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_NOSH(show_watchfrr_debugging,
  35            show_watchfrr_debugging_cmd,
  36            "show debugging [watchfrr]",
  37            SHOW_STR
  38            DEBUG_STR
  39            "WatchFRR\n")
  40 {
  41         return CMD_SUCCESS;
  42 }
  43
  44 DEFUN(config_write_integrated,
  45       config_write_integrated_cmd,
  46       "write integrated",
  47       "Write running configuration to memory, network, or terminal\n"
  48       "Write integrated all-daemon frr.conf file\n")
  49 {
  50         pid_t child;
  51         sigset_t oldmask, sigmask;
  52
  53         if (integrated_write_pid != -1) {
  54                 vty_out(vty, "%% configuration write already in progress.\n");
  55                 return CMD_WARNING;
  56         }
  57
  58         fflush(stdout);
  59         fflush(stderr);
  60
  61         /* need to temporarily block SIGCHLD because it could arrive between
  62          * fork() call and setting the integrated_write_pid variable.  This
  63          * would mean the completion call gets lost and this hangs forever.
  64          */
  65         sigemptyset(&oldmask);
  66         sigemptyset(&sigmask);
  67         sigaddset(&sigmask, SIGCHLD);
  68         sigprocmask(SIG_BLOCK, &sigmask, &oldmask);
  69
  70         child = fork();
  71         if (child == -1) {
  72                 vty_out(vty, "%% configuration write fork() failed: %s.\n",
  73                         safe_strerror(errno));
  74                 sigprocmask(SIG_SETMASK, &oldmask, NULL);
  75                 return CMD_WARNING;
  76         }
  77         if (child != 0) {
  78                 /* note: the VTY won't write a command return value to vtysh;
  79                  * the
  80                  * session temporarily enters an intentional "hang" state.  This
  81                  * is
  82                  * to make sure latency in vtysh doing the config write (several
  83                  * seconds is not rare to see) does not interfere with
  84                  * watchfrr's
  85                  * supervisor job.
  86                  *
  87                  * The fd is duplicated here so we don't need to hold a vty
  88                  * pointer
  89                  * (which could become invalid in the meantime).
  90                  */
  91                 integrated_write_pid = child;
  92                 integrated_result_fd = dup(vty->wfd);
  93                 sigprocmask(SIG_SETMASK, &oldmask, NULL);
  94                 return CMD_SUSPEND;
  95         }
  96
  97         /* redirect stdout/stderr to vty session.  Note vty->wfd is marked
  98          * CLOEXEC, but dup2 will clear that flag. */
  99         dup2(vty->wfd, 1);
 100         dup2(vty->wfd, 2);
 101
 102         /* don't allow the user to pass parameters, we're root here!
 103          * should probably harden vtysh at some point too... */
 104         execl(VTYSH_BIN_PATH, "vtysh", "-w", NULL);
 105
 106         /* unbuffered write; we just messed with stdout... */
 107         char msg[512];
 108         snprintf(msg, sizeof(msg), "error executing %s: %s\n", VTYSH_BIN_PATH,
 109                  safe_strerror(errno));
 110         write(1, msg, strlen(msg));
 111         exit(1);
 112 }
 113
 114 void integrated_write_sigchld(int status)
 115 {
 116         uint8_t reply[4] = {0, 0, 0, CMD_WARNING};
 117
 118         if (WIFEXITED(status)) {
 119                 zlog_info("configuration write completed with exit code %d",
 120                           WEXITSTATUS(status));
 121                 reply[3] = WEXITSTATUS(status);
 122         } else if (WIFSIGNALED(status)) {
 123                 zlog_warn("configuration write terminated by signal %d",
 124                           WTERMSIG(status));
 125         } else {
 126                 zlog_warn("configuration write terminated");
 127         }
 128
 129         if (reply[3] != CMD_SUCCESS) {
 130                 /* failure might be silent in vtysh without this */
 131                 static const char msg[] = "% Configuration write failed.\n";
 132                 write(integrated_result_fd, msg, strlen(msg));
 133         }
 134
 135         /* don't care about failures here, if the connection is broken the
 136          * return value will just be lost. */
 137         write(integrated_result_fd, reply, sizeof(reply));
 138         close(integrated_result_fd);
 139
 140         integrated_write_pid = -1;
 141 }
 142
 143 void watchfrr_vty_init(void)
 144 {
 145         integrated_write_pid = -1;
 146         install_element(ENABLE_NODE, &config_write_integrated_cmd);
 147         install_element(ENABLE_NODE, &show_watchfrr_debugging_cmd);
 148 }