1 files changed, 122 insertions, 37 deletions

diff --git a/src/extra/pktbuff.c b/src/extra/pktbuff.c
index c95384f..40d2250 100644
--- a/src/extra/pktbuff.c
+++ b/src/extra/pktbuff.c
@@ -23,12 +23,58 @@
 /**
  * \defgroup pktbuff User-space network packet buffer
  *
- * This library provides the user-space network packet buffer. This abstraction
- * is strongly inspired by Linux kernel network buffer, the so-called sk_buff.
+ * These functions provide the user-space network packet buffer.
+ * This abstraction is strongly inspired by Linux kernel network buffer,
+ * the so-called sk_buff.
+ *
+ * \manonly
+.SH SYNOPSIS
+.nf
+\fB
+#include <libmnl/libmnl.h>
+#include <libnetfilter_queue/pktbuff.h>
+\endmanonly
  *
  * @{
  */
 
+static int __pktb_setup(int family, struct pkt_buff *pktb)
+{
+	struct ethhdr *ethhdr;
+
+	switch (family) {
+	case AF_INET:
+	case AF_INET6:
+		pktb->network_header = pktb->data;
+		break;
+	case AF_BRIDGE:
+		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;
+			return -1;
+		}
+		break;
+	}
+
+	return 0;
+}
+
+static void pktb_setup_metadata(struct pkt_buff *pktb, void *pkt_data,
+				size_t len, size_t extra)
+{
+	pktb->len = len;
+	pktb->data_len = len + extra;
+	pktb->data = pkt_data;
+}
+
 /**
  * pktb_alloc - allocate a new packet buffer
  * \param family Indicate what family. Currently supported families are
@@ -38,7 +84,12 @@
  * \param extra Extra memory in the tail to be allocated (for mangling)
  *
  * This function returns a packet buffer that contains the packet data and
- * some extra memory room in the tail (if requested).
+ * some extra memory room in the tail (if requested). This function copies
+ * the memory area provided as a pointer to packet data into the packet buffer
+ * structure.
+ *
+ * The extra length provides extra packet data room at the tail of the packet
+ * buffer in case you need to mangle it.
  *
  * \return Pointer to a new userspace packet buffer or NULL on failure.
  * \par Errors
@@ -52,7 +103,6 @@ EXPORT_SYMBOL
 struct pkt_buff *pktb_alloc(int family, void *data, size_t len, size_t extra)
 {
 	struct pkt_buff *pktb;
-	struct ethhdr *ethhdr;
 	void *pkt_data;
 
 	pktb = calloc(1, sizeof(struct pkt_buff) + len + extra);
@@ -63,34 +113,44 @@ struct pkt_buff *pktb_alloc(int family, void *data, size_t len, size_t extra)
 	pkt_data = (uint8_t *)pktb + sizeof(struct pkt_buff);
 	memcpy(pkt_data, data, len);
 
-	pktb->len = len;
-	pktb->data_len = len + extra;
+	pktb_setup_metadata(pktb, pkt_data, len, extra);
 
-	pktb->data = pkt_data;
-	pktb->tail = pktb->data + len;
+	if (__pktb_setup(family, pktb) < 0) {
+		free(pktb);
+		return NULL;
+	}
 
-	switch(family) {
-	case AF_INET:
-	case AF_INET6:
-		pktb->network_header = pktb->data;
-		break;
-	case AF_BRIDGE:
-		ethhdr = (struct ethhdr *)pktb->data;
-		pktb->mac_header = pktb->data;
+	return pktb;
+}
+
+/**
+ * pktb_setup_raw - set up a packet buffer from memory area
+ * \param pktb Pointer to memory of length pktb_head_size() bytes
+ * \param family Supported families are AF_BRIDGE, AF_INET & AF_INET6.
+ * \param data Pointer to packet data
+ * \param len Packet data length
+ * \param extra Extra memory available after packet data (for mangling).
+ *
+ * Use this function to set up a packet buffer from a memory area, minimum size
+ * of such memory area must be pktb_head_size(). This function attaches the
+ * packet data that is provided to the packet buffer (data is not copied). Use
+ * this function as an alternative to the pktb_alloc() interface for more
+ * control on memory management.
+ *
+ * \return Pointer to a new userspace packet buffer or NULL on failure.
+ * \par Errors
+ * __EPROTONOSUPPORT__ _family_ was __AF_BRIDGE__ and this is not an IP packet
+ * (v4 or v6)
+ */
+EXPORT_SYMBOL
+struct pkt_buff *pktb_setup_raw(void *pktb, int family, void *data,
+				size_t len, size_t extra)
+{
+	memset(pktb, 0, sizeof (struct pkt_buff));
+	pktb_setup_metadata(pktb, data, len, extra);
+	if (__pktb_setup(family, pktb) < 0)
+		pktb = NULL;
 
