Pablo Neira Ayuso | 0ba77d5 | 2011-06-05 18:32:44 +0200 | [diff] [blame] | 1 | /* OpenBSC minimal LAPD implementation */ |
| 2 | |
| 3 | /* (C) 2009 by oystein@homelien.no |
| 4 | * (C) 2009 by Holger Hans Peter Freyther <zecke@selfish.org> |
| 5 | * (C) 2010 by Digium and Matthew Fredrickson <creslin@digium.com> |
| 6 | * (C) 2011 by Harald Welte <laforge@gnumonks.org> |
| 7 | * |
| 8 | * All Rights Reserved |
| 9 | * |
| 10 | * This program is free software; you can redistribute it and/or modify |
| 11 | * it under the terms of the GNU General Public License as published by |
| 12 | * the Free Software Foundation; either version 2 of the License, or |
| 13 | * (at your option) any later version. |
| 14 | * |
| 15 | * This program is distributed in the hope that it will be useful, |
| 16 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 17 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 18 | * GNU General Public License for more details. |
| 19 | * |
| 20 | * You should have received a copy of the GNU General Public License along |
| 21 | * with this program; if not, write to the Free Software Foundation, Inc., |
| 22 | * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. |
| 23 | * |
| 24 | */ |
| 25 | |
| 26 | /* TODO: |
| 27 | * detect RR timeout and set SAP state back to SABM_RETRANSMIT |
| 28 | * use of value_string |
| 29 | * further code cleanup (spaghetti) |
| 30 | */ |
| 31 | |
| 32 | #include "internal.h" |
| 33 | |
| 34 | #include <stdio.h> |
| 35 | #include <string.h> |
| 36 | #include <assert.h> |
| 37 | #include <errno.h> |
| 38 | |
| 39 | #include "lapd.h" |
| 40 | |
| 41 | #include <osmocom/core/linuxlist.h> |
| 42 | #include <osmocom/core/logging.h> |
| 43 | #include <talloc.h> |
| 44 | #include <osmocom/core/msgb.h> |
| 45 | #include <osmocom/core/timer.h> |
Pablo Neira Ayuso | 0b099b2 | 2011-06-09 13:14:11 +0200 | [diff] [blame^] | 46 | #include <osmocom/abis/logging.h> |
Pablo Neira Ayuso | 0ba77d5 | 2011-06-05 18:32:44 +0200 | [diff] [blame] | 47 | |
| 48 | #define SABM_INTERVAL 0, 300000 |
| 49 | |
| 50 | typedef enum { |
| 51 | LAPD_TEI_NONE = 0, |
| 52 | LAPD_TEI_ASSIGNED, |
| 53 | LAPD_TEI_ACTIVE, |
| 54 | } lapd_tei_state; |
| 55 | |
| 56 | const char *lapd_tei_states[] = { |
| 57 | "NONE", |
| 58 | "ASSIGNED", |
| 59 | "ACTIVE", |
| 60 | }; |
| 61 | |
| 62 | typedef enum { |
| 63 | LAPD_TYPE_NONE = 0, |
| 64 | |
| 65 | LAPD_TYPE_I, |
| 66 | LAPD_TYPE_S, |
| 67 | LAPD_TYPE_U, |
| 68 | } lapd_msg_type; |
| 69 | |
| 70 | typedef enum { |
| 71 | /* commands/responses */ |
| 72 | LAPD_CMD_NONE = 0, |
| 73 | |
| 74 | LAPD_CMD_I, |
| 75 | LAPD_CMD_RR, |
| 76 | LAPD_CMD_RNR, |
| 77 | LAPD_CMD_REJ, |
| 78 | |
| 79 | LAPD_CMD_SABME, |
| 80 | LAPD_CMD_DM, |
| 81 | LAPD_CMD_UI, |
| 82 | LAPD_CMD_DISC, |
| 83 | LAPD_CMD_UA, |
| 84 | LAPD_CMD_FRMR, |
| 85 | LAPD_CMD_XID, |
| 86 | } lapd_cmd_type; |
| 87 | |
| 88 | const char *lapd_cmd_types[] = { |
| 89 | "NONE", |
| 90 | |
| 91 | "I", |
