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 //applet:IF_CHAT(APPLET(chat, BB_DIR_USR_SBIN, BB_SUID_DROP))
  78
  79 //kbuild:lib-$(CONFIG_CHAT) += chat.o
  80
  81 //usage:#define chat_trivial_usage
  82 //usage:       "EXPECT [SEND [EXPECT [SEND...]]]"
  83 //usage:#define chat_full_usage "\n\n"
  84 //usage:       "Useful for interacting with a modem connected to stdin/stdout.\n"
  85 //usage:       "A script consists of one or more \"expect-send\" pairs of strings,\n"
  86 //usage:       "each pair is a pair of arguments. Example:\n"
  87 //usage:       "chat '' ATZ OK ATD123456 CONNECT '' ogin: pppuser word: ppppass '~'"
  88
  89 #include "libbb.h"
  90 #include "common_bufsiz.h"
  91
  92 // default timeout: 45 sec
  93 #define DEFAULT_CHAT_TIMEOUT 45*1000
  94 // max length of "abort string",
  95 // i.e. device reply which causes termination
  96 #define MAX_ABORT_LEN 50
  97
  98 // possible exit codes
  99 enum {
 100         ERR_OK = 0,     // all's well
 101         ERR_MEM,        // read too much while expecting
 102         ERR_IO,         // signalled or I/O error
 103         ERR_TIMEOUT,    // timed out while expecting
 104         ERR_ABORT,      // first abort condition was met
 105 //      ERR_ABORT2,     // second abort condition was met
 106 //      ...
 107 };
 108
 109 // exit code
 110 #define exitcode bb_got_signal
 111
 112 // trap for critical signals
 113 static void signal_handler(UNUSED_PARAM int signo)
 114 {
 115         // report I/O error condition
 116         exitcode = ERR_IO;
 117 }
 118
 119 #if !ENABLE_FEATURE_CHAT_IMPLICIT_CR
 120 #define unescape(s, nocr) unescape(s)
 121 #endif
 122 static size_t unescape(char *s, int *nocr)
 123 {
 124         char *start = s;
 125         char *p = s;
 126
 127         while (*s) {
 128                 char c = *s;
 129                 // do we need special processing?
 130                 // standard escapes + \s for space and \N for \0
 131                 // \c inhibits terminating \r for commands and is noop for expects
 132                 if ('\\' == c) {
 133                         c = *++s;
 134                         if (c) {
 135 #if ENABLE_FEATURE_CHAT_IMPLICIT_CR
 136                                 if ('c' == c) {
 137                                         *nocr = 1;
 138                                         goto next;
 139                                 }
 140 #endif
 141                                 if ('N' == c) {
 142                                         c = '\0';
 143                                 } else if ('s' == c) {
 144                                         c = ' ';
 145 #if ENABLE_FEATURE_CHAT_NOFAIL
 146                                 // unescape leading dash only
 147                                 // TODO: and only for expect, not command string
 148                                 } else if ('-' == c && (start + 1 == s)) {
 149                                         //c = '-';
 150 #endif
 151                                 } else {
 152                                         c = bb_process_escape_sequence((const char **)&s);
 153                                         s--;
 154                                 }
 155                         }
 156                 // ^A becomes \001, ^B -- \002 and so on...
