watchfrr/watchfrr_vty.c

   1 /*
   2  * watchfrr CLI functions.
   3  *
   4  * Copyright (C) 2016  David Lamparter for NetDEF, Inc.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License along
  17  * with this program; see the file COPYING; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  19  */
  20
  21 #include <zebra.h>
  22 #include <sys/wait.h>
  23
  24 #include "memory.h"
  25 #include "log.h"
  26 #include "vty.h"
  27 #include "command.h"
  28
  29 #include "watchfrr.h"
  30
  31 pid_t integrated_write_pid;
  32 static int integrated_result_fd;
  33
  34 DEFUN(config_write_integrated,
  35       config_write_integrated_cmd,
  36       "write integrated",
  37       "Write running configuration to memory, network, or terminal\n"
  38       "Write integrated all-daemon frr.conf file\n")
  39 {
  40         pid_t child;
  41         sigset_t oldmask, sigmask;
  42
  43         const char *e_inprog = "Configuration write already in progress.";
  44         const char *e_dmn = "Not all daemons are up, cannot write config.";
  45
  46         if (integrated_write_pid != -1) {
  47                 vty_out(vty, "%% %s\n", e_inprog);
  48                 return CMD_WARNING;
  49         }
  50
  51         /* check that all daemons are up before clobbering config */
  52         if (!check_all_up()) {
  53                 vty_out(vty, "%% %s\n", e_dmn);
  54                 /*
  55                  * vtysh interprets this return value to mean that it should
  56                  * not try to write the config itself
  57                  */
  58                 return CMD_WARNING_CONFIG_FAILED;
  59         }
  60
  61         fflush(stdout);
  62         fflush(stderr);
  63
  64         /* need to temporarily block SIGCHLD because it could arrive between
  65          * fork() call and setting the integrated_write_pid variable.  This
  66          * would mean the completion call gets lost and this hangs forever.
  67          */
  68         sigemptyset(&oldmask);
  69         sigemptyset(&sigmask);
  70         sigaddset(&sigmask, SIGCHLD);
  71         sigprocmask(SIG_BLOCK, &sigmask, &oldmask);
  72
  73         child = fork();
  74         if (child == -1) {
  75                 vty_out(vty, "%% configuration write fork() failed: %s.\n",
  76                         safe_strerror(errno));
  77                 sigprocmask(SIG_SETMASK, &oldmask, NULL);
  78                 return CMD_WARNING;
  79         }
  80         if (child != 0) {
  81                 /* note: the VTY won't write a command return value to vtysh;
  82                  * the
  83                  * session temporarily enters an intentional "hang" state.  This
  84                  * is
  85                  * to make sure latency in vtysh doing the config write (several
  86                  * seconds is not rare to see) does not interfere with
  87                  * watchfrr's
  88                  * supervisor job.
  89                  *
  90                  * The fd is duplicated here so we don't need to hold a vty
  91                  * pointer
  92                  * (which could become invalid in the meantime).
  93                  */
  94                 integrated_write_pid = child;
  95                 integrated_result_fd = dup(vty->wfd);
  96                 sigprocmask(SIG_SETMASK, &oldmask, NULL);
  97                 return CMD_SUSPEND;
  98         }
  99
 100         /* redirect stdout/stderr to vty session.  Note vty->wfd is marked
 101          * CLOEXEC, but dup2 will clear that flag. */
 102         dup2(vty->wfd, 1);
 103         dup2(vty->wfd, 2);
 104
 105         /* don't allow the user to pass parameters, we're root here!
 106          * should probably harden vtysh at some point too... */
 107         execl(VTYSH_BIN_PATH, "vtysh", "-w", NULL);
 108
 109         /* unbuffered write; we just messed with stdout... */
 110         char msg[512];
 111         snprintf(msg, sizeof(msg), "error executing %s: %s\n", VTYSH_BIN_PATH,
 112                  safe_strerror(errno));
 113         write(1, msg, strlen(msg));
 114         exit(1);
 115 }
 116
 117 DEFUN_NOSH (show_debugging_watchfrr,
 118             show_debugging_watchfrr_cmd,
 119             "show debugging [watchfrr]",
 120             SHOW_STR
 121             DEBUG_STR
 122             WATCHFRR_STR)
 123 {
 124         return CMD_SUCCESS;
 125 }
 126
 127 void integrated_write_sigchld(int status)
 128 {
 129         uint8_t reply[4] = {0, 0, 0, CMD_WARNING};
 130
 131         if (WIFEXITED(status)) {
 132                 zlog_info("configuration write completed with exit code %d",
 133                           WEXITSTATUS(status));
 134                 reply[3] = WEXITSTATUS(status);
 135         } else if (WIFSIGNALED(status)) {
 136                 zlog_warn("configuration write terminated by signal %d",
 137                           WTERMSIG(status));
 138         } else {
 139                 zlog_warn("configuration write terminated");
 140         }
 141
 142         if (reply[3] != CMD_SUCCESS) {
 143                 /* failure might be silent in vtysh without this */
 144                 static const char msg[] = "% Configuration write failed.\n";
 145                 write(integrated_result_fd, msg, strlen(msg));
 146         }
 147
 148         /* don't care about failures here, if the connection is broken the
 149          * return value will just be lost. */
 150         write(integrated_result_fd, reply, sizeof(reply));
 151         close(integrated_result_fd);
 152
 153         integrated_write_pid = -1;
 154 }
 155
 156 void watchfrr_vty_init(void)
 157 {
 158         integrated_write_pid = -1;
 159         install_element(ENABLE_NODE, &config_write_integrated_cmd);
 160         install_element(ENABLE_NODE, &show_debugging_watchfrr_cmd);
 161         install_element(CONFIG_NODE, &show_debugging_watchfrr_cmd);
 162 }