*
* The telnetd manpage says it all:
*
- * Telnetd operates by allocating a pseudo-terminal device (see pty(4)) for
- * a client, then creating a login process which has the slave side of the
- * pseudo-terminal as stdin, stdout, and stderr. Telnetd manipulates the
- * master side of the pseudo-terminal, implementing the telnet protocol and
- * passing characters between the remote client and the login process.
+ * Telnetd operates by allocating a pseudo-terminal device (see pty(4)) for
+ * a client, then creating a login process which has the slave side of the
+ * pseudo-terminal as stdin, stdout, and stderr. Telnetd manipulates the
+ * master side of the pseudo-terminal, implementing the telnet protocol and
+ * passing characters between the remote client and the login process.
*
* Vladimir Oleynik <dzo@simtreas.ru> 2001
- * Set process group corrections, initial busybox port
+ * Set process group corrections, initial busybox port
*/
#define DEBUG 0
#include "libbb.h"
+#include <syslog.h>
#if DEBUG
#define TELCMDS
#define TELOPTS
#endif
#include <arpa/telnet.h>
-#include <sys/syslog.h>
-
-/* Structure that describes a session */
struct tsession {
struct tsession *next;
- int sockfd_read, sockfd_write, ptyfd;
- /*int shell_pid;*/
+ pid_t shell_pid;
+ int sockfd_read;
+ int sockfd_write;
+ int ptyfd;
/* two circular buffers */
/*char *buf1, *buf2;*/
-/*#define TS_BUF1 ts->buf1*/
-/*#define TS_BUF2 TS_BUF2*/
-#define TS_BUF1 ((unsigned char*)(ts + 1))
-#define TS_BUF2 (((unsigned char*)(ts + 1)) + BUFSIZE)
+/*#define TS_BUF1(ts) ts->buf1*/
+/*#define TS_BUF2(ts) TS_BUF2(ts)*/
+#define TS_BUF1(ts) ((unsigned char*)(ts + 1))
+#define TS_BUF2(ts) (((unsigned char*)(ts + 1)) + BUFSIZE)
int rdidx1, wridx1, size1;
int rdidx2, wridx2, size2;
};
/* Globals */
-static int maxfd;
-static struct tsession *sessions;
-#if ENABLE_LOGIN
-static const char *loginpath = "/bin/login";
-#else
-static const char *loginpath = DEFAULT_SHELL;
-#endif
-static const char *issuefile = "/etc/issue.net";
+struct globals {
+ struct tsession *sessions;
+ const char *loginpath;
+ const char *issuefile;
+ int maxfd;
+};
+#define G (*(struct globals*)&bb_common_bufsiz1)
+#define INIT_G() do { \
+ G.loginpath = "/bin/login"; \
+ G.issuefile = "/etc/issue.net"; \
+} while (0)
/*
past (bf + len) then that IAC will be left unprocessed and *processed
will be less than len.
- FIXME - if we mean to send 0xFF to the terminal then it will be escaped,
- what is the escape character? We aren't handling that situation here.
-
CR-LF ->'s CR mapping is also done here, for convenience.
NB: may fail to remove iacs which wrap around buffer!
static unsigned char *
remove_iacs(struct tsession *ts, int *pnum_totty)
{
- unsigned char *ptr0 = TS_BUF1 + ts->wridx1;
+ unsigned char *ptr0 = TS_BUF1(ts) + ts->wridx1;
unsigned char *ptr = ptr0;
unsigned char *totty = ptr;
unsigned char *end = ptr + MIN(BUFSIZE - ts->wridx1, ts->size1);
*totty++ = c;
ptr++;
- /* We now map \r\n ==> \r for pragmatic reasons.
+ /* We map \r\n ==> \r for pragmatic reasons.
* Many client implementations send \r\n when
* the user hits the CarriageReturn key.
*/
if (c == '\r' && ptr < end && (*ptr == '\n' || *ptr == '\0'))
ptr++;
- } else {
- /*
- * TELOPT_NAWS support!
