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/*
* SpanDSP - a series of DSP components for telephony
*
* v42.c
*
* Written by Steve Underwood <steveu@coppice.org>
*
* Copyright (C) 2004, 2011 Steve Underwood
*
* All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License version 2.1,
* as published by the Free Software Foundation.
*
* 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
/* THIS IS A WORK IN PROGRESS. IT IS NOT FINISHED. */
/*! \file */
#if defined(HAVE_CONFIG_H)
#include "config.h"
#endif
#include <stdio.h>
#include <stdlib.h>
#include <inttypes.h>
#include <string.h>
#include <errno.h>
#include <fcntl.h>
#include <ctype.h>
#if defined(HAVE_STDBOOL_H)
#include <stdbool.h>
#else
#include "spandsp/stdbool.h"
#endif
#include <assert.h>
#include "spandsp/telephony.h"
#include "spandsp/alloc.h"
#include "spandsp/logging.h"
#include "spandsp/bit_operations.h"
#include "spandsp/async.h"
#include "spandsp/hdlc.h"
#include "spandsp/v42.h"
#include "spandsp/private/logging.h"
#include "spandsp/private/hdlc.h"
#include "spandsp/private/v42.h"
/* Detection phase timer */
#define T_400 750
/* Acknowledgement timer - 1 second between SABME's */
#define T_401 1000
/* Replay delay timer (optional) */
#define T_402 1000
/* Inactivity timer (optional). No default - use 10 seconds with no packets */
#define T_403 10000
#define LAPM_DLCI_DTE_TO_DTE 0
#define LAPM_DLCI_LAYER2_MANAGEMENT 63
#define elements(a) (sizeof(a)/sizeof((a)[0]))
/* LAPM definitions */
#define LAPM_FRAMETYPE_MASK 0x03
enum
{
LAPM_FRAMETYPE_I = 0x00,
LAPM_FRAMETYPE_I_ALT = 0x02,
LAPM_FRAMETYPE_S = 0x01,
LAPM_FRAMETYPE_U = 0x03
};
/* Supervisory headers */
enum
{
LAPM_S_RR = 0x00, /* cr */
LAPM_S_RNR = 0x04, /* cr */
LAPM_S_REJ = 0x08, /* cr */
LAPM_S_SREJ = 0x0C /* cr */
};
#define LAPM_S_PF 0x01
/* Unnumbered headers */
enum
{
LAPM_U_UI = 0x00, /* cr */
LAPM_U_DM = 0x0C, /* r */
LAPM_U_DISC = 0x40, /* c */
LAPM_U_UA = 0x60, /* r */
LAPM_U_SABME = 0x6C, /* c */
LAPM_U_FRMR = 0x84, /* r */
LAPM_U_XID = 0xAC, /* cr */
LAPM_U_TEST = 0xE0 /* c */
};
#define LAPM_U_PF 0x10
/* XID sub-field definitions */
#define FI_GENERAL 0x82
#define GI_PARAM_NEGOTIATION 0x80
#define GI_PRIVATE_NEGOTIATION 0xF0
#define GI_USER_DATA 0xFF
/* Param negotiation (Table 11a/V.42) */
enum
{
PI_HDLC_OPTIONAL_FUNCTIONS = 0x03,
PI_TX_INFO_MAXSIZE = 0x05,
PI_RX_INFO_MAXSIZE = 0x06,
PI_TX_WINDOW_SIZE = 0x07,
PI_RX_WINDOW_SIZE = 0x08
};
/* Private param negotiation (Table 11b/V.42) */
enum
{
PI_PARAMETER_SET_ID = 0x00,
PI_V42BIS_COMPRESSION_REQUEST = 0x01,
PI_V42BIS_NUM_CODEWORDS = 0x02,
PI_V42BIS_MAX_STRING_LENGTH = 0x03
};
#define LAPM_DLCI_DTE_TO_DTE 0
#define LAPM_DLCI_LAYER2_MANAGEMENT 63
/* Type definitions */
enum
{
LAPM_DETECT = 0,
LAPM_IDLE = 1,
LAPM_ESTABLISH = 2,
LAPM_DATA = 3,
LAPM_RELEASE = 4,
LAPM_SIGNAL = 5,
LAPM_SETPARM = 6,
LAPM_TEST = 7,
LAPM_V42_UNSUPPORTED = 8
};
/* Prototypes */
static int lapm_connect(v42_state_t *ss);
static int lapm_disconnect(v42_state_t *s);
static void reset_lapm(v42_state_t *s);
static void lapm_hdlc_underflow(void *user_data);
static int lapm_config(v42_state_t *ss);
SPAN_DECLARE(const char *) lapm_status_to_str(int status)
{
switch (status)
{
case LAPM_DETECT:
return "LAPM_DETECT";
case LAPM_IDLE:
return "LAPM_IDLE";
case LAPM_ESTABLISH:
return "LAPM_ESTABLISH";
case LAPM_DATA:
return "LAPM_DATA";
case LAPM_RELEASE:
return "LAPM_RELEASE";
case LAPM_SIGNAL:
return "LAPM_SIGNAL";
case LAPM_SETPARM:
return "LAPM_SETPARM";
case LAPM_TEST:
return "LAPM_TEST";
case LAPM_V42_UNSUPPORTED:
return "LAPM_V42_UNSUPPORTED";
}
/*endswitch*/
return "???";
}
/*- End of function --------------------------------------------------------*/
static void report_rx_status_change(v42_state_t *s, int status)
{
if (s->lapm.status_handler)
s->lapm.status_handler(s->lapm.status_user_data, status);
else if (s->lapm.iframe_put)
s->lapm.iframe_put(s->lapm.iframe_put_user_data, NULL, status);
}
/*- End of function --------------------------------------------------------*/
static inline uint32_t pack_value(const uint8_t *buf, int len)
{
uint32_t val;
val = 0;
while (len--)
{
val <<= 8;
val |= *buf++;
}
return val;
}
/*- End of function --------------------------------------------------------*/
