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Diffstat (limited to 'src/gprs/gprs_sndcp.c')
-rw-r--r-- | src/gprs/gprs_sndcp.c | 616 |
1 files changed, 616 insertions, 0 deletions
diff --git a/src/gprs/gprs_sndcp.c b/src/gprs/gprs_sndcp.c new file mode 100644 index 000000000..4f421e451 --- /dev/null +++ b/src/gprs/gprs_sndcp.c @@ -0,0 +1,616 @@ +/* GPRS SNDCP protocol implementation as per 3GPP TS 04.65 */ + +/* (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 Affero General Public License as published by + * the Free Software Foundation; either version 3 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 Affero General Public License for more details. + * + * You should have received a copy of the GNU Affero General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + * + */ + +#include <errno.h> +#include <stdint.h> + +#include <osmocore/msgb.h> +#include <osmocore/linuxlist.h> +#include <osmocore/timer.h> +#include <osmocore/talloc.h> + +#include <openbsc/gsm_data.h> +#include <openbsc/debug.h> +#include <openbsc/gprs_bssgp.h> +#include <openbsc/gprs_llc.h> +#include <openbsc/sgsn.h> + +#include "gprs_sndcp.h" + +/* Chapter 7.2: SN-PDU Formats */ +struct sndcp_common_hdr { + /* octet 1 */ + uint8_t nsapi:4; + uint8_t more:1; + uint8_t type:1; + uint8_t first:1; + uint8_t spare:1; +} __attribute__((packed)); + +/* PCOMP / DCOMP only exist in first fragment */ +struct sndcp_comp_hdr { + /* octet 2 */ + uint8_t pcomp:4; + uint8_t dcomp:4; +} __attribute__((packed)); + +struct sndcp_udata_hdr { + /* octet 3 */ + uint8_t npdu_high:4; + uint8_t seg_nr:4; + /* octet 4 */ + uint8_t npdu_low; +} __attribute__((packed)); + + +static void *tall_sndcp_ctx; + +/* A fragment queue entry, containing one framgent of a N-PDU */ +struct defrag_queue_entry { + struct llist_head list; + /* segment number of this fragment */ + uint32_t seg_nr; + /* length of the data area of this fragment */ + uint32_t data_len; + /* pointer to the data of this fragment */ + uint8_t *data; +}; + +LLIST_HEAD(gprs_sndcp_entities); + +/* Enqueue a fragment into the defragment queue */ +static int defrag_enqueue(struct gprs_sndcp_entity *sne, uint8_t seg_nr, + uint8_t *data, uint32_t data_len) +{ + struct defrag_queue_entry *dqe; + + dqe = talloc_zero(tall_sndcp_ctx, struct defrag_queue_entry); + if (!dqe) + return -ENOMEM; + dqe->data = talloc_zero_size(dqe, data_len); + if (!dqe->data) { + talloc_free(dqe); + return -ENOMEM; + } + dqe->seg_nr = seg_nr; + dqe->data_len = data_len; + + llist_add(&dqe->list, &sne->defrag.frag_list); + + if (seg_nr > sne->defrag.highest_seg) + sne->defrag.highest_seg = seg_nr; + + sne->defrag.seg_have |= (1 << seg_nr); + sne->defrag.tot_len += data_len; + + memcpy(dqe->data, data, data_len); + + return 0; +} + +/* return if we have all segments of this N-PDU */ +static int defrag_have_all_segments(struct gprs_sndcp_entity *sne) +{ + uint32_t seg_needed = 0; + unsigned int i; + + /* create a bitmask of needed segments */ + for (i = 0; i <= sne->defrag.highest_seg; i++) + seg_needed |= (1 << i); + + if (seg_needed == sne->defrag.seg_have) + return 1; + + return 0; +} + +static struct defrag_queue_entry *defrag_get_seg(struct gprs_sndcp_entity *sne, + uint32_t seg_nr) +{ + struct defrag_queue_entry *dqe; + + llist_for_each_entry(dqe, &sne->defrag.frag_list, list) { + if (dqe->seg_nr == seg_nr) { + llist_del(&dqe->list); + return dqe; + } + } + return NULL; +} + +/* Perform actual