-/* $Id: telnetd.c,v 1.7 2003/09/02 02:36:16 bug1 Exp $
- *
+/* vi: set sw=4 ts=4: */
+/*
* Simple telnet server
* Bjorn Wesen, Axis Communications AB (bjornw@axis.com)
*
- * This file is distributed under the Gnu Public License (GPL),
- * please see the file LICENSE for further information.
+ * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*
* ---------------------------------------------------------------------------
* (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
*/
-/*#define DEBUG 1 */
-
-#include <sys/time.h>
-#include <sys/socket.h>
-#include <sys/wait.h>
-#include <string.h>
-#include <stdlib.h>
-#include <unistd.h>
-#include <errno.h>
-#include <netinet/in.h>
-#include <fcntl.h>
-#include <stdio.h>
-#include <signal.h>
-#include <termios.h>
-#ifdef DEBUG
+#define DEBUG 0
+
+#include "libbb.h"
+#include <syslog.h>
+
+#if DEBUG
#define TELCMDS
#define TELOPTS
#endif
#include <arpa/telnet.h>
-#include <ctype.h>
-#include <sys/syslog.h>
-
-#include "busybox.h"
-
-#define BUFSIZE 4000
-
-static const char *loginpath =
-#ifdef CONFIG_LOGIN
-"/bin/login";
-#else
-DEFAULT_SHELL;
-#endif
-static const char *issuefile = "/etc/issue.net";
-
-/* shell name and arguments */
-
-static const char *argv_init[] = {NULL, NULL};
-
-/* structure that describes a session */
struct tsession {
-#ifdef CONFIG_FEATURE_TELNETD_INETD
- int sockfd_read, sockfd_write, ptyfd;
-#else /* CONFIG_FEATURE_TELNETD_INETD */
struct tsession *next;
- int sockfd, ptyfd;
-#endif /* CONFIG_FEATURE_TELNETD_INETD */
- int shell_pid;
+ pid_t shell_pid;
+ int sockfd_read;
+ int sockfd_write;
+ int ptyfd;
+
/* two circular buffers */
- char *buf1, *buf2;
+ /*char *buf1, *buf2;*/
+/*#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;
};
-/*
-
- This is how the buffers are used. The arrows indicate the movement
- of data.
-
- +-------+ wridx1++ +------+ rdidx1++ +----------+
- | | <-------------- | buf1 | <-------------- | |
- | | size1-- +------+ size1++ | |
- | pty | | socket |
- | | rdidx2++ +------+ wridx2++ | |
- | | --------------> | buf2 | --------------> | |
- +-------+ size2++ +------+ size2-- +----------+
-
- Each session has got two buffers.
-
-*/
+/* Two buffers are directly after tsession in malloced memory.
+ * Make whole thing fit in 4k */
+enum { BUFSIZE = (4 * 1024 - sizeof(struct tsession)) / 2 };
-static int maxfd;
-static struct tsession *sessions;
+/* Globals */
+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)
/*
-
- Remove all IAC's from the buffer pointed to by bf (recieved IACs are ignored
- and must be removed so as to not be interpreted by the terminal). Make an
- uninterrupted string of characters fit for the terminal. Do this by packing
- all characters meant for the terminal sequentially towards the end of bf.
+ Remove all IAC's from buf1 (received IACs are ignored and must be removed
+ so as to not be interpreted by the terminal). Make an uninterrupted
+ 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.
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
- past (bf + len) then that IAC will be left unprocessed and *processed will be
- less than len.
+ 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.
