Contents of /trunk/mkinitrd-magellan/busybox/networking/telnetd.c
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Sun May 30 11:32:42 2010 UTC (14 years, 3 months ago) by niro
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Sun May 30 11:32:42 2010 UTC (14 years, 3 months ago) by niro
File MIME type: text/plain
File size: 19644 byte(s)
-updated to busybox-1.16.1 and enabled blkid/uuid support in default config
1 | /* vi: set sw=4 ts=4: */ |
2 | /* |
3 | * Simple telnet server |
4 | * Bjorn Wesen, Axis Communications AB (bjornw@axis.com) |
5 | * |
6 | * Licensed under GPLv2 or later, see file LICENSE in this tarball for details. |
7 | * |
8 | * --------------------------------------------------------------------------- |
9 | * (C) Copyright 2000, Axis Communications AB, LUND, SWEDEN |
10 | **************************************************************************** |
11 | * |
12 | * The telnetd manpage says it all: |
13 | * |
14 | * Telnetd operates by allocating a pseudo-terminal device (see pty(4)) for |
15 | * a client, then creating a login process which has the slave side of the |
16 | * pseudo-terminal as stdin, stdout, and stderr. Telnetd manipulates the |
17 | * master side of the pseudo-terminal, implementing the telnet protocol and |
18 | * passing characters between the remote client and the login process. |
19 | * |
20 | * Vladimir Oleynik <dzo@simtreas.ru> 2001 |
21 | * Set process group corrections, initial busybox port |
22 | */ |
23 | |
24 | #define DEBUG 0 |
25 | |
26 | #include "libbb.h" |
27 | #include <syslog.h> |
28 | |
29 | #if DEBUG |
30 | #define TELCMDS |
31 | #define TELOPTS |
32 | #endif |
33 | #include <arpa/telnet.h> |
34 | |
35 | struct tsession { |
36 | struct tsession *next; |
37 | pid_t shell_pid; |
38 | int sockfd_read; |
39 | int sockfd_write; |
40 | int ptyfd; |
41 | |
42 | /* two circular buffers */ |
43 | /*char *buf1, *buf2;*/ |
44 | /*#define TS_BUF1(ts) ts->buf1*/ |
45 | /*#define TS_BUF2(ts) TS_BUF2(ts)*/ |
46 | #define TS_BUF1(ts) ((unsigned char*)(ts + 1)) |
47 | #define TS_BUF2(ts) (((unsigned char*)(ts + 1)) + BUFSIZE) |
48 | int rdidx1, wridx1, size1; |
49 | int rdidx2, wridx2, size2; |
50 | }; |
51 | |
52 | /* Two buffers are directly after tsession in malloced memory. |
53 | * Make whole thing fit in 4k */ |
54 | enum { BUFSIZE = (4 * 1024 - sizeof(struct tsession)) / 2 }; |
55 | |
56 | |
57 | /* Globals */ |
58 | struct globals { |
59 | struct tsession *sessions; |
60 | const char *loginpath; |
61 | const char *issuefile; |
62 | int maxfd; |
63 | }; |
64 | #define G (*(struct globals*)&bb_common_bufsiz1) |
65 | #define INIT_G() do { \ |
66 | G.loginpath = "/bin/login"; \ |
67 | G.issuefile = "/etc/issue.net"; \ |
68 | } while (0) |
69 | |
70 | |
71 | /* |
72 | Remove all IAC's from buf1 (received IACs are ignored and must be removed |
73 | so as to not be interpreted by the terminal). Make an uninterrupted |
74 | string of characters fit for the terminal. Do this by packing |
