Annotation of /tags/mkinitrd-6_3_1/busybox/networking/telnetd.c
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Thu Aug 19 12:44:27 2010 UTC (13 years, 10 months ago) by niro
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Thu Aug 19 12:44:27 2010 UTC (13 years, 10 months ago) by niro
File MIME type: text/plain
File size: 20641 byte(s)
tagged 'mkinitrd-6_3_1'
1 | niro | 532 | /* 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 | niro | 984 | * 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 | niro | 532 | * |
20 | * Vladimir Oleynik <dzo@simtreas.ru> 2001 | ||
21 | niro | 984 | * Set process group corrections, initial busybox port |
22 | niro | 532 | */ |
23 | #define DEBUG 0 | ||
24 | |||
25 | niro | 816 | #include "libbb.h" |
26 | #include <syslog.h> | ||
27 | niro | 532 | |
28 | #if DEBUG | ||
29 | niro | 1123 | # define TELCMDS |
30 | # define TELOPTS | ||
31 | niro | 532 | #endif |
32 | #include <arpa/telnet.h> | ||
33 | |||
34 | niro | 1123 | #if ENABLE_FEATURE_UTMP |
35 | # include <utmp.h> /* LOGIN_PROCESS */ | ||
36 | #endif | ||
37 | |||
38 | |||
39 | niro | 532 | struct tsession { |
40 | struct tsession *next; | ||
41 | niro | 984 | pid_t shell_pid; |
42 | int sockfd_read; | ||
43 | int sockfd_write; | ||
44 | int ptyfd; | ||
45 | niro | 816 | |
46 | niro | 532 | /* two circular buffers */ |
47 | niro | 816 | /*char *buf1, *buf2;*/ |
48 | niro | 984 | /*#define TS_BUF1(ts) ts->buf1*/ |
49 | /*#define TS_BUF2(ts) TS_BUF2(ts)*/ | ||
50 | #define TS_BUF1(ts) ((unsigned char*)(ts + 1)) | ||
51 | #define TS_BUF2(ts) (((unsigned char*)(ts + 1)) + BUFSIZE) | ||
52 | niro | 532 | int rdidx1, wridx1, size1; |
53 | int rdidx2, wridx2, size2; | ||
54 | }; | ||
55 | |||
56 | niro | 816 | /* Two buffers are directly after tsession in malloced memory. |
57 | * Make whole thing fit in 4k */ | ||
58 | enum { BUFSIZE = (4 * 1024 - sizeof(struct tsession)) / 2 }; | ||
59 | niro | 532 | |
60 | |||
61 | niro | 816 | /* Globals */ |
62 | niro | 984 | struct globals { |
63 | struct tsession *sessions; | ||
64 | const char *loginpath; | ||
65 | const char *issuefile; | ||
66 | int maxfd; | ||
67 | niro | 1123 | } FIX_ALIASING; |
68 | niro | 984 | #define G (*(struct globals*)&bb_common_bufsiz1) |
69 | #define INIT_G() do { \ | ||
70 | G.loginpath = "/bin/login"; \ | ||
71 | G.issuefile = "/etc/issue.net"; \ | ||
72 | } while (0) | ||
73 | niro | 532 | |
74 | |||
75 | /* | ||
76 | niro | 816 | Remove all IAC's from buf1 (received IACs are ignored and must be removed |
77 | so as to not be interpreted by the terminal). Make an uninterrupted | ||
78 | string of characters fit for the terminal. Do this by packing | ||
79 | all characters meant for the terminal sequentially towards the end of buf. | ||
80 | niro | 532 | |
81 | niro | 1123 | Return a pointer to the beginning of the characters meant for the terminal |
82 | niro | 532 | and make *num_totty the number of characters that should be sent to |
83 | the terminal. | ||
84 | |||
85 | niro | 1123 | Note - if an IAC (3 byte quantity) starts before (bf + len) but extends |
86 | niro | 816 | past (bf + len) then that IAC will be left unprocessed and *processed |
87 | will be less than len. | ||
88 | niro | 532 | |
89 | niro | 816 | CR-LF ->'s CR mapping is also done here, for convenience. |
90 | |||
91 | NB: may fail to remove iacs which wrap around buffer! | ||
92 | niro | 532 | */ |
93 | niro | 816 | static unsigned char * |
94 | niro | 532 | remove_iacs(struct tsession *ts, int *pnum_totty) |
95 | { | ||
96 | niro | 984 | unsigned char *ptr0 = TS_BUF1(ts) + ts->wridx1; |
97 | niro | 532 | unsigned char *ptr = ptr0; |
