miscutils/chat.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * bare bones chat utility
   4  * inspired by ppp's chat
   5  *
   6  * Copyright (C) 2008 by Vladimir Dronnikov <dronnikov@gmail.com>
   7  *
   8  * Licensed under GPLv2, see file LICENSE in this source tree.
   9  */
  10
  11 //usage:#define chat_trivial_usage
  12 //usage:       "EXPECT [SEND [EXPECT [SEND...]]]"
  13 //usage:#define chat_full_usage "\n\n"
  14 //usage:       "Useful for interacting with a modem connected to stdin/stdout.\n"
  15 //usage:       "A script consists of one or more \"expect-send\" pairs of strings,\n"
  16 //usage:       "each pair is a pair of arguments. Example:\n"
  17 //usage:       "chat '' ATZ OK ATD123456 CONNECT '' ogin: pppuser word: ppppass '~'"
  18
  19 #include "libbb.h"
  20
  21 // default timeout: 45 sec
  22 #define DEFAULT_CHAT_TIMEOUT 45*1000
  23 // max length of "abort string",
  24 // i.e. device reply which causes termination
  25 #define MAX_ABORT_LEN 50
  26
  27 // possible exit codes
  28 enum {
  29         ERR_OK = 0,     // all's well
  30         ERR_MEM,        // read too much while expecting
  31         ERR_IO,         // signalled or I/O error
  32         ERR_TIMEOUT,    // timed out while expecting
  33         ERR_ABORT,      // first abort condition was met
  34 //      ERR_ABORT2,     // second abort condition was met
  35 //      ...
  36 };
  37
  38 // exit code
  39 #define exitcode bb_got_signal
  40
  41 // trap for critical signals
  42 static void signal_handler(UNUSED_PARAM int signo)
  43 {
  44         // report I/O error condition
  45         exitcode = ERR_IO;
  46 }
  47
  48 #if !ENABLE_FEATURE_CHAT_IMPLICIT_CR
  49 #define unescape(s, nocr) unescape(s)
  50 #endif
  51 static size_t unescape(char *s, int *nocr)
  52 {
  53         char *start = s;
  54         char *p = s;
  55
  56         while (*s) {
  57                 char c = *s;
  58                 // do we need special processing?
  59                 // standard escapes + \s for space and \N for \0
  60                 // \c inhibits terminating \r for commands and is noop for expects
  61                 if ('\\' == c) {
  62                         c = *++s;
  63                         if (c) {
  64 #if ENABLE_FEATURE_CHAT_IMPLICIT_CR
  65                                 if ('c' == c) {
  66                                         *nocr = 1;
  67                                         goto next;
  68                                 }
  69 #endif
  70                                 if ('N' == c) {
  71                                         c = '\0';
  72                                 } else if ('s' == c) {
  73                                         c = ' ';
  74 #if ENABLE_FEATURE_CHAT_NOFAIL
  75                                 // unescape leading dash only
  76                                 // TODO: and only for expect, not command string
  77                                 } else if ('-' == c && (start + 1 == s)) {
  78                                         //c = '-';
  79 #endif
  80                                 } else {
  81                                         c = bb_process_escape_sequence((const char **)&s);
  82                                         s--;
  83                                 }
  84                         }
  85                 // ^A becomes \001, ^B -- \002 and so on...