| 92 | "RR", |
| 93 | "RNR", |
| 94 | "REJ", |
| 95 | |
| 96 | "SABME", |
| 97 | "DM", |
| 98 | "UI", |
| 99 | "DISC", |
| 100 | "UA", |
| 101 | "FRMR", |
| 102 | "XID", |
| 103 | |
| 104 | }; |
| 105 | |
| 106 | enum lapd_sap_state { |
| 107 | SAP_STATE_INACTIVE, |
| 108 | SAP_STATE_SABM_RETRANS, |
| 109 | SAP_STATE_ACTIVE, |
| 110 | }; |
| 111 | |
| 112 | const char *lapd_sap_states[] = { |
| 113 | "INACTIVE", |
| 114 | "SABM_RETRANS", |
| 115 | "ACTIVE", |
| 116 | }; |
| 117 | |
| 118 | const char *lapd_msg_types = "?ISU"; |
| 119 | |
| 120 | /* structure representing an allocated TEI within a LAPD instance */ |
| 121 | struct lapd_tei { |
| 122 | struct llist_head list; |
| 123 | struct lapd_instance *li; |
| 124 | uint8_t tei; |
| 125 | lapd_tei_state state; |
| 126 | |
| 127 | struct llist_head sap_list; |
| 128 | }; |
| 129 | |
| 130 | /* Structure representing a SAP within a TEI. We use this for TE-mode to |
| 131 | * re-transmit SABM */ |
| 132 | struct lapd_sap { |
| 133 | struct llist_head list; |
| 134 | struct lapd_tei *tei; |
| 135 | uint8_t sapi; |
| 136 | enum lapd_sap_state state; |
| 137 | |
| 138 | /* A valid N(R) value is one that is in the range V(A) ≤ N(R) ≤ V(S). */ |
| 139 | int vs; /* next to be transmitted */ |
| 140 | int va; /* last acked by peer */ |
| 141 | int vr; /* next expected to be received */ |
| 142 | |
| 143 | struct osmo_timer_list sabme_timer; /* timer to re-transmit SABM message */ |
| 144 | }; |
| 145 | |
| 146 | /* 3.5.2.2 Send state variable V(S) |
| 147 | * Each point-to-point data link connection endpoint shall have an associated V(S) when using I frame |
| 148 | * commands. V(S) denotes the sequence number of the next I frame to be transmitted. The V(S) can |
| 149 | * take on the value 0 through n minus 1. The value of V(S) shall be incremented by 1 with each |
| 150 | * successive I frame transmission, and shall not exceed V(A) by more than the maximum number of |
| 151 | * outstanding I frames k. The value of k may be in the range of 1 ≤ k ≤ 127. |
| 152 | * |
| 153 | * 3.5.2.3 Acknowledge state variable V(A) |
| 154 | * Each point-to-point data link connection endpoint shall have an associated V(A) when using I frame |
| 155 | * commands and supervisory frame commands/responses. V(A) identifies the last I frame that has been |
| 156 | * acknowledged by its peer [V(A) − 1 equals the N(S) of the last acknowledged I frame]. V(A) can |
| 157 | * take on the value 0 through n minus 1. The value of V(A) shall be updated by the valid N(R) values |
| 158 | * received from its peer (see 3.5.2.6). A valid N(R) value is one that is in the range V(A) ≤ N(R) ≤ |
| 159 | * V(S). |
| 160 | * |
| 161 | * 3.5.2.5 Receive state variable V(R) |
| 162 | * Each point-to-point data link connection endpoint shall have an associated V(R) when using I frame |
| 163 | * commands and supervisory frame commands/responses. V(R) denotes the sequence number of the |
