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https://github.com/sheumann/hush.git
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telnetd: more compact version of the fix for stray open fds
function old new delta telnetd_main 1520 1527 +7 make_new_session 510 416 -94 ------------------------------------------------------------------------------ (add/remove: 0/0 grow/shrink: 1/1 up/down: 7/-94) Total: -87 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko
parent
a4bcbd0e04
commit
1d77db8459
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@ -32,11 +32,12 @@
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#endif
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#include <arpa/telnet.h>
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/* Structure that describes a session */
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struct tsession {
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struct tsession *next;
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pid_t shell_pid;
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int sockfd_read, sockfd_write, ptyfd;
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int sockfd_read;
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int sockfd_write;
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int ptyfd;
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/* two circular buffers */
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/*char *buf1, *buf2;*/
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@ -125,9 +126,9 @@ remove_iacs(struct tsession *ts, int *pnum_totty)
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* TELOPT_NAWS support!
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*/
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if ((ptr+2) >= end) {
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/* only the beginning of the IAC is in the
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/* Only the beginning of the IAC is in the
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buffer we were asked to process, we can't
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process this char. */
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process this char */
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break;
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}
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/*
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@ -153,13 +154,13 @@ remove_iacs(struct tsession *ts, int *pnum_totty)
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num_totty = totty - ptr0;
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*pnum_totty = num_totty;
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/* the difference between ptr and totty is number of iacs
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we removed from the stream. Adjust buf1 accordingly. */
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/* The difference between ptr and totty is number of iacs
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we removed from the stream. Adjust buf1 accordingly */
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if ((ptr - totty) == 0) /* 99.999% of cases */
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return ptr0;
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ts->wridx1 += ptr - totty;
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ts->size1 -= ptr - totty;
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/* move chars meant for the terminal towards the end of the buffer */
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/* Move chars meant for the terminal towards the end of the buffer */
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return memmove(ptr - num_totty, ptr0, num_totty);
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}
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@ -216,7 +217,7 @@ enum {
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static struct tsession *
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make_new_session(
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IF_FEATURE_TELNETD_STANDALONE(int master_fd, int sock)
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IF_FEATURE_TELNETD_STANDALONE(int sock)
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IF_NOT_FEATURE_TELNETD_STANDALONE(void)
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) {
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const char *login_argv[2];
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@ -228,18 +229,20 @@ make_new_session(
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/*ts->buf1 = (char *)(ts + 1);*/
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/*ts->buf2 = ts->buf1 + BUFSIZE;*/
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/* Got a new connection, set up a tty. */
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/* Got a new connection, set up a tty */
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fd = xgetpty(tty_name);
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if (fd > G.maxfd)
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G.maxfd = fd;
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ts->ptyfd = fd;
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ndelay_on(fd);
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close_on_exec_on(fd);
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#if ENABLE_FEATURE_TELNETD_STANDALONE
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ts->sockfd_read = sock;
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/* SO_KEEPALIVE by popular demand */
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setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, &const_int_1, sizeof(const_int_1));
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ts->sockfd_read = sock;
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ndelay_on(sock);
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if (!sock) { /* We are called with fd 0 - we are in inetd mode */
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if (sock == 0) { /* We are called with fd 0 - we are in inetd mode */
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sock++; /* so use fd 1 for output */
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ndelay_on(sock);
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}
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@ -254,6 +257,7 @@ make_new_session(
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ndelay_on(0);
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ndelay_on(1);
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#endif
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/* Make the telnet client understand we will echo characters so it
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* should not do it locally. We don't tell the client to run linemode,
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* because we want to handle line editing and tab completion and other
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@ -303,42 +307,20 @@ make_new_session(
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/* Restore default signal handling ASAP */
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bb_signals((1 << SIGCHLD) + (1 << SIGPIPE), SIG_DFL);
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#if ENABLE_FEATURE_TELNETD_STANDALONE
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if (!(option_mask32 & OPT_INETD)) {
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struct tsession *tp = G.sessions;
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while (tp) {
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close(tp->ptyfd);
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close(tp->sockfd_read);
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/* sockfd_write == sockfd_read for standalone telnetd */
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/*close(tp->sockfd_write);*/
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tp = tp->next;
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}
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}
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#endif
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/* Make new session and process group */
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setsid();
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close(fd);
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#if ENABLE_FEATURE_TELNETD_STANDALONE
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if (master_fd >= 0)
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close(master_fd);
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close(sock);
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#endif
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/* Open the child's side of the tty. */
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/* Open the child's side of the tty */
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/* NB: setsid() disconnects from any previous ctty's. Therefore
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* we must open child's side of the tty AFTER setsid! */
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#if ENABLE_FEATURE_TELNETD_STANDALONE
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if (sock != 0) /* if we did not close 0 already */
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#endif
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close(0);
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close(0);
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xopen(tty_name, O_RDWR); /* becomes our ctty */
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xdup2(0, 1);
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xdup2(0, 2);
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tcsetpgrp(0, getpid()); /* switch this tty's process group to us */
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/* The pseudo-terminal allocated to the client is configured to operate in
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* cooked mode, and with XTABS CRMOD enabled (see tty(4)). */
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/* The pseudo-terminal allocated to the client is configured to operate
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* in cooked mode, and with XTABS CRMOD enabled (see tty(4)) */
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tcgetattr(0, &termbuf);
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termbuf.c_lflag |= ECHO; /* if we use readline we dont want this */
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termbuf.c_oflag |= ONLCR | XTABS;
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@ -359,7 +341,10 @@ make_new_session(
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login_argv[0] = G.loginpath;
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login_argv[1] = NULL;
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/* exec busybox applet (if PREFER_APPLETS=y), if that fails,
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* exec external program */
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* exec external program.
