Core/Networking: Support IPv6

(cherry picked from commit af4dcc93ed04c4f2219c14821b25cb9efeb7e781)

# Conflicts:
#	sql/base/auth_database.sql
#	sql/updates/auth/cata_classic/2024_11_12_00_auth.sql

14 files changed, 118 insertions, 59 deletions

diff --git a/sql/base/auth_database.sql b/sql/base/auth_database.sql
index f4b69295116..85917812ed4 100644
--- a/sql/base/auth_database.sql
+++ b/sql/base/auth_database.sql
@@ -2683,6 +2683,8 @@ CREATE TABLE `realmlist` (
   `name` varchar(32) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci NOT NULL DEFAULT '',
   `address` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci NOT NULL DEFAULT '127.0.0.1',
   `localAddress` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci NOT NULL DEFAULT '127.0.0.1',
+  `address3` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci DEFAULT NULL,
+  `address4` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci DEFAULT NULL,
   `localSubnetMask` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci NOT NULL DEFAULT '255.255.255.0',
   `port` smallint unsigned NOT NULL DEFAULT '8085',
   `icon` tinyint unsigned NOT NULL DEFAULT '0',
@@ -2705,7 +2707,7 @@ CREATE TABLE `realmlist` (
 LOCK TABLES `realmlist` WRITE;
 /*!40000 ALTER TABLE `realmlist` DISABLE KEYS */;
 INSERT INTO `realmlist` VALUES
-(1,'Trinity','127.0.0.1','127.0.0.1','255.255.255.0',8085,0,0,1,0,0,57359,1,1);
+(1,'Trinity','127.0.0.1','127.0.0.1',NULL,NULL,'255.255.255.0',8085,0,0,1,0,0,57359,1,1);
 /*!40000 ALTER TABLE `realmlist` ENABLE KEYS */;
 UNLOCK TABLES;
 
@@ -3148,7 +3150,8 @@ INSERT INTO `updates` VALUES
 ('2024_10_31_00_auth.sql','FCBF83D6981B26DE2807BDF338A3754972535906','RELEASED','2024-10-31 19:29:16',0),
 ('2024_11_02_00_auth.sql','93A7F7A3C3BA586C139B4060180F7E032C535669','RELEASED','2024-11-02 12:35:24',0),
 ('2024_11_06_00_auth.sql','0C8D79745E070CEEE55D9546EC78FE89C5CCB040','RELEASED','2024-11-06 17:27:41',0),
-('2024_11_11_00_auth.sql','F47CDFB857DB4105306739AF4FBBB3C92CA43363','RELEASED','2024-11-11 13:34:09',0);
+('2024_11_11_00_auth.sql','F47CDFB857DB4105306739AF4FBBB3C92CA43363','RELEASED','2024-11-11 13:34:09',0),
+('2024_11_12_00_auth.sql','5A236A557291758C0F2C46FDEC02692E7C53F751','RELEASED','2024-11-12 11:42:13',0);
 /*!40000 ALTER TABLE `updates` ENABLE KEYS */;
 UNLOCK TABLES;
 
diff --git a/sql/updates/auth/cata_classic/2024_11_12_00_auth.sql b/sql/updates/auth/cata_classic/2024_11_12_00_auth.sql
new file mode 100644
index 00000000000..3eb0af6c898
--- /dev/null
+++ b/sql/updates/auth/cata_classic/2024_11_12_00_auth.sql
@@ -0,0 +1,5 @@
+ALTER TABLE `realmlist` 
+  MODIFY `address` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci NULL DEFAULT '127.0.0.1' AFTER `name`,
+  MODIFY `localAddress` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci NULL DEFAULT '127.0.0.1' AFTER `address`,
+  ADD `address3` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci NULL DEFAULT NULL AFTER `localAddress`,
+  ADD `address4` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci NULL DEFAULT NULL AFTER `address3`;
diff --git a/src/common/Asio/Resolver.h b/src/common/Asio/Resolver.h
index 01399e435e5..01fd3127abe 100644
--- a/src/common/Asio/Resolver.h
+++ b/src/common/Asio/Resolver.h
@@ -21,7 +21,8 @@
 #include "IoContext.h"
 #include "Optional.h"
 #include <boost/asio/ip/tcp.hpp>
-#include <string>
+#include <string_view>
+#include <vector>
 
 namespace Trinity
 {
@@ -35,7 +36,7 @@ namespace Trinity
         public:
             explicit Resolver(IoContext& ioContext) : _impl(ioContext) { }
 
