First steps towards an open source implementation of the LE (Local Exchange) side of the ETSI/ITU V5 interface, in order to talk to Access Multiplexers (AN), such as Nokia EKSOS, DeTeWe ALIAN, etc.
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osmo-v5/lapv5.c

531 lines
15 KiB

/* LAPV5-DL as per Section 10.1 of ITU-T G.964 */
/* (C) 2021 by Harald Welte <laforge@gnumonks.org>
*
* All Rights Reserved
*
* SPDX-License-Identifier: GPL-2.0+
*
* 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 "v5x_internal.h"
#include "v5x_protocol.h"
#include "lapv5.h"
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <osmocom/core/linuxlist.h>
#include <osmocom/core/logging.h>
#include <osmocom/core/talloc.h>
#include <osmocom/core/msgb.h>
#include <osmocom/core/timer.h>
#include <osmocom/abis/lapd.h>
#include <osmocom/abis/lapd_pcap.h>
#define LAPD_ADDR2(sapi, cr) ((((sapi) & 0x3f) << 2) | (((cr) & 0x1) << 1))
#define LAPD_ADDR3(tei) ((((tei) & 0x7f) << 1) | 0x1)
#define LAPD_ADDR_SAPI(addr) ((addr) >> 2)
#define LAPD_ADDR_CR(addr) (((addr) >> 1) & 0x1)
#define LAPD_ADDR_EA(addr) ((addr) & 0x1)
#define LAPD_ADDR_TEI(addr) ((addr) >> 1)
#define LAPD_CTRL_I4(ns) (((ns) & 0x7f) << 1)
#define LAPD_CTRL_I5(nr, p) ((((nr) & 0x7f) << 1) | ((p) & 0x1))
#define LAPD_CTRL_S4(s) ((((s) & 0x3) << 2) | 0x1)
#define LAPD_CTRL_S5(nr, p) ((((nr) & 0x7f) << 1) | ((p) & 0x1))
#define LAPD_CTRL_U4(u, p) ((((u) & 0x1c) << (5-2)) | (((p) & 0x1) << 4) | (((u) & 0x3) << 2) | 0x3)
#define LAPD_CTRL_is_I(ctrl) (((ctrl) & 0x1) == 0)
#define LAPD_CTRL_is_S(ctrl) (((ctrl) & 0x3) == 1)
#define LAPD_CTRL_is_U(ctrl) (((ctrl) & 0x3) == 3)
#define LAPD_CTRL_U_BITS(ctrl) ((((ctrl) & 0xC) >> 2) | ((ctrl) & 0xE0) >> 3)
#define LAPD_CTRL_U_PF(ctrl) (((ctrl) >> 4) & 0x1)
#define LAPD_CTRL_S_BITS(ctrl) (((ctrl) & 0xC) >> 2)
#define LAPD_CTRL_S_PF(ctrl) (ctrl & 0x1)
#define LAPD_CTRL_I_Ns(ctrl) (((ctrl) & 0xFE) >> 1)
#define LAPD_CTRL_I_P(ctrl) (ctrl & 0x1)
#define LAPD_CTRL_Nr(ctrl) (((ctrl) & 0xFE) >> 1)
#define LAPD_LEN(len) ((len << 2) | 0x1)
#define LAPD_EL 0x1
#define LAPD_SET_K(n, o) {n,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}
#define LOGLI(li, level, fmt, args ...) \
LOGP(DLLAPD, level, "(%s): " fmt, (li)->name, ## args)
#define LOGSAP(sap, level, fmt, args ...) \
LOGP(DLLAPD, level, "(%s): " fmt, (sap)->dl.name, ## args)
#define DLSAP_MSGB_SIZE 128
#define DLSAP_MSGB_HEADROOM 56
const struct lapd_profile lapd_profile_lapv5dl = {
.k = LAPD_SET_K(7,7),
.n200 = 3,
.n201 = 260,
.n202 = 3,
.t200_sec = 1, .t200_usec = 0,
.t203_sec = 10, .t203_usec = 0,
.short_address = 0
};
/* Structure representing a SAP within a TEI. It includes exactly one datalink
* instance. */
struct lapv5_sap {
struct llist_head list; /* list of SAP within instance */
struct lapv5_instance *li; /* back-pointer */