| 164 | * next in-sequence I frame expected to be received. V(R) can take on the value 0 through n minus 1. |
| 165 | * The value of V(R) shall be incremented by one with the receipt of an error-free, in-sequence I frame |
| 166 | * whose N(S) equals V(R). |
| 167 | */ |
| 168 | #define LAPD_NS(sap) (sap->vs) |
| 169 | #define LAPD_NR(sap) (sap->vr) |
| 170 | |
| 171 | /* 3.5.2.4 Send sequence number N(S) |
| 172 | * Only I frames contain N(S), the send sequence number of transmitted I frames. At the time that an in- |
| 173 | * sequence I frame is designated for transmission, the value of N(S) is set equal to V(S). |
| 174 | * |
| 175 | * 3.5.2.6 Receive sequence number N(R) |
| 176 | * All I frames and supervisory frames contain N(R), the expected send sequence number of the next |
| 177 | * received I frame. At the time that a frame of the above types is designated for transmission, the value |
| 178 | * of N(R) is set equal to V(R). N(R) indicates that the data link layer entity transmitting the N(R) has |
| 179 | * correctly received all I frames numbered up to and including N(R) − 1. |
| 180 | */ |
| 181 | |
| 182 | /* Resolve TEI structure from given numeric TEI */ |
| 183 | static struct lapd_tei *teip_from_tei(struct lapd_instance *li, uint8_t tei) |
| 184 | { |
| 185 | struct lapd_tei *lt; |
| 186 | |
| 187 | llist_for_each_entry(lt, &li->tei_list, list) { |
| 188 | if (lt->tei == tei) |
| 189 | return lt; |
| 190 | } |
| 191 | return NULL; |
| 192 | }; |
| 193 | |
| 194 | static void lapd_tei_set_state(struct lapd_tei *teip, int newstate) |
| 195 | { |
| 196 | DEBUGP(DMI, "state change on TEI %d: %s -> %s\n", teip->tei, |
| 197 | lapd_tei_states[teip->state], lapd_tei_states[newstate]); |
| 198 | teip->state = newstate; |
| 199 | }; |
| 200 | |
| 201 | /* Allocate a new TEI */ |
| 202 | struct lapd_tei *lapd_tei_alloc(struct lapd_instance *li, uint8_t tei) |
| 203 | { |
| 204 | struct lapd_tei *teip; |
| 205 | |
| 206 | teip = talloc_zero(li, struct lapd_tei); |
| 207 | if (!teip) |
| 208 | return NULL; |
| 209 | |
| 210 | teip->li = li; |
| 211 | teip->tei = tei; |
| 212 | llist_add(&teip->list, &li->tei_list); |
| 213 | INIT_LLIST_HEAD(&teip->sap_list); |
| 214 | |
| 215 | lapd_tei_set_state(teip, LAPD_TEI_ASSIGNED); |
| 216 | |
| 217 | return teip; |
| 218 | } |
| 219 | |
| 220 | /* Find a SAP within a given TEI */ |
| 221 | static struct lapd_sap *lapd_sap_find(struct lapd_tei *teip, uint8_t sapi) |
| 222 | { |
| 223 | struct lapd_sap *sap; |
| 224 | |
| 225 | llist_for_each_entry(sap, &teip->sap_list, list) { |
| 226 | if (sap->sapi == sapi) |
| 227 | return sap; |
| 228 | } |
| 229 | |
| 230 | return NULL; |
| 231 | } |
| 232 | |
| 233 | static void sabme_timer_cb(void *_sap); |
| 234 | |
| 235 | /* Allocate a new SAP within a given TEI */ |
| 236 | static struct lapd_sap *lapd_sap_alloc(struct lapd_tei *teip, uint8_t sapi) |
| 237 | { |
| 238 | struct lapd_sap *sap = talloc_zero(teip, struct lapd_sap); |
| 239 | |