- */
- if ((ptr+2) >= end) {
- /* only the beginning of the IAC is in the
- buffer we were asked to process, we can't
- process this char. */
- break;
- }
+ continue;
+ }
- /*
- * IAC -> SB -> TELOPT_NAWS -> 4-byte -> IAC -> SE
- */
- else if (ptr[1] == SB && ptr[2] == TELOPT_NAWS) {
- struct winsize ws;
-
- if ((ptr+8) >= end)
- break; /* incomplete, can't process */
- ws.ws_col = (ptr[3] << 8) | ptr[4];
- ws.ws_row = (ptr[5] << 8) | ptr[6];
- ioctl(ts->ptyfd, TIOCSWINSZ, (char *)&ws);
- ptr += 9;
- } else {
- /* skip 3-byte IAC non-SB cmd */
+ if ((ptr+1) >= end)
+ break;
+ if (ptr[1] == NOP) { /* Ignore? (putty keepalive, etc.) */
+ ptr += 2;
+ continue;
+ }
+ if (ptr[1] == IAC) { /* Literal IAC? (emacs M-DEL) */
+ *totty++ = ptr[1];
+ ptr += 2;
+ continue;
+ }
+
+ /*
+ * TELOPT_NAWS support!
+ */
+ if ((ptr+2) >= end) {
+ /* Only the beginning of the IAC is in the
+ buffer we were asked to process, we can't
+ process this char */
+ break;
+ }
+ /*
+ * IAC -> SB -> TELOPT_NAWS -> 4-byte -> IAC -> SE
+ */
+ if (ptr[1] == SB && ptr[2] == TELOPT_NAWS) {
+ struct winsize ws;
+ if ((ptr+8) >= end)
+ break; /* incomplete, can't process */
+ ws.ws_col = (ptr[3] << 8) | ptr[4];
+ ws.ws_row = (ptr[5] << 8) | ptr[6];
+ ioctl(ts->ptyfd, TIOCSWINSZ, (char *)&ws);
+ ptr += 9;
+ continue;
+ }
+ /* skip 3-byte IAC non-SB cmd */
#if DEBUG
- fprintf(stderr, "Ignoring IAC %s,%s\n",
- TELCMD(ptr[1]), TELOPT(ptr[2]));
+ fprintf(stderr, "Ignoring IAC %s,%s\n",
+ TELCMD(ptr[1]), TELOPT(ptr[2]));
#endif
- ptr += 3;
- }
- }
+ ptr += 3;
}
- num_totty = totty - ptr0;
+ num_totty = totty - ptr0;
*pnum_totty = num_totty;
- /* the difference between ptr and totty is number of iacs
- we removed from the stream. Adjust buf1 accordingly. */
+ /* The difference between ptr and totty is number of iacs
+ we removed from the stream. Adjust buf1 accordingly */
if ((ptr - totty) == 0) /* 99.999% of cases */
return ptr0;
ts->wridx1 += ptr - totty;
ts->size1 -= ptr - totty;
- /* move chars meant for the terminal towards the end of the buffer */
+ /* Move chars meant for the terminal towards the end of the buffer */
return memmove(ptr - num_totty, ptr0, num_totty);
}
-
-static int
-getpty(char *line, int size)
+/*
+ * Converting single IAC into double on output
+ */
+static size_t iac_safe_write(int fd, const char *buf, size_t count)
{
- int p;
-#if ENABLE_FEATURE_DEVPTS
- p = open("/dev/ptmx", O_RDWR);
- if (p > 0) {
- const char *name;
- grantpt(p);
- unlockpt(p);
- name = ptsname(p);
- if (!name) {
- bb_perror_msg("ptsname error (is /dev/pts mounted?)");
- return -1;
- }
- safe_strncpy(line, name, size);
- return p;
- }
-#else
- struct stat stb;
- int i;
- int j;
-
- strcpy(line, "/dev/ptyXX");
-
- for (i = 0; i < 16; i++) {
- line[8] = "pqrstuvwxyzabcde"[i];
- line[9] = '0';
- if (stat(line, &stb) < 0) {
+ const char *IACptr;
+ size_t wr, rc, total;
+
+ total = 0;
+ while (1) {
+ if (count == 0)
+ return total;
+ if (*buf == (char)IAC) {
+ static const char IACIAC[] ALIGN1 = { IAC, IAC };
+ rc = safe_write(fd, IACIAC, 2);
+ if (rc != 2)
+ break;
+ buf++;
+ total++;
+ count--;
continue;
}
- for (j = 0; j < 16; j++) {