uint16_t dladdr; /* V5-Data Link Address */
struct lapd_datalink dl; /* the actual data link */
};
/* Find a SAP within a given TEI */
static struct lapv5_sap *lapv5_sap_find(struct lapv5_instance *li, uint16_t dladdr)
{
struct lapv5_sap *sap;
llist_for_each_entry(sap, &li->sap_list, list) {
if (sap->dladdr == dladdr)
return sap;
}
return NULL;
}
static int send_ph_data_req(struct lapd_msg_ctx *lctx, struct msgb *msg);
static int send_dlsap(struct osmo_dlsap_prim *dp, struct lapd_msg_ctx *lctx);
/* Allocate a new SAP within a given instance */
static struct lapv5_sap *lapv5_sap_alloc(struct lapv5_instance *li, uint16_t v5dladdr)
{
struct lapv5_sap *sap;
struct lapd_datalink *dl;
struct lapd_profile *profile;
char name[256];
int k;
snprintf(name, sizeof(name), "%s-%u", li->name, v5dladdr);
sap = talloc_zero(li, struct lapv5_sap);
if (!sap)
return NULL;
LOGP(DLLAPD, LOGL_NOTICE, "(%s): LAPV5 Allocating SAP for V5_DLADDR=%u (dl=%p, sap=%p)\n",
name, v5dladdr, &sap->dl, sap);
sap->dladdr = v5dladdr;
dl = &sap->dl;
profile = &li->profile;
k = profile->k[0];
LOGP(DLLAPD, LOGL_NOTICE, "(%s): k=%d N200=%d N201=%d T200=%d.%d T203=%d.%d\n",
name, k, profile->n200, profile->n201, profile->t200_sec,
profile->t200_usec, profile->t203_sec, profile->t203_usec);
lapd_dl_init2(dl, k, 128, profile->n201, name);
dl->use_sabme = 1; /* use SABME instead of SABM (GSM) */
dl->send_ph_data_req = send_ph_data_req;
dl->send_dlsap = send_dlsap;
dl->n200 = profile->n200;
dl->n200_est_rel = profile->n200;
dl->t200_sec = profile->t200_sec; dl->t200_usec = profile->t200_usec;
dl->t203_sec = profile->t203_sec; dl->t203_usec = profile->t203_usec;
dl->lctx.dl = &sap->dl;
dl->lctx.sapi = v5dladdr & 0xff;
dl->lctx.tei = v5dladdr >> 8;
dl->lctx.n201 = profile->n201;
lapd_set_mode(&sap->dl, (li->network_side) ? LAPD_MODE_NETWORK : LAPD_MODE_USER);
llist_add(&sap->list, &li->sap_list);
return sap;
}
/* Free SAP instance, including the datalink */
static void lapv5_sap_free(struct lapv5_sap *sap)
{
LOGSAP(sap, LOGL_NOTICE, "LAPV5 Freeing SAP for DLADDR=%u (dl=%p, sap=%p)\n", sap->dladdr, &sap->dl, sap);
/* free datalink structures and timers */
lapd_dl_exit(&sap->dl);
llist_del(&sap->list);
talloc_free(sap);
}
/* General input function for any data received for this LAPV5 instance */
int lapv5_receive(struct lapv5_instance *li, struct msgb *msg, int *error)
{
struct lapd_msg_ctx lctx;
struct lapv5_sap *sap;
uint16_t dladdr;
bool is_isdn;
int i;
/* write to PCAP file, if enabled. */
osmo_pcap_lapd_write(li->pcap_fd, OSMO_LAPD_PCAP_INPUT, msg);
LOGLI(li, LOGL_DEBUG, "RX: %s\n", osmo_hexdump(msg->data, msg->len));
if (msg->len < 2) {
LOGLI(li, LOGL_ERROR, "LAPV5 frame receive len %d < 2, ignoring\n", msg->len);
*error = LAPD_ERR_BAD_LEN;
return -EINVAL;
};
msg->l2h = msg->data;
memset(&lctx, 0, sizeof(lctx));
