YT-21317: Introduce cache_key_mode

### Changelog entry
Type: feature
Component: proxy

Add cache_key_mode to control the granularity of credential caching.
commit_hash:1f185fd948ee1c4d7dcd65c757425b8e88794424

Author: babenko

yt/yt/core/net/address.cpp

@@ -709,6 +709,13 @@ bool TIP6Address::FromString(TStringBuf str, TIP6Address* address)
     return true;
 }
 
+bool TIP6Address::IsMtn() const
+{
+    static const auto BackboneNetwork = TIP6Network::FromString("2a02:6b8:c00::/40");
+    static const auto FastboneNetwork = TIP6Network::FromString("2a02:6b8:fc00::/40");
+    return BackboneNetwork.Contains(*this) || FastboneNetwork.Contains(*this);
+}
+
 void FormatValue(TStringBuilderBase* builder, const TIP6Address& address, TStringBuf /*spec*/)
 {
     const auto* parts = reinterpret_cast<const ui16*>(address.GetRawBytes());
@@ -1187,7 +1194,7 @@ TMtnAddress& TMtnAddress::SetHost(ui64 host)
     return *this;
 }
 
-const TIP6Address& TMtnAddress::ToIP6Address() const
+TIP6Address TMtnAddress::ToIP6Address() const
 {
     return Address_;
 }

yt/yt/core/net/address.h

@@ -123,6 +123,8 @@ class TIP6Address
     const ui32* GetRawDWords() const;
     ui32* GetRawDWords();
 
+    bool IsMtn() const;
+
 private:
     std::array<ui8, ByteSize> Raw_ = {};
 };
@@ -226,7 +228,6 @@ class TMtnAddress
 {
 public:
     TMtnAddress() = default;
-
     TMtnAddress(TIP6Address address);
 
     ui64 GetPrefix() const;
@@ -241,11 +242,10 @@ class TMtnAddress
     ui64 GetHost() const;
     TMtnAddress& SetHost(ui64 host);
 
-    const TIP6Address& ToIP6Address() const;
+    TIP6Address ToIP6Address() const;
 
 private:
     ui64 GetBytesRangeValue(int leftIndex, int rightIndex) const;
-
     void SetBytesRangeValue(int leftIndex, int rightIndex, ui64 value);
 
     static constexpr int HostOffsetInBytes = 0;

yt/yt/core/net/unittests/network_address_ut.cpp

@@ -325,7 +325,16 @@ TEST(TIP6AddressTest, ToStringFromStringRandom)
     }
 }
 
-TEST(TMtnAddressTest, SimpleTest)
+TEST(TIP6AddressTest, IsMtn)
+{
+    EXPECT_TRUE(TIP6Address::FromString("2a02:6b8:c23:130:0:4397:571f:0").IsMtn());
+    EXPECT_TRUE(TIP6Address::FromString("2a02:6b8:fc00:c21b:0:4397:ead:0").IsMtn());
+    EXPECT_FALSE(TIP6Address::FromString("fe80::5054:ff:fe12:3456").IsMtn());
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+TEST(TMtnAddressTest, Simple)
 {
     TMtnAddress address(TIP6Address::FromString("1361:24ad:4326:bda1:8432:a3fe:3f6c:4b38"));
     EXPECT_EQ(address.GetPrefix(), 0x136124ad43u);
@@ -353,7 +362,7 @@ TEST(TMtnAddressTest, SimpleTest)
 
 ////////////////////////////////////////////////////////////////////////////////
 
-TEST(InferYPCluster, ValidFqdns)
+TEST(TInferYPClusterTest, ValidFqdns)
 {
     TString gencfgHostName = "sas1-5535-9d7.sas-test.yp.gencfg-c.yandex.net";
     TString ypHostName = "noqpmfiudzbb4hvs.man.yp-c.yandex.net";
@@ -362,7 +371,7 @@ TEST(InferYPCluster, ValidFqdns)
     EXPECT_EQ(InferYPClusterFromHostName(ypHostName), "man");
 }
 
-TEST(InferYPCluster, InvalidFqdn)
+TEST(TInferYPClusterTest, InvalidFqdn)
 {
     TString hostName = "noqpmfiudzbb4hvs..yp-c.yandex.net";
 
@@ -372,9 +381,7 @@ TEST(InferYPCluster, InvalidFqdn)
     EXPECT_EQ(InferYPClusterFromHostName("yandex.net"), std::nullopt);
 }
 
-////////////////////////////////////////////////////////////////////////////////
-
-TEST(InferYTCluster, ClusterUrls)
+TEST(TInferYPClusterTest, ClusterUrls)
 {
     EXPECT_EQ(InferYTClusterFromClusterUrl("hume"), "hume");
     EXPECT_EQ(InferYTClusterFromClusterUrl("http://yp-sas.yt.yandex.net"), "yp-sas");