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 //config:config CHAT
  11 //config:       bool "chat"
  12 //config:       default y
  13 //config:       help
  14 //config:         Simple chat utility.
  15 //config:
  16 //config:config FEATURE_CHAT_NOFAIL
  17 //config:       bool "Enable NOFAIL expect strings"
  18 //config:       depends on CHAT
  19 //config:       default y
  20 //config:       help
  21 //config:         When enabled expect strings which are started with a dash trigger
  22 //config:         no-fail mode. That is when expectation is not met within timeout
  23 //config:         the script is not terminated but sends next SEND string and waits
  24 //config:         for next EXPECT string. This allows to compose far more flexible
  25 //config:         scripts.
  26 //config:
  27 //config:config FEATURE_CHAT_TTY_HIFI
  28 //config:       bool "Force STDIN to be a TTY"
  29 //config:       depends on CHAT
  30 //config:       default n
  31 //config:       help
  32 //config:         Original chat always treats STDIN as a TTY device and sets for it
  33 //config:         so-called raw mode. This option turns on such behaviour.
  34 //config:
  35 //config:config FEATURE_CHAT_IMPLICIT_CR
  36 //config:       bool "Enable implicit Carriage Return"
  37 //config:       depends on CHAT
  38 //config:       default y
  39 //config:       help
  40 //config:         When enabled make chat to terminate all SEND strings with a "\r"
  41 //config:         unless "\c" is met anywhere in the string.
  42 //config:
  43 //config:config FEATURE_CHAT_SWALLOW_OPTS
  44 //config:       bool "Swallow options"
  45 //config:       depends on CHAT
  46 //config:       default y
  47 //config:       help
  48 //config:         Busybox chat require no options. To make it not fail when used
  49 //config:         in place of original chat (which has a bunch of options) turn
  50 //config:         this on.
  51 //config:
  52 //config:config FEATURE_CHAT_SEND_ESCAPES
  53 //config:       bool "Support weird SEND escapes"
  54 //config:       depends on CHAT
  55 //config:       default y
  56 //config:       help
  57 //config:         Original chat uses some escape sequences in SEND arguments which
  58 //config:         are not sent to device but rather performs special actions.
  59 //config:         E.g. "\K" means to send a break sequence to device.
  60 //config:         "\d" delays execution for a second, "\p" -- for a 1/100 of second.
  61 //config:         Before turning this option on think twice: do you really need them?
  62 //config:
  63 //config:config FEATURE_CHAT_VAR_ABORT_LEN
  64 //config:       bool "Support variable-length ABORT conditions"
  65 //config:       depends on CHAT
  66 //config:       default y
  67 //config:       help
  68 //config:         Original chat uses fixed 50-bytes length ABORT conditions. Say N here.
  69 //config:
  70 //config:config FEATURE_CHAT_CLR_ABORT
  71 //config:       bool "Support revoking of ABORT conditions"
  72 //config:       depends on CHAT
  73 //config:       default y
  74 //config:       help
  75 //config:         Support CLR_ABORT directive.
  76
  77 //usage:#define chat_trivial_usage
  78 //usage:       "EXPECT [SEND [EXPECT [SEND...]]]"
  79 //usage:#define chat_full_usage "\n\n"
  80 //usage:       "Useful for interacting with a modem connected to stdin/stdout.\n"
  81 //usage:       "A script consists of one or more \"expect-send\" pairs of strings,\n"
  82 //usage:       "each pair is a pair of arguments. Example:\n"
  83 //usage:       "chat '' ATZ OK ATD123456 CONNECT '' ogin: pppuser word: ppppass '~'"
  84
  85 #include "libbb.h"
  86 #include "common_bufsiz.h"
  87
  88 // default timeout: 45 sec
  89 #define DEFAULT_CHAT_TIMEOUT 45*1000
  90 // max length of "abort string",
  91 // i.e. device reply which causes termination
  92 #define MAX_ABORT_LEN 50
  93
  94 // possible exit codes
  95 enum {
  96         ERR_OK = 0,     // all's well
  97         ERR_MEM,        // read too much while expecting
  98         ERR_IO,         // signalled or I/O error
  99         ERR_TIMEOUT,    // timed out while expecting
 100         ERR_ABORT,      // first abort condition was met
 101 //      ERR_ABORT2,     // second abort condition was met
 102 //      ...
