Add vty option to print output of shell cmd on every poll step

Change-Id: I005773b75f81fa5f6c90f53af508fc6debea208b

doc/examples/osmo-sysmon.cfg

@@ -14,3 +14,4 @@ netdev tun0
 ping example.com
 openvpn 127.0.0.1 1234
 file os-image /etc/image-datetime
+shellcmd kernel uname -a

src/Makefile.am

@@ -42,6 +42,7 @@ osmo_sysmon_SOURCES = \
 	osysmon_file.c \
 	osysmon_ping.c \
 	osysmon_openvpn.c \
+	osysmon_shellcmd.c \
 	osysmon_main.c \
 	$(NULL)
 

src/osysmon.h

@@ -13,6 +13,8 @@ struct ping_state;
 
 struct osysmon_state {
 	struct rtnl_client_state *rcs;
+	/* list of 'struct osysmon_cmd' */
+	struct llist_head shellcmds;
 	/* list of 'struct ctrl client' */
 	struct llist_head ctrl_clients;
 	/* list of 'struct openvpn_client' */
@@ -21,6 +23,7 @@ struct osysmon_state {
 	struct llist_head netdevs;
 	/* list of 'struct osysmon_file' */
 	struct llist_head files;
+	/* list of ping contexts */
 	struct ping_state *pings;
 };
 
@@ -36,7 +39,6 @@ enum osysmon_vty_node {
 	PING_NODE,
 };
 
-
 int osysmon_ctrl_go_parent(struct vty *vty);
 int osysmon_ctrl_init();
 int osysmon_ctrl_poll(struct value_node *parent);
@@ -56,3 +58,6 @@ int osysmon_openvpn_poll(struct value_node *parent);
 
 int osysmon_file_init();
 int osysmon_file_poll(struct value_node *parent);
+
+int osysmon_shellcmd_init();
+int osysmon_shellcmd_poll(struct value_node *parent);

src/osysmon_main.c

@@ -207,6 +207,7 @@ static void print_nodes(__attribute__((unused)) void *data)
 		osysmon_ping_poll(root);
 
 	osysmon_file_poll(root);
+	osysmon_shellcmd_poll(root);
 
 	display_update(root);
 	value_node_del(root);
@@ -221,6 +222,7 @@ int main(int argc, char **argv)
 	osmo_init_logging2(NULL, &log_info);
 
 	g_oss = talloc_zero(NULL, struct osysmon_state);
+	INIT_LLIST_HEAD(&g_oss->shellcmds);
 	INIT_LLIST_HEAD(&g_oss->ctrl_clients);
 	INIT_LLIST_HEAD(&g_oss->openvpn_clients);
 	INIT_LLIST_HEAD(&g_oss->netdevs);
@@ -229,6 +231,7 @@ int main(int argc, char **argv)
 	vty_init(&vty_info);
 	handle_options(argc, argv);
 	osysmon_sysinfo_init();
+	osysmon_shellcmd_init();
 	osysmon_ctrl_init();
 	osysmon_openvpn_init();
 	osysmon_rtnl_init();

