netlink: add support for getting interface linklocal

Add support for getting interface linklocal address. This is needed to
make sure an interface have a valid link local address and such address
is not TENTATIVE. With these info we can check if an interface is ready
to accept packets.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>

diff --git a/src/netlink.c b/src/netlink.c
index 9b9fdb862b0aef8343478ebb4095e2fbe384b88d..c2b9576a59142a17c7add479752d4c3f6697c302 100644 (file)
--- a/src/netlink.c
+++ b/src/netlink.c
@@ -765,6 +765,145 @@ out:
 }
 
 
+static int cb_linklocal_valid(struct nl_msg *msg, void *arg)
+{
+       struct addr_info *ctxt = (struct addr_info *)arg;
+       struct odhcpd_ipaddr *addrs = *(ctxt->addrs);
+       struct nlmsghdr *hdr = nlmsg_hdr(msg);
+       struct ifaddrmsg *ifa;
+       struct nlattr *nla[__IFA_MAX], *nla_addr = NULL;
+       struct in6_addr addr;
+
+       if (hdr->nlmsg_type != RTM_NEWADDR)
+               return NL_SKIP;
+
+       ifa = NLMSG_DATA(hdr);
+       if (ifa->ifa_scope != RT_SCOPE_LINK ||
+                       (ctxt->af != ifa->ifa_family) ||
+                       (ctxt->ifindex && ifa->ifa_index != (unsigned)ctxt->ifindex))
+               return NL_SKIP;
+
+       nlmsg_parse(hdr, sizeof(*ifa), nla, __IFA_MAX - 1, NULL);
+
+       switch (ifa->ifa_family) {
+       case AF_INET6:
+               if (nla[IFA_ADDRESS])
+                       nla_addr = nla[IFA_ADDRESS];
+               break;
+
+       default:
+               break;
+       }
+       if (!nla_addr)
+               return NL_SKIP;
+
+       nla_memcpy(&addr, nla_addr, sizeof(addr));
+
+       if (!IN6_IS_ADDR_LINKLOCAL(&addr))
+               return NL_SKIP;
+
+       addrs = realloc(addrs, sizeof(*addrs)*(ctxt->ret + 1));
+       if (!addrs)
+               return NL_SKIP;
+
+       memset(&addrs[ctxt->ret], 0, sizeof(addrs[ctxt->ret]));
+
+       addrs = realloc(addrs, sizeof(*addrs)*(ctxt->ret + 1));
+       if (!addrs)
+               return NL_SKIP;
+
+
+       memcpy(&addrs[ctxt->ret].addr, &addr, sizeof(addrs[ctxt->ret].addr));
+
+       if (ifa->ifa_flags & IFA_F_TENTATIVE)
+               addrs[ctxt->ret].tentative = true;
+
+       ctxt->ret++;
+       *(ctxt->addrs) = addrs;
+
+       return NL_OK;
+}
+
+
+static int cb_linklocal_finish(_unused struct nl_msg *msg, void *arg)
+{
+       struct addr_info *ctxt = (struct addr_info *)arg;
+
+       ctxt->pending = 0;
+
+       return NL_STOP;
+}
+
+
+static int cb_linklocal_error(_unused struct sockaddr_nl *nla, struct nlmsgerr *err,
+               void *arg)
+{
+       struct addr_info *ctxt = (struct addr_info *)arg;
+
+       ctxt->pending = 0;
+       ctxt->ret = err->error;
+
+       return NL_STOP;
+}
+
+
+/* Detect a link local IPV6-address currently assigned to the given interface */
+ssize_t netlink_get_interface_linklocal(int ifindex, struct odhcpd_ipaddr **addrs)
+{
+       struct nl_msg *msg;
+       struct ifaddrmsg ifa = {
+               .ifa_family = AF_INET6,
+               .ifa_prefixlen = 0,
+               .ifa_flags = 0,
+               .ifa_scope = 0,
+               .ifa_index = ifindex, };
+       struct nl_cb *cb = nl_cb_alloc(NL_CB_DEFAULT);
+       struct addr_info ctxt = {
+               .ifindex = ifindex,
+               .af = AF_INET6,
+               .addrs = addrs,
+               .ret = 0,
+               .pending = 1,
+       };
+
+       if (!cb) {
+               ctxt.ret = -1;
+               goto out;
+       }
+
+       msg = nlmsg_alloc_simple(RTM_GETADDR, NLM_F_REQUEST | NLM_F_DUMP);
+
+       if (!msg) {
+               ctxt.ret = - 1;
+               goto out;
+       }
+
+       nlmsg_append(msg, &ifa, sizeof(ifa), 0);
+
+       nl_cb_set(cb, NL_CB_VALID, NL_CB_CUSTOM, cb_linklocal_valid, &ctxt);
+       nl_cb_set(cb, NL_CB_FINISH, NL_CB_CUSTOM, cb_linklocal_finish, &ctxt);
+       nl_cb_err(cb, NL_CB_CUSTOM, cb_linklocal_error, &ctxt);
+
+       ctxt.ret = nl_send_auto_complete(rtnl_socket, msg);
+       if (ctxt.ret < 0)
+               goto free;
+
+       ctxt.ret = 0;
+       while (ctxt.pending > 0)
+               nl_recvmsgs(rtnl_socket, cb);
+
+       if (ctxt.ret <= 0)
+               goto free;
+
+free:
+       nlmsg_free(msg);
+out:
+       nl_cb_put(cb);
+
+       return ctxt.ret;
+}
+
+
 struct neigh_info {
        int ifindex;
        int pending;

diff --git a/src/odhcpd.h b/src/odhcpd.h
index bd61b012ff3fa89d0289946408d16513a2921b3c..420d2a7dd78f0310adce5d311c3539276e745eba 100644 (file)
--- a/src/odhcpd.h
+++ b/src/odhcpd.h
@@ -448,6 +448,7 @@ void dhcpv6_ia_write_statefile(void);
 int netlink_add_netevent_handler(struct netevent_handler *hdlr);
 ssize_t netlink_get_interface_addrs(const int ifindex, bool v6,
                struct odhcpd_ipaddr **addrs);
+ssize_t netlink_get_interface_linklocal(int ifindex, struct odhcpd_ipaddr **addrs);
 int netlink_get_interface_proxy_neigh(int ifindex, const struct in6_addr *addr);
 int netlink_setup_route(const struct in6_addr *addr, const int prefixlen,
                const int ifindex, const struct in6_addr *gw,