nil dereference panics prevention

[artemseleznev]

Hi! I should've fix other branches in my previous PR, but better late than never :)

[cpuschma]

This would satisfy your scanner, but would result in a faulty message due to the controlValue not having the necesarry fields for encoding the message.

ldap/v3/control.go

Lines 948 to 979 in 82fef14

	func (c *ControlServerSideSorting) Encode() *ber.Packet {
	packet := ber.Encode(ber.ClassUniversal, ber.TypeConstructed, ber.TagSequence, nil, "Control")
	control := ber.NewString(ber.ClassUniversal, ber.TypePrimitive, ber.TagOctetString, c.GetControlType(), "Control Type")
	value := ber.Encode(ber.ClassUniversal, ber.TypePrimitive, ber.TagOctetString, nil, "Control Value")
	seqs := ber.Encode(ber.ClassUniversal, ber.TypeConstructed, ber.TagSequence, nil, "SortKeyList")
	for _, f := range c.SortKeys {
	seq := ber.Encode(ber.ClassUniversal, ber.TypeConstructed, ber.TagSequence, nil, "")
	seq.AppendChild(
	ber.NewString(ber.ClassUniversal, ber.TypePrimitive, ber.TagOctetString, f.AttributeType, "attributeType"),
	)
	seq.AppendChild(
	ber.NewString(ber.ClassContext, ber.TypePrimitive, 0, f.MatchingRule, "orderingRule"),
	)
	if f.Reverse {
	seq.AppendChild(
	ber.NewBoolean(ber.ClassContext, ber.TypePrimitive, 1, f.Reverse, "reverseOrder"),
	)
	}
	seqs.AppendChild(seq)
	}
	value.AppendChild(seqs)
	packet.AppendChild(control)
	packet.AppendChild(value)
	return packet
	}

I suggest to disregard this particular change. The function is never called from a message processor but only by a developer.

[artemseleznev]

@cpuschma thank you for your feedback!
Yes, I fix this because the scanner marked this code, but I also prefer not to get panics in my project:-)

Please let me know if my fixes are excess, or some of them (not only in NewControlServerSideSorting)