l>>2))
+
+		packet = append([]byte{127}, buf[0:3]...)
+		return
+	}
+
+	tests := []struct {
+		payloadName string
+		testData    func() (payload string, packet []byte)
+	}{
+		{"Small-4b", func() (payload string, packet []byte) {
+			payload = "abcd"
+			packet = append([]byte{byte(len(payload) >> 2)}, payload...)
+			return
+		}},
+
+		{"Medium-124b", func() (payload string, packet []byte) {
+			payload = strings.Repeat("a", 124)
+			packet = append([]byte{byte(len(payload) >> 2)}, payload...)
+			return
+		}},
+
+		{"Big-1kb", func() (payload string, packet []byte) {
+			payload = strings.Repeat("a", 1024)
+			packet = bigHeader(len(payload))
+			require.Equal(t, []byte{127, 0, 1, 0}, packet)
+			packet = append(packet, payload...)
+			return
+		}},
+	}
+
+	for _, test := range tests {
+		payload, packet := test.testData()
+		t.Run(test.payloadName, func(t *testing.T) {
+			t.Run("Write", func(t *testing.T) {
+				b := bytes.NewBuffer(nil)
+				err := writeAbridged(b, &bin.Buffer{Buf: []byte(payload)})
+				require.NoError(t, err)
+
+				require.Equal(t, packet, b.Bytes())
+			})
+
+			t.Run("Read", func(t *testing.T) {
+				b := &bin.Buffer{}
+				err := readAbridged(bytes.NewReader(packet), b)
+				require.NoError(t, err)
+
+				require.Equal(t, payload, string(b.Raw()))
+			})
+		})
+	}
+}