network: nexthop: introduce Family= setting in [NextHop] section

This is an alias of `Gateway=0.0.0.0` or `Gateway=::`.

src/network/networkd-network-gperf.gperf

@@ -186,6 +186,7 @@ Route.TTLPropagate,                          config_parse_route_boolean,
 Route.MultiPathRoute,                        config_parse_multipath_route,                             0,                             0
 NextHop.Id,                                  config_parse_nexthop_id,                                  0,                             0
 NextHop.Gateway,                             config_parse_nexthop_gateway,                             0,                             0
+NextHop.Family,                              config_parse_nexthop_family,                              0,                             0
 DHCPv4.ClientIdentifier,                     config_parse_dhcp_client_identifier,                      0,                             offsetof(Network, dhcp_client_identifier)
 DHCPv4.UseDNS,                               config_parse_dhcp_use_dns,                                0,                             0
 DHCPv4.RoutesToDNS,                          config_parse_bool,                                        0,                             offsetof(Network, dhcp_routes_to_dns)

src/network/networkd-nexthop.c

@@ -538,3 +538,69 @@ int config_parse_nexthop_gateway(
         TAKE_PTR(n);
         return 0;
 }
+
+int config_parse_nexthop_family(
+                const char *unit,
+                const char *filename,
+                unsigned line,
+                const char *section,
+                unsigned section_line,
+                const char *lvalue,
+                int ltype,
+                const char *rvalue,
+                void *data,
+                void *userdata) {
+
+        _cleanup_(nexthop_free_or_set_invalidp) NextHop *n = NULL;
+        Network *network = userdata;
+        AddressFamily a;
+        int r;
+
+        assert(filename);
+        assert(section);
+        assert(lvalue);
+        assert(rvalue);
+        assert(data);
+
+        r = nexthop_new_static(network, filename, section_line, &n);
+        if (r < 0)
+                return log_oom();
+
+        if (isempty(rvalue) &&
+            in_addr_is_null(n->family, &n->gw) != 0) {
+                /* Accept an empty string only when Gateway= is null or not specified. */
+                n->family = AF_UNSPEC;
+                TAKE_PTR(n);
+                return 0;
+        }
+
+        a = nexthop_address_family_from_string(rvalue);
+        if (a < 0) {
+                log_syntax(unit, LOG_WARNING, filename, line, 0,
+                           "Invalid %s='%s', ignoring assignment: %m", lvalue, rvalue);
+                return 0;
+        }
+
+        if (in_addr_is_null(n->family, &n->gw) == 0 &&
+            ((a == ADDRESS_FAMILY_IPV4 && n->family == AF_INET6) ||
+             (a == ADDRESS_FAMILY_IPV6 && n->family == AF_INET))) {
+                log_syntax(unit, LOG_WARNING, filename, line, 0,
+                           "Specified family '%s' conflicts with the family of the previously specified Gateway=, "
+                           "ignoring assignment.", rvalue);
+                return 0;
+        }
+
+        switch(a) {
+        case ADDRESS_FAMILY_IPV4:
+                n->family = AF_INET;
+                break;
+        case ADDRESS_FAMILY_IPV6:
+                n->family = AF_INET6;
+                break;
+        default:
+                assert_not_reached("Invalid family.");
+        }
+
+        TAKE_PTR(n);
+        return 0;
+}

src/network/networkd-nexthop.h

@@ -39,3 +39,4 @@ int manager_rtnl_process_nexthop(sd_netlink *rtnl, sd_netlink_message *message,
 
 CONFIG_PARSER_PROTOTYPE(config_parse_nexthop_id);
 CONFIG_PARSER_PROTOTYPE(config_parse_nexthop_gateway);
+CONFIG_PARSER_PROTOTYPE(config_parse_nexthop_family);

src/network/networkd-util.c

@@ -21,6 +21,11 @@ static const char* const routing_policy_rule_address_family_table[_ADDRESS_FAMIL
         [ADDRESS_FAMILY_IPV6]          = "ipv6",
 };
 
+static const char* const nexthop_address_family_table[_ADDRESS_FAMILY_MAX] = {
+        [ADDRESS_FAMILY_IPV4]          = "ipv4",
+        [ADDRESS_FAMILY_IPV6]          = "ipv6",
+};
+
 static const char* const duplicate_address_detection_address_family_table[_ADDRESS_FAMILY_MAX] = {
         [ADDRESS_FAMILY_NO]            = "none",
         [ADDRESS_FAMILY_YES]           = "both",
@@ -55,6 +60,7 @@ AddressFamily link_local_address_family_from_string(const char *s) {
 }
 
 DEFINE_STRING_TABLE_LOOKUP(routing_policy_rule_address_family, AddressFamily);
+DEFINE_STRING_TABLE_LOOKUP(nexthop_address_family, AddressFamily);
 DEFINE_STRING_TABLE_LOOKUP(duplicate_address_detection_address_family, AddressFamily);
 DEFINE_CONFIG_PARSE_ENUM(config_parse_link_local_address_family, link_local_address_family,
                          AddressFamily, "Failed to parse option");

src/network/networkd-util.h

@@ -38,6 +38,9 @@ AddressFamily link_local_address_family_from_string(const char *s) _pure_;
 const char *routing_policy_rule_address_family_to_string(AddressFamily b) _const_;
 AddressFamily routing_policy_rule_address_family_from_string(const char *s) _pure_;
 
+const char *nexthop_address_family_to_string(AddressFamily b) _const_;
+AddressFamily nexthop_address_family_from_string(const char *s) _pure_;
+
 const char *duplicate_address_detection_address_family_to_string(AddressFamily b) _const_;
 AddressFamily duplicate_address_detection_address_family_from_string(const char *s) _pure_;
 

test/fuzz/fuzz-network-parser/directives.network

@@ -349,6 +349,7 @@ SendVendorOption=
 [NextHop]
 Id=
 Gateway=
+Family=
 [QDisc]
 Parent=
 Handle=