static inline v42_frame_t *get_next_free_ctrl_frame(lapm_state_t *s)
{
v42_frame_t *f;
int ctrl_put_next;
if ((ctrl_put_next = s->ctrl_put + 1) >= V42_CTRL_FRAMES)
ctrl_put_next = 0;
if (ctrl_put_next == s->ctrl_get)
return NULL;
f = &s->ctrl_buf[s->ctrl_put];
s->ctrl_put = ctrl_put_next;
return f;
}
/*- End of function --------------------------------------------------------*/
static int tx_unnumbered_frame(lapm_state_t *s, uint8_t addr, uint8_t ctrl, uint8_t *info, int len)
{
v42_frame_t *f;
uint8_t *buf;
if ((f = get_next_free_ctrl_frame(s)) == NULL)
return -1;
buf = f->buf;
buf[0] = addr;
buf[1] = LAPM_FRAMETYPE_U | ctrl;
f->len = 2;
if (info && len)
{
memcpy(&buf[f->len], info, len);
f->len += len;
}
return 0;
}
/*- End of function --------------------------------------------------------*/
static int tx_supervisory_frame(lapm_state_t *s, uint8_t addr, uint8_t ctrl, uint8_t pf_mask)
{
v42_frame_t *f;
uint8_t *buf;
if ((f = get_next_free_ctrl_frame(s)) == NULL)
return -1;
buf = f->buf;
buf[0] = addr;
buf[1] = LAPM_FRAMETYPE_S | ctrl;
buf[2] = (s->vr << 1) | pf_mask;
f->len = 3;
return 0;
}
/*- End of function --------------------------------------------------------*/
static __inline__ int set_param(int param, int value, int def)
{
if ((value < def && param >= def) || (value >= def && param < def))
return def;
if ((value < def && param < value) || (value >= def && param > value))
return value;
return param;
}
/*- End of function --------------------------------------------------------*/
static int receive_xid(v42_state_t *ss, const uint8_t *frame, int len)
{
lapm_state_t *s;
v42_config_parameters_t config;
const uint8_t *buf;
uint8_t group_id;
uint16_t group_len;
uint32_t param_val;
uint8_t param_id;
uint8_t param_len;
s = &ss->lapm;
if (frame[2] != FI_GENERAL)
return -1;
memset(&config, 0, sizeof(config));
/* Skip the header octets */
frame += 3;
len -= 3;
while (len > 0)
{
group_id = frame[0];
group_len = frame[1];
group_len = (group_len << 8) | frame[2];
frame += 3;
len -= (3 + group_len);
if (len < 0)
break;
buf = frame;
frame += group_len;
switch (group_id)
{
case GI_PARAM_NEGOTIATION:
while (group_len > 0)
{
param_id = buf[0];
param_len = buf[1];
buf += 2;
if (group_len < (2 + param_len))
break;
group_len -= (2 + param_len);
switch (param_id)
{
case PI_HDLC_OPTIONAL_FUNCTIONS:
/* TODO: param_val is never used right now. */
//param_val = pack_value(buf, param_len);
break;
case PI_TX_INFO_MAXSIZE:
param_val = pack_value(buf, param_len);
param_val >>= 3;
config.v42_tx_n401 =
s->tx_n401 = set_param(s->tx_n401, param_val, ss->config.v42_tx_n401);
break;
case PI_RX_INFO_MAXSIZE:
param_val = pack_value(buf, param_len);
param_val >>= 3;
config.v42_rx_n401 =
s->rx_n401 = set_param(s->rx_n401, param_val, ss->config.v42_rx_n401);
break;
case PI_TX_WINDOW_SIZE:
param_val = pack_value(buf, param_len);
config.v42_tx_window_size_k =
s->tx_window_size_k = set_param(s->tx_window_size_k, param_val, ss->config.v42_tx_window_size_k);
break;
case PI_RX_WINDOW_SIZE:
param_val = pack_value(buf, param_len);
config.v42_rx_window_size_k =
s->rx_window_size_k = set_param(s->rx_window_size_k, param_val, ss->config.v42_rx_window_size_k);
break;
default:
break;
}
buf += param_len;
}
break;
case GI_PRIVATE_NEGOTIATION:
while (group_len > 0)
{
param_id = buf[0];
param_len = buf[1];
buf += 2;
if (group_len < 2 + param_len)
break;
group_len -= (2 + param_len);
switch (param_id)
{
case PI_PARAMETER_SET_ID:
/* This might be worth monitoring, but it doesn't serve mnuch other purpose */
break;
case PI_V42BIS_COMPRESSION_REQUEST:
config.comp = pack_value(buf, param_len);
break;
case PI_V42BIS_NUM_CODEWORDS:
config.comp_dict_size = pack_value(buf, param_len);
break;
case PI_V42BIS_MAX_STRING_LENGTH:
config.comp_max_string = pack_value(buf, param_len);
break;
default:
break;
}
buf += param_len;
}
break;
default:
break;
}
}
//v42_update_config(ss, &config);
return 0;
}
/*- End of function --------------------------------------------------------*/
static void transmit_xid(v42_state_t *ss, uint8_t addr)
{
lapm_state_t *s;
uint8_t *buf;
int len;
int group_len;
uint32_t param_val;
v42_frame_t *f;
s = &ss->lapm;
if ((f = get_next_free_ctrl_frame(s)) == NULL)
return;
buf = f->buf;
len = 0;
/* Figure 11/V.42 */
