dhcp: set request_broadcast for devices that set udev ID_NET_DHCP_BROADCASTth/dhcp-request-broadcast

For infiniband, request_broadcast is automatically (and always) enabled.
Otherwise, we usually don't enable it, and (unlike systemd-networkd),
there is currently no configuration option to enable it.

Still honor the new udev property that can indicate to enable the flag
per device.

See-also: https://github.com/systemd/systemd/pull/ ### 19346

6 files changed, 58 insertions, 26 deletions

diff --git a/src/core/devices/nm-device.c b/src/core/devices/nm-device.c
index a5714f1f74..bfc3f55a1e 100644
--- a/src/core/devices/nm-device.c
+++ b/src/core/devices/nm-device.c
@@ -9447,6 +9447,8 @@ dhcp4_start(NMDevice *self)
     GError *               error = NULL;
     const NMPlatformLink * pllink;
     const char *const *    reject_servers;
+    gboolean               request_broadcast;
+    const char *           str;
 
     connection = nm_device_get_applied_connection(self);
     g_return_val_if_fail(connection, FALSE);
@@ -9460,10 +9462,22 @@ dhcp4_start(NMDevice *self)
     nm_dbus_object_clear_and_unexport(&priv->dhcp_data_4.config);
     priv->dhcp_data_4.config = nm_dhcp_config_new(AF_INET);
 
+    request_broadcast = FALSE;
+
     pllink = nm_platform_link_get(nm_device_get_platform(self), nm_device_get_ip_ifindex(self));
     if (pllink) {
         hwaddr       = nmp_link_address_get_as_bytes(&pllink->l_address);
         bcast_hwaddr = nmp_link_address_get_as_bytes(&pllink->l_broadcast);
+
+        str = nmp_object_link_udev_device_get_property_value(NMP_OBJECT_UP_CAST(pllink),
+                                                             "ID_NET_DHCP_BROADCAST");
+        if (str && _nm_utils_ascii_str_to_bool(str, FALSE)) {
+            /* Use the device property ID_NET_DHCP_BROADCAST setting, which may be set for interfaces
+             * requiring that the DHCPOFFER message is being broadcast because they can't handle unicast
+             * messages while not fully configured.
+             */
+            request_broadcast = TRUE;
+        }
     }
 
     client_id = _prop_get_ipv4_dhcp_client_id(self, connection, hwaddr);
@@ -9472,29 +9486,29 @@ dhcp4_start(NMDevice *self)
     reject_servers = nm_setting_ip_config_get_dhcp_reject_servers(s_ip4, NULL);
 
     g_warn_if_fail(priv->dhcp_data_4.client == NULL);
-    priv->dhcp_data_4.client =
-        nm_dhcp_manager_start_ip4(nm_dhcp_manager_get(),
-                                  nm_netns_get_multi_idx(nm_device_get_netns(self)),
-                                  nm_device_get_ip_iface(self),
-                                  nm_device_get_ip_ifindex(self),
-                                  hwaddr,
-                                  bcast_hwaddr,
-                                  nm_connection_get_uuid(connection),
-                                  nm_device_get_route_table(self, AF_INET),
-                                  nm_device_get_route_metric(self, AF_INET),
-                                  NM_DHCP_CLIENT_FLAGS_NONE,
-                                  nm_setting_ip_config_get_dhcp_send_hostname(s_ip4),
-                                  nm_setting_ip_config_get_dhcp_hostname(s_ip4),
-                                  nm_setting_ip4_config_get_dhcp_fqdn(NM_SETTING_IP4_CONFIG(s_ip4)),
-                                  _prop_get_ipvx_dhcp_hostname_flags(self, AF_INET),
-                                  _prop_get_connection_mud_url(self, s_con, &mud_url_free),
-                                  client_id,
-                                  _prop_get_ipvx_dhcp_timeout(self, AF_INET),
-                                  priv->dhcp_anycast_address,
-                                  NULL,
-                                  vendor_class_identifier,
-                                  reject_servers,
-                                  &error);
+    priv->dhcp_data_4.client = nm_dhcp_manager_start_ip4(
+        nm_dhcp_manager_get(),
+        nm_netns_get_multi_idx(nm_device_get_netns(self)),
+        nm_device_get_ip_iface(self),
+        nm_device_get_ip_ifindex(self),
+        hwaddr,
+        bcast_hwaddr,
+        nm_connection_get_uuid(connection),
+        nm_device_get_route_table(self, AF_INET),
+        nm_device_get_route_metric(self, AF_INET),
+        request_broadcast ? NM_DHCP_CLIENT_FLAGS_REQUEST_BROADCAST : NM_DHCP_CLIENT_FLAGS_NONE,
+        nm_setting_ip_config_get_dhcp_send_hostname(s_ip4),
+        nm_setting_ip_config_get_dhcp_hostname(s_ip4),
+        nm_setting_ip4_config_get_dhcp_fqdn(NM_SETTING_IP4_CONFIG(s_ip4)),
+        _prop_get_ipvx_dhcp_hostname_flags(self, AF_INET),
+        _prop_get_connection_mud_url(self, s_con, &mud_url_free),
+        client_id,
+        _prop_get_ipvx_dhcp_timeout(self, AF_INET),
+        priv->dhcp_anycast_address,
+        NULL,
+        vendor_class_identifier,
+        reject_servers,
+        &error);
     if (!priv->dhcp_data_4.client) {
         _LOGW(LOGD_DHCP4, "failure to start DHCP: %s", error->message);
         g_clear_error(&error);
diff --git a/src/core/dhcp/nm-dhcp-client.c b/src/core/dhcp/nm-dhcp-client.c
index ab0ce4f9b6..0dc21be630 100644
--- a/src/core/dhcp/nm-dhcp-client.c
+++ b/src/core/dhcp/nm-dhcp-client.c
@@ -1152,8 +1152,10 @@ constructed(GObject *object)
      * for that. */
     if (NM_IS_IPv4(priv->addr_family))
         nm_assert(!NM_FLAGS_ANY(priv->client_flags, NM_DHCP_CLIENT_FLAGS_INFO_ONLY));
-    else
+    else {
         nm_assert(NM_FLAGS_HAS(priv->client_flags, NM_DHCP_CLIENT_FLAGS_USE_FQDN));
+        nm_assert(!NM_FLAGS_ANY(priv->client_flags, NM_DHCP_CLIENT_FLAGS_REQUEST_BROADCAST));
+    }
 
