GPRS: Introduce a GPRS Gb Proxy
The ida of the Gb proxy is to aggregate Gb links with a number of BSS
and then present all the BSSGP-VC's together inside one NS-VC to the
actual SGSN.
The code is not yet expected to be complete.
diff --git a/openbsc/src/gb_proxy.c b/openbsc/src/gb_proxy.c
new file mode 100644
index 0000000..77cc8ca
--- /dev/null
+++ b/openbsc/src/gb_proxy.c
@@ -0,0 +1,315 @@
+/* NS-over-IP proxy */
+
+/* (C) 2010 by Harald Welte <laforge@gnumonks.org>
+ * (C) 2010 by On Waves
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <getopt.h>
+#include <errno.h>
+#include <sys/fcntl.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#include <osmocore/talloc.h>
+#include <osmocore/select.h>
+
+#include <openbsc/signal.h>
+#include <openbsc/debug.h>
+#include <openbsc/gprs_ns.h>
+#include <openbsc/gprs_bssgp.h>
+
+struct gbprox_peer {
+ struct llist_head list;
+
+ /* NS-VC over which we send/receive data to this BVC */
+ struct gprs_nsvc *nsvc;
+
+ /* BVCI used for Point-to-Point to this peer */
+ uint16_t bvci;
+
+ /* Routeing Area that this peer is part of (raw 04.08 encoding) */
+ uint8_t ra[6];
+};
+
+/* Linked list of all Gb peers (except SGSN) */
+static LLIST_HEAD(gbprox_bts_peers);
+
+/* Pointer to the SGSN peer */
+struct gbprox_peer *gbprox_peer_sgsn;
+
+/* The NS protocol stack instance we're using */
+extern struct gprs_ns_inst *gbprox_nsi;
+
+/* Find the gbprox_peer by its BVCI */
+static struct gbprox_peer *peer_by_bvci(uint16_t bvci)
+{
+ struct gbprox_peer *peer;
+ llist_for_each_entry(peer, &gbprox_bts_peers, list) {
+ if (peer->bvci == bvci)
+ return peer;
+ }
+ return NULL;
+}
+
+static struct gbprox_peer *peer_by_nsvc(struct gprs_nsvc *nsvc)
+{
+ struct gbprox_peer *peer;
+ llist_for_each_entry(peer, &gbprox_bts_peers, list) {
+ if (peer->nsvc == nsvc)
+ return peer;
+ }
+ return NULL;
+}
+
+/* look-up a peer by its Routeing Area Code (RAC) */
+static struct gbprox_peer *peer_by_rac(uint8_t *ra)
+{
+ struct gbprox_peer *peer;
+ llist_for_each_entry(peer, &gbprox_bts_peers, list) {
+ if (!memcmp(&peer->ra, ra, 6))
+ return peer;
+ }
+ return NULL;
+}
+
+/* look-up a peer by its Location Area Code (LAC) */
+static struct gbprox_peer *peer_by_lac(uint8_t *la)
+{
+ struct gbprox_peer *peer;
+ llist_for_each_entry(peer, &gbprox_bts_peers, list) {
+ if (!memcmp(&peer->ra, la, 5))
+ return peer;
+ }
+ return NULL;
+}
+
+static struct gbprox_peer *peer_alloc(uint16_t bvci)
+{
+ struct gbprox_peer *peer;
+
+ peer = talloc_zero(tall_bsc_ctx, struct gbprox_peer);
+ if (!peer)
+ return NULL;
+
+ peer->bvci = bvci;
+ llist_add(&peer->list, &gbprox_bts_peers);
+
+ return peer;
+}
+
+static void peer_free(struct gbprox_peer *peer)
+{
+ llist_del(&peer->list);
+ talloc_free(peer);
+}
+
+/* feed a message down the NS-VC associated with the specified peer */
