Add support for DHCP static route options

This adds support for DHCP options 33 and 121: Static Route and
Classless Static Route. To enable this feature, set UseRoutes=true
in .network file. Returned routes are added to the routing table.

5 files changed, 146 insertions, 2 deletions

diff --git a/src/network/networkd-link.c b/src/network/networkd-link.c
index 5d280b5b82..82e517e78c 100644
--- a/src/network/networkd-link.c
+++ b/src/network/networkd-link.c
@@ -402,6 +402,51 @@ static int route_handler(sd_rtnl *rtnl, sd_rtnl_message *m, void *userdata) {
         return 1;
 }
 
+static int link_set_dhcp_routes(Link *link) {
+        struct sd_dhcp_route *static_routes;
+        size_t static_routes_size;
+        int r;
+        unsigned i;
+
+        assert(link);
+
+        r = sd_dhcp_lease_get_routes(link->dhcp_lease, &static_routes, &static_routes_size);
+        if (r < 0) {
+                if (r != -ENOENT)
+                        log_warning_link(link, "DHCP error: %s", strerror(-r));
+                return r;
+        }
+
+        for (i = 0; i < static_routes_size; i++) {
+                _cleanup_route_free_ Route *route = NULL;
+
+                r = route_new_dynamic(&route);
+                if (r < 0) {
+                        log_error_link(link, "Could not allocate route: %s",
+                                       strerror(-r));
+                        return r;
+                }
+
+                route->family = AF_INET;
+                route->in_addr.in = static_routes[i].gw_addr;
+                route->dst_addr.in = static_routes[i].dst_addr;
+                route->dst_prefixlen = static_routes[i].dst_prefixlen;
+                route->metrics = DHCP_STATIC_ROUTE_METRIC;
+
+                r = route_configure(route, link, &route_handler);
+                if (r < 0) {
+                        log_warning_link(link,
+                                         "could not set host route: %s", strerror(-r));
+                        return r;
+                }
+
+                link_ref(link);
+                link->route_messages ++;
+        }
+
+        return 0;
+}
+
 static int link_enter_set_routes(Link *link) {
         Route *rt;
         int r;
@@ -525,6 +570,9 @@ static int link_enter_set_routes(Link *link) {
                         link_ref(link);
                         link->route_messages ++;
                 }
+
+                if (link->network->dhcp_routes)
+                        link_set_dhcp_routes(link);
         }
 
         if (link->route_messages == 0) {
@@ -901,12 +949,11 @@ static int link_set_mtu(Link *link, uint32_t mtu) {
 
 static int dhcp_lease_lost(Link *link) {
         _cleanup_address_free_ Address *address = NULL;
-        _cleanup_route_free_ Route *route_gw = NULL;
-        _cleanup_route_free_ Route *route = NULL;
         struct in_addr addr;
         struct in_addr netmask;
         struct in_addr gateway;
         unsigned prefixlen;
+        unsigned i;
         int r;
 
         assert(link);
@@ -914,10 +961,36 @@ static int dhcp_lease_lost(Link *link) {
 
         log_warning_link(link, "DHCP lease lost");
 
+        if (link->network->dhcp_routes) {
+                struct sd_dhcp_route *routes;
+                size_t routes_size;
+
+                r = sd_dhcp_lease_get_routes(link->dhcp_lease, &routes, &routes_size);
+                if (r >= 0) {
+                        for (i = 0; i < routes_size; i++) {
+                                _cleanup_route_free_ Route *route = NULL;
+
+                                r = route_new_dynamic(&route);
+                                if (r >= 0) {
+                                        route->family = AF_INET;
+                                        route->in_addr.in = routes[i].gw_addr;
+                                        route->dst_addr.in = routes[i].dst_addr;
+                                        route->dst_prefixlen = routes[i].dst_prefixlen;
+
+                                        route_drop(route, link, &route_drop_handler);
+                                        link_ref(link);
+                                }
+                        }
+                }
+        }
+
         r = address_new_dynamic(&address);
         if (r >= 0) {
                 r = sd_dhcp_lease_get_router(link->dhcp_lease, &gateway);
                 if (r >= 0) {
+                        _cleanup_route_free_ Route *route_gw = NULL;
+                        _cleanup_route_free_ Route *route = NULL;
+
                         r = route_new_dynamic(&route_gw);
                         if (r >= 0) {
                                 route_gw->family = AF_INET;
@@ -1952,6 +2025,14 @@ static int link_configure(Link *link) {
                         if (r < 0)
                                 return r;
                 }
+                if (link->network->dhcp_routes) {
+                        r = sd_dhcp_client_set_request_option(link->dhcp_client, DHCP_OPTION_STATIC_ROUTE);
+                        if (r < 0)
+                                return r;
+                        r = sd_dhcp_client_set_request_option(link->dhcp_client, DHCP_OPTION_CLASSLESS_STATIC_ROUTE);
+                        if (r < 0)
+                                return r;
+                }
         }
 
         if (link->network->dhcp_server) {
diff --git a/src/network/networkd-network-gperf.gperf b/src/network/networkd-network-gperf.gperf
index c8610d14f4..b6d52e7335 100644
--- a/src/network/networkd-network-gperf.gperf
+++ b/src/network/networkd-network-gperf.gperf
@@ -53,4 +53,5 @@ DHCPv4.UseDNS,               config_parse_bool,                  0,
 DHCPv4.UseMTU,               config_parse_bool,                  0,                             offsetof(Network, dhcp_mtu)
 DHCPv4.UseHostname,          config_parse_bool,                  0,                             offsetof(Network, dhcp_hostname)
 DHCPv4.UseDomainName,        config_parse_bool,                  0,                             offsetof(Network, dhcp_domainname)
+DHCPv4.UseRoutes,            config_parse_bool,                  0,                             offsetof(Network, dhcp_routes)
 DHCPv4.CriticalConnection,   config_parse_bool,                  0,                             offsetof(Network, dhcp_critical)
diff --git a/src/network/networkd-network.c b/src/network/networkd-network.c
index 8e7cdf670b..f60f7c812c 100644
--- a/src/network/networkd-network.c
+++ b/src/network/networkd-network.c
@@ -89,6 +89,7 @@ static int network_load_one(Manager *manager, const char *filename) {
         network->dhcp_dns = true;
         network->dhcp_hostname = true;
         network->dhcp_domainname = true;
+        network->dhcp_routes = true;
 
