Add --force-fast-ra option.

CHANGELOG

@@ -90,6 +90,8 @@ version 2.67
             smallest valid dhcp-range is sent. Thanks to Uwe Schindler 
 	    for suggesting this.
 
+	    Add --force-fast-ra option. Another thanks to Uwe Schindler.  
+
 
 version 2.66
             Add the ability to act as an authoritative DNS

man/dnsmasq.8

@@ -1487,6 +1487,12 @@ the relevant link-local address of the machine running dnsmasq is sent
 as recursive DNS server. If provided, the DHCPv6 options dns-server and
 domain-search are used for RDNSS and DNSSL.
 .TP
+.B --force-fast-ra
+Normally, dnsmasq advertises a new IPv6 prefix frequently (every 10 seconds or so) for the first minute, and then
+drops back to sending "maintenance" advertisements every 10 minutes or so. This option forces dnsmasq to be always in 
+frequent RA mode. It's a bug workaround for mobile devices which go deaf to RAs during sleep and therefore 
+lose conectivity; with frequent RAs they recover in a reasonable time after wakeup.
+.TP
 .B --enable-tftp
 Enable the TFTP server function. This is deliberately limited to that
 needed to net-boot a client. Only reading is allowed; the tsize and

src/dnsmasq.h

@@ -221,7 +221,8 @@ struct event_desc {
 #define OPT_TFTP_LC        38
 #define OPT_CLEVERBIND     39
 #define OPT_TFTP           40
-#define OPT_LAST           41
+#define OPT_FAST_RA        41
+#define OPT_LAST           42
 
 /* extra flags for my_syslog, we use a couple of facilities since they are known 
    not to occupy the same bits as priorities, no matter how syslog.h is set up. */

src/option.c

@@ -132,6 +132,7 @@ struct myoption {
 #ifdef OPTION6_PREFIX_CLASS 
 #define LOPT_PREF_CLSS 321
 #endif
+#define LOPT_FAST_RA   322
 
 #ifdef HAVE_GETOPT_LONG
 static const struct option opts[] =  
@@ -269,6 +270,7 @@ static const struct myoption opts[] =
 #ifdef OPTION6_PREFIX_CLASS 
     { "dhcp-prefix-class", 1, 0, LOPT_PREF_CLSS },
 #endif
+    { "force-fast-ra", 0, 0, LOPT_FAST_RA },
     { NULL, 0, 0, 0 }
   };
 
@@ -397,6 +399,7 @@ static struct {
   { LOPT_CONNTRACK, OPT_CONNTRACK, NULL, gettext_noop("Copy connection-track mark from queries to upstream connections."), NULL },
   { LOPT_FQDN, OPT_FQDN_UPDATE, NULL, gettext_noop("Allow DHCP clients to do their own DDNS updates."), NULL },
   { LOPT_RA, OPT_RA, NULL, gettext_noop("Send router-advertisements for interfaces doing DHCPv6"), NULL },
+  { LOPT_FAST_RA, OPT_FAST_RA, NULL, gettext_noop("Always send frequent router-advertisements"), NULL },
   { LOPT_DUID, ARG_ONE, "<enterprise>,<duid>", gettext_noop("Specify DUID_EN-type DHCPv6 server DUID"), NULL },
   { LOPT_HOST_REC, ARG_DUP, "<name>,<address>", gettext_noop("Specify host (A/AAAA and PTR) records"), NULL },
   { LOPT_RR, ARG_DUP, "<name>,<RR-number>,[<data>]", gettext_noop("Specify arbitrary DNS resource record"), NULL },

src/radv.c

@@ -652,7 +652,7 @@ static int iface_search(struct in6_addr *local,  int prefix,
  
 static void new_timeout(struct dhcp_context *context, time_t now)
 {
-  if (difftime(now, context->ra_short_period_start) < 60.0)
+  if (difftime(now, context->ra_short_period_start) < 60.0 || option_bool(OPT_FAST_RA))
     /* range 5 - 20 */
     context->ra_time = now + 5 + (rand16()/4400);
   else