*buf++ = addr;
*buf++ = LAPM_U_XID | LAPM_FRAMETYPE_U;
/* Format identifier subfield */
*buf++ = FI_GENERAL;
len += 3;
/* Parameter negotiation group */
group_len = 20;
*buf++ = GI_PARAM_NEGOTIATION;
*buf++ = (group_len >> 8) & 0xFF;
*buf++ = group_len & 0xFF;
len += 3;
/* For conformance with the encoding rules in ISO/IEC 8885, the transmitter of an XID command frame shall
set bit positions 2, 4, 8, 9, 12 and 16 to 1. (Table 11a/V.42)
Optional bits are:
3 Selective retransmission procedure (SREJ frame) single I frame request
14 Loop-back test procedure (TEST frame)
17
Extended FCS procedure (32-bit FCS)
24 Selective retransmission procedure (SREJ frame) multiple I frame request with span list
capability. */
*buf++ = PI_HDLC_OPTIONAL_FUNCTIONS;
*buf++ = 4;
*buf++ = 0x8A; /* Bits 2, 4, and 8 set */
*buf++ = 0x89; /* Bits 9, 12, and 16 set */
*buf++ = 0x00;
*buf++ = 0x00;
/* Send the maximum as a number of bits, rather than octets */
param_val = ss->config.v42_tx_n401 << 3;
*buf++ = PI_TX_INFO_MAXSIZE;
*buf++ = 2;
*buf++ = (param_val >> 8) & 0xFF;
*buf++ = (param_val & 0xFF);
/* Send the maximum as a number of bits, rather than octets */
param_val = ss->config.v42_rx_n401 << 3;
*buf++ = PI_RX_INFO_MAXSIZE;
*buf++ = 2;
*buf++ = (param_val >> 8) & 0xFF;
*buf++ = (param_val & 0xFF);
*buf++ = PI_TX_WINDOW_SIZE;
*buf++ = 1;
*buf++ = ss->config.v42_tx_window_size_k;
*buf++ = PI_RX_WINDOW_SIZE;
*buf++ = 1;
*buf++ = ss->config.v42_rx_window_size_k;
len += group_len;
if (ss->config.comp)
{
/* Private parameter negotiation group */
group_len = 15;
*buf++ = GI_PRIVATE_NEGOTIATION;
*buf++ = (group_len >> 8) & 0xFF;
*buf++ = group_len & 0xFF;
len += 3;
/* Private parameter for V.42 (ASCII for V42). V.42 says ".42", but V.42bis says "V42",
and that seems to be what should be used. */
*buf++ = PI_PARAMETER_SET_ID;
*buf++ = 3;
*buf++ = 'V';
*buf++ = '4';
*buf++ = '2';
/* V.42bis P0
00 Compression in neither direction (default);
01 Negotiation initiator-responder direction only;
10 Negotiation responder-initiator direction only;
11 Both directions. */
*buf++ = PI_V42BIS_COMPRESSION_REQUEST;
*buf++ = 1;
*buf++ = ss->config.comp;
/* V.42bis P1 */
param_val = ss->config.comp_dict_size;
*buf++ = PI_V42BIS_NUM_CODEWORDS;
*buf++ = 2;
*buf++ = (param_val >> 8) & 0xFF;
*buf++ = param_val & 0xFF;
/* V.42bis P2 */
*buf++ = PI_V42BIS_MAX_STRING_LENGTH;
*buf++ = 1;
*buf++ = ss->config.comp_max_string;
len += group_len;
}
f->len = len;
}
/*- End of function --------------------------------------------------------*/
static int ms_to_bits(v42_state_t *s, int time)
{
return ((time*s->tx_bit_rate)/1000);
}
/*- End of function --------------------------------------------------------*/
static void t400_expired(v42_state_t *ss)
{
/* Give up trying to detect a V.42 capable peer. */
ss->bit_timer = 0;
ss->lapm.state = LAPM_V42_UNSUPPORTED;
report_rx_status_change(ss, ss->lapm.state);
}
/*- End of function --------------------------------------------------------*/
static __inline__ void t400_start(v42_state_t *s)
{
s->bit_timer = ms_to_bits(s, T_400);
s->bit_timer_func = t400_expired;
}
/*- End of function --------------------------------------------------------*/
static __inline__ void t400_stop(v42_state_t *s)
{
s->bit_timer = 0;
}
/*- End of function --------------------------------------------------------*/
static void t401_expired(v42_state_t *ss)
{
lapm_state_t *s;
span_log(&ss->logging, SPAN_LOG_FLOW, "T.401 expired\n");
s = &ss->lapm;
if (s->retry_count > V42_DEFAULT_N_400)
{
s->retry_count = 0;
switch (s->state)
{
case LAPM_ESTABLISH:
case LAPM_RELEASE:
s->state = LAPM_IDLE;
report_rx_status_change(ss, SIG_STATUS_LINK_DISCONNECTED);
break;
case LAPM_DATA:
lapm_disconnect(ss);
break;
}
return ;
}
s->retry_count++;
if (s->configuring)
{
transmit_xid(ss, s->cmd_addr);
}
else
{
switch (s->state)
{
case LAPM_ESTABLISH:
tx_unnumbered_frame(s, s->cmd_addr, LAPM_U_SABME | LAPM_U_PF, NULL, 0);
break;
case LAPM_RELEASE:
tx_unnumbered_frame(s, s->cmd_addr, LAPM_U_DISC | LAPM_U_PF, NULL, 0);
break;
case LAPM_DATA:
tx_supervisory_frame(s, s->cmd_addr, (s->local_busy) ? LAPM_S_RNR : LAPM_S_RR, 1);
break;
}
}
ss->bit_timer = ms_to_bits(ss, T_401);
ss->bit_timer_func = t401_expired;
}