i = 0;
/* adress field */
dladdr = v51_l3_addr_dec(msg->l2h[0] << 8 | msg->l2h[1], &is_isdn);
if (!is_isdn) {
LOGLI(li, LOGL_ERROR, "LAPV5 frame with single-octet addr not permitted\n");
*error = LAPD_ERR_BAD_LEN;
return -EINVAL;
};
lctx.lpd = 0;
lctx.tei = dladdr >> 8;
lctx.sapi = dladdr & 0xff;
lctx.cr = LAPD_ADDR_CR(msg->l2h[0]);
i += 2;
/* control field */
if (LAPD_CTRL_is_I(msg->l2h[i])) {
lctx.format = LAPD_FORM_I;
lctx.n_send = LAPD_CTRL_I_Ns(msg->l2h[i]);
i++;
if (msg->len < 4) {
LOGLI(li, LOGL_ERROR, "LAPV5 I frame receive len %d < 4, ignoring\n", msg->len);
*error = LAPD_ERR_BAD_LEN;
return -EINVAL;
}
lctx.n_recv = LAPD_CTRL_Nr(msg->l2h[i]);
lctx.p_f = LAPD_CTRL_I_P(msg->l2h[i]);
} else if (LAPD_CTRL_is_S(msg->l2h[i])) {
lctx.format = LAPD_FORM_S;
lctx.s_u = LAPD_CTRL_S_BITS(msg->l2h[i]);
i++;
if (msg->len < 4 && i == 3) {
LOGLI(li, LOGL_ERROR, "LAPV5 S frame receive len %d < 4, ignoring\n", msg->len);
*error = LAPD_ERR_BAD_LEN;
return -EINVAL;
}
lctx.n_recv = LAPD_CTRL_Nr(msg->l2h[i]);
lctx.p_f = LAPD_CTRL_S_PF(msg->l2h[i]);
} else if (LAPD_CTRL_is_U(msg->l2h[i])) {
lctx.format = LAPD_FORM_U;
lctx.s_u = LAPD_CTRL_U_BITS(msg->l2h[i]);
lctx.p_f = LAPD_CTRL_U_PF(msg->l2h[i]);
} else
lctx.format = LAPD_FORM_UKN;
i++;
/* length */
msg->l3h = msg->l2h + i;
msgb_pull(msg, i);
lctx.length = msg->len;
sap = lapv5_sap_find(li, dladdr);
if (!sap) {
LOGLI(li, LOGL_INFO, "LAPV5 No SAP for DLADDR=%u, allocating\n", dladdr);
sap = lapv5_sap_alloc(li, dladdr);
if (!sap) {
*error = LAPD_ERR_NO_MEM;
msgb_free(msg);
return -ENOMEM;
}
}
lctx.dl = &sap->dl;
lctx.n201 = lctx.dl->maxf;
if (msg->len > lctx.n201) {
LOGSAP(sap, LOGL_ERROR, "message len %d > N201(%d) (discarding)\n", msg->len, lctx.n201);
msgb_free(msg);
*error = LAPD_ERR_BAD_LEN;
return -EINVAL;
}
/* send to LAPD */
return lapd_ph_data_ind(msg, &lctx);
}
/* Start a (user-side) SAP for the specified TEI/SAPI on the LAPD instance */
int lapv5_sap_start(struct lapv5_instance *li, uint16_t dladdr)
{
struct lapv5_sap *sap;
struct osmo_dlsap_prim dp;
struct msgb *msg;
sap = lapv5_sap_find(li, dladdr);
if (sap)
return -EEXIST;
sap = lapv5_sap_alloc(li, dladdr);
if (!sap)
return -ENOMEM;
LOGSAP(sap, LOGL_NOTICE, "LAPV5 DL-ESTABLISH request DLADDR=%u\n", dladdr);
/* prepare prim */
msg = msgb_alloc_headroom(DLSAP_MSGB_SIZE, DLSAP_MSGB_HEADROOM, "DL EST");
msg->l3h = msg->data;
osmo_prim_init(&dp.oph, 0, PRIM_DL_EST, PRIM_OP_REQUEST, msg);
/* send to L2 */
return lapd_recv_dlsap(&dp, &sap->dl.lctx);
}
/* Stop a (user-side) SAP for the specified TEI/SAPI on the LAPD instance */
int lapv5_sap_stop(struct lapv5_instance *li, uint16_t dladdr)
{
struct lapv5_sap *sap;
struct osmo_dlsap_prim dp;
struct msgb *msg;
sap = lapv5_sap_find(li, dladdr);
if (!sap)
return -ENODEV;
LOGSAP(sap, LOGL_NOTICE, "LAPV5 DL-RELEASE request DLADDR=%u\n", dladdr);
