northd, controller: Add support for DHCPv6 FQDN option

Add support for FQDN option (39), if specified the server can overwrite FQDN for the client. It behaves similarly to DHCP hostname option (12). Reported-at: https://bugzilla.redhat.com/2211890 Signed-off-by: Ales Musil <amusil@redhat.com> Acked-by: Mark Michelson <mmichels@redhat.com> Signed-off-by: Mark Michelson <mmichels@redhat.com>
ovn-org · Jun 12, 2023 · b3ae86a · b3ae86a
1 parent 38644f0
commit b3ae86a
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Showing 11 changed files with 181 additions and 113 deletions.
diff --git a/NEWS b/NEWS
@@ -3,6 +3,8 @@ Post v23.06.0
   - Added FDB aging mechanism, that is disabled by default.
     It can be enabled per logical switch with other_config
     "fdb_age_threshold".
+  - Add DHCPv6 "fqdn" (39) option, that works similarly to
+    DHCPv4 "hostname" (12) option.
 
 OVN v23.06.0 - 01 Jun 2023
 --------------------------

diff --git a/controller/pinctrl.c b/controller/pinctrl.c
@@ -2289,7 +2289,7 @@ pinctrl_handle_put_dhcp_opts(
 static bool
 compose_out_dhcpv6_opts(struct ofpbuf *userdata,
                         struct ofpbuf *out_dhcpv6_opts,
-                        ovs_be32 iaid, bool ipxe_req)
+                        ovs_be32 iaid, bool ipxe_req, uint8_t fqdn_flags)
 {
     while (userdata->size) {
         struct dhcpv6_opt_header *userdata_opt = ofpbuf_try_pull(
@@ -2413,6 +2413,24 @@ compose_out_dhcpv6_opts(struct ofpbuf *userdata,
             break;
         }
 
+        case DHCPV6_OPT_FQDN_CODE: {
+            if (fqdn_flags != DHCPV6_FQDN_FLAGS_UNDEFINED) {
+                struct dhcpv6_opt_header *header =
+                        ofpbuf_put_zeros(out_dhcpv6_opts, sizeof *header);
+                header->code = htons(DHCPV6_OPT_FQDN_CODE);
+                header->len = htons(size + 1);
+                uint8_t *flags = ofpbuf_put_zeros(out_dhcpv6_opts, 1);
+                /* Always set N to 1, if client requested S inform him that it
+                 * was overwritten by the server. */
+                *flags |= DHCPV6_FQDN_FLAGS_N;
+                if (fqdn_flags & DHCPV6_FQDN_FLAGS_S) {
+                    *flags |= DHCPV6_FQDN_FLAGS_O;
+                }
+                ofpbuf_put(out_dhcpv6_opts, userdata_opt_data, size);
+            }
+            break;
+        }
+
         default:
             return false;
         }
@@ -2501,6 +2519,7 @@ pinctrl_handle_put_dhcpv6_opts(
     size_t l4_len = dp_packet_l4_size(pkt_in);
     uint8_t *end = (uint8_t *)in_udp + MIN(udp_len, l4_len);
     bool ipxe_req = false;
+    uint8_t fqdn_flags = DHCPV6_FQDN_FLAGS_UNDEFINED;
     while (in_dhcpv6_data < end) {
         struct dhcpv6_opt_header const *in_opt =
              (struct dhcpv6_opt_header *)in_dhcpv6_data;
@@ -2525,6 +2544,10 @@ pinctrl_handle_put_dhcpv6_opts(
             break;
         }
 
+        case DHCPV6_OPT_FQDN_CODE:
+            fqdn_flags = *(in_dhcpv6_data + sizeof *in_opt);
+            break;
+
         default:
             break;
         }
@@ -2548,7 +2571,7 @@ pinctrl_handle_put_dhcpv6_opts(
         OFPBUF_STUB_INITIALIZER(out_ofpacts_dhcpv6_opts_stub);
 
     if (!compose_out_dhcpv6_opts(userdata, &out_dhcpv6_opts,
-                                 iaid, ipxe_req)) {
+                                 iaid, ipxe_req, fqdn_flags)) {
         VLOG_WARN_RL(&rl, "Invalid userdata");
         goto exit;
     }
@@ -2763,48 +2786,16 @@ dns_build_ptr_answer(
     struct ofpbuf *dns_answer, const uint8_t *in_queryname,
     uint16_t query_length, const char *answer_data)
 {
-    char *encoded_answer;
-    uint16_t encoded_answer_length;
-
     dns_build_base_answer(dns_answer, in_queryname, query_length,
                           DNS_QUERY_TYPE_PTR);
 
