create new project.

1 files changed, 213 insertions, 0 deletions

diff --git a/src/packet_io/nf-queue.c b/src/packet_io/nf-queue.c
new file mode 100644
index 0000000..c2bc6cc
--- /dev/null
+++ b/src/packet_io/nf-queue.c
@@ -0,0 +1,213 @@
+#include <errno.h>
+#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>
+
+/* only for NFQA_CT, not needed otherwise: */
+#include <linux/netfilter/nfnetlink_conntrack.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 void
+nfq_send_verdict(int queue_num, uint32_t id)
+{
+	char buf[MNL_SOCKET_BUFFER_SIZE];
+	struct nlmsghdr *nlh;
+	struct nlattr *nest;
+
+	nlh = nfq_hdr_put(buf, NFQNL_MSG_VERDICT, queue_num);
+	nfq_nlmsg_verdict_put(nlh, id, NF_ACCEPT);
+
+	/* example to set the connmark. First, start NFQA_CT section: */
+	nest = mnl_attr_nest_start(nlh, NFQA_CT);
+
+	/* then, add the connmark attribute: */
+	mnl_attr_put_u32(nlh, CTA_MARK, htonl(42));
+	/* more conntrack attributes, e.g. CTA_LABEL, could be set here */
+
+	/* end conntrack section */
+	mnl_attr_nest_end(nlh, nest);
+
+	if (mnl_socket_sendto(nl, nlh, nlh->nlmsg_len) < 0) {
+		perror("mnl_socket_send");
+		exit(EXIT_FAILURE);
+	}
+}
+
+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, skbinfo;
+	struct nfgenmsg *nfg;
+	uint16_t plen;
+
+	if (nfq_nlmsg_parse(nlh, attr) < 0) {
+		perror("problems parsing");
+		return MNL_CB_ERROR;
+	}
+
+	nfg = mnl_nlmsg_get_payload(nlh);
+
+	if (attr[NFQA_PACKET_HDR] == NULL) {
+		fputs("metaheader not set\n", stderr);
+		return MNL_CB_ERROR;
+	}
+
+	ph = mnl_attr_get_payload(attr[NFQA_PACKET_HDR]);
+
+	plen = mnl_attr_get_payload_len(attr[NFQA_PAYLOAD]);
+	/* void *payload = mnl_attr_get_payload(attr[NFQA_PAYLOAD]); */
+
+	skbinfo = attr[NFQA_SKB_INFO] ? ntohl(mnl_attr_get_u32(attr[NFQA_SKB_INFO])) : 0;
+
+	if (attr[NFQA_CAP_LEN]) {
+		uint32_t orig_len = ntohl(mnl_attr_get_u32(attr[NFQA_CAP_LEN]));
+		if (orig_len != plen)
+			printf("truncated ");
+	}
+
+	if (skbinfo & NFQA_SKB_GSO)
+		printf("GSO ");
+
+	id = ntohl(ph->packet_id);
+	printf("packet received (id=%u hw=0x%04x hook=%u, payload len %u",
+		id, ntohs(ph->hw_protocol), ph->hook, plen);
+
+	/*
+	 * ip/tcp checksums are not yet valid, e.g. due to GRO/GSO.
+	 * The application should behave as if the checksums are correct.
+	 *
+	 * If these packets are later forwarded/sent out, the checksums will
+	 * be corrected by kernel/hardware.
+	 */
+	if (skbinfo & NFQA_SKB_CSUMNOTREADY)
+		printf(", checksum not ready");
+	puts(")");
+
+	nfq_send_verdict(ntohs(nfg->res_id), id);
+
+	return MNL_CB_OK;
+}
+
+int main(int argc, char *argv[])
+{
+	char *buf;
+	/* largest possible packet payload, plus netlink data overhead: */
+	size_t sizeof_buf = 0xffff + (MNL_SOCKET_BUFFER_SIZE/2);
+	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);
+
+	buf = malloc(sizeof_buf);
+	if (!buf) {
+		perror("allocate receive buffer");
+		exit(EXIT_FAILURE);
+	}
+
+	/* PF_(UN)BIND is not needed with kernels 3.8 and later */
+	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);
+
+	mnl_attr_put_u32(nlh, NFQA_CFG_FLAGS, htonl(NFQA_CFG_F_GSO));
+	mnl_attr_put_u32(nlh, NFQA_CFG_MASK, htonl(NFQA_CFG_F_GSO));
+
+	if (mnl_socket_sendto(nl, nlh, nlh->nlmsg_len) < 0) {
+		perror("mnl_socket_send");
+		exit(EXIT_FAILURE);
+	}
+
+	/* ENOBUFS is signalled to userspace when packets were lost
+	 * on kernel side.  In most cases, userspace isn't interested
+	 * in this information, so turn it off.
+	 */
+	ret = 1;
+	mnl_socket_setsockopt(nl, NETLINK_NO_ENOBUFS, &ret, sizeof(int));
+
+	for (;;) {
+		ret = mnl_socket_recvfrom(nl, buf, sizeof_buf);
+		if (ret == -1) {
+			perror("mnl_socket_recvfrom");
+			exit(EXIT_FAILURE);
+		}
+
+		ret = mnl_cb_run(buf, ret, 0, portid, queue_cb, NULL);
+		if (ret < 0){
+			perror("mnl_cb_run");
+			exit(EXIT_FAILURE);
+		}
+	}
+
+	mnl_socket_close(nl);
+
+	return 0;
+}