- line[9] = j < 10 ? j + '0' : j - 10 + 'a';
- if (DEBUG)
- fprintf(stderr, "Trying to open device: %s\n", line);
- p = open(line, O_RDWR | O_NOCTTY);
- if (p >= 0) {
- line[5] = 't';
- return p;
- }
- }
+ /* count != 0, *buf != IAC */
+ IACptr = memchr(buf, IAC, count);
+ wr = count;
+ if (IACptr)
+ wr = IACptr - buf;
+ rc = safe_write(fd, buf, wr);
+ if (rc != wr)
+ break;
+ buf += rc;
+ total += rc;
+ count -= rc;
}
-#endif /* FEATURE_DEVPTS */
- return -1;
+ /* here: rc - result of last short write */
+ if ((ssize_t)rc < 0) { /* error? */
+ if (total == 0)
+ return rc;
+ rc = 0;
+ }
+ return total + rc;
}
+/* Must match getopt32 string */
+enum {
+ OPT_WATCHCHILD = (1 << 2), /* -K */
+ OPT_INETD = (1 << 3) * ENABLE_FEATURE_TELNETD_STANDALONE, /* -i */
+ OPT_PORT = (1 << 4) * ENABLE_FEATURE_TELNETD_STANDALONE, /* -p PORT */
+ OPT_FOREGROUND = (1 << 6) * ENABLE_FEATURE_TELNETD_STANDALONE, /* -F */
+ OPT_SYSLOG = (1 << 7) * ENABLE_FEATURE_TELNETD_INETD_WAIT, /* -S */
+ OPT_WAIT = (1 << 8) * ENABLE_FEATURE_TELNETD_INETD_WAIT, /* -w SEC */
+};
static struct tsession *
make_new_session(
- USE_FEATURE_TELNETD_STANDALONE(int sock_r, int sock_w)
- SKIP_FEATURE_TELNETD_STANDALONE(void)
+ IF_FEATURE_TELNETD_STANDALONE(int sock)
+ IF_NOT_FEATURE_TELNETD_STANDALONE(void)
) {
const char *login_argv[2];
struct termios termbuf;
int fd, pid;
- char tty_name[32];
+ char tty_name[GETPTY_BUFSIZE];
struct tsession *ts = xzalloc(sizeof(struct tsession) + BUFSIZE * 2);
/*ts->buf1 = (char *)(ts + 1);*/
/*ts->buf2 = ts->buf1 + BUFSIZE;*/
- /* Got a new connection, set up a tty. */
- fd = getpty(tty_name, 32);
- if (fd < 0) {
- bb_error_msg("can't create pty");
- return NULL;
- }
- if (fd > maxfd) maxfd = fd;
+ /* Got a new connection, set up a tty */
+ fd = xgetpty(tty_name);
+ if (fd > G.maxfd)
+ G.maxfd = fd;
ts->ptyfd = fd;
ndelay_on(fd);
+ close_on_exec_on(fd);
+
#if ENABLE_FEATURE_TELNETD_STANDALONE
- if (sock_w > maxfd) maxfd = sock_w;
- ts->sockfd_write = sock_w;
- ndelay_on(sock_w);
- if (sock_r > maxfd) maxfd = sock_r;
- ts->sockfd_read = sock_r;
- ndelay_on(sock_r);
+ /* SO_KEEPALIVE by popular demand */
+ setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, &const_int_1, sizeof(const_int_1));
+ ts->sockfd_read = sock;
+ ndelay_on(sock);
+ if (sock == 0) { /* We are called with fd 0 - we are in inetd mode */
+ sock++; /* so use fd 1 for output */
+ ndelay_on(sock);
+ }
+ ts->sockfd_write = sock;
+ if (sock > G.maxfd)
+ G.maxfd = sock;
#else
- ts->sockfd_write = 1;
+ /* SO_KEEPALIVE by popular demand */
+ setsockopt(0, SOL_SOCKET, SO_KEEPALIVE, &const_int_1, sizeof(const_int_1));
/* ts->sockfd_read = 0; - done by xzalloc */
+ ts->sockfd_write = 1;
ndelay_on(0);
ndelay_on(1);
#endif
+
/* Make the telnet client understand we will echo characters so it
* should not do it locally. We don't tell the client to run linemode,
* because we want to handle line editing and tab completion and other
static const char iacs_to_send[] ALIGN1 = {
IAC, DO, TELOPT_ECHO,
IAC, DO, TELOPT_NAWS,
- IAC, DO, TELOPT_LFLOW,
+ /* This requires telnetd.ctrlSQ.patch (incomplete) */
+ /* IAC, DO, TELOPT_LFLOW, */
IAC, WILL, TELOPT_ECHO,
IAC, WILL, TELOPT_SGA
};