-            Optional<boost::asio::ip::tcp::endpoint> Resolve(boost::asio::ip::tcp const& protocol, std::string const& host, std::string const& service)
+            Optional<boost::asio::ip::tcp::endpoint> Resolve(boost::asio::ip::tcp const& protocol, std::string_view host, std::string_view service)
             {
                 boost::system::error_code ec;
                 boost::asio::ip::resolver_base::flags flagsResolver = boost::asio::ip::resolver_base::all_matching;
@@ -46,6 +47,18 @@ namespace Trinity
                 return results.begin()->endpoint();
             }
 
+            std::vector<boost::asio::ip::tcp::endpoint> ResolveAll(std::string_view host, std::string_view service)
+            {
+                boost::system::error_code ec;
+                boost::asio::ip::resolver_base::flags flagsResolver = boost::asio::ip::resolver_base::all_matching;
+                boost::asio::ip::tcp::resolver::results_type results = _impl.resolve(host, service, flagsResolver, ec);
+                std::vector<boost::asio::ip::tcp::endpoint> result;
+                if (!ec)
+                    std::ranges::transform(results, std::back_inserter(result), [](boost::asio::ip::tcp::resolver::results_type::value_type const& entry) { return entry.endpoint(); });
+
+                return result;
+            }
+
         private:
             boost::asio::ip::tcp::resolver _impl;
         };
diff --git a/src/server/bnetserver/REST/LoginRESTService.cpp b/src/server/bnetserver/REST/LoginRESTService.cpp
index c9aabb248a3..b2ce7ddab56 100644
--- a/src/server/bnetserver/REST/LoginRESTService.cpp
+++ b/src/server/bnetserver/REST/LoginRESTService.cpp
@@ -77,28 +77,26 @@ bool LoginRESTService::StartNetwork(Trinity::Asio::IoContext& ioContext, std::st
     _bindIP = bindIp;
     _port = port;
 
+    using namespace std::string_literals;
+    std::array<std::string, 2> configKeys = { { "LoginREST.ExternalAddress"s, "LoginREST.LocalAddress"s } };
+
     Trinity::Asio::Resolver resolver(ioContext);
 
-    _hostnames[0] = sConfigMgr->GetStringDefault("LoginREST.ExternalAddress", "127.0.0.1");
-    Optional<boost::asio::ip::tcp::endpoint> externalAddress = resolver.Resolve(boost::asio::ip::tcp::v4(), _hostnames[0], std::to_string(_port));
-    if (!externalAddress)
+    for (std::size_t i = 0; i < _hostnames.size(); ++i)
     {
-        TC_LOG_ERROR("server.http.login", "Could not resolve LoginREST.ExternalAddress {}", _hostnames[0]);
-        return false;
-    }
+        _hostnames[i].first = sConfigMgr->GetStringDefault(configKeys[i], "127.0.0.1");
 
-    _addresses[0] = externalAddress->address();
+        std::ranges::transform(resolver.ResolveAll(_hostnames[i].first, ""),
+            std::back_inserter(_hostnames[i].second),
+            [](boost::asio::ip::tcp::endpoint const& endpoint) { return endpoint.address(); });
 
-    _hostnames[1] = sConfigMgr->GetStringDefault("LoginREST.LocalAddress", "127.0.0.1");
-    Optional<boost::asio::ip::tcp::endpoint> localAddress = resolver.Resolve(boost::asio::ip::tcp::v4(), _hostnames[1], std::to_string(_port));
-    if (!localAddress)
-    {
-        TC_LOG_ERROR("server.http.login", "Could not resolve LoginREST.LocalAddress {}", _hostnames[1]);
-        return false;
+        if (_hostnames[i].second.empty())
+        {
+            TC_LOG_ERROR("server.http.login", "Could not resolve {} {}", configKeys[i], _hostnames[i].first);
+            return false;
+        }
     }
 
-    _addresses[1] = localAddress->address();
-
     // set up form inputs
     JSON::Login::FormInput* input;
     _formInputs.set_type(JSON::Login::LOGIN_FORM);
@@ -129,13 +127,14 @@ bool LoginRESTService::StartNetwork(Trinity::Asio::IoContext& ioContext, std::st
 
 std::string const& LoginRESTService::GetHostnameForClient(boost::asio::ip::address const& address) const
 {
-    if (auto addressIndex = Trinity::Net::SelectAddressForClient(address, _addresses))
-        return _hostnames[*addressIndex];
+    for (std::size_t i = 0; i < _hostnames.size(); ++i)
+        if (Trinity::Net::SelectAddressForClient(address, _hostnames[i].second))
+            return _hostnames[i].first;
 
     if (address.is_loopback())
-        return _hostnames[1];
+        return _hostnames[1].first;
 
