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