Add new API function cgi_redirect_status() and deprecate old one

Sending a HTTP Location header only makes sense with certain HTTP status
responses [1]. For letting a CGI return a certain status code, you have
to send the pseudo header 'Status:' with the right code, the webserver
will remove that and send the corresponding HTTP status instead. See RFC
3875 section 6.3.3 [2] for details.

The new API function allows to send a 'redirect' header 'Location:'
together with an arbitrary status code. The old API function is marked
deprecated, because it makes no sense sending 'Location' without
'Status' or the standard response code 200.

[1] https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Location
[2] https://tools.ietf.org/html/rfc3875#section-6.3.3

Signed-off-by: Alexander Dahl <[email protected]>

include/libcgi/cgi.h

@@ -34,6 +34,58 @@
 #define CGI_DEPRECATED
 #endif
 
+/**
+ *	HTTP status codes.
+ *
+ *	@see	http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html
+ */
+enum cgi_http_status_code {
+	HTTP_STATUS_CONTINUE			= 100,
+	HTTP_STATUS_SWITCHING_PROTOCOLS	= 101,
+
+	HTTP_STATUS_OK					= 200,
+	HTTP_STATUS_CREATED				= 201,
+	HTTP_STATUS_ACCEPTED			= 202,
+	HTTP_STATUS_NON_AUTH_INFO		= 203,
+	HTTP_STATUS_NO_CONTENT			= 204,
+	HTTP_STATUS_RESET_CONTENT		= 205,
+	HTTP_STATUS_PARTIAL_CONTENT		= 206,
+
+	HTTP_STATUS_MULTIPLE_CHOICES	= 300,
+	HTTP_STATUS_MOVED_PERMANENTLY	= 301,
+	HTTP_STATUS_FOUND				= 302,
+	HTTP_STATUS_SEE_OTHER			= 303,
+	HTTP_STATUS_NOT_MODIFIED		= 304,
+	HTTP_STATUS_USE_PROXY			= 305,
+	HTTP_STATUS_TEMPORARY_REDIRECT	= 307,
+
+	HTTP_STATUS_BAD_REQUEST			= 400,
+	HTTP_STATUS_UNAUTHORIZED		= 401,
+	HTTP_STATUS_PAYMENT_REQUIRED	= 402,
+	HTTP_STATUS_FORBIDDEN			= 403,
+	HTTP_STATUS_NOT_FOUND			= 404,
+	HTTP_STATUS_METHOD_NOT_ALLOWED	= 405,
+	HTTP_STATUS_NOT_ACCEPTABLE		= 406,
+	HTTP_STATUS_PROXY_AUTH_REQUIRED	= 407,
+	HTTP_STATUS_REQUEST_TIMEOUT		= 408,
+	HTTP_STATUS_CONFLICT			= 409,
+	HTTP_STATUS_GONE				= 410,
+	HTTP_STATUS_LENGTH_REQUIRED		= 411,
+	HTTP_STATUS_PRECONDITION_FAILED	= 412,
+	HTTP_STATUS_REQ_ENT_TOO_LARGE	= 413,
+	HTTP_STATUS_REQ_URI_TOO_LONG	= 414,
+	HTTP_STATUS_UNSUPP_MEDIA_TYPE	= 415,
+	HTTP_STATUS_REQ_RANGE_NOT_SATIS	= 416,
+	HTTP_STATUS_EXPECTATION_FAILED	= 417,
+
+	HTTP_STATUS_INTERNAL_SERVER_ERR	= 500,
+	HTTP_STATUS_NOT_IMPLEMENTED		= 501,
+	HTTP_STATUS_BAD_GATEWAY			= 502,
+	HTTP_STATUS_SERVICE_UNAVAILABLE	= 503,
+	HTTP_STATUS_GATEWAY_TIMEOUT		= 504,
+	HTTP_STATUS_HTTP_VER_NOT_SUPP	= 505,
+};
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -57,7 +109,7 @@ extern int cgi_display_errors;
 
 // General purpose cgi functions
 extern void cgi_init_headers(void);
-extern void cgi_redirect(char *url);
+CGI_DEPRECATED void cgi_redirect(char *url);
 extern void cgi_fatal(const char *error);
 extern char *cgi_unescape_special_chars(const char *str);
 extern char *cgi_escape_special_chars(const char *str);
@@ -143,6 +195,20 @@ void cgi_session_free( void );
  */
 const char *cgi_version( void );
 
+/**
+ *	Send a HTTP header 'Location:' with the uri provided together with a
+ *	pseudo header 'Status:' with some HTTP status code. See RFC 3875,
+ *	section 6.3 (Response Header Fields) for details on how this is
+ *	supposed to work.
+ *
+ *	@see	https://tools.ietf.org/html/rfc3875#section-6.3
+ *
+ *	@param[in]	status_code	HTTP status code number, pick it from our enum type
+ *	@param[in]	uri			URI to be sent with the Location: header
+ */
+void cgi_redirect_status( enum cgi_http_status_code status_code,
+		const char *uri );
+
 #ifdef __cplusplus
 }
 #endif

src/cgi.c

@@ -557,6 +557,22 @@ const char *cgi_version( void )
 	return CGI_VERSION;
 }
 
+void cgi_redirect_status( enum cgi_http_status_code status_code,
+		const char *uri )
+{
+	if ( headers_initialized )
+	{
+		libcgi_error( E_WARNING,
+				"<br><b>Cannot redirect. Headers already sent</b><br>" );
+		return;
+	}
+
+	printf( "Status: %i\r\n"
+			"Location: %s\r\n"
+			"\r\n",
+			status_code, uri );
+}
+
 /**
 * @}
 */