-    return _hostnames[0];
+    return _hostnames[0].first;
 }
 
 std::string LoginRESTService::ExtractAuthorization(HttpRequest const& request)
diff --git a/src/server/bnetserver/REST/LoginRESTService.h b/src/server/bnetserver/REST/LoginRESTService.h
index bcc99808505..079bb6fca9c 100644
--- a/src/server/bnetserver/REST/LoginRESTService.h
+++ b/src/server/bnetserver/REST/LoginRESTService.h
@@ -83,8 +83,7 @@ private:
     JSON::Login::FormInputs _formInputs;
     std::string _bindIP;
     uint16 _port;
-    std::array<std::string, 2> _hostnames;
-    std::array<boost::asio::ip::address, 2> _addresses;
+    std::array<std::pair<std::string, std::vector<boost::asio::ip::address>>, 2> _hostnames;
     uint32 _loginTicketDuration;
 };
 }
diff --git a/src/server/bnetserver/bnetserver.conf.dist b/src/server/bnetserver/bnetserver.conf.dist
index 94fd3964590..1936d57d3fa 100644
--- a/src/server/bnetserver/bnetserver.conf.dist
+++ b/src/server/bnetserver/bnetserver.conf.dist
@@ -83,6 +83,7 @@ LoginREST.TicketDuration=3600
 #
 #    BindIP
 #        Description: Bind auth server to IP/hostname
+#                     Using IPv6 address (such as "::") will enable both IPv4 and IPv6 connections
 #        Default:     "0.0.0.0" - (Bind to all IPs on the system)
 
 BindIP = "0.0.0.0"
diff --git a/src/server/database/Database/Implementation/LoginDatabase.cpp b/src/server/database/Database/Implementation/LoginDatabase.cpp
index c916a0ac458..ca1930e4b06 100644
--- a/src/server/database/Database/Implementation/LoginDatabase.cpp
+++ b/src/server/database/Database/Implementation/LoginDatabase.cpp
@@ -23,7 +23,7 @@ void LoginDatabaseConnection::DoPrepareStatements()
     if (!m_reconnecting)
         m_stmts.resize(MAX_LOGINDATABASE_STATEMENTS);
 
-    PrepareStatement(LOGIN_SEL_REALMLIST, "SELECT id, name, address, localAddress, port, icon, flag, timezone, allowedSecurityLevel, population, gamebuild, Region, Battlegroup FROM realmlist WHERE flag <> 3 ORDER BY name", CONNECTION_SYNCH);
+    PrepareStatement(LOGIN_SEL_REALMLIST, "SELECT id, name, address, localAddress, address3, address4, port, icon, flag, timezone, allowedSecurityLevel, population, gamebuild, Region, Battlegroup FROM realmlist WHERE flag <> 3 ORDER BY name", CONNECTION_SYNCH);
     PrepareStatement(LOGIN_UPD_REALM_POPULATION, "UPDATE realmlist SET population = ? WHERE id = ?", CONNECTION_ASYNC);
     PrepareStatement(LOGIN_DEL_EXPIRED_IP_BANS, "DELETE FROM ip_banned WHERE unbandate<>bandate AND unbandate<=UNIX_TIMESTAMP()", CONNECTION_ASYNC);
     PrepareStatement(LOGIN_UPD_EXPIRED_ACCOUNT_BANS, "UPDATE account_banned SET active = 0 WHERE active = 1 AND unbandate<>bandate AND unbandate<=UNIX_TIMESTAMP()", CONNECTION_ASYNC);
diff --git a/src/server/game/Server/WorldSession.cpp b/src/server/game/Server/WorldSession.cpp
index 1d3e5eb4cd7..0794ebf57dc 100644
--- a/src/server/game/Server/WorldSession.cpp
+++ b/src/server/game/Server/WorldSession.cpp
@@ -818,8 +818,23 @@ void WorldSession::SendConnectToInstance(WorldPackets::Auth::ConnectToSerial ser
     }
     else
     {
-        memcpy(connectTo.Payload.Where.Address.V6.data(), instanceAddress.to_v6().to_bytes().data(), 16);
-        connectTo.Payload.Where.Type = WorldPackets::Auth::ConnectTo::IPv6;
+        // client always uses v4 address for loopback and v4 mapped addresses
+        boost::asio::ip::address_v6 v6 = instanceAddress.to_v6();
+        if (v6.is_loopback())
+        {
+            memcpy(connectTo.Payload.Where.Address.V4.data(), boost::asio::ip::address_v4::loopback().to_bytes().data(), 4);
+            connectTo.Payload.Where.Type = WorldPackets::Auth::ConnectTo::IPv4;
+        }
+        else if (v6.is_v4_mapped())
+        {
+            memcpy(connectTo.Payload.Where.Address.V4.data(), Trinity::Net::make_address_v4(boost::asio::ip::v4_mapped, v6).to_bytes().data(), 4);
+            connectTo.Payload.Where.Type = WorldPackets::Auth::ConnectTo::IPv4;
+        }
+        else
+        {
+            memcpy(connectTo.Payload.Where.Address.V6.data(), v6.to_bytes().data(), 16);
+            connectTo.Payload.Where.Type = WorldPackets::Auth::ConnectTo::IPv6;
+        }
     }
     connectTo.Con = CONNECTION_TYPE_INSTANCE;
 