+static int gbprox_tx2peer(struct msgb *msg, struct gbprox_peer *peer,
+ uint16_t ns_bvci)
+{
+ msgb_bvci(msg) = ns_bvci;
+ msgb_nsei(msg) = peer->nsvc->nsei;
+
+ return gprs_ns_sendmsg(gbprox_nsi, msg);
+}
+
+/* Send a message to a peer identified by ptp_bvci but using ns_bvci
+ * in the NS hdr */
+static int gbprox_tx2bvci(struct msgb *msg, uint16_t ptp_bvci,
+ uint16_t ns_bvci)
+{
+ struct gbprox_peer *peer;
+
+ peer = peer_by_bvci(ptp_bvci);
+ if (!peer)
+ return -ENOENT;
+
+ return gbprox_tx2peer(msg, peer, ns_bvci);
+}
+
+/* Receive an incoming signalling message from a BSS-side NS-VC */
+static int gbprox_rx_sig_from_bss(struct msgb *msg, struct gprs_nsvc *nsvc,
+ uint16_t ns_bvci)
+{
+ struct bssgp_normal_hdr *bgph = (struct bssgp_normal_hdr *) msg->l3h;
+ struct tlv_parsed tp;
+ uint8_t pdu_type = bgph->pdu_type;
+ int data_len = msgb_l3len(msg) - sizeof(*bgph);
+ struct gbprox_peer *from_peer;
+
+ if (ns_bvci != 0) {
+ LOGP(DGPRS, LOGL_NOTICE, "BVCI %u not signalling\n", ns_bvci);
+ return -EINVAL;
+ }
+
+ /* we actually should never see those two for BVCI == 0, but double-check
+ * just to make sure */
+ if (pdu_type == BSSGP_PDUT_UL_UNITDATA ||
+ pdu_type == BSSGP_PDUT_DL_UNITDATA) {
+ LOGP(DGPRS, LOGL_NOTICE, "UNITDATA not allowed in signalling\n");
+ return -EINVAL;
+ }
+
+ bssgp_tlv_parse(&tp, bgph->data, data_len);
+
+ switch (pdu_type) {
+ case BSSGP_PDUT_SUSPEND:
+ case BSSGP_PDUT_RESUME:
+ /* RAC snooping for SUSPEND/RESUME */
+ if (!TLVP_PRESENT(&tp, BSSGP_IE_ROUTEING_AREA))
+ goto err_mand_ie;
+ from_peer = peer_by_nsvc(nsvc);
+ if (!from_peer)
+ goto err_no_peer;
+ memcpy(&from_peer->ra, TLVP_VAL(&tp, BSSGP_IE_ROUTEING_AREA),
+ sizeof(&from_peer->ra));
+ /* FIXME: This only supports one BSS per RA */
+ break;
+ }
+
+ /* Normally, we can simply pass on all signalling messages from BSS to SGSN */
+ return gbprox_tx2peer(msg, gbprox_peer_sgsn, ns_bvci);
+err_no_peer:
+err_mand_ie:
+ /* FIXME: do something */
+ ;
+}
+
+/* Receive paging request from SGSN, we need to relay to proper BSS */
+static int gbprox_rx_paging(struct msgb *msg, struct tlv_parsed *tp,
+ struct gprs_nsvc *nsvc, uint16_t ns_bvci)
+{
+ struct gbprox_peer *peer;
+
+ if (TLVP_PRESENT(tp, BSSGP_IE_BVCI)) {
+ uint16_t bvci = ntohs(*(uint16_t *)TLVP_VAL(tp, BSSGP_IE_BVCI));
+ return gbprox_tx2bvci(msg, bvci, ns_bvci);
+ } else if (TLVP_PRESENT(tp, BSSGP_IE_ROUTEING_AREA)) {
+ peer = peer_by_rac(TLVP_VAL(tp, BSSGP_IE_ROUTEING_AREA));
+ return gbprox_tx2peer(msg, peer, ns_bvci);
+ } else if (TLVP_PRESENT(tp, BSSGP_IE_LOCATION_AREA)) {
+ peer = peer_by_lac(TLVP_VAL(tp, BSSGP_IE_LOCATION_AREA));
+ return gbprox_tx2peer(msg, peer, ns_bvci);
+ } else
+ return -EINVAL;
+}
+
+/* Receive an incoming signalling message from the SGSN-side NS-VC */
+static int gbprox_rx_sig_from_sgsn(struct msgb *msg, struct gprs_nsvc *nsvc,
+ uint16_t ns_bvci)
+{
