[master] Implemented --dad-wait-time option for dhclient.

    Merged #36169

RELNOTES

@@ -133,6 +133,17 @@ by Eric Young (eay@cryptsoft.com).
   default location of the server configuration file.
   [ISC-Bugs #44765]
 
+- Added --dad-wait-time parameter to dhclient. It specifies the maximum time,
+  in seconds, that the client process should wait for the duplicate address
+  detection to complete before initiating DHCP requests. This value is
+  propagated to the dhclient script and the script is responsible for waiting
+  the specified amount of time or until DAD has completed. If the script does
+  not support it, specifying this parameter has no effect. The default value
+  is 0 which specifies that the script should not wait for DAD. With this
+  change the following scripts have been modified to support the new parameter:
+  freebsd, linux, macos, netbsd, openbsd.
+  [ISC-Bugs #36169]
+
 			Changes since 4.3.0 (bug fixes)
 
 - Tidy up several small tickets.

client/dhclient.8

@@ -134,6 +134,10 @@ dhclient - Dynamic Host Configuration Protocol Client
 .B -w
 ]
 [
+.B --dad-wait-time
+.I seconds
+]
+[
 .B -v
 ]
 [
@@ -409,6 +413,15 @@ overrides these default, with a value of either \fILL\fR or \fILLT\fR.
 Restore normal address query for IPv6. This implies \fB-6\fR.
 It is used to restore normal operation after using \fB-T\fR or \fB-P\fR.
 Multiple addresses can be requested with multiple \fB\-N\fR flags.
+.TP
+.BI \--dad-wait-time \ seconds
+Specify maximum time (in seconds) that the client should wait for the
+duplicate address detection (DAD) to complete on an interface. This
+value is propagated to the dhclient script in a dad_wait_time environment
+variable. If any of the IPv6 addresses on the interface are tentative
+(DAD is in progress), the script will wait for the specified number of
+seconds for DAD to complete. If the script ignores this variable the
+parameter has no effect.
 .PP
 .I Modifying default file locations:
 The following options can be used to modify the locations a client uses

client/dhclient.c

@@ -97,6 +97,7 @@ int wanted_ia_pd = 0;
 int require_all_ias = 0;	/* If the user requires all of the IAs to
 				   be available before accepting a lease
 				   0 = no, 1 = requries */
+int dad_wait_time = 0;
 char *mockup_relay = NULL;
 
 char *progname = NULL;
@@ -153,11 +154,12 @@ static const char use_v6command[] = "Command not used for DHCPv4: %s";
 #ifdef DHCPv6
 #ifdef DHCP4o6
 #define DHCLIENT_USAGE0 \
-"[-4|-6] [-SNTPRI1dvrxi] [-nw] -4o6 <port>]\n" \
-"                [-p <port>] [-D LL|LLT] \n"
+"[-4|-6] [-SNTPRI1dvrxi] [-nw] -4o6 <port>] [-p <port>]\n" \
+"                [-D LL|LLT] [--dad-wait-time seconds]\n"
 #else /* DHCP4o6 */
 #define DHCLIENT_USAGE0 \
-"[-4|-6] [-SNTPRI1dvrxi] [-nw] [-p <port>] [-D LL|LLT] \n"
+"[-4|-6] [-SNTPRI1dvrxi] [-nw] [-p <port>] [-D LL|LLT]\n" \
+"                [--dad-wait-time seconds]\n"
 #endif
 #else /* DHCPv6 */
 #define DHCLIENT_USAGE0 \
@@ -478,6 +480,15 @@ main(int argc, char **argv) {
 			local_family_set = 1;
 			local_family = AF_INET6;
 			require_all_ias = 1;
+		} else if (!strcmp(argv[i], "--dad-wait-time")) {
+			if (++i == argc) {
+				usage(use_noarg, argv[i-1]);
+			}
+			dad_wait_time = (int)strtol(argv[i], &s, 10);
+			if (errno || (*s != '\0') || (dad_wait_time < 0)) {
+				usage("Invalid value for --dad-wait-time: %s", argv[i]);
+			}
+
 #endif /* DHCPv6 */
 		} else if (!strcmp(argv[i], "-D")) {
 			duid_v4 = 1;
@@ -3930,6 +3941,8 @@ void script_init (client, reason, medium)
 