/*- End of function --------------------------------------------------------*/
static __inline__ void t401_start(v42_state_t *s)
{
s->bit_timer = ms_to_bits(s, T_401);
s->bit_timer_func = t401_expired;
s->lapm.retry_count = 0;
}
/*- End of function --------------------------------------------------------*/
static __inline__ void t401_stop(v42_state_t *s)
{
s->bit_timer = 0;
s->lapm.retry_count = 0;
}
/*- End of function --------------------------------------------------------*/
static void t403_expired(v42_state_t *ss)
{
lapm_state_t *s;
span_log(&ss->logging, SPAN_LOG_FLOW, "T.403 expired\n");
if (ss->lapm.state != LAPM_DATA)
return;
s = &ss->lapm;
tx_supervisory_frame(s, s->cmd_addr, (ss->lapm.local_busy) ? LAPM_S_RNR : LAPM_S_RR, 1);
t401_start(ss);
ss->lapm.retry_count = 1;
}
/*- End of function --------------------------------------------------------*/
static __inline__ void t401_stop_t403_start(v42_state_t *s)
{
s->bit_timer = ms_to_bits(s, T_403);
s->bit_timer_func = t403_expired;
s->lapm.retry_count = 0;
}
/*- End of function --------------------------------------------------------*/
static void initiate_negotiation_expired(v42_state_t *s)
{
/* Timer service routine */
span_log(&s->logging, SPAN_LOG_FLOW, "Start negotiation\n");
lapm_config(s);
lapm_hdlc_underflow(s);
}
/*- End of function --------------------------------------------------------*/
static int tx_information_frame(v42_state_t *ss)
{
lapm_state_t *s;
v42_frame_t *f;
uint8_t *buf;
int n;
int info_put_next;
s = &ss->lapm;
if (s->far_busy || ((s->vs - s->va) & 0x7F) >= s->tx_window_size_k)
return false;
if (s->info_get != s->info_put)
return true;
if ((info_put_next = s->info_put + 1) >= V42_INFO_FRAMES)
info_put_next = 0;
if (info_put_next == s->info_get || info_put_next == s->info_acked)
return false;
f = &s->info_buf[s->info_put];
buf = f->buf;
if (s->iframe_get == NULL)
return false;
n = s->iframe_get(s->iframe_get_user_data, buf + 3, s->tx_n401);
if (n < 0)
{
/* Error */
report_rx_status_change(ss, SIG_STATUS_LINK_ERROR);
return false;
}
if (n == 0)
return false;
f->len = n + 3;
s->info_put = info_put_next;
return true;
}
/*- End of function --------------------------------------------------------*/
static void tx_information_rr_rnr_response(v42_state_t *ss, const uint8_t *frame, int len)
{
lapm_state_t *s;
s = &ss->lapm;
/* Respond with information frame, RR, or RNR, as appropriate */
/* p = 1 may be used for status checking */
if ((frame[2] & 0x1) || !tx_information_frame(ss))
tx_supervisory_frame(s, frame[0], (s->local_busy) ? LAPM_S_RNR : LAPM_S_RR, 1);
}
/*- End of function --------------------------------------------------------*/
static int reject_info(lapm_state_t *s)
{
uint8_t n;
/* Reject all non-acked frames */
if (s->state != LAPM_DATA)
return 0;
n = (s->vs - s->va) & 0x7F;
s->vs = s->va;
s->info_get = s->info_acked;
return n;
}
/*- End of function --------------------------------------------------------*/
static int ack_info(v42_state_t *ss, uint8_t nr)
{
lapm_state_t *s;
int n;
s = &ss->lapm;
/* Check that NR is valid - i.e. VA <= NR <= VS && VS-VA <= k */
if (!((((nr - s->va) & 0x7F) + ((s->vs - nr) & 0x7F)) <= s->tx_window_size_k
&&
((s->vs - s->va) & 0x7F) <= s->tx_window_size_k))
{
lapm_disconnect(ss);
return -1;
}
n = 0;
while (s->va != nr && s->info_acked != s->info_get)
{
if (++s->info_acked >= V42_INFO_FRAMES)
s->info_acked = 0;
s->va = (s->va + 1) & 0x7F;
n++;
}
if (n > 0 && s->retry_count == 0)
{
t401_stop_t403_start(ss);
/* 8.4.8 */
if (((s->vs - s->va) & 0x7F))
t401_start(ss);
}
return n;
}
/*- End of function --------------------------------------------------------*/
static int valid_data_state(v42_state_t *ss)
{
lapm_state_t *s;
s = &ss->lapm;
switch (s->state)
{
case LAPM_DETECT:
case LAPM_IDLE:
break;
case LAPM_ESTABLISH:
reset_lapm(ss);
s->state = LAPM_DATA;
report_rx_status_change(ss, SIG_STATUS_LINK_CONNECTED);
return 1;
case LAPM_DATA:
return 1;
case LAPM_RELEASE:
reset_lapm(ss);
s->state = LAPM_IDLE;
report_rx_status_change(ss, SIG_STATUS_LINK_DISCONNECTED);
break;
case LAPM_SIGNAL:
case LAPM_SETPARM:
case LAPM_TEST:
case LAPM_V42_UNSUPPORTED:
break;
}
return 0;
}
/*- End of function --------------------------------------------------------*/
static void receive_information_frame(v42_state_t *ss, const uint8_t *frame, int len)
