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libpri/q921.c

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/*
* libpri: An implementation of Primary Rate ISDN
*
* Written by Mark Spencer <markster@digium.com>
*
* Copyright (C) 2001-2005, Digium, Inc.
* All Rights Reserved.
*/
/*
* See http://www.asterisk.org for more information about
* the Asterisk project. Please do not directly contact
* any of the maintainers of this project for assistance;
* the project provides a web site, mailing lists and IRC
* channels for your use.
*
* This program is free software, distributed under the terms of
* the GNU General Public License Version 2 as published by the
* Free Software Foundation. See the LICENSE file included with
* this program for more details.
*
* In addition, when this program is distributed with Asterisk in
* any form that would qualify as a 'combined work' or as a
* 'derivative work' (but not mere aggregation), you can redistribute
* and/or modify the combination under the terms of the license
* provided with that copy of Asterisk, instead of the license
* terms granted here.
*/
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include "compat.h"
#include "libpri.h"
#include "pri_internal.h"
#include "pri_q921.h"
#include "pri_q931.h"
/*
* Define RANDOM_DROPS To randomly drop packets in order to simulate loss for testing
* retransmission functionality
*/
/*
#define RANDOM_DROPS
*/
#define Q921_INIT(pri, hf) do { \
memset(&(hf),0,sizeof(hf)); \
(hf).h.sapi = (pri)->sapi; \
(hf).h.ea1 = 0; \
(hf).h.ea2 = 1; \
(hf).h.tei = (pri)->tei; \
} while(0)
static void reschedule_t203(struct pri *pri);
static void reschedule_t200(struct pri *pri);
static void q921_restart(struct pri *pri, int now);
static void q921_tei_release_and_reacquire(struct pri *master);
static void q921_discard_retransmissions(struct pri *pri)
{
struct q921_frame *f, *p;
f = pri->txqueue;
while(f) {
p = f;
f = f->next;
/* Free frame */
free(p);
}
pri->txqueue = NULL;
}
static int q921_transmit(struct pri *pri, q921_h *h, int len)
{
int res;
if (pri->master)
pri = pri->master;
#ifdef RANDOM_DROPS
if (!(random() % 3)) {
pri_message(pri, " === Dropping Packet ===\n");
return 0;
}
#endif
#ifdef LIBPRI_COUNTERS
pri->q921_txcount++;
#endif
/* Just send it raw */
if (pri->debug & (PRI_DEBUG_Q921_DUMP | PRI_DEBUG_Q921_RAW))
q921_dump(pri, h, len, pri->debug & PRI_DEBUG_Q921_RAW, 1);
/* Write an extra two bytes for the FCS */
res = pri->write_func ? pri->write_func(pri, h, len + 2) : 0;
if (res != (len + 2)) {
pri_error(pri, "Short write: %d/%d (%s)\n", res, len + 2, strerror(errno));
return -1;
}
return 0;
}
static void q921_send_tei(struct pri *pri, int message, int ri, int ai, int iscommand)
{
q921_u *f;
if (!(f = calloc(1, sizeof(*f) + 5)))
return;
Q921_INIT(pri, *f);
f->h.c_r = (pri->localtype == PRI_NETWORK) ? iscommand : !iscommand;
f->ft = Q921_FRAMETYPE_U;
f->data[0] = 0x0f; /* Management entity */
f->data[1] = (ri >> 8) & 0xff;
f->data[2] = ri & 0xff;
f->data[3] = message;
f->data[4] = (ai << 1) | 1;
if (pri->debug & PRI_DEBUG_Q921_STATE)
pri_message(pri, "Sending TEI management message %d, TEI=%d\n", message, ai);
q921_transmit(pri, (q921_h *)f, 8);
free(f);
}
static void q921_tei_request(void *vpri)
{
struct pri *pri = (struct pri *)vpri;
if (pri->subchannel) {
pri_error(pri, "Cannot request TEI while its already assigned\n");
return;
}
pri->n202_counter++;
#if 0
if (pri->n202_counter > pri->timers[PRI_TIMER_N202]) {
pri_error(pri, "Unable to assign TEI from network\n");
return;
}
#endif
pri->ri = random() % 65535;
q921_send_tei(pri, Q921_TEI_IDENTITY_REQUEST, pri->ri, Q921_TEI_GROUP, 1);
pri_schedule_del(pri, pri->t202_timer);
pri->t202_timer = pri_schedule_event(pri, pri->timers[PRI_TIMER_T202], q921_tei_request, pri);
}
static void q921_send_ua(struct pri *pri, int pfbit)
{
q921_h h;
Q921_INIT(pri, h);
h.u.m3 = 3; /* M3 = 3 */
h.u.m2 = 0; /* M2 = 0 */
h.u.p_f = pfbit; /* Final bit on */
h.u.ft = Q921_FRAMETYPE_U;
switch(pri->localtype) {
case PRI_NETWORK:
h.h.c_r = 0;
break;
case PRI_CPE:
h.h.c_r = 1;
break;
default:
pri_error(pri, "Don't know how to U/A on a type %d node\n", pri->localtype);
return;
}
if (pri->debug & (PRI_DEBUG_Q921_STATE | PRI_DEBUG_Q921_DUMP))
pri_message(pri, "Sending Unnumbered Acknowledgement\n");
q921_transmit(pri, &h, 3);
}
static void q921_send_sabme_now(void *vpri);
static void q921_send_sabme(void *vpri, int now)
{
struct pri *pri = vpri;
q921_h h;