98 | unsigned char *totty = ptr; | ||
99 | unsigned char *end = ptr + MIN(BUFSIZE - ts->wridx1, ts->size1); | ||
100 | int num_totty; | ||
101 | |||
102 | while (ptr < end) { | ||
103 | if (*ptr != IAC) { | ||
104 | niro | 816 | char c = *ptr; |
105 | |||
106 | *totty++ = c; | ||
107 | ptr++; | ||
108 | /* We map \r\n ==> \r for pragmatic reasons. | ||
109 | niro | 532 | * Many client implementations send \r\n when |
110 | * the user hits the CarriageReturn key. | ||
111 | */ | ||
112 | niro | 816 | if (c == '\r' && ptr < end && (*ptr == '\n' || *ptr == '\0')) |
113 | niro | 532 | ptr++; |
114 | niro | 816 | continue; |
115 | } | ||
116 | niro | 532 | |
117 | niro | 816 | if ((ptr+1) >= end) |
118 | break; | ||
119 | if (ptr[1] == NOP) { /* Ignore? (putty keepalive, etc.) */ | ||
120 | ptr += 2; | ||
121 | continue; | ||
122 | } | ||
123 | if (ptr[1] == IAC) { /* Literal IAC? (emacs M-DEL) */ | ||
124 | *totty++ = ptr[1]; | ||
125 | ptr += 2; | ||
126 | continue; | ||
127 | } | ||
128 | |||
129 | /* | ||
130 | * TELOPT_NAWS support! | ||
131 | */ | ||
132 | if ((ptr+2) >= end) { | ||
133 | niro | 984 | /* Only the beginning of the IAC is in the |
134 | niro | 816 | buffer we were asked to process, we can't |
135 | niro | 984 | process this char */ |
136 | niro | 816 | break; |
137 | } | ||
138 | /* | ||
139 | * IAC -> SB -> TELOPT_NAWS -> 4-byte -> IAC -> SE | ||
140 | */ | ||
141 | if (ptr[1] == SB && ptr[2] == TELOPT_NAWS) { | ||
142 | struct winsize ws; | ||
143 | if ((ptr+8) >= end) | ||
144 | break; /* incomplete, can't process */ | ||
145 | ws.ws_col = (ptr[3] << 8) | ptr[4]; | ||
146 | ws.ws_row = (ptr[5] << 8) | ptr[6]; | ||
147 | ioctl(ts->ptyfd, TIOCSWINSZ, (char *)&ws); | ||
148 | ptr += 9; | ||
149 | continue; | ||
150 | } | ||
151 | /* skip 3-byte IAC non-SB cmd */ | ||
152 | niro | 532 | #if DEBUG |
153 | niro | 816 | fprintf(stderr, "Ignoring IAC %s,%s\n", |
154 | TELCMD(ptr[1]), TELOPT(ptr[2])); | ||
155 | niro | 532 | #endif |
156 | niro | 816 | ptr += 3; |
157 | niro | 532 | } |
158 | |||
159 | num_totty = totty - ptr0; | ||
160 | *pnum_totty = num_totty; | ||
161 | niro | 984 | /* The difference between ptr and totty is number of iacs |
162 | we removed from the stream. Adjust buf1 accordingly */ | ||
163 | niro | 816 | if ((ptr - totty) == 0) /* 99.999% of cases */ |
164 | return ptr0; | ||
165 | ts->wridx1 += ptr - totty; | ||
166 | ts->size1 -= ptr - totty; | ||
167 | niro | 984 | /* Move chars meant for the terminal towards the end of the buffer */ |
168 | niro | 532 | return memmove(ptr - num_totty, ptr0, num_totty); |
169 | } | ||
170 | |||
171 | niro | 984 | /* |
172 | * Converting single IAC into double on output | ||
173 | */ | ||
174 | static size_t iac_safe_write(int fd, const char *buf, size_t count) | ||
175 | { | ||
176 | const char *IACptr; | ||
177 | size_t wr, rc, total; | ||
178 | niro | 532 | |
179 | niro | 984 | total = 0; |
180 | while (1) { | ||
181 | if (count == 0) | ||
182 | return total; | ||
183 | if (*buf == (char)IAC) { | ||
184 | static const char IACIAC[] ALIGN1 = { IAC, IAC }; | ||
185 | rc = safe_write(fd, IACIAC, 2); | ||
186 | if (rc != 2) | ||
187 | break; | ||
188 | buf++; | ||
189 | total++; | ||
190 | count--; | ||
191 | continue; | ||
192 | } | ||
193 | /* count != 0, *buf != IAC */ | ||
194 | IACptr = memchr(buf, IAC, count); | ||
195 | wr = count; | ||
196 | if (IACptr) | ||
197 | wr = IACptr - buf; | ||
198 | rc = safe_write(fd, buf, wr); | ||
199 | if (rc != wr) | ||
200 | break; | ||
201 | buf += rc; | ||
202 | total += rc; | ||
203 | count -= rc; | ||
204 | } | ||
205 | /* here: rc - result of last short write */ | ||
