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libpri/q921.c
Matthew Fredrickson 3a1739883b There are two changes in this commit that are bug fixes for various Q.921 issues found in internal testing. 
Both were exposed/introduced by the TBR4 compliance patch for bug #12861, in changing how retransmissions and in how
the transmission queue was maintained.  TX-RX message flow and acknowledgement was severely restricted,
since the patch changed the behavior so that pending untransmitted frames would not actually be send until
the next RR was received in normal circumstances, or REJ when a reject frame was received.  On busy links,
this can severly limit the amount of useful traffic that is sent, and can slow down message transmission.

Until someone can point out where in Q.921 it is mandated for us to wait for RR frames to start sending
untransmitted messages, the first change is to allow us to send untransmitted frames when we receive new
I frames as well, with updated N(R).

The other bug fixed is a situation caused by the restricted traffic flow, if an outside process tries to send
an I-frame asynchronous to an RR frame, when the transmit window was previously closed and then opened up but 
an RR has not been received yet.  A bug was found with the integration of the old transmit code with the new reject 
handling code which caused the new frame to be sent immediately, regardless if there were any pending untransmitted 
I-frames in the queue to be sent and causing an out of order I-frame to be sent to the other side.  This bug is 
also fixed in this patch.


git-svn-id: https://origsvn.digium.com/svn/libpri/branches/1.4@859 2fbb986a-6c06-0410-b554-c9c1f0a7f128
2009-06-09 19:47:05 +00:00

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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 <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);
if (pri->t202_timer)
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 = 0;
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");
if (pri->t200_timer)
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");
if (pri->t203_timer)
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 */
if (pri->t200_timer) {
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_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->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\n", pri->q921_state);
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) {
for (x=0;x<len;x++)
buflen += sprintf(buf + buflen, "%02x ", h->raw[x]);
pri_message(pri, "\n%c [ %s]\n", direction_tag, buf);
free(buf);
}
}
switch (h->h.data[0] & Q921_FRAMETYPE_MASK) {
case 0:
case 2:
pri_message(pri, "\n%c Informational frame:\n", direction_tag);
break;
case 1:
pri_message(pri, "\n%c Supervisory frame:\n", direction_tag);
break;
case 3:
pri_message(pri, "\n%c Unnumbered frame:\n", direction_tag);
break;
}
pri_message(pri,
"%c SAPI: %02d C/R: %d EA: %d\n"
"%c TEI: %03d EA: %d\n",
direction_tag,
h->h.sapi,
h->h.c_r,
h->h.ea1,
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"
"%c N(R): %03d P: %d\n"
"%c %d bytes of data\n",
direction_tag,
h->i.n_s,
h->i.ft,
direction_tag,
h->i.n_r,
h->i.p_f,
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"
"%c N(R): %03d P/F: %d\n"
"%c %d bytes of data\n",
direction_tag,
h->s.x0,
h->s.ss,
h->s.ft,
type,
direction_tag,
h->s.n_r,
h->s.p_f,
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"
"%c %d bytes of data\n",
direction_tag,
h->u.m3,
h->u.p_f,
h->u.m2,
h->u.ft,
type,
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)
{
/* Stop any SABME retransmissions */
if (pri->sabme_timer) {
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;
/* Start the 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);
/* 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)
{
/* Having gotten a SABME we MUST reset our entire state */
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;
if (pri->sabme_timer)
pri_schedule_del(pri, pri->sabme_timer);
if (pri->t203_timer)
pri_schedule_del(pri, pri->t203_timer);
if (pri->t200_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 */
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;
int tei;
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 (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);
}
/* Go to master */
for (sub = pri; sub->master; sub = sub->master);
tei = 64;
/*! \todo XXX Error: The following loop never terminates! */
while(sub->subchannel) {
if(sub->subchannel->tei == tei)
++tei;
}
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 (ri != pri->ri) {
pri_message(pri, "TEI assignment received for invalid Ri %02x (our is %02x)\n", ri, pri->ri);
return NULL;
}
if (pri->t202_timer) {
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:
/* 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:
/* 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;
}
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;
}
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 */
if (pri->t200_timer) {
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);
q921_restart(pri, 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_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 0 /* Will be rejected by subchannel analyzis */
/* Check for broadcasts - not yet handled */
if (h->h.tei == Q921_TEI_GROUP)
return NULL;
#endif
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 {
return NULL;
}
}
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);
reschedule_t203(pri);
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);
/* 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);
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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