diff --git a/src/server/game/Server/WorldSocket.cpp b/src/server/game/Server/WorldSocket.cpp
index 2bdde59e956..f12dd005750 100644
--- a/src/server/game/Server/WorldSocket.cpp
+++ b/src/server/game/Server/WorldSocket.cpp
@@ -445,7 +445,7 @@ WorldSocket::ReadDataHandlerResult WorldSocket::ReadDataHandler()
             return ReadDataHandlerResult::Error;
         case CMSG_LOG_DISCONNECT:
             LogOpcodeText(opcode, sessionGuard);
-            packet.rfinish();   // contains uint32 disconnectReason;
+            TC_LOG_DEBUG("network", "WorldSocket::ReadDataHandler: client {} sent CMSG_LOG_DISCONNECT reason {}", GetRemoteIpAddress().to_string(), packet.read<uint32>());
             break;
         case CMSG_ENABLE_NAGLE:
             LogOpcodeText(opcode, sessionGuard);
diff --git a/src/server/shared/Networking/AsyncAcceptor.h b/src/server/shared/Networking/AsyncAcceptor.h
index 7f1cb34204c..95e25e02166 100644
--- a/src/server/shared/Networking/AsyncAcceptor.h
+++ b/src/server/shared/Networking/AsyncAcceptor.h
@@ -22,6 +22,7 @@
 #include "IpAddress.h"
 #include "Log.h"
 #include <boost/asio/ip/tcp.hpp>
+#include <boost/asio/ip/v6_only.hpp>
 #include <atomic>
 #include <functional>
 
@@ -88,6 +89,11 @@ public:
         }
 #endif
 
+        // v6_only is enabled on some *BSD distributions by default
+        // we want to allow both v4 and v6 connections to the same listener
+        if (_endpoint.protocol() == boost::asio::ip::tcp::v6())
+            _acceptor.set_option(boost::asio::ip::v6_only(false));
+
         _acceptor.bind(_endpoint, errorCode);
         if (errorCode)
         {
diff --git a/src/server/shared/Realm/Realm.cpp b/src/server/shared/Realm/Realm.cpp
index 42ac0c3f64b..c06a53dfe9c 100644
--- a/src/server/shared/Realm/Realm.cpp
+++ b/src/server/shared/Realm/Realm.cpp
@@ -26,7 +26,7 @@ void Realm::SetName(std::string name)
 {
     Name = name;
     NormalizedName = std::move(name);
-    NormalizedName.erase(std::remove_if(NormalizedName.begin(), NormalizedName.end(), ::isspace), NormalizedName.end());
+    std::erase_if(NormalizedName, [](char c) { return std::isspace(static_cast<unsigned char>(c)); });
 }
 
 boost::asio::ip::address Realm::GetAddressForClient(boost::asio::ip::address const& clientAddr) const
@@ -34,7 +34,7 @@ boost::asio::ip::address Realm::GetAddressForClient(boost::asio::ip::address con
     if (auto addressIndex = Trinity::Net::SelectAddressForClient(clientAddr, Addresses))
         return Addresses[*addressIndex];
 