pri_schedule_del(pri, pri->sabme_timer);
pri->sabme_timer = pri_schedule_event(pri, pri->timers[PRI_TIMER_T200], q921_send_sabme_now, pri);
if (!now)
return;
Q921_INIT(pri, h);
h.u.m3 = 3; /* M3 = 3 */
h.u.m2 = 3; /* M2 = 3 */
h.u.p_f = 1; /* Poll bit set */
h.u.ft = Q921_FRAMETYPE_U;
switch(pri->localtype) {
case PRI_NETWORK:
h.h.c_r = 1;
break;
case PRI_CPE:
h.h.c_r = 0;
break;
default:
pri_error(pri, "Don't know how to U/A on a type %d node\n", pri->localtype);
return;
}
if (pri->bri && (pri->state == Q921_AWAITING_ESTABLISH)) {
if (pri->sabme_count >= pri->timers[PRI_TIMER_N200]) {
pri_schedule_del(pri, pri->sabme_timer);
pri->sabme_timer = 0;
q921_tei_release_and_reacquire(pri->master);
} else {
pri->sabme_count++;
}
}
if (pri->debug & (PRI_DEBUG_Q921_STATE | PRI_DEBUG_Q921_DUMP))
pri_message(pri, "Sending Set Asynchronous Balanced Mode Extended\n");
q921_transmit(pri, &h, 3);
if (pri->debug & PRI_DEBUG_Q921_STATE && pri->q921_state != Q921_AWAITING_ESTABLISH)
pri_message(pri, DBGHEAD "q921_state now is Q921_AWAITING_ESTABLISH\n", DBGINFO);
pri->q921_state = Q921_AWAITING_ESTABLISH;
}
static void q921_send_sabme_now(void *vpri)
{
q921_send_sabme(vpri, 1);
}
static int q921_ack_packet(struct pri *pri, int num)
{
struct q921_frame *f, *prev = NULL;
f = pri->txqueue;
while(f) {
if (f->h.n_s == num) {
/* Cancel each packet as necessary */
/* That's our packet */
if (prev)
prev->next = f->next;
else
pri->txqueue = f->next;
if (pri->debug & PRI_DEBUG_Q921_DUMP)
pri_message(pri, "-- ACKing packet %d, new txqueue is %d (-1 means empty)\n", f->h.n_s, pri->txqueue ? pri->txqueue->h.n_s : -1);
/* Update v_a */
pri->v_a = num;
free(f);
/* Reset retransmission counter if we actually acked something */
pri->retrans = 0;
/* Decrement window size */
pri->windowlen--;
return 1;
}
prev = f;
f = f->next;
}
return 0;
}
static void t203_expire(void *);
static void t200_expire(void *);
static void reschedule_t200(struct pri *pri)
{
if (pri->debug & PRI_DEBUG_Q921_DUMP)
pri_message(pri, "-- Restarting T200 timer\n");
pri_schedule_del(pri, pri->t200_timer);
pri->t200_timer = pri_schedule_event(pri, pri->timers[PRI_TIMER_T200], t200_expire, pri);
}
static void reschedule_t203(struct pri *pri)
{
if (pri->debug & PRI_DEBUG_Q921_DUMP)
pri_message(pri, "-- Restarting T203 timer\n");
pri_schedule_del(pri, pri->t203_timer);
pri->t203_timer = pri_schedule_event(pri, pri->timers[PRI_TIMER_T203], t203_expire, pri);
}
static void q921_send_queued_iframes(struct pri *pri)
{
struct q921_frame *f;
f = pri->txqueue;
while(f && (pri->windowlen < pri->window)) {
if (!f->transmitted) {
/* Send it now... */
if (pri->debug & PRI_DEBUG_Q921_DUMP)
pri_message(pri, "-- Finally transmitting %d, since window opened up (%d)\n", f->h.n_s, pri->windowlen);
f->transmitted++;
pri->windowlen++;
f->h.n_r = pri->v_r;
f->h.p_f = 0;
q921_transmit(pri, (q921_h *)(&f->h), f->len);
}
f = f->next;
}
}
static pri_event *q921_ack_rx(struct pri *pri, int ack, int send_untransmitted_frames)
{
int x;
int cnt=0;
pri_event *ev;
/* Make sure the ACK was within our window */
for (x=pri->v_a; (x != pri->v_s) && (x != ack); Q921_INC(x));
if (x != ack) {
/* ACK was outside of our window --- ignore */
pri_error(pri, "ACK received for '%d' outside of window of '%d' to '%d', restarting\n", ack, pri->v_a, pri->v_s);
ev = q921_dchannel_down(pri);
q921_start(pri, 1);
pri->schedev = 1;
return ev;
}
/* Cancel each packet as necessary */
if (pri->debug & PRI_DEBUG_Q921_DUMP)
pri_message(pri, "-- ACKing all packets from %d to (but not including) %d\n", pri->v_a, ack);
for (x=pri->v_a; x != ack; Q921_INC(x))
cnt += q921_ack_packet(pri, x);
if (!pri->txqueue) {
if (pri->debug & PRI_DEBUG_Q921_DUMP)
pri_message(pri, "-- Since there was nothing left, stopping T200 counter\n");
/* Something was ACK'd. Stop T200 counter */
pri_schedule_del(pri, pri->t200_timer);
pri->t200_timer = 0;
}
if (pri->t203_timer) {
if (pri->debug & PRI_DEBUG_Q921_DUMP)
pri_message(pri, "-- Stopping T203 counter since we got an ACK\n");
pri_schedule_del(pri, pri->t203_timer);
pri->t203_timer = 0;
}
if (pri->txqueue) {
/* Something left to transmit, Start the T200 counter again if we stopped it */
if (!pri->busy && send_untransmitted_frames) {
pri->retrans = 0;
/* Search for something to send */
q921_send_queued_iframes(pri);
}
if (pri->debug & PRI_DEBUG_Q921_DUMP)
pri_message(pri, "-- Waiting for acknowledge, restarting T200 counter\n");
reschedule_t200(pri);
} else {
