From f40eabb01163f383e2471942da45f32361031e39 Mon Sep 17 00:00:00 2001
From: Pablo Neira Ayuso <pablo@netfilter.org>
Date: Mon, 14 May 2012 13:14:14 +0200
Subject: add pkt_buff and protocol helper functions

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 src/extra/pktbuff.c | 142 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 142 insertions(+)
 create mode 100644 src/extra/pktbuff.c

(limited to 'src/extra/pktbuff.c')

diff --git a/src/extra/pktbuff.c b/src/extra/pktbuff.c
new file mode 100644
index 0000000..809953b
--- /dev/null
+++ b/src/extra/pktbuff.c
@@ -0,0 +1,142 @@
+/*
+ * (C) 2012 by Pablo Neira Ayuso <pablo@netfilter.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This code has been sponsored by Vyatta Inc. <http://www.vyatta.com>
+ */
+
+#include <stdlib.h>
+#include <string.h> /* for memcpy */
+
+#include <netinet/if_ether.h>
+#include <netinet/ip.h>
+#include <netinet/tcp.h>
+
+#include "internal.h"
+
+/**
+ * \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.
+ */
+
+/**
+ * pktb_alloc - allocate a new packet buffer
+ * \param family Indicate what family, eg. 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)
+ *
+ * This function returns a packet buffer that contains the packet data and
+ * some extra memory room in the tail (in case of requested).
+ *
+ * \return a pointer to a new queue handle or NULL on failure.
+ */
+struct pkt_buff *
+pktb_alloc(int family, void *data, size_t len, size_t extra)
+{
+	struct pkt_buff *pktb;
+	void *pkt_data;
+
+	pktb = calloc(1, sizeof(struct pkt_buff) + len + extra);
+	if (pktb == NULL)
+		return NULL;
+
+	/* Better make sure alignment is correct. */
+	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:
+		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:
+			pktb->network_header = pktb->data + ETH_HLEN;
+			break;
+		default:
+			/* This protocol is unsupported. */
+			free(pktb);
+			return NULL;
+		}
+		break;
+	}
+	}
+	return pktb;
+}
+
+uint8_t *pktb_data(struct pkt_buff *pktb)
+{
+	return pktb->data;
+}
+
+uint32_t pktb_len(struct pkt_buff *pktb)
+{
+	return pktb->len;
+}
+
+void pktb_free(struct pkt_buff *pktb)
+{
+	free(pktb);
+}
+
+void pktb_push(struct pkt_buff *pktb, unsigned int len)
+{
+	pktb->data += len;
+}
+
+void pktb_pull(struct pkt_buff *pktb, unsigned int len)
+{
+	pktb->data -= len;
+}
+
+void pktb_put(struct pkt_buff *pktb, unsigned int len)
+{
+	pktb->tail += len;
+}
+
+void pktb_trim(struct pkt_buff *pktb, unsigned int len)
+{
+	pktb->len = len;
+}
+
+unsigned int pktb_tailroom(struct pkt_buff *pktb)
+{
+	return pktb->data_len - pktb->len;
+}
+
+uint8_t *pktb_mac_header(struct pkt_buff *pktb)
+{
+	return pktb->mac_header;
+}
+
+uint8_t *pktb_network_header(struct pkt_buff *pktb)
+{
+	return pktb->network_header;
+}
+
+uint8_t *pktb_transport_header(struct pkt_buff *pktb)
+{
+	return pktb->transport_header;
+}
+
+/**
+ * @}
+ */
-- 
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