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/transport/connection.go

@@ -0,0 +1,79 @@
+package transport
+
+import (
+	"context"
+	"net"
+	"sync"
+	"time"
+
+	"github.com/go-faster/errors"
+
+	"go.mau.fi/mautrix-telegram/pkg/gotd/bin"
+)
+
+// Conn is transport connection.
+type Conn interface {
+	Send(ctx context.Context, b *bin.Buffer) error
+	Recv(ctx context.Context, b *bin.Buffer) error
+	Close() error
+}
+
+var _ Conn = (*connection)(nil)
+
+// connection is MTProto connection.
+type connection struct {
+	conn  net.Conn
+	codec Codec
+
+	readMux  sync.Mutex
+	writeMux sync.Mutex
+}
+
+// Send sends message from buffer using MTProto connection.
+func (c *connection) Send(ctx context.Context, b *bin.Buffer) error {
+	// Serializing access to deadlines.
+	c.writeMux.Lock()
+	defer c.writeMux.Unlock()
+
+	if err := c.conn.SetWriteDeadline(time.Time{}); err != nil {
+		return errors.Wrap(err, "reset write deadline")
+	}
+	if deadline, ok := ctx.Deadline(); ok {
+		if err := c.conn.SetWriteDeadline(deadline); err != nil {
+			return errors.Wrap(err, "set write deadline")
+		}
+	}
+
+	if err := c.codec.Write(c.conn, b); err != nil {
+		return errors.Wrap(err, "write")
+	}
+
+	return nil
+}
+
+// Recv reads message to buffer using MTProto connection.
+func (c *connection) Recv(ctx context.Context, b *bin.Buffer) error {
+	// Serializing access to deadlines.
+	c.readMux.Lock()
+	defer c.readMux.Unlock()
+
+	if err := c.conn.SetReadDeadline(time.Time{}); err != nil {
+		return errors.Wrap(err, "reset read deadline")
+	}
+	if deadline, ok := ctx.Deadline(); ok {
+		if err := c.conn.SetReadDeadline(deadline); err != nil {
+			return errors.Wrap(err, "set read deadline")
+		}
+	}
+
+	if err := c.codec.Read(c.conn, b); err != nil {
+		return errors.Wrap(err, "read")
+	}
+
+	return nil
+}
+
+// Close closes MTProto connection.
+func (c *connection) Close() error {
+	return c.conn.Close()
+}