  86                 } else if ('^' == c) {
  87                         c = *++s-'@';
  88                 }
  89                 // put unescaped char
  90                 *p++ = c;
  91 #if ENABLE_FEATURE_CHAT_IMPLICIT_CR
  92  next:
  93 #endif
  94                 // next char
  95                 s++;
  96         }
  97         *p = '\0';
  98
  99         return p - start;
 100 }
 101
 102 int chat_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 103 int chat_main(int argc UNUSED_PARAM, char **argv)
 104 {
 105         int record_fd = -1;
 106         bool echo = 0;
 107         // collection of device replies which cause unconditional termination
 108         llist_t *aborts = NULL;
 109         // inactivity period
 110         int timeout = DEFAULT_CHAT_TIMEOUT;
 111         // maximum length of abort string
 112 #if ENABLE_FEATURE_CHAT_VAR_ABORT_LEN
 113         size_t max_abort_len = 0;
 114 #else
 115 #define max_abort_len MAX_ABORT_LEN
 116 #endif
 117 #if ENABLE_FEATURE_CHAT_TTY_HIFI
 118         struct termios tio0, tio;
 119 #endif
 120         // directive names
 121         enum {
 122                 DIR_HANGUP = 0,
 123                 DIR_ABORT,
 124 #if ENABLE_FEATURE_CHAT_CLR_ABORT
 125                 DIR_CLR_ABORT,
 126 #endif
 127                 DIR_TIMEOUT,
 128                 DIR_ECHO,
 129                 DIR_SAY,
 130                 DIR_RECORD,
 131         };
 132
 133         // make x* functions fail with correct exitcode
 134         xfunc_error_retval = ERR_IO;
 135
 136         // trap vanilla signals to prevent process from being killed suddenly
 137         bb_signals(0
 138                 + (1 << SIGHUP)
 139                 + (1 << SIGINT)
 140                 + (1 << SIGTERM)
 141                 + (1 << SIGPIPE)
 142                 , signal_handler);
 143
 144 #if ENABLE_FEATURE_CHAT_TTY_HIFI
 145         tcgetattr(STDIN_FILENO, &tio);
 146         tio0 = tio;
 147         cfmakeraw(&tio);
 148         tcsetattr(STDIN_FILENO, TCSAFLUSH, &tio);
 149 #endif
 150
 151 #if ENABLE_FEATURE_CHAT_SWALLOW_OPTS
 152         getopt32(argv, "vVsSE");
 153         argv += optind;
 154 #else
 155         argv++; // goto first arg
 156 #endif
 157         // handle chat expect-send pairs
 158         while (*argv) {
 159                 // directive given? process it
 160                 int key = index_in_strings(
 161                         "HANGUP\0" "ABORT\0"
 162 #if ENABLE_FEATURE_CHAT_CLR_ABORT
 163                         "CLR_ABORT\0"
 164 #endif
 165                         "TIMEOUT\0" "ECHO\0" "SAY\0" "RECORD\0"
 166                         , *argv
 167                 );
 168                 if (key >= 0) {
 169                         // cache directive value
 170                         char *arg = *++argv;
 171                         // OFF -> 0, anything else -> 1
 172                         bool onoff = (0 != strcmp("OFF", arg));
 173                         // process directive
 174                         if (DIR_HANGUP == key) {
 175                                 // turn SIGHUP on/off
 176                                 signal(SIGHUP, onoff ? signal_handler : SIG_IGN);
 177                         } else if (DIR_ABORT == key) {
 178                                 // append the string to abort conditions
 179 #if ENABLE_FEATURE_CHAT_VAR_ABORT_LEN
 180                                 size_t len = strlen(arg);
 181                                 if (len > max_abort_len)
 182                                         max_abort_len = len;
 183 #endif
 184                                 llist_add_to_end(&aborts, arg);
 185 #if ENABLE_FEATURE_CHAT_CLR_ABORT
 186                         } else if (DIR_CLR_ABORT == key) {
 187                                 llist_t *l;
 188                                 // remove the string from abort conditions
 189                                 // N.B. gotta refresh maximum length too...
 190 # if ENABLE_FEATURE_CHAT_VAR_ABORT_LEN
 191                                 max_abort_len = 0;
 192 # endif
 193                                 for (l = aborts; l; l = l->link) {
 194 # if ENABLE_FEATURE_CHAT_VAR_ABORT_LEN
 195                                         size_t len = strlen(l->data);
 196 # endif
 197                                         if (strcmp(arg, l->data) == 0) {
 198                                                 llist_unlink(&aborts, l);
 199                                                 continue;
 200                                         }
 201 # if ENABLE_FEATURE_CHAT_VAR_ABORT_LEN
 202                                         if (len > max_abort_len)
 203                                                 max_abort_len = len;
 204 # endif
 205                                 }
 206 #endif
 207                         } else if (DIR_TIMEOUT == key) {
 208                                 // set new timeout
 209                                 // -1 means OFF
 210                                 timeout = atoi(arg) * 1000;
 211                                 // 0 means default
 212                                 // >0 means value in msecs
 213                                 if (!timeout)
 214                                         timeout = DEFAULT_CHAT_TIMEOUT;
 215                         } else if (DIR_ECHO == key) {
 216                                 // turn echo on/off
 217                                 // N.B. echo means dumping device input/output to stderr
 218                                 echo = onoff;
 219                         } else if (DIR_RECORD == key) {
 220                                 // turn record on/off
 221                                 // N.B. record means dumping device input to a file
 222                                         // close previous record_fd
 223                                 if (record_fd > 0)
 224                                         close(record_fd);
 225                                 // N.B. do we have to die here on open error?