- memcpy(TS_BUF2, iacs_to_send, sizeof(iacs_to_send));
- ts->rdidx2 = sizeof(iacs_to_send);
- ts->size2 = sizeof(iacs_to_send);
+ /* This confuses iac_safe_write(), it will try to duplicate
+ * each IAC... */
+ //memcpy(TS_BUF2(ts), iacs_to_send, sizeof(iacs_to_send));
+ //ts->rdidx2 = sizeof(iacs_to_send);
+ //ts->size2 = sizeof(iacs_to_send);
+ /* So just stuff it into TCP stream! (no error check...) */
+#if ENABLE_FEATURE_TELNETD_STANDALONE
+ safe_write(sock, iacs_to_send, sizeof(iacs_to_send));
+#else
+ safe_write(1, iacs_to_send, sizeof(iacs_to_send));
+#endif
+ /*ts->rdidx2 = 0; - xzalloc did it */
+ /*ts->size2 = 0;*/
}
- fflush(NULL); /* flush all streams */
+ fflush_all();
pid = vfork(); /* NOMMU-friendly */
if (pid < 0) {
free(ts);
close(fd);
- /* sock_r and sock_w will be closed by caller */
+ /* sock will be closed by caller */
bb_perror_msg("vfork");
return NULL;
}
if (pid > 0) {
/* Parent */
- /*ts->shell_pid = pid;*/
+ ts->shell_pid = pid;
return ts;
}
/* Child */
/* Careful - we are after vfork! */
- /* make new session and process group */
+ /* Restore default signal handling ASAP */
+ bb_signals((1 << SIGCHLD) + (1 << SIGPIPE), SIG_DFL);
+
+ /* Make new session and process group */
setsid();
- /* open the child's side of the tty. */
+ /* Open the child's side of the tty */
/* NB: setsid() disconnects from any previous ctty's. Therefore
* we must open child's side of the tty AFTER setsid! */
- fd = xopen(tty_name, O_RDWR); /* becomes our ctty */
- dup2(fd, 0);
- dup2(fd, 1);
- dup2(fd, 2);
- while (fd > 2) close(fd--);
+ close(0);
+ xopen(tty_name, O_RDWR); /* becomes our ctty */
+ xdup2(0, 1);
+ xdup2(0, 2);
tcsetpgrp(0, getpid()); /* switch this tty's process group to us */
- /* The pseudo-terminal allocated to the client is configured to operate in
- * cooked mode, and with XTABS CRMOD enabled (see tty(4)). */
+ /* The pseudo-terminal allocated to the client is configured to operate
+ * in cooked mode, and with XTABS CRMOD enabled (see tty(4)) */
tcgetattr(0, &termbuf);
termbuf.c_lflag |= ECHO; /* if we use readline we dont want this */
termbuf.c_oflag |= ONLCR | XTABS;
termbuf.c_iflag |= ICRNL;
termbuf.c_iflag &= ~IXOFF;
/*termbuf.c_lflag &= ~ICANON;*/
- tcsetattr(0, TCSANOW, &termbuf);
+ tcsetattr_stdin_TCSANOW(&termbuf);
- /* Uses FILE-based I/O to stdout, but does fflush(stdout),
+ /* Uses FILE-based I/O to stdout, but does fflush_all(),
* so should be safe with vfork.
* I fear, though, that some users will have ridiculously big
- * issue files, and they may block writing to fd 1. */
- print_login_issue(issuefile, NULL);
+ * issue files, and they may block writing to fd 1,
+ * (parent is supposed to read it, but parent waits
+ * for vforked child to exec!) */
+ print_login_issue(G.issuefile, tty_name);
/* Exec shell / login / whatever */
- login_argv[0] = loginpath;
+ login_argv[0] = G.loginpath;
login_argv[1] = NULL;
- execvp(loginpath, (char **)login_argv);
- /* Safer with vfork, and we shouldn't send this to the client anyway */
- _exit(1); /*bb_perror_msg_and_die("execv %s", loginpath);*/
+ /* exec busybox applet (if PREFER_APPLETS=y), if that fails,
+ * exec external program.
