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241 lines
8.3 KiB
241 lines
8.3 KiB
8 months ago
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From 128b3b676eb9413b4d25fb29c560895cfbbfa92e Mon Sep 17 00:00:00 2001
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From: Evan Hunt <each@isc.org>
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Date: Thu, 1 Sep 2022 16:05:04 -0700
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Subject: [PATCH] add an update quota
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limit the number of simultaneous DNS UPDATE events that can be
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processed by adding a quota for update and update forwarding.
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this quota currently, arbitrarily, defaults to 100.
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also add a statistics counter to record when the update quota
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has been exceeded.
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(cherry picked from commit 7c47254a140c3e9cf383cda73c7b6a55c4782826)
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---
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bin/named/bind9.xsl | 2 +-
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bin/named/bind9.xsl.h | 8 +++++++-
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bin/named/include/named/server.h | 7 ++++++-
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bin/named/server.c | 3 +++
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bin/named/statschannel.c | 5 +++--
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bin/named/update.c | 34 +++++++++++++++++++++++++++++++-
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doc/arm/Bv9ARM-book.xml | 15 ++++++++++++++
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7 files changed, 68 insertions(+), 6 deletions(-)
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diff --git a/bin/named/bind9.xsl b/bin/named/bind9.xsl
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index 9a1c6ff..85fd4c4 100644
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--- a/bin/named/bind9.xsl
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+++ b/bin/named/bind9.xsl
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@@ -12,7 +12,7 @@
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<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns="http://www.w3.org/1999/xhtml" version="1.0">
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<xsl:output method="html" indent="yes" version="4.0"/>
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- <xsl:template match="statistics[@version="3.8"]">
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+ <xsl:template match="statistics[@version="3.8.1"]">
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<html>
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<head>
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<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script>
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diff --git a/bin/named/bind9.xsl.h b/bin/named/bind9.xsl.h
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index 9ce8cd7..5e0a892 100644
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--- a/bin/named/bind9.xsl.h
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+++ b/bin/named/bind9.xsl.h
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@@ -17,7 +17,13 @@ static char xslmsg[] =
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"\n"
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"<xsl:stylesheet xmlns:xsl=\"http://www.w3.org/1999/XSL/Transform\" xmlns=\"http://www.w3.org/1999/xhtml\" version=\"1.0\">\n"
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" <xsl:output method=\"html\" indent=\"yes\" version=\"4.0\"/>\n"
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- " <xsl:template match=\"statistics[@version="3.8"]\">\n"
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+#if 0
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+ " <!-- the version number **below** must match version in "
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+ "bin/named/statschannel.c -->\n"
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+ " <!-- don't forget to update \"/xml/v<STATS_XML_VERSION_MAJOR>\" in "
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+ "the HTTP endpoints listed below -->\n"
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+#endif
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+ " <xsl:template match=\"statistics[@version="3.8.1"]\">\n"
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" <html>\n"
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" <head>\n"
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" <script type=\"text/javascript\" src=\"https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js\"></script>\n"
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diff --git a/bin/named/include/named/server.h b/bin/named/include/named/server.h
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index 08a02dc..259acc7 100644
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--- a/bin/named/include/named/server.h
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+++ b/bin/named/include/named/server.h
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@@ -137,6 +137,9 @@ struct ns_server {
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uint16_t transfer_tcp_message_size;
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isc_rng_t * rngctx;
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+
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+/* CVE-2022-3094 */
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+ isc_quota_t updquota;
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};
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struct ns_altsecret {
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@@ -230,7 +233,9 @@ enum {
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dns_nsstatscounter_trystale = 59,
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dns_nsstatscounter_usedstale = 60,
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- dns_nsstatscounter_max = 61
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+ dns_nsstatscounter_updatequota = 61,
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+
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+ dns_nsstatscounter_max = 62
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};
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/*%
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diff --git a/bin/named/server.c b/bin/named/server.c
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index 2d2fa0e..f09b895 100644
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--- a/bin/named/server.c
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+++ b/bin/named/server.c
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@@ -9143,6 +9143,8 @@ ns_server_create(isc_mem_t *mctx, ns_server_t **serverp) {
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RUNTIME_CHECK(result == ISC_R_SUCCESS);
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result = isc_quota_init(&server->recursionquota, 100);
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RUNTIME_CHECK(result == ISC_R_SUCCESS);
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+ result = isc_quota_init(&server->updquota, 100);
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+ RUNTIME_CHECK(result == ISC_R_SUCCESS);
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result = dns_aclenv_init(mctx, &server->aclenv);
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RUNTIME_CHECK(result == ISC_R_SUCCESS);
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@@ -9410,6 +9412,7 @@ ns_server_destroy(ns_server_t **serverp) {
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dns_aclenv_destroy(&server->aclenv);
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+ isc_quota_destroy(&server->updquota);
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isc_quota_destroy(&server->recursionquota);
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isc_quota_destroy(&server->tcpquota);
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isc_quota_destroy(&server->xfroutquota);
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diff --git a/bin/named/statschannel.c b/bin/named/statschannel.c
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index 56a9c21..1e8723c 100644
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--- a/bin/named/statschannel.c
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+++ b/bin/named/statschannel.c
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@@ -300,6 +300,7 @@ init_desc(void) {
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SET_NSSTATDESC(reclimitdropped,
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"queries dropped due to recursive client limit",
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"RecLimitDropped");
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+ SET_NSSTATDESC(updatequota, "Update quota exceeded", "UpdateQuota");
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SET_NSSTATDESC(trystale,
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"attempts to use stale cache data after lookup failure",
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"QryTryStale");
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@@ -1546,7 +1547,7 @@ generatexml(ns_server_t *server, uint32_t flags,
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ISC_XMLCHAR "type=\"text/xsl\" href=\"/bind9.xsl\""));
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TRY0(xmlTextWriterStartElement(writer, ISC_XMLCHAR "statistics"));
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TRY0(xmlTextWriterWriteAttribute(writer, ISC_XMLCHAR "version",
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- ISC_XMLCHAR "3.8"));
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+ ISC_XMLCHAR "3.8.1"));
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/* Set common fields for statistics dump */
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dumparg.type = isc_statsformat_xml;
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@@ -2303,7 +2304,7 @@ generatejson(ns_server_t *server, size_t *msglen,
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/*
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* These statistics are included no matter which URL we use.
