make "max_restarts" a configurable value

MAX_RESTARTS is no longer hard-coded; ns_server_setmaxrestarts()
and dns_client_setmaxrestarts() can now be used to modify the
max-restarts value at runtime. in both cases, the default is 11.

(cherry picked from commit c5588babaf89f3e3ad2edccaada716e55c135dd3)
(cherry picked from commit bfbc6a6c840461a530077f2d5b02f9a53500f8ce)

diff --git a/bin/delv/delv.c b/bin/delv/delv.c
index ec330cd9ec64b144325532685a22ea8feab61f09..324b60af8046347593ea255360f4ca204a8708d4 100644 (file)
--- a/bin/delv/delv.c
+++ b/bin/delv/delv.c
@@ -85,6 +85,12 @@
 
 #define MAXNAME (DNS_NAME_MAXTEXT+1)
 
+/*
+ * Default maximum number of chained queries before we give up
+ * to prevent CNAME loops.
+ */
+#define MAX_RESTARTS 11
+
 /* Variables used internally by delv. */
 char *progname;
 static isc_mem_t *mctx = NULL;
@@ -1666,6 +1672,8 @@ main(int argc, char *argv[]) {
                goto cleanup;
        }
 
+       dns_client_setmaxrestarts(client, MAX_RESTARTS);
+
        /* Set the nameserver */
        if (server != NULL)
                addserver(client);

diff --git a/bin/named/query.c b/bin/named/query.c
index e5def824bf1005fd18a0d16176609bb14c695eaf..897beb7313ee3f0ca5eb0985037d66bfb66f110d 100644 (file)
--- a/bin/named/query.c
+++ b/bin/named/query.c
@@ -5999,8 +5999,6 @@ rpz_add_cname(ns_client_t *client, dns_rpz_st_t *st,
        return (ISC_R_SUCCESS);
 }
 
-#define MAX_RESTARTS 11
-
 #define QUERY_ERROR(r) \
 do { \
        eresult = r; \
@@ -9280,7 +9278,9 @@ query_find(ns_client_t *client, dns_fetchevent_t *event, dns_rdatatype_t qtype)
        /*
         * Restart the query?
         */
-       if (want_restart && client->query.restarts < MAX_RESTARTS) {
+       if (want_restart && client->query.restarts <
+           client->view->max_restarts)
+       {
                client->query.restarts++;
                goto restart;
        }

diff --git a/lib/dns/client.c b/lib/dns/client.c
index 9accdf7dd9163e895f0ec5e0c20eb5293c7b4849..0831044e11fd36b9c330cc21686f45af237debbd 100644 (file)
--- a/lib/dns/client.c
+++ b/lib/dns/client.c
@@ -63,8 +63,6 @@
 #define UCTX_MAGIC                     ISC_MAGIC('U', 'c', 't', 'x')
 #define UCTX_VALID(c)                  ISC_MAGIC_VALID(c, UCTX_MAGIC)
 
-#define MAX_RESTARTS 11
-
 #ifdef TUNE_LARGE
 #define RESOLVER_NTASKS 523
 #else
@@ -94,6 +92,7 @@ struct dns_client {
        unsigned int                    update_udpretries;
        unsigned int                    find_timeout;
        unsigned int                    find_udpretries;
+       uint8_t                         max_restarts;
 
        isc_refcount_t                  references;
 
@@ -114,6 +113,7 @@ struct dns_client {
 
 #define DEF_FIND_TIMEOUT       5
 #define DEF_FIND_UDPRETRIES    3
+#define DEF_MAX_RESTARTS       11
 
 #define DNS_CLIENTATTR_OWNCTX                  0x01
 
@@ -517,6 +517,7 @@ dns_client_createx2(isc_mem_t *mctx, isc_appctx_t *actx,
        client->taskmgr = taskmgr;
        client->socketmgr = socketmgr;
        client->timermgr = timermgr;
+       client->max_restarts = DEF_MAX_RESTARTS,
 
        client->task = NULL;
        result = isc_task_create(client->taskmgr, 0, &client->task);
@@ -772,6 +773,14 @@ dns_client_setdlv(dns_client_t *client, dns_rdataclass_t rdclass,
        return (result);
 }
 
+void
+dns_client_setmaxrestarts(dns_client_t *client, uint8_t max_restarts) {
+       REQUIRE(DNS_CLIENT_VALID(client));
+       REQUIRE(max_restarts > 0);
+
+       client->max_restarts = max_restarts;
+}
+
 static isc_result_t
 getrdataset(isc_mem_t *mctx, dns_rdataset_t **rdatasetp) {
        dns_rdataset_t *rdataset;
@@ -1176,7 +1185,9 @@ client_resfind(resctx_t *rctx, dns_fetchevent_t *event) {
                /*
                 * Limit the number of restarts.
                 */
-               if (want_restart && rctx->restarts == MAX_RESTARTS) {
+               if (want_restart &&
+                   rctx->restarts == rctx->client->max_restarts)
+               {
                        want_restart = false;
                        result = ISC_R_QUOTA;
                        send_event = true;

diff --git a/lib/dns/include/dns/client.h b/lib/dns/include/dns/client.h
index f71d16fab4865f33abd1049f4e13236d5e9e8732..a7995e000bfe14f7cfd0db35687d943b5bb8cc0d 100644 (file)
--- a/lib/dns/include/dns/client.h
+++ b/lib/dns/include/dns/client.h
@@ -271,6 +271,19 @@ dns_client_clearservers(dns_client_t *client, dns_rdataclass_t rdclass,
  *\li  Anything else                           Failure.
  */
 