if (pri->debug & PRI_DEBUG_Q921_DUMP)
pri_message(pri, "-- Nothing left, starting T203 counter\n");
/* Nothing to transmit, start the T203 counter instead */
pri->t203_timer = pri_schedule_event(pri, pri->timers[PRI_TIMER_T203], t203_expire, pri);
}
return NULL;
}
static void q921_reject(struct pri *pri, int pf)
{
q921_h h;
Q921_INIT(pri, h);
h.s.x0 = 0; /* Always 0 */
h.s.ss = 2; /* Reject */
h.s.ft = 1; /* Frametype (01) */
h.s.n_r = pri->v_r; /* Where to start retransmission */
h.s.p_f = pf;
switch(pri->localtype) {
case PRI_NETWORK:
h.h.c_r = 0;
break;
case PRI_CPE:
h.h.c_r = 1;
break;
default:
pri_error(pri, "Don't know how to U/A on a type %d node\n", pri->localtype);
return;
}
if (pri->debug & PRI_DEBUG_Q921_DUMP)
pri_message(pri, "Sending Reject (%d)\n", pri->v_r);
pri->sentrej = 1;
q921_transmit(pri, &h, 4);
}
static void q921_rr(struct pri *pri, int pbit, int cmd) {
q921_h h;
Q921_INIT(pri, h);
h.s.x0 = 0; /* Always 0 */
h.s.ss = 0; /* Receive Ready */
h.s.ft = 1; /* Frametype (01) */
h.s.n_r = pri->v_r; /* N/R */
h.s.p_f = pbit; /* Poll/Final set appropriately */
switch(pri->localtype) {
case PRI_NETWORK:
if (cmd)
h.h.c_r = 1;
else
h.h.c_r = 0;
break;
case PRI_CPE:
if (cmd)
h.h.c_r = 0;
else
h.h.c_r = 1;
break;
default:
pri_error(pri, "Don't know how to U/A on a type %d node\n", pri->localtype);
return;
}
pri->v_na = pri->v_r; /* Make a note that we've already acked this */
if (pri->debug & PRI_DEBUG_Q921_DUMP)
pri_message(pri, "Sending Receiver Ready (%d)\n", pri->v_r);
q921_transmit(pri, &h, 4);
}
static void t200_expire(void *vpri)
{
struct pri *pri = vpri;
q921_frame *f, *lastframe=NULL;
if (pri->txqueue) {
/* Retransmit first packet in the queue, setting the poll bit */
if (pri->debug & PRI_DEBUG_Q921_DUMP)
pri_message(pri, "-- T200 counter expired, What to do...\n");
pri->solicitfbit = 1;
/* Up to three retransmissions */
if (pri->retrans < pri->timers[PRI_TIMER_N200]) {
pri->retrans++;
/* Reschedule t200_timer */
if (pri->debug & PRI_DEBUG_Q921_DUMP)
pri_message(pri, "-- Retransmitting %d bytes\n", pri->txqueue->len);
if (pri->busy)
q921_rr(pri, 1, 1);
else {
if (!pri->txqueue->transmitted)
pri_error(pri, "!! Not good - head of queue has not been transmitted yet\n");
/*Actually we need to retransmit the last transmitted packet, setting the poll bit */
for (f=pri->txqueue; f; f = f->next) {
if (f->transmitted)
lastframe = f;
}
if (lastframe) {
/* Force Poll bit */
lastframe->h.p_f = 1;
/* Update nr */
lastframe->h.n_r = pri->v_r;
pri->v_na = pri->v_r;
q921_transmit(pri, (q921_h *)&lastframe->h, lastframe->len);
}
}
if (pri->debug & PRI_DEBUG_Q921_DUMP)
pri_message(pri, "-- Rescheduling retransmission (%d)\n", pri->retrans);
pri->t200_timer = pri_schedule_event(pri, pri->timers[PRI_TIMER_T200], t200_expire, pri);
} else {
if (pri->debug & PRI_DEBUG_Q921_STATE)
pri_message(pri, "-- Timeout occured, restarting PRI\n");
if (pri->debug & PRI_DEBUG_Q921_STATE && pri->q921_state != Q921_LINK_CONNECTION_RELEASED)
pri_message(pri, DBGHEAD "q921_state now is Q921_LINK_CONNECTION_RELEASED\n",DBGINFO);
pri->q921_state = Q921_LINK_CONNECTION_RELEASED;
pri->t200_timer = 0;
if (pri->bri && pri->master) {
q921_tei_release_and_reacquire(pri->master);
return;
} else {
q921_dchannel_down(pri);
q921_start(pri, 1);
pri->schedev = 1;
}
}
} else if (pri->solicitfbit) {
if (pri->debug & PRI_DEBUG_Q921_DUMP)
pri_message(pri, "-- Retrying poll with f-bit\n");
if (pri->retrans < pri->timers[PRI_TIMER_N200]) {
pri->retrans++;
pri->solicitfbit = 1;
q921_rr(pri, 1, 1);
pri->t200_timer = pri_schedule_event(pri, pri->timers[PRI_TIMER_T200], t200_expire, pri);
} else {
if (pri->debug & PRI_DEBUG_Q921_STATE)
pri_message(pri, "-- Timeout occured, restarting PRI\n");
if (pri->debug & PRI_DEBUG_Q921_STATE && pri->q921_state != Q921_LINK_CONNECTION_RELEASED)
pri_message(pri, DBGHEAD "q921_state now is Q921_LINK_CONNECTION_RELEASED\n", DBGINFO);
pri->q921_state = Q921_LINK_CONNECTION_RELEASED;
pri->t200_timer = 0;
if (pri->bri && pri->master) {
q921_tei_release_and_reacquire(pri->master);
return;
} else {
q921_dchannel_down(pri);
q921_start(pri, 1);
pri->schedev = 1;
}
}
} else {
pri_error(pri, "T200 counter expired, nothing to send...\n");
pri->t200_timer = 0;
}
}
int q921_transmit_uiframe(struct pri *pri, void *buf, int len)
{
uint8_t ubuf[512];
q921_h *h = (void *)&ubuf[0];
if (len >= 512) {
pri_error(pri, "Requested to send UI frame larger than 512 bytes!\n");
return -1;
}