{
lapm_state_t *s;
s = &ss->lapm;
if (!valid_data_state(ss))
return;
if (len > s->rx_n401 + 3)
return;
/* Ack I frames: NR - 1 */
ack_info(ss, frame[2] >> 1);
if (s->local_busy)
{
/* 8.4.7 */
if ((frame[2] & 0x1))
tx_supervisory_frame(s, s->rsp_addr, LAPM_S_RNR, 1);
return;
}
/* NS sequence error */
if ((frame[1] >> 1) != s->vr)
{
if (!s->rejected)
{
tx_supervisory_frame(s, s->rsp_addr, LAPM_S_REJ, (frame[2] & 0x1));
s->rejected = true;
}
return;
}
s->rejected = false;
s->iframe_put(s->iframe_put_user_data, frame + 3, len - 3);
/* Increment vr */
s->vr = (s->vr + 1) & 0x7F;
tx_information_rr_rnr_response(ss, frame, len);
}
/*- End of function --------------------------------------------------------*/
static void rx_supervisory_cmd_frame(v42_state_t *ss, const uint8_t *frame, int len)
{
lapm_state_t *s;
s = &ss->lapm;
/* If l->local_busy each RR,RNR,REJ with p=1 should be replied by RNR with f=1 (8.4.7) */
switch (frame[1] & 0x0C)
{
case LAPM_S_RR:
s->far_busy = false;
ack_info(ss, frame[2] >> 1);
/* If p = 1 may be used for status checking? */
tx_information_rr_rnr_response(ss, frame, len);
break;
case LAPM_S_RNR:
s->far_busy = true;
ack_info(ss, frame[2] >> 1);
/* If p = 1 may be used for status checking? */
if ((frame[2] & 0x1))
tx_supervisory_frame(s, s->rsp_addr, (s->local_busy) ? LAPM_S_RNR : LAPM_S_RR, 1);
break;
case LAPM_S_REJ:
s->far_busy = false;
ack_info(ss, frame[2] >> 1);
if (s->retry_count == 0)
{
t401_stop_t403_start(ss);
reject_info(s);
}
tx_information_rr_rnr_response(ss, frame, len);
break;
case LAPM_S_SREJ:
/* TODO: */
return;
default:
return;
}
}
/*- End of function --------------------------------------------------------*/
static void rx_supervisory_rsp_frame(v42_state_t *ss, const uint8_t *frame, int len)
{
lapm_state_t *s;
s = &ss->lapm;
if (s->retry_count == 0 && (frame[2] & 0x1))
return;
/* Ack I frames <= NR - 1 */
switch (frame[1] & 0x0C)
{
case LAPM_S_RR:
s->far_busy = false;
ack_info(ss, frame[2] >> 1);
if (s->retry_count && (frame[2] & 0x1))
{
reject_info(s);
t401_stop_t403_start(ss);
}
break;
case LAPM_S_RNR:
s->far_busy = true;
ack_info(ss, frame[2] >> 1);
if (s->retry_count && (frame[2] & 0x1))
{
reject_info(s);
t401_stop_t403_start(ss);
}
if (s->retry_count == 0)
t401_start(ss);
break;
case LAPM_S_REJ:
s->far_busy = false;
ack_info(ss, frame[2] >> 1);
if (s->retry_count == 0 || (frame[2] & 0x1))
{
reject_info(s);
t401_stop_t403_start(ss);
}
break;
case LAPM_S_SREJ:
/* TODO: */
return;
default:
return;
}
}
/*- End of function --------------------------------------------------------*/
static int rx_unnumbered_cmd_frame(v42_state_t *ss, const uint8_t *frame, int len)
{
lapm_state_t *s;
s = &ss->lapm;
switch (frame[1] & 0xEC)
{
case LAPM_U_SABME:
/* Discard un-acked I frames. Reset vs, vr, and va. Clear exceptions */
reset_lapm(ss);
/* Going to connected state */
s->state = LAPM_DATA;
/* Respond UA (or DM on error) */
// fixme: why may be error and LAPM_U_DM ??
tx_unnumbered_frame(s, s->rsp_addr, LAPM_U_UA | (frame[1] & 0x10), NULL, 0);
t401_stop_t403_start(ss);
report_rx_status_change(ss, SIG_STATUS_LINK_CONNECTED);
break;
case LAPM_U_UI:
/* Break signal */
/* TODO: */
break;
case LAPM_U_DISC:
/* Respond UA (or DM) */
if (s->state == LAPM_IDLE)
{
tx_unnumbered_frame(s, s->rsp_addr, LAPM_U_DM | LAPM_U_PF, NULL, 0);
}
else
{
/* Going to disconnected state, discard unacked I frames, reset all. */
s->state = LAPM_IDLE;
reset_lapm(ss);
tx_unnumbered_frame(s, s->rsp_addr, LAPM_U_UA | (frame[1] & 0x10), NULL, 0);
t401_stop(ss);
/* TODO: notify CF */
report_rx_status_change(ss, SIG_STATUS_LINK_DISCONNECTED);
}
break;
case LAPM_U_XID:
/* Exchange general ID info */
receive_xid(ss, frame, len);
transmit_xid(ss, s->rsp_addr);
break;
case LAPM_U_TEST:
/* TODO: */
break;
default:
return -1;
}
return 0;
}
/*- End of function --------------------------------------------------------*/
static int rx_unnumbered_rsp_frame(v42_state_t *ss, const uint8_t *frame, int len)
{
lapm_state_t *s;
s = &ss->lapm;
switch (frame[1] & 0xEC)
{
case LAPM_U_DM:
switch (s->state)
{
case LAPM_IDLE:
if (!(frame[1] & 0x10))
{
/* TODO: notify CF */
report_rx_status_change(ss, SIG_STATUS_LINK_CONNECTED);
}
break;
case LAPM_ESTABLISH:
case LAPM_RELEASE:
if ((frame[1] & 0x10))
{
s->state = LAPM_IDLE;
reset_lapm(ss);
t401_stop(ss);
/* TODO: notify CF */
report_rx_status_change(ss, SIG_STATUS_LINK_DISCONNECTED);
}
break;
case LAPM_DATA:
if (s->retry_count || !(frame[1] & 0x10))
{
s->state = LAPM_IDLE;
reset_lapm(ss);
/* TODO: notify CF */
report_rx_status_change(ss, SIG_STATUS_LINK_DISCONNECTED);
}
break;
default:
break;
}
break;
case LAPM_U_UI:
/* TODO: */
break;
case LAPM_U_UA:
switch (s->state)
{
case LAPM_ESTABLISH:
s->state = LAPM_DATA;
reset_lapm(ss);
t401_stop_t403_start(ss);
report_rx_status_change(ss, SIG_STATUS_LINK_CONNECTED);
break;
case LAPM_RELEASE:
s->state = LAPM_IDLE;
reset_lapm(ss);
t401_stop(ss);
report_rx_status_change(ss, SIG_STATUS_LINK_DISCONNECTED);
break;
default:
/* Unsolicited UA */
/* TODO: */
break;
}
/* Clear all exceptions, busy states (self and peer) */
/* Reset vars */
break;
case LAPM_U_FRMR:
/* Non-recoverable error */
/* TODO: */
break;
case LAPM_U_XID:
if (s->configuring)
{
receive_xid(ss, frame, len);
s->configuring = false;
t401_stop(ss);
switch (s->state)
{
case LAPM_IDLE:
lapm_connect(ss);
break;
case LAPM_DATA:
s->local_busy = false;
tx_supervisory_frame(s, s->cmd_addr, LAPM_S_RR, 0);
break;
}
}
break;
default:
break;
}
return 0;
}
/*- End of function --------------------------------------------------------*/
static void lapm_hdlc_underflow(void *user_data)
{
lapm_state_t *s;
v42_state_t *ss;
v42_frame_t *f;
ss = (v42_state_t *) user_data;
s = &ss->lapm;
if (s->ctrl_get != s->ctrl_put)
{
/* Send control frame */
f = &s->ctrl_buf[s->ctrl_get];
if (++s->ctrl_get >= V42_CTRL_FRAMES)
s->ctrl_get = 0;
}
else
{
if (s->far_busy || s->configuring || s->state != LAPM_DATA)
{
hdlc_tx_flags(&s->hdlc_tx, 10);
return;
}
if (s->info_get == s->info_put && !tx_information_frame(ss))
{
hdlc_tx_flags(&s->hdlc_tx, 10);
return;
}
/* Send info frame */
f = &s->info_buf[s->info_get];
if (++s->info_get >= V42_INFO_FRAMES)
s->info_get = 0;
f->buf[0] = s->cmd_addr;
f->buf[1] = s->vs << 1;
f->buf[2] = s->vr << 1;
s->vs = (s->vs + 1) & 0x7F;
if (ss->bit_timer == 0)
t401_start(ss);
}
hdlc_tx_frame(&s->hdlc_tx, f->buf, f->len);
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE(void) lapm_receive(void *user_data, const uint8_t *frame, int len, int ok)
{
lapm_state_t *s;
v42_state_t *ss;
ss = (v42_state_t *) user_data;
s = &ss->lapm;
if (len < 0)
{
span_log(&ss->logging, SPAN_LOG_DEBUG, "V.42 rx status is %s (%d)\n", signal_status_to_str(len), len);
return;
}
if (!ok)
return;
switch ((frame[1] & LAPM_FRAMETYPE_MASK))
{
case LAPM_FRAMETYPE_I:
case LAPM_FRAMETYPE_I_ALT:
receive_information_frame(ss, frame, len);
break;
case LAPM_FRAMETYPE_S:
if (!valid_data_state(ss))
return;
if (frame[0] == s->rsp_addr)
rx_supervisory_cmd_frame(ss, frame, len);
else
rx_supervisory_rsp_frame(ss, frame, len);
break;
case LAPM_FRAMETYPE_U:
if (frame[0] == s->rsp_addr)
rx_unnumbered_cmd_frame(ss, frame, len);
else
rx_unnumbered_rsp_frame(ss, frame, len);
break;
}
}
/*- End of function --------------------------------------------------------*/
static int lapm_connect(v42_state_t *ss)
{
lapm_state_t *s;
s = &ss->lapm;
if (s->state != LAPM_IDLE)
return -1;
/* Negotiate params */
//transmit_xid(s, s->cmd_addr);
reset_lapm(ss);
/* Connect */
s->state = LAPM_ESTABLISH;
tx_unnumbered_frame(s, s->cmd_addr, LAPM_U_SABME | LAPM_U_PF, NULL, 0);
/* Start T401 (and not T403) */
t401_start(ss);
return 0;
}
/*- End of function --------------------------------------------------------*/
static int lapm_disconnect(v42_state_t *ss)
{
lapm_state_t *s;
s = &ss->lapm;
s->state = LAPM_RELEASE;
tx_unnumbered_frame(s, s->cmd_addr, LAPM_U_DISC | LAPM_U_PF, NULL, 0);
t401_start(ss);
return 0;
}
/*- End of function --------------------------------------------------------*/
static int lapm_config(v42_state_t *ss)
{
lapm_state_t *s;
s = &ss->lapm;
s->configuring = true;
if (s->state == LAPM_DATA)
{
s->local_busy = true;
tx_supervisory_frame(s, s->cmd_addr, LAPM_S_RNR, 1);
}
transmit_xid(ss, s->cmd_addr);
t401_start(ss);
return 0;
}
/*- End of function --------------------------------------------------------*/
static void reset_lapm(v42_state_t *ss)
{
lapm_state_t *s;
s = &ss->lapm;
/* Reset the LAP.M state */
s->local_busy = false;
s->far_busy = false;