-    if (clientAddr.is_loopback())
+    if (Addresses.size() > 1 && clientAddr.is_loopback())
         return Addresses[1];
 
     return Addresses[0];
diff --git a/src/server/shared/Realm/RealmList.cpp b/src/server/shared/Realm/RealmList.cpp
index fcee58c47d0..9fe48277353 100644
--- a/src/server/shared/Realm/RealmList.cpp
+++ b/src/server/shared/Realm/RealmList.cpp
@@ -80,7 +80,7 @@ void RealmList::Close()
 }
 
 void RealmList::UpdateRealm(Realm& realm, Battlenet::RealmHandle const& id, uint32 build, std::string const& name,
-    boost::asio::ip::address&& address, boost::asio::ip::address&& localAddr,
+    std::vector<boost::asio::ip::address>&& addresses,
     uint16 port, uint8 icon, RealmFlags flag, uint8 timezone, AccountTypes allowedSecurityLevel,
     RealmPopulationState population)
 {
@@ -93,9 +93,7 @@ void RealmList::UpdateRealm(Realm& realm, Battlenet::RealmHandle const& id, uint
     realm.Timezone = timezone;
     realm.AllowedSecurityLevel = allowedSecurityLevel;
     realm.PopulationLevel = population;
-    realm.Addresses.resize(2);
-    realm.Addresses[0] = std::move(address);
-    realm.Addresses[1] = std::move(localAddr);
+    realm.Addresses = std::move(addresses);
     realm.Port = port;
 }
 
@@ -121,48 +119,65 @@ void RealmList::UpdateRealms()
             Field* fields = result->Fetch();
             uint32 realmId = fields[0].GetUInt32();
             std::string name = fields[1].GetString();
-            std::string externalAddressString = fields[2].GetString();
-            std::string localAddressString = fields[3].GetString();
+            std::vector<boost::asio::ip::address> addresses;
 
-            Optional<boost::asio::ip::tcp::endpoint> externalAddress = _resolver->Resolve(boost::asio::ip::tcp::v4(), externalAddressString, "");
-            if (!externalAddress)
+            for (std::size_t i = 0; i < 4; ++i)
             {
-                TC_LOG_ERROR("realmlist", "Could not resolve address {} for realm \"{}\" id {}", externalAddressString, name, realmId);
-                continue;
+                if (fields[2 + i].IsNull())
+                    continue;
+
+                for (boost::asio::ip::tcp::endpoint const& endpoint : _resolver->ResolveAll(fields[2 + i].GetStringView(), ""))
+                {
+                    boost::asio::ip::address address = endpoint.address();
+                    if (std::ranges::find(addresses, address) != addresses.end())
+                        continue;
+
+                    addresses.push_back(std::move(address));
+                }
             }
 
-            Optional<boost::asio::ip::tcp::endpoint> localAddress = _resolver->Resolve(boost::asio::ip::tcp::v4(), localAddressString, "");
-            if (!localAddress)
+            if (addresses.empty())
             {
-                TC_LOG_ERROR("realmlist", "Could not resolve localAddress {} for realm \"{}\" id {}", localAddressString, name, realmId);
+                TC_LOG_ERROR("realmlist", "Could not resolve any address for realm \"{}\" id {}", name, realmId);
                 continue;
             }
 
-            uint16 port = fields[4].GetUInt16();
-            uint8 icon = fields[5].GetUInt8();
+            uint16 port = fields[6].GetUInt16();
+            uint8 icon = fields[7].GetUInt8();
             if (icon == REALM_TYPE_FFA_PVP)
                 icon = REALM_TYPE_PVP;
             if (icon >= MAX_CLIENT_REALM_TYPE)
                 icon = REALM_TYPE_NORMAL;
-            RealmFlags flag = ConvertLegacyRealmFlags(Trinity::Legacy::RealmFlags(fields[6].GetUInt8()));
-            uint8 timezone = fields[7].GetUInt8();
-            uint8 allowedSecurityLevel = fields[8].GetUInt8();
-            RealmPopulationState pop = ConvertLegacyPopulationState(Trinity::Legacy::RealmFlags(fields[6].GetUInt8()), fields[9].GetFloat());
-            uint32 build = fields[10].GetUInt32();
-            uint8 region = fields[11].GetUInt8();
-            uint8 battlegroup = fields[12].GetUInt8();
+            RealmFlags flag = ConvertLegacyRealmFlags(Trinity::Legacy::RealmFlags(fields[8].GetUInt8()));
+            uint8 timezone = fields[9].GetUInt8();
+            uint8 allowedSecurityLevel = fields[10].GetUInt8();
+            RealmPopulationState pop = ConvertLegacyPopulationState(Trinity::Legacy::RealmFlags(fields[8].GetUInt8()), fields[11].GetFloat());
+            uint32 build = fields[12].GetUInt32();
+            uint8 region = fields[13].GetUInt8();
+            uint8 battlegroup = fields[14].GetUInt8();
 
