/* * ---------------------------------------------------------------------------- * "THE BEER-WARE LICENSE" (Revision 42): * wrote this file. As long as you retain this notice you * can do whatever you want with this stuff. If we meet some day, and you think * this stuff is worth it, you can buy me a beer in return. Poul-Henning Kamp * ---------------------------------------------------------------------------- * * This is a V.21 modem for ISDN4BSD. * * $FreeBSD: src/share/examples/isdn/v21/v21modem.c,v 1.2 2001/07/09 09:23:44 brian Exp $ */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include static void create_session(void); static void input_byte(int byte, int stopbit); static void sample(int vol, int* tones); static void tonedetect(unsigned char *ptr, int count); static void uart(int bit); static int dcd; /* Carrier on ? */ static int ptyfd = -1; /* PTY filedescriptor */ static int telfd = -1; /* I4BTEL filedescriptor */ /* * Alaw to Linear [-32767..32767] conversion */ static int a2l[256] = { -5504, -5248, -6016, -5760, -4480, -4224, -4992, -4736, -7552, -7296, -8064, -7808, -6528, -6272, -7040, -6784, -2752, -2624, -3008, -2880, -2240, -2112, -2496, -2368, -3776, -3648, -4032, -3904, -3264, -3136, -3520, -3392, -22016, -20992, -24064, -23040, -17920, -16896, -19968, -18944, -30208, -29184, -32256, -31232, -26112, -25088, -28160, -27136, -11008, -10496, -12032, -11520, -8960, -8448, -9984, -9472, -15104, -14592, -16128, -15616, -13056, -12544, -14080, -13568, -344, -328, -376, -360, -280, -264, -312, -296, -472, -456, -504, -488, -408, -392, -440, -424, -88, -72, -120, -104, -24, -8, -56, -40, -216, -200, -248, -232, -152, -136, -184, -168, -1376, -1312, -1504, -1440, -1120, -1056, -1248, -1184, -1888, -1824, -2016, -1952, -1632, -1568, -1760, -1696, -688, -656, -752, -720, -560, -528, -624, -592, -944, -912, -1008, -976, -816, -784, -880, -848, 5504, 5248, 6016, 5760, 4480, 4224, 4992, 4736, 7552, 7296, 8064, 7808, 6528, 6272, 7040, 6784, 2752, 2624, 3008, 2880, 2240, 2112, 2496, 2368, 3776, 3648, 4032, 3904, 3264, 3136, 3520, 3392, 22016, 20992, 24064, 23040, 17920, 16896, 19968, 18944, 30208, 29184, 32256, 31232, 26112, 25088, 28160, 27136, 11008, 10496, 12032, 11520, 8960, 8448, 9984, 9472, 15104, 14592, 16128, 15616, 13056, 12544, 14080, 13568, 344, 328, 376, 360, 280, 264, 312, 296, 472, 456, 504, 488, 408, 392, 440, 424, 88, 72, 120, 104, 24, 8, 56, 40, 216, 200, 248, 232, 152, 136, 184, 168, 1376, 1312, 1504, 1440, 1120, 1056, 1248, 1184, 1888, 1824, 2016, 1952, 1632, 1568, 1760, 1696, 688, 656, 752, 720, 560, 528, 624, 592, 944, 912, 1008, 976, 816, 784, 880, 848 }; /* * A High Q Tone detector */ #define NTONES 2 /* Number of tones to detect */ #define SCALE 4096 /* Scaling factor */ #define EXPAVG 14 /* Exponential Average factor */ #define POLERAD 3885 /* pole_radius ^ 2 * SCALE */ /* Table of "-cos(2 * PI * frequency / sample_rate) * SCALE" */ static int p[NTONES] = { -2941, /* 