defragmentation and create an output packet */ +static int defrag_segments(struct gprs_sndcp_entity *sne) +{ + struct msgb *msg; + unsigned int seg_nr; + uint8_t *npdu; + + LOGP(DSNDCP, LOGL_DEBUG, "TLLI=0x%08x NSAPI=%u: Defragment output PDU %u " + "num_seg=%u tot_len=%u\n", sne->lle->llme->tlli, sne->nsapi, + sne->defrag.npdu, sne->defrag.highest_seg, sne->defrag.tot_len); + msg = msgb_alloc_headroom(sne->defrag.tot_len+256, 128, "SNDCP Defrag"); + if (!msg) + return -ENOMEM; + + /* FIXME: message headers + identifiers */ + + npdu = msg->data; + + for (seg_nr = 0; seg_nr <= sne->defrag.highest_seg; seg_nr++) { + struct defrag_queue_entry *dqe; + uint8_t *data; + + dqe = defrag_get_seg(sne, seg_nr); + if (!dqe) { + LOGP(DSNDCP, LOGL_ERROR, "Segment %u missing\n", seg_nr); + talloc_free(msg); + return -EIO; + } + /* actually append the segment to the N-PDU */ + data = msgb_put(msg, dqe->data_len); + memcpy(data, dqe->data, dqe->data_len); + + /* release memory for the fragment queue entry */ + talloc_free(dqe); + } + + /* FIXME: cancel timer */ + + /* actually send the N-PDU to the SGSN core code, which then + * hands it off to the correct GTP tunnel + GGSN via gtp_data_req() */ + return sgsn_rx_sndcp_ud_ind(&sne->ra_id, sne->lle->llme->tlli, + sne->nsapi, msg, sne->defrag.tot_len, npdu); +} + +static int defrag_input(struct gprs_sndcp_entity *sne, struct msgb *msg, uint8_t *hdr, + unsigned int len) +{ + struct sndcp_common_hdr *sch; + struct sndcp_comp_hdr *scomph = NULL; + struct sndcp_udata_hdr *suh; + uint16_t npdu_num; + uint8_t *data; + int rc; + + sch = (struct sndcp_common_hdr *) hdr; + if (sch->first) { + scomph = (struct sndcp_comp_hdr *) (hdr + 1); + suh = (struct sndcp_udata_hdr *) (hdr + 1 + sizeof(struct sndcp_common_hdr)); + } else + suh = (struct sndcp_udata_hdr *) (hdr + sizeof(struct sndcp_common_hdr)); + + data = (uint8_t *)suh + sizeof(struct sndcp_udata_hdr); + + npdu_num = (suh->npdu_high << 8) | suh->npdu_low; + + LOGP(DSNDCP, LOGL_DEBUG, "TLLI=0x%08x NSAPI=%u: Input PDU %u Segment %u " + "Length %u %s %s\n", sne->lle->llme->tlli, sne->nsapi, npdu_num, + suh->seg_nr, len, sch->first ? "F " : "", sch->more ? "M" : ""); + + if (sch->first) { + /* first segment of a new packet. Discard all leftover fragments of + * previous packet */ + if (!llist_empty(&sne->defrag.frag_list)) { + struct defrag_queue_entry *dqe, *dqe2; + LOGP(DSNDCP, LOGL_INFO, "TLLI=0x%08x NSAPI=%u: Dropping " + "SN-PDU %u due to insufficient segments (%04x)\n", + sne->lle->llme->tlli, sne->nsapi, sne->defrag.npdu, + sne->defrag.seg_have); + llist_for_each_entry_safe(dqe, dqe2, &sne->defrag.frag_list, list) { + llist_del(&dqe->list); + talloc_free(dqe); + } + } + /* store the currently de-fragmented PDU number */ + sne->defrag.npdu = npdu_num; + + /* Re-set fragmentation state */ + sne->defrag.no_more = sne->defrag.highest_seg = sne->defrag.seg_have = 0; + sne->defrag.tot_len = 0; + /* FIXME: (re)start timer */ + } + + if (sne->defrag.npdu != npdu_num) { + LOGP(DSNDCP, LOGL_INFO, "Segment for different SN-PDU " + "(%u != %u)\n", npdu_num, sne->defrag.npdu); + /* FIXME */ + } + + /* FIXME: check if seg_nr already exists */ + /* make sure to subtract length of SNDCP header from 'len' */ + rc = defrag_enqueue(sne, suh->seg_nr, data, len - (data - hdr)); + if (rc < 0) + return rc; + + if (!sch->more) { + /* this is suppsed to be the last segment of the N-PDU, but it + * might well be not the last to arrive */ + sne->defrag.no_more = 1; + } + + if (sne->defrag.no_more) { + /* we have already received the last segment before, let's check + * if all the previous segments exist */ + if (defrag_have_all_segments(sne)) + return defrag_segments(sne); + } + + return 0; +} + +static struct gprs_sndcp_entity *gprs_sndcp_entity_by_lle(const struct gprs_llc_lle *lle, + uint8_t nsapi) +{ + struct gprs_sndcp_entity *sne; + + llist_for_each_entry(sne, &gprs_sndcp_entities, list) { + if (sne->lle == lle && sne->nsapi == nsapi) + return sne; + } + return NULL; +} + +static struct gprs_sndcp_entity *gprs_sndcp_entity_alloc(struct gprs_llc_lle *lle, + uint8_t nsapi) +{ + struct gprs_sndcp_entity *sne; + + sne = talloc_zero(tall_sndcp_ctx, struct gprs_sndcp_entity); + if (!sne) + return NULL; + + sne->lle = lle; + sne->nsapi = nsapi; + sne->defrag.timer.data = sne; + //sne->fqueue.timer.cb = FIXME; + sne->rx_state = SNDCP_RX_S_FIRST; + INIT_LLIST_HEAD(&sne->defrag.frag_list); + + llist_add(&sne->list, &gprs_sndcp_entities); + + return sne; +} + +/* Entry point for the SNSM-ACTIVATE.indication */ +int sndcp_sm_activate_ind(struct gprs_llc_lle *lle, uint8_t nsapi) +{ + LOGP(DSNDCP, LOGL_INFO, "SNSM-ACTIVATE.ind (lle=%p TLLI=%08x, " + "SAPI=%u, NSAPI=%u)\n", lle, lle->llme->tlli, lle->sapi, nsapi); + + if (gprs_sndcp_entity_by_lle(lle, nsapi)) { + LOGP(DSNDCP, LOGL_ERROR, "Trying to ACTIVATE " + "already-existing entity (TLLI=%08x, NSAPI=%u)\n", + lle->llme->tlli, nsapi); + return -EEXIST; + } + + if (!gprs_sndcp_entity_alloc(lle, nsapi)) { + LOGP(DSNDCP, LOGL_ERROR, "Out of memory during ACTIVATE\n"); + return -ENOMEM; + } + + return 0; +} + +/* Entry point for the SNSM-DEACTIVATE.indication */ +int sndcp_sm_deactivate_ind(struct gprs_llc_lle *lle, uint8_t nsapi) +{ + struct gprs_sndcp_entity *sne; + + LOGP(DSNDCP, LOGL_INFO, "SNSM-DEACTIVATE.ind (lle=%p, TLLI=%08x, " + "SAPI=%u, NSAPI=%u)\n", lle, lle->llme->tlli, lle->sapi, nsapi); + + sne = gprs_sndcp_entity_by_lle(lle, nsapi); + if (!sne) { + LOGP(DSNDCP, LOGL_ERROR, "SNSM-DEACTIVATE.ind for non-" + "existing TLLI=%08x SAPI=%u NSAPI=%u\n", lle->llme->tlli, + lle->sapi, nsapi); + return -ENOENT; + } + llist_del(&sne->list); + /* frag queue entries are hierarchically allocated, so no need to + * free them explicitly here */ + talloc_free(sne); + + return 0; +} + +/* Fragmenter state */ +struct sndcp_frag_state { + uint8_t frag_nr; + struct msgb *msg; /* original message */ + uint8_t *next_byte; /* first byte of next fragment */ + + struct gprs_sndcp_entity *sne; + void *mmcontext; +}; + +/* returns '1' if there are more fragments to send, '0' if none */ +static int sndcp_send_ud_frag(struct sndcp_frag_state *fs) +{ + struct gprs_sndcp_entity *sne = fs->sne; + struct gprs_llc_lle *lle = sne->lle; + struct sndcp_common_hdr *sch; + struct sndcp_comp_hdr *scomph; + struct sndcp_udata_hdr *suh; + struct msgb *fmsg; + unsigned int max_payload_len; + unsigned int len; + uint8_t *data; + int rc, more; + + fmsg = msgb_alloc_headroom(fs->sne->lle->params.n201_u+256, 128, + "SNDCP Frag"); + if (!fmsg) + return -ENOMEM; + + /* make sure lower layers route the fragment like the original */ + msgb_tlli(fmsg) = msgb_tlli(fs->msg); + msgb_bvci(fmsg) = msgb_bvci(fs->msg); + msgb_nsei(fmsg) = msgb_nsei(fs->msg); + + /* prepend common SNDCP header */ + sch = (struct sndcp_common_hdr *) msgb_put(fmsg, sizeof(*sch)); + sch->nsapi = sne->nsapi; + /* Set FIRST bit if we are the first fragment in a