206 | if ((ssize_t)rc < 0) { /* error? */ | ||
207 | if (total == 0) | ||
208 | return rc; | ||
209 | rc = 0; | ||
210 | } | ||
211 | return total + rc; | ||
212 | } | ||
213 | |||
214 | /* Must match getopt32 string */ | ||
215 | enum { | ||
216 | OPT_WATCHCHILD = (1 << 2), /* -K */ | ||
217 | OPT_INETD = (1 << 3) * ENABLE_FEATURE_TELNETD_STANDALONE, /* -i */ | ||
218 | OPT_PORT = (1 << 4) * ENABLE_FEATURE_TELNETD_STANDALONE, /* -p PORT */ | ||
219 | OPT_FOREGROUND = (1 << 6) * ENABLE_FEATURE_TELNETD_STANDALONE, /* -F */ | ||
220 | OPT_SYSLOG = (1 << 7) * ENABLE_FEATURE_TELNETD_INETD_WAIT, /* -S */ | ||
221 | OPT_WAIT = (1 << 8) * ENABLE_FEATURE_TELNETD_INETD_WAIT, /* -w SEC */ | ||
222 | }; | ||
223 | |||
224 | niro | 532 | static struct tsession * |
225 | make_new_session( | ||
226 | niro | 984 | IF_FEATURE_TELNETD_STANDALONE(int sock) |
227 | IF_NOT_FEATURE_TELNETD_STANDALONE(void) | ||
228 | niro | 532 | ) { |
229 | niro | 1123 | #if !ENABLE_FEATURE_TELNETD_STANDALONE |
230 | enum { sock = 0 }; | ||
231 | #endif | ||
232 | niro | 816 | const char *login_argv[2]; |
233 | niro | 532 | struct termios termbuf; |
234 | int fd, pid; | ||
235 | niro | 816 | char tty_name[GETPTY_BUFSIZE]; |
236 | niro | 532 | struct tsession *ts = xzalloc(sizeof(struct tsession) + BUFSIZE * 2); |
237 | |||
238 | niro | 816 | /*ts->buf1 = (char *)(ts + 1);*/ |
239 | /*ts->buf2 = ts->buf1 + BUFSIZE;*/ | ||
240 | niro | 532 | |
241 | niro | 984 | /* Got a new connection, set up a tty */ |
242 | niro | 816 | fd = xgetpty(tty_name); |
243 | niro | 984 | if (fd > G.maxfd) |
244 | G.maxfd = fd; | ||
245 | niro | 816 | ts->ptyfd = fd; |
246 | ndelay_on(fd); | ||
247 | niro | 984 | close_on_exec_on(fd); |
248 | |||
249 | niro | 816 | /* SO_KEEPALIVE by popular demand */ |
250 | setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, &const_int_1, sizeof(const_int_1)); | ||
251 | niro | 1123 | #if ENABLE_FEATURE_TELNETD_STANDALONE |
252 | niro | 984 | ts->sockfd_read = sock; |
253 | niro | 816 | ndelay_on(sock); |
254 | niro | 984 | if (sock == 0) { /* We are called with fd 0 - we are in inetd mode */ |
255 | niro | 816 | sock++; /* so use fd 1 for output */ |
256 | ndelay_on(sock); | ||
257 | niro | 532 | } |
258 | niro | 816 | ts->sockfd_write = sock; |
259 | niro | 984 | if (sock > G.maxfd) |
260 | G.maxfd = sock; | ||
261 | niro | 532 | #else |
262 | niro | 816 | /* ts->sockfd_read = 0; - done by xzalloc */ |
263 | niro | 532 | ts->sockfd_write = 1; |
264 | ndelay_on(0); | ||
265 | ndelay_on(1); | ||
266 | #endif | ||
267 | niro | 984 | |
268 | niro | 532 | /* Make the telnet client understand we will echo characters so it |
269 | * should not do it locally. We don't tell the client to run linemode, | ||
270 | * because we want to handle line editing and tab completion and other | ||
271 | * stuff that requires char-by-char support. */ | ||
272 | niro | 816 | { |
273 | static const char iacs_to_send[] ALIGN1 = { | ||
274 | IAC, DO, TELOPT_ECHO, | ||
275 | IAC, DO, TELOPT_NAWS, | ||
276 | niro | 984 | /* This requires telnetd.ctrlSQ.patch (incomplete) */ |
277 | /* IAC, DO, TELOPT_LFLOW, */ | ||
278 | niro | 816 | IAC, WILL, TELOPT_ECHO, |
279 | IAC, WILL, TELOPT_SGA | ||
280 | }; | ||
281 | niro | 984 | /* This confuses iac_safe_write(), it will try to duplicate |
282 | * each IAC... */ | ||
283 | //memcpy(TS_BUF2(ts), iacs_to_send, sizeof(iacs_to_send)); | ||
284 | //ts->rdidx2 = sizeof(iacs_to_send); | ||
285 | //ts->size2 = sizeof(iacs_to_send); | ||
286 | /* So just stuff it into TCP stream! (no error check...) */ | ||
287 | #if ENABLE_FEATURE_TELNETD_STANDALONE | ||
288 | safe_write(sock, iacs_to_send, sizeof(iacs_to_send)); | ||
