dhcp: allow FQDNs in ipv4.dhcp-hostname

If users wrote a FQDN in ipv4.dhcp-hostname presumably it's because
they really want to send the full value, not only the host part, so
let's send it as-is.

This obviously is a change in behavior, but only for users that have a
FQDN in ipv4.dhcp-hostname, where it's not clear if they really want the
domain to be stripped.

When the property is unset, we keep sending only the host part of the
system hostname to maintain backwards compatibility.

This commit aligns NM behavior to initscripts.

src/dhcp/nm-dhcp-dhclient-utils.c

@@ -95,24 +95,14 @@ grab_request_options (GPtrArray *store, const char* line)
 static void
 add_hostname4 (GString *str, const char *hostname, gboolean use_fqdn)
 {
-	char *plain_hostname, *dot;
-
 	if (hostname) {
 		if (use_fqdn) {
 			g_string_append_printf (str, FQDN_FORMAT "\n", hostname);
 			g_string_append (str,
 			                 "send fqdn.encoded on;\n"
 			                 "send fqdn.server-update on;\n");
-		} else {
+		} else
-			plain_hostname = g_strdup (hostname);
+			g_string_append_printf (str, HOSTNAME4_FORMAT "\n", hostname);
-			dot = strchr (plain_hostname, '.');
-			/* get rid of the domain */
-			if (dot)
-				*dot = '\0';
-
-			g_string_append_printf (str, HOSTNAME4_FORMAT "\n", plain_hostname);
-			g_free (plain_hostname);
-		}
 	}
 }
 

src/dhcp/nm-dhcp-dhcpcd.c

@@ -88,9 +88,8 @@ ip4_start (NMDhcpClient *client, const char *dhcp_anycast_addr, const char *last
 	GPtrArray *argv = NULL;
 	pid_t pid = -1;
 	GError *error = NULL;
-	char *pid_contents = NULL, *binary_name, *cmd_str, *dot;
+	char *pid_contents = NULL, *binary_name, *cmd_str;
 	const char *iface, *dhcpcd_path, *hostname;
-	gs_free char *prefix = NULL;
 
 	g_return_val_if_fail (priv->pid_file == NULL, FALSE);
 
@@ -146,14 +145,8 @@ ip4_start (NMDhcpClient *client, const char *dhcp_anycast_addr, const char *last
 			g_ptr_array_add (argv, (gpointer) "-F");
 			g_ptr_array_add (argv, (gpointer) "both");
 		} else {
-			prefix = strdup (hostname);
+			g_ptr_array_add (argv, (gpointer) "-h");
-			dot = strchr (prefix, '.');
+			g_ptr_array_add (argv, (gpointer) hostname);
-			/* get rid of the domain */
-			if (dot)
-				*dot = '\0';
-
-			g_ptr_array_add (argv, (gpointer) "-h");	/* Send hostname to DHCP server */
-			g_ptr_array_add (argv, (gpointer) prefix);
 		}
 	}
 

src/dhcp/nm-dhcp-manager.c

@@ -219,15 +219,6 @@ client_start (NMDhcpManager *self,
 	return client;
 }
 
-static const char *
-get_send_hostname (NMDhcpManager *self, const char *setting_hostname)
-{
-	NMDhcpManagerPrivate *priv = NM_DHCP_MANAGER_GET_PRIVATE (self);
-
-	/* Always prefer the explicit dhcp-send-hostname if given */
-	return setting_hostname ? setting_hostname : priv->default_hostname;
-}
-
 /* Caller owns a reference to the NMDhcpClient on return */
 NMDhcpClient *
 nm_dhcp_manager_start_ip4 (NMDhcpManager *self,
@@ -244,17 +235,36 @@ nm_dhcp_manager_start_ip4 (NMDhcpManager *self,
                            const char *dhcp_anycast_addr,
                            const char *last_ip_address)
 {
+	NMDhcpManagerPrivate *priv;
 	const char *hostname = NULL;
+	gs_free char *hostname_tmp = NULL;
 	gboolean use_fqdn = FALSE;
+	char *dot;
 
 	g_return_val_if_fail (NM_IS_DHCP_MANAGER (self), NULL);
+	priv = NM_DHCP_MANAGER_GET_PRIVATE (self);
 
 	if (send_hostname) {
+		/* Use, in order of preference:
+		 *  1. FQDN from configuration
+		 *  2. hostname from configuration
+		 *  3. system hostname (only host part)
+		 */
 		if (dhcp_fqdn) {
 			hostname = dhcp_fqdn;
 			use_fqdn = TRUE;
-		} else
+		} else if (dhcp_hostname)
-			hostname = get_send_hostname (self, dhcp_hostname);
+			hostname = dhcp_hostname;
+		else {
+			hostname = priv->default_hostname;
+			if (hostname) {
+				hostname_tmp = g_strdup (hostname);
+				dot = strchr (hostname_tmp, '.');
+				if (dot)
+					*dot = '\0';
+				hostname = hostname_tmp;
+			}
+		}
 	}
 
 	return client_start (self, iface, ifindex, hwaddr, uuid, priority, FALSE, NULL,
@@ -279,12 +289,16 @@ nm_dhcp_manager_start_ip6 (NMDhcpManager *self,
                            NMSettingIP6ConfigPrivacy privacy,
                            guint needed_prefixes)
 {
+	NMDhcpManagerPrivate *priv;
 	const char *hostname = NULL;
 
 	g_return_val_if_fail (NM_IS_DHCP_MANAGER (self), NULL);
+	priv = NM_DHCP_MANAGER_GET_PRIVATE (self);
 
-	if (send_hostname)
+	if (send_hostname) {
-		hostname = get_send_hostname (self, dhcp_hostname);
+		/* Always prefer the explicit dhcp-hostname if given */
+		hostname = dhcp_hostname ? dhcp_hostname : priv->default_hostname;
+	}
 	return client_start (self, iface, ifindex, hwaddr, uuid, priority, TRUE,
 	                     ll_addr, NULL, timeout, dhcp_anycast_addr, hostname, TRUE, info_only,
 	                     privacy, NULL, needed_prefixes);

src/dhcp/nm-dhcp-systemd.c

@@ -687,28 +687,14 @@ ip4_start (NMDhcpClient *client, const char *dhcp_anycast_addr, const char *last
 
 	hostname = nm_dhcp_client_get_hostname (client);
 	if (hostname) {
-		if (nm_dhcp_client_get_use_fqdn (client)) {
+		/* FIXME: sd-dhcp decides which hostname/FQDN option to send (12 or 81)
-			r = sd_dhcp_client_set_hostname (priv->client4, hostname);
+		 * only based on whether the hostname has a domain part or not. At the
-			if (r < 0) {
+		 * moment there is no way to force one or another.
-				_LOGW ("failed to set DHCP FQDN (%d)", r);
+		 */
-				goto error;
+		r = sd_dhcp_client_set_hostname (priv->client4, hostname);
-			}
+		if (r < 0) {
-		} else {
+			_LOGW ("failed to set DHCP hostname to '%s' (%d)", hostname, r);
-			char *prefix, *dot;
+			goto error;
-
-			prefix = strdup (hostname);
-			dot = strchr (prefix, '.');
-			/* get rid of the domain */
-			if (dot)
-				*dot = '\0';
-
-			r = sd_dhcp_client_set_hostname (priv->client4, prefix);
-			free (prefix);
-
-			if (r < 0) {
-				_LOGW ("failed to set DHCP hostname (%d)", r);
-				goto error;
-			}
 		}
 	}