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/mtproto/msg_seq_test.go

@@ -0,0 +1,104 @@
+package mtproto
+
+import (
+	"context"
+	"sync"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"go.mau.fi/mautrix-telegram/pkg/gotd/bin"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/tg"
+)
+
+func TestMsgSeq(t *testing.T) {
+	type record struct {
+		msgID int64
+		seqNo int32
+	}
+
+	var (
+		records []record
+		mux     sync.Mutex
+	)
+
+	const (
+		workers           = 32
+		requestsPerWorker = 200
+	)
+	client := newTestClient(func(msgID int64, seqNo int32, body bin.Encoder) (bin.Encoder, error) {
+		mux.Lock()
+		records = append(records, record{msgID, seqNo})
+		mux.Unlock()
+		return &tg.Config{}, nil
+	})
+
+	{
+		var wg sync.WaitGroup
+		wg.Add(workers)
+		for i := 0; i < workers; i++ {
+			go func(t *testing.T) {
+				defer wg.Done()
+
+				for i := 0; i < requestsPerWorker; i++ {
+					err := client.Invoke(context.Background(), &tg.Config{}, &tg.Config{})
+					require.NoError(t, err)
+				}
+			}(t)
+		}
+
+		wg.Wait()
+	}
+
+	var received []record
+	less := func(msgID int64, f func(r record)) {
+		for _, recv := range received {
+			if recv.msgID < msgID {
+				f(recv)
+			}
+		}
+	}
+
+	greater := func(msgID int64, f func(r record)) {
+		for _, recv := range received {
+			if recv.msgID > msgID {
+				f(recv)
+			}
+		}
+	}
+
+	contains := func(msgID int64) bool {
+		for _, rec := range received {
+			if rec.msgID == msgID {
+				return true
+			}
+		}
+
+		return false
+	}
+
+	for _, current := range records {
+		if contains(current.msgID) {
+			// Ignore duplicates.
+			continue
+		}
+
+		less(current.msgID, func(less record) {
+			// The server has already received a message with a lower msg_id
+			// but with either a higher or an equal and odd seqno.
+			if less.seqNo >= current.seqNo && less.seqNo%2 == 1 {
+				t.Fatal("seqNo too low")
+			}
+		})
+
+		greater(current.msgID, func(greater record) {
+			// Similarly, there is a message with a higher msg_id
+			// but with either a lower or an equal and odd seqno.
+			if greater.seqNo <= current.seqNo && greater.seqNo%2 == 1 {
+				t.Fatal("seqNo too high")
+			}
+		})
+
+		received = append(received, current)
+	}
+}