289 | #else | ||
290 | safe_write(1, iacs_to_send, sizeof(iacs_to_send)); | ||
291 | #endif | ||
292 | /*ts->rdidx2 = 0; - xzalloc did it */ | ||
293 | /*ts->size2 = 0;*/ | ||
294 | niro | 816 | } |
295 | niro | 532 | |
296 | niro | 984 | fflush_all(); |
297 | niro | 816 | pid = vfork(); /* NOMMU-friendly */ |
298 | niro | 532 | if (pid < 0) { |
299 | free(ts); | ||
300 | close(fd); | ||
301 | niro | 816 | /* sock will be closed by caller */ |
302 | bb_perror_msg("vfork"); | ||
303 | niro | 532 | return NULL; |
304 | } | ||
305 | if (pid > 0) { | ||
306 | niro | 816 | /* Parent */ |
307 | niro | 532 | ts->shell_pid = pid; |
308 | return ts; | ||
309 | } | ||
310 | |||
311 | niro | 816 | /* Child */ |
312 | /* Careful - we are after vfork! */ | ||
313 | niro | 532 | |
314 | niro | 984 | /* Restore default signal handling ASAP */ |
315 | bb_signals((1 << SIGCHLD) + (1 << SIGPIPE), SIG_DFL); | ||
316 | |||
317 | niro | 1123 | if (ENABLE_FEATURE_UTMP) { |
318 | len_and_sockaddr *lsa = get_peer_lsa(sock); | ||
319 | char *hostname = NULL; | ||
320 | if (lsa) { | ||
321 | hostname = xmalloc_sockaddr2dotted(&lsa->u.sa); | ||
322 | free(lsa); | ||
323 | } | ||
324 | write_new_utmp(pid, LOGIN_PROCESS, tty_name, /*username:*/ "LOGIN", hostname); | ||
325 | free(hostname); | ||
326 | } | ||
327 | |||
328 | niro | 984 | /* Make new session and process group */ |
329 | niro | 532 | setsid(); |
330 | |||
331 | niro | 984 | /* Open the child's side of the tty */ |
332 | niro | 532 | /* NB: setsid() disconnects from any previous ctty's. Therefore |
333 | * we must open child's side of the tty AFTER setsid! */ | ||
334 | niro | 816 | close(0); |
335 | xopen(tty_name, O_RDWR); /* becomes our ctty */ | ||
336 | xdup2(0, 1); | ||
337 | xdup2(0, 2); | ||
338 | niro | 1123 | pid = getpid(); |
339 | tcsetpgrp(0, pid); /* switch this tty's process group to us */ | ||
340 | niro | 532 | |
341 | niro | 984 | /* The pseudo-terminal allocated to the client is configured to operate |
342 | * in cooked mode, and with XTABS CRMOD enabled (see tty(4)) */ | ||
343 | niro | 532 | tcgetattr(0, &termbuf); |
344 | termbuf.c_lflag |= ECHO; /* if we use readline we dont want this */ | ||
345 | niro | 816 | termbuf.c_oflag |= ONLCR | XTABS; |
346 | niro | 532 | termbuf.c_iflag |= ICRNL; |
347 | termbuf.c_iflag &= ~IXOFF; | ||
348 | /*termbuf.c_lflag &= ~ICANON;*/ | ||
349 | niro | 816 | tcsetattr_stdin_TCSANOW(&termbuf); |
350 | niro | 532 | |
351 | niro | 984 | /* Uses FILE-based I/O to stdout, but does fflush_all(), |
352 | niro | 816 | * so should be safe with vfork. |
353 | * I fear, though, that some users will have ridiculously big | ||
354 | * issue files, and they may block writing to fd 1, | ||
355 | * (parent is supposed to read it, but parent waits | ||
356 | * for vforked child to exec!) */ | ||
357 | niro | 984 | print_login_issue(G.issuefile, tty_name); |
358 | niro | 532 | |
359 | niro | 816 | /* Exec shell / login / whatever */ |
360 | niro | 984 | login_argv[0] = G.loginpath; |
361 | niro | 816 | login_argv[1] = NULL; |
362 | /* exec busybox applet (if PREFER_APPLETS=y), if that fails, | ||
363 | niro | 984 | * exec external program. |
364 | * NB: sock is either 0 or has CLOEXEC set on it. | ||
365 | * fd has CLOEXEC set on it too. These two fds will be closed here. | ||
366 | */ | ||
367 | BB_EXECVP(G.loginpath, (char **)login_argv); | ||
368 | niro | 816 | /* _exit is safer with vfork, and we shouldn't send message |
369 | * to remote clients anyway */ | ||
370 | niro | 984 | _exit(EXIT_FAILURE); /*bb_perror_msg_and_die("execv %s", G.loginpath);*/ |
371 | niro | 532 | } |
