initrd: fix parsing of ip= arguments with empty first token

The parser checks if the first token of an ip= argument is an IP
address to determine which of the two possible syntaxes is used:

 ip=<interface>:{dhcp|on|any|dhcp6|auto6}[:[<mtu>][:<macaddr>]]
 ip=<client-IP>:[<peer>]:<gateway-IP>:<netmask>:<client_hostname>:<interface>:{none|off|dhcp|on|any|dhcp6|auto6|ibft}[:[<mtu>][:<macaddr>]]

This works as long as the first token is not empty, which - according
to the dracut.cmdline man page - seems to be guaranteed.

However, the network-legacy dracut plugin accepts an empty interface
or client IP. Also, if a user needs DHCP and wants to specify a
hostname, the only possible syntax is:

 ip=::::<hostname>::dhcp

Change the parser to check the second token instead, similarly to what
the network-legacy module does [1].

[1] https://github.com/dracutdevs/dracut/blob/050/modules.d/40network/net-lib.sh#L490

https://bugzilla.redhat.com/show_bug.cgi?id=1900260
https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/merge_requests/693

src/initrd/nmi-cmdline-reader.c

@@ -390,6 +390,7 @@ reader_parse_ip(Reader *reader, const char *sysfs_dir, char *argument)
     NMSettingIPConfig *s_ip4 = NULL, *s_ip6 = NULL;
     gs_unref_hashtable GHashTable *ibft = NULL;
     const char *                   tmp;
+    const char *                   tmp2;
     const char *                   kind             = NULL;
     const char *                   client_ip        = NULL;
     const char *                   peer             = NULL;
@@ -418,17 +419,37 @@ reader_parse_ip(Reader *reader, const char *sysfs_dir, char *argument)
         /* ip={dhcp|on|any|dhcp6|auto6|ibft} */
         kind = tmp;
     } else {
-        client_ip_family = get_ip_address_family(tmp, TRUE);
+        tmp2 = get_word(&argument, ':');
-        if (client_ip_family != AF_UNSPEC) {
+        if (NM_IN_STRSET(tmp2,
-            /* <client-IP>:[<peer>]:<gateway-IP>:<netmask>:<client_hostname>: */
+                         "none",
+                         "off",
+                         "dhcp",
+                         "on"
+                         "any",
+                         "dhcp6",
+                         "auto",
+                         "auto6",
+                         "ibft")) {
+            /* <ifname>:{none|off|dhcp|on|any|dhcp6|auto|auto6|ibft} */
+            iface_spec = tmp;
+            kind       = tmp2;
+        } else {
+            /* <client-IP>:[<peer>]:<gateway-IP>:<netmask>:<client_hostname>:<kind> */
             client_ip = tmp;
-            peer            = get_word(&argument, ':');
+            if (client_ip) {
+                client_ip_family = get_ip_address_family(client_ip, TRUE);
+                if (client_ip_family == AF_UNSPEC) {
+                    _LOGW(LOGD_CORE, "Invalid IP address '%s'.", client_ip);
+                    return;
+                }
+            }
+
+            peer            = tmp2;
             gateway_ip      = get_word(&argument, ':');
             netmask         = get_word(&argument, ':');
             client_hostname = get_word(&argument, ':');
             iface_spec      = get_word(&argument, ':');
-        } else {
+            kind            = get_word(&argument, ':');
-            iface_spec = tmp;
         }
 
         if (client_hostname && !nm_sd_hostname_is_valid(client_hostname, FALSE))
@@ -439,10 +460,6 @@ reader_parse_ip(Reader *reader, const char *sysfs_dir, char *argument)
             reader->hostname = g_strdup(client_hostname);
         }
 
-        /* <ifname>:{none|off|dhcp|on|any|dhcp6|auto6|ibft} */
-
-        kind = get_word(&argument, ':');
-
         tmp                = get_word(&argument, ':');
         dns_addr_family[0] = get_ip_address_family(tmp, FALSE);
         if (dns_addr_family[0] != AF_UNSPEC) {

src/initrd/tests/test-cmdline-reader.c

@@ -79,6 +79,116 @@ test_auto(void)
     g_assert(!nm_setting_ip_config_get_gateway(s_ip6));
 }
 