75 | all characters meant for the terminal sequentially towards the end of buf. |
76 | |
77 | Return a pointer to the beginning of the characters meant for the terminal. |
78 | and make *num_totty the number of characters that should be sent to |
79 | the terminal. |
80 | |
81 | Note - If an IAC (3 byte quantity) starts before (bf + len) but extends |
82 | past (bf + len) then that IAC will be left unprocessed and *processed |
83 | will be less than len. |
84 | |
85 | CR-LF ->'s CR mapping is also done here, for convenience. |
86 | |
87 | NB: may fail to remove iacs which wrap around buffer! |
88 | */ |
89 | static unsigned char * |
90 | remove_iacs(struct tsession *ts, int *pnum_totty) |
91 | { |
92 | unsigned char *ptr0 = TS_BUF1(ts) + ts->wridx1; |
93 | unsigned char *ptr = ptr0; |
94 | unsigned char *totty = ptr; |
95 | unsigned char *end = ptr + MIN(BUFSIZE - ts->wridx1, ts->size1); |
96 | int num_totty; |
97 | |
98 | while (ptr < end) { |
99 | if (*ptr != IAC) { |
100 | char c = *ptr; |
101 | |
102 | *totty++ = c; |
103 | ptr++; |
104 | /* We map \r\n ==> \r for pragmatic reasons. |
105 | * Many client implementations send \r\n when |
106 | * the user hits the CarriageReturn key. |
107 | */ |
108 | if (c == '\r' && ptr < end && (*ptr == '\n' || *ptr == '\0')) |
109 | ptr++; |
110 | continue; |
111 | } |
112 | |
113 | if ((ptr+1) >= end) |
114 | break; |
115 | if (ptr[1] == NOP) { /* Ignore? (putty keepalive, etc.) */ |
116 | ptr += 2; |
117 | continue; |
118 | } |
119 | if (ptr[1] == IAC) { /* Literal IAC? (emacs M-DEL) */ |
120 | *totty++ = ptr[1]; |
121 | ptr += 2; |
122 | continue; |
123 | } |
124 | |
125 | /* |
126 | * TELOPT_NAWS support! |
127 | */ |
128 | if ((ptr+2) >= end) { |
129 | /* Only the beginning of the IAC is in the |
130 | buffer we were asked to process, we can't |
131 | process this char */ |
132 | break; |
133 | } |
134 | /* |
135 | * IAC -> SB -> TELOPT_NAWS -> 4-byte -> IAC -> SE |
136 | */ |
137 | if (ptr[1] == SB && ptr[2] == TELOPT_NAWS) { |
138 | struct winsize ws; |
139 | if ((ptr+8) >= end) |
140 | break; /* incomplete, can't process */ |
141 | ws.ws_col = (ptr[3] << 8) | ptr[4]; |
142 | ws.ws_row = (ptr[5] << 8) | ptr[6]; |
143 | ioctl(ts->ptyfd, TIOCSWINSZ, (char *)&ws); |
144 | ptr += 9; |
145 | continue; |
146 | } |
147 | /* skip 3-byte IAC non-SB cmd */ |
148 | #if DEBUG |
149 | fprintf(stderr, "Ignoring IAC %s,%s\n", |
150 | TELCMD(ptr[1]), TELOPT(ptr[2])); |
151 | #endif |
152 | ptr += 3; |
153 | } |
154 | |
155 | num_totty = totty - ptr0; |
156 | *pnum_totty = num_totty; |
157 | /* The difference between ptr and totty is number of iacs |
158 | we removed from the stream. Adjust buf1 accordingly */ |
159 | if ((ptr - totty) == 0) /* 99.999% of cases */ |
160 | return ptr0; |
161 | ts->wridx1 += ptr - totty; |
162 | ts->size1 -= ptr - totty; |
163 | /* Move chars meant for the terminal towards the end of the buffer */ |
164 | return memmove(ptr - num_totty, ptr0, num_totty); |
165 | } |
166 | |
167 | /* |
168 | * Converting single IAC into double on output |
