[master]

[32692] Signal handlers added: sigint (ctrl-c) and sigterm (default kill)

RELNOTES

@@ -129,6 +129,9 @@ work on other platforms. Please report any problems and suggested fixes to
   for the bug report and a potential patch.
   [ISC-Bugs #34784]
 
+- Added support for gentle shutdown after signal is received.
+  [ISC-BUGS #32692]
+
 			Changes since 4.2.4
 
 - Correct code to calculate timing values in client to compare

client/dhclient.c

@@ -691,6 +691,10 @@ main(int argc, char **argv) {
 	dmalloc_outstanding = 0;
 #endif
 
+        /* install signal handlers */
+	signal(SIGINT, dhcp_signal_handler);   /* control-c */
+	signal(SIGTERM, dhcp_signal_handler);  /* kill */
+
 	/* If we're not supposed to wait before getting the address,
 	   don't. */
 	if (nowait)
@@ -704,7 +708,6 @@ main(int argc, char **argv) {
 	/* Start dispatching packets and timeouts... */
 	dispatch();
 
-	/*NOTREACHED*/
 	return 0;
 }
 
@@ -807,7 +810,6 @@ void run_stateless(int exit_mode)
 	/* Start dispatching packets and timeouts... */
 	dispatch();
 
-	/*NOTREACHED*/
 #endif /* DHCPv6 */
 	return;
 }

common/dispatch.c

@@ -3,7 +3,7 @@
    Network input dispatcher... */
 
 /*
- * Copyright (c) 2004-2011 by Internet Systems Consortium, Inc. ("ISC")
+ * Copyright (c) 2004-2011,2013 by Internet Systems Consortium, Inc. ("ISC")
  * Copyright (c) 1995-2003 by Internet Software Consortium
  *
  * Permission to use, copy, modify, and distribute this software for any
@@ -112,8 +112,15 @@ dispatch(void)
 
 	status = isc_app_ctxrun(dhcp_gbl_ctx.actx);
 
-	log_fatal ("Dispatch routine failed: %s -- exiting",
-		   isc_result_totext (status));
+        /*
+         * isc_app_ctxrun can be stopped by receiving a signal. It will
+         * return ISC_R_SUCCESS in that case. That is a normal behavior.
+         */
+
+	if (status != ISC_R_SUCCESS) {
+		log_fatal ("Dispatch routine failed: %s -- exiting",
+		           isc_result_totext (status));
+	}
 }
 
 void

includes/omapip/isclib.h

@@ -3,7 +3,7 @@
    connections to the isc and dns libraries */
 
 /*
- * Copyright (c) 2009 by Internet Systems Consortium, Inc. ("ISC")
+ * Copyright (c) 2009,2013 by Internet Systems Consortium, Inc. ("ISC")
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -119,4 +119,6 @@ isclib_make_dst_key(char          *inname,
 isc_result_t dhcp_context_create(void);
 void isclib_cleanup(void);
 
+void dhcp_signal_handler(int signal);
+
 #endif /* ISCLIB_H */

omapip/dispatch.c

@@ -3,7 +3,7 @@
    I/O dispatcher. */
 
 /*
- * Copyright (c) 2004,2007-2009 by Internet Systems Consortium, Inc. ("ISC")
+ * Copyright (c) 2004,2007-2009,2013 by Internet Systems Consortium, Inc. ("ISC")
  * Copyright (c) 1999-2003 by Internet Software Consortium
  *
  * Permission to use, copy, modify, and distribute this software for any
@@ -901,19 +901,65 @@ isc_result_t omapi_waiter_signal_handler (omapi_object_t *h,
 	return ISC_R_NOTFOUND;
 }
 
+/** @brief calls a given function on every object
+ *
+ * @param func function to be called
+ * @param p parameter to be passed to each function instance
+ *
+ * @return result (ISC_R_SUCCESS if successful, error code otherwise)
+ */
 isc_result_t omapi_io_state_foreach (isc_result_t (*func) (omapi_object_t *,
 							   void *),
 				     void *p)
 {
-	omapi_io_object_t *io;
+	omapi_io_object_t *io = NULL;
 	isc_result_t status;
+	omapi_io_object_t *next = NULL;
 