memset(ubuf, 0, sizeof(ubuf));
h->h.sapi = 0;
h->h.ea1 = 0;
h->h.ea2 = 1;
h->h.tei = pri->tei;
h->u.m3 = 0;
h->u.m2 = 0;
h->u.p_f = 0; /* Poll bit set */
h->u.ft = Q921_FRAMETYPE_U;
switch(pri->localtype) {
case PRI_NETWORK:
h->h.c_r = 1;
break;
case PRI_CPE:
h->h.c_r = 0;
break;
default:
pri_error(pri, "Don't know how to U/A on a type %d node\n", pri->localtype);
return -1;
}
memcpy(h->u.data, buf, len);
q921_transmit(pri, h, len + 3);
return 0;
}
int q921_transmit_iframe(struct pri *pri, void *buf, int len, int cr)
{
q921_frame *f, *prev=NULL;
for (f=pri->txqueue; f; f = f->next) prev = f;
f = calloc(1, sizeof(q921_frame) + len + 2);
if (f) {
Q921_INIT(pri, f->h);
switch(pri->localtype) {
case PRI_NETWORK:
if (cr)
f->h.h.c_r = 1;
else
f->h.h.c_r = 0;
break;
case PRI_CPE:
if (cr)
f->h.h.c_r = 0;
else
f->h.h.c_r = 1;
break;
}
f->next = NULL;
f->transmitted = 0;
f->len = len + 4;
memcpy(f->h.data, buf, len);
f->h.n_s = pri->v_s;
f->h.n_r = pri->v_r;
pri->v_s++;
pri->v_na = pri->v_r;
f->h.p_f = 0;
f->h.ft = 0;
if (prev)
prev->next = f;
else
pri->txqueue = f;
/* Immediately transmit unless we're in a recovery state, or the window
size is too big */
if (pri->debug & PRI_DEBUG_Q921_DUMP) {
pri_message(pri, "TEI/SAPI: %d/%d state %d retran %d busy %d\n",
pri->tei, pri->sapi, pri->q921_state, pri->retrans, pri->busy);
}
if ((pri->q921_state == Q921_LINK_CONNECTION_ESTABLISHED) && (!pri->retrans && !pri->busy)) {
if (pri->windowlen < pri->window) {
q921_send_queued_iframes(pri);
} else {
if (pri->debug & PRI_DEBUG_Q921_DUMP)
pri_message(pri, "Delaying transmission of %d, window is %d/%d long\n",
f->h.n_s, pri->windowlen, pri->window);
}
}
if (pri->t203_timer) {
if (pri->debug & PRI_DEBUG_Q921_DUMP)
pri_message(pri, "Stopping T_203 timer\n");
pri_schedule_del(pri, pri->t203_timer);
pri->t203_timer = 0;
}
/* Check this so that we don't try to send frames while multi frame mode is down */
if (pri->q921_state == Q921_LINK_CONNECTION_ESTABLISHED) {
if (pri->debug & PRI_DEBUG_Q921_DUMP)
pri_message(pri, "Starting T_200 timer\n");
reschedule_t200(pri);
}
} else {
pri_error(pri, "!! Out of memory for Q.921 transmit\n");
return -1;
}
return 0;
}
static void t203_expire(void *vpri)
{
struct pri *pri = vpri;
if (pri->q921_state == Q921_LINK_CONNECTION_ESTABLISHED) {
if (pri->debug & PRI_DEBUG_Q921_DUMP)
pri_message(pri, "T203 counter expired, sending RR and scheduling T203 again\n");
/* Solicit an F-bit in the other's RR */
pri->solicitfbit = 1;
pri->retrans = 0;
q921_rr(pri, 1, 1);
/* Start timer T200 to resend our RR if we don't get it */
pri->t203_timer = pri_schedule_event(pri, pri->timers[PRI_TIMER_T200], t200_expire, pri);
} else {
if (pri->debug & PRI_DEBUG_Q921_DUMP) {
pri_message(pri,
"T203 counter expired in weird state %d on pri with SAPI/TEI of %d/%d\n",
pri->q921_state, pri->sapi, pri->tei);
}
pri->t203_timer = 0;
}
}
static pri_event *q921_handle_iframe(struct pri *pri, q921_i *i, int len)
{
int res;
pri_event *ev;
pri->solicitfbit = 0;
/* Make sure this is a valid packet */
if (i->n_s == pri->v_r) {
/* Increment next expected I-frame */
Q921_INC(pri->v_r);
/* Handle their ACK */
pri->sentrej = 0;
ev = q921_ack_rx(pri, i->n_r, 1);
if (ev)
return ev;
if (i->p_f) {
/* If the Poll/Final bit is set, immediate send the RR */
q921_rr(pri, 1, 0);
} else if (pri->busy || pri->retrans) {
q921_rr(pri, 0, 0);
}
/* Receive Q.931 data */
res = q931_receive(pri, (q931_h *)i->data, len - 4);
/* Send an RR if one wasn't sent already */
if (pri->v_na != pri->v_r)
q921_rr(pri, 0, 0);
if (res == -1) {
return NULL;
}
if (res & Q931_RES_HAVEEVENT)
return &pri->ev;
} else {
/* If we haven't already sent a reject, send it now, otherwise
we are obliged to RR */
if (!pri->sentrej)
q921_reject(pri, i->p_f);
else if (i->p_f)
q921_rr(pri, 1, 0);
}
return NULL;
}
void q921_dump(struct pri *pri, q921_h *h, int len, int showraw, int txrx)
{
int x;
char *type;
char direction_tag;
direction_tag = txrx ? '>' : '<';
if (showraw) {
char *buf = malloc(len * 3 + 1);
int buflen = 0;
if (buf) {
pri_message(pri, "\n");
for (x=0;x<len;x++)
buflen += sprintf(buf + buflen, "%02x ", h->raw[x]);
pri_message(pri, "%c [ %s]\n", direction_tag, buf);
free(buf);
}
}
pri_message(pri, "\n");
switch (h->h.data[0] & Q921_FRAMETYPE_MASK) {
case 0:
case 2:
pri_message(pri, "%c Informational frame:\n", direction_tag);
break;
case 1:
pri_message(pri, "%c Supervisory frame:\n", direction_tag);
break;
case 3:
pri_message(pri, "%c Unnumbered frame:\n", direction_tag);
break;
}
pri_message(pri, "%c SAPI: %02d C/R: %d EA: %d\n",
direction_tag,
h->h.sapi,
h->h.c_r,
h->h.ea1);
pri_message(pri, "%c TEI: %03d EA: %d\n",
direction_tag,
h->h.tei,
h->h.ea2);
switch (h->h.data[0] & Q921_FRAMETYPE_MASK) {
case 0:
case 2:
/* Informational frame */
pri_message(pri,
"%c N(S): %03d 0: %d\n",
direction_tag,
h->i.n_s,
h->i.ft);
pri_message(pri,
"%c N(R): %03d P: %d\n",
direction_tag,
h->i.n_r,
h->i.p_f);
pri_message(pri,
"%c %d bytes of data\n",
direction_tag,
len - 4);
break;
case 1:
/* Supervisory frame */
type = "???";
switch (h->s.ss) {
case 0:
type = "RR (receive ready)";
break;
case 1:
type = "RNR (receive not ready)";
break;
case 2:
type = "REJ (reject)";
break;
}
pri_message(pri,
"%c Zero: %d S: %d 01: %d [ %s ]\n",
direction_tag,
h->s.x0,
h->s.ss,
h->s.ft,
type);
pri_message(pri,
"%c N(R): %03d P/F: %d\n",
direction_tag,
h->s.n_r,
h->s.p_f);
pri_message(pri,
"%c %d bytes of data\n",
direction_tag,
len - 4);
break;
case 3:
/* Unnumbered frame */
type = "???";
if (h->u.ft == 3) {
switch (h->u.m3) {
case 0:
if (h->u.m2 == 3)
type = "DM (disconnect mode)";
else if (h->u.m2 == 0)
type = "UI (unnumbered information)";
break;
case 2:
if (h->u.m2 == 0)
type = "DISC (disconnect)";
break;
case 3:
if (h->u.m2 == 3)
type = "SABME (set asynchronous balanced mode extended)";
else if (h->u.m2 == 0)
type = "UA (unnumbered acknowledgement)";
break;
case 4:
if (h->u.m2 == 1)
type = "FRMR (frame reject)";
break;
case 5:
if (h->u.m2 == 3)
type = "XID (exchange identification note)";
break;
}
}
pri_message(pri,
"%c M3: %d P/F: %d M2: %d 11: %d [ %s ]\n",
direction_tag,
h->u.m3,
h->u.p_f,
h->u.m2,
h->u.ft,
type);
pri_message(pri,
"%c %d bytes of data\n",
direction_tag,
len - 3);
break;
};
if ((h->u.ft == 3) && (h->u.m3 == 0) && (h->u.m2 == 0) && (h->u.data[0] == 0x0f)) {
int ri;
int tei;
ri = (h->u.data[1] << 8) | h->u.data[2];
tei = (h->u.data[4] >> 1);
/* TEI assignment related */
switch (h->u.data[3]) {
case Q921_TEI_IDENTITY_REQUEST:
type = "TEI Identity Request";
break;
case Q921_TEI_IDENTITY_ASSIGNED:
type = "TEI Identity Assigned";
break;
case Q921_TEI_IDENTITY_CHECK_REQUEST:
type = "TEI Identity Check Request";
break;
case Q921_TEI_IDENTITY_REMOVE:
type = "TEI Identity Remove";
break;
case Q921_TEI_IDENTITY_DENIED:
type = "TEI Identity Denied";
break;
case Q921_TEI_IDENTITY_CHECK_RESPONSE:
type = "TEI Identity Check Response";
break;
case Q921_TEI_IDENTITY_VERIFY:
type = "TEI Identity Verify";
break;
default:
type = "Unknown";
break;
}
pri_message(pri, "%c MDL Message: %s (%d)\n", direction_tag, type, h->u.data[3]);
pri_message(pri, "%c RI: %d\n", direction_tag, ri);
pri_message(pri, "%c Ai: %d E:%d\n", direction_tag, (h->u.data[4] >> 1) & 0x7f, h->u.data[4] & 1);
}
}
pri_event *q921_dchannel_up(struct pri *pri)
{
if (pri->tei == Q921_TEI_PRI) {
q921_reset(pri, 1);
} else {
q921_reset(pri, 0);
}
/* Stop any SABME retransmissions */
pri_schedule_del(pri, pri->sabme_timer);
pri->sabme_timer = 0;
/* Reset any rejects */
pri->sentrej = 0;
/* Go into connection established state */
if (pri->debug & PRI_DEBUG_Q921_STATE && pri->q921_state != Q921_LINK_CONNECTION_ESTABLISHED)
pri_message(pri, DBGHEAD "q921_state now is Q921_LINK_CONNECTION_ESTABLISHED\n", DBGINFO);
pri->q921_state = Q921_LINK_CONNECTION_ESTABLISHED;
/* Ensure that we do not have T200 or T203 running when the link comes up */
pri_schedule_del(pri, pri->t200_timer);
pri->t200_timer = 0;
/* Start the T203 timer */
pri_schedule_del(pri, pri->t203_timer);
pri->t203_timer = pri_schedule_event(pri, pri->timers[PRI_TIMER_T203], t203_expire, pri);
/* Notify Layer 3 */
q931_dl_indication(pri, PRI_EVENT_DCHAN_UP);
q921_send_queued_iframes(pri);
/* Report event that D-Channel is now up */
pri->ev.gen.e = PRI_EVENT_DCHAN_UP;
return &pri->ev;
}
pri_event *q921_dchannel_down(struct pri *pri)
{
/* Reset counters, reset sabme timer etc */
q921_reset(pri, 1);
/* Notify Layer 3 */
q931_dl_indication(pri, PRI_EVENT_DCHAN_DOWN);
/* Report event that D-Channel is now down */
pri->ev.gen.e = PRI_EVENT_DCHAN_DOWN;
return &pri->ev;
}
void q921_reset(struct pri *pri, int reset_iqueue)
{
/* Having gotten a SABME we MUST reset our entire state */
if (reset_iqueue)
pri->v_s = 0;
pri->v_a = 0;
pri->v_r = 0;
pri->v_na = 0;
pri->window = pri->timers[PRI_TIMER_K];
pri->windowlen = 0;
pri_schedule_del(pri, pri->sabme_timer);
pri_schedule_del(pri, pri->t203_timer);
pri_schedule_del(pri, pri->t200_timer);