169 | */ |
170 | static size_t iac_safe_write(int fd, const char *buf, size_t count) |
171 | { |
172 | const char *IACptr; |
173 | size_t wr, rc, total; |
174 | |
175 | total = 0; |
176 | while (1) { |
177 | if (count == 0) |
178 | return total; |
179 | if (*buf == (char)IAC) { |
180 | static const char IACIAC[] ALIGN1 = { IAC, IAC }; |
181 | rc = safe_write(fd, IACIAC, 2); |
182 | if (rc != 2) |
183 | break; |
184 | buf++; |
185 | total++; |
186 | count--; |
187 | continue; |
188 | } |
189 | /* count != 0, *buf != IAC */ |
190 | IACptr = memchr(buf, IAC, count); |
191 | wr = count; |
192 | if (IACptr) |
193 | wr = IACptr - buf; |
194 | rc = safe_write(fd, buf, wr); |
195 | if (rc != wr) |
196 | break; |
197 | buf += rc; |
198 | total += rc; |
199 | count -= rc; |
200 | } |
201 | /* here: rc - result of last short write */ |
202 | if ((ssize_t)rc < 0) { /* error? */ |
203 | if (total == 0) |
204 | return rc; |
205 | rc = 0; |
206 | } |
207 | return total + rc; |
208 | } |
209 | |
210 | /* Must match getopt32 string */ |
211 | enum { |
212 | OPT_WATCHCHILD = (1 << 2), /* -K */ |
213 | OPT_INETD = (1 << 3) * ENABLE_FEATURE_TELNETD_STANDALONE, /* -i */ |
214 | OPT_PORT = (1 << 4) * ENABLE_FEATURE_TELNETD_STANDALONE, /* -p PORT */ |
215 | OPT_FOREGROUND = (1 << 6) * ENABLE_FEATURE_TELNETD_STANDALONE, /* -F */ |
216 | OPT_SYSLOG = (1 << 7) * ENABLE_FEATURE_TELNETD_INETD_WAIT, /* -S */ |
217 | OPT_WAIT = (1 << 8) * ENABLE_FEATURE_TELNETD_INETD_WAIT, /* -w SEC */ |
218 | }; |
219 | |
220 | static struct tsession * |
221 | make_new_session( |
222 | IF_FEATURE_TELNETD_STANDALONE(int sock) |
223 | IF_NOT_FEATURE_TELNETD_STANDALONE(void) |
224 | ) { |
225 | const char *login_argv[2]; |
226 | struct termios termbuf; |
227 | int fd, pid; |
228 | char tty_name[GETPTY_BUFSIZE]; |
229 | struct tsession *ts = xzalloc(sizeof(struct tsession) + BUFSIZE * 2); |
230 | |
231 | /*ts->buf1 = (char *)(ts + 1);*/ |
232 | /*ts->buf2 = ts->buf1 + BUFSIZE;*/ |
233 | |
234 | /* Got a new connection, set up a tty */ |
235 | fd = xgetpty(tty_name); |
236 | if (fd > G.maxfd) |
237 | G.maxfd = fd; |
238 | ts->ptyfd = fd; |
239 | ndelay_on(fd); |
240 | close_on_exec_on(fd); |
241 | |
242 | #if ENABLE_FEATURE_TELNETD_STANDALONE |
243 | /* SO_KEEPALIVE by popular demand */ |
244 | setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, &const_int_1, sizeof(const_int_1)); |
245 | ts->sockfd_read = sock; |
246 | ndelay_on(sock); |
247 | if (sock == 0) { /* We are called with fd 0 - we are in inetd mode */ |
248 | sock++; /* so use fd 1 for output */ |
249 | ndelay_on(sock); |
250 | } |
251 | ts->sockfd_write = sock; |
252 | if (sock > G.maxfd) |
253 | G.maxfd = sock; |
254 | #else |
255 | /* SO_KEEPALIVE by popular demand */ |
256 | setsockopt(0, SOL_SOCKET, SO_KEEPALIVE, &const_int_1, sizeof(const_int_1)); |
257 | /* ts->sockfd_read = 0; - done by xzalloc */ |
258 | ts->sockfd_write = 1; |
259 | ndelay_on(0); |
260 | ndelay_on(1); |
261 | #endif |
262 | |
263 | /* Make the telnet client understand we will echo characters so it |