-		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;
 }
 
@@ -140,21 +200,37 @@ void pktb_free(struct pkt_buff *pktb)
  * \n
  * 1. Functions to get values of members of opaque __struct pktbuff__, described
  * below
- * \n
+ *
  * 2. Internal functions, described in Module __Internal functions__
  *
+ * \manonly
+.SH SYNOPSIS
+.nf
+\fB
+#include <libmnl/libmnl.h>
+#include <libnetfilter_queue/pktbuff.h>
+\endmanonly
+ *
  * @{
  */
 
 /**
- * \defgroup uselessfns Internal functions
+ * \defgroup do_not_use Internal functions
  *
- * \warning Do not use these functions. Instead, always use the mangle
+ * Do not use these functions. Instead, always use the mangle
  * function appropriate to the level at which you are working.
  * \n
  * pktb_mangle() uses all the below functions except _pktb_pull_, which is not
  * used by anything.
  *
+ * \manonly
+.SH SYNOPSIS
+.nf
+\fB
+#include <libmnl/libmnl.h>
+#include <libnetfilter_queue/pktbuff.h>
+\endmanonly
+ *
  * @{
  */
 
@@ -190,7 +266,6 @@ void pktb_pull(struct pkt_buff *pktb, unsigned int len)
 EXPORT_SYMBOL
 void pktb_put(struct pkt_buff *pktb, unsigned int len)
 {
-	pktb->tail += len;
 	pktb->len += len;
 }
 
@@ -203,7 +278,6 @@ EXPORT_SYMBOL
 void pktb_trim(struct pkt_buff *pktb, unsigned int len)
 {
 	pktb->len = len;
-	pktb->tail = pktb->data + len;
 }
 
 /**
@@ -279,7 +353,6 @@ static int pktb_expand_tail(struct pkt_buff *pktb, int extra)
 		return 0;
 
 	pktb->len += extra;
-	pktb->tail = pktb->tail + extra;
 	return 1;
 }
 
@@ -310,7 +383,7 @@ static int enlarge_pkt(struct pkt_buff *pktb, unsigned int extra)
  * excess of \b rep_len over \b match_len
  \warning pktb_mangle does not update any checksums. Developers should use the
  appropriate mangler for the protocol level: nfq_ip_mangle(),
- nfq_tcp_mangle_ipv4() or nfq_udp_mangle_ipv4(). IPv6 versions are planned.
+ nfq_tcp_mangle_ipv4(), nfq_udp_mangle_ipv4() or IPv6 variants.
  \n
  It is appropriate to use pktb_mangle to change the MAC header.
  */
@@ -334,7 +407,7 @@ int pktb_mangle(struct pkt_buff *pktb,
 	/* move post-replacement */
 	memmove(data + match_offset + rep_len,
 		data + match_offset + match_len,
-		pktb->tail - (pktb->network_header + dataoff +
+		pktb_tail(pktb) - (pktb->network_header + dataoff +
 			     match_offset + match_len));
 
 	/* insert data from buffer */
@@ -366,5 +439,17 @@ bool pktb_mangled(const struct pkt_buff *pktb)
 }
 
 /**
+ * pktb_head_size - get number of bytes needed for a packet buffer
+ *                  (control part only)
+ * \return size of struct pkt_buff
+ */
+
+EXPORT_SYMBOL
+size_t pktb_head_size(void)
+{
+	return sizeof(struct pkt_buff);
+}
+
+/**
  * @}
  */