| 240 | LOGP(DMI, LOGL_INFO, "Allocating SAP for SAPI=%u / TEI=%u\n", |
| 241 | sapi, teip->tei); |
| 242 | |
| 243 | sap->sapi = sapi; |
| 244 | sap->tei = teip; |
| 245 | sap->sabme_timer.cb = &sabme_timer_cb; |
| 246 | sap->sabme_timer.data = sap; |
| 247 | |
| 248 | llist_add(&sap->list, &teip->sap_list); |
| 249 | |
| 250 | return sap; |
| 251 | } |
| 252 | |
| 253 | static void lapd_sap_set_state(struct lapd_tei *teip, uint8_t sapi, |
| 254 | enum lapd_sap_state newstate) |
| 255 | { |
| 256 | struct lapd_sap *sap = lapd_sap_find(teip, sapi); |
| 257 | if (!sap) |
| 258 | return; |
| 259 | |
| 260 | DEBUGP(DMI, "state change on TEI %u / SAPI %u: %s -> %s\n", teip->tei, |
| 261 | sapi, lapd_sap_states[sap->state], lapd_sap_states[newstate]); |
| 262 | switch (sap->state) { |
| 263 | case SAP_STATE_SABM_RETRANS: |
| 264 | if (newstate != SAP_STATE_SABM_RETRANS) |
| 265 | osmo_timer_del(&sap->sabme_timer); |
| 266 | break; |
| 267 | default: |
| 268 | if (newstate == SAP_STATE_SABM_RETRANS) |
| 269 | osmo_timer_schedule(&sap->sabme_timer, SABM_INTERVAL); |
| 270 | break; |
| 271 | } |
| 272 | |
| 273 | sap->state = newstate; |
| 274 | }; |
| 275 | |
| 276 | /* Input function into TEI manager */ |
| 277 | static void lapd_tei_receive(struct lapd_instance *li, uint8_t *data, int len) |
| 278 | { |
| 279 | uint8_t entity = data[0]; |
| 280 | uint8_t ref = data[1]; |
| 281 | uint8_t mt = data[3]; |
| 282 | uint8_t action = data[4] >> 1; |
| 283 | uint8_t e = data[4] & 1; |
| 284 | uint8_t resp[8]; |
| 285 | struct lapd_tei *teip; |
| 286 | |
| 287 | DEBUGP(DMI, "TEIMGR: entity %x, ref %x, mt %x, action %x, e %x\n", entity, ref, mt, action, e); |
| 288 | |
| 289 | switch (mt) { |
| 290 | case 0x01: /* IDENTITY REQUEST */ |
| 291 | DEBUGP(DMI, "TEIMGR: identity request for TEI %u\n", action); |
| 292 | |
| 293 | teip = teip_from_tei(li, action); |
| 294 | if (!teip) { |
| 295 | LOGP(DMI, LOGL_INFO, "TEI MGR: New TEI %u\n", action); |
| 296 | teip = lapd_tei_alloc(li, action); |
| 297 | } |
| 298 | |
| 299 | /* Send ACCEPT */ |
| 300 | memmove(resp, "\xfe\xff\x03\x0f\x00\x00\x02\x00", 8); |
| 301 | resp[7] = (action << 1) | 1; |
| 302 | li->transmit_cb(resp, 8, li->cbdata); |
| 303 | |
| 304 | if (teip->state == LAPD_TEI_NONE) |
| 305 | lapd_tei_set_state(teip, LAPD_TEI_ASSIGNED); |
| 306 | break; |
| 307 | default: |
| 308 | LOGP(DMI, LOGL_NOTICE, "TEIMGR: unknown mt %x action %x\n", |
| 309 | mt, action); |
| 310 | break; |
| 311 | }; |
| 312 | }; |
| 313 | |
| 314 | /* General input function for any data received for this LAPD instance */ |
| 315 | uint8_t *lapd_receive(struct lapd_instance *li, uint8_t * data, unsigned int len, |
| 316 | int *ilen, lapd_mph_type *prim) |
| 317 | { |
| 318 | uint8_t sapi, cr, tei, command; |
| 319 | int pf, ns, nr; |
| 320 | uint8_t *contents; |
| 321 | struct lapd_tei *teip; |
| 322 | struct lapd_sap *sap; |
| 323 | |
| 324 | uint8_t resp[8]; |
| 325 | int l = 0; |
| 326 | |
| 327 | *ilen = 0; |
| 328 | *prim = 0; |
