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libpri/q921.c
Matthew Fredrickson 424fa816e3 Send RR as command instead of response when T200 expires after receiving RNR. 
git-svn-id: https://origsvn.digium.com/svn/libpri/trunk@279 2fbb986a-6c06-0410-b554-c9c1f0a7f128
2005-12-06 21:18:44 +00:00

952 lines
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/*
* libpri: An implementation of Primary Rate ISDN
*
* Written by Mark Spencer <markster@digium.com>
*
* Copyright (C) 2001-2005, Digium
* All Rights Reserved.
*
* 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., 675 Mass Ave, Cambridge, MA 02139, USA.
*
*/
#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 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)
return q921_transmit(pri->master, h, len);
#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)
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;
}
reschedule_t203(pri);
return 0;
}
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_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->debug & PRI_DEBUG_Q921_STATE)
pri_message(pri, "Sending Set Asynchronous Balanced Mode Extended\n");
q921_transmit(pri, &h, 3);
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_STATE)
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--;
/* Search for something to send */
f = pri->txqueue;
while(f) {
if (!f->transmitted) {
/* Send it now... */
if (pri->debug & PRI_DEBUG_Q921_STATE)
pri_message(pri, "-- Finally transmitting %d, since window opened up\n", f->h.n_s);
f->transmitted++;
pri->windowlen++;
f->h.n_r = pri->v_r;
q921_transmit(pri, (q921_h *)(&f->h), f->len);
break;
}
f = f->next;
}
return 1;
}
prev = f;
f = f->next;
}
return 0;
}
static void t203_expire(void *);
static void t200_expire(void *);
static pri_event *q921_dchannel_down(struct pri *pri);
static void reschedule_t203(struct pri *pri)
{
if (pri->t203_timer) {
pri_schedule_del(pri, pri->t203_timer);
if (pri->debug & PRI_DEBUG_Q921_STATE)
pri_message(pri, "-- Restarting 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);
}
}
static pri_event *q921_ack_rx(struct pri *pri, int ack)
{
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_STATE)
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_STATE)
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_STATE)
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->debug & PRI_DEBUG_Q921_STATE)
pri_message(pri, "-- Something left to transmit (%d), restarting T200 counter\n", pri->txqueue->h.n_s);
if (!pri->t200_timer)
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, "-- 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_STATE)
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_STATE)
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;
if (pri->txqueue) {
/* Retransmit first packet in the queue, setting the poll bit */
if (pri->debug & PRI_DEBUG_Q921_STATE)
pri_message(pri, "-- T200 counter expired, What to do...\n");
/* Force Poll bit */
pri->txqueue->h.p_f = 1;
/* Update nr */
pri->txqueue->h.n_r = pri->v_r;
pri->v_na = pri->v_r;
pri->solicitfbit = 1;
pri->retrans++;
/* Up to three retransmissions */
if (pri->retrans < pri->timers[PRI_TIMER_N200]) {
/* Reschedule t200_timer */
if (pri->debug & PRI_DEBUG_Q921_STATE)
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");
q921_transmit(pri, (q921_h *)&pri->txqueue->h, pri->txqueue->len);
}
if (pri->debug & PRI_DEBUG_Q921_STATE)
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");
pri->q921_state = Q921_LINK_CONNECTION_RELEASED;
pri->t200_timer = 0;
q921_dchannel_down(pri);
q921_start(pri, 1);
pri->schedev = 1;
}
} else if (pri->solicitfbit) {
if (pri->debug & PRI_DEBUG_Q921_STATE)
pri_message(pri, "-- Retrying poll with f-bit\n");
pri->retrans++;
if (pri->retrans < pri->timers[PRI_TIMER_N200]) {
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");
pri->q921_state = Q921_LINK_CONNECTION_RELEASED;
pri->t200_timer = 0;
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 = malloc(sizeof(q921_frame) + len + 2);
if (f) {
memset(f,0,sizeof(q921_frame) + len + 2);
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->retrans && !pri->busy) {
if (pri->windowlen < pri->window) {
pri->windowlen++;
q921_transmit(pri, (q921_h *)(&f->h), f->len);
f->transmitted++;
} else {
if (pri->debug & PRI_DEBUG_Q921_STATE)
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_STATE)