-	for (io = omapi_io_states.next; io; io = io -> next) {
-		if (io -> inner) {
-			status = (*func) (io -> inner, p);
-			if (status != ISC_R_SUCCESS)
-				return status;
-		}
+	/*
+	 * This just calls func on every inner object on the list. It would
+	 * be much simpler in general case, but one of the operations could be
+	 * release of the objects. Therefore we need to ref count the io and
+	 * io->next pointers.
+	 */
+
+	if (omapi_io_states.next) {
+		omapi_object_reference((omapi_object_t**)&io,
+				       (omapi_object_t*)omapi_io_states.next,
+				       MDL);
 	}
+
+	while(io) {
+	    /* If there's a next object, save it */
+	    if (io->next) {
+		omapi_object_reference((omapi_object_t**)&next,
+				       (omapi_object_t*)io->next, MDL);
+	    }
+	    if (io->inner) {
+		status = (*func) (io->inner, p);
+		if (status != ISC_R_SUCCESS) {
+		    /* Something went wrong. Let's stop using io & next pointer
+		     * and bail out */
+		    omapi_object_dereference((omapi_object_t**)&io, MDL);
+		    if (next) {
+			omapi_object_dereference((omapi_object_t**)&next, MDL);
+		    }
+		    return status;
+		}
+	    }
+	    /* Update the io pointer and free the next pointer */
+	    omapi_object_dereference((omapi_object_t**)&io, MDL);
+	    if (next) {
+		omapi_object_reference((omapi_object_t**)&io,
+				       (omapi_object_t*)next,
+				       MDL);
+		omapi_object_dereference((omapi_object_t**)&next, MDL);
+	    }
+	}
+
+	/*
+	 * The only way to get here is when next is NULL. There's no need
+	 * to dereference it.
+	 */
 	return ISC_R_SUCCESS;
 }

omapip/isclib.c

@@ -1,5 +1,5 @@
 /*
- * Copyright(c) 2009-2010 by Internet Systems Consortium, Inc.("ISC")
+ * Copyright(c) 2009-2010,2013 by Internet Systems Consortium, Inc.("ISC")
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -28,6 +28,7 @@
 #include "dhcpd.h"
 
 #include <sys/time.h>
+#include <signal.h>
 
 dhcp_context_t dhcp_gbl_ctx;
 
@@ -217,3 +218,20 @@ isclib_make_dst_key(char          *inname,
 				  &b, dhcp_gbl_ctx.mctx, dstkey));
 }
 
+/**
+ * signal handler that initiates server shutdown
+ *
+ * @param signal signal code that we received
+ */
+void dhcp_signal_handler(int signal) {
+	isc_appctx_t *ctx = dhcp_gbl_ctx.actx;
+	if (ctx && ctx->methods && ctx->methods->ctxshutdown) {
+		/*
+		 * Let's not use standard log facilities here. They may not be
+		 * signal safe, e.g. we could get the signal in the middle of
+		 * another log call
+		 */
+		printf("Received signal %d, initiating shutdown.\n", signal);
+		ctx->methods->ctxshutdown(ctx);
+	}
+}

relay/dhcrelay.c

@@ -34,6 +34,7 @@
 
 #include "dhcpd.h"
 #include <syslog.h>
+#include <signal.h>
 #include <sys/time.h>
 
 TIME default_lease_time = 43200; /* 12 hours... */
@@ -577,10 +578,13 @@ main(int argc, char **argv) {
 		dhcpv6_packet_handler = do_packet6;
 #endif
 
+        /* install signal handlers */
+	signal(SIGINT, dhcp_signal_handler);   /* control-c */
+	signal(SIGTERM, dhcp_signal_handler);  /* kill */
+
 	/* Start dispatching packets and timeouts... */
 	dispatch();
 
-	/* Not reached */
 	return (0);
 }
 

server/dhcpd.c

@@ -42,11 +42,11 @@ static const char url [] =
 #include "dhcpd.h"
 #include <omapip/omapip_p.h>
 #include <syslog.h>
+#include <signal.h>
 #include <errno.h>
 #include <limits.h>
 #include <sys/types.h>
 #include <sys/time.h>
-#include <signal.h>
 
 #if defined (PARANOIA)
 #  include <sys/types.h>
@@ -780,10 +780,20 @@ main(int argc, char **argv) {
 	omapi_set_int_value ((omapi_object_t *)dhcp_control_object,
 			     (omapi_object_t *)0, "state", server_running);
 
-	/* Receive packets and dispatch them... */
+        /* install signal handlers */
+	signal(SIGINT, dhcp_signal_handler);   /* control-c */
+	signal(SIGTERM, dhcp_signal_handler);  /* kill */
+
+	/*
+	 * Receive packets and dispatch them...
+	 * dispatch() will return only when we are shutting down.
+	 */
 	dispatch ();
 
-	/* Not reached */
+	log_info("Shutting down.");
+	dhcp_set_control_state(server_shutdown/*ignored*/, server_shutdown);
+
+	/* Let's return status code */
 	return 0;
 }
 #endif /* !UNIT_TEST */