| 329 | |
| 330 | if (len < 2) { |
| 331 | DEBUGP(DMI, "len %d < 2\n", len); |
| 332 | return NULL; |
| 333 | }; |
| 334 | |
| 335 | if ((data[0] & 1) != 0 || (data[1] & 1) != 1) { |
| 336 | DEBUGP(DMI, "address field %x/%x not well formed\n", data[0], |
| 337 | data[1]); |
| 338 | return NULL; |
| 339 | }; |
| 340 | |
| 341 | sapi = data[0] >> 2; |
| 342 | cr = (data[0] >> 1) & 1; |
| 343 | tei = data[1] >> 1; |
| 344 | command = li->network_side ^ cr; |
| 345 | //DEBUGP(DMI, " address sapi %x tei %d cmd %d cr %d\n", sapi, tei, command, cr); |
| 346 | |
| 347 | if (len < 3) { |
| 348 | DEBUGP(DMI, "len %d < 3\n", len); |
| 349 | return NULL; |
| 350 | }; |
| 351 | |
| 352 | lapd_msg_type typ = 0; |
| 353 | lapd_cmd_type cmd = 0; |
| 354 | pf = -1; |
| 355 | ns = -1; |
| 356 | nr = -1; |
| 357 | if ((data[2] & 1) == 0) { |
| 358 | typ = LAPD_TYPE_I; |
| 359 | assert(len >= 4); |
| 360 | ns = data[2] >> 1; |
| 361 | nr = data[3] >> 1; |
| 362 | pf = data[3] & 1; |
| 363 | cmd = LAPD_CMD_I; |
| 364 | } else if ((data[2] & 3) == 1) { |
| 365 | typ = LAPD_TYPE_S; |
| 366 | assert(len >= 4); |
| 367 | nr = data[3] >> 1; |
| 368 | pf = data[3] & 1; |
| 369 | switch (data[2]) { |
| 370 | case 0x1: |
| 371 | cmd = LAPD_CMD_RR; |
| 372 | break; |
| 373 | case 0x5: |
| 374 | cmd = LAPD_CMD_RNR; |
| 375 | break; |
| 376 | case 0x9: |
| 377 | cmd = LAPD_CMD_REJ; |
| 378 | break; |
| 379 | default: |
| 380 | LOGP(DMI, LOGL_ERROR, "unknown LAPD S cmd %x\n", data[2]); |
| 381 | return NULL; |
| 382 | }; |
| 383 | } else if ((data[2] & 3) == 3) { |
| 384 | typ = LAPD_TYPE_U; |
| 385 | pf = (data[2] >> 4) & 1; |
| 386 | int val = data[2] & ~(1 << 4); |
| 387 | switch (val) { |
| 388 | case 0x6f: |
| 389 | cmd = LAPD_CMD_SABME; |
| 390 | break; |
| 391 | case 0x0f: |
| 392 | cmd = LAPD_CMD_DM; |
| 393 | break; |
| 394 | case 0x03: |
| 395 | cmd = LAPD_CMD_UI; |
| 396 | break; |
| 397 | case 0x43: |
| 398 | cmd = LAPD_CMD_DISC; |
| 399 | break; |
| 400 | case 0x63: |
| 401 | cmd = LAPD_CMD_UA; |
| 402 | break; |
| 403 | case 0x87: |
| 404 | cmd = LAPD_CMD_FRMR; |
| 405 | break; |
| 406 | case 0xaf: |
| 407 | cmd = LAPD_CMD_XID; |
| 408 | break; |
| 409 | |
| 410 | default: |
| 411 | LOGP(DMI, LOGL_ERROR, "unknown U cmd %x " |
| 412 | "(pf %x data %x)\n", val, pf, data[2]); |
| 413 | return NULL; |
| 414 | }; |
| 415 | }; |
| 416 | |
| 417 | contents = &data[4]; |
| 418 | if (typ == LAPD_TYPE_U) |
| 419 | contents--; |
| 420 | *ilen = len - (contents - data); |
| 421 | |
| 422 | if (tei == 127) |
| 423 | lapd_tei_receive(li, contents, *ilen); |
| 424 | |
| 425 | teip = teip_from_tei(li, tei); |
| 426 | if (!teip) { |
| 427 | LOGP(DMI, LOGL_NOTICE, "Unknown TEI %u\n", tei); |
| 428 | return NULL; |
| 429 | } |
| 430 | |
| 431 | sap = lapd_sap_find(teip, sapi); |
| 432 | if (!sap) { |
| 433 | LOGP(DMI, LOGL_INFO, "No SAP for TEI=%u / SAPI=%u, " |
| 434 | "allocating\n", tei, sapi); |
| 435 | sap = lapd_sap_alloc(teip, sapi); |
| 436 | } |
