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/crypto/check_dh_test.go

@@ -0,0 +1,42 @@
+package crypto
+
+import (
+	"math/big"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func BenchmarkCheckDH(b *testing.B) {
+	b.ReportAllocs()
+	b.ResetTimer()
+
+	for i := 0; i < b.N; i++ {
+		_ = CheckDH(checkGPg, checkGPdhPrime)
+	}
+}
+
+func TestCheckDH(t *testing.T) {
+	t.Run("OK", func(t *testing.T) {
+		a := require.New(t)
+		a.NoError(CheckDH(checkGPg, checkGPdhPrime))
+	})
+	t.Run("WrongG", func(t *testing.T) {
+		require.Error(t, CheckDH(1337, checkGPdhPrime))
+	})
+	t.Run("TooSmallBits", func(t *testing.T) {
+		require.Error(t, CheckDH(3, big.NewInt(4)))
+	})
+}
+
+func Test_checkPrime(t *testing.T) {
+	t.Run("OK", func(t *testing.T) {
+		require.NoError(t, checkPrime(big.NewInt(5)))
+	})
+	t.Run("PNotPrime", func(t *testing.T) {
+		require.Error(t, checkPrime(big.NewInt(4)))
+	})
+	t.Run("HalfPMinusOneNotPrime", func(t *testing.T) {
+		require.Error(t, checkPrime(big.NewInt(13)))
+	})
+}