sd-network: IPv4 link-local support [v2]

Implements IPv4LL with respect to RFC 3927
(http://tools.ietf.org/rfc/rfc3927.txt) and integrates it
with networkd. Majority of the IPv4LL state machine is
taken from avahi (http://avahi.org/) project's autoip.

IPv4LL can be enabled by IPv4LL=yes under [Network]
section of .network file.

IPv4LL works independent of DHCP but if DHCP lease is
aquired, then LL address will be dropped.

[tomegun: removed a trailing newline and a compiler warning]

1 files changed, 85 insertions, 0 deletions

diff --git a/src/network/networkd-route.c b/src/network/networkd-route.c
index 46a4537196..0cb7239ca0 100644
--- a/src/network/networkd-route.c
+++ b/src/network/networkd-route.c
@@ -48,6 +48,7 @@ int route_new_static(Network *network, unsigned section, Route **ret) {
                 return -ENOMEM;
 
         route->family = AF_UNSPEC;
+        route->scope = RT_SCOPE_UNIVERSE;
 
         route->network = network;
 
@@ -72,6 +73,7 @@ int route_new_dynamic(Route **ret) {
                 return -ENOMEM;
 
         route->family = AF_UNSPEC;
+        route->scope = RT_SCOPE_UNIVERSE;
 
         *ret = route;
         route = NULL;
@@ -94,6 +96,77 @@ void route_free(Route *route) {
         free(route);
 }
 
+int route_drop(Route *route, Link *link,
+               sd_rtnl_message_handler_t callback) {
+        _cleanup_rtnl_message_unref_ sd_rtnl_message *req = NULL;
+        int r;
+
+        assert(link);
+        assert(link->manager);
+        assert(link->manager->rtnl);
+        assert(link->ifindex > 0);
+        assert(route->family == AF_INET || route->family == AF_INET6);
+
+        r = sd_rtnl_message_new_route(link->manager->rtnl, &req,
+                                      RTM_DELROUTE, route->family);
+        if (r < 0) {
+                log_error("Could not create RTM_DELROUTE message: %s", strerror(-r));
+                return r;
+        }
+
+        if (route->family == AF_INET)
+                r = sd_rtnl_message_append_in_addr(req, RTA_GATEWAY, &route->in_addr.in);
+        else if (route->family == AF_INET6)
+                r = sd_rtnl_message_append_in6_addr(req, RTA_GATEWAY, &route->in_addr.in6);
+        if (r < 0) {
+                log_error("Could not append RTA_GATEWAY attribute: %s", strerror(-r));
+                return r;
+        }
+
+        if (route->dst_prefixlen) {
+                if (route->family == AF_INET)
+                        r = sd_rtnl_message_append_in_addr(req, RTA_DST, &route->dst_addr.in);
+                else if (route->family == AF_INET6)
+                        r = sd_rtnl_message_append_in6_addr(req, RTA_DST, &route->dst_addr.in6);
+                if (r < 0) {
+                        log_error("Could not append RTA_DST attribute: %s", strerror(-r));
+                        return r;
+                }
+
+                r = sd_rtnl_message_route_set_dst_prefixlen(req, route->dst_prefixlen);
+                if (r < 0) {
+                        log_error("Could not set destination prefix length: %s", strerror(-r));
+                        return r;
+                }
+        }
+
+        r = sd_rtnl_message_route_set_scope(req, route->scope);
+        if (r < 0) {
+                log_error("Could not set scope: %s", strerror(-r));
+                return r;
+        }
+
+        r = sd_rtnl_message_append_u32(req, RTA_PRIORITY, route->metrics);
+        if (r < 0) {
+                log_error("Could not append RTA_PRIORITY attribute: %s", strerror(-r));
+                return r;
+        }
+
+        r = sd_rtnl_message_append_u32(req, RTA_OIF, link->ifindex);
+        if (r < 0) {
+                log_error("Could not append RTA_OIF attribute: %s", strerror(-r));
+                return r;
+        }
+
+        r = sd_rtnl_call_async(link->manager->rtnl, req, callback, link, 0, NULL);
+        if (r < 0) {
+                log_error("Could not send rtnetlink message: %s", strerror(-r));
+                return r;
+        }
+
+        return 0;
+}
+
 int route_configure(Route *route, Link *link,
                     sd_rtnl_message_handler_t callback) {
         _cleanup_rtnl_message_unref_ sd_rtnl_message *req = NULL;
@@ -138,6 +211,18 @@ int route_configure(Route *route, Link *link,
                 }
         }
 
+        r = sd_rtnl_message_route_set_scope(req, route->scope);
+        if (r < 0) {
+                log_error("Could not set scope: %s", strerror(-r));
+                return r;
+        }
+
+        r = sd_rtnl_message_append_u32(req, RTA_PRIORITY, route->metrics);
+        if (r < 0) {
+                log_error("Could not append RTA_PRIORITY attribute: %s", strerror(-r));
+                return r;
+        }
+
         r = sd_rtnl_message_append_u32(req, RTA_OIF, link->ifindex);
         if (r < 0) {
                 log_error("Could not append RTA_OIF attribute: %s", strerror(-r));