264 | * should not do it locally. We don't tell the client to run linemode, |
265 | * because we want to handle line editing and tab completion and other |
266 | * stuff that requires char-by-char support. */ |
267 | { |
268 | static const char iacs_to_send[] ALIGN1 = { |
269 | IAC, DO, TELOPT_ECHO, |
270 | IAC, DO, TELOPT_NAWS, |
271 | /* This requires telnetd.ctrlSQ.patch (incomplete) */ |
272 | /* IAC, DO, TELOPT_LFLOW, */ |
273 | IAC, WILL, TELOPT_ECHO, |
274 | IAC, WILL, TELOPT_SGA |
275 | }; |
276 | /* This confuses iac_safe_write(), it will try to duplicate |
277 | * each IAC... */ |
278 | //memcpy(TS_BUF2(ts), iacs_to_send, sizeof(iacs_to_send)); |
279 | //ts->rdidx2 = sizeof(iacs_to_send); |
280 | //ts->size2 = sizeof(iacs_to_send); |
281 | /* So just stuff it into TCP stream! (no error check...) */ |
282 | #if ENABLE_FEATURE_TELNETD_STANDALONE |
283 | safe_write(sock, iacs_to_send, sizeof(iacs_to_send)); |
284 | #else |
285 | safe_write(1, iacs_to_send, sizeof(iacs_to_send)); |
286 | #endif |
287 | /*ts->rdidx2 = 0; - xzalloc did it */ |
288 | /*ts->size2 = 0;*/ |
289 | } |
290 | |
291 | fflush_all(); |
292 | pid = vfork(); /* NOMMU-friendly */ |
293 | if (pid < 0) { |
294 | free(ts); |
295 | close(fd); |
296 | /* sock will be closed by caller */ |
297 | bb_perror_msg("vfork"); |
298 | return NULL; |
299 | } |
300 | if (pid > 0) { |
301 | /* Parent */ |
302 | ts->shell_pid = pid; |
303 | return ts; |
304 | } |
305 | |
306 | /* Child */ |
307 | /* Careful - we are after vfork! */ |
308 | |
309 | /* Restore default signal handling ASAP */ |
310 | bb_signals((1 << SIGCHLD) + (1 << SIGPIPE), SIG_DFL); |
311 | |
312 | /* Make new session and process group */ |
313 | setsid(); |
314 | |
315 | /* Open the child's side of the tty */ |
316 | /* NB: setsid() disconnects from any previous ctty's. Therefore |
317 | * we must open child's side of the tty AFTER setsid! */ |
318 | close(0); |
319 | xopen(tty_name, O_RDWR); /* becomes our ctty */ |
320 | xdup2(0, 1); |
321 | xdup2(0, 2); |
322 | tcsetpgrp(0, getpid()); /* switch this tty's process group to us */ |
323 | |
324 | /* The pseudo-terminal allocated to the client is configured to operate |
325 | * in cooked mode, and with XTABS CRMOD enabled (see tty(4)) */ |
326 | tcgetattr(0, &termbuf); |
327 | termbuf.c_lflag |= ECHO; /* if we use readline we dont want this */ |
328 | termbuf.c_oflag |= ONLCR | XTABS; |
329 | termbuf.c_iflag |= ICRNL; |
330 | termbuf.c_iflag &= ~IXOFF; |
331 | /*termbuf.c_lflag &= ~ICANON;*/ |
332 | tcsetattr_stdin_TCSANOW(&termbuf); |
333 | |
334 | /* Uses FILE-based I/O to stdout, but does fflush_all(), |
335 | * so should be safe with vfork. |
336 | * I fear, though, that some users will have ridiculously big |
337 | * issue files, and they may block writing to fd 1, |
338 | * (parent is supposed to read it, but parent waits |
339 | * for vforked child to exec!) */ |
340 | print_login_issue(G.issuefile, tty_name); |
341 | |
342 | /* Exec shell / login / whatever */ |
