How To Make SSL Requests Using WinInet

MORE INFORMATION

It is possible to establish a Secure Socket Layer (SSL) or Private Communications Technology (PCT) HTTP session with the WinInet APIs. Secure HTTP, denoted as HTTPS://, takes place over TCP port 443. Code similar to the following can be used to establish an HTTPS session:

   ...
   hOpen = InternetOpen (...);
   Connect = InternetConnect (
                hOpen,                      // InternetOpen handle
                "MyHttpServer",             // Server  name
      INTERNET_DEFAULT_HTTPS_PORT,// Default HTTPS port - 443
                "",                         // User name
                "",                         //  User password
                INTERNET_SERVICE_HTTP,      // Service
      0,                          // Flags
      0                           // Context
                   );
   hReq = HttpOpenRequest (
                hConnect,                   // InternetConnect handle
      "GET",                      // Method
      "",                         // Object name
      HTTP_VERSION,               // Version
      "",                         // Referrer
                NULL,                       // Extra headers
      INTERNET_FLAG_SECURE,       // Flags
      0                           // Context
                );
   ...
				

Please note two differences when using HTTPS instead of HTTP:

• InternetConnect uses INTERNET_DEFAULT_HTTPS_PORT instead of INTERNET_INVALID_PORT_NUMBER or INTERNET_DEFAULT_HTTP_PORT
• HttpOpenRequest uses the INTERNET_FLAG_SECURE option in addition to all other options.

The following two options can be used either in HttpOpenRequest or in InternetOpenUrl to ignore invalid certificate errors:

• INTERNET_FLAG_IGNORE_CERT_CN_INVALID - Ignores errors that can be caused by the certificate host name of the server not matching the host name in the request.
• INTERNET_FLAG_IGNORE_CERT_DATE_INVALID - Ignores errors that can be caused by an expired server certificate.

Please see the Internet Client SDK documentation for more information on these flags.

SSL and PCT functionality are provided by Schannel.dll, which is properly installed when you run the redistribution program Wintdist.exe or Wint351.exe. See Redist.txt or Axredist.txt for information about redistributing Schannel.dll.