/* prepare prim */
msg = msgb_alloc_headroom(DLSAP_MSGB_SIZE, DLSAP_MSGB_HEADROOM, "DL REL");
msg->l3h = msg->data;
osmo_prim_init(&dp.oph, 0, PRIM_DL_REL, PRIM_OP_REQUEST, msg);
/* send to L2 */
return lapd_recv_dlsap(&dp, &sap->dl.lctx);
}
/* Transmit Data (DL-DATA request) on the given LAPD Instance / DLADDR */
void lapv5_transmit(struct lapv5_instance *li, uint8_t dladdr, struct msgb *msg)
{
struct lapv5_sap *sap;
struct osmo_dlsap_prim dp;
sap = lapv5_sap_find(li, dladdr);
if (!sap) {
LOGLI(li, LOGL_INFO, "LAPV5 Tx on unknown DLADDR=%u\n", dladdr);
msgb_free(msg);
return;
}
/* prepare prim */
msg->l3h = msg->data;
osmo_prim_init(&dp.oph, 0, PRIM_DL_DATA, PRIM_OP_REQUEST, msg);
/* send to L2 */
lapd_recv_dlsap(&dp, &sap->dl.lctx);
};
static int send_ph_data_req(struct lapd_msg_ctx *lctx, struct msgb *msg)
{
struct lapd_datalink *dl = lctx->dl;
struct lapv5_sap *sap = container_of(dl, struct lapv5_sap, dl);
struct lapv5_instance *li = sap->li;
int format = lctx->format;
/* control field */
switch (format) {
case LAPD_FORM_I:
msg->l2h = msgb_push(msg, 2);
msg->l2h[0] = LAPD_CTRL_I4(lctx->n_send);
msg->l2h[1] = LAPD_CTRL_I5(lctx->n_recv, lctx->p_f);
break;
case LAPD_FORM_S:
msg->l2h = msgb_push(msg, 2);
msg->l2h[0] = LAPD_CTRL_S4(lctx->s_u);
msg->l2h[1] = LAPD_CTRL_S5(lctx->n_recv, lctx->p_f);
break;
case LAPD_FORM_U:
msg->l2h = msgb_push(msg, 1);
msg->l2h[0] = LAPD_CTRL_U4(lctx->s_u, lctx->p_f);
break;
default:
msgb_free(msg);
return -EINVAL;
}
/* address field */
msg->l2h = msgb_push(msg, 2);
msg->l2h[0] = LAPD_ADDR2(lctx->sapi, lctx->cr);
msg->l2h[1] = LAPD_ADDR3(lctx->tei);
/* write to PCAP file, if enabled. */
osmo_pcap_lapd_write(li->pcap_fd, OSMO_LAPD_PCAP_OUTPUT, msg);
/* forward frame to L1 */
LOGDL(dl, LOGL_DEBUG, "TX: %s\n", osmo_hexdump(msg->data, msg->len));
li->transmit_cb(msg, li->transmit_cbdata);
return 0;
}
/* A DL-SAP message is received from datalink instance and forwarded to L3 */
static int send_dlsap(struct osmo_dlsap_prim *dp, struct lapd_msg_ctx *lctx)
{
struct lapd_datalink *dl = lctx->dl;
struct lapv5_sap *sap = container_of(dl, struct lapv5_sap, dl);
struct lapv5_instance *li;
const char *op = (dp->oph.operation == PRIM_OP_INDICATION) ? "indication" : "confirm";
uint16_t dladdr;
li = sap->li;
dladdr = lctx->tei << 8 | lctx->sapi;
switch (dp->oph.primitive) {
case PRIM_DL_EST:
LOGDL(dl, LOGL_NOTICE, "LAPD DL-ESTABLISH %s DLADDR=%u\n", op, dladdr);
break;
case PRIM_DL_REL:
LOGDL(dl, LOGL_NOTICE, "LAPD DL-RELEASE %s DLADDR=%u\n", op, dladdr);
lapv5_sap_free(sap);
/* note: sap and dl is now gone, don't use it anymore */
break;
default:
;
}
li->receive_cb(dp, dladdr, li->receive_cbdata);
return 0;
}
/* Allocate a new LAPV5 instance */
struct lapv5_instance *lapv5_instance_alloc(int network_side,
