diff options
Diffstat (limited to 'openbsc/src/gprs/gb_proxy.c')
| -rw-r--r-- | openbsc/src/gprs/gb_proxy.c | 416 |
1 files changed, 416 insertions, 0 deletions
diff --git a/openbsc/src/gprs/gb_proxy.c b/openbsc/src/gprs/gb_proxy.c new file mode 100644 index 000000000..fe5ad702f --- /dev/null +++ b/openbsc/src/gprs/gb_proxy.c @@ -0,0 +1,416 @@ +/* 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> +#include <openbsc/gb_proxy.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); + +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(const 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(const 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); +} + +/* strip off the NS header */ +static void strip_ns_hdr(struct msgb *msg) +{ + int strip_len = msgb_bssgph(msg) - msg->data; + msgb_pull(msg, strip_len); +} + +/* FIXME: this is copy+paste from gprs_bssgp.c */ +static inline struct msgb *bssgp_msgb_alloc(void) +{ + return msgb_alloc_headroom(4096, 128, "BSSGP"); +} +static int bssgp_tx_simple_bvci(uint8_t pdu_type, uint16_t nsei, + uint16_t bvci, uint16_t ns_bvci) +{ + struct msgb *msg = bssgp_msgb_alloc(); + struct bssgp_normal_hdr *bgph = + (struct bssgp_normal_hdr *) msgb_put(msg, sizeof(*bgph)); + uint16_t _bvci; + + msgb_nsei(msg) = nsei; + msgb_bvci(msg) = ns_bvci; + + bgph->pdu_type = pdu_type; + _bvci = htons(bvci); + msgb_tvlv_put(msg, BSSGP_IE_BVCI, 2, (uint8_t *) &_bvci); + + return gprs_ns_sendmsg(gbprox_nsi, msg); +} + + +/* feed a message down the NS-VC associated with the specified peer */ +static int gbprox_relay2sgsn(struct msgb *msg, uint16_t ns_bvci) +{ + DEBUGP(DGPRS, "NSEI=%u proxying to SGSN (NS_BVCI=%u, NSEI=%u)\n", + msgb_nsei(msg), ns_bvci, gbcfg.nsip_sgsn_nsei); + + msgb_bvci(msg) = ns_bvci; + msgb_nsei(msg) = gbcfg.nsip_sgsn_nsei; + + strip_ns_hdr(msg); + + return gprs_ns_sendmsg(gbprox_nsi, msg); +} + +/* feed a message down the NS-VC associated with the specified peer */ +static int gbprox_relay2peer(struct msgb *msg, struct gbprox_peer *peer, + uint16_t ns_bvci) +{ + DEBUGP(DGPRS, "NSEI=%u proxying to BSS (NS_BVCI=%u, NSEI=%u)\n", + msgb_nsei(msg), ns_bvci, peer->nsvc->nsei); + + msgb_bvci(msg) = ns_bvci; + msgb_nsei(msg) = peer->nsvc->nsei; + + strip_ns_hdr(msg); + + 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_relay2bvci(struct msgb *msg, uint16_t ptp_bvci, + uint16_t ns_bvci) +{ + struct gbprox_peer *peer; + + peer = peer_by_bvci(ptp_bvci); + if (!peer) { + LOGP(DGPRS, LOGL_ERROR, "Cannot find BSS for BVCI %u\n", + ptp_bvci); + return -ENOENT; + } + + return gbprox_relay2peer(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 *) msgb_bssgph(msg); + struct tlv_parsed tp; + uint8_t pdu_type = bgph->pdu_type; + int data_len = msgb_bssgp_len(msg) - sizeof(*bgph); + struct gbprox_peer *from_peer; + struct gprs_ra_id raid; + + if (ns_bvci != 0) { + LOGP(DGPRS, LOGL_NOTICE, "NSEI=%u BVCI %u is not signalling\n", + nsvc->nsei, 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, "NSEI=%u UNITDATA not allowed in " + "signalling\n", nsvc->nsei); + return -EINVAL; + } + + bssgp_tlv_parse(&tp, bgph->data, data_len); + + switch (pdu_type) { + case BSSGP_PDUT_SUSPEND: + case BSSGP_PDUT_RESUME: + /* We implement RAC snooping during SUSPEND/RESUME, since + * it establishes a relationsip between BVCI/peer and the + * routeing area code. The snooped information is then + * used for routing the {SUSPEND,RESUME}_[N]ACK back to + * the correct BSSGP */ + 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)); + gsm48_parse_ra(&raid, &from_peer->ra); + DEBUGP(DGPRS, "NSEI=%u RAC snooping: RAC %u/%u/%u/%u behind