             Battlenet::RealmHandle id{ region, battlegroup, realmId };
 
-            UpdateRealm(*newRealms.try_emplace(id, std::make_shared<Realm>()).first->second, id, build, name, externalAddress->address(), localAddress->address(), port, icon,
+            UpdateRealm(*newRealms.try_emplace(id, std::make_shared<Realm>()).first->second, id, build, name, std::move(addresses), port, icon,
                 flag, timezone, (allowedSecurityLevel <= SEC_ADMINISTRATOR ? AccountTypes(allowedSecurityLevel) : SEC_ADMINISTRATOR), pop);
 
             newSubRegions.insert(Battlenet::RealmHandle{ region, battlegroup, 0 }.GetAddressString());
 
+            auto buildAddressesLogText = [&]
+            {
+                std::string text;
+                for (boost::asio::ip::address const& address : newRealms[id]->Addresses)
+                {
+                    text += address.to_string();
+                    text += ' ';
+                }
+                return text;
+            };
+
             if (!existingRealms.erase(id))
-                TC_LOG_INFO("realmlist", "Added realm \"{}\" at {}:{}.", name, externalAddressString, port);
+                TC_LOG_INFO("realmlist", "Added realm \"{}\" at {}(port {}).", name, buildAddressesLogText(), port);
             else
-                TC_LOG_DEBUG("realmlist", "Updating realm \"{}\" at {}:{}.", name, externalAddressString, port);
+                TC_LOG_DEBUG("realmlist", "Updating realm \"{}\" at {}(port {}).", name, buildAddressesLogText(), port);
         }
         while (result->NextRow());
     }
@@ -322,12 +337,14 @@ uint32 RealmList::JoinRealm(uint32 realmAddress, uint32 build, ClientBuild::Vari
         if (realm->PopulationLevel == RealmPopulationState::Offline || realm->Build != build || accountSecurityLevel < realm->AllowedSecurityLevel)
             return ERROR_USER_SERVER_NOT_PERMITTED_ON_REALM;
 
+        boost::asio::ip::address addressForClient = realm->GetAddressForClient(clientAddress);
+
         JSON::RealmList::RealmListServerIPAddresses serverAddresses;
         JSON::RealmList::RealmIPAddressFamily* addressFamily = serverAddresses.add_families();
-        addressFamily->set_family(1);
+        addressFamily->set_family(addressForClient.is_v6() ? 2 : 1);
 
         JSON::RealmList::IPAddress* address = addressFamily->add_addresses();
-        address->set_ip(realm->GetAddressForClient(clientAddress).to_string());
+        address->set_ip(addressForClient.to_string());
         address->set_port(realm->Port);
 
         std::string json = "JSONRealmListServerIPAddresses:" + JSON::Serialize(serverAddresses);
diff --git a/src/server/shared/Realm/RealmList.h b/src/server/shared/Realm/RealmList.h
index 4ece6124a51..ddb42ae7e1f 100644
--- a/src/server/shared/Realm/RealmList.h
+++ b/src/server/shared/Realm/RealmList.h
@@ -76,7 +76,7 @@ private:
 
     void UpdateRealms();
     static void UpdateRealm(Realm& realm, Battlenet::RealmHandle const& id, uint32 build, std::string const& name,
-        boost::asio::ip::address&& address, boost::asio::ip::address&& localAddr,
+        std::vector<boost::asio::ip::address>&& addresses,
         uint16 port, uint8 icon, RealmFlags flag, uint8 timezone, AccountTypes allowedSecurityLevel, RealmPopulationState population);
     void FillRealmEntry(Realm const& realm, uint32 clientBuild, AccountTypes accountSecurityLevel, JSON::RealmList::RealmEntry* realmEntry) const;
 
diff --git a/src/server/worldserver/worldserver.conf.dist b/src/server/worldserver/worldserver.conf.dist
index c45113097c2..46c3bf6bc7f 100644
--- a/src/server/worldserver/worldserver.conf.dist
+++ b/src/server/worldserver/worldserver.conf.dist
@@ -176,6 +176,7 @@ InstanceServerPort = 8086
 #
 #    BindIP
 #        Description: Bind world server to IP/hostname.
+#                     Using IPv6 address (such as "::") will enable both IPv4 and IPv6 connections
 #        Default:     "0.0.0.0" - (Bind to all IPs on the system)
 
 BindIP = "0.0.0.0"