980 Hz */ -2460 /* 1180 Hz */ }; static void tonedetect(unsigned char *ptr, int count) { int i, j; int y; int c, d, f, n; static int k[NTONES], h[NTONES]; static int tones[NTONES]; static int amplitude; for (i = 0; i < count; i++) { y = a2l[*ptr++]; if (y > 0) amplitude += (y - amplitude) / EXPAVG; else amplitude += (-y - amplitude) / EXPAVG; for(j = 0; j < NTONES; j++) { c = (POLERAD * (y - k[j])) / SCALE; d = y + c; f = (p[j] * (d - h[j])) / SCALE; n = y - k[j] - c; if (n < 0) n = -n; k[j] = h[j] + f; h[j] = f + d; tones[j] += (n - tones[j]) / EXPAVG; } sample(amplitude, tones); } } /* * Taste each sample, detect (loss off) carrier, and feed uart */ #define NCARRIER 1000 /* Samples of carrier for detection */ static void sample(int vol, int* tones) { static int carrier; if ((tones[0] + tones[1]) > vol * 3/2) { /* XXX */ if (carrier < NCARRIER) carrier ++; } else { if (carrier > 0) carrier --; } if (!dcd && carrier > NCARRIER / 2) { syslog(LOG_ERR, "CARRIER ON"); dcd = 1; } else if (dcd && carrier < NCARRIER / 2) { syslog(LOG_ERR, "CARRIER OFF"); dcd = 0; } if (!dcd) return; if (tones[0] > tones[1]) { uart(1); } else { uart(0); } } /* * A UART in software */ #define BITCENTER 13 /* Middle of a bit: 8000/300/2 */ static int bitsample[] = { /* table of sampling points */ BITCENTER, BITCENTER + 27, BITCENTER + 54, BITCENTER + 80, BITCENTER + 107, BITCENTER + 134, BITCENTER + 160, BITCENTER + 187, BITCENTER + 214, BITCENTER + 240 }; static void uart(int bit) { static int n, v, j; if (n == 0 && bit == 1) return; /* Waiting for start bit */ if (n == 0) { j = 0; /* Begin start bit */ v = 0; n++; } else if (j == 0 && bit && n > bitsample[j]) { n = 0; /* Gone by middle of start bit */ } else if (n > bitsample[j]) { j++; /* Sample point */ if (j == 10) { n = 0; input_byte(v, bit); } else { v = v / 2 + 128 * bit; n++; } } else { n++; } } /* * Send a byte using kenrnel tone generation support */ static void output_byte(int val) { struct i4b_tel_tones tt; int i; i = 0; tt.frequency[i] = 1850; tt.duration[i++] = 27; tt.frequency[i] = val & 1 ? 1650 : 1850; tt.duration[i++] = 27; tt.frequency[i] = val & 2 ? 1650 : 1850; tt.duration[i++] = 26; tt.frequency[i] = val & 4 ? 1650 : 1850; tt.duration[i++] = 27; tt.frequency[i] = val & 8 ? 1650 : 1850; tt.duration[i++] = 27; tt.frequency[i] = val & 16 ? 1650 : 1850; tt.duration[i++] = 26; tt.frequency[i] = val & 32 ? 1650 : 1850; tt.duration[i++] = 27; tt.frequency[i] = val & 64 ? 1650 : 1850; tt.duration[i++] = 27; tt.frequency[i] = val & 128 ? 