- */
-static char *
-remove_iacs(struct tsession *ts, int *pnum_totty) {
- unsigned char *ptr0 = ts->buf1 + ts->wridx1;
+ 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) + ts->wridx1;
unsigned char *ptr = ptr0;
unsigned char *totty = ptr;
unsigned char *end = ptr + MIN(BUFSIZE - ts->wridx1, ts->size1);
- int processed;
int num_totty;
while (ptr < end) {
if (*ptr != IAC) {
- *totty++ = *ptr++;
+ char c = *ptr;
+
+ *totty++ = c;
+ ptr++;
+ /* 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++;
+ continue;
}
- else {
- if ((ptr+2) < end) {
- /* the entire IAC is contained in the buffer
- we were asked to process. */
-#ifdef DEBUG
- fprintf(stderr, "Ignoring IAC %s,%s\n",
- *ptr, TELCMD(*(ptr+1)), TELOPT(*(ptr+2)));
-#endif
- ptr += 3;
- } else {
- /* only the beginning of the IAC is in the
- buffer we were asked to process, we can't
- process this char. */
- break;
- }
+
+ 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]));
+#endif
+ ptr += 3;
}
- processed = ptr - ptr0;
num_totty = totty - ptr0;
- /* the difference between processed and num_to tty
- is all the iacs we removed from the stream.
- Adjust buf1 accordingly. */
- ts->wridx1 += processed - num_totty;
- ts->size1 -= processed - num_totty;
*pnum_totty = num_totty;
- /* move the chars meant for the terminal towards the end of the
- buffer. */
+ /* 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 */
return memmove(ptr - num_totty, ptr0, num_totty);
}
-
-static int
-getpty(char *line)
+/*
+ * Converting single IAC into double on output
+ */
+static size_t iac_safe_write(int fd, const char *buf, size_t count)
{
- int p;
-#ifdef CONFIG_FEATURE_DEVPTS
- p = open("/dev/ptmx", 2);
- if (p > 0) {
- grantpt(p);
- unlockpt(p);
- strcpy(line, ptsname(p));
- 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 ((p = open(line, O_RDWR | O_NOCTTY)) >= 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 /* CONFIG_FEATURE_DEVPTS */
- return -1;
-}
-
-
-static void
-send_iac(struct tsession *ts, unsigned char command, int option)
-{
- /* We rely on that there is space in the buffer for now. */
- char *b = ts->buf2 + ts->rdidx2;
- *b++ = IAC;
- *b++ = command;
- *b++ = option;
- ts->rdidx2 += 3;
- ts->size2 += 3;
+ /* 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 *
-#ifdef CONFIG_FEATURE_TELNETD_INETD
-make_new_session(void)
-#else /* CONFIG_FEATURE_TELNETD_INETD */
-make_new_session(int sockfd)
-#endif /* CONFIG_FEATURE_TELNETD_INETD */
-{
+make_new_session(
+ IF_FEATURE_TELNETD_STANDALONE(int sock)
+ IF_NOT_FEATURE_TELNETD_STANDALONE(void)
+) {
+ const char *login_argv[2];
struct termios termbuf;
- int pty, pid;
- char tty_name[32];
- struct tsession *ts = malloc(sizeof(struct tsession) + BUFSIZE * 2);
-
- ts->buf1 = (char *)(&ts[1]);
- ts->buf2 = ts->buf1 + BUFSIZE;
-
-#ifdef CONFIG_FEATURE_TELNETD_INETD
- ts->sockfd_read = 0;
- ts->sockfd_write = 1;
-#else /* CONFIG_FEATURE_TELNETD_INETD */
- ts->sockfd = sockfd;
-#endif /* CONFIG_FEATURE_TELNETD_INETD */
-
- ts->rdidx1 = ts->wridx1 = ts->size1 = 0;
- ts->rdidx2 = ts->wridx2 = ts->size2 = 0;
-
- /* Got a new connection, set up a tty and spawn a shell. */
-
- pty = getpty(tty_name);
-
- if (pty < 0) {
- syslog_msg(LOG_USER, LOG_ERR, "All network ports in use!");
- return 0;
+ int fd, pid;
+ 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 = 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
+ /* 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);
}
-
- if (pty > maxfd)
- maxfd = pty;
-
- ts->ptyfd = pty;
+ ts->sockfd_write = sock;
+ if (sock > G.maxfd)
+ G.maxfd = sock;
+#else
+ /* 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
- * stuff that requires char-by-char support.
