Move kernel GTP support from ggsn/ to lib/

This way, the IP address / route handling between TUN devices and kernel
GTP can be shared, which will provide not only a unified codebase but
also a more consistent behavior.

This also paves the road for to use kernel GTP from sgsnemu in the future.

Related: OS#3214
Change-Id: Ic53a971136edd0d8871fbd6746d7b0090ce3a188

1 files changed, 160 insertions, 0 deletions

diff --git a/lib/gtp-kernel.c b/lib/gtp-kernel.c
new file mode 100644
index 0000000..48811bc
--- /dev/null
+++ b/lib/gtp-kernel.c
@@ -0,0 +1,160 @@
+#ifdef __linux__
+#define _GNU_SOURCE 1		/* strdup() prototype, broken arpa/inet.h */
+#endif
+
+#include "../config.h"
+
+#ifdef HAVE_STDINT_H
+#include <stdint.h>
+#endif
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <inttypes.h>
+#include <sys/types.h>
+#include <arpa/inet.h>
+#include <net/if.h>
+
+#include <libgtpnl/gtp.h>
+#include <libgtpnl/gtpnl.h>
+#include <libmnl/libmnl.h>
+
+#include <errno.h>
+
+#include <time.h>
+
+#include "../lib/tun.h"
+#include "../lib/syserr.h"
+#include "../gtp/pdp.h"
+#include "../gtp/gtp.h"
+
+#include <libgtpnl/gtp.h>
+#include <libgtpnl/gtpnl.h>
+#include <libmnl/libmnl.h>
+
+#include "gtp-kernel.h"
+
+static void pdp_debug(const char *prefix, const char *devname, struct pdp_t *pdp)
+{
+	struct in46_addr ia46;
+	struct in_addr ia;
+
+	in46a_from_eua(&pdp->eua, &ia46);
+	gsna2in_addr(&ia, &pdp->gsnrc);
+
+	LOGPDPX(DGGSN, LOGL_DEBUG, pdp, "%s %s v%u TEID %"PRIx64" EUA=%s SGSN=%s\n", prefix,
+		devname, pdp->version,
+		pdp->version == 0 ? pdp_gettid(pdp->imsi, pdp->nsapi) : pdp->teid_gn,
+		in46a_ntoa(&ia46), inet_ntoa(ia));
+}
+
+static struct {
+	int			genl_id;
+	struct mnl_socket	*nl;
+} gtp_nl;
+
+static int gtp_kernel_init_once(void)
+{
+	/* only initialize once */
+	if (gtp_nl.nl)
+		return 0;
+
+	gtp_nl.nl = genl_socket_open();
+	if (gtp_nl.nl == NULL) {
+		LOGP(DGGSN, LOGL_ERROR, "cannot create genetlink socket\n");
+		return -1;
+	}
+	gtp_nl.genl_id = genl_lookup_family(gtp_nl.nl, "gtp");
+	if (gtp_nl.genl_id < 0) {
+		LOGP(DGGSN, LOGL_ERROR, "cannot lookup GTP genetlink ID\n");
+		genl_socket_close(gtp_nl.nl);
+		gtp_nl.nl = NULL;
+		return -1;
+	}
+	LOGP(DGGSN, LOGL_NOTICE, "Initialized GTP kernel mode (genl ID is %d)\n", gtp_nl.genl_id);
+
+	return 0;
+}
+
+int gtp_kernel_create(int dest_ns, const char *devname, int fd0, int fd1u)
+{
+	if (gtp_kernel_init_once() < 0)
+		return -1;
+
+	return gtp_dev_create(dest_ns, devname, fd0, fd1u);
+}
+
+int gtp_kernel_create_sgsn(int dest_ns, const char *devname, int fd0, int fd1u)
+{
+	if (gtp_kernel_init_once() < 0)
+		return -1;
+
+	return gtp_dev_create_sgsn(dest_ns, devname, fd0, fd1u);
+}
+
+void gtp_kernel_stop(const char *devname)
+{
+	gtp_dev_destroy(devname);
+}
+
+int gtp_kernel_tunnel_add(struct pdp_t *pdp, const char *devname)
+{
+	struct in_addr ms, sgsn;
+	struct gtp_tunnel *t;
+	int ret;
+
+	pdp_debug(__func__, devname, pdp);
+
+	t = gtp_tunnel_alloc();
+	if (t == NULL)
+		return -1;
+
+	memcpy(&ms, &pdp->eua.v[2], sizeof(struct in_addr));
+	memcpy(&sgsn, &pdp->gsnrc.v[0], sizeof(struct in_addr));
+
+	gtp_tunnel_set_ifidx(t, if_nametoindex(devname));
+	gtp_tunnel_set_version(t, pdp->version);
+	gtp_tunnel_set_ms_ip4(t, &ms);
+	gtp_tunnel_set_sgsn_ip4(t, &sgsn);
+	if (pdp->version == 0) {
+		gtp_tunnel_set_tid(t, pdp_gettid(pdp->imsi, pdp->nsapi));
+		gtp_tunnel_set_flowid(t, pdp->flru);
+	} else {
+		gtp_tunnel_set_i_tei(t, pdp->teid_own);
+		/* use the TEI advertised by SGSN when sending packets
+		 * towards the SGSN */
+		gtp_tunnel_set_o_tei(t, pdp->teid_gn);
+	}
+
+	ret = gtp_add_tunnel(gtp_nl.genl_id, gtp_nl.nl, t);
+	gtp_tunnel_free(t);
+
+	return ret;
+}
+
+int gtp_kernel_tunnel_del(struct pdp_t *pdp, const char *devname)
+{
+	struct gtp_tunnel *t;
+	int ret;
+
+	pdp_debug(__func__, devname, pdp);
+
+	t = gtp_tunnel_alloc();
+	if (t == NULL)
+		return -1;
+
+	gtp_tunnel_set_ifidx(t, if_nametoindex(devname));
+	gtp_tunnel_set_version(t, pdp->version);
+	if (pdp->version == 0) {
+		gtp_tunnel_set_tid(t, pdp_gettid(pdp->imsi, pdp->nsapi));
+		gtp_tunnel_set_flowid(t, pdp->flru);
+	} else {
+		gtp_tunnel_set_i_tei(t, pdp->teid_own);
+	}
+
+	ret = gtp_del_tunnel(gtp_nl.genl_id, gtp_nl.nl, t);
+	gtp_tunnel_free(t);
+
+	return ret;
+}