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*/
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- obj = json_object_new_string("1.2");
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+ obj = json_object_new_string("1.2.1");
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CHECKMEM(obj);
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json_object_object_add(bindstats, "json-stats-version", obj);
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diff --git a/bin/named/update.c b/bin/named/update.c
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index 6ad7d27..dccc543 100644
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--- a/bin/named/update.c
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+++ b/bin/named/update.c
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@@ -1526,6 +1526,17 @@ send_update_event(ns_client_t *client, dns_zone_t *zone) {
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isc_task_t *zonetask = NULL;
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ns_client_t *evclient;
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+ result = isc_quota_attach(&ns_g_server->updquota,
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+ &(isc_quota_t *){ NULL });
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+ if (result != ISC_R_SUCCESS) {
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+ update_log(client, zone, LOGLEVEL_PROTOCOL,
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+ "update failed: too many DNS UPDATEs queued (%s)",
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+ isc_result_totext(result));
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+ isc_stats_increment(ns_g_server->nsstats,
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+ dns_nsstatscounter_updatequota);
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+ CHECK(DNS_R_DROP);
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+ }
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+
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event = (update_event_t *)
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isc_event_allocate(client->mctx, client, DNS_EVENT_UPDATE,
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update_action, NULL, sizeof(*event));
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@@ -1652,7 +1663,12 @@ ns_update_start(ns_client_t *client, isc_result_t sigresult) {
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* We are still in the client task context, so we can
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* simply give an error response without switching tasks.
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*/
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- respond(client, result);
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+ if (result == DNS_R_DROP) {
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+ ns_client_next(client, result);
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+ } else {
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+ respond(client, result);
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+ }
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+
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if (zone != NULL)
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dns_zone_detach(&zone);
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}
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@@ -3385,6 +3401,7 @@ updatedone_action(isc_task_t *task, isc_event_t *event) {
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dns_zone_detach(&uev->zone);
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client->nupdates--;
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respond(client, uev->result);
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+ isc_quota_detach(&(isc_quota_t *){ &ns_g_server->updquota });
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isc_event_free(&event);
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ns_client_detach(&client);
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}
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@@ -3402,6 +3419,8 @@ forward_fail(isc_task_t *task, isc_event_t *event) {
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INSIST(client->nupdates > 0);
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client->nupdates--;
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respond(client, DNS_R_SERVFAIL);
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+
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+ isc_quota_detach(&(isc_quota_t *){ &ns_g_server->updquota });
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isc_event_free(&event);
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ns_client_detach(&client);
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}
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@@ -3439,6 +3458,8 @@ forward_done(isc_task_t *task, isc_event_t *event) {
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client->nupdates--;
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ns_client_sendraw(client, uev->answer);
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dns_message_detach(&uev->answer);
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+
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+ isc_quota_detach(&(isc_quota_t *){ &ns_g_server->updquota });
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isc_event_free(&event);
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ns_client_detach(&client);
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}
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@@ -3472,6 +3493,17 @@ send_forward_event(ns_client_t *client, dns_zone_t *zone) {
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isc_task_t *zonetask = NULL;
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ns_client_t *evclient;
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+ result = isc_quota_attach(&ns_g_server->updquota,
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+ &(isc_quota_t *){ NULL });
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+ if (result != ISC_R_SUCCESS) {
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+ update_log(client, zone, LOGLEVEL_PROTOCOL,
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+ "update failed: too many DNS UPDATEs queued (%s)",
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+ isc_result_totext(result));
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+ isc_stats_increment(ns_g_server->nsstats,
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+ dns_nsstatscounter_updatequota);
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+ return (DNS_R_DROP);
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+ }
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+
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/*
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* This may take some time so replace this client.
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*/
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diff --git a/doc/arm/Bv9ARM-book.xml b/doc/arm/Bv9ARM-book.xml
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index c17f168..9aca6d7 100644
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--- a/doc/arm/Bv9ARM-book.xml
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+++ b/doc/arm/Bv9ARM-book.xml
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@@ -15105,6 +15105,21 @@ HOST-127.EXAMPLE. MX 0 .
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</para>
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</entry>
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</row>
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+ <row rowsep="0">
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+ <entry colname="1">
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+ <para><command>UpdateQuota</command></para>
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+ </entry>
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+ <entry colname="2">
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+ <para><command/></para>
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+ </entry>
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+ <entry colname="3">
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+ <para>
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+ This indicates the number of times a dynamic update or update
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+ forwarding request was rejected because the number of pending
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+ requests exceeded the update quota.
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+ </para>
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+ </entry>
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+ </row>
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<row rowsep="0">
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<entry colname="1">
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<para><command>RateDropped</command></para>
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--
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2.39.2
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