series */ + if (fs->frag_nr == 0) + sch->first = 1; + sch->type = 1; + + /* append the compression header for first fragment */ + if (sch->first) { + scomph = (struct sndcp_comp_hdr *) + msgb_put(fmsg, sizeof(*scomph)); + scomph->pcomp = 0; + scomph->dcomp = 0; + } + + /* append the user-data header */ + suh = (struct sndcp_udata_hdr *) msgb_put(fmsg, sizeof(*suh)); + suh->npdu_low = sne->tx_npdu_nr & 0xff; + suh->npdu_high = (sne->tx_npdu_nr >> 8) & 0xf; + suh->seg_nr = fs->frag_nr % 0xf; + + /* calculate remaining length to be sent */ + len = (fs->msg->data + fs->msg->len) - fs->next_byte; + /* how much payload can we actually send via LLC? */ + max_payload_len = lle->params.n201_u - (sizeof(*sch) + sizeof(*suh)); + if (sch->first) + max_payload_len -= sizeof(*scomph); + /* check if we're exceeding the max */ + if (len > max_payload_len) + len = max_payload_len; + + /* copy the actual fragment data into our fmsg */ + data = msgb_put(fmsg, len); + memcpy(data, fs->next_byte, len); + + /* Increment fragment number and data pointer to next fragment */ + fs->frag_nr++; + fs->next_byte += len; + + /* determine if we have more fragemnts to send */ + if ((fs->msg->data + fs->msg->len) <= fs->next_byte) + more = 0; + else + more = 1; + + /* set the MORE bit of the SNDCP header accordingly */ + sch->more = more; + + rc = gprs_llc_tx_ui(fmsg, lle->sapi, 0, fs->mmcontext); + if (rc < 0) { + /* abort in case of error, do not advance frag_nr / next_byte */ + msgb_free(fmsg); + return rc; + } + + if (!more) { + /* we've sent all fragments */ + msgb_free(fs->msg); + memset(fs, 0, sizeof(*fs)); + /* increment NPDU number for next frame */ + sne->tx_npdu_nr = (sne->tx_npdu_nr + 1) % 0xfff; + return 0; + } + + /* default: more fragments to send */ + return 1; +} + +/* Request transmission of a SN-PDU over specified LLC Entity + SAPI */ +int sndcp_unitdata_req(struct msgb *msg, struct gprs_llc_lle *lle, uint8_t nsapi, + void *mmcontext) +{ + struct gprs_sndcp_entity *sne; + struct sndcp_common_hdr *sch; + struct sndcp_comp_hdr *scomph; + struct sndcp_udata_hdr *suh; + struct sndcp_frag_state fs; + + /* Identifiers from UP: (TLLI, SAPI) + (BVCI, NSEI) */ + + sne = gprs_sndcp_entity_by_lle(lle, nsapi); + if (!sne) { + LOGP(DSNDCP, LOGL_ERROR, "Cannot find SNDCP Entity\n"); + return -EIO; + } + + /* Check if we need to fragment this N-PDU into multiple SN-PDUs */ + if (msg->len > lle->params.n201_u - + (sizeof(*sch) + sizeof(*suh) + sizeof(*scomph))) { + /* initialize the fragmenter state */ + fs.msg = msg; + fs.frag_nr = 0; + fs.next_byte = msg->data; + fs.sne = sne; + fs.mmcontext = mmcontext; + + /* call function to generate and send fragments until all + * of the N-PDU has been sent */ + while (1) { + int rc = sndcp_send_ud_frag(&fs); + if (rc == 0) + return 0; + if (rc < 0) + return rc; + } + /* not reached */ + return 0; + } + + /* this is the non-fragmenting case where we only build 1 SN-PDU */ + + /* prepend the user-data header */ + suh = (struct sndcp_udata_hdr *) msgb_push(msg, sizeof(*suh)); + suh->npdu_low = sne->tx_npdu_nr & 0xff; + suh->npdu_high = (sne->tx_npdu_nr >> 8) & 0xf; + suh->seg_nr = 0; + sne->tx_npdu_nr = (sne->tx_npdu_nr + 1) % 0xfff; + + scomph = (struct sndcp_comp_hdr *) msgb_push(msg, sizeof(*scomph)); + scomph->pcomp = 0; + scomph->dcomp = 0; + + /* prepend common SNDCP header */ + sch = (struct sndcp_common_hdr *) msgb_push(msg, sizeof(*sch)); + sch->first = 1; + sch->type = 