+void
+dns_client_setmaxrestarts(dns_client_t *client, uint8_t max_restarts);
+/*%<
+ * Set the number of permissible chained queries before we give up,
+ * to prevent CNAME loops. This defaults to 11.
+ *
+ * Requires:
+ *
+ *\li  'client' is a valid client.
+
+ *\li  'max_restarts' is greater than 0.
+ */
+
 isc_result_t
 dns_client_setdlv(dns_client_t *client, dns_rdataclass_t rdclass,
                  const char *dlvname);

diff --git a/lib/dns/include/dns/view.h b/lib/dns/include/dns/view.h
index 53f1db1235cc845a0e04b49d698f6db012eb1549..f7c39ab9c0451c399a59b2d1c28b944c6d5aeca9 100644 (file)
--- a/lib/dns/include/dns/view.h
+++ b/lib/dns/include/dns/view.h
@@ -182,6 +182,7 @@ struct dns_view {
        dns_dlzdblist_t                 dlz_unsearched;
        uint32_t                        fail_ttl;
        dns_badcache_t                  *failcache;
+       uint8_t                         max_restarts;
 
        /*
         * Configurable data for server use only,
@@ -1345,6 +1346,18 @@ dns_view_setviewrevert(dns_view_t *view);
  */
 
 
+void
+dns_view_setmaxrestarts(dns_view_t *view, uint8_t max_restarts);
+/*%<
+ * Set the number of permissible chained queries before we give up,
+ * to prevent CNAME loops. This defaults to 11.
+ *
+ * Requires:
+ *
+ *\li  'view' is valid;
+ *\li  'max_restarts' is greater than 0.
+ */
+
 ISC_LANG_ENDDECLS
 
 #endif /* DNS_VIEW_H */

diff --git a/lib/dns/view.c b/lib/dns/view.c
index f01b4dea0fbf7f22e4dd0e54532c24478d0d99ce..e5c42ef1cb64aa1f13da7ac103259a8dd3a15bdf 100644 (file)
--- a/lib/dns/view.c
+++ b/lib/dns/view.c
@@ -79,6 +79,12 @@ static void resolver_shutdown(isc_task_t *task, isc_event_t *event);
 static void adb_shutdown(isc_task_t *task, isc_event_t *event);
 static void req_shutdown(isc_task_t *task, isc_event_t *event);
 
+/*%
+ * Default maximum number of chained queries before we give up
+ * to prevent CNAME loops.
+ */
+#define DEFAULT_MAX_RESTARTS 11
+
 isc_result_t
 dns_view_create(isc_mem_t *mctx, dns_rdataclass_t rdclass,
                const char *name, dns_view_t **viewp)
@@ -264,6 +270,8 @@ dns_view_create(isc_mem_t *mctx, dns_rdataclass_t rdclass,
        view->dtenv = NULL;
        view->dttypes = 0;
 
+       view->max_restarts = DEFAULT_MAX_RESTARTS;
+
        result = isc_mutex_init(&view->new_zone_lock);
        if (result != ISC_R_SUCCESS) {
                goto cleanup_failcache;
@@ -2448,3 +2456,11 @@ dns_view_setviewrevert(dns_view_t *view) {
                dns_zt_setviewrevert(zonetable);
        }
 }
+
+void
+dns_view_setmaxrestarts(dns_view_t *view, uint8_t max_restarts) {
+       REQUIRE(DNS_VIEW_VALID(view));
+       REQUIRE(max_restarts > 0);
+
+       view->max_restarts = max_restarts;
+}

diff --git a/lib/dns/win32/libdns.def.in b/lib/dns/win32/libdns.def.in
index 1cd8ebb4c85b5ac4959a3d12f0f3c3a38a692a61..a0a8f625563b6c1b60de88a7651217327027b340 100644 (file)
--- a/lib/dns/win32/libdns.def.in
+++ b/lib/dns/win32/libdns.def.in
@@ -168,6 +168,7 @@ dns_client_mctx
 dns_client_request
 dns_client_resolve
 dns_client_setdlv
+dns_client_setmaxrestarts
 dns_client_setservers
 dns_client_startrequest
 dns_client_startresolve
@@ -1135,6 +1136,7 @@ dns_view_setdynamickeyring
 dns_view_setfailttl
 dns_view_sethints
 dns_view_setkeyring
+dns_view_setmaxrestarts
 dns_view_setnewzones
 dns_view_setresquerystats
 dns_view_setresstats