void (*tx_cb)(struct msgb *msg, void *cbdata), void *tx_cbdata,
void (*rx_cb)(struct osmo_dlsap_prim *odp, uint16_t dladdr, void *rx_cbdata), void *rx_cbdata,
const struct lapd_profile *profile, const char *name)
{
struct lapv5_instance *li;
li = talloc_zero(NULL, struct lapv5_instance);
if (!li)
return NULL;
li->network_side = network_side;
li->transmit_cb = tx_cb;
li->transmit_cbdata = tx_cbdata;
li->receive_cb = rx_cb;
li->receive_cbdata = rx_cbdata;
li->pcap_fd = -1;
li->name = talloc_strdup(li, name);
memcpy(&li->profile, profile, sizeof(li->profile));
INIT_LLIST_HEAD(&li->sap_list);
return li;
}
/* Change lapd-profile on the fly (use with caution!) */
void lapv5_instance_set_profile(struct lapv5_instance *li, const struct lapd_profile *profile)
{
memcpy(&li->profile, profile, sizeof(li->profile));
}
void lapv5_instance_free(struct lapv5_instance *li)
{
struct lapv5_sap *sap, *sap2;
/* Free all SAP instances */
llist_for_each_entry_safe(sap, sap2, &li->sap_list, list) {
lapv5_sap_free(sap);
}
talloc_free(li);
}
/***********************************************************************
* LAPV5-EF (Encapsulation Function)
***********************************************************************/
/* The LAPV5-EF adds another layer around of the LAPD-style LAPV5-DL. It consists of
* a two-byte header in front of the normal data link header. Examples see Figure E.1/G.964 */
/* main entry point for receiving signaling frames from the AN. The assumption is that
* the flag octets are removed and the msg->data points to the first octet of the EFaddr,
* while the last octet (before msg->tail) points to the last FCS octet. */
int lapv5ef_rx(struct v5x_link *link, struct msgb *msg)
{
struct lapd_datalink *dl;
uint16_t efaddr, efaddr_enc;
bool is_isdn;
msg->l1h = msg->data;
if (msgb_length(msg) < 2) {
msgb_free(msg);
return -EINVAL;
}
msg->l2h = msg->l1h + 2;
efaddr_enc = msg->l1h[0] << 8 | msg->l1h[1];
efaddr = v51_l3_addr_dec(efaddr_enc, &is_isdn);
if (!is_isdn) {
/* EFaddr are structured like isdn-type L3 Address */
msgb_free(msg);
return -EINVAL;
}
switch (efaddr) {
case V51_DLADDR_PSTN:
/* hand-over to LAPD-DL instance for PSTN */
dl = &link->interface->pstn.dl;
/* TODO */
break;
case V51_DLADDR_CTRL:
/* hand-over to LAPD-DL instance for CTRL */
/* TODO */
dl = &link->interface->control.dl;
break;
case V52_DLADDR_BCC:
dl = &link->interface->bcc.dl;
/* TOOD: implement V5.2 */
msgb_free(msg);
break;
case V52_DLADDR_PROTECTION:
dl = &link->interface->protection[0].dl;
/* TOOD: implement V5.2 */
msgb_free(msg);
break;
case V52_DLADDR_LCP:
dl = &link->interface->lcp.dl;
/* TOOD: implement V5.2 */
msgb_free(msg);
break;
default:
if (efaddr >= 8176) {
/* reserved as per Section 9.2.2.2 of G.964 */
msgb_free(msg);
return -EINVAL;
}
/* relay function for LAPD of user ports */
/* TODO */
}
return 0;
}