 157                 } else if ('^' == c) {
 158                         c = *++s-'@';
 159                 }
 160                 // put unescaped char
 161                 *p++ = c;
 162 #if ENABLE_FEATURE_CHAT_IMPLICIT_CR
 163  next:
 164 #endif
 165                 // next char
 166                 s++;
 167         }
 168         *p = '\0';
 169
 170         return p - start;
 171 }
 172
 173 int chat_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 174 int chat_main(int argc UNUSED_PARAM, char **argv)
 175 {
 176         int record_fd = -1;
 177         bool echo = 0;
 178         // collection of device replies which cause unconditional termination
 179         llist_t *aborts = NULL;
 180         // inactivity period
 181         int timeout = DEFAULT_CHAT_TIMEOUT;
 182         // maximum length of abort string
 183 #if ENABLE_FEATURE_CHAT_VAR_ABORT_LEN
 184         size_t max_abort_len = 0;
 185 #else
 186 #define max_abort_len MAX_ABORT_LEN
 187 #endif
 188 #if ENABLE_FEATURE_CHAT_TTY_HIFI
 189         struct termios tio0, tio;
 190 #endif
 191         // directive names
 192         enum {
 193                 DIR_HANGUP = 0,
 194                 DIR_ABORT,
 195 #if ENABLE_FEATURE_CHAT_CLR_ABORT
 196                 DIR_CLR_ABORT,
 197 #endif
 198                 DIR_TIMEOUT,
 199                 DIR_ECHO,
 200                 DIR_SAY,
 201                 DIR_RECORD,
 202         };
 203
 204         // make x* functions fail with correct exitcode
 205         xfunc_error_retval = ERR_IO;
 206
 207         // trap vanilla signals to prevent process from being killed suddenly
 208         bb_signals(0
 209                 + (1 << SIGHUP)
 210                 + (1 << SIGINT)
 211                 + (1 << SIGTERM)
 212                 + (1 << SIGPIPE)
 213                 , signal_handler);
 214
 215 #if ENABLE_FEATURE_CHAT_TTY_HIFI
 216         tcgetattr(STDIN_FILENO, &tio);
 217         tio0 = tio;
 218         cfmakeraw(&tio);
 219         tcsetattr(STDIN_FILENO, TCSAFLUSH, &tio);
 220 #endif
 221
 222 #if ENABLE_FEATURE_CHAT_SWALLOW_OPTS
 223         getopt32(argv, "vVsSE");
 224         argv += optind;
 225 #else
 226         argv++; // goto first arg
 227 #endif
 228         // handle chat expect-send pairs
 229         while (*argv) {
 230                 // directive given? process it
 231                 int key = index_in_strings(
 232                         "HANGUP\0" "ABORT\0"
 233 #if ENABLE_FEATURE_CHAT_CLR_ABORT
 234                         "CLR_ABORT\0"
 235 #endif
 236                         "TIMEOUT\0" "ECHO\0" "SAY\0" "RECORD\0"
 237                         , *argv
 238                 );
 239                 if (key >= 0) {
 240                         // cache directive value
 241                         char *arg = *++argv;
 242                         // OFF -> 0, anything else -> 1
 243                         bool onoff = (0 != strcmp("OFF", arg));
 244                         // process directive
 245                         if (DIR_HANGUP == key) {
 246                                 // turn SIGHUP on/off
 247                                 signal(SIGHUP, onoff ? signal_handler : SIG_IGN);
 248                         } else if (DIR_ABORT == key) {
 249                                 // append the string to abort conditions
 250 #if ENABLE_FEATURE_CHAT_VAR_ABORT_LEN
 251                                 size_t len = strlen(arg);
 252                                 if (len > max_abort_len)
 253                                         max_abort_len = len;
 254 #endif
 255                                 llist_add_to_end(&aborts, arg);
 256 #if ENABLE_FEATURE_CHAT_CLR_ABORT
 257                         } else if (DIR_CLR_ABORT == key) {
 258                                 llist_t *l;
 259                                 // remove the string from abort conditions
 260                                 // N.B. gotta refresh maximum length too...
 261 # if ENABLE_FEATURE_CHAT_VAR_ABORT_LEN
 262                                 max_abort_len = 0;
 263 # endif
 264                                 for (l = aborts; l; l = l->link) {
 265 # if ENABLE_FEATURE_CHAT_VAR_ABORT_LEN
 266                                         size_t len = strlen(l->data);
 267 # endif
 268                                         if (strcmp(arg, l->data) == 0) {
 269                                                 llist_unlink(&aborts, l);
 270                                                 continue;
 271                                         }
 272 # if ENABLE_FEATURE_CHAT_VAR_ABORT_LEN
 273                                         if (len > max_abort_len)
 274                                                 max_abort_len = len;
 275 # endif
 276                                 }
 277 #endif
 278                         } else if (DIR_TIMEOUT == key) {
 279                                 // set new timeout
 280                                 // -1 means OFF
 281                                 timeout = atoi(arg) * 1000;
 282                                 // 0 means default
 283                                 // >0 means value in msecs
 284                                 if (!timeout)
 285                                         timeout = DEFAULT_CHAT_TIMEOUT;
 286                         } else if (DIR_ECHO == key) {
 287                                 // turn echo on/off
 288                                 // N.B. echo means dumping device input/output to stderr
 289                                 echo = onoff;
 290                         } else if (DIR_RECORD == key) {
 291                                 // turn record on/off
 292                                 // N.B. record means dumping device input to a file
 293                                         // close previous record_fd
 294                                 if (record_fd > 0)
 295                                         close(record_fd);
 296                                 // N.B. do we have to die here on open error?
