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/udp.c | 132 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 132 insertions(+)
 create mode 100644 src/extra/udp.c

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

diff --git a/src/extra/udp.c b/src/extra/udp.c
new file mode 100644
index 0000000..c0b1b7d
--- /dev/null
+++ b/src/extra/udp.c
@@ -0,0 +1,132 @@
+/*
+ * (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 <stdio.h>
+#include <arpa/inet.h>
+#include <netinet/ip.h>
+#include <netinet/ip6.h>
+#include <netinet/udp.h>
+
+#include <libnetfilter_queue/libnetfilter_queue.h>
+#include <libnetfilter_queue/libnetfilter_queue_udp.h>
+#include <libnetfilter_queue/pktbuff.h>
+
+#include "internal.h"
+
+/**
+ * \defgroup udp UDP helper functions
+ * @{
+ */
+
+/**
+ * nfq_udp_get_hdr - get the UDP header.
+ * \param head: pointer to the beginning of the packet
+ * \param tail: pointer to the tail of the packet
+ *
+ * This function returns NULL if invalid UDP header is found. On success,
+ * it returns the UDP header.
+ */
+struct udphdr *nfq_udp_get_hdr(struct pkt_buff *pktb)
+{
+	if (pktb->transport_header == NULL)
+		return NULL;
+
+	/* No room for the UDP header. */
+	if (pktb->tail - pktb->transport_header < sizeof(struct udphdr))
+		return NULL;
+
+	return (struct udphdr *)pktb->transport_header;
+}
+EXPORT_SYMBOL(nfq_udp_get_hdr);
+
+/**
+ * nfq_udp_get_payload - get the UDP packet payload.
+ * \param udph: the pointer to the UDP header.
+ * \param tail: pointer to the tail of the packet
+ */
+void *nfq_udp_get_payload(struct udphdr *udph, struct pkt_buff *pktb)
+{
+	unsigned int doff = udph->len;
+
+	/* malformed UDP data offset. */
+	if (pktb->transport_header + doff > pktb->tail)
+		return NULL;
+
+	return pktb->transport_header + doff;
+}
+EXPORT_SYMBOL(nfq_udp_get_payload);
+
+/**
+ * nfq_udp_get_payload_len - get the udp packet payload.
+ * \param udp: the pointer to the udp header.
+ */
+unsigned int nfq_udp_get_payload_len(struct udphdr *udph, struct pkt_buff *pktb)
+{
+	return pktb->tail - pktb->transport_header;
+}
+EXPORT_SYMBOL(nfq_udp_get_payload_len);
+
+/**
+ * nfq_udp_set_checksum_ipv4 - computes a IPv4/TCP packet's segment
+ * \param iphdrp: pointer to the ip header
+ * \param ippayload: payload of the ip packet
+ *
+ * \returns the checksum of the udp segment.
+ *
+ * \see nfq_pkt_compute_ip_checksum
+ * \see nfq_pkt_compute_udp_checksum
+ */
+void
+nfq_udp_compute_checksum_ipv4(struct udphdr *udph, struct iphdr *iph)
+{
+	/* checksum field in header needs to be zero for calculation. */
+	udph->check = 0;
+	udph->check = checksum_tcpudp_ipv4(iph);
+}
+EXPORT_SYMBOL(nfq_udp_compute_checksum_ipv4);
+
+/**
+ * nfq_udp_set_checksum_ipv6 - computes a IPv6/TCP packet's segment
+ * \param iphdrp: pointer to the ip header
+ * \param ippayload: payload of the ip packet
+ *
+ * \returns the checksum of the udp segment.
+ *
+ * \see nfq_pkt_compute_ip_checksum
+ * \see nfq_pkt_compute_udp_checksum
+ */
+void
+nfq_udp_compute_checksum_ipv6(struct udphdr *udph, struct ip6_hdr *ip6h)
+{
+	/* checksum field in header needs to be zero for calculation. */
+	udph->check = 0;
+	udph->check = checksum_tcpudp_ipv6(ip6h, udph);
+}
+EXPORT_SYMBOL(nfq_udp_compute_checksum_ipv6);
+
+/**
+ * nfq_pkt_snprintf_udp_hdr - print udp header into one buffer in a humnan
+ * readable way
+ * \param buf: pointer to buffer that is used to print the object
+ * \param size: size of the buffer (or remaining room in it).
+ * \param udp: pointer to a valid udp header.
+ *
+ */
+int nfq_udp_snprintf(char *buf, size_t size, const struct udphdr *udph)
+{
+	return snprintf(buf, size, "SPT=%u DPT=%u ",
+			htons(udph->source), htons(udph->dest));
+}
+EXPORT_SYMBOL(nfq_udp_snprintf);
+
+/**
+ * @}
+ */
-- 
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