372 | |||
373 | #if ENABLE_FEATURE_TELNETD_STANDALONE | ||
374 | |||
375 | static void | ||
376 | free_session(struct tsession *ts) | ||
377 | { | ||
378 | niro | 1123 | struct tsession *t; |
379 | niro | 532 | |
380 | niro | 816 | if (option_mask32 & OPT_INETD) |
381 | exit(EXIT_SUCCESS); | ||
382 | |||
383 | /* Unlink this telnet session from the session list */ | ||
384 | niro | 1123 | t = G.sessions; |
385 | niro | 532 | if (t == ts) |
386 | niro | 984 | G.sessions = ts->next; |
387 | niro | 532 | else { |
388 | while (t->next != ts) | ||
389 | t = t->next; | ||
390 | t->next = ts->next; | ||
391 | } | ||
392 | |||
393 | niro | 816 | #if 0 |
394 | /* It was said that "normal" telnetd just closes ptyfd, | ||
395 | * doesn't send SIGKILL. When we close ptyfd, | ||
396 | * kernel sends SIGHUP to processes having slave side opened. */ | ||
397 | niro | 532 | kill(ts->shell_pid, SIGKILL); |
398 | niro | 984 | waitpid(ts->shell_pid, NULL, 0); |
399 | niro | 816 | #endif |
400 | niro | 532 | close(ts->ptyfd); |
401 | close(ts->sockfd_read); | ||
402 | niro | 816 | /* We do not need to close(ts->sockfd_write), it's the same |
403 | * as sockfd_read unless we are in inetd mode. But in inetd mode | ||
404 | * we do not reach this */ | ||
405 | niro | 532 | free(ts); |
406 | |||
407 | niro | 816 | /* Scan all sessions and find new maxfd */ |
408 | niro | 984 | G.maxfd = 0; |
409 | ts = G.sessions; | ||
410 | niro | 532 | while (ts) { |
411 | niro | 984 | if (G.maxfd < ts->ptyfd) |
412 | G.maxfd = ts->ptyfd; | ||
413 | if (G.maxfd < ts->sockfd_read) | ||
414 | G.maxfd = ts->sockfd_read; | ||
415 | niro | 816 | #if 0 |
416 | /* Again, sockfd_write == sockfd_read here */ | ||
417 | niro | 984 | if (G.maxfd < ts->sockfd_write) |
418 | G.maxfd = ts->sockfd_write; | ||
419 | niro | 816 | #endif |
420 | niro | 532 | ts = ts->next; |
421 | } | ||
422 | } | ||
423 | |||
424 | #else /* !FEATURE_TELNETD_STANDALONE */ | ||
425 | |||
426 | niro | 816 | /* Used in main() only, thus "return 0" actually is exit(EXIT_SUCCESS). */ |
427 | #define free_session(ts) return 0 | ||
428 | niro | 532 | |
429 | #endif | ||
430 | |||
431 | niro | 816 | static void handle_sigchld(int sig UNUSED_PARAM) |
432 | { | ||
433 | pid_t pid; | ||
434 | struct tsession *ts; | ||
435 | niro | 1123 | int save_errno = errno; |
436 | niro | 532 | |
437 | niro | 816 | /* Looping: more than one child may have exited */ |
438 | while (1) { | ||
439 | pid = wait_any_nohang(NULL); | ||
440 | if (pid <= 0) | ||
441 | break; | ||
442 | niro | 984 | ts = G.sessions; |
443 | niro | 816 | while (ts) { |
444 | if (ts->shell_pid == pid) { | ||
445 | ts->shell_pid = -1; | ||
446 | niro | 1123 | // man utmp: |
447 | // When init(8) finds that a process has exited, it locates its utmp entry | ||
448 | // by ut_pid, sets ut_type to DEAD_PROCESS, and clears ut_user, ut_host | ||
449 | // and ut_time with null bytes. | ||
450 | // [same applies to other processes which maintain utmp entries, like telnetd] | ||
451 | // | ||
452 | // We do not bother actually clearing fields: | ||
453 | // it might be interesting to know who was logged in and from where | ||
454 | update_utmp(pid, DEAD_PROCESS, /*tty_name:*/ NULL, /*username:*/ NULL, /*hostname:*/ NULL); | ||
455 | niro | 816 | break; |
456 | } | ||
457 | ts = ts->next; | ||
458 | } | ||
459 | } | ||
460 | niro | 1123 | |
461 | errno = save_errno; | ||
462 | niro | 816 | } |
463 | |||
464 | int telnetd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; | ||
465 | int telnetd_main(int argc UNUSED_PARAM, char **argv) | ||
466 | niro | 532 | { |
467 | fd_set rdfdset, wrfdset; | ||
468 | unsigned opt; | ||
