tests: conntrackd: add cthelper-test infrastructure

This patch adds the automated testing infrastructure the user-space
helpers. Basically, this adds the `cthelper-test' program that can
be invoked from the command line:

 ./cthelper-test pcaps/oracle-tns-redirect.pcap tns tcp 1521

To test the helper with one PCAP file that contains traces of Oracle TNS
traffic. It also provides tweaks to test the DNAT content mangling code:

 ./cthelper-test pcaps/oracle-tns-redirect.pcap tns tcp 1521 dnat

This will also allow fuzzy testing of user-space helper, for further
validation, not yet implemented.

To compile this tool, you have to run:

./configure
make check

under the qa/cthelper-test/ directory. I'm doing like this because
this directory is not included in the standalone tarball that
make distcheck generates (I don't want to bloat it with development
tools that can be retrieved from the git repository).

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 220 insertions, 0 deletions

diff --git a/tests/conntrackd/cthelper/main.c b/tests/conntrackd/cthelper/main.c
new file mode 100755
index 0000000..f229c5d
--- /dev/null
+++ b/tests/conntrackd/cthelper/main.c
@@ -0,0 +1,220 @@
+#include <stdio.h>
+#include <pcap.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <netinet/ip.h>
+#include <arpa/inet.h>
+#include <string.h>
+#include <dlfcn.h>
+
+#include "ct.h"
+#include "proto.h"
+#include "../../../include/helper.h"
+#include "test.h"
+
+#include <libnetfilter_queue/pktbuff.h>
+
+struct cthelper_test_stats cthelper_test_stats;
+
+enum {
+	TEST_NORMAL = 0,
+	TEST_DNAT,
+};
+
+static int
+cthelper_process_packet(const uint8_t *pkt, uint32_t pktlen,
+			struct ctd_helper *h, int proto, uint16_t port,
+			int type)
+{
+	struct pkt_buff *pktb;
+	struct cthelper_proto_l2l3_helper *l3h;
+	struct cthelper_proto_l4_helper *l4h;
+	unsigned int l3hdr_len, l4protonum;
+	struct nf_ct_entry *ct;
+	int ret, this_proto;
+	uint32_t dataoff, ctinfo = 0;
+
+	l3h = cthelper_proto_l2l3_helper_find(pkt, &l4protonum, &l3hdr_len);
+	if (l3h == NULL) {
+		fprintf(stderr, "Unsupported layer 3 protocol, skipping.\n");
+		return -1;
+	}
+
+	l4h = cthelper_proto_l4_helper_find(pkt, l4protonum);
+	if (l4h == NULL) {
+		fprintf(stderr, "Unsupported layer 4 protocol, skipping.\n");
+		return -1;
+	}
+	/* get layer 3 header. */
+	pkt += l3h->l2hdr_len;
+	pktlen -= l3h->l2hdr_len;
+
+	/* skip packet with mismatching protocol */
+	this_proto = l3h->l4pkt_proto(pkt);
+	if (this_proto != proto) {
+		cthelper_test_stats.pkt_mismatch_proto++;
+		return 0;
+	}
+
+	/* Look for the fake conntrack. */
+	ct = ct_find(pkt, l3hdr_len, l3h, l4h, &ctinfo);
+	if (ct == NULL) {
+		/* It doesn't exist any, create one. */
+		ct = ct_alloc(pkt, l3hdr_len, l3h, l4h);
+		if (ct == NULL) {
+			fprintf(stderr, "Not enough memory\n");
+			return -1;
+		}
+		ct_add(ct);
+		ctinfo += IP_CT_NEW;
+	} else
+		ctinfo += IP_CT_ESTABLISHED;
+
+	/* skip packets with mismatching ports */
+	if (!l4h->l4ct_cmp_port(ct->myct->ct, ntohs(port))) {
+		cthelper_test_stats.pkt_mismatch_port++;
+		return -1;
+	}
+
+	/*
+	 * FIXME: reminder, implement this below in the kernel for cthelper.
+	 */
+
+	/* This packet contains no data, skip it. */
+/*	if (l4h->l4pkt_no_data && l4h->l4pkt_no_data(pkt + l3hdr_len)) {
+		NFG_DEBUG("skipping packet with no data\n");
+		continue;
+	} */
+
+	/* Create the fake network buffer. */