 		client_envadd (client, "", "reason", "%s", reason);
 		client_envadd (client, "", "pid", "%ld", (long int)getpid ());
+		client_envadd (client, "", "dad_wait_time", "%ld",
+					   (long int)dad_wait_time);
 	}
 }
 

client/scripts/freebsd

@@ -335,6 +335,42 @@ if [ ${reason} = PREINIT6 ] ; then
 
   # XXX: Remove any stale addresses from aborted clients.
 
+  # We need to give the kernel some time to active interface
+  interface_up_wait_time=5
+  for i in $(seq 0 ${interface_up_wait_time})
+  do
+      ifconfig ${interface} | grep inactive >/dev/null 2>&1
+      if [ $? -ne 0 ]; then
+          break;
+      fi
+      sleep 1
+  done
+
+  # Wait for duplicate address detection for this interface if the
+  # --dad-wait-time parameter has been specified and is greater than
+  # zero.
+  if [ ${dad_wait_time} -gt 0 ]; then
+      # Check if any IPv6 address on this interface is marked as
+      # tentative.
+      ifconfig ${interface} | grep inet6 | grep tentative \
+          >/dev/null 2>&1
+      if [ $? -eq 0 ]; then
+          # Wait for duplicate address detection to complete or for
+          # the timeout specified as --dad-wait-time.
+          for i in $(seq 0 $dad_wait_time)
+          do
+              # We're going to poll for the tentative flag every second.
+              sleep 1
+              ifconfig ${interface} | grep inet6 | grep tentative \
+                  >/dev/null 2>&1
+              if [ $? -ne 0 ]; then
+                  break;
+              fi
+          done
+      fi
+  fi
+
+
   exit_with_hooks 0
 fi
 

client/scripts/linux

@@ -248,9 +248,44 @@ if [ x$reason = xPREINIT6 ] ; then
   # Ensure interface is up.
   ${ip} link set ${interface} up
 
+  # We need to give the kernel some time to active interface
+  interface_up_wait_time=5
+  for i in $(seq 0 ${interface_up_wait_time})
+  do
+      ifconfig ${interface} | grep RUNNING >/dev/null 2>&1
+      if [ $? -eq 0 ]; then
+          break;
+      fi
+      sleep 1
+  done
+
   # Remove any stale addresses from aborted clients.
   ${ip} -f inet6 addr flush dev ${interface} scope global permanent
 
+  # Wait for duplicate address detection for this interface if the
+  # --dad-wait-time parameter has been specified and is greater than
+  # zero.
+  if [ ${dad_wait_time} -gt 0 ]; then
+      # Check if any IPv6 address on this interface is marked as
+      # tentative.
+      ${ip} addr show ${interface} | grep inet6 | grep tentative \
+          &> /dev/null
+      if [ $? -eq 0 ]; then
+          # Wait for duplicate address detection to complete or for
+          # the timeout specified as --dad-wait-time.
+          for i in $(seq 0 $dad_wait_time)
+          do
+              # We're going to poll for the tentative flag every second.
+              sleep 1
+              ${ip} addr show ${interface} | grep inet6 | grep tentative \
+                  &> /dev/null
+              if [ $? -ne 0 ]; then
+                  break;
+              fi
+          done
+      fi
+  fi
+
   exit_with_hooks 0
 fi
 

client/scripts/macos

@@ -144,8 +144,43 @@ if [ x$reason = xPREINIT6 ]; then
   # Ensure interface is up.
   ifconfig ${interface} up
 
+  # We need to give the kernel some time to active interface
+  interface_up_wait_time=5
+  for i in $(seq 0 ${interface_up_wait_time})
+  do
+      ifconfig ${interface} | grep inactive &> /dev/null
+      if [ $? -ne 0 ]; then
+          break;
+      fi
+      sleep 1
+  done
+
   # XXX: Remove any stale addresses from aborted clients.
 