 103 };
 104
 105 // exit code
 106 #define exitcode bb_got_signal
 107
 108 // trap for critical signals
 109 static void signal_handler(UNUSED_PARAM int signo)
 110 {
 111         // report I/O error condition
 112         exitcode = ERR_IO;
 113 }
 114
 115 #if !ENABLE_FEATURE_CHAT_IMPLICIT_CR
 116 #define unescape(s, nocr) unescape(s)
 117 #endif
 118 static size_t unescape(char *s, int *nocr)
 119 {
 120         char *start = s;
 121         char *p = s;
 122
 123         while (*s) {
 124                 char c = *s;
 125                 // do we need special processing?
 126                 // standard escapes + \s for space and \N for \0
 127                 // \c inhibits terminating \r for commands and is noop for expects
 128                 if ('\\' == c) {
 129                         c = *++s;
 130                         if (c) {
 131 #if ENABLE_FEATURE_CHAT_IMPLICIT_CR
 132                                 if ('c' == c) {
 133                                         *nocr = 1;
 134                                         goto next;
 135                                 }
 136 #endif
 137                                 if ('N' == c) {
 138                                         c = '\0';
 139                                 } else if ('s' == c) {
 140                                         c = ' ';
 141 #if ENABLE_FEATURE_CHAT_NOFAIL
 142                                 // unescape leading dash only
 143                                 // TODO: and only for expect, not command string
 144                                 } else if ('-' == c && (start + 1 == s)) {
 145                                         //c = '-';
 146 #endif
 147                                 } else {
 148                                         c = bb_process_escape_sequence((const char **)&s);
 149                                         s--;
 150                                 }
 151                         }
 152                 // ^A becomes \001, ^B -- \002 and so on...
 153                 } else if ('^' == c) {
 154                         c = *++s-'@';
 155                 }
 156                 // put unescaped char
 157                 *p++ = c;
 158 #if ENABLE_FEATURE_CHAT_IMPLICIT_CR
 159  next:
 160 #endif
 161                 // next char
 162                 s++;
 163         }
 164         *p = '\0';
 165
 166         return p - start;
 167 }
 168
 169 int chat_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 170 int chat_main(int argc UNUSED_PARAM, char **argv)
 171 {
 172         int record_fd = -1;
 173         bool echo = 0;
 174         // collection of device replies which cause unconditional termination
 175         llist_t *aborts = NULL;
 176         // inactivity period
 177         int timeout = DEFAULT_CHAT_TIMEOUT;
 178         // maximum length of abort string
 179 #if ENABLE_FEATURE_CHAT_VAR_ABORT_LEN
 180         size_t max_abort_len = 0;
 181 #else
 182 #define max_abort_len MAX_ABORT_LEN
 183 #endif
 184 #if ENABLE_FEATURE_CHAT_TTY_HIFI
 185         struct termios tio0, tio;
 186 #endif
 187         // directive names
 188         enum {
 189                 DIR_HANGUP = 0,
 190                 DIR_ABORT,
 191 #if ENABLE_FEATURE_CHAT_CLR_ABORT
 192                 DIR_CLR_ABORT,
 193 #endif
 194                 DIR_TIMEOUT,
 195                 DIR_ECHO,
 196                 DIR_SAY,
 197                 DIR_RECORD,
 198         };
 199
 200         // make x* functions fail with correct exitcode
 201         xfunc_error_retval = ERR_IO;
 202
 203         // trap vanilla signals to prevent process from being killed suddenly
 204         bb_signals(0
 205                 + (1 << SIGHUP)
 206                 + (1 << SIGINT)
 207                 + (1 << SIGTERM)
 208                 + (1 << SIGPIPE)
 209                 , signal_handler);
 210
 211 #if ENABLE_FEATURE_CHAT_TTY_HIFI
 212         tcgetattr(STDIN_FILENO, &tio);
 213         tio0 = tio;
 214         cfmakeraw(&tio);
 215         tcsetattr(STDIN_FILENO, TCSAFLUSH, &tio);
 216 #endif
 217
 218 #if ENABLE_FEATURE_CHAT_SWALLOW_OPTS
 219         getopt32(argv, "vVsSE");
 220         argv += optind;
 221 #else
 222         argv++; // goto first arg
 223 #endif
 224         // handle chat expect-send pairs
 225         while (*argv) {