| 437 | |
| 438 | DEBUGP(DMI, "<- %c %s sapi %x tei %3d cmd %x pf %x ns %3d nr %3d " |
| 439 | "ilen %d teip %p vs %d va %d vr %d len %d\n", |
| 440 | lapd_msg_types[typ], lapd_cmd_types[cmd], sapi, tei, command, pf, |
| 441 | ns, nr, *ilen, teip, sap->vs, sap->va, sap->vr, len); |
| 442 | |
| 443 | switch (cmd) { |
| 444 | case LAPD_CMD_I: |
| 445 | if (ns != sap->vr) { |
| 446 | DEBUGP(DMI, "ns %d != vr %d\n", ns, sap->vr); |
| 447 | if (ns == ((sap->vr - 1) & 0x7f)) { |
| 448 | DEBUGP(DMI, "DOUBLE FRAME, ignoring\n"); |
| 449 | cmd = 0; // ignore |
| 450 | } else { |
| 451 | assert(0); |
| 452 | }; |
| 453 | } else { |
| 454 | //printf("IN SEQUENCE\n"); |
| 455 | sap->vr = (ns + 1) & 0x7f; // FIXME: hack! |
| 456 | }; |
| 457 | |
| 458 | break; |
| 459 | case LAPD_CMD_UI: |
| 460 | break; |
| 461 | case LAPD_CMD_SABME: |
| 462 | sap->vs = 0; |
| 463 | sap->vr = 0; |
| 464 | sap->va = 0; |
| 465 | |
| 466 | // ua |
| 467 | resp[l++] = data[0]; |
| 468 | resp[l++] = (tei << 1) | 1; |
| 469 | resp[l++] = 0x73; |
| 470 | li->transmit_cb(resp, l, li->cbdata); |
| 471 | if (teip->state != LAPD_TEI_ACTIVE) { |
| 472 | if (teip->state == LAPD_TEI_ASSIGNED) { |
| 473 | lapd_tei_set_state(teip, |
| 474 | LAPD_TEI_ACTIVE); |
| 475 | //printf("ASSIGNED and ACTIVE\n"); |
| 476 | } else { |
| 477 | #if 0 |
| 478 | DEBUGP(DMI, "rr in strange state, send rej\n"); |
| 479 | |
| 480 | // rej |
| 481 | resp[l++] = (sap-> sapi << 2) | (li->network_side ? 0 : 2); |
| 482 | resp[l++] = (tei << 1) | 1; |
| 483 | resp[l++] = 0x09; //rej |
| 484 | resp[l++] = ((sap->vr + 1) << 1) | 0; |
| 485 | li->transmit_cb(resp, l, li->cbdata); |
| 486 | pf = 0; // dont reply |
| 487 | #endif |
| 488 | }; |
| 489 | }; |
| 490 | |
| 491 | *prim = LAPD_MPH_ACTIVATE_IND; |
| 492 | break; |
| 493 | case LAPD_CMD_UA: |
| 494 | sap->vs = 0; |
| 495 | sap->vr = 0; |
| 496 | sap->va = 0; |
| 497 | lapd_tei_set_state(teip, LAPD_TEI_ACTIVE); |
| 498 | lapd_sap_set_state(teip, sapi, SAP_STATE_ACTIVE); |
| 499 | *prim = LAPD_MPH_ACTIVATE_IND; |
| 500 | break; |
| 501 | case LAPD_CMD_RR: |
| 502 | sap->va = (nr & 0x7f); |
| 503 | #if 0 |
| 504 | if (teip->state != LAPD_TEI_ACTIVE) { |
| 505 | if (teip->state == LAPD_TEI_ASSIGNED) { |
| 506 | lapd_tei_set_state(teip, LAPD_TEI_ACTIVE); |
| 507 | *prim = LAPD_MPH_ACTIVATE_IND; |
| 508 | //printf("ASSIGNED and ACTIVE\n"); |
| 509 | } else { |
| 510 | #if 0 |
| 511 | DEBUGP(DMI, "rr in strange " "state, send rej\n"); |
| 512 | |
| 513 | // rej |
| 514 | resp[l++] = (sap-> sapi << 2) | (li->network_side ? 0 : 2); |
| 515 | resp[l++] = (tei << 1) | 1; |
| 516 | resp[l++] = 0x09; //rej |
| 517 | resp[l++] = |
| 518 | ((sap->vr + 1) << 1) | 0; |
| 519 | li->transmit_cb(resp, l, li->cbdata); |
| 520 | pf = 0; // dont reply |
| 521 | #endif |
| 522 | }; |
| 523 | }; |
| 524 | #endif |
| 525 | if (pf) { |
| 526 | // interrogating us, send rr |
| 527 | resp[l++] = data[0]; |
| 528 | resp[l++] = (tei << 1) | 1; |
| 529 | resp[l++] = 0x01; // rr |
