394 lines
9.3 KiB
C
394 lines
9.3 KiB
C
/*
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* ----------------------------------------------------------------------------
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* "THE BEER-WARE LICENSE" (Revision 42):
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* <phk@FreeBSD.org> wrote this file. As long as you retain this notice you
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* can do whatever you want with this stuff. If we meet some day, and you think
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* this stuff is worth it, you can buy me a beer in return. Poul-Henning Kamp
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* ----------------------------------------------------------------------------
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*
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* This is a V.21 modem for ISDN4BSD.
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*
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* $FreeBSD$
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*/
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#include <string.h>
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#include <stdio.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <fcntl.h>
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#include <err.h>
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#include <sys/ioccom.h>
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#include <errno.h>
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#include <syslog.h>
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#include <sys/types.h>
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#include <sys/ioctl.h>
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#include <termios.h>
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#include <libutil.h>
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#include <machine/i4b_tel_ioctl.h>
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static void create_session(void);
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static void input_byte(int byte, int stopbit);
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static void sample(int vol, int* tones);
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static void tonedetect(unsigned char *ptr, int count);
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static void uart(int bit);
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static int dcd; /* Carrier on ? */
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static int ptyfd = -1; /* PTY filedescriptor */
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static int telfd = -1; /* I4BTEL filedescriptor */
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/*
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* Alaw to Linear [-32767..32767] conversion
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*/
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static int a2l[256] = { -5504, -5248, -6016, -5760, -4480, -4224,
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-4992, -4736, -7552, -7296, -8064, -7808, -6528, -6272, -7040,
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-6784, -2752, -2624, -3008, -2880, -2240, -2112, -2496, -2368,
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-3776, -3648, -4032, -3904, -3264, -3136, -3520, -3392, -22016,
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-20992, -24064, -23040, -17920, -16896, -19968, -18944, -30208,
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-29184, -32256, -31232, -26112, -25088, -28160, -27136, -11008,
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-10496, -12032, -11520, -8960, -8448, -9984, -9472, -15104, -14592,
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-16128, -15616, -13056, -12544, -14080, -13568, -344, -328, -376,
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-360, -280, -264, -312, -296, -472, -456, -504, -488, -408, -392,
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-440, -424, -88, -72, -120, -104, -24, -8, -56, -40, -216, -200,
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-248, -232, -152, -136, -184, -168, -1376, -1312, -1504, -1440,
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-1120, -1056, -1248, -1184, -1888, -1824, -2016, -1952, -1632,
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-1568, -1760, -1696, -688, -656, -752, -720, -560, -528, -624,
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-592, -944, -912, -1008, -976, -816, -784, -880, -848, 5504, 5248,
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6016, 5760, 4480, 4224, 4992, 4736, 7552, 7296, 8064, 7808, 6528,
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6272, 7040, 6784, 2752, 2624, 3008, 2880, 2240, 2112, 2496, 2368,
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3776, 3648, 4032, 3904, 3264, 3136, 3520, 3392, 22016, 20992, 24064,
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23040, 17920, 16896, 19968, 18944, 30208, 29184, 32256, 31232,
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26112, 25088, 28160, 27136, 11008, 10496, 12032, 11520, 8960, 8448,
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9984, 9472, 15104, 14592, 16128, 15616, 13056, 12544, 14080, 13568,
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344, 328, 376, 360, 280, 264, 312, 296, 472, 456, 504, 488, 408,
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392, 440, 424, 88, 72, 120, 104, 24, 8, 56, 40, 216, 200, 248, 232,
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152, 136, 184, 168, 1376, 1312, 1504, 1440, 1120, 1056, 1248, 1184,
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1888, 1824, 2016, 1952, 1632, 1568, 1760, 1696, 688, 656, 752, 720,
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560, 528, 624, 592, 944, 912, 1008, 976, 816, 784, 880, 848 };
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/*
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* A High Q Tone detector
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*/
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#define NTONES 2 /* Number of tones to detect */
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#define SCALE 4096 /* Scaling factor */
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#define EXPAVG 14 /* Exponential Average factor */
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#define POLERAD 3885 /* pole_radius ^ 2 * SCALE */
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/* Table of "-cos(2 * PI * frequency / sample_rate) * SCALE" */
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static int p[NTONES] = {
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-2941, /* 980 Hz */
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-2460 /* 1180 Hz */
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};
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static void
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tonedetect(unsigned char *ptr, int count)
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{
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int i, j;
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int y;
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int c, d, f, n;
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static int k[NTONES], h[NTONES];
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static int tones[NTONES];
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static int amplitude;
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for (i = 0; i < count; i++) {
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y = a2l[*ptr++];
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if (y > 0)
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amplitude += (y - amplitude) / EXPAVG;
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else
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amplitude += (-y - amplitude) / EXPAVG;
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for(j = 0; j < NTONES; j++) {
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c = (POLERAD * (y - k[j])) / SCALE;
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d = y + c;
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f = (p[j] * (d - h[j])) / SCALE;
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n = y - k[j] - c;
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if (n < 0)
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n = -n;
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k[j] = h[j] + f;
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h[j] = f + d;
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tones[j] += (n - tones[j]) / EXPAVG;
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}
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sample(amplitude, tones);
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}
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}
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/*
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* Taste each sample, detect (loss off) carrier, and feed uart
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*/
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#define NCARRIER 1000 /* Samples of carrier for detection */