- */
-
- send_iac(ts, DO, TELOPT_ECHO);
- send_iac(ts, DO, TELOPT_LFLOW);
- send_iac(ts, WILL, TELOPT_ECHO);
- send_iac(ts, WILL, TELOPT_SGA);
-
-
- if ((pid = fork()) < 0) {
- syslog_msg(LOG_USER, LOG_ERR, "Can`t forking");
+ * stuff that requires char-by-char support. */
+ {
+ static const char iacs_to_send[] ALIGN1 = {
+ IAC, DO, TELOPT_ECHO,
+ IAC, DO, TELOPT_NAWS,
+ /* This requires telnetd.ctrlSQ.patch (incomplete) */
+ /* IAC, DO, TELOPT_LFLOW, */
+ IAC, WILL, TELOPT_ECHO,
+ IAC, WILL, TELOPT_SGA
+ };
+ /* 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;*/
}
- if (pid == 0) {
- /* In child, open the child's side of the tty. */
- int i;
-
- for(i = 0; i <= maxfd; i++)
- close(i);
- /* make new process group */
- setsid();
-
- if (open(tty_name, O_RDWR /*| O_NOCTTY*/) < 0) {
- syslog_msg(LOG_USER, LOG_ERR, "Could not open tty");
- exit(1);
- }
- dup(0);
- dup(0);
-
- tcsetpgrp(0, getpid());
-
- /* 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);
-
- print_login_issue(issuefile, NULL);
-
- /* exec shell, with correct argv and env */
- execv(loginpath, (char *const *)argv_init);
-
- /* NOT REACHED */
- syslog_msg(LOG_USER, LOG_ERR, "execv error");
- exit(1);
+ fflush_all();
+ pid = vfork(); /* NOMMU-friendly */
+ if (pid < 0) {
+ free(ts);
+ close(fd);
+ /* sock will be closed by caller */
+ bb_perror_msg("vfork");
+ return NULL;
+ }
+ if (pid > 0) {
+ /* Parent */
+ ts->shell_pid = pid;
+ return ts;
}
- ts->shell_pid = pid;
-
- return ts;
+ /* Child */
+ /* Careful - we are after vfork! */
+
+ /* 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 */
+ /* NB: setsid() disconnects from any previous ctty's. Therefore
+ * we must open child's side of the tty AFTER setsid! */
+ 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)) */
+ 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_stdin_TCSANOW(&termbuf);
+
+ /* 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(G.issuefile, tty_name);
+
+ /* Exec shell / login / whatever */
+ login_argv[0] = G.loginpath;
+ login_argv[1] = NULL;
+ /* 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);*/
}
-#ifndef CONFIG_FEATURE_TELNETD_INETD
+#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;
+ /* Unlink this telnet session from the session list */
+ if (t == ts)
+ G.sessions = ts->next;
else {
- while(t->next != ts)
+ 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);
-
+ waitpid(ts->shell_pid, NULL, 0);
+#endif
close(ts->ptyfd);
- close(ts->sockfd);
-
- if(ts->ptyfd == maxfd || ts->sockfd == maxfd)
- maxfd--;
- if(ts->ptyfd == maxfd || ts->sockfd == maxfd)
- maxfd--;
-
+ close(ts->sockfd_read);
+ /* 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);
-}
-#endif /* CONFIG_FEATURE_TELNETD_INETD */
-int
-telnetd_main(int argc, char **argv)
-{
-#ifndef CONFIG_FEATURE_TELNETD_INETD
- struct sockaddr_in sa;
- int master_fd;
-#endif /* CONFIG_FEATURE_TELNETD_INETD */
- fd_set rdfdset, wrfdset;
- int selret;
-#ifndef CONFIG_FEATURE_TELNETD_INETD
- int on = 1;
- int portnbr = 23;
-#endif /* CONFIG_FEATURE_TELNETD_INETD */
- int c;
- static const char options[] =
-#ifdef CONFIG_FEATURE_TELNETD_INETD
- "f:l:";