     G_OBJECT_CLASS(nm_dhcp_client_parent_class)->constructed(object);
 }
diff --git a/src/core/dhcp/nm-dhcp-client.h b/src/core/dhcp/nm-dhcp-client.h
index 4fc9f1e7c8..e61e01de3b 100644
--- a/src/core/dhcp/nm-dhcp-client.h
+++ b/src/core/dhcp/nm-dhcp-client.h
@@ -71,8 +71,9 @@ typedef struct {
 typedef enum _nm_packed {
     NM_DHCP_CLIENT_FLAGS_NONE = 0,
 
-    NM_DHCP_CLIENT_FLAGS_INFO_ONLY = (1LL << 0),
-    NM_DHCP_CLIENT_FLAGS_USE_FQDN  = (1LL << 1),
+    NM_DHCP_CLIENT_FLAGS_INFO_ONLY         = (1LL << 0),
+    NM_DHCP_CLIENT_FLAGS_USE_FQDN          = (1LL << 1),
+    NM_DHCP_CLIENT_FLAGS_REQUEST_BROADCAST = (1LL << 2),
 
     _NM_DHCP_CLIENT_FLAGS_LAST,
     NM_DHCP_CLIENT_FLAGS_ALL = ((_NM_DHCP_CLIENT_FLAGS_LAST - 1) << 1) - 1,
diff --git a/src/core/dhcp/nm-dhcp-dhclient.c b/src/core/dhcp/nm-dhcp-dhclient.c
index 199f0ad3bc..06a8c938cb 100644
--- a/src/core/dhcp/nm-dhcp-dhclient.c
+++ b/src/core/dhcp/nm-dhcp-dhclient.c
@@ -435,6 +435,12 @@ dhclient_start(NMDhcpClient *client,
     if (release)
         g_ptr_array_add(argv, (gpointer) "-r");
 
+    if (!release
+        && NM_FLAGS_HAS(nm_dhcp_client_get_client_flags(NM_DHCP_CLIENT(self)),
+                        NM_DHCP_CLIENT_FLAGS_REQUEST_BROADCAST)) {
+        g_ptr_array_add(argv, (gpointer) "-B");
+    }
+
     if (addr_family == AF_INET6) {
         g_ptr_array_add(argv, (gpointer) "-6");
 
diff --git a/src/core/dhcp/nm-dhcp-nettools.c b/src/core/dhcp/nm-dhcp-nettools.c
index 7c76f52a05..c1a26eca62 100644
--- a/src/core/dhcp/nm-dhcp-nettools.c
+++ b/src/core/dhcp/nm-dhcp-nettools.c
@@ -938,6 +938,10 @@ nettools_create(NMDhcpNettools *self, const char *dhcp_anycast_addr, GError **er
     n_dhcp4_client_config_set_transport(config, transport);
     n_dhcp4_client_config_set_mac(config, hwaddr_arr, hwaddr_len);
     n_dhcp4_client_config_set_broadcast_mac(config, bcast_hwaddr_arr, bcast_hwaddr_len);
+    n_dhcp4_client_config_set_request_broadcast(
+        config,
+        NM_FLAGS_HAS(nm_dhcp_client_get_client_flags(NM_DHCP_CLIENT(self)),
+                     NM_DHCP_CLIENT_FLAGS_REQUEST_BROADCAST));
     r = n_dhcp4_client_config_set_client_id(config,
                                             client_id_arr,
                                             NM_MIN(client_id_len, 1 + _NM_SD_MAX_CLIENT_ID_LEN));
diff --git a/src/core/dhcp/nm-dhcp-systemd.c b/src/core/dhcp/nm-dhcp-systemd.c
index 509607a943..5b06c65dba 100644
--- a/src/core/dhcp/nm-dhcp-systemd.c
+++ b/src/core/dhcp/nm-dhcp-systemd.c
@@ -632,6 +632,11 @@ ip4_start(NMDhcpClient *client,
             sd_dhcp_lease_get_address(lease, &last_addr);
     }
 
+    r = sd_dhcp_client_set_request_broadcast(sd_client,
+                                             NM_FLAGS_HAS(nm_dhcp_client_get_client_flags(client),
+                                                          NM_DHCP_CLIENT_FLAGS_REQUEST_BROADCAST));
+    nm_assert(r >= 0);
+
     if (last_addr.s_addr) {
         r = sd_dhcp_client_set_request_address(sd_client, &last_addr);
         if (r < 0) {