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 (6.6 kb)"
  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 \"expect-send\" argument pairs.\n"
  86 //usage:       "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 //TODO: use set_termios_to_raw()
 217         tcgetattr(STDIN_FILENO, &tio);
 218         tio0 = tio;
 219         cfmakeraw(&tio);
 220         tcsetattr(STDIN_FILENO, TCSAFLUSH, &tio);
 221 #endif
 222
 223 #if ENABLE_FEATURE_CHAT_SWALLOW_OPTS
 224         getopt32(argv, "vVsSE");
 225         argv += optind;
 226 #else
 227         argv++; // goto first arg
 228 #endif
 229         // handle chat expect-send pairs
 230         while (*argv) {
 231                 // directive given? process it
 232                 int key = index_in_strings(
 233                         "HANGUP\0" "ABORT\0"
 234 #if ENABLE_FEATURE_CHAT_CLR_ABORT
 235                         "CLR_ABORT\0"
 236 #endif
 237                         "TIMEOUT\0" "ECHO\0" "SAY\0" "RECORD\0"
 238                         , *argv
 239                 );
 240                 if (key >= 0) {
 241                         // cache directive value
 242                         char *arg = *++argv;
 243                         // OFF -> 0, anything else -> 1
 244                         bool onoff = (0 != strcmp("OFF", arg));
 245                         // process directive
 246                         if (DIR_HANGUP == key) {
 247                                 // turn SIGHUP on/off
 248                                 signal(SIGHUP, onoff ? signal_handler : SIG_IGN);
 249                         } else if (DIR_ABORT == key) {
 250                                 // append the string to abort conditions
 251 #if ENABLE_FEATURE_CHAT_VAR_ABORT_LEN
 252                                 size_t len = strlen(arg);
 253                                 if (len > max_abort_len)
 254                                         max_abort_len = len;
 255 #endif
 256                                 llist_add_to_end(&aborts, arg);
 257 #if ENABLE_FEATURE_CHAT_CLR_ABORT
 258                         } else if (DIR_CLR_ABORT == key) {
 259                                 llist_t *l;
 260                                 // remove the string from abort conditions
 261                                 // N.B. gotta refresh maximum length too...
 262 # if ENABLE_FEATURE_CHAT_VAR_ABORT_LEN
 263                                 max_abort_len = 0;
 264 # endif
 265                                 for (l = aborts; l; l = l->link) {
 266 # if ENABLE_FEATURE_CHAT_VAR_ABORT_LEN
 267                                         size_t len = strlen(l->data);
 268 # endif
 269                                         if (strcmp(arg, l->data) == 0) {
 270                                                 llist_unlink(&aborts, l);
 271                                                 continue;
 272                                         }
 273 # if ENABLE_FEATURE_CHAT_VAR_ABORT_LEN
 274                                         if (len > max_abort_len)
 275                                                 max_abort_len = len;
 276 # endif
 277                                 }
 278 #endif
 279                         } else if (DIR_TIMEOUT == key) {
 280                                 // set new timeout
 281                                 // -1 means OFF
 282                                 timeout = atoi(arg) * 1000;
 283                                 // 0 means default
 284                                 // >0 means value in msecs
 285                                 if (!timeout)
 286                                         timeout = DEFAULT_CHAT_TIMEOUT;
 287                         } else if (DIR_ECHO == key) {
 288                                 // turn echo on/off
 289                                 // N.B. echo means dumping device input/output to stderr
 290                                 echo = onoff;
 291                         } else if (DIR_RECORD == key) {
 292                                 // turn record on/off
 293                                 // N.B. record means dumping device input to a file
 294                                         // close previous record_fd
 295                                 if (record_fd > 0)
 296                                         close(record_fd);
 297                                 // N.B. do we have to die here on open error?
 298                                 record_fd = (onoff) ? xopen(arg, O_WRONLY|O_CREAT|O_TRUNC) : -1;
 299                         } else if (DIR_SAY == key) {
 300                                 // just print argument verbatim
 301                                 // TODO: should we use full_write() to avoid unistd/stdio conflict?
 302                                 bb_error_msg("%s", arg);
 303                         }
 304                         // next, please!