s->vs = 0;
s->va = 0;
s->vr = 0;
/* Discard any info frames still queued for transmission */
s->info_put = 0;
s->info_acked = 0;
s->info_get = 0;
/* Discard any control frames */
s->ctrl_put = 0;
s->ctrl_get = 0;
s->tx_window_size_k = ss->config.v42_tx_window_size_k;
s->rx_window_size_k = ss->config.v42_rx_window_size_k;
s->tx_n401 = ss->config.v42_tx_n401;
s->rx_n401 = ss->config.v42_rx_n401;
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE(void) v42_stop(v42_state_t *ss)
{
lapm_state_t *s;
s = &ss->lapm;
ss->bit_timer = 0;
s->packer_process = NULL;
lapm_disconnect(ss);
}
/*- End of function --------------------------------------------------------*/
static void restart_lapm(v42_state_t *s)
{
if (s->calling_party)
{
s->bit_timer = 48*8;
s->bit_timer_func = initiate_negotiation_expired;
}
else
{
lapm_hdlc_underflow(s);
}
s->lapm.packer_process = NULL;
s->lapm.state = LAPM_IDLE;
}
/*- End of function --------------------------------------------------------*/
static void negotiation_rx_bit(v42_state_t *s, int new_bit)
{
/* DC1 with even parity, 8-16 ones, DC1 with odd parity, 8-16 ones */
/* uint8_t odp = "0100010001 11111111 0100010011 11111111"; */
/* V.42 OK E , 8-16 ones, C, 8-16 ones */
/* uint8_t adp_v42 = "0101000101 11111111 0110000101 11111111"; */
/* V.42 disabled E, 8-16 ones, NULL, 8-16 ones */
/* uint8_t adp_nov42 = "0101000101 11111111 0000000001 11111111"; */
/* There may be no negotiation, so we need to process this data through the
HDLC receiver as well */
if (new_bit < 0)
{
/* Special conditions */
span_log(&s->logging, SPAN_LOG_DEBUG, "V.42 rx status is %s (%d)\n", signal_status_to_str(new_bit), new_bit);
return;
}
/*endif*/
new_bit &= 1;
s->neg.rxstream = (s->neg.rxstream << 1) | new_bit;
switch (s->neg.rx_negotiation_step)
{
case 0:
/* Look for some ones */
if (new_bit)
break;
/*endif*/
s->neg.rx_negotiation_step = 1;
s->neg.rxbits = 0;
s->neg.rxstream = ~1;
s->neg.rxoks = 0;
break;
case 1:
/* Look for the first character */
if (++s->neg.rxbits < 9)
break;
/*endif*/
s->neg.rxstream &= 0x3FF;
if (s->calling_party && s->neg.rxstream == 0x145)
{
s->neg.rx_negotiation_step++;
}
else if (!s->calling_party && s->neg.rxstream == 0x111)
{
s->neg.rx_negotiation_step++;
}
else
{
s->neg.rx_negotiation_step = 0;
}
/*endif*/
s->neg.rxbits = 0;
s->neg.rxstream = ~0;
break;
case 2:
/* Look for 8 to 16 ones */
s->neg.rxbits++;
if (new_bit)
break;
/*endif*/
if (s->neg.rxbits >= 8 && s->neg.rxbits <= 16)
s->neg.rx_negotiation_step++;
else
s->neg.rx_negotiation_step = 0;
/*endif*/
s->neg.rxbits = 0;
s->neg.rxstream = ~1;
break;
case 3:
/* Look for the second character */
if (++s->neg.rxbits < 9)
break;
/*endif*/
s->neg.rxstream &= 0x3FF;
if (s->calling_party && s->neg.rxstream == 0x185)
{
s->neg.rx_negotiation_step++;
}
else if (s->calling_party && s->neg.rxstream == 0x001)
{
s->neg.rx_negotiation_step++;
}
else if (!s->calling_party && s->neg.rxstream == 0x113)
{
s->neg.rx_negotiation_step++;
}
else
{
s->neg.rx_negotiation_step = 0;
}
/*endif*/
s->neg.rxbits = 0;
s->neg.rxstream = ~0;
break;
case 4:
/* Look for 8 to 16 ones */
s->neg.rxbits++;
if (new_bit)
break;
/*endif*/
if (s->neg.rxbits >= 8 && s->neg.rxbits <= 16)
{
if (++s->neg.rxoks >= 2)
{
/* HIT - we have found the "V.42 supported" pattern. */
s->neg.rx_negotiation_step++;
if (s->calling_party)
{
t400_stop(s);
s->lapm.state = LAPM_IDLE;
report_rx_status_change(s, s->lapm.state);
restart_lapm(s);
}
else
{
s->neg.odp_seen = true;
}
/*endif*/
break;
}
/*endif*/
s->neg.rx_negotiation_step = 1;
s->neg.rxbits = 0;
s->neg.rxstream = ~1;
}
else
{
s->neg.rx_negotiation_step = 0;
s->neg.rxbits = 0;
s->neg.rxstream = ~0;
}
/*endif*/
break;
case 5:
/* Parked */
break;
}
/*endswitch*/
}
/*- End of function --------------------------------------------------------*/
static int v42_support_negotiation_tx_bit(v42_state_t *s)
{
int bit;
if (s->calling_party)
{
if (s->neg.txbits <= 0)
{
s->neg.txstream = 0x3FE22;
s->neg.txbits = 36;
}
else if (s->neg.txbits == 18)
{
s->neg.txstream = 0x3FF22;
}
/*endif*/
bit = s->neg.txstream & 1;
s->neg.txstream >>= 1;
s->neg.txbits--;
}
else
{
if (s->neg.odp_seen && s->neg.txadps < 10)
{
if (s->neg.txbits <= 0)
{
if (++s->neg.txadps >= 10)
{
t400_stop(s);
s->lapm.state = LAPM_IDLE;
