SSL/TLS does not work with DSA server certificates about znc HOT 2 CLOSED

diff --git a/Csocket.cpp b/Csocket.cpp
index b2bcf44..3748018 100644
--- a/Csocket.cpp
+++ b/Csocket.cpp
@@ -36,6 +36,7 @@
 #endif /* __NetBSD__ */

 #ifdef HAVE_LIBSSL
+#include <stdio.h>
 #include <openssl/conf.h>
 #include <openssl/engine.h>
 #endif /* HAVE_LIBSSL */
@@ -1273,6 +1274,35 @@ bool Csock::SSLServerSetup()
        return( false );
    }

+   FILE *dhParamsFile = 0;
+   if ( ! ( dhParamsFile = fopen( m_sPemFile.c_str(), "r" ) ) )
+   {
+       CS_DEBUG( "There is a problem with [" << m_sPemFile << "]" );
+       return( false );
+   }
+
+   DH *dhParams = PEM_read_DHparams( dhParamsFile, 0, 0, 0 );
+   fclose( dhParamsFile );
+   dhParamsFile = 0;
+   if ( dhParams )
+   {
+       SSL_CTX_set_options( m_ssl_ctx, SSL_OP_SINGLE_DH_USE );
+       if ( ! SSL_CTX_set_tmp_dh( m_ssl_ctx, dhParams ) )
+       {
+           CS_DEBUG( "Error setting ephemeral DH parameters from [" << m_sPemFile << "]" );
+           SSLErrors( __FILE__, __LINE__ );
+           DH_free( dhParams );
+           dhParams = 0;
+           return( false );
+       }
+       DH_free( dhParams );
+       dhParams = 0;
+   }
+   else
+   {
+       ERR_clear_error();
+   }
+
    if ( SSL_CTX_set_cipher_list( m_ssl_ctx, m_sCipherType.c_str() ) <= 0 )
    {
        CS_DEBUG( "Could not assign cipher [" << m_sCipherType << "]" );