pri->sabme_timer = 0;
pri->sabme_count = 0;
pri->t203_timer = 0;
pri->t200_timer = 0;
pri->busy = 0;
pri->solicitfbit = 0;
if (pri->debug & PRI_DEBUG_Q921_STATE && pri->q921_state != Q921_LINK_CONNECTION_RELEASED)
pri_message(pri, DBGHEAD "q921_state now is Q921_LINK_CONNECTION_RELEASED\n", DBGINFO);
pri->q921_state = Q921_LINK_CONNECTION_RELEASED;
pri->retrans = 0;
pri->sentrej = 0;
/* Discard anything waiting to go out */
if (reset_iqueue)
q921_discard_retransmissions(pri);
}
static void q921_tei_release_and_reacquire(struct pri *master)
{
/* Make sure the master is passed into this function */
q921_dchannel_down(master->subchannel);
__pri_free_tei(master->subchannel);
master->subchannel = NULL;
master->ev.gen.e = PRI_EVENT_DCHAN_DOWN;
master->schedev = 1;
q921_start(master, master->localtype == PRI_CPE);
}
static pri_event *q921_receive_MDL(struct pri *pri, q921_u *h, int len)
{
int ri;
struct pri *sub = pri;
int tei;
if (!BRI_NT_PTMP(pri) && !BRI_TE_PTMP(pri)) {
pri_error(pri, "Received MDL/TEI managemement message, but configured for mode other than PTMP!\n");
return NULL;
}
if (pri->debug & PRI_DEBUG_Q921_STATE)
pri_message(pri, "Received MDL message\n");
if (h->data[0] != 0x0f) {
pri_error(pri, "Received MDL with unsupported management entity %02x\n", h->data[0]);
return NULL;
}
if (!(h->data[4] & 0x01)) {
pri_error(pri, "Received MDL with multibyte TEI identifier\n");
return NULL;
}
ri = (h->data[1] << 8) | h->data[2];
tei = (h->data[4] >> 1);
switch(h->data[3]) {
case Q921_TEI_IDENTITY_REQUEST:
if (!BRI_NT_PTMP(pri)) {
return NULL;
}
if (tei != 127) {
pri_error(pri, "Received TEI identity request with invalid TEI %d\n", tei);
q921_send_tei(pri, Q921_TEI_IDENTITY_DENIED, ri, tei, 1);
}
tei = 64;
while (sub->subchannel) {
if (sub->subchannel->tei == tei)
++tei;
sub = sub->subchannel;
}
sub->subchannel = __pri_new_tei(-1, pri->localtype, pri->switchtype, pri, NULL, NULL, NULL, tei, 1);
if (!sub->subchannel) {
pri_error(pri, "Unable to allocate D-channel for new TEI %d\n", tei);
return NULL;
}
q921_send_tei(pri, Q921_TEI_IDENTITY_ASSIGNED, ri, tei, 1);
break;
case Q921_TEI_IDENTITY_ASSIGNED:
if (!BRI_TE_PTMP(pri))
return NULL;
if (ri != pri->ri) {
pri_message(pri, "TEI assignment received for invalid Ri %02x (our is %02x)\n", ri, pri->ri);
return NULL;
}
pri_schedule_del(pri, pri->t202_timer);
pri->t202_timer = 0;
if (pri->subchannel && (pri->subchannel->tei == tei)) {
pri_error(pri, "TEI already assigned (new is %d, current is %d)\n", tei, pri->subchannel->tei);
q921_tei_release_and_reacquire(pri);
return NULL;
}
pri_message(pri, "TEI assiged to %d\n", tei);
pri->subchannel = __pri_new_tei(-1, pri->localtype, pri->switchtype, pri, NULL, NULL, NULL, tei, 1);
if (!pri->subchannel) {
pri_error(pri, "Unable to allocate D-channel for new TEI %d\n", tei);
return NULL;
}
pri->q921_state = Q921_TEI_ASSIGNED;
break;
case Q921_TEI_IDENTITY_CHECK_REQUEST:
if (!BRI_TE_PTMP(pri))
return NULL;
/* We're assuming one TEI per PRI in TE PTMP mode */
/* If no subchannel (TEI) ignore */
if (!pri->subchannel)
return NULL;
/* If it's addressed to the group TEI or to our TEI specifically, we respond */
if ((tei == Q921_TEI_GROUP) || (tei == pri->subchannel->tei))
q921_send_tei(pri, Q921_TEI_IDENTITY_CHECK_RESPONSE, random() % 65535, pri->subchannel->tei, 1);
break;
case Q921_TEI_IDENTITY_REMOVE:
if (!BRI_TE_PTMP(pri))
return NULL;
/* XXX: Assuming multiframe mode has been disconnected already */
if (!pri->subchannel)
return NULL;
if ((tei == Q921_TEI_GROUP) || (tei == pri->subchannel->tei)) {
q921_tei_release_and_reacquire(pri);
}
}
return NULL; /* Do we need to return something??? */
}
static int is_command(struct pri *pri, q921_h *h)
{
int command =0;
int c_r = h->s.h.c_r;
if ((pri->localtype == PRI_NETWORK && c_r == 0) ||
(pri->localtype == PRI_CPE && c_r == 1))
command = 1;
return( command );
}
static pri_event *__q921_receive_qualified(struct pri *pri, q921_h *h, int len)
{
q921_frame *f;
pri_event *ev;
int sendnow;
switch(h->h.data[0] & Q921_FRAMETYPE_MASK) {
case 0:
case 2:
if (pri->q921_state != Q921_LINK_CONNECTION_ESTABLISHED) {
pri_error(pri, "!! Got I-frame while link state %d\n", pri->q921_state);
return NULL;
}
/* Informational frame */
if (len < 4) {
pri_error(pri, "!! Received short I-frame (expected 4, got %d)\n", len);
break;
}
/* T203 is rescheduled only on reception of I frames or S frames */
reschedule_t203(pri);
return q921_handle_iframe(pri, &h->i, len);