 297                                 record_fd = (onoff) ? xopen(arg, O_WRONLY|O_CREAT|O_TRUNC) : -1;
 298                         } else if (DIR_SAY == key) {
 299                                 // just print argument verbatim
 300                                 // TODO: should we use full_write() to avoid unistd/stdio conflict?
 301                                 bb_error_msg("%s", arg);
 302                         }
 303                         // next, please!
 304                         argv++;
 305                 // ordinary expect-send pair!
 306                 } else {
 307                         //-----------------------
 308                         // do expect
 309                         //-----------------------
 310                         int expect_len;
 311                         size_t buf_len = 0;
 312                         size_t max_len = max_abort_len;
 313
 314                         struct pollfd pfd;
 315 #if ENABLE_FEATURE_CHAT_NOFAIL
 316                         int nofail = 0;
 317 #endif
 318                         char *expect = *argv++;
 319
 320                         // sanity check: shall we really expect something?
 321                         if (!expect)
 322                                 goto expect_done;
 323
 324 #if ENABLE_FEATURE_CHAT_NOFAIL
 325                         // if expect starts with -
 326                         if ('-' == *expect) {
 327                                 // swallow -
 328                                 expect++;
 329                                 // and enter nofail mode
 330                                 nofail++;
 331                         }
 332 #endif
 333
 334 #ifdef ___TEST___BUF___ // test behaviour with a small buffer
 335 #       undef COMMON_BUFSIZE
 336 #       define COMMON_BUFSIZE 6
 337 #endif
 338                         // expand escape sequences in expect
 339                         expect_len = unescape(expect, &expect_len /*dummy*/);
 340                         if (expect_len > max_len)
 341                                 max_len = expect_len;
 342                         // sanity check:
 343                         // we should expect more than nothing but not more than input buffer
 344                         // TODO: later we'll get rid of fixed-size buffer
 345                         if (!expect_len)
 346                                 goto expect_done;
 347                         if (max_len >= COMMON_BUFSIZE) {
 348                                 exitcode = ERR_MEM;
 349                                 goto expect_done;
 350                         }
 351
 352                         // get reply
 353                         pfd.fd = STDIN_FILENO;
 354                         pfd.events = POLLIN;
 355                         while (!exitcode
 356                             && poll(&pfd, 1, timeout) > 0
 357                             && (pfd.revents & POLLIN)
 358                         ) {
 359                                 llist_t *l;
 360                                 ssize_t delta;
 361 #define buf bb_common_bufsiz1
 362                                 setup_common_bufsiz();
 363
 364                                 // read next char from device
 365                                 if (safe_read(STDIN_FILENO, buf+buf_len, 1) > 0) {
 366                                         // dump device input if RECORD fname
 367                                         if (record_fd > 0) {
 368                                                 full_write(record_fd, buf+buf_len, 1);
 369                                         }
 370                                         // dump device input if ECHO ON
 371                                         if (echo) {
 372 //                                              if (buf[buf_len] < ' ') {
 373 //                                                      full_write(STDERR_FILENO, "^", 1);
 374 //                                                      buf[buf_len] += '@';
 375 //                                              }
 376                                                 full_write(STDERR_FILENO, buf+buf_len, 1);
 377                                         }
 378                                         buf_len++;
 379                                         // move input frame if we've reached higher bound
 380                                         if (buf_len > COMMON_BUFSIZE) {
 381                                                 memmove(buf, buf+buf_len-max_len, max_len);
 382                                                 buf_len = max_len;
 383                                         }
 384                                 }
 385                                 // N.B. rule of thumb: values being looked for can
 386                                 // be found only at the end of input buffer
 387                                 // this allows to get rid of strstr() and memmem()
 388
 389                                 // TODO: make expect and abort strings processed uniformly
 390                                 // abort condition is met? -> bail out
 391                                 for (l = aborts, exitcode = ERR_ABORT; l; l = l->link, ++exitcode) {
 392                                         size_t len = strlen(l->data);
 393                                         delta = buf_len-len;
 394                                         if (delta >= 0 && !memcmp(buf+delta, l->data, len))
 395                                                 goto expect_done;
 396                                 }
 397                                 exitcode = ERR_OK;
 398
 399                                 // expected reply received? -> goto next command
 400                                 delta = buf_len - expect_len;
 401                                 if (delta >= 0 && !memcmp(buf+delta, expect, expect_len))
 402                                         goto expect_done;
 403 #undef buf
 404                         } /* while (have data) */
 405
 406                         // device timed out or unexpected reply received
 407                         exitcode = ERR_TIMEOUT;
 408  expect_done:
 409 #if ENABLE_FEATURE_CHAT_NOFAIL
 410                         // on success and when in nofail mode
 411                         // we should skip following subsend-subexpect pairs
 412                         if (nofail) {
 413                                 if (!exitcode) {
 414                                         // find last send before non-dashed expect
 415                                         while (*argv && argv[1] && '-' == argv[1][0])
 416                                                 argv += 2;
 417                                         // skip the pair
 418                                         // N.B. do we really need this?!
