From 513f4303347177c5b2d2792aaf245caad51a231f Mon Sep 17 00:00:00 2001
From: Arthur Passos <arthur.ti@outlook.com>
Date: Mon, 30 Jan 2023 12:04:37 -0300
Subject: [PATCH] Add setting to enable/disable reverseDNSQuery function

---
 programs/server/config.d/reverse_dns_function.xml        | 0
 src/Functions/reverseDNSQuery.cpp                        | 9 +++++++++
 tests/config/config.d/reverse_dns_query_function.xml     | 3 +++
 tests/config/install.sh                                  | 1 +
 .../test_reverse_dns_query/configs/config.xml            | 3 ---
 5 files changed, 13 insertions(+), 3 deletions(-)
 create mode 100644 programs/server/config.d/reverse_dns_function.xml
 create mode 100644 tests/config/config.d/reverse_dns_query_function.xml
 delete mode 100644 tests/integration/test_reverse_dns_query/configs/config.xml

diff --git a/programs/server/config.d/reverse_dns_function.xml b/programs/server/config.d/reverse_dns_function.xml
new file mode 100644
index 00000000000..e69de29bb2d
diff --git a/src/Functions/reverseDNSQuery.cpp b/src/Functions/reverseDNSQuery.cpp
index 41adffa8bde..65ce5e859c5 100644
--- a/src/Functions/reverseDNSQuery.cpp
+++ b/src/Functions/reverseDNSQuery.cpp
@@ -6,6 +6,8 @@
 #include <DataTypes/DataTypeArray.h>
 #include <Common/DNSResolver.h>
 #include <Poco/Net/IPAddress.h>
+#include <Interpreters/Context.h>
+#include <Poco/Util/AbstractConfiguration.h>
 
 namespace DB
 {
@@ -14,12 +16,14 @@ namespace ErrorCodes
 {
     extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
     extern const int BAD_ARGUMENTS;
+    extern const int FUNCTION_NOT_ALLOWED;
 }
 
 class ReverseDNSQuery : public IFunction
 {
 public:
     static constexpr auto name = "reverseDNSQuery";
+    static constexpr auto allow_function_config_name = "allow_reverse_dns_query_function";
 
     static FunctionPtr create(ContextPtr)
     {
@@ -33,6 +37,11 @@ public:
 
     ColumnPtr executeImpl(const ColumnsWithTypeAndName & arguments, const DataTypePtr & data_type, size_t input_rows_count) const override
     {
+        if (!Context::getGlobalContextInstance()->getConfigRef().getBool(allow_function_config_name, false))
+        {
+            throw Exception(ErrorCodes::FUNCTION_NOT_ALLOWED, "Function {} is not allowed because {} is not set", name, allow_function_config_name);
+        }
+
         if (arguments.empty())
         {
             throw Exception(ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH, "Function {} requires at least one argument", name);
diff --git a/tests/config/config.d/reverse_dns_query_function.xml b/tests/config/config.d/reverse_dns_query_function.xml
new file mode 100644
index 00000000000..8cd7695b4d3
--- /dev/null
+++ b/tests/config/config.d/reverse_dns_query_function.xml
@@ -0,0 +1,3 @@
+<clickhouse>
+    <allow_reverse_dns_query_function>1</allow_reverse_dns_query_function>
+</clickhouse>
\ No newline at end of file
diff --git a/tests/config/install.sh b/tests/config/install.sh
index 51865665f59..57606e8b876 100755
--- a/tests/config/install.sh
+++ b/tests/config/install.sh
@@ -52,6 +52,7 @@ ln -sf $SRC_PATH/config.d/enable_zero_copy_replication.xml $DEST_SERVER_PATH/con
 ln -sf $SRC_PATH/config.d/nlp.xml $DEST_SERVER_PATH/config.d/
 ln -sf $SRC_PATH/config.d/enable_keeper_map.xml $DEST_SERVER_PATH/config.d/
 ln -sf $SRC_PATH/config.d/display_name.xml $DEST_SERVER_PATH/config.d/
+ln -sf $SRC_PATH/config.d/reverse_dns_query_function.xml $DEST_SERVER_PATH/config.d/
 
 # Not supported with fasttest.
 if [ "${DEST_SERVER_PATH}" = "/etc/clickhouse-server" ]
diff --git a/tests/integration/test_reverse_dns_query/configs/config.xml b/tests/integration/test_reverse_dns_query/configs/config.xml
deleted file mode 100644
index 5ce55afa2a7..00000000000
--- a/tests/integration/test_reverse_dns_query/configs/config.xml
+++ /dev/null
@@ -1,3 +0,0 @@
-<clickhouse>
-    <disable_internal_dns_cache>1</disable_internal_dns_cache>
-</clickhouse>