OpenSolaris Launch

1 files changed, 371 insertions, 0 deletions

diff --git a/usr/src/cmd/cmd-inet/sbin/dhcpagent/script_handler.c b/usr/src/cmd/cmd-inet/sbin/dhcpagent/script_handler.c
new file mode 100644
index 0000000000..9dd9690748
--- /dev/null
+++ b/usr/src/cmd/cmd-inet/sbin/dhcpagent/script_handler.c
@@ -0,0 +1,371 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License, Version 1.0 only
+ * (the "License").  You may not use this file except in compliance
+ * with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+/*
+ * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
+ * Use is subject to license terms.
+ */
+
+#pragma ident	"%Z%%M%	%I%	%E% SMI"
+
+#include <time.h>
+#include <stdio.h>
+#include <assert.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/wait.h>
+#include <signal.h>
+#include <fcntl.h>
+#include <dhcpmsg.h>
+#include "script_handler.h"
+
+/*
+ * scripts are directly managed by a script helper process. dhcpagent creates
+ * the helper process and it, in turn, creates a process to run the script
+ * dhcpagent owns one end of a pipe and the helper process owns the other end
+ * the helper process calls waitpid to wait for the script to exit. an alarm
+ * is set for SCRIPT_TIMEOUT seconds. If the alarm fires, SIGTERM is sent to
+ * the script process and a second alarm is set for SCRIPT_TIMEOUT_GRACE. if
+ * the second alarm fires, SIGKILL is sent to forcefully kill the script. when
+ * script exits, the helper process notifies dhcpagent by closing its end
+ * of the pipe.
+ */
+
+unsigned int	script_count;
+
+/*
+ * the signal to send to the script process. it is a global variable
+ * to this file as sigterm_handler needs it.
+ */
+
+static int	script_signal = SIGTERM;
+
+/*
+ * script's absolute timeout value. the first timeout is set to SCRIPT_TIMEOUT
+ * seconds from the time it is started. SIGTERM is sent on the first timeout
+ * the second timeout is set to SCRIPT_TIMEOUT_GRACE from the first timeout
+ * and SIGKILL is sent on the second timeout.
+ */
+static time_t		timeout;
+
+/*
+ * sigalarm_handler(): signal handler for SIGARLM
+ *
+ *   input: int: signal the handler was called with
+ *  output: void
+ */
+
+/* ARGSUSED */
+static void
+sigalarm_handler(int sig)
+{
+	time_t	now;
+
+	/* set a another alarm if it fires too early */
+	now = time(NULL);
+	if (now < timeout)
+		(void) alarm(timeout - now);
+}
+
+/*
+ * sigterm_handler(): signal handler for SIGTERM, fired when dhcpagent wants
+ *		      to stop the script
+ *   input: int: signal the handler was called with
+ *  output: void
+ */
+
+/* ARGSUSED */
+static void
+sigterm_handler(int sig)
+{
+	if (script_signal != SIGKILL) {
+		/* send SIGKILL SCRIPT_TIMEOUT_GRACE seconds from now */
+		script_signal = SIGKILL;
+		timeout = time(NULL) + SCRIPT_TIMEOUT_GRACE;
+		(void) alarm(SCRIPT_TIMEOUT_GRACE);
+	}
+}
+
+/*
+ * run_script(): it forks a process to execute the script
+ *
+ *   input: struct ifslist *: the interface
+ *	    const char *: the event name
+ *	    int: the pipe end owned by the script helper process
+ *  output: void
+ */
+static void
+run_script(struct ifslist *ifsp, const char *event, int fd)
+{
+	int		n;
+	char		c;
+	char		*name;
+	pid_t		pid;
+	time_t		now;
+	extern int	errno;
+
+	if ((pid = fork()) == -1) {
+		return;
+	}
+	if (pid == 0) {
+		name = strrchr(SCRIPT_PATH, '/') + 1;
+
+		/* close all files */
+		closefrom(0);
+
+		/* redirect stdin, stdout and stderr to /dev/null */
+		if ((n = open("/dev/null", O_RDWR)) < 0)
+			exit(-1);
+
+		(void) dup2(n, STDOUT_FILENO);
+		(void) dup2(n, STDERR_FILENO);
+
+		(void) execl(SCRIPT_PATH, name, ifsp->if_name, event, NULL);
+		_exit(127);
+	}
+
+	/*
+	 * the first timeout fires SCRIPT_TIMEOUT seconds from now.
+	 */
+	timeout = time(NULL) + SCRIPT_TIMEOUT;
+	(void) sigset(SIGALRM, sigalarm_handler);
+	(void) alarm(SCRIPT_TIMEOUT);
+
+	/*
+	 * pass script's pid to dhcpagent.
