Network Security Tools

Context Queues

If you want to send multiple packets, possibly through different interfaces, you have a couple of options. You can handle each libnet context and send the packet individually, or you can use context queues to create a series of packets, and send them out in an organized fashion.

Context queues are a very useful mechanism for handling multiple-context situations. It is easy to create a context queue: just push a context onto the queue using libnet_cq_add( ) as follows:

int libnet_cq_add (libnet_t *l, char *label)

This function returns 1 on success and -1 on failure, with libnet_geterror() telling you why. Each context and identifier label must be unique, as they are identifiers for returning libnet contexts from the queue using libnet_cq_find_by_label() as follows:

libnet_t* libnet_cq_find_by_label (char *label)

To look up labels for contexts on the queue, use libnet_cq_getlabel( ) as follows:

int8_t* libnet_cq_getlabel (libnet_t *l)

Contexts can be iterated using libnet_cq_head( ) to return the first item in the queue and prevent additional items from being added to the queue; libnet_cq_next() to return the next item in the queue; libnet_cq_last() to see if the context is the last in the queue; or libnet_cq_size() to track the queue size. Do this manually as follows:

libnet_t* l;
for (l = libnet_cq_head( ); libnet_cq_last( ); l = libnet_cq_next( ))
{
   ...
}

Or you can do this using the provided for_each_context_in_cq() macro.

You can remove contexts from the queue either ...