src: add alternative API to set up packet buffer

pktb_setup_raw() is a new function to initialise a new struct pkt_buff.
It takes the memory area to be used to store pkt_buff structure and the
data. Data is attached to the packet buffer (not copied), ie. the packet
buffer data points to the provided data pointer.

pktb_head_size() is a new function to return the amount of memory to
reserve for a new struct pkt_buff.

Extend documentation pon pktb_alloc().

Mostly original patch from Duncan Roe <duncan_roe@optusnet.com.au>.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/libnetfilter_queue/pktbuff.h b/include/libnetfilter_queue/pktbuff.h
index 42bc153..a4cc2a1 100644
--- a/include/libnetfilter_queue/pktbuff.h
+++ b/include/libnetfilter_queue/pktbuff.h
@@ -6,6 +6,9 @@ struct pkt_buff;
 struct pkt_buff *pktb_alloc(int family, void *data, size_t len, size_t extra);
 void pktb_free(struct pkt_buff *pktb);
 
+struct pkt_buff *pktb_setup_raw(void *pktb, int family, void *data, size_t len, size_t extra);
+size_t pktb_head_size(void);
+
 uint8_t *pktb_data(struct pkt_buff *pktb);
 uint32_t pktb_len(struct pkt_buff *pktb);