report_rx_status_change(s, s->lapm.state);
s->neg.txstream = 1;
restart_lapm(s);
}
else
{
s->neg.txstream = 0x3FE8A;
s->neg.txbits = 36;
}
/*endif*/
}
else if (s->neg.txbits == 18)
{
s->neg.txstream = 0x3FE86;
}
/*endif*/
bit = s->neg.txstream & 1;
s->neg.txstream >>= 1;
s->neg.txbits--;
}
else
{
bit = 1;
}
/*endif*/
}
/*endif*/
return bit;
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE(void) v42_rx_bit(void *user_data, int bit)
{
v42_state_t *s;
s = (v42_state_t *) user_data;
if (s->lapm.state == LAPM_DETECT)
negotiation_rx_bit(s, bit);
else
hdlc_rx_put_bit(&s->lapm.hdlc_rx, bit);
/*endif*/
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE(int) v42_tx_bit(void *user_data)
{
v42_state_t *s;
int bit;
s = (v42_state_t *) user_data;
if (s->bit_timer && (--s->bit_timer) <= 0)
{
s->bit_timer = 0;
s->bit_timer_func(s);
}
if (s->lapm.state == LAPM_DETECT)
bit = v42_support_negotiation_tx_bit(s);
else
bit = hdlc_tx_get_bit(&s->lapm.hdlc_tx);
/*endif*/
return bit;
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE(int) v42_set_local_busy_status(v42_state_t *s, int busy)
{
int previous_busy;
previous_busy = s->lapm.local_busy;
s->lapm.local_busy = busy;
return previous_busy;
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE(int) v42_get_far_busy_status(v42_state_t *s)
{
return s->lapm.far_busy;
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE(logging_state_t *) v42_get_logging_state(v42_state_t *s)
{
return &s->logging;
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE(void) v42_set_status_callback(v42_state_t *s, modem_status_func_t status_handler, void *user_data)
{
s->lapm.status_handler = status_handler;
s->lapm.status_user_data = user_data;
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE(void) v42_restart(v42_state_t *s)
{
hdlc_tx_init(&s->lapm.hdlc_tx, false, 1, true, lapm_hdlc_underflow, s);
hdlc_rx_init(&s->lapm.hdlc_rx, false, false, 1, lapm_receive, s);
if (s->detect)
{
/* We need to do the V.42 support detection sequence */
s->neg.txstream = ~0;
s->neg.txbits = 0;
s->neg.rxstream = ~0;
s->neg.rxbits = 0;
s->neg.rxoks = 0;
s->neg.txadps = 0;
s->neg.rx_negotiation_step = 0;
s->neg.odp_seen = false;
t400_start(s);
s->lapm.state = LAPM_DETECT;
}
else
{
/* Go directly to LAP.M mode */
s->lapm.state = LAPM_IDLE;
restart_lapm(s);
}
/*endif*/
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE(v42_state_t *) v42_init(v42_state_t *ss,
bool calling_party,
bool detect,
get_msg_func_t iframe_get,
put_msg_func_t iframe_put,
void *user_data)
{
lapm_state_t *s;
if (ss == NULL)
{
if ((ss = (v42_state_t *) span_alloc(sizeof(*ss))) == NULL)
return NULL;
}
memset(ss, 0, sizeof(*ss));
s = &ss->lapm;
ss->calling_party = calling_party;
ss->detect = detect;
s->iframe_get = iframe_get;
s->iframe_get_user_data = user_data;
s->iframe_put = iframe_put;
s->iframe_put_user_data = user_data;
s->state = (ss->detect) ? LAPM_DETECT : LAPM_IDLE;
s->local_busy = false;
s->far_busy = false;
/* The address octet is:
Data link connection identifier (0)
Command/response (0 if answerer, 1 if originator)
Extended address (1) */
s->cmd_addr = (LAPM_DLCI_DTE_TO_DTE << 2) | ((ss->calling_party) ? 0x02 : 0x00) | 0x01;
s->rsp_addr = (LAPM_DLCI_DTE_TO_DTE << 2) | ((ss->calling_party) ? 0x00 : 0x02) | 0x01;
/* Set default values for the LAP.M parameters. These can be modified later. */
ss->config.v42_tx_window_size_k = V42_DEFAULT_WINDOW_SIZE_K;
ss->config.v42_rx_window_size_k = V42_DEFAULT_WINDOW_SIZE_K;
ss->config.v42_tx_n401 = V42_DEFAULT_N_401;
ss->config.v42_rx_n401 = V42_DEFAULT_N_401;
/* TODO: This should be part of the V.42bis startup */
ss->config.comp = 1;
ss->config.comp_dict_size = 512;
ss->config.comp_max_string = 6;
ss->tx_bit_rate = 28800;
reset_lapm(ss);
span_log_init(&ss->logging, SPAN_LOG_NONE, NULL);
span_log_set_protocol(&ss->logging, "V.42");
return ss;
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE(int) v42_release(v42_state_t *s)
{
reset_lapm(s);
return 0;
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE(int) v42_free(v42_state_t *s)
{
v42_release(s);
span_free(s);
return 0;
}
/*- End of function --------------------------------------------------------*/
/*- End of file ------------------------------------------------------------*/