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* NB: sock is either 0 or has CLOEXEC set on it.
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* fd has CLOEXEC set on it too. These two fds will be closed here.
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*/
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BB_EXECVP(G.loginpath, (char **)login_argv);
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/* _exit is safer with vfork, and we shouldn't send message
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* to remote clients anyway */
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@ -496,12 +481,13 @@ int telnetd_main(int argc UNUSED_PARAM, char **argv)
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#if ENABLE_FEATURE_TELNETD_STANDALONE
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if (IS_INETD) {
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G.sessions = make_new_session(-1, 0);
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G.sessions = make_new_session(0);
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if (!G.sessions) /* pty opening or vfork problem, exit */
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return 1; /* make_new_session prints error message */
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} else {
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master_fd = create_and_bind_stream_or_die(opt_bindaddr, portnbr);
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xlisten(master_fd, 1);
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close_on_exec_on(master_fd);
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}
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#else
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G.sessions = make_new_session();
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@ -518,8 +504,8 @@ int telnetd_main(int argc UNUSED_PARAM, char **argv)
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signal(SIGCHLD, SIG_IGN);
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/*
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This is how the buffers are used. The arrows indicate the movement
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of data.
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This is how the buffers are used. The arrows indicate data flow.
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+-------+ wridx1++ +------+ rdidx1++ +----------+
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| | <-------------- | buf1 | <-------------- | |
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| | size1-- +------+ size1++ | |
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@ -545,7 +531,7 @@ int telnetd_main(int argc UNUSED_PARAM, char **argv)
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* before each select. Can be a problem with 500+ connections. */
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ts = G.sessions;
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while (ts) {
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struct tsession *next = ts->next; /* in case we free ts. */
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struct tsession *next = ts->next; /* in case we free ts */
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if (ts->shell_pid == -1) {
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/* Child died and we detected that */
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free_session(ts);
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@ -575,7 +561,7 @@ int telnetd_main(int argc UNUSED_PARAM, char **argv)
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goto again; /* EINTR or ENOMEM */
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#if ENABLE_FEATURE_TELNETD_STANDALONE
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/* First check for and accept new sessions. */
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/* Check for and accept new sessions */
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if (!IS_INETD && FD_ISSET(master_fd, &rdfdset)) {
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int fd;
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struct tsession *new_ts;
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@ -583,8 +569,10 @@ int telnetd_main(int argc UNUSED_PARAM, char **argv)
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fd = accept(master_fd, NULL, NULL);
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if (fd < 0)
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goto again;
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/* Create a new session and link it into our active list */
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new_ts = make_new_session(master_fd, fd);
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close_on_exec_on(fd);
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/* Create a new session and link it into active list */
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new_ts = make_new_session(fd);
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if (new_ts) {
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new_ts->next = G.sessions;
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G.sessions = new_ts;
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@ -594,15 +582,15 @@ int telnetd_main(int argc UNUSED_PARAM, char **argv)
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}
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#endif
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/* Then check for data tunneling. */
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/* Then check for data tunneling */
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ts = G.sessions;
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while (ts) { /* For all sessions... */
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struct tsession *next = ts->next; /* in case we free ts. */
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struct tsession *next = ts->next; /* in case we free ts */
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if (/*ts->size1 &&*/ FD_ISSET(ts->ptyfd, &wrfdset)) {
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int num_totty;
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unsigned char *ptr;
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/* Write to pty from buffer 1. */
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/* Write to pty from buffer 1 */
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ptr = remove_iacs(ts, &num_totty);
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count = safe_write(ts->ptyfd, ptr, num_totty);
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if (count < 0) {
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@ -617,7 +605,7 @@ int telnetd_main(int argc UNUSED_PARAM, char **argv)
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}
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skip1:
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if (/*ts->size2 &&*/ FD_ISSET(ts->sockfd_write, &wrfdset)) {
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/* Write to socket from buffer 2. */
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/* Write to socket from buffer 2 */
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count = MIN(BUFSIZE - ts->wridx2, ts->size2);
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count = iac_safe_write(ts->sockfd_write, (void*)(TS_BUF2(ts) + ts->wridx2), count);
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if (count < 0) {
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@ -647,7 +635,7 @@ int telnetd_main(int argc UNUSED_PARAM, char **argv)
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}
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if (/*ts->size1 < BUFSIZE &&*/ FD_ISSET(ts->sockfd_read, &rdfdset)) {
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/* Read from socket to buffer 1. */
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/* Read from socket to buffer 1 */
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count = MIN(BUFSIZE - ts->rdidx1, BUFSIZE - ts->size1);
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count = safe_read(ts->sockfd_read, TS_BUF1(ts) + ts->rdidx1, count);
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if (count <= 0) {
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@ -666,7 +654,7 @@ int telnetd_main(int argc UNUSED_PARAM, char **argv)
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}
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skip3:
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if (/*ts->size2 < BUFSIZE &&*/ FD_ISSET(ts->ptyfd, &rdfdset)) {
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/* Read from pty to buffer 2. */
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/* Read from pty to buffer 2 */
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count = MIN(BUFSIZE - ts->rdidx2, BUFSIZE - ts->size2);
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count = safe_read(ts->ptyfd, TS_BUF2(ts) + ts->rdidx2, count);
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if (count <= 0) {
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