 419                                         if (!*argv++ || !*argv++)
 420                                                 break;
 421                                 }
 422                                 // nofail mode also clears all but IO errors (or signals)
 423                                 if (ERR_IO != exitcode)
 424                                         exitcode = ERR_OK;
 425                         }
 426 #endif
 427                         // bail out unless we expected successfully
 428                         if (exitcode)
 429                                 break;
 430
 431                         //-----------------------
 432                         // do send
 433                         //-----------------------
 434                         if (*argv) {
 435 #if ENABLE_FEATURE_CHAT_IMPLICIT_CR
 436                                 int nocr = 0; // inhibit terminating command with \r
 437 #endif
 438                                 char *loaded = NULL; // loaded command
 439                                 size_t len;
 440                                 char *buf = *argv++;
 441
 442                                 // if command starts with @
 443                                 // load "real" command from file named after @
 444                                 if ('@' == *buf) {
 445                                         // skip the @ and any following white-space
 446                                         trim(++buf);
 447                                         buf = loaded = xmalloc_xopen_read_close(buf, NULL);
 448                                 }
 449                                 // expand escape sequences in command
 450                                 len = unescape(buf, &nocr);
 451
 452                                 // send command
 453                                 alarm(timeout);
 454                                 pfd.fd = STDOUT_FILENO;
 455                                 pfd.events = POLLOUT;
 456                                 while (len && !exitcode
 457                                     && poll(&pfd, 1, -1) > 0
 458                                     && (pfd.revents & POLLOUT)
 459                                 ) {
 460 #if ENABLE_FEATURE_CHAT_SEND_ESCAPES
 461                                         // "\\d" means 1 sec delay, "\\p" means 0.01 sec delay
 462                                         // "\\K" means send BREAK
 463                                         char c = *buf;
 464                                         if ('\\' == c) {
 465                                                 c = *++buf;
 466                                                 if ('d' == c) {
 467                                                         sleep(1);
 468                                                         len--;
 469                                                         continue;
 470                                                 }
 471                                                 if ('p' == c) {
 472                                                         usleep(10000);
 473                                                         len--;
 474                                                         continue;
 475                                                 }
 476                                                 if ('K' == c) {
 477                                                         tcsendbreak(STDOUT_FILENO, 0);
 478                                                         len--;
 479                                                         continue;
 480                                                 }
 481                                                 buf--;
 482                                         }
 483                                         if (safe_write(STDOUT_FILENO, buf, 1) != 1)
 484                                                 break;
 485                                         len--;
 486                                         buf++;
 487 #else
 488                                         len -= full_write(STDOUT_FILENO, buf, len);
 489 #endif
 490                                 } /* while (can write) */
 491                                 alarm(0);
 492
 493                                 // report I/O error if there still exists at least one non-sent char
 494                                 if (len)
 495                                         exitcode = ERR_IO;
 496
 497                                 // free loaded command (if any)
 498                                 if (loaded)
 499                                         free(loaded);
 500 #if ENABLE_FEATURE_CHAT_IMPLICIT_CR
 501                                 // or terminate command with \r (if not inhibited)
 502                                 else if (!nocr)
 503                                         xwrite(STDOUT_FILENO, "\r", 1);
 504 #endif
 505                                 // bail out unless we sent command successfully
 506                                 if (exitcode)
 507                                         break;
 508                         } /* if (*argv) */
 509                 }
 510         } /* while (*argv) */
 511
 512 #if ENABLE_FEATURE_CHAT_TTY_HIFI
 513         tcsetattr(STDIN_FILENO, TCSAFLUSH, &tio0);
 514 #endif
 515
 516         return exitcode;
 517 }