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static void
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sample(int vol, int* tones)
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{
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static int carrier;
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if ((tones[0] + tones[1]) > vol * 3/2) { /* XXX */
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if (carrier < NCARRIER)
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carrier ++;
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} else {
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if (carrier > 0)
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carrier --;
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}
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if (!dcd && carrier > NCARRIER / 2) {
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syslog(LOG_ERR, "CARRIER ON");
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dcd = 1;
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} else if (dcd && carrier < NCARRIER / 2) {
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syslog(LOG_ERR, "CARRIER OFF");
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dcd = 0;
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}
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if (!dcd)
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return;
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if (tones[0] > tones[1]) {
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uart(1);
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} else {
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uart(0);
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}
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}
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/*
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* A UART in software
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*/
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#define BITCENTER 13 /* Middle of a bit: 8000/300/2 */
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static int bitsample[] = { /* table of sampling points */
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BITCENTER,
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BITCENTER + 27,
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BITCENTER + 54,
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BITCENTER + 80,
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BITCENTER + 107,
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BITCENTER + 134,
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BITCENTER + 160,
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BITCENTER + 187,
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BITCENTER + 214,
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BITCENTER + 240
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};
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static void
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uart(int bit)
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{
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static int n, v, j;
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if (n == 0 && bit == 1)
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return; /* Waiting for start bit */
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if (n == 0) {
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j = 0; /* Begin start bit */
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v = 0;
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n++;
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} else if (j == 0 && bit && n > bitsample[j]) {
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n = 0; /* Gone by middle of start bit */
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} else if (n > bitsample[j]) {
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j++; /* Sample point */
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if (j == 10) {
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n = 0;
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input_byte(v, bit);
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} else {
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v = v / 2 + 128 * bit;
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n++;
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}
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} else {
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n++;
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}
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}
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/*
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* Send a byte using kenrnel tone generation support
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*/
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static void
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output_byte(int val)
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{
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struct i4b_tel_tones tt;
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int i;
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i = 0;
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tt.frequency[i] = 1850; tt.duration[i++] = 27;
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tt.frequency[i] = val & 1 ? 1650 : 1850; tt.duration[i++] = 27;
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tt.frequency[i] = val & 2 ? 1650 : 1850; tt.duration[i++] = 26;
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tt.frequency[i] = val & 4 ? 1650 : 1850; tt.duration[i++] = 27;
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tt.frequency[i] = val & 8 ? 1650 : 1850; tt.duration[i++] = 27;
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tt.frequency[i] = val & 16 ? 1650 : 1850; tt.duration[i++] = 26;
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tt.frequency[i] = val & 32 ? 1650 : 1850; tt.duration[i++] = 27;
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tt.frequency[i] = val & 64 ? 1650 : 1850; tt.duration[i++] = 27;
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tt.frequency[i] = val & 128 ? 1650 : 1850; tt.duration[i++] = 26;
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tt.frequency[i] = 1650; tt.duration[i++] = 27;
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tt.frequency[i] = 1650; tt.duration[i++] = 0;
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i = ioctl(telfd, I4B_TEL_TONES, &tt);
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if (i != 0 && errno != EAGAIN) {
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syslog(LOG_ERR, "%d: *** %d/%d ***", __LINE__, i, errno);
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exit(0);
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}
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}
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/*
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* Create Session
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*/
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static void
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create_session(void)
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{
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int i;
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char buf[100];
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i = forkpty(&ptyfd, buf, 0, 0);
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if (i == 0) {
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execl("/usr/libexec/getty", "getty", "std.300", "-", NULL);
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syslog(LOG_ERR, "exec getty %d", errno);
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exit(2);
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} else if (i < 0) {
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syslog(LOG_ERR, "forkpty failed %d", errno);
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exit(2);
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}
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syslog(LOG_ERR, "pty %s", buf);
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}
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static void
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input_byte(int byte, int stopbit)
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{
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u_char c;
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int i;
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static int first;
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static u_char buf[80];
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if (!stopbit)
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return;
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c = byte;
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/*
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* I have no idea why, but my TB2500 modem sends a sequence of
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* 28 bytes after carrier is established at the link level, but
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* before it is acceptted at the logical level.
