sd-dhcp-server: always send out ROUTER and SUBNET_MASK

For now we simply take these values from the server's address.

5 files changed, 33 insertions, 7 deletions

diff --git a/src/libsystemd-network/dhcp-server-internal.h b/src/libsystemd-network/dhcp-server-internal.h
index cdaa471b6..480da22c0 100644
--- a/src/libsystemd-network/dhcp-server-internal.h
+++ b/src/libsystemd-network/dhcp-server-internal.h
@@ -55,6 +55,7 @@ struct sd_dhcp_server {
 
         int index;
         be32_t address;
+        be32_t netmask;
         be32_t pool_start;
         size_t pool_size;
         size_t next_offer;
diff --git a/src/libsystemd-network/sd-dhcp-server.c b/src/libsystemd-network/sd-dhcp-server.c
index 50d9b7fcf..c224aa151 100644
--- a/src/libsystemd-network/sd-dhcp-server.c
+++ b/src/libsystemd-network/sd-dhcp-server.c
@@ -51,13 +51,16 @@ int sd_dhcp_server_set_lease_pool(sd_dhcp_server *server, struct in_addr *addres
         return 0;
 }
 
-int sd_dhcp_server_set_address(sd_dhcp_server *server, struct in_addr *address) {
+int sd_dhcp_server_set_address(sd_dhcp_server *server, struct in_addr *address, unsigned char prefixlen) {
         assert_return(server, -EINVAL);
         assert_return(address, -EINVAL);
         assert_return(address->s_addr, -EINVAL);
+        assert_return(prefixlen <= 32, -ERANGE);
         assert_return(server->address == htobe32(INADDR_ANY), -EBUSY);
+        assert_return(server->netmask == htobe32(INADDR_ANY), -EBUSY);
 
         server->address = address->s_addr;
+        server->netmask = htobe32(0xfffffffflu << (32 - prefixlen));
 
         return 0;
 }
@@ -150,6 +153,7 @@ int sd_dhcp_server_new(sd_dhcp_server **ret, int ifindex) {
         server->fd_raw = -1;
         server->fd = -1;
         server->address = htobe32(INADDR_ANY);
+        server->netmask = htobe32(INADDR_ANY);
         server->index = ifindex;
         server->leases_by_client_id = hashmap_new(client_id_hash_func, client_id_compare_func);
 
@@ -408,6 +412,16 @@ static int server_send_offer(sd_dhcp_server *server, DHCPRequest *req, be32_t ad
         if (r < 0)
                 return r;
 
+        r = dhcp_option_append(&packet->dhcp, req->max_optlen, &offset, 0,
+                               DHCP_OPTION_SUBNET_MASK, 4, &server->netmask);
+        if (r < 0)
+                return r;
+
+        r = dhcp_option_append(&packet->dhcp, req->max_optlen, &offset, 0,
+                               DHCP_OPTION_ROUTER, 4, &server->address);
+        if (r < 0)
+                return r;
+
         r = dhcp_server_send_packet(server, req, packet, DHCP_OFFER, offset);
         if (r < 0)
                 return r;
@@ -433,6 +447,16 @@ static int server_send_ack(sd_dhcp_server *server, DHCPRequest *req, be32_t addr
         if (r < 0)
                 return r;
 
+        r = dhcp_option_append(&packet->dhcp, req->max_optlen, &offset, 0,
+                               DHCP_OPTION_SUBNET_MASK, 4, &server->netmask);
+        if (r < 0)
+                return r;
+
+        r = dhcp_option_append(&packet->dhcp, req->max_optlen, &offset, 0,
+                               DHCP_OPTION_ROUTER, 4, &server->address);
+        if (r < 0)
+                return r;
+
         r = dhcp_server_send_packet(server, req, packet, DHCP_ACK, offset);
         if (r < 0)
                 return r;
diff --git a/src/libsystemd-network/test-dhcp-server.c b/src/libsystemd-network/test-dhcp-server.c
index a9bdb9ab8..a94b62f8e 100644
--- a/src/libsystemd-network/test-dhcp-server.c
+++ b/src/libsystemd-network/test-dhcp-server.c
@@ -56,9 +56,10 @@ static int test_basic(sd_event *event) {
         assert_se(!sd_dhcp_server_unref(server));
 
         assert_se(sd_dhcp_server_start(server) == -EUNATCH);
-        assert_se(sd_dhcp_server_set_address(server, &address_any) == -EINVAL);
-        assert_se(sd_dhcp_server_set_address(server, &address_lo) >= 0);
-        assert_se(sd_dhcp_server_set_address(server, &address_lo) == -EBUSY);
+        assert_se(sd_dhcp_server_set_address(server, &address_any, 28) == -EINVAL);
+        assert_se(sd_dhcp_server_set_address(server, &address_any, 38) == -ERANGE);
+        assert_se(sd_dhcp_server_set_address(server, &address_lo, 8) >= 0);
+        assert_se(sd_dhcp_server_set_address(server, &address_lo, 8) == -EBUSY);
 
         assert_se(sd_dhcp_server_set_lease_pool(server, &address_any, 1) == -EINVAL);
         assert_se(sd_dhcp_server_set_lease_pool(server, &address_lo, 0) == -EINVAL);
@@ -120,7 +121,7 @@ static void test_message_handler(void) {
         };
 
         assert_se(sd_dhcp_server_new(&server, 1) >= 0);
-        assert_se(sd_dhcp_server_set_address(server, &address_lo) >= 0);
+        assert_se(sd_dhcp_server_set_address(server, &address_lo, 8) >= 0);
         assert_se(sd_dhcp_server_attach_event(server, NULL, 0) >= 0);
         assert_se(sd_dhcp_server_start(server) >= 0);
 
diff --git a/src/network/networkd-link.c b/src/network/networkd-link.c
index e674b3b12..accb42bf3 100644
--- a/src/network/networkd-link.c
+++ b/src/network/networkd-link.c
@@ -311,7 +311,7 @@ static int link_enter_configured(Link *link) {
 
                 log_debug_link(link, "offering DHCPv4 leases");
 
-                r = sd_dhcp_server_set_address(link->dhcp_server, &address->in_addr.in);
+                r = sd_dhcp_server_set_address(link->dhcp_server, &address->in_addr.in, address->prefixlen);
                 if (r < 0)
                         return r;
 
diff --git a/src/systemd/sd-dhcp-server.h b/src/systemd/sd-dhcp-server.h
index a4f7c85d6..9af3b6532 100644
--- a/src/systemd/sd-dhcp-server.h
+++ b/src/systemd/sd-dhcp-server.h
@@ -44,7 +44,7 @@ bool sd_dhcp_server_is_running(sd_dhcp_server *server);
 int sd_dhcp_server_start(sd_dhcp_server *server);
 int sd_dhcp_server_stop(sd_dhcp_server *server);
 
-int sd_dhcp_server_set_address(sd_dhcp_server *server, struct in_addr *address);
+int sd_dhcp_server_set_address(sd_dhcp_server *server, struct in_addr *address, unsigned char prefixlen);
 int sd_dhcp_server_set_lease_pool(sd_dhcp_server *server, struct in_addr *start, size_t size);
 
 int sd_dhcp_server_forcerenew(sd_dhcp_server *server);