send router solicitation for ipv6 address autoconf v2

Many routers have long router advertisment interval configured by
default. The Neighbor Discovery protocol (RFC4861) has defined default
MaxRtrAdvInterval value as 600 seconds and
MinRtrAdvInterval as 0.33*MaxRtrAdvInterval. This makes
net_ipv6_autoconf fails more often than not as currently it passively
listens the RA message to perfom address autoconfiguration.

This patch tries to send router solicitation to overcome the problem of
long RA interval.

v2:
use cpu_to_be macro for network byte order conversion
add missing error handling

grub-core/net/icmp6.c

@@ -72,6 +72,11 @@ struct neighbour_advertise
   grub_uint64_t target[2];
 } GRUB_PACKED;
 
+struct router_solicit
+{
+  grub_uint32_t reserved;
+} GRUB_PACKED;
+
 enum
   {
     FLAG_SLAAC = 0x40
@@ -81,6 +86,7 @@ enum
   {
     ICMP6_ECHO = 128,
     ICMP6_ECHO_REPLY = 129,
+    ICMP6_ROUTER_SOLICIT = 133,
     ICMP6_ROUTER_ADVERTISE = 134,
     ICMP6_NEIGHBOUR_SOLICIT = 135,
     ICMP6_NEIGHBOUR_ADVERTISE = 136,
@@ -533,3 +539,80 @@ grub_net_icmp6_send_request (struct grub_net_network_level_interface *inf,
   grub_netbuff_free (nb);
   return err;
 }
+
+grub_err_t
+grub_net_icmp6_send_router_solicit (struct grub_net_network_level_interface *inf)
+{
+  struct grub_net_buff *nb;
+  grub_err_t err = GRUB_ERR_NONE;
+  grub_net_network_level_address_t multicast;
+  grub_net_link_level_address_t ll_multicast;
+  struct option_header *ohdr;
+  struct router_solicit *sol;
+  struct icmp_header *icmphr;
+
+  multicast.type = GRUB_NET_NETWORK_LEVEL_PROTOCOL_IPV6;
+  multicast.ipv6[0] = grub_cpu_to_be64 (0xff02ULL << 48);
+  multicast.ipv6[1] = grub_cpu_to_be64 (0x02ULL);
+
+  err = grub_net_link_layer_resolve (inf, &multicast, &ll_multicast);
+  if (err)
+    return err;
+
+  nb = grub_netbuff_alloc (sizeof (struct router_solicit)
+			   + sizeof (struct option_header)
+			   + 6
+			   + sizeof (struct icmp_header)
+			   + GRUB_NET_OUR_IPV6_HEADER_SIZE
+			   + GRUB_NET_MAX_LINK_HEADER_SIZE);
+  if (!nb)
+    return grub_errno;
+  err = grub_netbuff_reserve (nb,
+			      sizeof (struct router_solicit)
+			      + sizeof (struct option_header)
+			      + 6
+			      + sizeof (struct icmp_header)
+			      + GRUB_NET_OUR_IPV6_HEADER_SIZE
+			      + GRUB_NET_MAX_LINK_HEADER_SIZE);
+  if (err)
+    goto fail;
+
+  err = grub_netbuff_push (nb, 6);
+  if (err)
+    goto fail;
+
+  grub_memcpy (nb->data, inf->hwaddress.mac, 6);
+
+  err = grub_netbuff_push (nb, sizeof (*ohdr));
+  if (err)
+    goto fail;
+
+  ohdr = (struct option_header *) nb->data;
+  ohdr->type = OPTION_SOURCE_LINK_LAYER_ADDRESS;
+  ohdr->len = 1;
+
+  err = grub_netbuff_push (nb, sizeof (*sol));
+  if (err)
+    goto fail;
+
+  sol = (struct router_solicit *) nb->data;
+  sol->reserved = 0;
+
+  err = grub_netbuff_push (nb, sizeof (*icmphr));
+  if (err)
+    goto fail;
+
+  icmphr = (struct icmp_header *) nb->data;
+  icmphr->type = ICMP6_ROUTER_SOLICIT;
+  icmphr->code = 0;
+  icmphr->checksum = 0;
+  icmphr->checksum = grub_net_ip_transport_checksum (nb,
+						     GRUB_NET_IP_ICMPV6,
+						     &inf->address,
+						     &multicast);
+  err = grub_net_send_ip_packet (inf, &multicast, &ll_multicast, nb,
+				 GRUB_NET_IP_ICMPV6);
+ fail:
+  grub_netbuff_free (nb);
+  return err;
+}

grub-core/net/net.c

@@ -380,12 +380,14 @@ grub_cmd_ipv6_autoconf (struct grub_command *cmd __attribute__ ((unused)),
 
   for (interval = 200; interval < 10000; interval *= 2)
     {
-      /* FIXME: send router solicitation.  */
       int done = 1;
       for (j = 0; j < ncards; j++)
 	{
 	  if (slaacs[j]->slaac_counter)
 	    continue;
+	  err = grub_net_icmp6_send_router_solicit (ifaces[j]);
+	  if (err)
+	    err = GRUB_ERR_NONE;
 	  done = 0;
 	}
       if (done)

include/grub/net/ip.h

@@ -92,4 +92,6 @@ grub_err_t
 grub_net_icmp6_send_request (struct grub_net_network_level_interface *inf,
 			     const grub_net_network_level_address_t *proto_addr);
 
+grub_err_t
+grub_net_icmp6_send_router_solicit (struct grub_net_network_level_interface *inf);
 #endif