BVCI=%u, " + "NSVCI=%u\n", nsvc->nsei, raid.mcc, raid.mnc, raid.lac, + raid.rac , from_peer->bvci, nsvc->nsvci); + /* FIXME: This only supports one BSS per RA */ + break; + case BSSGP_PDUT_BVC_RESET: + /* If we receive a BVC reset on the signalling endpoint, we + * don't want the SGSN to reset, as the signalling endpoint + * is common for all point-to-point BVCs (and thus all BTS) */ + if (TLVP_PRESENT(&tp, BSSGP_IE_BVCI)) { + uint16_t bvci = ntohs(*(uint16_t *)TLVP_VAL(&tp, BSSGP_IE_BVCI)); + if (bvci == 0) { + /* FIXME: only do this if SGSN is alive! */ + LOGP(DGPRS, LOGL_INFO, "NSEI=%u Sending fake " + "BVC RESET ACK of BVCI=0\n", nsvc->nsei); + return bssgp_tx_simple_bvci(BSSGP_PDUT_BVC_RESET_ACK, + nsvc->nsei, 0, ns_bvci); + } else if (!peer_by_bvci(bvci)) { + /* if a PTP-BVC is reset, and we don't know that + * PTP-BVCI yet, we should allocate a new peer */ + LOGP(DGPRS, LOGL_INFO, "Allocationg new peer for " + "BVCI=%u via NSVCI=%u/NSEI=%u\n", bvci, + nsvc->nsvci, nsvc->nsei); + from_peer = peer_alloc(bvci); + from_peer->nsvc = nsvc; + } + } + break; + } + + /* Normally, we can simply pass on all signalling messages from BSS to SGSN */ + return gbprox_relay2sgsn(msg, 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_relay2bvci(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_relay2peer(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_relay2peer(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 *) msgb_bssgph(msg); + struct tlv_parsed tp; + uint8_t pdu_type = bgph->pdu_type; + int data_len = msgb_bssgp_len(msg) - sizeof(*bgph); + struct gbprox_peer *peer; + uint16_t bvci; + int rc = 0; + + if (ns_bvci != 0) { + LOGP(DGPRS, LOGL_NOTICE, "NSEI=%u(SGSN) BVCI %u is not " + "signalling\n", nsvc->nsei, 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, "NSEI=%u(SGSN) UNITDATA not allowed in " + "signalling\n", nsvc->nsei); + 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_relay2bvci(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, + "NSEI=%u(SGSN) STATUS not implemented yet\n", nsvc->nsei); + 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_relay2peer(msg, peer, ns_bvci); + break; + case BSSGP_PDUT_SGSN_INVOKE_TRACE: + LOGP(DGPRS, LOGL_ERROR, + "NSEI=%u(SGSN) INVOKE TRACE not supported\n", nsvc->nsei); + break; + default: + DEBUGP(DGPRS, "BSSGP PDU type 0x%02x unknown\n", pdu_type); + break; + } + + return rc; +err_mand_ie: + LOGP(DGPRS, LOGL_ERROR, "NSEI=%u(SGSN) missing mandatory IE\n", + nsvc->nsei); + /* FIXME: this would pull gprs_bssgp.c in, which in turn has dependencies */ + //return bssgp_tx_status(BSSGP_CAUSE_MISSING_MAND_IE, NULL, msg); + return; +err_no_peer: + LOGP(DGPRS, LOGL_ERROR, "NSEI=%u(SGSN) cannot find peer based on RAC\n"); + /* FIXME */ + return; +} + +/* Main input function for Gb proxy */ +int gbprox_rcvmsg(struct msgb *msg, struct gprs_nsvc *nsvc, uint16_t ns_bvci) +{ + int rc; + + /* Only BVCI=0 messages need special treatment */ + if (ns_bvci == 0 || ns_bvci == 1) { + if (nsvc->remote_end_is_sgsn) + rc = gbprox_rx_sig_from_sgsn(msg, nsvc, ns_bvci); + else + rc = gbprox_rx_sig_from_bss(msg, nsvc, ns_bvci); + } else { + /* All other BVCI are PTP and thus can be simply forwarded */ + if (!nsvc->remote_end_is_sgsn) { + rc = gbprox_relay2sgsn(msg, ns_bvci); + } else { + struct gbprox_peer *peer = peer_by_bvci(ns_bvci); + if (!peer) { + LOGP(DGPRS, LOGL_NOTICE, "Allocationg new peer for " + "BVCI=%u via NSVC=%u/NSEI=%u\n", ns_bvci, + nsvc->nsvci, nsvc->nsei); + peer = peer_alloc(ns_bvci); + peer->nsvc = nsvc; + } + rc = gbprox_relay2peer(msg, peer, ns_bvci); + } + } + + return rc; +} |