xatonum.h: add comment
[oweals/busybox.git] / networking / telnetd.c
index 96620d949f8434c833c5055aa7f87317fd65dc57..cccf03dfd54944bd88ff059eab52392117511db5 100644 (file)
@@ -141,7 +141,7 @@ remove_iacs(struct tsession *ts, int *pnum_totty)
                }
        }
 
-       num_totty = totty - ptr0;   
+       num_totty = totty - ptr0;
        *pnum_totty = num_totty;
        /* the difference between ptr and totty is number of iacs
           we removed from the stream. Adjust buf1 accordingly. */
@@ -203,7 +203,7 @@ getpty(char *line, int size)
 
 static struct tsession *
 make_new_session(
-               USE_FEATURE_TELNETD_STANDALONE(int sock_r, int sock_w)
+               USE_FEATURE_TELNETD_STANDALONE(int sock)
                SKIP_FEATURE_TELNETD_STANDALONE(void)
 ) {
        const char *login_argv[2];
@@ -221,19 +221,23 @@ make_new_session(
                bb_error_msg("can't create pty");
                return NULL;
        }
-       if (fd > maxfd) maxfd = fd;
+       if (fd > maxfd)
+               maxfd = fd;
        ts->ptyfd = fd;
        ndelay_on(fd);
 #if ENABLE_FEATURE_TELNETD_STANDALONE
-       if (sock_w > maxfd) maxfd = sock_w;
-       ts->sockfd_write = sock_w;
-       ndelay_on(sock_w);
-       if (sock_r > maxfd) maxfd = sock_r;
-       ts->sockfd_read = sock_r;
-       ndelay_on(sock_r);
+       ts->sockfd_read = sock;
+       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);
+       }
+       ts->sockfd_write = sock;
+       if (sock > maxfd)
+               maxfd = sock;
 #else
-       ts->sockfd_write = 1;
        /* ts->sockfd_read = 0; - done by xzalloc */
+       ts->sockfd_write = 1;
        ndelay_on(0);
        ndelay_on(1);
 #endif
@@ -259,7 +263,7 @@ make_new_session(
        if (pid < 0) {
                free(ts);
                close(fd);
-               /* sock_r and sock_w will be closed by caller */
+               /* sock will be closed by caller */
                bb_perror_msg("vfork");
                return NULL;
        }
@@ -310,6 +314,14 @@ make_new_session(
        _exit(1); /*bb_perror_msg_and_die("execv %s", 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
@@ -317,6 +329,9 @@ free_session(struct tsession *ts)
 {
        struct tsession *t = sessions;
 
+       if (option_mask32 & OPT_INETD)
+               exit(0);
+
        /* Unlink this telnet session from the session list */
        if (t == ts)
                sessions = ts->next;
@@ -326,35 +341,41 @@ free_session(struct tsession *ts)
                t->next = ts->next;
        }
 
+#if 0
        /* It was said that "normal" telnetd just closes ptyfd,
         * doesn't send SIGKILL. When we close ptyfd,
         * kernel sends SIGHUP to processes having slave side opened. */
-       /*kill(ts->shell_pid, SIGKILL);
-       wait4(ts->shell_pid, NULL, 0, NULL);*/
+       kill(ts->shell_pid, SIGKILL);
+       wait4(ts->shell_pid, NULL, 0, NULL);
+#endif
        close(ts->ptyfd);
        close(ts->sockfd_read);
-       /* error if ts->sockfd_read == ts->sockfd_write. So what? ;) */
-       close(ts->sockfd_write);
+       /* We do not need to close(ts->sockfd_write), it's the same
+        * as sockfd_read unless we are in inetd mode. But in inetd mode
+        * we do not reach this */
        free(ts);
 
        /* Scan all sessions and find new maxfd */
-       ts = sessions;
        maxfd = 0;
+       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;
        }
 }
 
 #else /* !FEATURE_TELNETD_STANDALONE */
 
-/* Never actually called */
-void free_session(struct tsession *ts);
+/* Used in main() only, thus exits. */
+#define free_session(ts) return 0
 