src/osysmon_shellcmd.c

@@ -0,0 +1,174 @@
+/* Simple Osmocom System Monitor (osysmon): Support for monitoring through shell commands */
+
+/* (C) 2019 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
+ * All Rights Reserved.
+ * Author: Pau Espin Pedrol <pespin@sysmocom.de>
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ *  MA  02110-1301, USA.
+ */
+
+#include <string.h>
+#include <stdio.h>
+#include <errno.h>
+#include <sys/sysinfo.h>
+
+#include <osmocom/vty/vty.h>
+#include <osmocom/vty/command.h>
+
+#include "osysmon.h"
+#include "value_node.h"
+
+/***********************************************************************
+ * Data model
+ ***********************************************************************/
+
+struct osysmon_shellcmd {
+	struct llist_head list;
+	struct {
+		const char *name;
+		const char *cmd;
+	} cfg;
+};
+
+static struct osysmon_shellcmd *osysmon_shellcmd_find(const char *name)
+{
+	struct osysmon_shellcmd *oc;
+
+	llist_for_each_entry(oc, &g_oss->shellcmds, list) {
+		if (!strcmp(oc->cfg.name, name))
+			return oc;
+	}
+	return NULL;
+}
+
+static struct osysmon_shellcmd *osysmon_shellcmd_add(const char *name, const char *cmd)
+{
+	struct osysmon_shellcmd *oc;
+
+	if (osysmon_shellcmd_find(name))
+		return NULL;
+
+	oc = talloc_zero(g_oss, struct osysmon_shellcmd);
+	OSMO_ASSERT(oc);
+	oc->cfg.name = talloc_strdup(oc, name);
+	oc->cfg.cmd = talloc_strdup(oc, cmd);
+	llist_add_tail(&oc->list, &g_oss->shellcmds);
+	return oc;
+}
+
+static void osysmon_shellcmd_destroy(struct osysmon_shellcmd *oc)
+{
+	llist_del(&oc->list);
+	talloc_free(oc);
+}
+
+static void osysmon_shellcmd_run(struct osysmon_shellcmd *oc, struct value_node *parent)
+{
+	char buf[512];
+	FILE *f;
+	char *p = buf;
+	long offset = 0;
+
+	f = popen(oc->cfg.cmd, "r");
+	if (!f) {
+		snprintf(buf, sizeof(buf), "<popen failed (%d)>", errno);
+		value_node_add(parent, oc->cfg.name, buf);
+		return;
+	}
+
+	while ((offset = fread(p, 1, sizeof(buf) - 1 - (p - buf), f)) != 0) {
+		p += offset;
+		*p = '\0';
+	}
+
+	pclose(f);
+
+	if (buf != p) {
+		if (*(p - 1) == '\n') /* Remove final new line if exists */
+			*(p - 1) = '\0';
+		value_node_add(parent, oc->cfg.name, buf);
+	} else {
+		value_node_add(parent, oc->cfg.name, "<EMPTY>");
+	}
+}
+
+/***********************************************************************
+ * VTY
+ ***********************************************************************/
+
+#define CMD_STR "Configure a shell command to be executed\n"
+DEFUN(cfg_shellcmd, cfg_shellcmd_cmd,
+	"shellcmd NAME .TEXT",
+	CMD_STR "Name of this shell command snippet\n" "Command to run\n")
+{
+	struct osysmon_shellcmd *oc;
+	char *concat = argv_concat(argv, argc, 1);
+	oc = osysmon_shellcmd_add(argv[0], concat);
+	talloc_free(concat);
+	if (!oc) {
+		vty_out(vty, "Couldn't add shell cmd, maybe it exists?%s", VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_no_shellcmd, cfg_no_shellcmd_cmd,
+	"no shellcmd NAME",
+	NO_STR CMD_STR "Name of this shell command snippet\n")
+{
+	struct osysmon_shellcmd *oc;
+	oc = osysmon_shellcmd_find(argv[0]);
+	if (!oc) {
+		vty_out(vty, "Cannot find shell cmd for '%s'%s", argv[0], VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+	osysmon_shellcmd_destroy(oc);
+	return CMD_SUCCESS;
+}
+
+
+static void osysmon_shellcmd_vty_init(void)
+{
+	install_element(CONFIG_NODE, &cfg_shellcmd_cmd);
+	install_element(CONFIG_NODE, &cfg_no_shellcmd_cmd);
+}
+
+/***********************************************************************
+ * Runtime Code
+ ***********************************************************************/
+
+/* called once on startup before config file parsing */
+int osysmon_shellcmd_init()
+{
+	osysmon_shellcmd_vty_init();
+	return 0;
+}
+
+/* called periodically */
+int osysmon_shellcmd_poll(struct value_node *parent)
+{
+	struct value_node *vn_file;
+	struct osysmon_shellcmd *oc;
+
+	vn_file = value_node_add(parent, "shellcmd", NULL);
+
+	llist_for_each_entry(oc, &g_oss->shellcmds, list)
+		osysmon_shellcmd_run(oc, vn_file);
+
+	return 0;
+}