 305                         argv++;
 306                 // ordinary expect-send pair!
 307                 } else {
 308                         //-----------------------
 309                         // do expect
 310                         //-----------------------
 311                         int expect_len;
 312                         size_t buf_len = 0;
 313                         size_t max_len = max_abort_len;
 314
 315                         struct pollfd pfd;
 316 #if ENABLE_FEATURE_CHAT_NOFAIL
 317                         int nofail = 0;
 318 #endif
 319                         char *expect = *argv++;
 320
 321                         // sanity check: shall we really expect something?
 322                         if (!expect)
 323                                 goto expect_done;
 324
 325 #if ENABLE_FEATURE_CHAT_NOFAIL
 326                         // if expect starts with -
 327                         if ('-' == *expect) {
 328                                 // swallow -
 329                                 expect++;
 330                                 // and enter nofail mode
 331                                 nofail++;
 332                         }
 333 #endif
 334
 335 #ifdef ___TEST___BUF___ // test behaviour with a small buffer
 336 #       undef COMMON_BUFSIZE
 337 #       define COMMON_BUFSIZE 6
 338 #endif
 339                         // expand escape sequences in expect
 340                         expect_len = unescape(expect, &expect_len /*dummy*/);
 341                         if (expect_len > max_len)
 342                                 max_len = expect_len;
 343                         // sanity check:
 344                         // we should expect more than nothing but not more than input buffer
 345                         // TODO: later we'll get rid of fixed-size buffer
 346                         if (!expect_len)
 347                                 goto expect_done;
 348                         if (max_len >= COMMON_BUFSIZE) {
 349                                 exitcode = ERR_MEM;
 350                                 goto expect_done;
 351                         }
 352
 353                         // get reply
 354                         pfd.fd = STDIN_FILENO;
 355                         pfd.events = POLLIN;
 356                         while (!exitcode
 357                             && poll(&pfd, 1, timeout) > 0
 358                             && (pfd.revents & POLLIN)
 359                         ) {
 360                                 llist_t *l;
 361                                 ssize_t delta;
 362 #define buf bb_common_bufsiz1
 363                                 setup_common_bufsiz();
 364
 365                                 // read next char from device
 366                                 if (safe_read(STDIN_FILENO, buf+buf_len, 1) > 0) {
 367                                         // dump device input if RECORD fname
 368                                         if (record_fd > 0) {
 369                                                 full_write(record_fd, buf+buf_len, 1);
 370                                         }
 371                                         // dump device input if ECHO ON
 372                                         if (echo) {
 373 //                                              if (buf[buf_len] < ' ') {
 374 //                                                      full_write(STDERR_FILENO, "^", 1);
 375 //                                                      buf[buf_len] += '@';
 376 //                                              }
 377                                                 full_write(STDERR_FILENO, buf+buf_len, 1);
 378                                         }
 379                                         buf_len++;
 380                                         // move input frame if we've reached higher bound
 381                                         if (buf_len > COMMON_BUFSIZE) {
 382                                                 memmove(buf, buf+buf_len-max_len, max_len);
 383                                                 buf_len = max_len;
 384                                         }
 385                                 }
 386                                 // N.B. rule of thumb: values being looked for can
 387                                 // be found only at the end of input buffer
 388                                 // this allows to get rid of strstr() and memmem()
 389
 390                                 // TODO: make expect and abort strings processed uniformly
 391                                 // abort condition is met? -> bail out
 392                                 for (l = aborts, exitcode = ERR_ABORT; l; l = l->link, ++exitcode) {
 393                                         size_t len = strlen(l->data);
 394                                         delta = buf_len-len;
 395                                         if (delta >= 0 && !memcmp(buf+delta, l->data, len))
 396                                                 goto expect_done;
 397                                 }
 398                                 exitcode = ERR_OK;
 399
 400                                 // expected reply received? -> goto next command
 401                                 delta = buf_len - expect_len;
 402                                 if (delta >= 0 && !memcmp(buf+delta, expect, expect_len))
 403                                         goto expect_done;
 404 #undef buf
 405                         } /* while (have data) */
 406
 407                         // device timed out or unexpected reply received
 408                         exitcode = ERR_TIMEOUT;
 409  expect_done:
 410 #if ENABLE_FEATURE_CHAT_NOFAIL
 411                         // on success and when in nofail mode
 412                         // we should skip following subsend-subexpect pairs
 413                         if (nofail) {
 414                                 if (!exitcode) {
 415                                         // find last send before non-dashed expect
 416                                         while (*argv && argv[1] && '-' == argv[1][0])
 417                                                 argv += 2;
 418                                         // skip the pair
 419                                         // N.B. do we really need this?!
