pass session certificate for showCertificate()

src/Functions/FunctionShowCertificate.h

@@ -1,5 +1,7 @@
 #pragma once
 
+#include <memory>
+#include <string>
 #include <Common/config.h>
 
 #include <Columns/ColumnMap.h>
@@ -33,14 +35,18 @@ class FunctionShowCertificate : public IFunction
 public:
     static constexpr auto name = "showCertificate";
 
-    static FunctionPtr create(ContextPtr)
+    static FunctionPtr create(ContextPtr ctx)
     {
 #if !defined(USE_SSL) || USE_SSL == 0
         throw Exception(ErrorCodes::SUPPORT_IS_DISABLED, "SSL support is disabled");
 #endif
-        return std::make_shared<FunctionShowCertificate>();
+        return std::make_shared<FunctionShowCertificate>(ctx->getQueryContext()->getClientInfo().certificate);
     }
 
+    std::string certificate;
+
+    explicit FunctionShowCertificate(const std::string & certificate_ = "") : certificate(certificate_) {}
+
     String getName() const override { return name; }
 
     size_t getNumberOfArguments() const override { return 0; }
@@ -61,7 +67,15 @@ public:
         if (input_rows_count)
         {
 #if USE_SSL
-            if (const X509 * cert = SSL_CTX_get0_certificate(Poco::Net::SSLManager::instance().defaultServerContext()->sslContext()))
+            std::unique_ptr<Poco::Crypto::X509Certificate> x509_cert;
+            if (!certificate.empty())
+                x509_cert = std::make_unique<Poco::Crypto::X509Certificate>(certificate);
+
+            const X509 * cert = x509_cert ?
+                x509_cert->certificate() :
+                SSL_CTX_get0_certificate(Poco::Net::SSLManager::instance().defaultServerContext()->sslContext());
+
+            if (cert)
             {
                 BIO * b = BIO_new(BIO_s_mem());
                 SCOPE_EXIT(

src/Interpreters/ClientInfo.h

@@ -69,6 +69,7 @@ public:
 
     Interface interface = Interface::TCP;
     bool is_secure = false;
+    String certificate;
 
     /// For tcp
     String os_user;

src/Interpreters/Session.cpp

@@ -244,7 +244,7 @@ void Session::shutdownNamedSessions()
     NamedSessionsStorage::instance().shutdown();
 }
 
-Session::Session(const ContextPtr & global_context_, ClientInfo::Interface interface_, bool is_secure)
+Session::Session(const ContextPtr & global_context_, ClientInfo::Interface interface_, bool is_secure, const std::string & certificate)
     : auth_id(UUIDHelpers::generateV4()),
       global_context(global_context_),
       log(&Poco::Logger::get(String{magic_enum::enum_name(interface_)} + "-Session"))
@@ -252,6 +252,7 @@ Session::Session(const ContextPtr & global_context_, ClientInfo::Interface inter
     prepared_client_info.emplace();
     prepared_client_info->interface = interface_;
     prepared_client_info->is_secure = is_secure;
+    prepared_client_info->certificate = certificate;
 }
 
 Session::~Session()

src/Interpreters/Session.h

@@ -32,7 +32,7 @@ public:
     /// Stops using named sessions. The method must be called at the server shutdown.
     static void shutdownNamedSessions();
 
-    Session(const ContextPtr & global_context_, ClientInfo::Interface interface_, bool is_secure = false);
+    Session(const ContextPtr & global_context_, ClientInfo::Interface interface_, bool is_secure = false, const std::string & certificate = "");
     ~Session();
 
     Session(const Session &&) = delete;

src/Server/TCPHandler.cpp

@@ -115,6 +115,7 @@ TCPHandler::TCPHandler(IServer & server_, TCPServer & tcp_server_, const Poco::N
     , tcp_server(tcp_server_)
     , log(&Poco::Logger::get("TCPHandler"))
     , forwarded_for(stack_data.forwarded_for)
+    , certificate(stack_data.certificate)
     , server_display_name(std::move(server_display_name_))
 {
 }
@@ -1065,7 +1066,7 @@ std::unique_ptr<Session> TCPHandler::makeSession()
 {
     auto interface = is_interserver_mode ? ClientInfo::Interface::TCP_INTERSERVER : ClientInfo::Interface::TCP;
 
-    auto res = std::make_unique<Session>(server.context(), interface, socket().secure());
+    auto res = std::make_unique<Session>(server.context(), interface, socket().secure(), certificate);
 
     auto & client_info = res->getClientInfo();
     client_info.forwarded_for = forwarded_for;

src/Server/TCPHandler.h

@@ -153,6 +153,7 @@ private:
     Poco::Logger * log;
 
     String forwarded_for;
+    String certificate;
 
     String client_name;
     UInt64 client_version_major = 0;

src/Server/TCPProtocolStackData.h

@@ -10,6 +10,7 @@ struct TCPProtocolStackData
 {
     Poco::Net::StreamSocket socket;
     std::string forwarded_for;
+    std::string certificate;
 };
 
 }

src/Server/TLSHandler.h

@@ -43,6 +43,7 @@ public:
             ctx = new Context(Context::Usage::SERVER_USE, key, certificate, ctx->getCAPaths().caLocation);
         socket() = SecureStreamSocket::attach(socket(), ctx);
         stack_data.socket = socket();
+        stack_data.certificate = certificate;
 #else
         throw Exception{"SSL support for TCP protocol is disabled because Poco library was built without NetSSL support.",
                         ErrorCodes::SUPPORT_IS_DISABLED};