* Simple telnet server
* Bjorn Wesen, Axis Communications AB (bjornw@axis.com)
*
- * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
*
* ---------------------------------------------------------------------------
* (C) Copyright 2000, Axis Communications AB, LUND, SWEDEN
*
* 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
*/
+//usage:#define telnetd_trivial_usage
+//usage: "[OPTIONS]"
+//usage:#define telnetd_full_usage "\n\n"
+//usage: "Handle incoming telnet connections"
+//usage: IF_NOT_FEATURE_TELNETD_STANDALONE(" via inetd") "\n"
+//usage: "\n -l LOGIN Exec LOGIN on connect"
+//usage: "\n -f ISSUE_FILE Display ISSUE_FILE instead of /etc/issue"
+//usage: "\n -K Close connection as soon as login exits"
+//usage: "\n (normally wait until all programs close slave pty)"
+//usage: IF_FEATURE_TELNETD_STANDALONE(
+//usage: "\n -p PORT Port to listen on"
+//usage: "\n -b ADDR[:PORT] Address to bind to"
+//usage: "\n -F Run in foreground"
+//usage: "\n -i Inetd mode"
+//usage: IF_FEATURE_TELNETD_INETD_WAIT(
+//usage: "\n -w SEC Inetd 'wait' mode, linger time SEC"
+//usage: "\n -S Log to syslog (implied by -i or without -F and -w)"
+//usage: )
+//usage: )
+
#define DEBUG 0
#include "libbb.h"
#include <syslog.h>
#if DEBUG
-#define TELCMDS
-#define TELOPTS
+# define TELCMDS
+# define TELOPTS
#endif
#include <arpa/telnet.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;
-static const char *loginpath = "/bin/login";
-static const char *issuefile = "/etc/issue.net";
+struct globals {
+ struct tsession *sessions;
+ const char *loginpath;
+ const char *issuefile;
+ int maxfd;
+} FIX_ALIASING;
+#define G (*(struct globals*)&bb_common_bufsiz1)
+#define INIT_G() do { \
+ G.loginpath = "/bin/login"; \
+ G.issuefile = "/etc/issue.net"; \
+} while (0)
/*
string of characters fit for the terminal. Do this by packing
all characters meant for the terminal sequentially towards the end of buf.
- Return a pointer to the beginning of the characters meant for the terminal.
+ Return a pointer to the beginning of the characters meant for the terminal
and make *num_totty the number of characters that should be sent to
the terminal.
- Note - If an IAC (3 byte quantity) starts before (bf + len) but extends
+ Note - if an IAC (3 byte quantity) starts before (bf + len) but extends
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.
+ * See RFC 1123 3.3.1 Telnet End-of-Line Convention.
*/
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;
*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);
}
+/*
+ * Converting single IAC into double on output
+ */
+static size_t iac_safe_write(int fd, const char *buf, size_t count)
+{
+ 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;
+ }
+ /* 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;
+ }
+ /* 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)
- SKIP_FEATURE_TELNETD_STANDALONE(void)
+ IF_FEATURE_TELNETD_STANDALONE(int sock)
+ IF_NOT_FEATURE_TELNETD_STANDALONE(void)
) {
+#if !ENABLE_FEATURE_TELNETD_STANDALONE
+ enum { sock = 0 };
+#endif
const char *login_argv[2];
struct termios termbuf;
int fd, pid;
/*ts->buf1 = (char *)(ts + 1);*/
/*ts->buf2 = ts->buf1 + BUFSIZE;*/
- /* Got a new connection, set up a tty. */
- fd = getpty(tty_name);
- 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);
+
+ /* SO_KEEPALIVE by popular demand */
+ setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, &const_int_1, sizeof(const_int_1));
#if ENABLE_FEATURE_TELNETD_STANDALONE
ts->sockfd_read = sock;
ndelay_on(sock);
- if (!sock) { /* We are called with fd 0 - we are in inetd mode */
+ 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 > maxfd)
- maxfd = sock;
+ if (sock > G.maxfd)
+ G.maxfd = sock;
#else
/* 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);
/* Child */
/* Careful - we are after vfork! */
- /* make new session and process group */
- setsid();
-
- /* Restore default signal handling */
+ /* Restore default signal handling ASAP */
bb_signals((1 << SIGCHLD) + (1 << SIGPIPE), SIG_DFL);
- /* open the child's side of the tty. */
+ pid = getpid();
+
+ if (ENABLE_FEATURE_UTMP) {
+ len_and_sockaddr *lsa = get_peer_lsa(sock);
+ char *hostname = NULL;
+ if (lsa) {
+ hostname = xmalloc_sockaddr2dotted(&lsa->u.sa);
+ free(lsa);
+ }
+ write_new_utmp(pid, LOGIN_PROCESS, tty_name, /*username:*/ "LOGIN", hostname);
+ free(hostname);
+ }
+
+ /* Make new session and process group */
+ setsid();
+
+ /* 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--);
- 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)). */
+ close(0);
+ xopen(tty_name, O_RDWR); /* becomes our ctty */