| 530 | resp[l++] = (LAPD_NR(sap) << 1) | (data[3] & 1); // pf bit from req |
| 531 | |
| 532 | li->transmit_cb(resp, l, li->cbdata); |
| 533 | |
| 534 | }; |
| 535 | break; |
| 536 | case LAPD_CMD_FRMR: |
| 537 | // frame reject |
| 538 | #if 0 |
| 539 | if (teip->state == LAPD_TEI_ACTIVE) |
| 540 | *prim = LAPD_MPH_DEACTIVATE_IND; |
| 541 | lapd_tei_set_state(teip, LAPD_TEI_ASSIGNED); |
| 542 | #endif |
| 543 | LOGP(DMI, LOGL_NOTICE, "frame reject, ignoring\n"); |
| 544 | break; |
| 545 | case LAPD_CMD_DISC: |
| 546 | // disconnect |
| 547 | resp[l++] = data[0]; |
| 548 | resp[l++] = (tei << 1) | 1; |
| 549 | resp[l++] = 0x73; |
| 550 | li->transmit_cb(resp, l, li->cbdata); |
| 551 | lapd_tei_set_state(teip, LAPD_TEI_NONE); |
| 552 | break; |
| 553 | default: |
| 554 | LOGP(DMI, LOGL_NOTICE, "unknown cmd for tei %d (cmd %x)\n", |
| 555 | tei, cmd); |
| 556 | break; |
| 557 | } |
| 558 | |
| 559 | if (typ == LAPD_TYPE_I) { |
| 560 | /* send rr |
| 561 | * Thu Jan 22 19:17:13 2009 <4000> sangoma.c:340 read (62/25) 4: fa 33 01 0a |
| 562 | * lapd <- S RR sapi 3e tei 25 cmd 0 pf 0 ns -1 nr 5 ilen 0 teip 0x613800 vs 7 va 5 vr 2 len 4 |
| 563 | */ |
| 564 | |
| 565 | /* interrogating us, send rr */ |
| 566 | DEBUGP(DMI, "Sending RR response\n"); |
| 567 | resp[l++] = data[0]; |
| 568 | resp[l++] = (tei << 1) | 1; |
| 569 | resp[l++] = 0x01; // rr |
| 570 | resp[l++] = (LAPD_NR(sap) << 1) | (data[3] & 1); // pf bit from req |
| 571 | |
| 572 | li->transmit_cb(resp, l, li->cbdata); |
| 573 | |
| 574 | if (cmd != 0) { |
| 575 | *prim = LAPD_DL_DATA_IND; |
| 576 | return contents; |
| 577 | } |
| 578 | } else if (tei != 127 && typ == LAPD_TYPE_U && cmd == LAPD_CMD_UI) { |
| 579 | *prim = LAPD_DL_UNITDATA_IND; |
| 580 | return contents; |
| 581 | } |
| 582 | |
| 583 | return NULL; |
| 584 | }; |
| 585 | |
| 586 | /* low-level function to send a single SABM message */ |
| 587 | static int lapd_send_sabm(struct lapd_instance *li, uint8_t tei, uint8_t sapi) |
| 588 | { |
| 589 | struct msgb *msg = msgb_alloc_headroom(1024, 128, "LAPD SABM"); |
| 590 | if (!msg) |
| 591 | return -ENOMEM; |
| 592 | |
| 593 | DEBUGP(DMI, "Sending SABM for TEI=%u, SAPI=%u\n", tei, sapi); |
| 594 | |
| 595 | msgb_put_u8(msg, (sapi << 2) | (li->network_side ? 2 : 0)); |
| 596 | msgb_put_u8(msg, (tei << 1) | 1); |
| 597 | msgb_put_u8(msg, 0x7F); |
| 598 | |
| 599 | li->transmit_cb(msg->data, msg->len, li->cbdata); |
| 600 | |
| 601 | msgb_free(msg); |
| 602 | |
| 603 | return 0; |
| 604 | } |
| 605 | |
| 606 | /* timer call-back function for SABM re-transmission */ |
| 607 | static void sabme_timer_cb(void *_sap) |
| 608 | { |
| 609 | struct lapd_sap *sap = _sap; |
| 610 | |
| 611 | lapd_send_sabm(sap->tei->li, sap->tei->tei, sap->sapi); |
| 612 | |
| 613 | if (sap->state == SAP_STATE_SABM_RETRANS) |
| 614 | osmo_timer_schedule(&sap->sabme_timer, SABM_INTERVAL); |
| 615 | } |
| 616 | |
| 617 | /* Start a (user-side) SAP for the specified TEI/SAPI on the LAPD instance */ |