+  # Wait for duplicate address detection for this interface if the
+  # --dad-wait-time parameter has been specified and is greater than
+  # zero.
+  if [ ${dad_wait_time} -gt 0 ]; then
+      # Check if any IPv6 address on this interface is marked as
+      # tentative.
+      ifconfig ${interface} | grep inet6 | grep tentative \
+          &> /dev/null
+      if [ $? -eq 0 ]; then
+          # Wait for duplicate address detection to complete or for
+          # the timeout specified as --dad-wait-time.
+          for i in $(seq 0 $dad_wait_time)
+          do
+              # We're going to poll for the tentative flag every second.
+              sleep 1
+              ifconfig ${interface} | grep inet6 | grep tentative \
+                  &> /dev/null
+              if [ $? -ne 0 ]; then
+                  break;
+              fi
+          done
+      fi
+  fi
+
   exit_with_hooks 0
 fi
 

client/scripts/netbsd

@@ -265,6 +265,41 @@ if [ ${reason} = PREINIT6 ] ; then
 
   # XXX: Remove any stale addresses from aborted clients.
 
+  # We need to give the kernel some time to active interface
+  interface_up_wait_time=5
+  for i in $(seq 0 ${interface_up_wait_time})
+  do
+      ifconfig ${interface} | grep inactive >/dev/null 2>&1
+      if [ $? -ne 0 ]; then
+          break;
+      fi
+      sleep 1
+  done
+
+  # Wait for duplicate address detection for this interface if the
+  # --dad-wait-time parameter has been specified and is greater than
+  # zero.
+  if [ ${dad_wait_time} -gt 0 ]; then
+      # Check if any IPv6 address on this interface is marked as
+      # tentative.
+      ifconfig ${interface} | grep inet6 | grep tentative \
+          >/dev/null 2>&1
+      if [ $? -eq 0 ]; then
+          # Wait for duplicate address detection to complete or for
+          # the timeout specified as --dad-wait-time.
+          for i in $(seq 0 $dad_wait_time)
+          do
+              # We're going to poll for the tentative flag every second.
+              sleep 1
+              ifconfig ${interface} | grep inet6 | grep tentative \
+                  >/dev/null 2>&1
+              if [ $? -ne 0 ]; then
+                  break;
+              fi
+          done
+      fi
+  fi
+
   exit_with_hooks 0
 fi
 

client/scripts/openbsd

@@ -259,6 +259,41 @@ if [ ${reason} = PREINIT6 ] ; then
 
   # XXX: Remove any stale addresses from aborted clients.
 
+  # We need to give the kernel some time to active interface
+  interface_up_wait_time=5
+  for i in $(seq 0 ${interface_up_wait_time})
+  do
+      ifconfig ${interface} | grep inactive >/dev/null 2>&1
+      if [ $? -ne 0 ]; then
+          break;
+      fi
+      sleep 1
+  done
+
+  # Wait for duplicate address detection for this interface if the
+  # --dad-wait-time parameter has been specified and is greater than
+  # zero.
+  if [ ${dad_wait_time} -gt 0 ]; then
+      # Check if any IPv6 address on this interface is marked as
+      # tentative.
+      ifconfig ${interface} | grep inet6 | grep tentative \
+          >/dev/null 2>&1
+      if [ $? -eq 0 ]; then
+          # Wait for duplicate address detection to complete or for
+          # the timeout specified as --dad-wait-time.
+          for i in $(seq 0 $dad_wait_time)
+          do
+              # We're going to poll for the tentative flag every second.
+              sleep 1
+              ifconfig ${interface} | grep inet6 | grep tentative \
+                  >/dev/null 2>&1
+              if [ $? -ne 0 ]; then
+                  break;
+              fi
+          done
+      fi
+  fi
+
   exit_with_hooks 0
 fi