+static void
+test_dhcp_with_hostname(void)
+{
+    gs_unref_hashtable GHashTable *connections = NULL;
+    const char *const *            ARGV        = NM_MAKE_STRV("ip=::::host1::dhcp");
+    NMConnection *                 connection;
+    NMSettingConnection *          s_con;
+    NMSettingWired *               s_wired;
+    NMSettingIPConfig *            s_ip4;
+    NMSettingIPConfig *            s_ip6;
+    gs_free char *                 hostname = NULL;
+
+    connections = nmi_cmdline_reader_parse(TEST_INITRD_DIR "/sysfs", ARGV, &hostname);
+    g_assert(connections);
+    g_assert_cmpint(g_hash_table_size(connections), ==, 1);
+    g_assert_cmpstr(hostname, ==, "host1");
+
+    connection = g_hash_table_lookup(connections, "default_connection");
+    g_assert(connection);
+    nmtst_assert_connection_verifies_without_normalization(connection);
+
+    g_assert(!nm_connection_get_setting_vlan(connection));
+
+    s_con = nm_connection_get_setting_connection(connection);
+    g_assert(s_con);
+    g_assert_cmpstr(nm_setting_connection_get_connection_type(s_con),
+                    ==,
+                    NM_SETTING_WIRED_SETTING_NAME);
+    g_assert_cmpstr(nm_setting_connection_get_id(s_con), ==, "Wired Connection");
+    g_assert_cmpint(nm_setting_connection_get_timestamp(s_con), ==, 0);
+    g_assert_cmpint(nm_setting_connection_get_multi_connect(s_con),
+                    ==,
+                    NM_CONNECTION_MULTI_CONNECT_MULTIPLE);
+    g_assert_cmpint(nm_setting_connection_get_wait_device_timeout(s_con), ==, -1);
+
+    g_assert(nm_setting_connection_get_autoconnect(s_con));
+
+    s_wired = nm_connection_get_setting_wired(connection);
+    g_assert(s_wired);
+    g_assert(!nm_setting_wired_get_mac_address(s_wired));
+    g_assert_cmpint(nm_setting_wired_get_mtu(s_wired), ==, 0);
+
+    s_ip4 = nm_connection_get_setting_ip4_config(connection);
+    g_assert(s_ip4);
+    g_assert_cmpstr(nm_setting_ip_config_get_method(s_ip4), ==, NM_SETTING_IP4_CONFIG_METHOD_AUTO);
+
+    s_ip6 = nm_connection_get_setting_ip6_config(connection);
+    g_assert(s_ip6);
+    g_assert_cmpstr(nm_setting_ip_config_get_method(s_ip6), ==, NM_SETTING_IP6_CONFIG_METHOD_AUTO);
+}
+
+static void
+test_dhcp_with_mtu(void)
+{
+    const char *const *ARGV0  = NM_MAKE_STRV("ip=:dhcp:1499");
+    const char *const *ARGV1  = NM_MAKE_STRV("ip=::::::dhcp:1499");
+    const char *const *ARGV[] = {ARGV0, ARGV1};
+    guint              i;
+
+    for (i = 0; i < G_N_ELEMENTS(ARGV); i++) {
+        gs_unref_hashtable GHashTable *connections = NULL;
+        NMConnection *                 connection;
+        NMSettingConnection *          s_con;
+        NMSettingWired *               s_wired;
+        NMSettingIPConfig *            s_ip4;
+        NMSettingIPConfig *            s_ip6;
+        gs_free char *                 hostname = NULL;
+
+        connections = nmi_cmdline_reader_parse(TEST_INITRD_DIR "/sysfs", ARGV[i], &hostname);
+        g_assert(connections);
+        g_assert_cmpint(g_hash_table_size(connections), ==, 1);
+        g_assert_cmpstr(hostname, ==, NULL);
+
+        connection = g_hash_table_lookup(connections, "default_connection");
+        g_assert(connection);
+        nmtst_assert_connection_verifies_without_normalization(connection);
+
+        s_con = nm_connection_get_setting_connection(connection);
+        g_assert(s_con);
+        g_assert_cmpstr(nm_setting_connection_get_connection_type(s_con),
+                        ==,
+                        NM_SETTING_WIRED_SETTING_NAME);
+        g_assert_cmpstr(nm_setting_connection_get_id(s_con), ==, "Wired Connection");
+        g_assert_cmpint(nm_setting_connection_get_timestamp(s_con), ==, 0);
+        g_assert_cmpint(nm_setting_connection_get_multi_connect(s_con),
+                        ==,
+                        NM_CONNECTION_MULTI_CONNECT_MULTIPLE);
+        g_assert_cmpint(nm_setting_connection_get_wait_device_timeout(s_con), ==, -1);
+
+        g_assert(nm_setting_connection_get_autoconnect(s_con));
+
+        s_wired = nm_connection_get_setting_wired(connection);
+        g_assert(s_wired);
+        g_assert(!nm_setting_wired_get_mac_address(s_wired));
+        g_assert_cmpint(nm_setting_wired_get_mtu(s_wired), ==, 1499);
+
+        s_ip4 = nm_connection_get_setting_ip4_config(connection);
+        g_assert(s_ip4);
+        g_assert_cmpstr(nm_setting_ip_config_get_method(s_ip4),
+                        ==,
+                        NM_SETTING_IP4_CONFIG_METHOD_AUTO);
+
+        s_ip6 = nm_connection_get_setting_ip6_config(connection);
+        g_assert(s_ip6);
+        g_assert_cmpstr(nm_setting_ip_config_get_method(s_ip6),
+                        ==,
+                        NM_SETTING_IP6_CONFIG_METHOD_AUTO);
+    }
+}
+
 static void
 test_if_auto_with_mtu(void)
 {
@@ -2071,6 +2181,8 @@ main(int argc, char **argv)
     nmtst_init_assert_logging(&argc, &argv, "INFO", "DEFAULT");
 
     g_test_add_func("/initrd/cmdline/auto", test_auto);
+    g_test_add_func("/initrd/cmdline/dhcp_with_hostname", test_dhcp_with_hostname);
+    g_test_add_func("/initrd/cmdline/dhcp_with_mtu", test_dhcp_with_mtu);
     g_test_add_func("/initrd/cmdline/if_auto_with_mtu", test_if_auto_with_mtu);
     g_test_add_func("/initrd/cmdline/if_dhcp6", test_if_dhcp6);
     g_test_add_func("/initrd/cmdline/if_auto_with_mtu_and_mac", test_if_auto_with_mtu_and_mac);