+ xdup2(0, 1);
+ xdup2(0, 2);
+ tcsetpgrp(0, pid); /* 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)) */
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,
* (parent is supposed to read it, but parent waits
* for vforked child to exec!) */
- print_login_issue(issuefile, NULL);
+ print_login_issue(G.issuefile, tty_name);
/* Exec shell / login / whatever */
- login_argv[0] = loginpath;
+ login_argv[0] = G.loginpath;
login_argv[1] = NULL;
/* exec busybox applet (if PREFER_APPLETS=y), if that fails,
- * exec external program */
- BB_EXECVP(loginpath, (char **)login_argv);
+ * 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(1); /*bb_perror_msg_and_die("execv %s", loginpath);*/
+ _exit(EXIT_FAILURE); /*bb_perror_msg_and_die("execv %s", G.loginpath);*/
}
-/* 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 */
- OPT_FOREGROUND = (1 << 6) * ENABLE_FEATURE_TELNETD_STANDALONE, /* -F */
-};
-
#if ENABLE_FEATURE_TELNETD_STANDALONE
static void
free_session(struct tsession *ts)
{
- struct tsession *t = sessions;
+ struct tsession *t;
if (option_mask32 & OPT_INETD)
- exit(0);
+ exit(EXIT_SUCCESS);
/* Unlink this telnet session from the session list */
+ t = G.sessions;
if (t == ts)
- sessions = ts->next;
+ G.sessions = ts->next;
else {
while (t->next != ts)
t = t->next;
* 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);
+ waitpid(ts->shell_pid, NULL, 0);
#endif
close(ts->ptyfd);
close(ts->sockfd_read);
free(ts);
/* Scan all sessions and find new maxfd */
- maxfd = 0;
- ts = sessions;
+ 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 (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 (maxfd < ts->sockfd_write)
- maxfd = ts->sockfd_write;
+ if (G.maxfd < ts->sockfd_write)
+ G.maxfd = ts->sockfd_write;
#endif
ts = ts->next;
}
#else /* !FEATURE_TELNETD_STANDALONE */
-/* Used in main() only, thus "return 0" actually is exit(0). */
+/* 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 ATTRIBUTE_UNUSED)
+static void handle_sigchld(int sig UNUSED_PARAM)
{
pid_t pid;
struct tsession *ts;
+ int save_errno = errno;
/* Looping: more than one child may have exited */
while (1) {
pid = wait_any_nohang(NULL);
if (pid <= 0)
break;
- ts = sessions;
+ ts = G.sessions;
while (ts) {
if (ts->shell_pid == pid) {
ts->shell_pid = -1;
+// man utmp:
+// When init(8) finds that a process has exited, it locates its utmp entry
+// by ut_pid, sets ut_type to DEAD_PROCESS, and clears ut_user, ut_host
+// and ut_time with null bytes.
+// [same applies to other processes which maintain utmp entries, like telnetd]
+//
+// We do not bother actually clearing fields:
+// it might be interesting to know who was logged in and from where
+ update_utmp(pid, DEAD_PROCESS, /*tty_name:*/ NULL, /*username:*/ NULL, /*hostname:*/ NULL);
break;
}
ts = ts->next;
}
}
+
+ errno = save_errno;
}
int telnetd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
-int telnetd_main(int argc ATTRIBUTE_UNUSED, 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
+ INIT_G();
+
+ /* -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:Ki" 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 */
}
}
/* 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;
}
- USE_FEATURE_TELNETD_STANDALONE(
- if (opt & OPT_PORT)
- portnbr = xatou16(opt_portnbr);
- );
-
- /* 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);
- 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 {
- master_fd = create_and_bind_stream_or_die(opt_bindaddr, portnbr);
- xlisten(master_fd, 1);
+ 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(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++ | |
* 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) {
- struct tsession *next = ts->next; /* in case we free ts. */
+ struct tsession *next = ts->next; /* in case we free ts */
if (ts->shell_pid == -1) {
/* Child died and we detected that */
free_session(ts);
/* 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 > maxfd)
- maxfd = master_fd;
+ 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 */
+ 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) {
}
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 (/*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;
goto kill_session;
}
/* Ignore trailing NUL if it is there */
- if (!TS_BUF1[ts->rdidx1 + count - 1]) {
+ if (!TS_BUF1(ts)[ts->rdidx1 + count - 1]) {
--count;
}
ts->size1 += 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;
ts = next;
continue;
kill_session:
+ if (ts->shell_pid > 0)
+ update_utmp(ts->shell_pid, DEAD_PROCESS, /*tty_name:*/ NULL, /*username:*/ NULL, /*hostname:*/ NULL);
free_session(ts);
ts = next;
}