-#else /* CONFIG_EATURE_TELNETD_INETD */
- "f:l:p:";
-#endif /* CONFIG_FEATURE_TELNETD_INETD */
- int maxlen, w, r;
-
- for (;;) {
- c = getopt( argc, argv, options);
- if (c == EOF) break;
- switch (c) {
- case 'f':
- issuefile = strdup (optarg);
- break;
- case 'l':
- loginpath = strdup (optarg);
- break;
-#ifndef CONFIG_FEATURE_TELNETD_INETD
- case 'p':
- portnbr = atoi(optarg);
- break;
-#endif /* CONFIG_FEATURE_TELNETD_INETD */
- default:
- bb_show_usage();
- }
+ /* Scan all sessions and find new maxfd */
+ G.maxfd = 0;
+ ts = G.sessions;
+ while (ts) {
+ 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;
}
+}
- if (access(loginpath, X_OK) < 0) {
- bb_error_msg_and_die ("'%s' unavailable.", loginpath);
- }
+#else /* !FEATURE_TELNETD_STANDALONE */
- argv_init[0] = loginpath;
+/* Used in main() only, thus "return 0" actually is exit(EXIT_SUCCESS). */
+#define free_session(ts) return 0
-#ifdef CONFIG_FEATURE_TELNETD_INETD
- maxfd = 1;
- sessions = make_new_session();
-#else /* CONFIG_EATURE_TELNETD_INETD */
- sessions = 0;
+#endif
- /* Grab a TCP socket. */
+static void handle_sigchld(int sig UNUSED_PARAM)
+{
+ pid_t pid;
+ struct tsession *ts;
- master_fd = socket(AF_INET, SOCK_STREAM, 0);
- if (master_fd < 0) {
- bb_perror_msg_and_die("socket");
+ /* 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;
+ }
}
- (void)setsockopt(master_fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
-
- /* Set it to listen to specified port. */
-
- memset((void *)&sa, 0, sizeof(sa));
- sa.sin_family = AF_INET;
- sa.sin_port = htons(portnbr);
+}
- if (bind(master_fd, (struct sockaddr *) &sa, sizeof(sa)) < 0) {
- bb_perror_msg_and_die("bind");
+int telnetd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int telnetd_main(int argc UNUSED_PARAM, char **argv)
+{
+ fd_set rdfdset, wrfdset;
+ unsigned opt;
+ int count;
+ struct tsession *ts;
+#if ENABLE_FEATURE_TELNETD_STANDALONE
+#define IS_INETD (opt & OPT_INETD)
+ 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,
+ };
+#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"
+ 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);
+ }
}
-
- if (listen(master_fd, 1) < 0) {
- bb_perror_msg_and_die("listen");
+ /* Redirect log to syslog early, if needed */
+ if (IS_INETD || (opt & OPT_SYSLOG) || !(opt & OPT_FOREGROUND)) {
+ openlog(applet_name, LOG_PID, LOG_DAEMON);
+ logmode = LOGMODE_SYSLOG;
}
+#if ENABLE_FEATURE_TELNETD_STANDALONE
+ if (IS_INETD) {
+ 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 = 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
+ G.sessions = make_new_session();
+ if (!G.sessions) /* pty opening or vfork problem, exit */
+ return 1; /* make_new_session printed error message */
+#endif
- if (daemon(0, 0) < 0)
- bb_perror_msg_and_die("daemon");
-
+ /* We don't want to die if just one session is broken */
+ signal(SIGPIPE, SIG_IGN);
- maxfd = master_fd;
-#endif /* CONFIG_FEATURE_TELNETD_INETD */
+ if (opt & OPT_WATCHCHILD)
+ signal(SIGCHLD, handle_sigchld);
+ else /* prevent dead children from becoming zombies */
+ signal(SIGCHLD, SIG_IGN);
- do {
- struct tsession *ts;
+/*
+ This is how the buffers are used. The arrows indicate data flow.