+ * NB: sock is either 0 or has CLOEXEC set on it.
+ * fd has CLOEXEC set on it too. These two fds will be closed here.
+ */
+ BB_EXECVP(G.loginpath, (char **)login_argv);
+ /* _exit is safer with vfork, and we shouldn't send message
+ * to remote clients anyway */
+ _exit(EXIT_FAILURE); /*bb_perror_msg_and_die("execv %s", G.loginpath);*/
}
#if ENABLE_FEATURE_TELNETD_STANDALONE
static void
free_session(struct tsession *ts)
{
- struct tsession *t = sessions;
+ struct tsession *t = G.sessions;
+
+ if (option_mask32 & OPT_INETD)
+ exit(EXIT_SUCCESS);
/* Unlink this telnet session from the session list */
if (t == ts)
- sessions = ts->next;
+ G.sessions = ts->next;
else {
while (t->next != ts)
t = t->next;
t->next = ts->next;
}
+#if 0
/* It was said that "normal" telnetd just closes ptyfd,
* doesn't send SIGKILL. When we close ptyfd,
* kernel sends SIGHUP to processes having slave side opened. */
- /*kill(ts->shell_pid, SIGKILL);
- wait4(ts->shell_pid, NULL, 0, NULL);*/
+ kill(ts->shell_pid, SIGKILL);
+ waitpid(ts->shell_pid, NULL, 0);
+#endif
close(ts->ptyfd);
close(ts->sockfd_read);
- /* error if ts->sockfd_read == ts->sockfd_write. So what? ;) */
- close(ts->sockfd_write);
+ /* We do not need to close(ts->sockfd_write), it's the same
+ * as sockfd_read unless we are in inetd mode. But in inetd mode
+ * we do not reach this */
free(ts);
/* Scan all sessions and find new maxfd */
- ts = sessions;
- maxfd = 0;
+ G.maxfd = 0;
+ ts = G.sessions;
while (ts) {
- if (maxfd < ts->ptyfd)
- maxfd = ts->ptyfd;
- if (maxfd < ts->sockfd_read)
- maxfd = ts->sockfd_read;
- if (maxfd < ts->sockfd_write)
- maxfd = ts->sockfd_write;
+ if (G.maxfd < ts->ptyfd)
+ G.maxfd = ts->ptyfd;
+ if (G.maxfd < ts->sockfd_read)
+ G.maxfd = ts->sockfd_read;
+#if 0
+ /* Again, sockfd_write == sockfd_read here */
+ if (G.maxfd < ts->sockfd_write)
+ G.maxfd = ts->sockfd_write;
+#endif
ts = ts->next;
}
}
#else /* !FEATURE_TELNETD_STANDALONE */
-/* Never actually called */
-void free_session(struct tsession *ts);
+/* Used in main() only, thus "return 0" actually is exit(EXIT_SUCCESS). */
+#define free_session(ts) return 0
#endif
+static void handle_sigchld(int sig UNUSED_PARAM)
+{
+ pid_t pid;
+ struct tsession *ts;
+
+ /* Looping: more than one child may have exited */
+ while (1) {
+ pid = wait_any_nohang(NULL);
+ if (pid <= 0)
+ break;
+ ts = G.sessions;
+ while (ts) {
+ if (ts->shell_pid == pid) {
+ ts->shell_pid = -1;
+ break;
+ }
+ ts = ts->next;
+ }
+ }
+}
int telnetd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
-int telnetd_main(int argc, char **argv)
+int telnetd_main(int argc UNUSED_PARAM, char **argv)
{
fd_set rdfdset, wrfdset;
unsigned opt;
struct tsession *ts;
#if ENABLE_FEATURE_TELNETD_STANDALONE
#define IS_INETD (opt & OPT_INETD)
- int master_fd = master_fd; /* be happy, gcc */
- unsigned portnbr = 23;
+ int master_fd = master_fd; /* for compiler */
+ int sec_linger = sec_linger;
char *opt_bindaddr = NULL;
char *opt_portnbr;
#else
enum {
IS_INETD = 1,
master_fd = -1,
- portnbr = 23,
};
#endif
- enum {
- OPT_INETD = (1 << 2) * ENABLE_FEATURE_TELNETD_STANDALONE, /* -i */
- OPT_PORT = (1 << 3) * ENABLE_FEATURE_TELNETD_STANDALONE, /* -p */
- OPT_FOREGROUND = (1 << 5) * ENABLE_FEATURE_TELNETD_STANDALONE, /* -F */