469 | niro | 816 | int count; |
470 | niro | 532 | struct tsession *ts; |
471 | #if ENABLE_FEATURE_TELNETD_STANDALONE | ||
472 | #define IS_INETD (opt & OPT_INETD) | ||
473 | niro | 984 | int master_fd = master_fd; /* for compiler */ |
474 | int sec_linger = sec_linger; | ||
475 | niro | 532 | char *opt_bindaddr = NULL; |
476 | char *opt_portnbr; | ||
477 | #else | ||
478 | enum { | ||
479 | IS_INETD = 1, | ||
480 | master_fd = -1, | ||
481 | }; | ||
482 | #endif | ||
483 | niro | 984 | INIT_G(); |
484 | |||
485 | /* -w NUM, and implies -F. -w and -i don't mix */ | ||
486 | IF_FEATURE_TELNETD_INETD_WAIT(opt_complementary = "wF:w+:i--w:w--i";) | ||
487 | niro | 816 | /* Even if !STANDALONE, we accept (and ignore) -i, thus people |
488 | * don't need to guess whether it's ok to pass -i to us */ | ||
489 | niro | 984 | opt = getopt32(argv, "f:l:Ki" |
490 | IF_FEATURE_TELNETD_STANDALONE("p:b:F") | ||
491 | IF_FEATURE_TELNETD_INETD_WAIT("Sw:"), | ||
492 | &G.issuefile, &G.loginpath | ||
493 | IF_FEATURE_TELNETD_STANDALONE(, &opt_portnbr, &opt_bindaddr) | ||
494 | IF_FEATURE_TELNETD_INETD_WAIT(, &sec_linger) | ||
495 | ); | ||
496 | niro | 816 | if (!IS_INETD /*&& !re_execed*/) { |
497 | /* inform that we start in standalone mode? | ||
498 | * May be useful when people forget to give -i */ | ||
499 | /*bb_error_msg("listening for connections");*/ | ||
500 | if (!(opt & OPT_FOREGROUND)) { | ||
501 | /* DAEMON_CHDIR_ROOT was giving inconsistent | ||
502 | * behavior with/without -F, -i */ | ||
503 | bb_daemonize_or_rexec(0 /*was DAEMON_CHDIR_ROOT*/, argv); | ||
504 | } | ||
505 | } | ||
506 | niro | 532 | /* Redirect log to syslog early, if needed */ |
507 | niro | 984 | if (IS_INETD || (opt & OPT_SYSLOG) || !(opt & OPT_FOREGROUND)) { |
508 | openlog(applet_name, LOG_PID, LOG_DAEMON); | ||
509 | niro | 532 | logmode = LOGMODE_SYSLOG; |
510 | } | ||
511 | #if ENABLE_FEATURE_TELNETD_STANDALONE | ||
512 | if (IS_INETD) { | ||
513 | niro | 984 | G.sessions = make_new_session(0); |
514 | if (!G.sessions) /* pty opening or vfork problem, exit */ | ||
515 | return 1; /* make_new_session printed error message */ | ||
516 | niro | 532 | } else { |
517 | niro | 984 | master_fd = 0; |
518 | if (!(opt & OPT_WAIT)) { | ||
519 | unsigned portnbr = 23; | ||
520 | if (opt & OPT_PORT) | ||
521 | portnbr = xatou16(opt_portnbr); | ||
522 | master_fd = create_and_bind_stream_or_die(opt_bindaddr, portnbr); | ||
523 | xlisten(master_fd, 1); | ||
524 | } | ||
525 | close_on_exec_on(master_fd); | ||
526 | niro | 532 | } |
527 | #else | ||
528 | niro | 984 | G.sessions = make_new_session(); |
529 | if (!G.sessions) /* pty opening or vfork problem, exit */ | ||
530 | return 1; /* make_new_session printed error message */ | ||
531 | niro | 532 | #endif |
532 | |||
533 | /* We don't want to die if just one session is broken */ | ||
534 | signal(SIGPIPE, SIG_IGN); | ||
535 | |||
536 | niro | 816 | if (opt & OPT_WATCHCHILD) |
537 | signal(SIGCHLD, handle_sigchld); | ||
538 | else /* prevent dead children from becoming zombies */ | ||
539 | signal(SIGCHLD, SIG_IGN); | ||
540 | |||
541 | /* | ||
542 | niro | 984 | This is how the buffers are used. The arrows indicate data flow. |
543 | |||
544 | niro | 816 | +-------+ wridx1++ +------+ rdidx1++ +----------+ |
545 | | | <-------------- | buf1 | <-------------- | | | ||
546 | | | size1-- +------+ size1++ | | | ||
547 | | pty | | socket | | ||
548 | | | rdidx2++ +------+ wridx2++ | | | ||
549 | | | --------------> | buf2 | --------------> | | | ||
550 | +-------+ size2++ +------+ size2-- +----------+ | ||
551 | |||
552 | size1: "how many bytes are buffered for pty between rdidx1 and wridx1?" | ||