- FD_ZERO(&rdfdset);
- FD_ZERO(&wrfdset);
+ +-------+ wridx1++ +------+ rdidx1++ +----------+
+ | | <-------------- | buf1 | <-------------- | |
+ | | size1-- +------+ size1++ | |
+ | pty | | socket |
+ | | rdidx2++ +------+ wridx2++ | |
+ | | --------------> | buf2 | --------------> | |
+ +-------+ size2++ +------+ size2-- +----------+
- /* select on the master socket, all telnet sockets and their
- * ptys if there is room in their respective session buffers.
- */
+ size1: "how many bytes are buffered for pty between rdidx1 and wridx1?"
+ size2: "how many bytes are buffered for socket between rdidx2 and wridx2?"
-#ifndef CONFIG_FEATURE_TELNETD_INETD
+ Each session has got two buffers. Buffers are circular. If sizeN == 0,
+ buffer is empty. If sizeN == BUFSIZE, buffer is full. In both these cases
+ rdidxN == wridxN.
+*/
+ again:
+ FD_ZERO(&rdfdset);
+ FD_ZERO(&wrfdset);
+
+ /* 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 = G.sessions;
+ while (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);
+ } 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);
-#endif /* CONFIG_FEATURE_TELNETD_INETD */
+ /* 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;
+ }
- ts = sessions;
-#ifndef CONFIG_FEATURE_TELNETD_INETD
- while (ts) {
-#endif /* CONFIG_FEATURE_TELNETD_INETD */
- /* buf1 is used from socket to pty
- * buf2 is used from pty to socket
- */
- if (ts->size1 > 0) {
- FD_SET(ts->ptyfd, &wrfdset); /* can write to pty */
- }
- if (ts->size1 < BUFSIZE) {
-#ifdef CONFIG_FEATURE_TELNETD_INETD
- FD_SET(ts->sockfd_read, &rdfdset); /* can read from socket */
-#else /* CONFIG_FEATURE_TELNETD_INETD */
- FD_SET(ts->sockfd, &rdfdset); /* can read from socket */
-#endif /* CONFIG_FEATURE_TELNETD_INETD */
- }
- if (ts->size2 > 0) {
-#ifdef CONFIG_FEATURE_TELNETD_INETD
- FD_SET(ts->sockfd_write, &wrfdset); /* can write to socket */
-#else /* CONFIG_FEATURE_TELNETD_INETD */
- FD_SET(ts->sockfd, &wrfdset); /* can write to socket */
-#endif /* CONFIG_FEATURE_TELNETD_INETD */
- }
- if (ts->size2 < BUFSIZE) {
- FD_SET(ts->ptyfd, &rdfdset); /* can read from pty */
- }
-#ifndef CONFIG_FEATURE_TELNETD_INETD
- ts = ts->next;
+ {
+ 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 /* CONFIG_FEATURE_TELNETD_INETD */
-
- selret = select(maxfd + 1, &rdfdset, &wrfdset, 0, 0);
-
- if (!selret)
- break;
-
-#ifndef CONFIG_FEATURE_TELNETD_INETD
- /* First check for and accept new sessions. */
- if (FD_ISSET(master_fd, &rdfdset)) {
- int fd, salen;
-
- salen = sizeof(sa);
- if ((fd = accept(master_fd, (struct sockaddr *)&sa,
- &salen)) < 0) {
- continue;
- } else {
- /* Create a new session and link it into
- our active list. */
- struct tsession *new_ts = make_new_session(fd);
- if (new_ts) {
- new_ts->next = sessions;
- sessions = new_ts;
- if (fd > maxfd)