343 | login_argv[0] = G.loginpath; |
344 | login_argv[1] = NULL; |
345 | /* exec busybox applet (if PREFER_APPLETS=y), if that fails, |
346 | * exec external program. |
347 | * NB: sock is either 0 or has CLOEXEC set on it. |
348 | * fd has CLOEXEC set on it too. These two fds will be closed here. |
349 | */ |
350 | BB_EXECVP(G.loginpath, (char **)login_argv); |
351 | /* _exit is safer with vfork, and we shouldn't send message |
352 | * to remote clients anyway */ |
353 | _exit(EXIT_FAILURE); /*bb_perror_msg_and_die("execv %s", G.loginpath);*/ |
354 | } |
355 | |
356 | #if ENABLE_FEATURE_TELNETD_STANDALONE |
357 | |
358 | static void |
359 | free_session(struct tsession *ts) |
360 | { |
361 | struct tsession *t = G.sessions; |
362 | |
363 | if (option_mask32 & OPT_INETD) |
364 | exit(EXIT_SUCCESS); |
365 | |
366 | /* Unlink this telnet session from the session list */ |
367 | if (t == ts) |
368 | G.sessions = ts->next; |
369 | else { |
370 | while (t->next != ts) |
371 | t = t->next; |
372 | t->next = ts->next; |
373 | } |
374 | |
375 | #if 0 |
376 | /* It was said that "normal" telnetd just closes ptyfd, |
377 | * doesn't send SIGKILL. When we close ptyfd, |
378 | * kernel sends SIGHUP to processes having slave side opened. */ |
379 | kill(ts->shell_pid, SIGKILL); |
380 | waitpid(ts->shell_pid, NULL, 0); |
381 | #endif |
382 | close(ts->ptyfd); |
383 | close(ts->sockfd_read); |
384 | /* We do not need to close(ts->sockfd_write), it's the same |
385 | * as sockfd_read unless we are in inetd mode. But in inetd mode |
386 | * we do not reach this */ |
387 | free(ts); |
388 | |
389 | /* Scan all sessions and find new maxfd */ |
390 | G.maxfd = 0; |
391 | ts = G.sessions; |
392 | while (ts) { |
393 | if (G.maxfd < ts->ptyfd) |
394 | G.maxfd = ts->ptyfd; |
395 | if (G.maxfd < ts->sockfd_read) |
396 | G.maxfd = ts->sockfd_read; |
397 | #if 0 |
398 | /* Again, sockfd_write == sockfd_read here */ |
399 | if (G.maxfd < ts->sockfd_write) |
400 | G.maxfd = ts->sockfd_write; |
401 | #endif |
402 | ts = ts->next; |
403 | } |
404 | } |
405 | |
406 | #else /* !FEATURE_TELNETD_STANDALONE */ |
407 | |
408 | /* Used in main() only, thus "return 0" actually is exit(EXIT_SUCCESS). */ |
409 | #define free_session(ts) return 0 |
410 | |
411 | #endif |
412 | |
413 | static void handle_sigchld(int sig UNUSED_PARAM) |
414 | { |
415 | pid_t pid; |
416 | struct tsession *ts; |
417 | |
418 | /* Looping: more than one child may have exited */ |
419 | while (1) { |
420 | pid = wait_any_nohang(NULL); |
421 | if (pid <= 0) |
422 | break; |
423 | ts = G.sessions; |
424 | while (ts) { |
425 | if (ts->shell_pid == pid) { |
426 | ts->shell_pid = -1; |
427 | break; |
428 | } |
429 | ts = ts->next; |
430 | } |
431 | } |
432 | } |
433 | |
434 | int telnetd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
435 | int telnetd_main(int argc UNUSED_PARAM, char **argv) |
436 | { |
437 | fd_set rdfdset, wrfdset; |
438 | unsigned opt; |
439 | int count; |
440 | struct tsession *ts; |