pri_message(pri, "Stopping T_203 timer\n");
pri_schedule_del(pri, pri->t203_timer);
pri->t203_timer = 0;
}
if (!pri->t200_timer) {
if (pri->debug & PRI_DEBUG_Q921_STATE)
pri_message(pri, "Starting T_200 timer\n");
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, "T_200 timer already going (%d)\n", pri->t200_timer);
} 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_STATE)
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_STATE)
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;
/* 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);
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) {
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;
};
}
static pri_event *q921_dchannel_up(struct pri *pri)
{
/* Reset counters, etc */
q921_reset(pri);
/* 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 */
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);
/* Report event that D-Channel is now up */
pri->ev.gen.e = PRI_EVENT_DCHAN_UP;
return &pri->ev;
}
static pri_event *q921_dchannel_down(struct pri *pri)
{
/* Reset counters, reset sabme timer etc */
q921_reset(pri);
/* Report event that D-Channel is now up */
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;
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->t203_timer = 0;
pri->t200_timer = 0;
pri->busy = 0;
pri->solicitfbit = 0;
pri->q921_state = Q921_LINK_CONNECTION_RELEASED;
pri->retrans = 0;
pri->sentrej = 0;
/* Discard anything waiting to go out */
q921_discard_retransmissions(pri);
}
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);
if (ev)
return ev;
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 (pri->solicitfbit) {
if (pri->debug & PRI_DEBUG_Q921_STATE)
pri_message(pri, "-- Got RR response to our frame\n");
} else {
if (pri->debug & PRI_DEBUG_Q921_STATE)
pri_message(pri, "-- Unsolicited RR with P/F bit, responding\n");
q921_rr(pri, 1, 0);
}
pri->solicitfbit = 0;
}
break;
case 1:
/* Receiver not ready */
if (pri->debug & PRI_DEBUG_Q921_STATE)
pri_message(pri, "-- Got receiver not ready\n");
if(h->s.p_f) {
/* Send RR if poll bit set */
q921_rr(pri, h->s.p_f, 0);
}
pri->busy = 1;
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 (h->s.p_f) {
/* If it has the poll bit set, send an appropriate supervisory response */
q921_rr(pri, 1, 0);
}
sendnow = 0;
/* Resend the proper I-frame */
for(f=pri->txqueue;f;f=f->next) {
if ((sendnow || (f->h.n_s == h->s.n_r)) && f->transmitted) {
/* Matches the request, or follows in our window, and has
already been transmitted. */
sendnow = 1;
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;
q921_transmit(pri, (q921_h *)(&f->h), f->len);
}
}
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 */
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);
}
}
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_message(pri, "-- Got DM Mode from peer.\n");
/* Disconnected mode, try again after T200 */
ev = q921_dchannel_down(pri);
q921_start(pri, 0);
return ev;
} else {
if (pri->debug & PRI_DEBUG_Q921_STATE)
pri_message(pri, "-- Ignoring unsolicited DM with p/f set to 0\n");
#if 0
/* Requesting that we start */
q921_start(pri, 0);
#endif
}
break;
} else if (!h->u.m2) {
pri_message(pri, "XXX Unnumbered Information not implemented XXX\n");
}
break;
case 2:
if (pri->debug & PRI_DEBUG_Q921_STATE)
pri_message(pri, "-- Got Disconnect from peer.\n");
/* Acknowledge */
q921_send_ua(pri, h->u.p_f);
ev = q921_dchannel_down(pri);
q921_start(pri, 0);
return ev;
case 3:
if (h->u.m2 == 3) {
/* SABME */
if (pri->debug & PRI_DEBUG_Q921_STATE) {
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_message(pri, "-- Got UA from %s peer Link up.\n", h->h.c_r ? "cpe" : "network");
}
return q921_dchannel_up(pri);
} else
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)
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;
/* Check for broadcasts - not yet handled */
if (h->h.tei == Q921_TEI_GROUP)
return NULL;
/* Check for SAPIs we don't yet handle */
if ((h->h.sapi != pri->sapi) || (h->h.tei != pri->tei)) {
#ifdef PROCESS_SUBCHANNELS
/* If it's not us, try any subchannels we have */
if (pri->subchannel)
return q921_receive(pri->subchannel, h, len + 2);
else
#endif
return NULL;
}
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;
}
void q921_start(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);
}
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