- maxfd = fd;
- } else {
- close(fd);
- }
- }
+#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
+ /* 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;
+ 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 = G.sessions;
+ G.sessions = new_ts;
+ } else {
+ close(fd);
}
+ }
+#endif
- /* Then check for data tunneling. */
-
- ts = sessions;
- while (ts) { /* For all sessions... */
-#endif /* CONFIG_FEATURE_TELNETD_INETD */
-#ifndef CONFIG_FEATURE_TELNETD_INETD
- struct tsession *next = ts->next; /* in case we free ts. */
-#endif /* CONFIG_FEATURE_TELNETD_INETD */
-
- if (ts->size1 && FD_ISSET(ts->ptyfd, &wrfdset)) {
- int num_totty;
- char *ptr;
- /* Write to pty from buffer 1. */
-
- ptr = remove_iacs(ts, &num_totty);
-
- w = write(ts->ptyfd, ptr, num_totty);
- if (w < 0) {
-#ifdef CONFIG_FEATURE_TELNETD_INETD
- exit(0);
-#else /* CONFIG_FEATURE_TELNETD_INETD */
- free_session(ts);
- ts = next;
- continue;
-#endif /* CONFIG_FEATURE_TELNETD_INETD */
- }
- ts->wridx1 += w;
- ts->size1 -= w;
- if (ts->wridx1 == BUFSIZE)
- ts->wridx1 = 0;
+ /* Then check for data tunneling */
+ ts = G.sessions;
+ while (ts) { /* For all sessions... */
+ 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 */
+ ptr = remove_iacs(ts, &num_totty);
+ count = safe_write(ts->ptyfd, ptr, num_totty);
+ if (count < 0) {
+ if (errno == EAGAIN)
+ goto skip1;
+ goto kill_session;
}
-
-#ifdef CONFIG_FEATURE_TELNETD_INETD
- if (ts->size2 && FD_ISSET(ts->sockfd_write, &wrfdset)) {
-#else /* CONFIG_FEATURE_TELNETD_INETD */
- if (ts->size2 && FD_ISSET(ts->sockfd, &wrfdset)) {
-#endif /* CONFIG_FEATURE_TELNETD_INETD */
- /* Write to socket from buffer 2. */
- maxlen = MIN(BUFSIZE - ts->wridx2, ts->size2);
-#ifdef CONFIG_FEATURE_TELNETD_INETD
- w = write(ts->sockfd_write, ts->buf2 + ts->wridx2, maxlen);
- if (w < 0)
- exit(0);
-#else /* CONFIG_FEATURE_TELNETD_INETD */
- w = write(ts->sockfd, ts->buf2 + ts->wridx2, maxlen);
- if (w < 0) {
- free_session(ts);
- ts = next;
- continue;
- }
-#endif /* CONFIG_FEATURE_TELNETD_INETD */
- ts->wridx2 += w;
- ts->size2 -= w;
- if (ts->wridx2 == BUFSIZE)
- ts->wridx2 = 0;
+ ts->size1 -= count;
+ ts->wridx1 += count;
+ if (ts->wridx1 >= BUFSIZE) /* actually == BUFSIZE */
+ ts->wridx1 = 0;
+ }
+ skip1:
+ if (/*ts->size2 &&*/ FD_ISSET(ts->sockfd_write, &wrfdset)) {
+ /* Write to socket from buffer 2 */
+ count = MIN(BUFSIZE - ts->wridx2, ts->size2);
+ count = iac_safe_write(ts->sockfd_write, (void*)(TS_BUF2(ts) + ts->wridx2), count);
+ if (count < 0) {
+ if (errno == EAGAIN)
+ goto skip2;
+ goto kill_session;
}
+ ts->size2 -= count;
+ ts->wridx2 += count;
+ if (ts->wridx2 >= BUFSIZE) /* actually == BUFSIZE */
+ ts->wridx2 = 0;
+ }
+ skip2:
+ /* 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 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) {