 226                                 record_fd = (onoff) ? xopen(arg, O_WRONLY|O_CREAT|O_TRUNC) : -1;
 227                         } else if (DIR_SAY == key) {
 228                                 // just print argument verbatim
 229                                 // TODO: should we use full_write() to avoid unistd/stdio conflict?
 230                                 bb_error_msg("%s", arg);
 231                         }
 232                         // next, please!
 233                         argv++;
 234                 // ordinary expect-send pair!
 235                 } else {
 236                         //-----------------------
 237                         // do expect
 238                         //-----------------------
 239                         int expect_len;
 240                         size_t buf_len = 0;
 241                         size_t max_len = max_abort_len;
 242
 243                         struct pollfd pfd;
 244 #if ENABLE_FEATURE_CHAT_NOFAIL
 245                         int nofail = 0;
 246 #endif
 247                         char *expect = *argv++;
 248
 249                         // sanity check: shall we really expect something?
 250                         if (!expect)
 251                                 goto expect_done;
 252
 253 #if ENABLE_FEATURE_CHAT_NOFAIL
 254                         // if expect starts with -
 255                         if ('-' == *expect) {
 256                                 // swallow -
 257                                 expect++;
 258                                 // and enter nofail mode
 259                                 nofail++;
 260                         }
 261 #endif
 262
 263 #ifdef ___TEST___BUF___ // test behaviour with a small buffer
 264 #       undef COMMON_BUFSIZE
 265 #       define COMMON_BUFSIZE 6
 266 #endif
 267                         // expand escape sequences in expect
 268                         expect_len = unescape(expect, &expect_len /*dummy*/);
 269                         if (expect_len > max_len)
 270                                 max_len = expect_len;
 271                         // sanity check:
 272                         // we should expect more than nothing but not more than input buffer
 273                         // TODO: later we'll get rid of fixed-size buffer
 274                         if (!expect_len)
 275                                 goto expect_done;
 276                         if (max_len >= COMMON_BUFSIZE) {
 277                                 exitcode = ERR_MEM;
 278                                 goto expect_done;
 279                         }
 280
 281                         // get reply
 282                         pfd.fd = STDIN_FILENO;
 283                         pfd.events = POLLIN;
 284                         while (!exitcode
 285                             && poll(&pfd, 1, timeout) > 0
 286                             && (pfd.revents & POLLIN)
 287                         ) {
 288 #define buf bb_common_bufsiz1
 289                                 llist_t *l;
 290                                 ssize_t delta;
 291
 292                                 // read next char from device
 293                                 if (safe_read(STDIN_FILENO, buf+buf_len, 1) > 0) {
 294                                         // dump device input if RECORD fname
 295                                         if (record_fd > 0) {
 296                                                 full_write(record_fd, buf+buf_len, 1);
 297                                         }
 298                                         // dump device input if ECHO ON
 299                                         if (echo) {
 300 //                                              if (buf[buf_len] < ' ') {
 301 //                                                      full_write(STDERR_FILENO, "^", 1);
 302 //                                                      buf[buf_len] += '@';
 303 //                                              }
 304                                                 full_write(STDERR_FILENO, buf+buf_len, 1);
 305                                         }
 306                                         buf_len++;
 307                                         // move input frame if we've reached higher bound
 308                                         if (buf_len > COMMON_BUFSIZE) {
 309                                                 memmove(buf, buf+buf_len-max_len, max_len);
 310                                                 buf_len = max_len;
 311                                         }
 312                                 }
 313                                 // N.B. rule of thumb: values being looked for can
 314                                 // be found only at the end of input buffer
 315                                 // this allows to get rid of strstr() and memmem()
 316
 317                                 // TODO: make expect and abort strings processed uniformly
 318                                 // abort condition is met? -> bail out
 319                                 for (l = aborts, exitcode = ERR_ABORT; l; l = l->link, ++exitcode) {
 320                                         size_t len = strlen(l->data);
 321                                         delta = buf_len-len;
 322                                         if (delta >= 0 && !memcmp(buf+delta, l->data, len))
 323                                                 goto expect_done;
 324                                 }
 325                                 exitcode = ERR_OK;
 326
 327                                 // expected reply received? -> goto next command
 328                                 delta = buf_len - expect_len;
 329                                 if (delta >= 0 && !memcmp(buf+delta, expect, expect_len))
 330                                         goto expect_done;
 331 #undef buf
 332                         } /* while (have data) */
 333
 334                         // device timed out or unexpected reply received
 335                         exitcode = ERR_TIMEOUT;
 336  expect_done:
 337 #if ENABLE_FEATURE_CHAT_NOFAIL
 338                         // on success and when in nofail mode
 339                         // we should skip following subsend-subexpect pairs
 340                         if (nofail) {
 341                                 if (!exitcode) {
 342                                         // find last send before non-dashed expect
 343                                         while (*argv && argv[1] && '-' == argv[1][0])
 344                                                 argv += 2;
 345                                         // skip the pair
 346                                         // N.B. do we really need this?!