break;
case 1:
if (pri->q921_state != Q921_LINK_CONNECTION_ESTABLISHED) {
pri_error(pri, "!! Got S-frame while link down\n");
return NULL;
}
if (len < 4) {
pri_error(pri, "!! Received short S-frame (expected 4, got %d)\n", len);
break;
}
/* T203 is rescheduled only on reception of I frames or S frames */
reschedule_t203(pri);
switch(h->s.ss) {
case 0:
/* Receiver Ready */
pri->busy = 0;
/* Acknowledge frames as necessary */
ev = q921_ack_rx(pri, h->s.n_r, 1);
if (ev)
return ev;
if (is_command(pri, h))
pri->solicitfbit = 0;
if (h->s.p_f) {
/* If it's a p/f one then send back a RR in return with the p/f bit set */
if (!is_command(pri, h)) {
if (pri->debug & PRI_DEBUG_Q921_DUMP)
pri_message(pri, "-- Got RR response to our frame\n");
pri->retrans = 0;
} else {
if (pri->debug & PRI_DEBUG_Q921_DUMP)
pri_message(pri, "-- Unsolicited RR with P/F bit, responding\n");
q921_rr(pri, 1, 0);
}
}
break;
case 1:
/* Receiver not ready */
if (pri->debug & PRI_DEBUG_Q921_STATE)
pri_message(pri, "-- Got receiver not ready\n");
pri->busy = 1;
ev = q921_ack_rx(pri, h->s.n_r, 0);
if (ev)
return ev;
if (h->s.p_f && is_command(pri, h))
q921_rr(pri, 1, 0);
pri->solicitfbit = 1;
pri->retrans = 0;
if (pri->t203_timer) {
if (pri->debug & PRI_DEBUG_Q921_DUMP)
pri_message(pri, "Stopping T_203 timer\n");
pri_schedule_del(pri, pri->t203_timer);
pri->t203_timer = 0;
}
if (pri->debug & PRI_DEBUG_Q921_DUMP)
pri_message(pri, "Restarting T_200 timer\n");
reschedule_t200(pri);
break;
case 2:
/* Just retransmit */
if (pri->debug & PRI_DEBUG_Q921_STATE)
pri_message(pri, "-- Got reject requesting packet %d... Retransmitting.\n", h->s.n_r);
if (pri->busy && !is_command(pri, h))
pri->solicitfbit = 0;
pri->busy = 0;
if (is_command(pri, h) && h->s.p_f)
q921_rr(pri, 1, 0);
q921_ack_rx(pri, h->s.n_r, 0);
/*Resend only if we are in the Multiple Frame Established state or when
we are in the Time Recovery state and received responce with bit F=1*/
if ((pri->solicitfbit == 0) || (pri->solicitfbit && !is_command(pri, h) && h->s.p_f)) {
pri->solicitfbit = 0;
pri->retrans = 0;
sendnow = 0;
/* Resend I-frames starting from frame where f->h.n_s == h->s.n_r */
for (f = pri->txqueue; f && (f->h.n_s != h->s.n_r); f = f->next);
while (f) {
sendnow = 1;
if (f->transmitted || (!f->transmitted && (pri->windowlen < pri->window))) {
if (pri->debug & PRI_DEBUG_Q921_STATE)
pri_error(pri, "!! Got reject for frame %d, retransmitting frame %d now, updating n_r!\n", h->s.n_r, f->h.n_s);
f->h.n_r = pri->v_r;
f->h.p_f = 0;
if (!f->transmitted && (pri->windowlen < pri->window))
pri->windowlen++;
q921_transmit(pri, (q921_h *)(&f->h), f->len);
}
f = f->next;
}
if (!sendnow) {
if (pri->txqueue) {
/* This should never happen */
if (!h->s.p_f || h->s.n_r) {
pri_error(pri, "!! Got reject for frame %d, but we only have others!\n", h->s.n_r);
}
} else {
/* Hrm, we have nothing to send, but have been REJ'd. Reset v_a, v_s, etc */
pri_error(pri, "!! Got reject for frame %d, but we have nothing -- resetting!\n", h->s.n_r);
pri->v_a = h->s.n_r;
pri->v_s = h->s.n_r;
}
}
/* Reset t200 timer if it was somehow going */
pri_schedule_del(pri, pri->t200_timer);
pri->t200_timer = 0;
/* Reset and restart t203 timer */
reschedule_t203(pri);
}
break;
default:
pri_error(pri, "!! XXX Unknown Supervisory frame ss=0x%02x,pf=%02xnr=%02x vs=%02x, va=%02x XXX\n", h->s.ss, h->s.p_f, h->s.n_r,
pri->v_s, pri->v_a);
}
break;
case 3:
if (len < 3) {
pri_error(pri, "!! Received short unnumbered frame\n");
break;
}
switch(h->u.m3) {
case 0:
if (h->u.m2 == 3) {
if (h->u.p_f) {
/* Section 5.7.1 says we should restart on receiving a DM response with the f-bit set to
one, but we wait T200 first */
if (pri->debug & (PRI_DEBUG_Q921_STATE | PRI_DEBUG_Q921_DUMP))
pri_message(pri, "-- Got DM Mode from peer.\n");
/* Disconnected mode, try again after T200 */
ev = q921_dchannel_down(pri);
q921_restart(pri, 0);
return ev;
} else {
if (pri->debug & PRI_DEBUG_Q921_DUMP)
pri_message(pri, "-- Ignoring unsolicited DM with p/f set to 0\n");
#if 0
/* Requesting that we start */
q921_restart(pri, 0);
#endif
}
break;
} else if (!h->u.m2) {
if ((pri->sapi == Q921_SAPI_LAYER2_MANAGEMENT) && (pri->tei == Q921_TEI_GROUP))
q921_receive_MDL(pri, (q921_u *)h, len);
else {
int res;
res = q931_receive(pri, (q931_h *) h->u.data, len - 3);
if (res == -1) {
return NULL;
}
if (res & Q931_RES_HAVEEVENT)
return &pri->ev;
}
}
break;
case 2:
if (pri->debug & (PRI_DEBUG_Q921_STATE | PRI_DEBUG_Q921_DUMP))