+ struct bssgp_normal_hdr *bgph = (struct bssgp_normal_hdr *) msg->l3h;
+ struct tlv_parsed tp;
+ uint8_t pdu_type = bgph->pdu_type;
+ int data_len = msgb_l3len(msg) - sizeof(*bgph);
+ struct gbprox_peer *peer;
+ uint16_t bvci;
+ int rc = 0;
+
+ if (ns_bvci != 0) {
+ LOGP(DGPRS, LOGL_NOTICE, "BVCI %u not signalling\n", ns_bvci);
+ return -EINVAL;
+ }
+
+ /* we actually should never see those two for BVCI == 0, but double-check
+ * just to make sure */
+ if (pdu_type == BSSGP_PDUT_UL_UNITDATA ||
+ pdu_type == BSSGP_PDUT_DL_UNITDATA) {
+ LOGP(DGPRS, LOGL_NOTICE, "UNITDATA not allowed in signalling\n");
+ return -EINVAL;
+ }
+
+ rc = bssgp_tlv_parse(&tp, bgph->data, data_len);
+
+ switch (pdu_type) {
+ case BSSGP_PDUT_FLUSH_LL:
+ case BSSGP_PDUT_BVC_BLOCK_ACK:
+ case BSSGP_PDUT_BVC_UNBLOCK_ACK:
+ case BSSGP_PDUT_BVC_RESET:
+ case BSSGP_PDUT_BVC_RESET_ACK:
+ /* simple case: BVCI IE is mandatory */
+ if (!TLVP_PRESENT(&tp, BSSGP_IE_BVCI))
+ goto err_mand_ie;
+ bvci = ntohs(*(uint16_t *)TLVP_VAL(&tp, BSSGP_IE_BVCI));
+ rc = gbprox_tx2bvci(msg, bvci, ns_bvci);
+ break;
+ case BSSGP_PDUT_PAGING_PS:
+ case BSSGP_PDUT_PAGING_CS:
+ /* process the paging request (LAC/RAC lookup) */
+ rc = gbprox_rx_paging(msg, &tp, nsvc, ns_bvci);
+ break;
+ case BSSGP_PDUT_STATUS:
+ /* FIXME: Some exception has occurred */
+ LOGP(DGPRS, LOGL_NOTICE, "STATUS not implemented yet\n");
+ break;
+ /* those only exist in the SGSN -> BSS direction */
+ case BSSGP_PDUT_SUSPEND_ACK:
+ case BSSGP_PDUT_SUSPEND_NACK:
+ case BSSGP_PDUT_RESUME_ACK:
+ case BSSGP_PDUT_RESUME_NACK:
+ /* RAC IE is mandatory */
+ if (!TLVP_PRESENT(&tp, BSSGP_IE_ROUTEING_AREA))
+ goto err_mand_ie;
+ peer = peer_by_rac(TLVP_VAL(&tp, BSSGP_IE_ROUTEING_AREA));
+ if (!peer)
+ goto err_no_peer;
+ rc = gbprox_tx2peer(msg, peer, ns_bvci);
+ break;
+ case BSSGP_PDUT_SGSN_INVOKE_TRACE:
+ LOGP(DGPRS, LOGL_ERROR, "SGSN INVOKE TRACE not supported\n");
+ break;
+ default:
+ DEBUGP(DGPRS, "BSSGP PDU type 0x%02x unknown\n", pdu_type);
+ break;
+ }
+
+ return rc;
+err_mand_ie:
+ ; /* FIXME: this would pull gprs_bssgp.c in, which in turn has dependencies */
+ //return bssgp_tx_status(BSSGP_CAUSE_MISSING_MAND_IE, NULL, msg);
+err_no_peer:
+ ; /* FIXME */
+}
+
+/* Main input function for Gb proxy */
+int gbprox_rcvmsg(struct msgb *msg, struct gprs_nsvc *nsvc, uint16_t ns_bvci)
+{
+ struct gbprox_peer *peer;
+
+ /* Only BVCI=0 messages need special treatment */
+ if (ns_bvci == 0 || ns_bvci == 1) {
+ if (nsvc->remote_end_is_sgsn)
+ return gbprox_rx_sig_from_sgsn(msg, nsvc, ns_bvci);
+ else
+ return gbprox_rx_sig_from_bss(msg, nsvc, ns_bvci);
+ }
+
+ /* All other BVCI are PTP and thus can be simply forwarded */
+ peer = peer_by_bvci(ns_bvci);
+ if (!peer) {
+ LOGP(DGPRS, LOGL_ERROR, "Couldn't find peer for BVCI %u\n", ns_bvci);
+ return -EIO;
+ }
+
+ return gbprox_tx2peer(msg, peer, ns_bvci);
+}