15 Oct
2015
15 Oct
'15
10:13 p.m.
Sponsored-by: On-Waves ehi
diff --git a/openbsc/src/gprs/Makefile.am b/openbsc/src/gprs/Makefile.am
index f2f914d..d571d8d 100644
--- a/openbsc/src/gprs/Makefile.am
+++ b/openbsc/src/gprs/Makefile.am
@@ -35,4 +35,4 @@ osmo_sgsn_LDADD = \
$(LIBCRYPTO_LIBS) -lrt
osmo_gtphub_SOURCES = gtphub_main.c gtphub.c
-osmo_gtphub_LDADD = $(LIBOSMOCORE_LIBS) -lrt
+osmo_gtphub_LDADD = -lgtp $(LIBOSMOCORE_LIBS) -lrt
diff --git a/openbsc/src/gprs/gtphub.c b/openbsc/src/gprs/gtphub.c
index a80243c..208b623 100644
--- a/openbsc/src/gprs/gtphub.c
+++ b/openbsc/src/gprs/gtphub.c
@@ -24,6 +24,8 @@
#include <inttypes.h>
#include <netinet/in.h>
+#include <gtp.h>
+
#include <openbsc/gtphub.h>
#include <openbsc/debug.h>
@@ -46,6 +48,150 @@ typedef int (*osmo_fd_cb_t)(struct osmo_fd *fd, unsigned int what);
#define __llist_first(head) (((head)->next == (head)) ? NULL : (head)->next)
#define llist_first(head, type, entry) llist_entry(__llist_first(head), type, entry)
+/* TODO duplicated from openggsn/gtp/gtpie.h */
+#define ntoh16(x) ntohs(x)
+#define ntoh32(x) ntohl(x)
+
+/* TODO move GTP header stuff to openggsn/gtp/ ? See gtp_decaps*() */
+
+enum gtp_rc {
+ GTP_RC_UNKNOWN = 0,
+ GTP_RC_TINY = 1, /* no IEs (like ping/pong) */
+ GTP_RC_PDU = 2, /* a real packet with IEs */
+
+ GTP_RC_TOOSHORT = -1,
+ GTP_RC_UNSUPPORTED_VERSION = -2,
+ GTP_RC_INVALID_IE = -3,
+};
+
+struct gtp_packet_desc {
+ const union gtp_packet *data;
+ int data_len;
+ int header_len;
+ int version;
+ int rc;
+};
+
+/* Validate GTP version 0 data; analogous to validate_gtp1_header(), see there.
+ */
+void validate_gtp0_header(struct gtp_packet_desc *p)
+{
+ const struct gtp0_header *pheader = &(p->data->gtp0.h);
+ p->rc = GTP_RC_UNKNOWN;
+ p->header_len = 0;
+
+ OSMO_ASSERT(p->data_len >= 1);
+ OSMO_ASSERT(p->version == 0);
+
+ if (p->data_len < GTP0_HEADER_SIZE) {
+ LOGERR("GTP0 packet too short: %d\n", p->data_len);
+ p->rc = GTP_RC_TOOSHORT;
+ return;
+ }
+
+ if (p->data_len == GTP0_HEADER_SIZE) {
+ p->rc = GTP_RC_TINY;
+ p->header_len = GTP0_HEADER_SIZE;
+ return;
+ }
+
+ /* Check packet length field versus length of packet */
+ if (p->data_len != (ntoh16(pheader->length) + GTP0_HEADER_SIZE)) {
+ LOGERR("GTP packet length field (%d + %d) does not match"
+ " actual length (%d)\n",
+ GTP0_HEADER_SIZE, (int)ntoh16(pheader->length),
+ p->data_len);
+ p->rc = GTP_RC_TOOSHORT;
+ return;
+ }
+
+ p->header_len = GTP0_HEADER_SIZE;
+ p->rc = GTP_RC_PDU;
+}
+
+/* Validate GTP version 1 data, and update p->rc with the result, as well as
+ * p->header_len in case of a valid header. */
+void validate_gtp1_header(struct gtp_packet_desc *p)
+{
+ const struct gtp1_header_long *pheader = &(p->data->gtp1l.h);