441 | #if ENABLE_FEATURE_TELNETD_STANDALONE |
442 | #define IS_INETD (opt & OPT_INETD) |
443 | int master_fd = master_fd; /* for compiler */ |
444 | int sec_linger = sec_linger; |
445 | char *opt_bindaddr = NULL; |
446 | char *opt_portnbr; |
447 | #else |
448 | enum { |
449 | IS_INETD = 1, |
450 | master_fd = -1, |
451 | }; |
452 | #endif |
453 | INIT_G(); |
454 | |
455 | /* -w NUM, and implies -F. -w and -i don't mix */ |
456 | IF_FEATURE_TELNETD_INETD_WAIT(opt_complementary = "wF:w+:i--w:w--i";) |
457 | /* Even if !STANDALONE, we accept (and ignore) -i, thus people |
458 | * don't need to guess whether it's ok to pass -i to us */ |
459 | opt = getopt32(argv, "f:l:Ki" |
460 | IF_FEATURE_TELNETD_STANDALONE("p:b:F") |
461 | IF_FEATURE_TELNETD_INETD_WAIT("Sw:"), |
462 | &G.issuefile, &G.loginpath |
463 | IF_FEATURE_TELNETD_STANDALONE(, &opt_portnbr, &opt_bindaddr) |
464 | IF_FEATURE_TELNETD_INETD_WAIT(, &sec_linger) |
465 | ); |
466 | if (!IS_INETD /*&& !re_execed*/) { |
467 | /* inform that we start in standalone mode? |
468 | * May be useful when people forget to give -i */ |
469 | /*bb_error_msg("listening for connections");*/ |
470 | if (!(opt & OPT_FOREGROUND)) { |
471 | /* DAEMON_CHDIR_ROOT was giving inconsistent |
472 | * behavior with/without -F, -i */ |
473 | bb_daemonize_or_rexec(0 /*was DAEMON_CHDIR_ROOT*/, argv); |
474 | } |
475 | } |
476 | /* Redirect log to syslog early, if needed */ |
477 | if (IS_INETD || (opt & OPT_SYSLOG) || !(opt & OPT_FOREGROUND)) { |
478 | openlog(applet_name, LOG_PID, LOG_DAEMON); |
479 | logmode = LOGMODE_SYSLOG; |
480 | } |
481 | #if ENABLE_FEATURE_TELNETD_STANDALONE |
482 | if (IS_INETD) { |
483 | G.sessions = make_new_session(0); |
484 | if (!G.sessions) /* pty opening or vfork problem, exit */ |
485 | return 1; /* make_new_session printed error message */ |
486 | } else { |
487 | master_fd = 0; |
488 | if (!(opt & OPT_WAIT)) { |
489 | unsigned portnbr = 23; |
490 | if (opt & OPT_PORT) |
491 | portnbr = xatou16(opt_portnbr); |
492 | master_fd = create_and_bind_stream_or_die(opt_bindaddr, portnbr); |
493 | xlisten(master_fd, 1); |
494 | } |
495 | close_on_exec_on(master_fd); |
496 | } |
497 | #else |
498 | G.sessions = make_new_session(); |
499 | if (!G.sessions) /* pty opening or vfork problem, exit */ |
500 | return 1; /* make_new_session printed error message */ |
501 | #endif |
502 | |
503 | /* We don't want to die if just one session is broken */ |
504 | signal(SIGPIPE, SIG_IGN); |
505 | |
506 | if (opt & OPT_WATCHCHILD) |
507 | signal(SIGCHLD, handle_sigchld); |
508 | else /* prevent dead children from becoming zombies */ |
509 | signal(SIGCHLD, SIG_IGN); |
510 | |
511 | /* |
512 | This is how the buffers are used. The arrows indicate data flow. |
513 | |
514 | +-------+ wridx1++ +------+ rdidx1++ +----------+ |
515 | | | <-------------- | buf1 | <-------------- | | |
516 | | | size1-- +------+ size1++ | | |
517 | | pty | | socket | |
518 | | | rdidx2++ +------+ wridx2++ | | |
519 | | | --------------> | buf2 | --------------> | | |