 226                 // directive given? process it
 227                 int key = index_in_strings(
 228                         "HANGUP\0" "ABORT\0"
 229 #if ENABLE_FEATURE_CHAT_CLR_ABORT
 230                         "CLR_ABORT\0"
 231 #endif
 232                         "TIMEOUT\0" "ECHO\0" "SAY\0" "RECORD\0"
 233                         , *argv
 234                 );
 235                 if (key >= 0) {
 236                         // cache directive value
 237                         char *arg = *++argv;
 238                         // OFF -> 0, anything else -> 1
 239                         bool onoff = (0 != strcmp("OFF", arg));
 240                         // process directive
 241                         if (DIR_HANGUP == key) {
 242                                 // turn SIGHUP on/off
 243                                 signal(SIGHUP, onoff ? signal_handler : SIG_IGN);
 244                         } else if (DIR_ABORT == key) {
 245                                 // append the string to abort conditions
 246 #if ENABLE_FEATURE_CHAT_VAR_ABORT_LEN
 247                                 size_t len = strlen(arg);
 248                                 if (len > max_abort_len)
 249                                         max_abort_len = len;
 250 #endif
 251                                 llist_add_to_end(&aborts, arg);
 252 #if ENABLE_FEATURE_CHAT_CLR_ABORT
 253                         } else if (DIR_CLR_ABORT == key) {
 254                                 llist_t *l;
 255                                 // remove the string from abort conditions
 256                                 // N.B. gotta refresh maximum length too...
 257 # if ENABLE_FEATURE_CHAT_VAR_ABORT_LEN
 258                                 max_abort_len = 0;
 259 # endif
 260                                 for (l = aborts; l; l = l->link) {
 261 # if ENABLE_FEATURE_CHAT_VAR_ABORT_LEN
 262                                         size_t len = strlen(l->data);
 263 # endif
 264                                         if (strcmp(arg, l->data) == 0) {
 265                                                 llist_unlink(&aborts, l);
 266                                                 continue;
 267                                         }
 268 # if ENABLE_FEATURE_CHAT_VAR_ABORT_LEN
 269                                         if (len > max_abort_len)
 270                                                 max_abort_len = len;
 271 # endif
 272                                 }
 273 #endif
 274                         } else if (DIR_TIMEOUT == key) {
 275                                 // set new timeout
 276                                 // -1 means OFF
 277                                 timeout = atoi(arg) * 1000;
 278                                 // 0 means default
 279                                 // >0 means value in msecs
 280                                 if (!timeout)
 281                                         timeout = DEFAULT_CHAT_TIMEOUT;
 282                         } else if (DIR_ECHO == key) {
 283                                 // turn echo on/off
 284                                 // N.B. echo means dumping device input/output to stderr
 285                                 echo = onoff;
 286                         } else if (DIR_RECORD == key) {
 287                                 // turn record on/off
 288                                 // N.B. record means dumping device input to a file
 289                                         // close previous record_fd
 290                                 if (record_fd > 0)
 291                                         close(record_fd);
 292                                 // N.B. do we have to die here on open error?
 293                                 record_fd = (onoff) ? xopen(arg, O_WRONLY|O_CREAT|O_TRUNC) : -1;
 294                         } else if (DIR_SAY == key) {
 295                                 // just print argument verbatim
 296                                 // TODO: should we use full_write() to avoid unistd/stdio conflict?
 297                                 bb_error_msg("%s", arg);
 298                         }
 299                         // next, please!
 300                         argv++;
 301                 // ordinary expect-send pair!
