keymgr: ds command with no params prints all

fixing #516
when calling 'keymgr -c/-C/-d <path> <zone> ds', the DS records for all KSKs in the zone are generated

doc/man/keymgr.8in

@@ -95,9 +95,9 @@ Changes a timing argument of an existing key to new timestamp. \fIKey_spec\fP is
 key tag or a prefix of key ID; \fIarguments\fP are like for \fBgenerate\fP, but just
 timing\-related ones.
 .TP
-\fBds\fP \fIkey_spec\fP
+\fBds\fP [\fIkey_spec\fP]
 Generate DS record (all digest algorithms together) from specified key. \fIKey_spec\fP
-is like for \fBset\fP\&.
+is like for \fBset\fP, if unspecified, all KSKs are used.
 .TP
 \fBdelete\fP \fIkey_spec\fP
 Remove the specified key from zone. If the key was not shared, it is also deleted from keystore.

doc/man_keymgr.rst

@@ -72,9 +72,9 @@ Actions
   key tag or a prefix of key ID; *arguments* are like for **generate**, but just
   timing-related ones.
 
-**ds** *key_spec*
+**ds** [*key_spec*]
   Generate DS record (all digest algorithms together) from specified key. *Key_spec*
-  is like for **set**.
+  is like for **set**, if unspecified, all KSKs are used.
 
 **delete** *key_spec*
   Remove the specified key from zone. If the key was not shared, it is also deleted from keystore.

src/utils/keymgr/main.c

@@ -125,14 +125,17 @@ static int key_command(int argc, char *argv[])
 		ret = keymgr_list_keys(&kctx);
 	} else if (strcmp(argv[1], "ds") == 0) {
 		if (argc < 3) {
-			printf("Key is not specified\n");
-			ret = KNOT_EINVAL;
-			goto main_end;
-		}
-		knot_kasp_key_t *key2ds;
-		ret = keymgr_get_key(&kctx, argv[2], &key2ds);
-		if (ret == KNOT_EOK) {
-			ret = keymgr_generate_ds(zone_name, key2ds);
+			for (int i = 0; i < kctx.zone->num_keys && ret == KNOT_EOK; i++) {
+				if (dnssec_key_get_flags(kctx.zone->keys[i].key) == DNSKEY_FLAGS_KSK) {
+					ret = keymgr_generate_ds(zone_name, &kctx.zone->keys[i]);
+				}
+			}
+		} else {
+			knot_kasp_key_t *key2ds;
+			ret = keymgr_get_key(&kctx, argv[2], &key2ds);
+			if (ret == KNOT_EOK) {
+				ret = keymgr_generate_ds(zone_name, key2ds);
+			}
 		}
 	} else if (strcmp(argv[1], "share") == 0) {
 		knot_dname_t *other_zone = NULL;