 347                                         if (!*argv++ || !*argv++)
 348                                                 break;
 349                                 }
 350                                 // nofail mode also clears all but IO errors (or signals)
 351                                 if (ERR_IO != exitcode)
 352                                         exitcode = ERR_OK;
 353                         }
 354 #endif
 355                         // bail out unless we expected successfully
 356                         if (exitcode)
 357                                 break;
 358
 359                         //-----------------------
 360                         // do send
 361                         //-----------------------
 362                         if (*argv) {
 363 #if ENABLE_FEATURE_CHAT_IMPLICIT_CR
 364                                 int nocr = 0; // inhibit terminating command with \r
 365 #endif
 366                                 char *loaded = NULL; // loaded command
 367                                 size_t len;
 368                                 char *buf = *argv++;
 369
 370                                 // if command starts with @
 371                                 // load "real" command from file named after @
 372                                 if ('@' == *buf) {
 373                                         // skip the @ and any following white-space
 374                                         trim(++buf);
 375                                         buf = loaded = xmalloc_xopen_read_close(buf, NULL);
 376                                 }
 377                                 // expand escape sequences in command
 378                                 len = unescape(buf, &nocr);
 379
 380                                 // send command
 381                                 alarm(timeout);
 382                                 pfd.fd = STDOUT_FILENO;
 383                                 pfd.events = POLLOUT;
 384                                 while (len && !exitcode
 385                                     && poll(&pfd, 1, -1) > 0
 386                                     && (pfd.revents & POLLOUT)
 387                                 ) {
 388 #if ENABLE_FEATURE_CHAT_SEND_ESCAPES
 389                                         // "\\d" means 1 sec delay, "\\p" means 0.01 sec delay
 390                                         // "\\K" means send BREAK
 391                                         char c = *buf;
 392                                         if ('\\' == c) {
 393                                                 c = *++buf;
 394                                                 if ('d' == c) {
 395                                                         sleep(1);
 396                                                         len--;
 397                                                         continue;
 398                                                 }
 399                                                 if ('p' == c) {
 400                                                         usleep(10000);
 401                                                         len--;
 402                                                         continue;
 403                                                 }
 404                                                 if ('K' == c) {
 405                                                         tcsendbreak(STDOUT_FILENO, 0);
 406                                                         len--;
 407                                                         continue;
 408                                                 }
 409                                                 buf--;
 410                                         }
 411                                         if (safe_write(STDOUT_FILENO, buf, 1) != 1)
 412                                                 break;
 413                                         len--;
 414                                         buf++;
 415 #else
 416                                         len -= full_write(STDOUT_FILENO, buf, len);
 417 #endif
 418                                 } /* while (can write) */
 419                                 alarm(0);
 420
 421                                 // report I/O error if there still exists at least one non-sent char
 422                                 if (len)
 423                                         exitcode = ERR_IO;
 424
 425                                 // free loaded command (if any)
 426                                 if (loaded)
 427                                         free(loaded);
 428 #if ENABLE_FEATURE_CHAT_IMPLICIT_CR
 429                                 // or terminate command with \r (if not inhibited)
 430                                 else if (!nocr)
 431                                         xwrite(STDOUT_FILENO, "\r", 1);
 432 #endif
 433                                 // bail out unless we sent command successfully
 434                                 if (exitcode)
 435                                         break;
 436                         } /* if (*argv) */
 437                 }
 438         } /* while (*argv) */
 439
 440 #if ENABLE_FEATURE_CHAT_TTY_HIFI
 441         tcsetattr(STDIN_FILENO, TCSAFLUSH, &tio0);
 442 #endif
 443
 444         return exitcode;
 445 }