1650 : 1850; tt.duration[i++] = 26; tt.frequency[i] = 1650; tt.duration[i++] = 27; tt.frequency[i] = 1650; tt.duration[i++] = 0; i = ioctl(telfd, I4B_TEL_TONES, &tt); if (i != 0 && errno != EAGAIN) { syslog(LOG_ERR, "%d: *** %d/%d ***", __LINE__, i, errno); exit(0); } } /* * Create Session */ static void create_session(void) { int i; char buf[100]; i = forkpty(&ptyfd, buf, 0, 0); if (i == 0) { execl("/usr/libexec/getty", "getty", "std.300", "-", (char *)NULL); syslog(LOG_ERR, "exec getty %d", errno); exit(2); } else if (i < 0) { syslog(LOG_ERR, "forkpty failed %d", errno); exit(2); } syslog(LOG_ERR, "pty %s", buf); } static void input_byte(int byte, int stopbit) { u_char c; int i; static int first; static u_char buf[80]; if (!stopbit) return; c = byte; /* * I have no idea why, but my TB2500 modem sends a sequence of * 28 bytes after carrier is established at the link level, but * before it is acceptted at the logical level. * * [16100214010201060100000000ff0201020301080402400010034510] * * Unfortunately this contains a ^D which kills getty. * The following code swallows this sequence, assuming that it * is always the same length and always start with 0x16. * */ if (first == 0 && c == 0x16) { sprintf(buf, "%02x", c); first = 27; return; } else if (first == 0) { first = -1; dcd = 2; return; } if (first > 0) { sprintf(buf + strlen(buf), "%02x", c); first--; if (!first) { syslog(LOG_NOTICE, "Got magic [%s]", buf); *buf = 0; } return; } if (ptyfd != -1 && dcd) { i = write(ptyfd, &c, 1); if (i != 1 && errno != EAGAIN) { syslog(LOG_ERR, "%d: *** %d/%d ***", __LINE__, i, errno); exit(0); } } } int main(int argc, char **argv) { char *device = "/dev/tel0"; u_char ibuf[2048]; int ii, io; int i, maxfd; struct i4b_tel_tones tt; fd_set rfd, wfd, efd; openlog("v21modem", LOG_PID, LOG_DAEMON); /* Find our device name */ for (i = 0; i < argc; i++) if (!strcmp(argv[i], "-D")) device = argv[i + 1]; telfd = open(device, O_RDWR, 0); if (telfd < 0) { syslog(LOG_ERR, "open %s: %m", device); exit (0); } syslog(LOG_NOTICE, "Running on %s", device); /* Output V.25 tone and carrier */ i = 0; tt.frequency[i] = 0; tt.duration[i++] = 1000; tt.frequency[i] = 2100; tt.duration[i++] = 2*8000; tt.frequency[i] = 0; tt.duration[i++] = 400; tt.frequency[i] = 1650; tt.duration[i++] = 1; tt.frequency[i] = 1650; tt.duration[i++] = 0; tt.frequency[i] = 0; tt.duration[i++] = 0; i = ioctl(telfd, I4B_TEL_TONES, &tt); if (i < 0) { syslog(LOG_ERR, "hangup"); exit(0); } create_session(); /* Wait for carrier */ do { ii = read(telfd, ibuf, sizeof ibuf); tonedetect(ibuf, ii); } while (ii > 0 && dcd != 2); if (ii < 0) { syslog(LOG_ERR, "hangup"); exit(0); } maxfd = ptyfd; if (telfd > maxfd) maxfd = telfd; maxfd += 1; do { FD_ZERO(&rfd); FD_SET(telfd, &rfd); FD_SET(ptyfd, &rfd); FD_ZERO(&wfd); FD_ZERO(&efd); FD_SET(telfd, &efd); FD_SET(ptyfd, &efd); i = select(maxfd, &rfd, &wfd, &efd, NULL); if (FD_ISSET(telfd, &rfd)) { ii = read(telfd, ibuf, sizeof ibuf); if (ii > 0) tonedetect(ibuf, ii); else syslog(LOG_ERR, "hangup"); } if (FD_ISSET(ptyfd, &rfd)) { io = read(ptyfd, ibuf, 1); if (io == 1) output_byte(*ibuf); else if (io == 0) { syslog(LOG_ERR, "Session EOF"); exit(0); } } if (FD_ISSET(telfd, &efd)) { syslog(LOG_ERR, "Exception TELFD"); exit (0); } if (FD_ISSET(ptyfd, &efd)) { syslog(LOG_ERR, "Exception PTYFD"); exit (0); } } while (dcd); syslog(LOG_ERR, "Carrier Lost"); exit(0); }