520 | +-------+ size2++ +------+ size2-- +----------+ |
521 | |
522 | size1: "how many bytes are buffered for pty between rdidx1 and wridx1?" |
523 | size2: "how many bytes are buffered for socket between rdidx2 and wridx2?" |
524 | |
525 | Each session has got two buffers. Buffers are circular. If sizeN == 0, |
526 | buffer is empty. If sizeN == BUFSIZE, buffer is full. In both these cases |
527 | rdidxN == wridxN. |
528 | */ |
529 | again: |
530 | FD_ZERO(&rdfdset); |
531 | FD_ZERO(&wrfdset); |
532 | |
533 | /* Select on the master socket, all telnet sockets and their |
534 | * ptys if there is room in their session buffers. |
535 | * NB: scalability problem: we recalculate entire bitmap |
536 | * before each select. Can be a problem with 500+ connections. */ |
537 | ts = G.sessions; |
538 | while (ts) { |
539 | struct tsession *next = ts->next; /* in case we free ts */ |
540 | if (ts->shell_pid == -1) { |
541 | /* Child died and we detected that */ |
542 | free_session(ts); |
543 | } else { |
544 | if (ts->size1 > 0) /* can write to pty */ |
545 | FD_SET(ts->ptyfd, &wrfdset); |
546 | if (ts->size1 < BUFSIZE) /* can read from socket */ |
547 | FD_SET(ts->sockfd_read, &rdfdset); |
548 | if (ts->size2 > 0) /* can write to socket */ |
549 | FD_SET(ts->sockfd_write, &wrfdset); |
550 | if (ts->size2 < BUFSIZE) /* can read from pty */ |
551 | FD_SET(ts->ptyfd, &rdfdset); |
552 | } |
553 | ts = next; |
554 | } |
555 | if (!IS_INETD) { |
556 | FD_SET(master_fd, &rdfdset); |
557 | /* This is needed because free_session() does not |
558 | * take master_fd into account when it finds new |
559 | * maxfd among remaining fd's */ |
560 | if (master_fd > G.maxfd) |
561 | G.maxfd = master_fd; |
562 | } |
563 | |
564 | { |
565 | struct timeval *tv_ptr = NULL; |
566 | #if ENABLE_FEATURE_TELNETD_INETD_WAIT |
567 | struct timeval tv; |
568 | if ((opt & OPT_WAIT) && !G.sessions) { |
569 | tv.tv_sec = sec_linger; |
570 | tv.tv_usec = 0; |
571 | tv_ptr = &tv; |
572 | } |
573 | #endif |
574 | count = select(G.maxfd + 1, &rdfdset, &wrfdset, NULL, tv_ptr); |
575 | } |
576 | if (count == 0) /* "telnetd -w SEC" timed out */ |
577 | return 0; |
578 | if (count < 0) |
579 | goto again; /* EINTR or ENOMEM */ |
580 | |
581 | #if ENABLE_FEATURE_TELNETD_STANDALONE |
582 | /* Check for and accept new sessions */ |
583 | if (!IS_INETD && FD_ISSET(master_fd, &rdfdset)) { |
584 | int fd; |
585 | struct tsession *new_ts; |
586 | |
587 | fd = accept(master_fd, NULL, NULL); |
588 | if (fd < 0) |
589 | goto again; |
590 | close_on_exec_on(fd); |
591 | |
592 | /* Create a new session and link it into active list */ |
593 | new_ts = make_new_session(fd); |
594 | if (new_ts) { |
595 | new_ts->next = G.sessions; |
596 | G.sessions = new_ts; |
597 | } else { |
598 | close(fd); |
599 | } |
600 | } |
601 | #endif |
602 | |
603 | /* Then check for data tunneling */ |
604 | ts = G.sessions; |
605 | while (ts) { /* For all sessions... */ |
606 | struct tsession *next = ts->next; /* in case we free ts */ |
607 | |