 302                 } else {
 303                         //-----------------------
 304                         // do expect
 305                         //-----------------------
 306                         int expect_len;
 307                         size_t buf_len = 0;
 308                         size_t max_len = max_abort_len;
 309
 310                         struct pollfd pfd;
 311 #if ENABLE_FEATURE_CHAT_NOFAIL
 312                         int nofail = 0;
 313 #endif
 314                         char *expect = *argv++;
 315
 316                         // sanity check: shall we really expect something?
 317                         if (!expect)
 318                                 goto expect_done;
 319
 320 #if ENABLE_FEATURE_CHAT_NOFAIL
 321                         // if expect starts with -
 322                         if ('-' == *expect) {
 323                                 // swallow -
 324                                 expect++;
 325                                 // and enter nofail mode
 326                                 nofail++;
 327                         }
 328 #endif
 329
 330 #ifdef ___TEST___BUF___ // test behaviour with a small buffer
 331 #       undef COMMON_BUFSIZE
 332 #       define COMMON_BUFSIZE 6
 333 #endif
 334                         // expand escape sequences in expect
 335                         expect_len = unescape(expect, &expect_len /*dummy*/);
 336                         if (expect_len > max_len)
 337                                 max_len = expect_len;
 338                         // sanity check:
 339                         // we should expect more than nothing but not more than input buffer
 340                         // TODO: later we'll get rid of fixed-size buffer
 341                         if (!expect_len)
 342                                 goto expect_done;
 343                         if (max_len >= COMMON_BUFSIZE) {
 344                                 exitcode = ERR_MEM;
 345                                 goto expect_done;
 346                         }
 347
 348                         // get reply
 349                         pfd.fd = STDIN_FILENO;
 350                         pfd.events = POLLIN;
 351                         while (!exitcode
 352                             && poll(&pfd, 1, timeout) > 0
 353                             && (pfd.revents & POLLIN)
 354                         ) {
 355                                 llist_t *l;
 356                                 ssize_t delta;
 357 #define buf bb_common_bufsiz1
 358                                 setup_common_bufsiz();
 359
 360                                 // read next char from device
 361                                 if (safe_read(STDIN_FILENO, buf+buf_len, 1) > 0) {
 362                                         // dump device input if RECORD fname
 363                                         if (record_fd > 0) {
 364                                                 full_write(record_fd, buf+buf_len, 1);
 365                                         }
 366                                         // dump device input if ECHO ON
 367                                         if (echo) {
 368 //                                              if (buf[buf_len] < ' ') {
 369 //                                                      full_write(STDERR_FILENO, "^", 1);
 370 //                                                      buf[buf_len] += '@';
 371 //                                              }
 372                                                 full_write(STDERR_FILENO, buf+buf_len, 1);
 373                                         }
 374                                         buf_len++;
 375                                         // move input frame if we've reached higher bound
 376                                         if (buf_len > COMMON_BUFSIZE) {
 377                                                 memmove(buf, buf+buf_len-max_len, max_len);
 378                                                 buf_len = max_len;
 379                                         }
 380                                 }
 381                                 // N.B. rule of thumb: values being looked for can
 382                                 // be found only at the end of input buffer
 383                                 // this allows to get rid of strstr() and memmem()
 384
 385                                 // TODO: make expect and abort strings processed uniformly
 386                                 // abort condition is met? -> bail out
 387                                 for (l = aborts, exitcode = ERR_ABORT; l; l = l->link, ++exitcode) {
 388                                         size_t len = strlen(l->data);
 389                                         delta = buf_len-len;
 390                                         if (delta >= 0 && !memcmp(buf+delta, l->data, len))
 391                                                 goto expect_done;
 392                                 }
 393                                 exitcode = ERR_OK;
 394
 395                                 // expected reply received? -> goto next command
 396                                 delta = buf_len - expect_len;
 397                                 if (delta >= 0 && !memcmp(buf+delta, expect, expect_len))
 398                                         goto expect_done;
 399 #undef buf
 400                         } /* while (have data) */
 401
 402                         // device timed out or unexpected reply received
 403                         exitcode = ERR_TIMEOUT;
 404  expect_done:
 405 #if ENABLE_FEATURE_CHAT_NOFAIL
 406                         // on success and when in nofail mode
 407                         // we should skip following subsend-subexpect pairs
 408                         if (nofail) {
 409                                 if (!exitcode) {
 410                                         // find last send before non-dashed expect
 411                                         while (*argv && argv[1] && '-' == argv[1][0])
 412                                                 argv += 2;
 413                                         // skip the pair
 414                                         // N.B. do we really need this?!
