[PATCH libnetfilter_queue 2/2] pktbuff: add pktb_head_alloc(), pktb_setup() and pktb_head_size()

[Pablo Neira Ayuso <pablo@netfilter.org>]

Add two new helper functions, as alternative to pktb_alloc().

* pktb_setup() allows you to skip memcpy()'ing the payload from the
  netlink message.

* pktb_head_size() returns the size of the pkt_buff opaque object.

* pktb_head_alloc() allows you to allocate the pkt_buff in the heap.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 include/libnetfilter_queue/pktbuff.h |  7 +++++++
 src/extra/pktbuff.c                  | 20 ++++++++++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/include/libnetfilter_queue/pktbuff.h b/include/libnetfilter_queue/pktbuff.h
index 42bc153ec337..a27582b02840 100644
--- a/include/libnetfilter_queue/pktbuff.h
+++ b/include/libnetfilter_queue/pktbuff.h
@@ -6,6 +6,13 @@ 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);
 
+#define NFQ_BUFFER_SIZE	(0xffff + (MNL_SOCKET_BUFFER_SIZE / 2)
+struct pkt_buff *pktb_setup(struct pkt_buff *pktb, int family, uint8_t *data,
+			    size_t len, size_t extra);
+size_t pktb_head_size(void);
+
+#define pktb_head_alloc()	(struct pkt_buff *)(malloc(pktb_head_size()))
+
 uint8_t *pktb_data(struct pkt_buff *pktb);
 uint32_t pktb_len(struct pkt_buff *pktb);
 
diff --git a/src/extra/pktbuff.c b/src/extra/pktbuff.c
index 118ad898f63b..6acefbe72a9b 100644
--- a/src/extra/pktbuff.c
+++ b/src/extra/pktbuff.c
@@ -103,6 +103,26 @@ struct pkt_buff *pktb_alloc(int family, void *data, size_t len, size_t extra)
 	return pktb;
 }
 
+EXPORT_SYMBOL
+struct pkt_buff *pktb_setup(struct pkt_buff *pktb, int family, uint8_t *buf,
+			    size_t len, size_t extra)
+{
+	pktb->data_len = len + extra;
+	pktb->data = buf;
+	pktb->len = len;
+
+	if (__pktb_setup(family, pktb) < 0)
+		return NULL;
+
+	return pktb;
+}
+
+EXPORT_SYMBOL
+size_t pktb_head_size(void)
+{
+	return sizeof(struct pkt_buff);
+}
+
 /**
  * pktb_data - get pointer to network packet
  * \param pktb Pointer to userspace packet buffer
-- 
2.20.1