553 | size2: "how many bytes are buffered for socket between rdidx2 and wridx2?" | ||
554 | |||
555 | Each session has got two buffers. Buffers are circular. If sizeN == 0, | ||
556 | buffer is empty. If sizeN == BUFSIZE, buffer is full. In both these cases | ||
557 | rdidxN == wridxN. | ||
558 | */ | ||
559 | niro | 532 | again: |
560 | FD_ZERO(&rdfdset); | ||
561 | FD_ZERO(&wrfdset); | ||
562 | niro | 816 | |
563 | /* Select on the master socket, all telnet sockets and their | ||
564 | * ptys if there is room in their session buffers. | ||
565 | * NB: scalability problem: we recalculate entire bitmap | ||
566 | * before each select. Can be a problem with 500+ connections. */ | ||
567 | niro | 984 | ts = G.sessions; |
568 | niro | 816 | while (ts) { |
569 | niro | 984 | struct tsession *next = ts->next; /* in case we free ts */ |
570 | niro | 816 | if (ts->shell_pid == -1) { |
571 | /* Child died and we detected that */ | ||
572 | free_session(ts); | ||
573 | } else { | ||
574 | if (ts->size1 > 0) /* can write to pty */ | ||
575 | FD_SET(ts->ptyfd, &wrfdset); | ||
576 | if (ts->size1 < BUFSIZE) /* can read from socket */ | ||
577 | FD_SET(ts->sockfd_read, &rdfdset); | ||
578 | if (ts->size2 > 0) /* can write to socket */ | ||
579 | FD_SET(ts->sockfd_write, &wrfdset); | ||
580 | if (ts->size2 < BUFSIZE) /* can read from pty */ | ||
581 | FD_SET(ts->ptyfd, &rdfdset); | ||
582 | } | ||
583 | ts = next; | ||
584 | } | ||
585 | niro | 532 | if (!IS_INETD) { |
586 | FD_SET(master_fd, &rdfdset); | ||
587 | /* This is needed because free_session() does not | ||
588 | niro | 816 | * take master_fd into account when it finds new |
589 | * maxfd among remaining fd's */ | ||
590 | niro | 984 | if (master_fd > G.maxfd) |
591 | G.maxfd = master_fd; | ||
592 | niro | 532 | } |
593 | |||
594 | niro | 984 | { |
595 | struct timeval *tv_ptr = NULL; | ||
596 | #if ENABLE_FEATURE_TELNETD_INETD_WAIT | ||
597 | struct timeval tv; | ||
598 | if ((opt & OPT_WAIT) && !G.sessions) { | ||
599 | tv.tv_sec = sec_linger; | ||
600 | tv.tv_usec = 0; | ||
601 | tv_ptr = &tv; | ||
602 | } | ||
603 | #endif | ||
604 | count = select(G.maxfd + 1, &rdfdset, &wrfdset, NULL, tv_ptr); | ||
605 | } | ||
606 | if (count == 0) /* "telnetd -w SEC" timed out */ | ||
607 | return 0; | ||
608 | niro | 816 | if (count < 0) |
609 | goto again; /* EINTR or ENOMEM */ | ||
610 | niro | 532 | |
611 | #if ENABLE_FEATURE_TELNETD_STANDALONE | ||
612 | niro | 984 | /* Check for and accept new sessions */ |
613 | niro | 532 | if (!IS_INETD && FD_ISSET(master_fd, &rdfdset)) { |
614 | int fd; | ||
615 | struct tsession *new_ts; | ||
616 | |||
617 | niro | 816 | fd = accept(master_fd, NULL, NULL); |
618 | niro | 532 | if (fd < 0) |
619 | goto again; | ||
620 | niro | 984 | close_on_exec_on(fd); |
621 | |||
622 | /* Create a new session and link it into active list */ | ||
623 | niro | 816 | new_ts = make_new_session(fd); |
624 | niro | 532 | if (new_ts) { |
625 | niro | 984 | new_ts->next = G.sessions; |
626 | G.sessions = new_ts; | ||
627 | niro | 532 | } else { |
628 | close(fd); | ||
629 | } | ||
630 | } | ||
631 | #endif | ||
632 | |||
633 | niro | 984 | /* Then check for data tunneling */ |
634 | ts = G.sessions; | ||
635 | niro | 532 | while (ts) { /* For all sessions... */ |
636 | niro | 984 | struct tsession *next = ts->next; /* in case we free ts */ |
637 | niro | 532 | |
638 | niro | 816 | if (/*ts->size1 &&*/ FD_ISSET(ts->ptyfd, &wrfdset)) { |
639 | niro | 532 | int num_totty; |
640 | niro | 816 | unsigned char *ptr; |
641 | niro | 984 | /* Write to pty from buffer 1 */ |
642 | niro | 532 | ptr = remove_iacs(ts, &num_totty); |