- };
+ INIT_G();
- /* If !STANDALONE, we accept (and ignore) -i, thus people
+ /* -w NUM, and implies -F. -w and -i don't mix */
+ IF_FEATURE_TELNETD_INETD_WAIT(opt_complementary = "wF:w+:i--w:w--i";)
+ /* Even if !STANDALONE, we accept (and ignore) -i, thus people
* don't need to guess whether it's ok to pass -i to us */
- opt = getopt32(argv, "f:l:i" USE_FEATURE_TELNETD_STANDALONE("p:b:F"),
- &issuefile, &loginpath
- USE_FEATURE_TELNETD_STANDALONE(, &opt_portnbr, &opt_bindaddr));
+ opt = getopt32(argv, "f:l:Ki"
+ IF_FEATURE_TELNETD_STANDALONE("p:b:F")
+ IF_FEATURE_TELNETD_INETD_WAIT("Sw:"),
+ &G.issuefile, &G.loginpath
+ IF_FEATURE_TELNETD_STANDALONE(, &opt_portnbr, &opt_bindaddr)
+ IF_FEATURE_TELNETD_INETD_WAIT(, &sec_linger)
+ );
+ if (!IS_INETD /*&& !re_execed*/) {
+ /* inform that we start in standalone mode?
+ * May be useful when people forget to give -i */
+ /*bb_error_msg("listening for connections");*/
+ if (!(opt & OPT_FOREGROUND)) {
+ /* DAEMON_CHDIR_ROOT was giving inconsistent
+ * behavior with/without -F, -i */
+ bb_daemonize_or_rexec(0 /*was DAEMON_CHDIR_ROOT*/, argv);
+ }
+ }
/* Redirect log to syslog early, if needed */
- if (IS_INETD || !(opt & OPT_FOREGROUND)) {
- openlog(applet_name, 0, LOG_USER);
+ if (IS_INETD || (opt & OPT_SYSLOG) || !(opt & OPT_FOREGROUND)) {
+ openlog(applet_name, LOG_PID, LOG_DAEMON);
logmode = LOGMODE_SYSLOG;
}
- //if (opt & 1) // -f
- //if (opt & 2) // -l
- USE_FEATURE_TELNETD_STANDALONE(
- if (opt & OPT_PORT) // -p
- portnbr = xatou16(opt_portnbr);
- //if (opt & 8) // -b
- //if (opt & 0x10) // -F
- //if (opt & 0x20) // -i
- );
-
- /* Used to check access(loginpath, X_OK) here. Pointless.
- * exec will do this for us for free later. */
-
#if ENABLE_FEATURE_TELNETD_STANDALONE
if (IS_INETD) {
- sessions = make_new_session(0, 1);
- if (!sessions) /* pty opening or vfork problem, exit */
- return 1; /* make_new_session prints error message */
+ G.sessions = make_new_session(0);
+ if (!G.sessions) /* pty opening or vfork problem, exit */
+ return 1; /* make_new_session printed error message */
} else {
-//vda: inform that we start in standalone mode?
- master_fd = create_and_bind_stream_or_die(opt_bindaddr, portnbr);
- xlisten(master_fd, 1);
- if (!(opt & OPT_FOREGROUND))
-//vda: NOMMU?
- bb_daemonize(DAEMON_CHDIR_ROOT);
+ master_fd = 0;
+ if (!(opt & OPT_WAIT)) {
+ unsigned portnbr = 23;
+ if (opt & OPT_PORT)
+ portnbr = xatou16(opt_portnbr);
+ master_fd = create_and_bind_stream_or_die(opt_bindaddr, portnbr);
+ xlisten(master_fd, 1);
+ }
+ close_on_exec_on(master_fd);
}
#else
- sessions = make_new_session();
- if (!sessions) /* pty opening or vfork problem, exit */
- return 1; /* make_new_session prints error message */
+ G.sessions = make_new_session();
+ if (!G.sessions) /* pty opening or vfork problem, exit */
+ return 1; /* make_new_session printed error message */
#endif
/* We don't want to die if just one session is broken */
signal(SIGPIPE, SIG_IGN);
+ if (opt & OPT_WATCHCHILD)
+ signal(SIGCHLD, handle_sigchld);
+ else /* prevent dead children from becoming zombies */
+ signal(SIGCHLD, SIG_IGN);
+
/*
- This is how the buffers are used. The arrows indicate the movement
- of data.
