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)

diff --git a/bin/delv/delv.c b/bin/delv/delv.c
index c7506295170467cd19d2b11a42b1836c73113498..650d8cb61b21df22cebaf1916aab84e5eedc2367 100644 (file)
--- a/bin/delv/delv.c
+++ b/bin/delv/delv.c
@@ -76,6 +76,12 @@
 
 #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;
@@ -1776,6 +1782,8 @@ main(int argc, char *argv[]) {
                goto cleanup;
        }
 
+       dns_client_setmaxrestarts(client, MAX_RESTARTS);
+
        /* Set the nameserver */
        if (server != NULL) {
                addserver(client);

diff --git a/lib/dns/client.c b/lib/dns/client.c
index 7ac358df020b4eb555a665e12477d8fb43afc4b0..16f1facb91a4163192b4839e8a0a61f6baa5e063 100644 (file)
--- a/lib/dns/client.c
+++ b/lib/dns/client.c
@@ -60,8 +60,6 @@
 #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 /* ifdef TUNE_LARGE */
@@ -95,6 +93,7 @@ struct dns_client {
 
        unsigned int find_timeout;
        unsigned int find_udpretries;
+       uint8_t max_restarts;
 
        isc_refcount_t references;
 
@@ -105,6 +104,7 @@ struct dns_client {
 
 #define DEF_FIND_TIMEOUT    5
 #define DEF_FIND_UDPRETRIES 3
+#define DEF_MAX_RESTARTS    11
 
 /*%
  * Internal state for a single name resolution procedure
@@ -281,7 +281,11 @@ dns_client_create(isc_mem_t *mctx, isc_appctx_t *actx, isc_taskmgr_t *taskmgr,
 
        client = isc_mem_get(mctx, sizeof(*client));
        *client = (dns_client_t){
-               .actx = actx, .taskmgr = taskmgr, .timermgr = timermgr, .nm = nm
+               .actx = actx,
+               .taskmgr = taskmgr,
+               .timermgr = timermgr,
+               .nm = nm,
+               .max_restarts = DEF_MAX_RESTARTS,
        };
 
        isc_mutex_init(&client->lock);
@@ -474,6 +478,14 @@ dns_client_clearservers(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;
@@ -886,7 +898,9 @@ 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 ec70f92d88306e54e32d5032fee9ec136c001abf..e5908973bd386aff35331471526d72216a7f90ce 100644 (file)
--- a/lib/dns/include/dns/client.h
+++ b/lib/dns/include/dns/client.h
@@ -189,6 +189,19 @@ 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_resolve(dns_client_t *client, const dns_name_t *name,
                   dns_rdataclass_t rdclass, dns_rdatatype_t type,

diff --git a/lib/dns/include/dns/view.h b/lib/dns/include/dns/view.h
index 516c209b92734c983ada695c50d98b3e1f85b423..f5e274ef3d3ddcb9b1b8801b778e8af86861677f 100644 (file)
--- a/lib/dns/include/dns/view.h
+++ b/lib/dns/include/dns/view.h
@@ -193,6 +193,7 @@ struct dns_view {
        dns_badcache_t   *failcache;
        uint32_t          maxrrperset;
        uint32_t          maxtypepername;
+       uint8_t           max_restarts;
 
        /*
         * Configurable data for server use only,
@@ -1427,4 +1428,16 @@ dns_view_setmaxtypepername(dns_view_t *view, uint32_t value);
  * Set the maximum resource record types per owner name that can be cached.
  */
 
+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

diff --git a/lib/dns/view.c b/lib/dns/view.c
index 231041efabd12ab3aa125cdca3ddb731926d7fd5..7b8520acd7e1b9e0526ffadfbc7f0fb16413fa46 100644 (file)
--- a/lib/dns/view.c
+++ b/lib/dns/view.c
@@ -88,6 +88,12 @@ 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) {
@@ -266,6 +272,8 @@ dns_view_create(isc_mem_t *mctx, dns_rdataclass_t rdclass, const char *name,
        view->hooktable = NULL;
        view->hooktable_free = NULL;
 
+       view->max_restarts = DEFAULT_MAX_RESTARTS;
+
        isc_mutex_init(&view->new_zone_lock);
 
        result = dns_order_create(view->mctx, &view->order);
@@ -2780,3 +2788,11 @@ dns_view_setmaxtypepername(dns_view_t *view, uint32_t value) {
                dns_cache_setmaxtypepername(view->cache, value);
        }
 }
+
+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/ns/include/ns/server.h b/lib/ns/include/ns/server.h
index 206c495dc03b89c0afca07d4a1f01534d383886a..6e4309b000cee8428ed941c2e13cb589d74d826f 100644 (file)
--- a/lib/ns/include/ns/server.h
+++ b/lib/ns/include/ns/server.h
@@ -100,6 +100,7 @@ struct ns_server {
        uint16_t       transfer_tcp_message_size;
        bool           interface_auto;
        dns_tkeyctx_t *tkeyctx;
+       uint8_t        max_restarts;
 
        /*% Server id for NSID */
        char *server_id;

diff --git a/lib/ns/query.c b/lib/ns/query.c
index b712fe2fb2ef1aac4c67397d55dc134943681434..5549e202df5bd8710766abd1661a685deb313124 100644 (file)
--- a/lib/ns/query.c
+++ b/lib/ns/query.c
@@ -85,12 +85,6 @@
 #define dns64_bis_return_excluded_addresses 1
 #endif /* if 0 */
 
-/*%
- * Maximum number of chained queries before we give up
- * to prevent CNAME loops.
- */
-#define MAX_RESTARTS 11
-
 #define QUERY_ERROR(qctx, r)                  \
        do {                                  \
                (qctx)->result = r;           \
@@ -2095,10 +2089,10 @@ addname:
        /*
         * In some cases, a record that has been added as additional
         * data may *also* trigger the addition of additional data.
-        * This cannot go more than MAX_RESTARTS levels deep.
+        * This cannot go more than 'max-restarts' levels deep.
         */
        if (trdataset != NULL && dns_rdatatype_followadditional(type)) {
-               if (client->additionaldepth++ < MAX_RESTARTS) {
+               if (client->additionaldepth++ < client->view->max_restarts) {
                        eresult = dns_rdataset_additionaldata(
                                trdataset, fname, query_additional_cb, qctx);
                }
@@ -11945,7 +11939,9 @@ ns_query_done(query_ctx_t *qctx) {
         * Do we need to restart the query (e.g. for CNAME chaining)?
         */
        if (qctx->want_restart) {
-               if (qctx->client->query.restarts < MAX_RESTARTS) {
+               if (qctx->client->query.restarts <
+                   qctx->client->view->max_restarts)
+               {
                        qctx->client->query.restarts++;
                        return (ns__query_start(qctx));
                } else {

diff --git a/lib/ns/server.c b/lib/ns/server.c
index 7b245c39c7370d278533adb9fb1257df803a7230..bea4f36a47eaa6c06237e74201b294c54a15a106 100644 (file)
--- a/lib/ns/server.c
+++ b/lib/ns/server.c
@@ -38,7 +38,7 @@
 isc_result_t
 ns_server_create(isc_mem_t *mctx, ns_matchview_t matchingview,
                 ns_server_t **sctxp) {
-       ns_server_t *sctx;
+       ns_server_t *sctx = NULL;
        isc_result_t result;
 
        REQUIRE(sctxp != NULL && *sctxp == NULL);