1; + sch->nsapi = nsapi; + + return gprs_llc_tx_ui(msg, lle->sapi, 0, mmcontext); +} + +/* Section 5.1.2.17 LL-UNITDATA.ind */ +int sndcp_llunitdata_ind(struct msgb *msg, struct gprs_llc_lle *lle, + uint8_t *hdr, uint16_t len) +{ + struct gprs_sndcp_entity *sne; + struct sndcp_common_hdr *sch = (struct sndcp_common_hdr *)hdr; + struct sndcp_comp_hdr *scomph = NULL; + struct sndcp_udata_hdr *suh; + uint8_t *npdu; + uint16_t npdu_num; + int npdu_len; + + sch = (struct sndcp_common_hdr *) hdr; + if (sch->first) { + scomph = (struct sndcp_comp_hdr *) (hdr + 1); + suh = (struct sndcp_udata_hdr *) (hdr + 1 + sizeof(struct sndcp_common_hdr)); + } else + suh = (struct sndcp_udata_hdr *) (hdr + sizeof(struct sndcp_common_hdr)); + + if (sch->type == 0) { + LOGP(DSNDCP, LOGL_ERROR, "SN-DATA PDU at unitdata_ind() function\n"); + return -EINVAL; + } + + if (len < sizeof(*sch) + sizeof(*suh)) { + LOGP(DSNDCP, LOGL_ERROR, "SN-UNITDATA PDU too short (%u)\n", len); + return -EIO; + } + + sne = gprs_sndcp_entity_by_lle(lle, sch->nsapi); + if (!sne) { + LOGP(DSNDCP, LOGL_ERROR, "Message for non-existing SNDCP Entity " + "(lle=%p, TLLI=%08x, SAPI=%u, NSAPI=%u)\n", lle, + lle->llme->tlli, lle->sapi, sch->nsapi); + return -EIO; + } + /* FIXME: move this RA_ID up to the LLME or even higher */ + bssgp_parse_cell_id(&sne->ra_id, msgb_bcid(msg)); + + /* any non-first segment is by definition something to defragment + * as is any segment that tells us there are more segments */ + if (!sch->first || sch->more) + return defrag_input(sne, msg, hdr, len); + + if (scomph && (scomph->pcomp || scomph->dcomp)) { + LOGP(DSNDCP, LOGL_ERROR, "We don't support compression yet\n"); + return -EIO; + } + + npdu_num = (suh->npdu_high << 8) | suh->npdu_low; + npdu = (uint8_t *)suh + sizeof(*suh); + npdu_len = (msg->data + msg->len) - npdu; + if (npdu_len <= 0) { + LOGP(DSNDCP, LOGL_ERROR, "Short SNDCP N-PDU: %d\n", npdu_len); + return -EIO; + } + /* actually send the N-PDU to the SGSN core code, which then + * hands it off to the correct GTP tunnel + GGSN via gtp_data_req() */ + return sgsn_rx_sndcp_ud_ind(&sne->ra_id, lle->llme->tlli, sne->nsapi, msg, npdu_len, npdu); +} + +/* Section 5.1.2.1 LL-RESET.ind */ +static int sndcp_ll_reset_ind(struct gprs_sndcp_entity *se) +{ + /* treat all outstanding SNDCP-LLC request type primitives as not sent */ + /* reset all SNDCP XID parameters to default values */ +} + +static int sndcp_ll_status_ind() +{ + /* inform the SM sub-layer by means of SNSM-STATUS.req */ +} + +#if 0 +static struct sndcp_state_list {{ + uint32_t states; + unsigned int type; + int (*rout)(struct gprs_sndcp_entity *se, struct msgb *msg); +} sndcp_state_list[] = { + { ALL_STATES, + LL_RESET_IND, sndcp_ll_reset_ind }, + { ALL_STATES, + LL_ESTABLISH_IND, sndcp_ll_est_ind }, + { SBIT(SNDCP_S_EST_RQD), + LL_ESTABLISH_RESP, sndcp_ll_est_ind }, + { SBIT(SNDCP_S_EST_RQD), + LL_ESTABLISH_CONF, sndcp_ll_est_conf }, + { SBIT(SNDCP_S_ +}; + +static int sndcp_rx_llc_prim() +{ + case LL_ESTABLISH_REQ: + case LL_RELEASE_REQ: + case LL_XID_REQ: + case LL_DATA_REQ: + LL_UNITDATA_REQ, /* TLLI, SN-PDU, Ref, QoS, Radio Prio, Ciph */ + + switch (prim) { + case LL_RESET_IND: + case LL_ESTABLISH_IND: + case LL_ESTABLISH_RESP: + case LL_ESTABLISH_CONF: + case LL_RELEASE_IND: + case LL_RELEASE_CONF: + case LL_XID_IND: + case LL_XID_RESP: + case LL_XID_CONF: + case LL_DATA_IND: + case LL_DATA_CONF: + case LL_UNITDATA_IND: + case LL_STATUS_IND: +} +#endif |