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*
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* [16100214010201060100000000ff0201020301080402400010034510]
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*
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* Unfortunately this contains a ^D which kills getty.
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* The following code swallows this sequence, assuming that it
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* is always the same length and always start with 0x16.
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*
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*/
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if (first == 0 && c == 0x16) {
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sprintf(buf, "%02x", c);
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first = 27;
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return;
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} else if (first == 0) {
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first = -1;
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dcd = 2;
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return;
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}
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if (first > 0) {
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sprintf(buf + strlen(buf), "%02x", c);
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first--;
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if (!first) {
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syslog(LOG_NOTICE, "Got magic [%s]", buf);
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*buf = 0;
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}
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return;
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}
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if (ptyfd != -1 && dcd) {
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i = write(ptyfd, &c, 1);
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if (i != 1 && errno != EAGAIN) {
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syslog(LOG_ERR, "%d: *** %d/%d ***", __LINE__, i, errno);
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exit(0);
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}
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}
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}
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int
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main(int argc, char **argv)
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{
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char *device = "/dev/tel0";
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u_char ibuf[2048];
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int ii, io;
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int i, maxfd;
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struct i4b_tel_tones tt;
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fd_set rfd, wfd, efd;
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openlog("v21modem", LOG_PID, LOG_DAEMON);
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/* Find our device name */
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for (i = 0; i < argc; i++)
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if (!strcmp(argv[i], "-D"))
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device = argv[i + 1];
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telfd = open(device, O_RDWR, 0);
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if (telfd < 0) {
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syslog(LOG_ERR, "open %s: %m", device);
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exit (0);
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}
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syslog(LOG_NOTICE, "Running on %s", device);
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/* Output V.25 tone and carrier */
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i = 0;
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tt.frequency[i] = 0; tt.duration[i++] = 1000;
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tt.frequency[i] = 2100; tt.duration[i++] = 2*8000;
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tt.frequency[i] = 0; tt.duration[i++] = 400;
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tt.frequency[i] = 1650; tt.duration[i++] = 1;
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tt.frequency[i] = 1650; tt.duration[i++] = 0;
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tt.frequency[i] = 0; tt.duration[i++] = 0;
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i = ioctl(telfd, I4B_TEL_TONES, &tt);
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if (i < 0) {
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syslog(LOG_ERR, "hangup");
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exit(0);
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}
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create_session();
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/* Wait for carrier */
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do {
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ii = read(telfd, ibuf, sizeof ibuf);
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tonedetect(ibuf, ii);
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} while (ii > 0 && dcd != 2);
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if (ii < 0) {
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syslog(LOG_ERR, "hangup");
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exit(0);
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}
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maxfd = ptyfd;
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if (telfd > maxfd)
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maxfd = telfd;
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maxfd += 1;
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do {
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FD_ZERO(&rfd);
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FD_SET(telfd, &rfd);
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FD_SET(ptyfd, &rfd);
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FD_ZERO(&wfd);
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FD_ZERO(&efd);
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FD_SET(telfd, &efd);
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FD_SET(ptyfd, &efd);
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i = select(maxfd, &rfd, &wfd, &efd, NULL);
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if (FD_ISSET(telfd, &rfd)) {
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ii = read(telfd, ibuf, sizeof ibuf);
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if (ii > 0)
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tonedetect(ibuf, ii);
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else
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syslog(LOG_ERR, "hangup");
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}
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if (FD_ISSET(ptyfd, &rfd)) {
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io = read(ptyfd, ibuf, 1);
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if (io == 1)
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output_byte(*ibuf);
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else if (io == 0) {
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syslog(LOG_ERR, "Session EOF");
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exit(0);
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}
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}
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if (FD_ISSET(telfd, &efd)) {
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syslog(LOG_ERR, "Exception TELFD");
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exit (0);
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}
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if (FD_ISSET(ptyfd, &efd)) {
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syslog(LOG_ERR, "Exception PTYFD");
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exit (0);
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}
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} while (dcd);
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syslog(LOG_ERR, "Carrier Lost");
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exit(0);
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}
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