+ ts->rdidx1 = 0;
+ ts->wridx1 = 0;
+ }
+ if (ts->size2 == 0) {
+ ts->rdidx2 = 0;
+ ts->wridx2 = 0;
+ }
-#ifdef CONFIG_FEATURE_TELNETD_INETD
- if (ts->size1 < BUFSIZE && FD_ISSET(ts->sockfd_read, &rdfdset)) {
-#else /* CONFIG_FEATURE_TELNETD_INETD */
- if (ts->size1 < BUFSIZE && FD_ISSET(ts->sockfd, &rdfdset)) {
-#endif /* CONFIG_FEATURE_TELNETD_INETD */
- /* Read from socket to buffer 1. */
- maxlen = MIN(BUFSIZE - ts->rdidx1,
- BUFSIZE - ts->size1);
-#ifdef CONFIG_FEATURE_TELNETD_INETD
- r = read(ts->sockfd_read, ts->buf1 + ts->rdidx1, maxlen);
- if (!r || (r < 0 && errno != EINTR))
- exit(0);
-#else /* CONFIG_FEATURE_TELNETD_INETD */
- r = read(ts->sockfd, ts->buf1 + ts->rdidx1, maxlen);
- if (!r || (r < 0 && errno != EINTR)) {
- free_session(ts);
- ts = next;
- continue;
- }
-#endif /* CONFIG_FEATURE_TELNETD_INETD */
- if(!*(ts->buf1 + ts->rdidx1 + r - 1)) {
- r--;
- if(!r)
- continue;
- }
- ts->rdidx1 += r;
- ts->size1 += r;
- if (ts->rdidx1 == BUFSIZE)
- ts->rdidx1 = 0;
+ if (/*ts->size1 < BUFSIZE &&*/ FD_ISSET(ts->sockfd_read, &rdfdset)) {
+ /* Read from socket to buffer 1 */
+ count = MIN(BUFSIZE - ts->rdidx1, BUFSIZE - ts->size1);
+ 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;
}
-
- if (ts->size2 < BUFSIZE && FD_ISSET(ts->ptyfd, &rdfdset)) {
- /* Read from pty to buffer 2. */
- maxlen = MIN(BUFSIZE - ts->rdidx2,
- BUFSIZE - ts->size2);
- r = read(ts->ptyfd, ts->buf2 + ts->rdidx2, maxlen);
- if (!r || (r < 0 && errno != EINTR)) {
-#ifdef CONFIG_FEATURE_TELNETD_INETD
- exit(0);
-#else /* CONFIG_FEATURE_TELNETD_INETD */
- free_session(ts);
- ts = next;
- continue;
-#endif /* CONFIG_FEATURE_TELNETD_INETD */
- }
- ts->rdidx2 += r;
- ts->size2 += r;
- if (ts->rdidx2 == BUFSIZE)
- ts->rdidx2 = 0;
+ /* Ignore trailing NUL if it is there */
+ if (!TS_BUF1(ts)[ts->rdidx1 + count - 1]) {
+ --count;
}
-
- if (ts->size1 == 0) {
+ ts->size1 += count;
+ ts->rdidx1 += count;
+ if (ts->rdidx1 >= BUFSIZE) /* actually == BUFSIZE */
ts->rdidx1 = 0;
- ts->wridx1 = 0;
+ }
+ skip3:
+ if (/*ts->size2 < BUFSIZE &&*/ FD_ISSET(ts->ptyfd, &rdfdset)) {
+ /* Read from pty to buffer 2 */
+ count = MIN(BUFSIZE - ts->rdidx2, BUFSIZE - ts->size2);
+ count = safe_read(ts->ptyfd, TS_BUF2(ts) + ts->rdidx2, count);
+ if (count <= 0) {
+ if (count < 0 && errno == EAGAIN)
+ goto skip4;
+ goto kill_session;
}
- if (ts->size2 == 0) {
+ ts->size2 += count;
+ ts->rdidx2 += count;
+ if (ts->rdidx2 >= BUFSIZE) /* actually == BUFSIZE */
ts->rdidx2 = 0;
- ts->wridx2 = 0;
- }
-#ifndef CONFIG_FEATURE_TELNETD_INETD
- ts = next;
}
-#endif /* CONFIG_FEATURE_TELNETD_INETD */
-
- } while (1);
+ skip4:
+ ts = next;
+ continue;
+ kill_session:
+ free_session(ts);
+ ts = next;
+ }
- return 0;
+ goto again;
}
projects / oweals / busybox.git / blobdiff