 420                                         if (!*argv++ || !*argv++)
 421                                                 break;
 422                                 }
 423                                 // nofail mode also clears all but IO errors (or signals)
 424                                 if (ERR_IO != exitcode)
 425                                         exitcode = ERR_OK;
 426                         }
 427 #endif
 428                         // bail out unless we expected successfully
 429                         if (exitcode)
 430                                 break;
 431
 432                         //-----------------------
 433                         // do send
 434                         //-----------------------
 435                         if (*argv) {
 436 #if ENABLE_FEATURE_CHAT_IMPLICIT_CR
 437                                 int nocr = 0; // inhibit terminating command with \r
 438 #endif
 439                                 char *loaded = NULL; // loaded command
 440                                 size_t len;
 441                                 char *buf = *argv++;
 442
 443                                 // if command starts with @
 444                                 // load "real" command from file named after @
 445                                 if ('@' == *buf) {
 446                                         // skip the @ and any following white-space
 447                                         trim(++buf);
 448                                         buf = loaded = xmalloc_xopen_read_close(buf, NULL);
 449                                 }
 450                                 // expand escape sequences in command
 451                                 len = unescape(buf, &nocr);
 452
 453                                 // send command
 454                                 alarm(timeout);
 455                                 pfd.fd = STDOUT_FILENO;
 456                                 pfd.events = POLLOUT;
 457                                 while (len && !exitcode
 458                                     && poll(&pfd, 1, -1) > 0
 459                                     && (pfd.revents & POLLOUT)
 460                                 ) {
 461 #if ENABLE_FEATURE_CHAT_SEND_ESCAPES
 462                                         // "\\d" means 1 sec delay, "\\p" means 0.01 sec delay
 463                                         // "\\K" means send BREAK
 464                                         char c = *buf;
 465                                         if ('\\' == c) {
 466                                                 c = *++buf;
 467                                                 if ('d' == c) {
 468                                                         sleep(1);
 469                                                         len--;
 470                                                         continue;
 471                                                 }
 472                                                 if ('p' == c) {
 473                                                         usleep(10000);
 474                                                         len--;
 475                                                         continue;
 476                                                 }
 477                                                 if ('K' == c) {
 478                                                         tcsendbreak(STDOUT_FILENO, 0);
 479                                                         len--;
 480                                                         continue;
 481                                                 }
 482                                                 buf--;
 483                                         }
 484                                         if (safe_write(STDOUT_FILENO, buf, 1) != 1)
 485                                                 break;
 486                                         len--;
 487                                         buf++;
 488 #else
 489                                         len -= full_write(STDOUT_FILENO, buf, len);
 490 #endif
 491                                 } /* while (can write) */
 492                                 alarm(0);
 493
 494                                 // report I/O error if there still exists at least one non-sent char
 495                                 if (len)
 496                                         exitcode = ERR_IO;
 497
 498                                 // free loaded command (if any)
 499                                 if (loaded)
 500                                         free(loaded);
 501 #if ENABLE_FEATURE_CHAT_IMPLICIT_CR
 502                                 // or terminate command with \r (if not inhibited)
 503                                 else if (!nocr)
 504                                         xwrite(STDOUT_FILENO, "\r", 1);
 505 #endif
 506                                 // bail out unless we sent command successfully
 507                                 if (exitcode)
 508                                         break;
 509                         } /* if (*argv) */
 510                 }
 511         } /* while (*argv) */
 512
 513 #if ENABLE_FEATURE_CHAT_TTY_HIFI
 514         tcsetattr(STDIN_FILENO, TCSAFLUSH, &tio0);
 515 #endif
 516
 517         return exitcode;
 518 }