643 | niro | 816 | count = safe_write(ts->ptyfd, ptr, num_totty); |
644 | if (count < 0) { | ||
645 | if (errno == EAGAIN) | ||
646 | goto skip1; | ||
647 | goto kill_session; | ||
648 | niro | 532 | } |
649 | niro | 816 | ts->size1 -= count; |
650 | ts->wridx1 += count; | ||
651 | if (ts->wridx1 >= BUFSIZE) /* actually == BUFSIZE */ | ||
652 | niro | 532 | ts->wridx1 = 0; |
653 | } | ||
654 | niro | 816 | skip1: |
655 | if (/*ts->size2 &&*/ FD_ISSET(ts->sockfd_write, &wrfdset)) { | ||
656 | niro | 984 | /* Write to socket from buffer 2 */ |
657 | niro | 816 | count = MIN(BUFSIZE - ts->wridx2, ts->size2); |
658 | niro | 984 | count = iac_safe_write(ts->sockfd_write, (void*)(TS_BUF2(ts) + ts->wridx2), count); |
659 | niro | 816 | if (count < 0) { |
660 | if (errno == EAGAIN) | ||
661 | goto skip2; | ||
662 | goto kill_session; | ||
663 | niro | 532 | } |
664 | niro | 816 | ts->size2 -= count; |
665 | ts->wridx2 += count; | ||
666 | if (ts->wridx2 >= BUFSIZE) /* actually == BUFSIZE */ | ||
667 | niro | 532 | ts->wridx2 = 0; |
668 | } | ||
669 | niro | 816 | skip2: |
670 | /* Should not be needed, but... remove_iacs is actually buggy | ||
671 | * (it cannot process iacs which wrap around buffer's end)! | ||
672 | * Since properly fixing it requires writing bigger code, | ||
673 | * we rely instead on this code making it virtually impossible | ||
674 | * to have wrapped iac (people don't type at 2k/second). | ||
675 | * It also allows for bigger reads in common case. */ | ||
676 | if (ts->size1 == 0) { | ||
677 | ts->rdidx1 = 0; | ||
678 | ts->wridx1 = 0; | ||
679 | } | ||
680 | if (ts->size2 == 0) { | ||
681 | ts->rdidx2 = 0; | ||
682 | ts->wridx2 = 0; | ||
683 | } | ||
684 | niro | 532 | |
685 | niro | 816 | if (/*ts->size1 < BUFSIZE &&*/ FD_ISSET(ts->sockfd_read, &rdfdset)) { |
686 | niro | 984 | /* Read from socket to buffer 1 */ |
687 | niro | 816 | count = MIN(BUFSIZE - ts->rdidx1, BUFSIZE - ts->size1); |
688 | niro | 984 | count = safe_read(ts->sockfd_read, TS_BUF1(ts) + ts->rdidx1, count); |
689 | niro | 816 | if (count <= 0) { |
690 | if (count < 0 && errno == EAGAIN) | ||
691 | goto skip3; | ||
692 | goto kill_session; | ||
693 | niro | 532 | } |
694 | niro | 816 | /* Ignore trailing NUL if it is there */ |
695 | niro | 984 | if (!TS_BUF1(ts)[ts->rdidx1 + count - 1]) { |
696 | niro | 816 | --count; |
697 | } | ||
698 | ts->size1 += count; | ||
699 | ts->rdidx1 += count; | ||
700 | if (ts->rdidx1 >= BUFSIZE) /* actually == BUFSIZE */ | ||
701 | niro | 532 | ts->rdidx1 = 0; |
702 | } | ||
703 | niro | 816 | skip3: |
704 | if (/*ts->size2 < BUFSIZE &&*/ FD_ISSET(ts->ptyfd, &rdfdset)) { | ||
705 | niro | 984 | /* Read from pty to buffer 2 */ |
706 | niro | 816 | count = MIN(BUFSIZE - ts->rdidx2, BUFSIZE - ts->size2); |
707 | niro | 984 | count = safe_read(ts->ptyfd, TS_BUF2(ts) + ts->rdidx2, count); |
708 | niro | 816 | if (count <= 0) { |
709 | if (count < 0 && errno == EAGAIN) | ||
710 | goto skip4; | ||
711 | goto kill_session; | ||
712 | niro | 532 | } |
713 | niro | 816 | ts->size2 += count; |
714 | ts->rdidx2 += count; | ||
715 | if (ts->rdidx2 >= BUFSIZE) /* actually == BUFSIZE */ | ||
716 | niro | 532 | ts->rdidx2 = 0; |
717 | } | ||
718 | niro | 816 | skip4: |
719 | niro | 532 | ts = next; |
720 | niro | 816 | continue; |
721 | kill_session: | ||
722 | niro | 1123 | if (ts->shell_pid > 0) |
723 | update_utmp(ts->shell_pid, DEAD_PROCESS, /*tty_name:*/ NULL, /*username:*/ NULL, /*hostname:*/ NULL); | ||
724 | niro | 816 | free_session(ts); |
725 | ts = next; | ||
726 | niro | 532 | } |
727 | niro | 816 | |
728 | niro | 532 | goto again; |
729 | } |