Chain elements should always pass Close down the chain about sdk

[d-uzlov]

List of elements that could cancel Close

This is the list of elements in sdk repo.
I haven't checked other repos.

Open me

• authorize/client:

  sdk/pkg/networkservice/common/authorize/client.go

  Lines 105 to 109 in 63043b2

  	if err := a.policies.check(ctx, conn.GetPath()); err != nil {
  	return nil, err
  	}
  	return next.Client(ctx).Close(ctx, conn, opts...)

• authorize/server:

  sdk/pkg/networkservice/common/authorize/server.go

  Lines 126 to 130 in 63043b2

  	if err := a.policies.check(ctx, leftSide); err != nil {
  	return nil, err
  	}
  	}
  	return next.Server(ctx).Close(ctx, conn)

• begin/client
• begin/server
• discover/server
• discoverForwarder/server
• recvfd/server:

  sdk/pkg/networkservice/common/mechanisms/recvfd/server.go

  Lines 99 to 104 in 63043b2

  	if err != nil {
  	return nil, err
  	}
  	// Call the next server in the chain
  	_, err = next.Server(ctx).Close(ctx, conn)

• sendfd/client:

  sdk/pkg/networkservice/common/mechanisms/sendfd/client.go

  Lines 77 to 82 in 63043b2

  	if err := sendFDAndSwapFileToInode(sender, conn.GetMechanism().GetParameters(), inodeURLToFileURLMap); err != nil {
  	return nil, err
  	}
  	// Call the next Client in the chain
  	_, err := next.Client(ctx).Close(ctx, conn, opts...)

• mechanisms/client:

  sdk/pkg/networkservice/common/mechanisms/client.go

  Line 75 in 63043b2

  return nil, errCannotSupportMech

• mechanisms/server:

  sdk/pkg/networkservice/common/mechanisms/server.go

  Line 86 in 63043b2

  return nil, errCannotSupportMech

• updatepath/client
• updatepath/server
• updatetoken/server:

  sdk/pkg/networkservice/common/updatetoken/server.go

  Lines 81 to 84 in 63043b2

  	if err != nil {
  	return nil, err
  	}
  	return next.Server(ctx).Close(ctx, conn)

Some of these elements are fine.
For example, it is reasonable to expect begin to drop closes for unknown connections.
I'm not sure about authorize, updatepath, updatetoken elements, maybe they are also fine.

discover and discoverForwarder will be fixed in #1454.

mechanisms/client and mechanisms/server look semi-fine, because they will only fail if we try to Close with connection with invalid Connection.Mechanism.

recvfd/server and sendfd/client look concerning to me.