+	pktb = pktb_alloc(AF_INET, pkt, pktlen, 128);
+	if (pktb == NULL) {
+		fprintf(stderr, "Not enough memory\n");
+		return -1;
+	}
+
+	dataoff = l3h->l3pkt_hdr_len(pkt);
+	if (dataoff > pktb_len(pktb)) {
+		fprintf(stderr, "wrong layer 3 offset: %d > %d\n",
+			dataoff, pktb_len(pktb));
+		return -1;
+	}
+
+	/* tweak to run DNAT mangling code using the same PCAP file. */
+	if (type == TEST_DNAT) {
+		struct nf_conntrack *tmp = ct->myct->ct;
+		/* as long as this is tested, who cares the destination IP? */
+		in_addr_t addr = inet_addr("1.1.1.1");
+
+		/* clone the real conntrack, to add DNAT information */
+		ct->myct->ct = nfct_clone(ct->myct->ct);
+		/* set fake DNAT information */
+		nfct_set_attr_u32(ct->myct->ct, ATTR_STATUS, IPS_DST_NAT);
+		nfct_set_attr_u32(ct->myct->ct, ATTR_ORIG_IPV4_DST, addr);
+		/* pass it to helper */
+		ret = h->cb(pktb, dataoff, ct->myct, ctinfo);
+		/* restore real conntrack */
+		nfct_destroy(ct->myct->ct);
+		ct->myct->ct = tmp;
+
+		if (pktb_mangled(pktb)) {
+			int i;
+			uint8_t *data = pktb_network_header(pktb);
+
+			printf("\e[1;31mmangled content: ", pktb_len(pktb));
+
+			for (i=0; i < pktb_len(pktb); i++)
+				printf("%c", data[i]);
+
+			printf("\e[0m\n");
+		}
+	} else
+		ret = h->cb(pktb, dataoff, ct->myct, ctinfo);
+
+	pktb_free(pktb);
+
+	return ret;
+}
+
+static int
+cthelper_test(const char *pcapfile, const char *helper_name,
+	      int l4proto, uint16_t port, int type)
+{
+	struct pcap_pkthdr pcaph;
+	char errbuf[PCAP_ERRBUF_SIZE];
+	const u_char *pkt;
+	pcap_t *handle;
+	struct ctd_helper *h;
+
+	h = helper_find("/usr/lib/conntrack-tools",
+			helper_name, l4proto, RTLD_NOW);
+	if (h == NULL) {
+		fprintf(stderr, "couldn't find helper: %s\n", helper_name);
+		return -1;
+	}
+
+	handle = pcap_open_offline(pcapfile, errbuf);
+	if (handle == NULL) {
+		fprintf(stderr, "couldn't open pcap file %s: %s\n",
+				pcapfile, errbuf);
+		return -1;
+	}
+	while ((pkt = pcap_next(handle, &pcaph)) != NULL) {
+		cthelper_test_stats.pkts++;
+		cthelper_process_packet(pkt, pcaph.caplen, h, l4proto, port,
+					type);
+	}
+
+	ct_flush();
+	pcap_close(handle);
+	return 0;
+}
+
+int main(int argc, char *argv[])
+{
+	int ret, l4proto, type = TEST_NORMAL;
+
+	if (argc < 5 || argc > 6) {
+		fprintf(stderr, "Wrong usage:\n");
+		fprintf(stderr, "%s <pcap_file> <helper-name> <proto> "
+				"<port> [dnat]\n",
+				argv[0]);
+		fprintf(stderr, "example: %s file.pcap ftp tcp 21\n", argv[0]);
+		exit(EXIT_FAILURE);
+	}
+	if (strncmp("tcp", argv[3], strlen("tcp")) == 0)
+		l4proto = IPPROTO_TCP;
+	else if (strncmp("udp", argv[3], strlen("udp")) == 0)
+		l4proto = IPPROTO_UDP;
+	else {
+		fprintf(stderr, "%s not supported, send a patch to Pablo\n",
+			argv[3]);
+		exit(EXIT_FAILURE);
+	}
+	if (argc == 6) {
+		if (strncmp("dnat", argv[5], strlen("dnat")) == 0) {
+			type = TEST_DNAT;
+			printf("test dnat\n");
+		}
+	}
+
+	/* Initialization of supported layer 3 and 4 protocols here. */
+	l2l3_ipv4_init();
+	l4_tcp_init();
+	l4_udp_init();
+
+	if (cthelper_test(argv[1], argv[2], l4proto, atoi(argv[4]), type) < 0)
+		ret = EXIT_FAILURE;
+	else
+		ret = EXIT_SUCCESS;
+
+	printf("\e[1;34mTest results: expect_created=%d packets=%d "
+	       "packets_skipped=%d\e[0m\n",
+		cthelper_test_stats.ct_expect_created,
+		cthelper_test_stats.pkts,
+		cthelper_test_stats.pkt_mismatch_proto +
+		cthelper_test_stats.pkt_mismatch_port);
+
+	return ret;
+}