From a0c885ae5a79457aa592cb70c27a7dee619762a4 Mon Sep 17 00:00:00 2001
From: Pablo Neira Ayuso <pablo@netfilter.org>
Date: Mon, 16 Apr 2012 19:12:58 +0200
Subject: add new libnetfilter_queue API for libmnl

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 examples/nf-queue.c | 164 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 164 insertions(+)
 create mode 100644 examples/nf-queue.c

(limited to 'examples/nf-queue.c')

diff --git a/examples/nf-queue.c b/examples/nf-queue.c
new file mode 100644
index 0000000..8b4b63d
--- /dev/null
+++ b/examples/nf-queue.c
@@ -0,0 +1,164 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <time.h>
+#include <arpa/inet.h>
+
+#include <libmnl/libmnl.h>
+#include <linux/netfilter.h>
+#include <linux/netfilter/nfnetlink.h>
+
+#include <linux/types.h>
+#include <linux/netfilter/nfnetlink_queue.h>
+
+#include <libnetfilter_queue/libnetfilter_queue.h>
+
+static struct mnl_socket *nl;
+
+static struct nlmsghdr *
+nfq_hdr_put(char *buf, int type, uint32_t queue_num)
+{
+	struct nlmsghdr *nlh = mnl_nlmsg_put_header(buf);
+	nlh->nlmsg_type	= (NFNL_SUBSYS_QUEUE << 8) | type;
+	nlh->nlmsg_flags = NLM_F_REQUEST;
+
+	struct nfgenmsg *nfg = mnl_nlmsg_put_extra_header(nlh, sizeof(*nfg));
+	nfg->nfgen_family = AF_UNSPEC;
+	nfg->version = NFNETLINK_V0;
+	nfg->res_id = htons(queue_num);
+
+	return nlh;
+}
+
+static int
+nfq_send_verdict(int queue_num, uint32_t id)
+{
+	char buf[MNL_SOCKET_BUFFER_SIZE];
+	struct nlmsghdr *nlh;
+	int ret;
+
+	nlh = nfq_hdr_put(buf, NFQNL_MSG_VERDICT, queue_num);
+	nfq_nlmsg_verdict_put(nlh, id, NF_ACCEPT);
+
+	if (mnl_socket_sendto(nl, nlh, nlh->nlmsg_len) < 0) {
+		perror("mnl_socket_send");
+		exit(EXIT_FAILURE);
+	}
+
+	return ret;
+}
+
+static int queue_cb(const struct nlmsghdr *nlh, void *data)
+{
+	struct nfqnl_msg_packet_hdr *ph = NULL;
+	struct nlattr *attr[NFQA_MAX+1];
+	uint32_t id = 0;
+	struct nfgenmsg *nfg;
+
+	if (nfq_nlmsg_parse(nlh, attr) < 0) {
+		perror("problems parsing");
+		return MNL_CB_ERROR;
+	}
+
+	nfg = mnl_nlmsg_get_payload(nlh);
+
+	ph = (struct nfqnl_msg_packet_hdr *)
+		mnl_attr_get_payload(attr[NFQA_PACKET_HDR]);
+	if (ph == NULL) {
+		perror("problems retrieving metaheader");
+		return MNL_CB_ERROR;
+	}
+
+	id = ntohl(ph->packet_id);
+
+	printf("packet received (id=%u hw=0x%04x hook=%u)\n",
+		id, ntohs(ph->hw_protocol), ph->hook);
+
+	nfq_send_verdict(ntohs(nfg->res_id), id);
+
+	return MNL_CB_OK;
+}
+
+int main(int argc, char *argv[])
+{
+	char buf[MNL_SOCKET_BUFFER_SIZE];
+	struct nlmsghdr *nlh;
+	int ret;
+	unsigned int portid, queue_num;
+
+	if (argc != 2) {
+		printf("Usage: %s [queue_num]\n", argv[0]);
+		exit(EXIT_FAILURE);
+	}
+	queue_num = atoi(argv[1]);
+
+	nl = mnl_socket_open(NETLINK_NETFILTER);
+	if (nl == NULL) {
+		perror("mnl_socket_open");
+		exit(EXIT_FAILURE);
+	}
+
+	if (mnl_socket_bind(nl, 0, MNL_SOCKET_AUTOPID) < 0) {
+		perror("mnl_socket_bind");
+		exit(EXIT_FAILURE);
+	}
+	portid = mnl_socket_get_portid(nl);
+
+	nlh = nfq_hdr_put(buf, NFQNL_MSG_CONFIG, 0);
+	nfq_nlmsg_cfg_put_cmd(nlh, AF_INET, NFQNL_CFG_CMD_PF_UNBIND);
+
+	if (mnl_socket_sendto(nl, nlh, nlh->nlmsg_len) < 0) {
+		perror("mnl_socket_send");
+		exit(EXIT_FAILURE);
+	}
+
+	nlh = nfq_hdr_put(buf, NFQNL_MSG_CONFIG, 0);
+	nfq_nlmsg_cfg_put_cmd(nlh, AF_INET, NFQNL_CFG_CMD_PF_BIND);
+
+	if (mnl_socket_sendto(nl, nlh, nlh->nlmsg_len) < 0) {
+		perror("mnl_socket_send");
+		exit(EXIT_FAILURE);
+	}
+
+	nlh = nfq_hdr_put(buf, NFQNL_MSG_CONFIG, queue_num);
+	nfq_nlmsg_cfg_put_cmd(nlh, AF_INET, NFQNL_CFG_CMD_BIND);
+
+	if (mnl_socket_sendto(nl, nlh, nlh->nlmsg_len) < 0) {
+		perror("mnl_socket_send");
+		exit(EXIT_FAILURE);
+	}
+
+	nlh = nfq_hdr_put(buf, NFQNL_MSG_CONFIG, queue_num);
+	nfq_nlmsg_cfg_put_params(nlh, NFQNL_COPY_PACKET, 0xffff);
+
+	if (mnl_socket_sendto(nl, nlh, nlh->nlmsg_len) < 0) {
+		perror("mnl_socket_send");
+		exit(EXIT_FAILURE);
+	}
+
+	ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
+	if (ret == -1) {
+		perror("mnl_socket_recvfrom");
+		exit(EXIT_FAILURE);
+	}
+	while (ret > 0) {
+		uint32_t id;
+
+		ret = mnl_cb_run(buf, ret, 0, portid, queue_cb, NULL);
+		if (ret < 0){
+			perror("mnl_cb_run");
+			exit(EXIT_FAILURE);
+		}
+
+		ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
+		if (ret == -1) {
+			perror("mnl_socket_recvfrom");
+			exit(EXIT_FAILURE);
+		}
+	}
+
+	mnl_socket_close(nl);
+
+	return 0;
+}
-- 
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