udhcp6: read_interface should save link-local ipv6 address

Patch is based on work by tiggerswelt.net. They say:
"Using this patch it was no problem to acquire an IPv6-Address via DHCPv6
using ISC DHCPD6 on server-side."

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

3 files changed, 71 insertions, 5 deletions

diff --git a/networking/udhcp/d6_common.h b/networking/udhcp/d6_common.h
index eb211ea0f..f7cfa4ab8 100644
--- a/networking/udhcp/d6_common.h
+++ b/networking/udhcp/d6_common.h
@@ -91,10 +91,14 @@ struct client6_data_t {
         struct d6_option *ia_na;
         char **env_ptr;
         unsigned env_idx;
+        /* link-local IPv6 address */
+        struct in6_addr ll_ip6;
 };
 
 #define client6_data (*(struct client6_data_t*)(&bb_common_bufsiz1[COMMON_BUFSIZE - sizeof(struct client6_data_t)]))
 
+int FAST_FUNC d6_read_interface(const char *interface, int *ifindex, struct in6_addr *nip6, uint8_t *mac);
+
 int FAST_FUNC d6_listen_socket(int port, const char *inf);
 
 int FAST_FUNC d6_recv_kernel_packet(
diff --git a/networking/udhcp/d6_dhcpc.c b/networking/udhcp/d6_dhcpc.c
index bea589d71..95f8939b4 100644
--- a/networking/udhcp/d6_dhcpc.c
+++ b/networking/udhcp/d6_dhcpc.c
@@ -311,7 +311,7 @@ static int d6_mcast_from_client_config_ifindex(struct d6_packet *packet, uint8_t
 
         return d6_send_raw_packet(
                 packet, (end - (uint8_t*) packet),
-                /*src*/ NULL, CLIENT_PORT6,
+                /*src*/ &client6_data.ll_ip6, CLIENT_PORT6,
                 /*dst*/ (struct in6_addr*)FF02__1_2, SERVER_PORT6, MAC_BCAST_ADDR,
                 client_config.ifindex
         );
@@ -1003,9 +1003,9 @@ int udhcpc6_main(int argc UNUSED_PARAM, char **argv)
                 udhcp_str2optset(optstr, &client_config.options);
         }
 
-        if (udhcp_read_interface(client_config.interface,
+        if (d6_read_interface(client_config.interface,
                         &client_config.ifindex,
-                        NULL,
+                        &client6_data.ll_ip6,
                         client_config.client_mac)
         ) {
                 return 1;
@@ -1106,13 +1106,14 @@ int udhcpc6_main(int argc UNUSED_PARAM, char **argv)
                          * or if the status of the bridge changed).
                          * Refresh ifindex and client_mac:
                          */
-                        if (udhcp_read_interface(client_config.interface,
+                        if (d6_read_interface(client_config.interface,
                                         &client_config.ifindex,
-                                        NULL,
+                                        &client6_data.ll_ip6,
                                         client_config.client_mac)
                         ) {
                                 goto ret0; /* iface is gone? */
                         }
+
                         memcpy(clientid_mac_ptr, client_config.client_mac, 6);
 
                         /* We will restart the wait in any case */
diff --git a/networking/udhcp/d6_socket.c b/networking/udhcp/d6_socket.c
index 910f296a3..930e5e4f5 100644
--- a/networking/udhcp/d6_socket.c
+++ b/networking/udhcp/d6_socket.c
@@ -7,6 +7,67 @@
 #include "common.h"
 #include "d6_common.h"
 #include <net/if.h>
+#include <ifaddrs.h>
+#include <netpacket/packet.h>
+
+int FAST_FUNC d6_read_interface(const char *interface, int *ifindex, struct in6_addr *nip6, uint8_t *mac)
+{
+        int retval = 3;
+        struct ifaddrs *ifap, *ifa;
+
+        getifaddrs(&ifap);
+
+        for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
+                struct sockaddr_in6 *sip6;
+
+                if (!ifa->ifa_addr || (strcmp(ifa->ifa_name, interface) != 0))
+                        continue;
+
+                sip6 = (struct sockaddr_in6*)(ifa->ifa_addr);
+
+                if (ifa->ifa_addr->sa_family == AF_PACKET) {
+                        struct sockaddr_ll *sll = (struct sockaddr_ll*)(ifa->ifa_addr);
+                        memcpy(mac, sll->sll_addr, 6);
+                        log1("MAC %02x:%02x:%02x:%02x:%02x:%02x", mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
+                        log1("adapter index %d", sll->sll_ifindex);
+                        *ifindex = sll->sll_ifindex;
+                        retval &= (0xf - (1<<0));
+                }
+#if 0
+                if (ifa->ifa_addr->sa_family == AF_INET) {
+                        *nip = ((struct sockaddr_in *)ifa->ifa_addr)->sin_addr.s_addr;
+                        log1("IP %s", inet_ntoa(((struct sockaddr_in *)ifa->ifa_addr)->sin_addr));
+                }
+#endif
+                if (ifa->ifa_addr->sa_family == AF_INET6
+                 && IN6_IS_ADDR_LINKLOCAL(&sip6->sin6_addr)
+                ) {
+                        *nip6 = sip6->sin6_addr; /* struct copy */
+                        log1(
+                                "IPv6 %02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x",
+                                nip6->s6_addr[0], nip6->s6_addr[1],
+                                nip6->s6_addr[2], nip6->s6_addr[3],
+                                nip6->s6_addr[4], nip6->s6_addr[5],
+                                nip6->s6_addr[6], nip6->s6_addr[7],
+                                nip6->s6_addr[8], nip6->s6_addr[9],
+                                nip6->s6_addr[10], nip6->s6_addr[11],
+                                nip6->s6_addr[12], nip6->s6_addr[13],
+                                nip6->s6_addr[14], nip6->s6_addr[15]
+                        );
+                        retval &= (0xf - (1<<1));
+                }
+        }
+
+        freeifaddrs(ifap);
+        if (retval == 0)
+                return retval;
+
+        if (retval & (1<<0))
+                bb_error_msg("can't get %s", "MAC");
+        if (retval & (1<<1))
+                bb_error_msg("can't get %s", "link-local IPv6 address");
+        return -1;
+}
 
 int FAST_FUNC d6_listen_socket(int port, const char *inf)
 {