Re: [ns] variable length packet header

[Ratul Mahajan <ratul@aciri.org>]

You can just put in a pointer in the header to a dynamically allocated
structure.

	-ratul

On Tue, 31 Oct 2000, Jan Cerlot wrote:

> Hi,
> 
> I've created a new header to acknowledge received messages at one node. This 
> node sends acknowledge packets every x ms. The problem is that, in this period 
> of time, this node can receive 1 but also ... 1000 messages to acknowledge. 
> Therefore I would like not to have a fixed array with the length 1000 that would 
> be often unused but a dynamic array whose length would grow with the number of 
> messages to acknowldege. 
> 
> So now, I have something like that :
> 
> in <rack.h> :
> 
> struct hdr_rack {
> 	
> 	int sess_id_[1000]; 
> 		
> 	static int offset_;
> 	inline static int& offset() { return offset_; }
> 	inline static hdr_rack* access(Packet* p) {
> 		return (hdr_rack*) p->access(offset_);
> 	}
> 
> 	int& sess_id(int i) {return sess_id_[i];}
> };
> 
> and in <rack.cc> :
> 
> int hdr_rack::offset_;
> 
> static class RackHeaderClass : public PacketHeaderClass {
> public:
> 	RackHeaderClass() : PacketHeaderClass("PacketHeader/Rack",
> 					      sizeof(hdr_rack)) {
> 		bind_offset(&hdr_rack::offset_);
> 	}
> 	void export_offsets() {
> 		field_offset("sess_id_", OFFSET(hdr_rack, sess_id_));
> 	}
> } class_rackhdr;
> 
> What do I need to change to have this sess_id_ array dynamic ??
> 
> Thanks a lot for your answers
> 
>       Jan.
> 
>