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
  17     along with this program; if not, write to the Free Software
  18     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  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.%s",
  45                         VTY_NEWLINE);
  46                 return CMD_WARNING;
  47         }
  48
  49         fflush(stdout);
  50         fflush(stderr);
  51
  52         /* need to temporarily block SIGCHLD because it could arrive between
  53          * fork() call and setting the integrated_write_pid variable.  This
  54          * would mean the completion call gets lost and this hangs forever.
  55          */
  56         sigemptyset(&oldmask);
  57         sigemptyset(&sigmask);
  58         sigaddset(&sigmask, SIGCHLD);
  59         sigprocmask(SIG_BLOCK, &sigmask, &oldmask);
  60
  61         child = fork();
  62         if (child == -1) {
  63                 vty_out(vty, "%% configuration write fork() failed: %s.%s",
  64                         safe_strerror(errno), VTY_NEWLINE);
  65                 sigprocmask(SIG_SETMASK, &oldmask, NULL);
  66                 return CMD_WARNING;
  67         }
  68         if (child != 0) {
  69                 /* note: the VTY won't write a command return value to vtysh;  the
  70                  * session temporarily enters an intentional "hang" state.  This is
  71                  * to make sure latency in vtysh doing the config write (several
  72                  * seconds is not rare to see) does not interfere with watchfrr's
  73                  * supervisor job.
  74                  *
  75                  * The fd is duplicated here so we don't need to hold a vty pointer
  76                  * (which could become invalid in the meantime).
  77                  */
  78                 integrated_write_pid = child;
  79                 integrated_result_fd = dup(vty->wfd);
  80                 sigprocmask(SIG_SETMASK, &oldmask, NULL);
  81                 return CMD_SUSPEND;
  82         }
  83
  84         /* redirect stdout/stderr to vty session.  Note vty->wfd is marked
  85          * CLOEXEC, but dup2 will clear that flag. */
  86         dup2(vty->wfd, 1);
  87         dup2(vty->wfd, 2);
  88
  89         /* don't allow the user to pass parameters, we're root here!
  90          * should probably harden vtysh at some point too... */
  91         execl(VTYSH_BIN_PATH, "vtysh", "-w", NULL);
  92
  93         /* unbuffered write; we just messed with stdout... */
  94         char msg[512];
  95         snprintf(msg, sizeof(msg), "error executing %s: %s\n",
  96                  VTYSH_BIN_PATH, safe_strerror(errno));
  97         write(1, msg, strlen(msg));
  98         exit(1);
  99 }
 100
 101 void integrated_write_sigchld(int status)
 102 {
 103         uint8_t reply[4] = { 0, 0, 0, CMD_WARNING };
 104
 105         if (WIFEXITED(status)) {
 106                 zlog_info("configuration write completed with exit code %d",
 107                           WEXITSTATUS(status));
 108                 reply[3] = WEXITSTATUS(status);
 109         } else if (WIFSIGNALED(status)) {
 110                 zlog_warn("configuration write terminated by signal %d",
 111                           WTERMSIG(status));
 112         } else {
 113                 zlog_warn("configuration write terminated");
 114         }
 115
 116         if (reply[3] != CMD_SUCCESS) {
 117                 /* failure might be silent in vtysh without this */
 118                 static const char msg[] = "% Configuration write failed.\n";
 119                 write(integrated_result_fd, msg, strlen(msg));
 120         }
 121
 122         /* don't care about failures here, if the connection is broken the
 123          * return value will just be lost. */
 124         write(integrated_result_fd, reply, sizeof(reply));
 125         close(integrated_result_fd);
 126
 127         integrated_write_pid = -1;
 128 }
 129
 130 void watchfrr_vty_init(void)
 131 {
 132         integrated_write_pid = -1;
 133         install_element(ENABLE_NODE, &config_write_integrated_cmd);
 134 }