 415                                         if (!*argv++ || !*argv++)
 416                                                 break;
 417                                 }
 418                                 // nofail mode also clears all but IO errors (or signals)
 419                                 if (ERR_IO != exitcode)
 420                                         exitcode = ERR_OK;
 421                         }
 422 #endif
 423                         // bail out unless we expected successfully
 424                         if (exitcode)
 425                                 break;
 426
 427                         //-----------------------
 428                         // do send
 429                         //-----------------------
 430                         if (*argv) {
 431 #if ENABLE_FEATURE_CHAT_IMPLICIT_CR
 432                                 int nocr = 0; // inhibit terminating command with \r
 433 #endif
 434                                 char *loaded = NULL; // loaded command
 435                                 size_t len;
 436                                 char *buf = *argv++;
 437
 438                                 // if command starts with @
 439                                 // load "real" command from file named after @
 440                                 if ('@' == *buf) {
 441                                         // skip the @ and any following white-space
 442                                         trim(++buf);
 443                                         buf = loaded = xmalloc_xopen_read_close(buf, NULL);
 444                                 }
 445                                 // expand escape sequences in command
 446                                 len = unescape(buf, &nocr);
 447
 448                                 // send command
 449                                 alarm(timeout);
 450                                 pfd.fd = STDOUT_FILENO;
 451                                 pfd.events = POLLOUT;
 452                                 while (len && !exitcode
 453                                     && poll(&pfd, 1, -1) > 0
 454                                     && (pfd.revents & POLLOUT)
 455                                 ) {
 456 #if ENABLE_FEATURE_CHAT_SEND_ESCAPES
 457                                         // "\\d" means 1 sec delay, "\\p" means 0.01 sec delay
 458                                         // "\\K" means send BREAK
 459                                         char c = *buf;
 460                                         if ('\\' == c) {
 461                                                 c = *++buf;
 462                                                 if ('d' == c) {
 463                                                         sleep(1);
 464                                                         len--;
 465                                                         continue;
 466                                                 }
 467                                                 if ('p' == c) {
 468                                                         usleep(10000);
 469                                                         len--;
 470                                                         continue;
 471                                                 }
 472                                                 if ('K' == c) {
 473                                                         tcsendbreak(STDOUT_FILENO, 0);
 474                                                         len--;
 475                                                         continue;
 476                                                 }
 477                                                 buf--;
 478                                         }
 479                                         if (safe_write(STDOUT_FILENO, buf, 1) != 1)
 480                                                 break;
 481                                         len--;
 482                                         buf++;
 483 #else
 484                                         len -= full_write(STDOUT_FILENO, buf, len);
 485 #endif
 486                                 } /* while (can write) */
 487                                 alarm(0);
 488
 489                                 // report I/O error if there still exists at least one non-sent char
 490                                 if (len)
 491                                         exitcode = ERR_IO;
 492
 493                                 // free loaded command (if any)
 494                                 if (loaded)
 495                                         free(loaded);
 496 #if ENABLE_FEATURE_CHAT_IMPLICIT_CR
 497                                 // or terminate command with \r (if not inhibited)
 498                                 else if (!nocr)
 499                                         xwrite(STDOUT_FILENO, "\r", 1);
 500 #endif
 501                                 // bail out unless we sent command successfully
 502                                 if (exitcode)
 503                                         break;
 504                         } /* if (*argv) */
 505                 }
 506         } /* while (*argv) */
 507
 508 #if ENABLE_FEATURE_CHAT_TTY_HIFI
 509         tcsetattr(STDIN_FILENO, TCSAFLUSH, &tio0);
 510 #endif
 511
 512         return exitcode;
 513 }