+ This is how the buffers are used. The arrows indicate data flow.
+
+-------+ wridx1++ +------+ rdidx1++ +----------+
| | <-------------- | buf1 | <-------------- | |
| | size1-- +------+ size1++ | |
again:
FD_ZERO(&rdfdset);
FD_ZERO(&wrfdset);
- if (!IS_INETD) {
- FD_SET(master_fd, &rdfdset);
- /* This is needed because free_session() does not
- * take into account master_fd when it finds new
- * maxfd among remaining fd's: */
- if (master_fd > maxfd)
- maxfd = master_fd;
- }
/* Select on the master socket, all telnet sockets and their
* ptys if there is room in their session buffers.
* NB: scalability problem: we recalculate entire bitmap
* before each select. Can be a problem with 500+ connections. */
- ts = sessions;
+ ts = G.sessions;
while (ts) {
- if (ts->size1 > 0) /* can write to pty */
- FD_SET(ts->ptyfd, &wrfdset);
- if (ts->size1 < BUFSIZE) /* can read from socket */
- FD_SET(ts->sockfd_read, &rdfdset);
- if (ts->size2 > 0) /* can write to socket */
- FD_SET(ts->sockfd_write, &wrfdset);
- if (ts->size2 < BUFSIZE) /* can read from pty */
- FD_SET(ts->ptyfd, &rdfdset);
- ts = ts->next;
+ struct tsession *next = ts->next; /* in case we free ts */
+ if (ts->shell_pid == -1) {
+ /* Child died and we detected that */
+ free_session(ts);
+ } else {
+ if (ts->size1 > 0) /* can write to pty */
+ FD_SET(ts->ptyfd, &wrfdset);
+ if (ts->size1 < BUFSIZE) /* can read from socket */
+ FD_SET(ts->sockfd_read, &rdfdset);
+ if (ts->size2 > 0) /* can write to socket */
+ FD_SET(ts->sockfd_write, &wrfdset);
+ if (ts->size2 < BUFSIZE) /* can read from pty */
+ FD_SET(ts->ptyfd, &rdfdset);
+ }
+ ts = next;
+ }
+ if (!IS_INETD) {
+ FD_SET(master_fd, &rdfdset);
+ /* This is needed because free_session() does not
+ * take master_fd into account when it finds new
+ * maxfd among remaining fd's */
+ if (master_fd > G.maxfd)
+ G.maxfd = master_fd;
}
- count = select(maxfd + 1, &rdfdset, &wrfdset, NULL, NULL);
+ {
+ struct timeval *tv_ptr = NULL;
+#if ENABLE_FEATURE_TELNETD_INETD_WAIT
+ struct timeval tv;
+ if ((opt & OPT_WAIT) && !G.sessions) {
+ tv.tv_sec = sec_linger;
+ tv.tv_usec = 0;
+ tv_ptr = &tv;
+ }
+#endif
+ count = select(G.maxfd + 1, &rdfdset, &wrfdset, NULL, tv_ptr);
+ }
+ if (count == 0) /* "telnetd -w SEC" timed out */
+ return 0;
if (count < 0)
goto again; /* EINTR or ENOMEM */
#if ENABLE_FEATURE_TELNETD_STANDALONE
- /* First check for and accept new sessions. */
+ /* Check for and accept new sessions */
if (!IS_INETD && FD_ISSET(master_fd, &rdfdset)) {
int fd;
struct tsession *new_ts;
fd = accept(master_fd, NULL, NULL);
if (fd < 0)
goto again;
- /* Create a new session and link it into our active list */
- new_ts = make_new_session(fd, fd);
+ close_on_exec_on(fd);
+
+ /* Create a new session and link it into active list */
+ new_ts = make_new_session(fd);
if (new_ts) {
- new_ts->next = sessions;
- sessions = new_ts;
+ new_ts->next = G.sessions;
+ G.sessions = new_ts;
} else {
close(fd);
}
}
#endif
- /* Then check for data tunneling. */
- ts = sessions;