+	 */
+	(void) write(fd, &pid, sizeof (pid));
+
+	for (;;) {
+		if (waitpid(pid, NULL, 0) >= 0) {
+			/* script has exited */
+			c = SCRIPT_OK;
+			break;
+		}
+
+		if (errno != EINTR) {
+			return;
+		}
+
+		now = time(NULL);
+		if (now >= timeout) {
+			(void) kill(pid, script_signal);
+			if (script_signal == SIGKILL) {
+				c = SCRIPT_KILLED;
+				break;
+			}
+
+			script_signal = SIGKILL;
+			timeout = now + SCRIPT_TIMEOUT_GRACE;
+			(void) alarm(SCRIPT_TIMEOUT_GRACE);
+		}
+	}
+
+	(void) write(fd, &c, 1);
+}
+
+/*
+ * script_cleanup(): cleanup helper function
+ *
+ *   input: struct ifslist *: the interface
+ *  output: void
+ */
+
+static void
+script_cleanup(struct ifslist *ifsp)
+{
+	ifsp->if_script_helper_pid = -1;
+	ifsp->if_script_pid = -1;
+
+	if (ifsp->if_script_fd != -1) {
+		assert(ifsp->if_script_event_id != -1);
+		assert(ifsp->if_script_callback != NULL);
+
+		(void) iu_unregister_event(eh, ifsp->if_script_event_id, NULL);
+		(void) close(ifsp->if_script_fd);
+		ifsp->if_script_event_id = -1;
+		ifsp->if_script_fd = -1;
+		ifsp->if_script_callback(ifsp, ifsp->if_callback_msg);
+		ifsp->if_script_callback = NULL;
+		ifsp->if_script_event = NULL;
+		ifsp->if_callback_msg = NULL;
+
+		(void) release_ifs(ifsp);
+		script_count--;
+	}
+}
+
+/*
+ * script_exit(): does cleanup and invokes callback when script exits
+ *
+ *   input: eh_t *: unused
+ *	    int: the end of pipe owned by dhcpagent
+ *	    short: unused
+ *	    eh_event_id_t: unused
+ *	    void *: the interface
+ *  output: void
+ */
+
+/* ARGSUSED */
+static void
+script_exit(iu_eh_t *ehp, int fd, short events, iu_event_id_t id, void *arg)
+{
+	char		c;
+
+	if (read(fd, &c, 1) <= 0) {
+		c = SCRIPT_FAILED;
+	}
+
+	if (c == SCRIPT_OK) {
+		dhcpmsg(MSG_DEBUG, "script ok");
+	} else if (c == SCRIPT_KILLED) {
+		dhcpmsg(MSG_DEBUG, "script killed");
+	} else {
+		dhcpmsg(MSG_DEBUG, "script failed");
+	}
+
+	script_cleanup(arg);
+}
+
+/*
+ * script_start(): tries to run the script
+ *
+ *   input: struct ifslist *: the interface
+ *	    const char *: the event name
+ *	    script_callback_t: callback function
+ *	    void *: data to the callback function
+ *  output: int: 1 if script starts successfully
+ *	    int *: the returned value of the callback function if script
+ *		starts unsuccessfully
+ */
+int
+script_start(struct ifslist *ifsp, const char *event,
+		script_callback_t *callback, const char *msg, int *status)
+{
+	int		n;
+	int		fds[2];
+	pid_t		pid;
+	iu_event_id_t	event_id;
+
+	assert(callback != NULL);
+
+	if (access(SCRIPT_PATH, X_OK) == -1) {
+		/* script does not exist */
+		goto out;
+	}
+	if (ifsp->if_script_pid != -1) {
+		/* script is running, stop it */
+		dhcpmsg(MSG_ERROR, "script_start: stop script");
+		script_stop(ifsp);
+	}
+
+	/*
+	 * dhcpagent owns one end of the pipe and script helper process
+	 * owns the other end. dhcpagent reads on the pipe; and the helper
+	 * process notifies it when the script exits.
+	 */
+	if (pipe(fds) < 0) {
+		dhcpmsg(MSG_ERROR, "script_start: can't create pipe");
+		goto out;
+	}
+
+	if ((pid = fork()) < 0) {
+		dhcpmsg(MSG_ERROR, "script_start: can't fork");
+		(void) close(fds[0]);
+		(void) close(fds[1]);
+		goto out;
+	}
+
+	if (pid == 0) {
+		/*
+		 * SIGCHLD is ignored in dhcpagent, the helper process
+		 * needs it. it calls waitpid to wait for the script to exit.
+		 */
+		(void) close(fds[0]);
+		(void) sigset(SIGCHLD, SIG_DFL);
+		(void) sigset(SIGTERM, sigterm_handler);
+		run_script(ifsp, event, fds[1]);
+		exit(0);
+	}
+
+	(void) close(fds[1]);
+
+	/* get the script's pid */
+	if (read(fds[0], &ifsp->if_script_pid, sizeof (pid_t)) !=
+	    sizeof (pid_t)) {
+		(void) kill(pid, SIGKILL);
+		ifsp->if_script_pid = -1;
+		(void) close(fds[0]);
+		goto out;
+	}
+
+	ifsp->if_script_helper_pid = pid;
+	event_id = iu_register_event(eh, fds[0], POLLIN, script_exit, ifsp);
+	if (event_id == -1) {
+		(void) close(fds[0]);
+		script_stop(ifsp);
+		goto out;
+	}
+
+	script_count++;
+	ifsp->if_script_event_id = event_id;
+	ifsp->if_script_callback = callback;
+	ifsp->if_script_event = event;
+	ifsp->if_callback_msg = msg;
+	ifsp->if_script_fd = fds[0];
+	hold_ifs(ifsp);
+	return (1);
+
+out:
+	/* callback won't be called in script_exit, so call it here */
+	n = callback(ifsp, msg);
+	if (status != NULL)
+		*status = n;
+
+	return (0);
+}
+
+/*
+ * script_stop(): stops the script if it is running
+ *
+ *   input: struct ifslist *: the interface
+ *  output: void
+ */
+void
+script_stop(struct ifslist *ifsp)
+{
+	if (ifsp->if_script_pid != -1) {
+		assert(ifsp->if_script_helper_pid != -1);
+
+		/*
+		 * sends SIGTERM to the script and asks the helper process
+		 * to send SIGKILL if it does not exit after
+		 * SCRIPT_TIMEOUT_GRACE seconds.
+		 */
+		(void) kill(ifsp->if_script_pid, SIGTERM);
+		(void) kill(ifsp->if_script_helper_pid, SIGTERM);
+	}
+
+	script_cleanup(ifsp);
+}