608 | if (/*ts->size1 &&*/ FD_ISSET(ts->ptyfd, &wrfdset)) { |
609 | int num_totty; |
610 | unsigned char *ptr; |
611 | /* Write to pty from buffer 1 */ |
612 | ptr = remove_iacs(ts, &num_totty); |
613 | count = safe_write(ts->ptyfd, ptr, num_totty); |
614 | if (count < 0) { |
615 | if (errno == EAGAIN) |
616 | goto skip1; |
617 | goto kill_session; |
618 | } |
619 | ts->size1 -= count; |
620 | ts->wridx1 += count; |
621 | if (ts->wridx1 >= BUFSIZE) /* actually == BUFSIZE */ |
622 | ts->wridx1 = 0; |
623 | } |
624 | skip1: |
625 | if (/*ts->size2 &&*/ FD_ISSET(ts->sockfd_write, &wrfdset)) { |
626 | /* Write to socket from buffer 2 */ |
627 | count = MIN(BUFSIZE - ts->wridx2, ts->size2); |
628 | count = iac_safe_write(ts->sockfd_write, (void*)(TS_BUF2(ts) + ts->wridx2), count); |
629 | if (count < 0) { |
630 | if (errno == EAGAIN) |
631 | goto skip2; |
632 | goto kill_session; |
633 | } |
634 | ts->size2 -= count; |
635 | ts->wridx2 += count; |
636 | if (ts->wridx2 >= BUFSIZE) /* actually == BUFSIZE */ |
637 | ts->wridx2 = 0; |
638 | } |
639 | skip2: |
640 | /* Should not be needed, but... remove_iacs is actually buggy |
641 | * (it cannot process iacs which wrap around buffer's end)! |
642 | * Since properly fixing it requires writing bigger code, |
643 | * we rely instead on this code making it virtually impossible |
644 | * to have wrapped iac (people don't type at 2k/second). |
645 | * It also allows for bigger reads in common case. */ |
646 | if (ts->size1 == 0) { |
647 | ts->rdidx1 = 0; |
648 | ts->wridx1 = 0; |
649 | } |
650 | if (ts->size2 == 0) { |
651 | ts->rdidx2 = 0; |
652 | ts->wridx2 = 0; |
653 | } |
654 | |
655 | if (/*ts->size1 < BUFSIZE &&*/ FD_ISSET(ts->sockfd_read, &rdfdset)) { |
656 | /* Read from socket to buffer 1 */ |
657 | count = MIN(BUFSIZE - ts->rdidx1, BUFSIZE - ts->size1); |
658 | count = safe_read(ts->sockfd_read, TS_BUF1(ts) + ts->rdidx1, count); |
659 | if (count <= 0) { |
660 | if (count < 0 && errno == EAGAIN) |
661 | goto skip3; |
662 | goto kill_session; |
663 | } |
664 | /* Ignore trailing NUL if it is there */ |
665 | if (!TS_BUF1(ts)[ts->rdidx1 + count - 1]) { |
666 | --count; |
667 | } |
668 | ts->size1 += count; |
669 | ts->rdidx1 += count; |
670 | if (ts->rdidx1 >= BUFSIZE) /* actually == BUFSIZE */ |
671 | ts->rdidx1 = 0; |
672 | } |
673 | skip3: |
674 | if (/*ts->size2 < BUFSIZE &&*/ FD_ISSET(ts->ptyfd, &rdfdset)) { |
675 | /* Read from pty to buffer 2 */ |
676 | count = MIN(BUFSIZE - ts->rdidx2, BUFSIZE - ts->size2); |
677 | count = safe_read(ts->ptyfd, TS_BUF2(ts) + ts->rdidx2, count); |
678 | if (count <= 0) { |
679 | if (count < 0 && errno == EAGAIN) |
680 | goto skip4; |
681 | goto kill_session; |
682 | } |
683 | ts->size2 += count; |
684 | ts->rdidx2 += count; |
685 | if (ts->rdidx2 >= BUFSIZE) /* actually == BUFSIZE */ |
686 | ts->rdidx2 = 0; |
687 | } |
688 | skip4: |
689 | ts = next; |
690 | continue; |
691 | kill_session: |
692 | free_session(ts); |
693 | ts = next; |
694 | } |
695 | |
696 | goto again; |
697 | } |