+ /* Then check for data tunneling */
+ ts = G.sessions;
while (ts) { /* For all sessions... */
- struct tsession *next = ts->next; /* in case we free ts. */
+ struct tsession *next = ts->next; /* in case we free ts */
if (/*ts->size1 &&*/ FD_ISSET(ts->ptyfd, &wrfdset)) {
int num_totty;
unsigned char *ptr;
- /* Write to pty from buffer 1. */
+ /* Write to pty from buffer 1 */
ptr = remove_iacs(ts, &num_totty);
count = safe_write(ts->ptyfd, ptr, num_totty);
if (count < 0) {
if (errno == EAGAIN)
goto skip1;
- if (IS_INETD)
- return 0;
- free_session(ts);
- ts = next;
- continue;
+ goto kill_session;
}
ts->size1 -= count;
ts->wridx1 += count;
}
skip1:
if (/*ts->size2 &&*/ FD_ISSET(ts->sockfd_write, &wrfdset)) {
- /* Write to socket from buffer 2. */
+ /* Write to socket from buffer 2 */
count = MIN(BUFSIZE - ts->wridx2, ts->size2);
- count = safe_write(ts->sockfd_write, TS_BUF2 + ts->wridx2, count);
+ count = iac_safe_write(ts->sockfd_write, (void*)(TS_BUF2(ts) + ts->wridx2), count);
if (count < 0) {
if (errno == EAGAIN)
goto skip2;
- if (IS_INETD)
- return 0;
- free_session(ts);
- ts = next;
- continue;
+ goto kill_session;
}
ts->size2 -= count;
ts->wridx2 += count;
/* Should not be needed, but... remove_iacs is actually buggy
* (it cannot process iacs which wrap around buffer's end)!
* Since properly fixing it requires writing bigger code,
- * we will rely instead on this code making it virtually impossible
+ * we rely instead on this code making it virtually impossible
* to have wrapped iac (people don't type at 2k/second).
* It also allows for bigger reads in common case. */
if (ts->size1 == 0) {
}
if (/*ts->size1 < BUFSIZE &&*/ FD_ISSET(ts->sockfd_read, &rdfdset)) {
- /* Read from socket to buffer 1. */
+ /* Read from socket to buffer 1 */
count = MIN(BUFSIZE - ts->rdidx1, BUFSIZE - ts->size1);
- count = safe_read(ts->sockfd_read, TS_BUF1 + ts->rdidx1, count);
+ count = safe_read(ts->sockfd_read, TS_BUF1(ts) + ts->rdidx1, count);
if (count <= 0) {
if (count < 0 && errno == EAGAIN)
goto skip3;
- if (IS_INETD)
- return 0;
- free_session(ts);
- ts = next;
- continue;
+ goto kill_session;
}
/* Ignore trailing NUL if it is there */
- if (!TS_BUF1[ts->rdidx1 + count - 1]) {
- if (!--count)
- goto skip3;
+ if (!TS_BUF1(ts)[ts->rdidx1 + count - 1]) {
+ --count;
}
ts->size1 += count;
ts->rdidx1 += count;
}
skip3:
if (/*ts->size2 < BUFSIZE &&*/ FD_ISSET(ts->ptyfd, &rdfdset)) {
- /* Read from pty to buffer 2. */
+ /* Read from pty to buffer 2 */
count = MIN(BUFSIZE - ts->rdidx2, BUFSIZE - ts->size2);
- count = safe_read(ts->ptyfd, TS_BUF2 + ts->rdidx2, count);
+ count = safe_read(ts->ptyfd, TS_BUF2(ts) + ts->rdidx2, count);
if (count <= 0) {
if (count < 0 && errno == EAGAIN)
goto skip4;
- if (IS_INETD)
- return 0;
- free_session(ts);
- ts = next;
- continue;
+ goto kill_session;
}
ts->size2 += count;
ts->rdidx2 += count;
}
skip4:
ts = next;
+ continue;
+ kill_session:
+ free_session(ts);
+ ts = next;
}
+
goto again;
}
projects / oweals / busybox.git / blobdiff