-    /* Initialize string 2 chars longer than real answer:
-     * first label length and terminating zero-length label.
-     * If the answer_data is - vm1tst.ovn.org, it will be encoded as
-     *  - 0010 (Total length which is 16)
-     *  - 06766d31747374 (vm1tst)
-     *  - 036f766e (ovn)
-     *  - 036f7267 (org
-     *  - 00 (zero length field) */
-    encoded_answer_length = strlen(answer_data) + 2;
-    encoded_answer = (char *)xzalloc(encoded_answer_length);
-
-    put_be16(dns_answer, htons(encoded_answer_length));
-    uint8_t label_len_index = 0;
-    uint16_t label_len = 0;
-    char *encoded_answer_ptr = (char *)encoded_answer + 1;
-    while (*answer_data) {
-        if (*answer_data == '.') {
-            /* Label has ended.  Update the length of the label. */
-            encoded_answer[label_len_index] = label_len;
-            label_len_index += (label_len + 1);
-            label_len = 0; /* Init to 0 for the next label. */
-        } else {
-            *encoded_answer_ptr =  *answer_data;
-            label_len++;
-        }
-        encoded_answer_ptr++;
-        answer_data++;
-    }
+    size_t encoded_len = 0;
+    char *encoded = encode_fqdn_string(answer_data, &encoded_len);
 
-    /* This is required for the last label if it doesn't end with '.' */
-    if (label_len) {
-        encoded_answer[label_len_index] = label_len;
-    }
+    put_be16(dns_answer, htons(encoded_len));
+    ofpbuf_put(dns_answer, encoded, encoded_len);
 
-    ofpbuf_put(dns_answer, encoded_answer, encoded_answer_length);
-    free(encoded_answer);
+    free(encoded);
 }
 
 /* Called with in the pinctrl_handler thread context. */

diff --git a/lib/actions.c b/lib/actions.c
@@ -2470,7 +2470,8 @@ parse_gen_opt(struct action_context *ctx, struct ovnact_gen_option *o,
     }
 
     if (!strcmp(o->option->type, "str") ||
-        !strcmp(o->option->type, "domains")) {
+        !strcmp(o->option->type, "domains") ||
+        !strcmp(o->option->type, "domain")) {
         if (o->value.type != EXPR_C_STRING) {
             lexer_error(ctx->lexer, "%s option %s requires string value.",
                         opts_type, o->option->name);
@@ -2903,6 +2904,12 @@ encode_put_dhcpv6_option(const struct ovnact_gen_option *o,
         size = strlen(c->string);
         opt->len = htons(size);
         ofpbuf_put(ofpacts, c->string, size);
+    } else if (!strcmp(o->option->type, "domain")) {
+        char *encoded = encode_fqdn_string(c->string, &size);
+        opt->len = htons(size);
+        ofpbuf_put(ofpacts, encoded, size);
+
+        free(encoded);
     }
 }
 

diff --git a/lib/ovn-l7.h b/lib/ovn-l7.h
@@ -270,6 +270,7 @@ BUILD_ASSERT_DECL(DHCP_OPT_HEADER_LEN == sizeof(struct dhcp_opt_header));
 #define DHCPV6_OPT_DOMAIN_SEARCH_CODE    24
 #define DHCPV6_OPT_IA_PD                 25
 #define DHCPV6_OPT_IA_PREFIX             26
+#define DHCPV6_OPT_FQDN_CODE             39
 #define DHCPV6_OPT_BOOT_FILE_URL         59
 #define DHCPV6_OPT_BOOT_FILE_URL_ALT    254
 