pri_message(pri, "-- Got Disconnect from peer.\n");
/* Acknowledge */
q921_send_ua(pri, h->u.p_f);
ev = q921_dchannel_down(pri);
if (BRI_TE_PTMP(pri) || PRI_PTP(pri)) {
q921_restart(pri, PRI_PTP(pri) ? 1 : 0);
}
return ev;
case 3:
if (h->u.m2 == 3) {
/* SABME */
if (pri->debug & (PRI_DEBUG_Q921_STATE | PRI_DEBUG_Q921_DUMP)) {
pri_message(pri, "-- Got SABME from %s peer.\n", h->h.c_r ? "network" : "cpe");
}
if (h->h.c_r) {
pri->remotetype = PRI_NETWORK;
if (pri->localtype == PRI_NETWORK) {
/* We can't both be networks */
return pri_mkerror(pri, "We think we're the network, but they think they're the network, too.");
}
} else {
pri->remotetype = PRI_CPE;
if (pri->localtype == PRI_CPE) {
/* We can't both be CPE */
return pri_mkerror(pri, "We think we're the CPE, but they think they're the CPE too.\n");
}
}
/* Send Unnumbered Acknowledgement */
q921_send_ua(pri, h->u.p_f);
return q921_dchannel_up(pri);
} else if (h->u.m2 == 0) {
/* It's a UA */
if (pri->q921_state == Q921_AWAITING_ESTABLISH) {
if (pri->debug & (PRI_DEBUG_Q921_STATE | PRI_DEBUG_Q921_DUMP)) {
pri_message(pri, "-- Got UA from %s peer Link up.\n", h->h.c_r ? "cpe" : "network");
}
return q921_dchannel_up(pri);
} else if ((pri->q921_state >= Q921_TEI_ASSIGNED) && pri->bri) {
/* Possible duplicate TEI assignment */
if (pri->master)
q921_tei_release_and_reacquire(pri->master);
else
pri_error(pri, "Huh!? no master found\n");
} else {
/* Since we're not in the AWAITING_ESTABLISH STATE, it's unsolicited */
pri_error(pri, "!! Got a UA, but i'm in state %d\n", pri->q921_state);
}
} else
pri_error(pri, "!! Weird frame received (m3=3, m2 = %d)\n", h->u.m2);
break;
case 4:
pri_error(pri, "!! Frame got rejected!\n");
break;
case 5:
pri_error(pri, "!! XID frames not supported\n");
break;
default:
pri_error(pri, "!! Don't know what to do with M3=%d u-frames\n", h->u.m3);
}
break;
}
return NULL;
}
static pri_event *q921_handle_unmatched_frame(struct pri *pri, q921_h *h, int len)
{
pri = PRI_MASTER(pri);
if (h->h.tei < 64) {
pri_error(pri, "Do not support manual TEI range. Discarding\n");
return NULL;
}
if (h->h.sapi != Q921_SAPI_CALL_CTRL) {
pri_error(pri, "Message with SAPI other than CALL CTRL is discarded\n");
return NULL;
}
if (pri->debug & PRI_DEBUG_Q921_DUMP) {
pri_message(pri,
"Could not find candidate subchannel for received frame with SAPI/TEI of %d/%d.\n",
h->h.sapi, h->h.tei);
pri_message(pri, "Sending TEI release, in order to re-establish TEI state\n");
}
/* Q.921 says we should send the remove message twice, in case of link corruption */
q921_send_tei(pri, Q921_TEI_IDENTITY_REMOVE, 0, h->h.tei, 1);
q921_send_tei(pri, Q921_TEI_IDENTITY_REMOVE, 0, h->h.tei, 1);
return NULL;
}
static pri_event *__q921_receive(struct pri *pri, q921_h *h, int len)
{
pri_event *ev;
/* Discard FCS */
len -= 2;
if (!pri->master && pri->debug & (PRI_DEBUG_Q921_DUMP | PRI_DEBUG_Q921_RAW))
q921_dump(pri, h, len, pri->debug & PRI_DEBUG_Q921_RAW, 0);
/* Check some reject conditions -- Start by rejecting improper ea's */
if (h->h.ea1 || !(h->h.ea2))
return NULL;
if (!((h->h.sapi == pri->sapi) && ((h->h.tei == pri->tei) || (h->h.tei == Q921_TEI_GROUP)))) {
/* Check for SAPIs we don't yet handle */
/* If it's not us, try any subchannels we have */
if (pri->subchannel)
return q921_receive(pri->subchannel, h, len + 2);
else {
/* This means we couldn't find a candidate subchannel for it...
* Time for some corrective action */
return q921_handle_unmatched_frame(pri, h, len);
}
}
if (pri->debug & PRI_DEBUG_Q921_DUMP)
pri_message(pri, "Handling message for SAPI/TEI=%d/%d\n", h->h.sapi, h->h.tei);
ev = __q921_receive_qualified(pri, h, len);
return ev;
}
pri_event *q921_receive(struct pri *pri, q921_h *h, int len)
{
pri_event *e;
e = __q921_receive(pri, h, len);
#ifdef LIBPRI_COUNTERS
pri->q921_rxcount++;
#endif
return e;
}
static void q921_restart(struct pri *pri, int now)
{
if (pri->q921_state != Q921_LINK_CONNECTION_RELEASED) {
pri_error(pri, "!! q921_start: Not in 'Link Connection Released' state\n");
return;
}
/* Reset our interface */
q921_reset(pri, 1);
/* Do the SABME XXX Maybe we should implement T_WAIT? XXX */
q921_send_sabme(pri, now);
}
void q921_start(struct pri *pri, int isCPE)
{
q921_reset(pri, 1);
if ((pri->sapi == Q921_SAPI_LAYER2_MANAGEMENT) && (pri->tei == Q921_TEI_GROUP)) {
pri->q921_state = Q921_DOWN;
if (isCPE)
q921_tei_request(pri);
} else {
q921_send_sabme(pri, isCPE);
}
}
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