diff options
Diffstat (limited to 'release/src/router/busybox/networking/telnetd.c')
| -rw-r--r-- | release/src/router/busybox/networking/telnetd.c | 1048 |
1 files changed, 550 insertions, 498 deletions
diff --git a/release/src/router/busybox/networking/telnetd.c b/release/src/router/busybox/networking/telnetd.c index e41cfe58..4c5ea3ab 100644 --- a/release/src/router/busybox/networking/telnetd.c +++ b/release/src/router/busybox/networking/telnetd.c @@ -1,10 +1,9 @@ -/* $Id: telnetd.c,v 1.1.3.1 2004/12/29 07:07:46 honor 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 @@ -22,607 +21,660 @@ * 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 -"/bin/sh"; -#endif -static const char *issuefile = "/etc/issue.net"; - -/* shell name and arguments */ - -static const char *argv_init[] = {NULL, NULL}; - -/* structure that describes a session */ +/* 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, sockfd_write, ptyfd; + /* two circular buffers */ - char *buf1, *buf2; + /*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) 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 }; -*/ +/* Globals */ static int maxfd; - static struct tsession *sessions; +static const char *loginpath = "/bin/login"; +static const char *issuefile = "/etc/issue.net"; /* - - 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->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 */ + OPT_FOREGROUND = (1 << 6) * ENABLE_FEATURE_TELNETD_STANDALONE, /* -F */ +}; 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( + USE_FEATURE_TELNETD_STANDALONE(int master_fd, int sock) + SKIP_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 > maxfd) + maxfd = fd; + ts->ptyfd = fd; + ndelay_on(fd); +#if ENABLE_FEATURE_TELNETD_STANDALONE + ts->sockfd_read = sock; + /* SO_KEEPALIVE by popular demand */ + setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, &const_int_1, sizeof(const_int_1)); + ndelay_on(sock); + if (!sock) { /* 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 > maxfd) + 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, 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); + fflush(NULL); /* flush all streams */ + 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; + } - /* NOT REACHED */ - syslog_msg(LOG_USER, LOG_ERR, "execv error"); - exit(1); + /* Child */ + /* Careful - we are after vfork! */ + + /* Restore default signal handling ASAP */ + bb_signals((1 << SIGCHLD) + (1 << SIGPIPE), SIG_DFL); + +#if ENABLE_FEATURE_TELNETD_STANDALONE + if (!(option_mask32 & OPT_INETD)) { + struct tsession *tp = sessions; + while (tp) { + close(tp->ptyfd); + close(tp->sockfd_read); + /* sockfd_write == sockfd_read for standalone telnetd */ + /*close(tp->sockfd_write);*/ + tp = tp->next; + } } +#endif + + /* Make new session and process group */ + setsid(); - ts->shell_pid = pid; + close(fd); +#if ENABLE_FEATURE_TELNETD_STANDALONE + close(sock); + if (master_fd >= 0) + close(master_fd); +#endif - return ts; + /* 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(stdout), + * 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, tty_name); + + /* Exec shell / login / whatever */ + login_argv[0] = loginpath; + login_argv[1] = NULL; + /* exec busybox applet (if PREFER_APPLETS=y), if that fails, + * exec external program */ + BB_EXECVP(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", loginpath);*/ } -#ifndef CONFIG_FEATURE_TELNETD_INETD +#if ENABLE_FEATURE_TELNETD_STANDALONE + static void free_session(struct tsession *ts) { struct tsession *t = sessions; - /* Unlink this telnet session from the session list. */ - if(t == ts) + if (option_mask32 & OPT_INETD) + exit(EXIT_SUCCESS); + + /* Unlink this telnet session from the session list */ + if (t == ts) 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 */ + maxfd = 0; + ts = sessions; + while (ts) { + if (maxfd < ts->ptyfd) + maxfd = ts->ptyfd; + if (maxfd < ts->sockfd_read) + maxfd = ts->sockfd_read; +#if 0 + /* Again, sockfd_write == sockfd_read here */ + if (maxfd < ts->sockfd_write) + 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 = 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; /* be happy, gcc */ + unsigned portnbr = 23; + char *opt_bindaddr = NULL; + char *opt_portnbr; +#else + enum { + IS_INETD = 1, + master_fd = -1, + portnbr = 23, + }; +#endif + /* 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)); + 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_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(-1, 0); + if (!sessions) /* pty opening or vfork problem, exit */ + return 1; /* make_new_session prints error message */ + } else { + master_fd = create_and_bind_stream_or_die(opt_bindaddr, portnbr); + xlisten(master_fd, 1); + } +#else + sessions = make_new_session(); + if (!sessions) /* pty opening or vfork problem, exit */ + return 1; /* make_new_session prints error message */ +#endif - if (daemon(0, 0) < 0) - bb_perror_msg_and_die("daemon"); - - - maxfd = master_fd; -#endif /* CONFIG_FEATURE_TELNETD_INETD */ + /* We don't want to die if just one session is broken */ + signal(SIGPIPE, SIG_IGN); - do { - struct tsession *ts; + if (opt & OPT_WATCHCHILD) + signal(SIGCHLD, handle_sigchld); + else /* prevent dead children from becoming zombies */ + signal(SIGCHLD, SIG_IGN); - FD_ZERO(&rdfdset); - FD_ZERO(&wrfdset); +/* + 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-- +----------+ - /* 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 = 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 > maxfd) + 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; + count = select(maxfd + 1, &rdfdset, &wrfdset, NULL, NULL); + if (count < 0) + goto again; /* EINTR or ENOMEM */ + +#if ENABLE_FEATURE_TELNETD_STANDALONE + /* First 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(master_fd, fd); + if (new_ts) { + new_ts->next = sessions; + sessions = new_ts; + } else { + close(fd); } -#endif /* CONFIG_FEATURE_TELNETD_INETD */ - - selret = select(maxfd + 1, &rdfdset, &wrfdset, 0, 0); - - if (!selret) - break; + } +#endif -#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); - } + /* Then check for data tunneling. */ + ts = 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; } + ts->size1 -= count; + ts->wridx1 += count; + if (ts->wridx1 >= BUFSIZE) /* actually == BUFSIZE */ + ts->wridx1 = 0; } - - /* 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; - } - -#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; + 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->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->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->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->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; } |