@@ -291,6 +292,15 @@ BUILD_ASSERT_DECL(DHCP_OPT_HEADER_LEN == sizeof(struct dhcp_opt_header));
 #define DHCPV6_OPT_BOOTFILE_NAME_ALT \
     DHCP_OPTION("bootfile_name_alt", DHCPV6_OPT_BOOT_FILE_URL_ALT, "str")
 
+#define DHCPV6_OPT_FQDN \
+    DHCP_OPTION("fqdn", DHCPV6_OPT_FQDN_CODE, "domain")
+
+/* DHCPv6 FQDN flags. RFC 4704 */
+#define DHCPV6_FQDN_FLAGS_UNDEFINED 0xff
+#define DHCPV6_FQDN_FLAGS_S 1 << 0
+#define DHCPV6_FQDN_FLAGS_O 1 << 1
+#define DHCPV6_FQDN_FLAGS_N 1 << 2
+
 OVS_PACKED(
 struct dhcpv6_opt_header {
     ovs_be16 code;

diff --git a/lib/ovn-util.c b/lib/ovn-util.c
@@ -1141,3 +1141,30 @@ void flow_collector_ids_clear(struct flow_collector_ids *ids)
     flow_collector_ids_destroy(ids);
     flow_collector_ids_init(ids);
 }
+
+char *
+encode_fqdn_string(const char *fqdn, size_t *len)
+{
+
+    size_t domain_len = strlen(fqdn);
+    *len = domain_len + 2;
+    char *encoded = xzalloc(*len);
+
+    int8_t label_len = 0;
+    for (size_t i = 0; i < domain_len; i++) {
+        if (fqdn[i] == '.') {
+            encoded[i - label_len] = label_len;
+            label_len = 0;
+        } else {
+            encoded[i + 1] = fqdn[i];
+            label_len++;
+        }
+    }
+
+    /* This is required for the last label if it doesn't end with '.' */
+    if (label_len) {
+        encoded[domain_len - label_len] = label_len;
+    }
+
+    return encoded;
+}
diff --git a/lib/ovn-util.h b/lib/ovn-util.h
@@ -404,4 +404,9 @@ bool flow_collector_ids_lookup(const struct flow_collector_ids *, uint32_t);
 void flow_collector_ids_destroy(struct flow_collector_ids *);
 void flow_collector_ids_clear(struct flow_collector_ids *);
 
+/* The DNS format is 2 bytes longer than the "domain".
+ * It replaces every '.' with len of the next name.
+ * The returned pointer has to be freed by caller. */
+char *encode_fqdn_string(const char *fqdn, size_t *len);
+
 #endif /* OVN_UTIL_H */
diff --git a/northd/ovn-northd.c b/northd/ovn-northd.c
@@ -274,7 +274,8 @@ static struct gen_opts_map supported_dhcpv6_opts[] = {
     DHCPV6_OPT_DOMAIN_SEARCH,
     DHCPV6_OPT_DNS_SERVER,
     DHCPV6_OPT_BOOTFILE_NAME,
-    DHCPV6_OPT_BOOTFILE_NAME_ALT
+    DHCPV6_OPT_BOOTFILE_NAME_ALT,
+    DHCPV6_OPT_FQDN,
 };
 
 static bool

diff --git a/ovn-nb.xml b/ovn-nb.xml
@@ -4206,6 +4206,13 @@ or
             way. Default value for this option is false.
           </p>
         </column>
+
+        <column name="options" key="fqdn">
+          <p>
+            The DHCPv6 option code for this option is 39.
+            If set, indicates the DHCPv6 option "FQDN".
+          </p>
+        </column>
       </group>
     </group>
 

diff --git a/ovn-sb.ovsschema b/ovn-sb.ovsschema
@@ -1,7 +1,7 @@
 {
     "name": "OVN_Southbound",
-    "version": "20.27.3",
-    "cksum": "800899756 30521",
+    "version": "20.27.4",
+    "cksum": "3194181501 30531",
     "tables": {
         "SB_Global": {
             "columns": {
@@ -311,7 +311,7 @@
                 "type": {
                     "type": {"key": {
                         "type": "string",
-                        "enum": ["set", ["ipv6", "str", "mac"]]}}}},
+                        "enum": ["set", ["ipv6", "str", "mac", "domain"]]}}}},
             "isRoot": true},
         "Connection": {
             "columns": {