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         if (integrated_write_pid != -1) {
  44                 vty_out(vty, "%% configuration write already in progress.\n");
  45                 return CMD_WARNING;
  46         }
  47
  48         fflush(stdout);
  49         fflush(stderr);
  50
  51         /* need to temporarily block SIGCHLD because it could arrive between
  52          * fork() call and setting the integrated_write_pid variable.  This
  53          * would mean the completion call gets lost and this hangs forever.
  54          */
  55         sigemptyset(&oldmask);
  56         sigemptyset(&sigmask);
  57         sigaddset(&sigmask, SIGCHLD);
  58         sigprocmask(SIG_BLOCK, &sigmask, &oldmask);
  59
  60         child = fork();
  61         if (child == -1) {
  62                 vty_out(vty, "%% configuration write fork() failed: %s.\n",
  63                         safe_strerror(errno));
  64                 sigprocmask(SIG_SETMASK, &oldmask, NULL);
  65                 return CMD_WARNING;
  66         }
  67         if (child != 0) {
  68                 /* note: the VTY won't write a command return value to vtysh;
  69                  * the
  70                  * session temporarily enters an intentional "hang" state.  This
  71                  * is
  72                  * to make sure latency in vtysh doing the config write (several
  73                  * seconds is not rare to see) does not interfere with
  74                  * watchfrr's
  75                  * supervisor job.
  76                  *
  77                  * The fd is duplicated here so we don't need to hold a vty
  78                  * pointer
  79                  * (which could become invalid in the meantime).
  80                  */
  81                 integrated_write_pid = child;
  82                 integrated_result_fd = dup(vty->wfd);
  83                 sigprocmask(SIG_SETMASK, &oldmask, NULL);
  84                 return CMD_SUSPEND;
  85         }
  86
  87         /* redirect stdout/stderr to vty session.  Note vty->wfd is marked
  88          * CLOEXEC, but dup2 will clear that flag. */
  89         dup2(vty->wfd, 1);
  90         dup2(vty->wfd, 2);
  91
  92         /* don't allow the user to pass parameters, we're root here!
  93          * should probably harden vtysh at some point too... */
  94         execl(VTYSH_BIN_PATH, "vtysh", "-w", NULL);
  95
  96         /* unbuffered write; we just messed with stdout... */
  97         char msg[512];
  98         snprintf(msg, sizeof(msg), "error executing %s: %s\n", VTYSH_BIN_PATH,
  99                  safe_strerror(errno));
 100         write(1, msg, strlen(msg));
 101         exit(1);
 102 }
 103
 104 void integrated_write_sigchld(int status)
 105 {
 106         uint8_t reply[4] = {0, 0, 0, CMD_WARNING};
 107
 108         if (WIFEXITED(status)) {
 109                 zlog_info("configuration write completed with exit code %d",
 110                           WEXITSTATUS(status));
 111                 reply[3] = WEXITSTATUS(status);
 112         } else if (WIFSIGNALED(status)) {
 113                 zlog_warn("configuration write terminated by signal %d",
 114                           WTERMSIG(status));
 115         } else {
 116                 zlog_warn("configuration write terminated");
 117         }
 118
 119         if (reply[3] != CMD_SUCCESS) {
 120                 /* failure might be silent in vtysh without this */
 121                 static const char msg[] = "% Configuration write failed.\n";
 122                 write(integrated_result_fd, msg, strlen(msg));
 123         }
 124
 125         /* don't care about failures here, if the connection is broken the
 126          * return value will just be lost. */
 127         write(integrated_result_fd, reply, sizeof(reply));
 128         close(integrated_result_fd);
 129
 130         integrated_write_pid = -1;
 131 }
 132
 133 void watchfrr_vty_init(void)
 134 {
 135         integrated_write_pid = -1;
 136         install_element(ENABLE_NODE, &config_write_integrated_cmd);
 137 }