Delphi如何使用最新版本的OpenSSL

        无论是D6还是D10，要让自带的Indy方便的使用最新版的OpenSSL及其函数，需要客制化文件其头文件的常量定义IdSSLOpenSSLHeaders.pas

        步骤：

        1、官网下载最新版的OpenSSL

        2、修改Indy中的关于OpenSSL的动态库名或静态库名：

        D6版Indy8.0.25，见行次：2632~2634

implementation
//......

const
  SSL_DLL_name = 'ssleay32.dll'; {Do not localize}
  SSLCLIB_DLL_name = 'libeay32.dll'; {Do not localize}

        D10版Indy10.6.2，见行次：19555~19591

implementation
//......

{$IFDEF STATICLOAD_OPENSSL}
const
  SSL_LIB_name         = 'libssl.a'; {Do not Localize}
  SSLCLIB_LIB_name     = 'libcrypto.a'; {Do not Localize}
{$ELSE}
  {$IFDEF UNIX}
const
  {This is a workaround for some Linux distributions and a few other things
  where the symbolic link libbsl.so and libcrypto.so do not exist}
  SSL_DLL_name         = 'libssl'; {Do not localize}
  SSLCLIB_DLL_name     = 'libcrypto'; {Do not localize}
  SSLDLLVers : array [0..10] of string = (
    '.10',
    '.1.0.2','.1.0.1',
                                              
    '.44',              // MacOS LibreSSL forked from which OpenSSL version? Sometimes found ...
    '.43',              // MacOS LibreSSL forked from which OpenSSL version? Sometimes found ...
                                                   
    '.35',              // MacOS LibreSSL forked from OpenSSL version 1.0.1, almost always found
    //
    '.1.0.0','.0.9.9','.0.9.8','.0.9.7','.0.9.6'
  );
  SSLDLLVersChar : array [0..26] of string = ('','a','b','c','d','e','f','g','h','i',
                                                 'j','k','l','m','n','o','p','q','r',
                                                 's','t','u','v','w','x','y','z');
  {$ENDIF}
  {$IFDEF WINDOWS}
const
  SSL_DLL_name         = 'ssleay32.dll';  {Do not localize}
  //The following is a workaround for an alternative name for
  //one of the OpenSSL .DLL's.  If you compile the .DLL's using
  //mingw32, the SSL .dll might be named 'libssl32.dll' instead of
  //ssleay32.dll like you would expect.
  SSL_DLL_name_alt     = 'libssl32.dll';  {Do not localize}
  SSLCLIB_DLL_name     = 'libeay32.dll';  {Do not localize}
  {$ENDIF}
{$ENDIF}

        比如Windows下，修改Indy10.6.2（D10）的头文件IdSSLOpenSSLHeaders.pas，如上改为：

  {$IFDEF WINDOWS}
const
  //SSL_DLL_name         = 'ssleay32.dll';  {Do not localize}//:屏蔽的
  SSL_DLL_name         = 'libssl-1_1.dll';  {Do not localize}//:改的
  //SSL_DLL_name_alt     = 'libssl32.dll';  {Do not localize}//:屏蔽的
  SSLCLIB_DLL_name     = 'libcrypto-1_1';  {Do not localize}//:改的
  {$ENDIF}
{$ENDIF}

        再如Windows下，修改D6的头文件IdSSLOpenSSLHeaders.pas，如上改为：

  {$IFDEF WINDOWS}
const
  //SSL_DLL_name         = 'ssleay32.dll';  {Do not localize}//:屏蔽的
  SSL_DLL_name         = 'libssl-1_1.dll';  {Do not localize}//:改的
  //SSL_DLL_name_alt     = 'libssl32.dll';  {Do not localize}//:屏蔽的
  SSLCLIB_DLL_name     = 'libcrypto-1_1';  {Do not localize}//:改的
  {$ENDIF}
{$ENDIF}

var
  hIdSSL: Integer = 0;
  hIdSSLLib: Integer = 0;

  hIdCrypto: Integer = 0;  //:加的

        3、按照最新的OpenSSL函数的调用说明，可能依赖调用对应的函数：

         比如，可能依赖调用这些函数：

SSL_CTX_new、TLS_client_method、OPENSSL_init_ssl等等

        4、对Indy8.0.25以下版本（对应D6及其以下），其它函数本质类似IdSsl***、ssl_***，其前加了前缀Indy_，可进行更名：

        比如，D6，第2541行次：

  IdSslSetFd: function(s: PSSL; fd: Integer): Integer cdecl = nil;

        可改为：

  Indy_IdSslSetFd: function(s: PSSL; fd: Integer): Integer cdecl = nil;