@@ -4,6 +4,8 @@
struct pkt_buff;
struct pkt_buff *pktb_alloc(int family, void *data, size_t len, size_t extra);
+struct pkt_buff *pktb_usebuf(int family, void *data, size_t len, size_t extra,
+ void *buf, size_t bufsize);
void pktb_free(struct pkt_buff *pktb);
uint8_t *pktb_data(struct pkt_buff *pktb);
@@ -96,6 +96,88 @@ struct pkt_buff *pktb_alloc(int family, void *data, size_t len, size_t extra)
return pktb;
}
+/**
+ * pktb_usebuf - make a packet buffer from an existing buffer
+ * \param family Indicate what family. Currently supported families are
+ * AF_BRIDGE, AF_INET & AF_INET6.
+ * \param data Pointer to packet data
+ * \param len Packet length
+ * \param extra Extra memory in the tail to be allocated (for mangling)
+ * \param buf Existing buffer to use
+ * \param bufsize Size of _buf_
+ *
+ * This function builds a userspace packet buffer inside a supplied buffer.
+ * The packet buffer contains the packet data and some extra memory room in the
+ * tail (if requested).
+ *
+ * This function uses less CPU cycles than pktb_alloc() + pktb_free().
+ * Users can expect a decrease in overall CPU time in the order of 5%.
+ *
+ * \return Pointer to a userspace packet buffer aligned within _buf_ or NULL on
+ * failure.
+ * \par Errors
+ * __ENOMEM__ _bufsize_ is too small to accomodate _len_
+ * \n
+ * __EPROTONOSUPPORT__ _family_ was __AF_BRIDGE__ and this is not an IP packet
+ * (v4 or v6)
+ * \warning Do __not__ call pktb_free() on the returned pointer
+ */
+EXPORT_SYMBOL
+struct pkt_buff *pktb_usebuf(int family, void *data, size_t len, size_t extra,
+ void *buf, size_t bufsize)
+{
+ struct pkt_buff *pktb;
+ void *pkt_data;
+
+ /* Better make sure alignment is correct. */
+ size_t extra2 =
+ (size_t)buf & 0x7 ? (~((size_t)buf & 0x7) & 0x7) + 1 : 0;
+
+ pktb = buf + extra2;
+ if (extra2 + sizeof(struct pkt_buff) + len + extra > bufsize)
+ {
+ errno = ENOMEM;
+ return NULL;
+ }
+ memset(pktb, 0, sizeof(struct pkt_buff) + len + extra);
+
+ pkt_data = (uint8_t *)pktb + sizeof(struct pkt_buff);
+ memcpy(pkt_data, data, len);
+
+ pktb->len = len;
+ pktb->data_len = len + extra;
+
+ pktb->head = pkt_data;
+ pktb->data = pkt_data;
+ pktb->tail = pktb->head + len;
+
+ switch(family) {
+ case AF_INET:
+ case AF_INET6:
+ pktb->network_header = pktb->data;
+ break;
+ case AF_BRIDGE: {
+ struct ethhdr *ethhdr = (struct ethhdr *)pktb->data;
+
+ pktb->mac_header = pktb->data;
+
+ switch(ethhdr->h_proto) {
+ case ETH_P_IP:
+ case ETH_P_IPV6:
+ pktb->network_header = pktb->data + ETH_HLEN;
+ break;
+ default:
+ /* This protocol is unsupported. */
+ errno = EPROTONOSUPPORT;
+ free(pktb);
+ return NULL;
+ }
+ break;
+ }
+ }
+ return pktb;
+}
+
/**
* pktb_data - get pointer to network packet
* \param pktb Pointer to userspace packet buffer
New function pktb_usebuf() works like pktb_alloc() except it has 2 extra arguments, being a user-supplied buffer and its length. Performance testing is ongoing, so the 5% improvement claimed in the documentation is conservative. Updated: include/libnetfilter_queue/pktbuff.h: Add pktb_usebuf() prototype src/extra/pktbuff.c: Implement pktb_usebuf() Signed-off-by: Duncan Roe <duncan_roe@optusnet.com.au> --- include/libnetfilter_queue/pktbuff.h | 2 + src/extra/pktbuff.c | 82 ++++++++++++++++++++++++++++++++++++ 2 files changed, 84 insertions(+)