+ p->rc = GTP_RC_UNKNOWN;
+ p->header_len = 0;
+
+ OSMO_ASSERT(p->data_len >= 1);
+ OSMO_ASSERT(p->version == 1);
+
+ if ((p->data_len < GTP1_HEADER_SIZE_LONG)
+ && (p->data_len != GTP1_HEADER_SIZE_SHORT)){
+ LOGERR("GTP packet too short: %d\n", p->data_len);
+ p->rc = GTP_RC_TOOSHORT;
+ return;
+ }
+
+ if (p->data_len <= GTP1_HEADER_SIZE_LONG) {
+ p->rc = GTP_RC_TINY;
+ p->header_len = GTP1_HEADER_SIZE_SHORT;
+ return;
+ }
+
+ /* Check packet length field versus length of packet */
+ if (p->data_len != (ntoh16(pheader->length) + GTP1_HEADER_SIZE_SHORT)) {
+ LOGERR("GTP packet length field (%d + %d) does not match"
+ " actual length (%d)\n",
+ GTP1_HEADER_SIZE_SHORT, (int)ntoh16(pheader->length),
+ p->data_len);
+ p->rc = GTP_RC_TOOSHORT;
+ return;
+ }
+
+ p->rc = GTP_RC_PDU;
+ p->header_len = GTP1_HEADER_SIZE_LONG;
+}
+
+/* Examine whether p->data of size p->data_len has a valid GTP header. Set
+ * p->version, p->rc and p->header_len. On error, p->rc <= 0 (see enum
+ * gtp_rc). p->data must point at a buffer with p->data_len set. */
+void validate_gtp_header(struct gtp_packet_desc *p)
+{
+ p->rc = GTP_RC_UNKNOWN;
+
+ /* Need at least 1 byte in order to check version */
+ if (p->data_len < (1)) {
+ LOGERR("Discarding packet - too small\n");
+ p->rc = GTP_RC_TOOSHORT;
+ return;
+ }
+
+ p->version = p->data->flags >> 5;
+
+ switch (p->version) {
+ case 0:
+ validate_gtp0_header(p);
+ break;
+ case 1:
+ validate_gtp1_header(p);
+ break;
+ default:
+ LOGERR("Unsupported GTP version: %d\n", p->version);
+ p->rc = GTP_RC_UNSUPPORTED_VERSION;
+ break;
+ }
+}
+
+/* Validate header, and index information elements. Write decoded packet
+ * information to *res. res->data will point at the given data buffer. On
+ * error, p->rc is set <= 0 (see enum gtp_rc). */
+static void gtp_decode(const uint8_t *data, int data_len, struct gtp_packet_desc *res)
+{
+ memset(res, '\0', sizeof(*res));
+ res->data = (union gtp_packet*)data;
+ res->data_len = data_len;
+
+ validate_gtp_header(res);
+
+ if (res->rc == GTP_RC_TINY)
+ LOG("tiny: no IEs in this GTP packet\n");
+}
+
/* general */
@@ -55,6 +201,8 @@ const char* const gtphub_port_idx_names[GTPH_PORT_N] = {
};
+/* tei_map, tei_pool */
+
void tei_pool_init(struct tei_pool *pool)
{
*pool = (struct tei_pool){};
@@ -217,6 +365,17 @@ static int gtp_relay(struct osmo_fd *from,
/* insert magic here */
+ struct gtp_packet_desc p;
+ gtp_decode(buf, received, &p);
+
+ if (p.rc > 0)
+ LOG("Valid GTP header (v%d)\n", p.version);
+#if 0
+ else
+ // error has been logged
+ return 0;
+#endif
+
errno = 0;
ssize_t sent = sendto(to->fd, buf, received, 0,
(struct sockaddr*)to_addr, to_addr_len);
--
2.1.4