         r = config_parse(NULL, filename, file, "Match\0Network\0Address\0Route\0DHCPv4\0", config_item_perf_lookup,
                         (void*) network_network_gperf_lookup, false, false, network);
diff --git a/src/network/networkd.h b/src/network/networkd.h
index 67f70d9e60..11268de70d 100644
--- a/src/network/networkd.h
+++ b/src/network/networkd.h
@@ -42,6 +42,7 @@
 
 #define CACHE_INFO_INFINITY_LIFE_TIME 0xFFFFFFFFU
 #define VXLAN_VID_MAX (1u << 24) - 1
+#define DHCP_STATIC_ROUTE_METRIC 1024
 
 typedef struct NetDev NetDev;
 typedef struct Network Network;
@@ -169,6 +170,7 @@ struct Network {
         bool dhcp_hostname;
         bool dhcp_domainname;
         bool dhcp_critical;
+        bool dhcp_routes;
         bool ipv4ll;
 
         bool dhcp_server;
diff --git a/src/network/test-network.c b/src/network/test-network.c
index eb6ebe70b3..75e70fae14 100644
--- a/src/network/test-network.c
+++ b/src/network/test-network.c
@@ -21,6 +21,7 @@
 
 #include "networkd.h"
 #include "network-internal.h"
+#include "dhcp-lease-internal.h"
 
 static void test_deserialize_in_addr(void) {
         _cleanup_free_ struct in_addr *addresses = NULL;
@@ -53,6 +54,63 @@ static void test_deserialize_in_addr(void) {
         assert_se(!memcmp(&f, &addresses6[2], sizeof(struct in6_addr)));
 }
 
+static void test_deserialize_dhcp_routes(void) {
+        size_t size, allocated;
+
+        {
+                _cleanup_free_ struct sd_dhcp_route *routes = NULL;
+                assert_se(deserialize_dhcp_routes(&routes, &size, &allocated, "") >= 0);
+                assert_se(size == 0);
+        }
+
+        {
+                /* no errors */
+                _cleanup_free_ struct sd_dhcp_route *routes = NULL;
+                const char *routes_string = "192.168.0.0/16,192.168.0.1 10.1.2.0/24,10.1.2.1 0.0.0.0/0,10.0.1.1";
+
+                assert_se(deserialize_dhcp_routes(&routes, &size, &allocated, routes_string) >= 0);
+
+                assert_se(size == 3);
+                assert_se(routes[0].dst_addr.s_addr == inet_addr("192.168.0.0"));
+                assert_se(routes[0].gw_addr.s_addr == inet_addr("192.168.0.1"));
+                assert_se(routes[0].dst_prefixlen == 16);
+
+                assert_se(routes[1].dst_addr.s_addr == inet_addr("10.1.2.0"));
+                assert_se(routes[1].gw_addr.s_addr == inet_addr("10.1.2.1"));
+                assert_se(routes[1].dst_prefixlen == 24);
+
+                assert_se(routes[2].dst_addr.s_addr == inet_addr("0.0.0.0"));
+                assert_se(routes[2].gw_addr.s_addr == inet_addr("10.0.1.1"));
+                assert_se(routes[2].dst_prefixlen == 0);
+        }
+
+        {
+                /* error in second word */
+                _cleanup_free_ struct sd_dhcp_route *routes = NULL;
+                const char *routes_string = "192.168.0.0/16,192.168.0.1 10.1.2.0#24,10.1.2.1 0.0.0.0/0,10.0.1.1";
+
+                assert_se(deserialize_dhcp_routes(&routes, &size, &allocated, routes_string) >= 0);
+
+                assert_se(size == 2);
+                assert_se(routes[0].dst_addr.s_addr == inet_addr("192.168.0.0"));
+                assert_se(routes[0].gw_addr.s_addr == inet_addr("192.168.0.1"));
+                assert_se(routes[0].dst_prefixlen == 16);
+
+                assert_se(routes[2].dst_addr.s_addr == inet_addr("0.0.0.0"));
+                assert_se(routes[2].gw_addr.s_addr == inet_addr("10.0.1.1"));
+                assert_se(routes[2].dst_prefixlen == 0);
+        }
+
+        {
+                /* error in every word */
+                _cleanup_free_ struct sd_dhcp_route *routes = NULL;
+                const char *routes_string = "192.168.0.0/55,192.168.0.1 10.1.2.0#24,10.1.2.1 0.0.0.0/0,10.0.1.X";
+
+                assert_se(deserialize_dhcp_routes(&routes, &size, &allocated, routes_string) >= 0);
+                assert_se(size == 0);
+        }
+}
+
 static void test_load_config(Manager *manager) {
 /*  TODO: should_reload, is false if the config dirs do not exist, so
  *        so we can't do this test here, move it to a test for paths_check_timestamps
@@ -125,6 +183,7 @@ int main(void) {
         struct udev_device *loopback;
 
         test_deserialize_in_addr();
+        test_deserialize_dhcp_routes();
         test_address_equality();
 
         assert_se(manager_new(&manager) >= 0);