| 618 | int lapd_sap_start(struct lapd_instance *li, uint8_t tei, uint8_t sapi) |
| 619 | { |
| 620 | struct lapd_sap *sap; |
| 621 | struct lapd_tei *teip; |
| 622 | |
| 623 | teip = teip_from_tei(li, tei); |
| 624 | if (!teip) |
| 625 | teip = lapd_tei_alloc(li, tei); |
| 626 | |
| 627 | sap = lapd_sap_find(teip, sapi); |
| 628 | if (sap) |
| 629 | return -EEXIST; |
| 630 | |
| 631 | sap = lapd_sap_alloc(teip, sapi); |
| 632 | |
| 633 | lapd_sap_set_state(teip, sapi, SAP_STATE_SABM_RETRANS); |
| 634 | |
| 635 | return 0; |
| 636 | } |
| 637 | |
| 638 | /* Stop a (user-side) SAP for the specified TEI/SAPI on the LAPD instance */ |
| 639 | int lapd_sap_stop(struct lapd_instance *li, uint8_t tei, uint8_t sapi) |
| 640 | { |
| 641 | struct lapd_tei *teip; |
| 642 | struct lapd_sap *sap; |
| 643 | |
| 644 | teip = teip_from_tei(li, tei); |
| 645 | if (!teip) |
| 646 | return -ENODEV; |
| 647 | |
| 648 | sap = lapd_sap_find(teip, sapi); |
| 649 | if (!sap) |
| 650 | return -ENODEV; |
| 651 | |
| 652 | lapd_sap_set_state(teip, sapi, SAP_STATE_INACTIVE); |
| 653 | |
| 654 | llist_del(&sap->list); |
| 655 | talloc_free(sap); |
| 656 | |
| 657 | return 0; |
| 658 | } |
| 659 | |
| 660 | /* Transmit Data (I-Frame) on the given LAPD Instance / TEI / SAPI */ |
| 661 | void lapd_transmit(struct lapd_instance *li, uint8_t tei, uint8_t sapi, |
| 662 | uint8_t *data, unsigned int len) |
| 663 | { |
| 664 | struct lapd_tei *teip = teip_from_tei(li, tei); |
| 665 | struct lapd_sap *sap; |
| 666 | |
| 667 | if (!teip) { |
| 668 | LOGP(DMI, LOGL_ERROR, "Cannot transmit on non-existing " |
| 669 | "TEI %u\n", tei); |
| 670 | return; |
| 671 | } |
| 672 | |
| 673 | sap = lapd_sap_find(teip, sapi); |
| 674 | if (!sap) { |
| 675 | LOGP(DMI, LOGL_INFO, "Tx on unknown SAPI=%u in TEI=%u, " |
| 676 | "allocating\n", sapi, tei); |
| 677 | sap = lapd_sap_alloc(teip, sapi); |
| 678 | } |
| 679 | |
| 680 | /* prepend stuff */ |
| 681 | uint8_t buf[10000]; |
| 682 | memset(buf, 0, sizeof(buf)); |
| 683 | memmove(buf + 4, data, len); |
| 684 | len += 4; |
| 685 | |
| 686 | buf[0] = (sapi << 2) | (li->network_side ? 2 : 0); |
| 687 | buf[1] = (tei << 1) | 1; |
| 688 | buf[2] = (LAPD_NS(sap) << 1); |
| 689 | buf[3] = (LAPD_NR(sap) << 1) | 0; |
| 690 | |
| 691 | sap->vs = (sap->vs + 1) & 0x7f; |
| 692 | |
| 693 | li->transmit_cb(buf, len, li->cbdata); |
| 694 | }; |
| 695 | |
| 696 | /* Allocate a new LAPD instance */ |
| 697 | struct lapd_instance *lapd_instance_alloc(int network_side, |
| 698 | void (*tx_cb)(uint8_t *data, int len, |
| 699 | void *cbdata), void *cbdata) |
| 700 | { |
| 701 | struct lapd_instance *li; |
| 702 | |
| 703 | li = talloc_zero(NULL, struct lapd_instance); |
| 704 | if (!li) |
| 705 | return NULL; |
| 706 | |
| 707 | li->transmit_cb = tx_cb; |
| 708 | li->cbdata = cbdata; |
| 709 | li->network_side = network_side; |
| 710 | INIT_LLIST_HEAD(&li->tei_list); |
| 711 | |
| 712 | return li; |
| 713 | } |