 #endif
 
@@ -397,13 +418,6 @@ int telnetd_main(int argc, char **argv)
                portnbr = 23,
        };
 #endif
-       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 */
-       };
-
        /* 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"),
@@ -415,7 +429,7 @@ int telnetd_main(int argc, char **argv)
                /*bb_error_msg("listening for connections");*/
                if (!(opt & OPT_FOREGROUND)) {
                        /* DAEMON_CHDIR_ROOT was giving inconsistent
-                        * behavior with/wthout -F, -i */
+                        * behavior with/without -F, -i */
                        bb_daemonize_or_rexec(0 /*DAEMON_CHDIR_ROOT*/, argv);
                }
        }
@@ -434,7 +448,7 @@ int telnetd_main(int argc, char **argv)
 
 #if ENABLE_FEATURE_TELNETD_STANDALONE
        if (IS_INETD) {
-               sessions = make_new_session(0, 1);
+               sessions = make_new_session(0);
                if (!sessions) /* pty opening or vfork problem, exit */
                        return 1; /* make_new_session prints error message */
        } else {
@@ -483,6 +497,7 @@ int telnetd_main(int argc, char **argv)
        while (ts) {
                struct tsession *next = ts->next; /* in case we free ts. */
                if (ts->shell_pid == -1) {
+                       /* Child died ad we detected that */
                        free_session(ts);
                } else {
                        if (ts->size1 > 0)       /* can write to pty */
@@ -519,7 +534,7 @@ int telnetd_main(int argc, char **argv)
                if (fd < 0)
                        goto again;
                /* Create a new session and link it into our active list */
-               new_ts = make_new_session(fd, fd);
+               new_ts = make_new_session(fd);
                if (new_ts) {
                        new_ts->next = sessions;
                        sessions = new_ts;
@@ -543,11 +558,7 @@ int telnetd_main(int argc, char **argv)
                        if (count < 0) {
                                if (errno == EAGAIN)
                                        goto skip1;
-                               if (IS_INETD)
-                                       return 0;
-                               free_session(ts);
-                               ts = next;
-                               continue;
+                               goto kill_session;
                        }
                        ts->size1 -= count;
                        ts->wridx1 += count;
@@ -562,11 +573,7 @@ int telnetd_main(int argc, char **argv)
                        if (count < 0) {
                                if (errno == EAGAIN)
                                        goto skip2;
-                               if (IS_INETD)
-                                       return 0;
-                               free_session(ts);
-                               ts = next;
-                               continue;
+                               goto kill_session;
                        }
                        ts->size2 -= count;
                        ts->wridx2 += count;
@@ -577,7 +584,7 @@ int telnetd_main(int argc, char **argv)
                /* Should not be needed, but... remove_iacs is actually buggy
                 * (it cannot process iacs which wrap around buffer's end)!
                 * Since properly fixing it requires writing bigger code,
-                * we will rely instead on this code making it virtually impossible
+                * we rely instead on this code making it virtually impossible
                 * to have wrapped iac (people don't type at 2k/second).
                 * It also allows for bigger reads in common case. */
                if (ts->size1 == 0) {
@@ -596,16 +603,11 @@ int telnetd_main(int argc, char **argv)
                        if (count <= 0) {
                                if (count < 0 && errno == EAGAIN)
                                        goto skip3;
-                               if (IS_INETD)
-                                       return 0;
-                               free_session(ts);
-                               ts = next;
-                               continue;
+                               goto kill_session;
                        }
                        /* Ignore trailing NUL if it is there */
                        if (!TS_BUF1[ts->rdidx1 + count - 1]) {
-                               if (!--count)
-                                       goto skip3;
+                               --count;
                        }
                        ts->size1 += count;
                        ts->rdidx1 += count;
@@ -620,11 +622,7 @@ int telnetd_main(int argc, char **argv)
                        if (count <= 0) {
                                if (count < 0 && errno == EAGAIN)
                                        goto skip4;
-                               if (IS_INETD)
-                                       return 0;
-                               free_session(ts);
-                               ts = next;
-                               continue;
+                               goto kill_session;
                        }
                        ts->size2 += count;
                        ts->rdidx2 += count;
@@ -633,6 +631,11 @@ int telnetd_main(int argc, char **argv)
                }
  skip4:
                ts = next;
+               continue;
+ kill_session:
+               free_session(ts);
+               ts = next;
        }
+
        goto again;
 }