add native csrf helpers

src/lib/uri.cpp

@@ -877,6 +877,39 @@ void session_destroy(String session_name)
 	}
 }
 
+String csrf_session_key(String token_name)
+{
+	token_name = first(trim(token_name), "csrf_token");
+	return("_csrf_" + token_name);
+}
+
+String csrf_token(String session_name, String token_name)
+{
+	session_start(session_name);
+	String key = csrf_session_key(token_name);
+	if(context->session[key] == "")
+	{
+		String random = random_bytes(32);
+		if(random.size() != 32)
+			random = session_id_create();
+		context->session[key] = sha256_hex(random);
+	}
+	return(context->session[key]);
+}
+
+bool csrf_valid(String submitted_token, String session_name, String token_name)
+{
+	session_start(session_name);
+	String expected = context->session[csrf_session_key(token_name)];
+	return(expected != "" && submitted_token != "" && crypto_equal(submitted_token, expected));
+}
+
+void csrf_rotate(String session_name, String token_name)
+{
+	session_start(session_name);
+	context->session.erase(csrf_session_key(token_name));
+}
+
 String ws_make_accept_key(String client_key)
 {
 	return(base64_encode(gen_sha1(

src/lib/uri.h

@@ -33,6 +33,9 @@ StringMap load_session_data(String session_id);
 void save_session_data(String session_id, StringMap data);
 String session_start(String session_name = "uce-session");
 void session_destroy(String session_name = "uce-session");
+String csrf_token(String session_name = "uce-session", String token_name = "csrf_token");
+bool csrf_valid(String submitted_token, String session_name = "uce-session", String token_name = "csrf_token");
+void csrf_rotate(String session_name = "uce-session", String token_name = "csrf_token");
 String ws_make_accept_key(String client_key);
 bool ws_is_valid_client_key(String client_key);
 String ws_encode_frame(String payload, u8 opcode = 0x1, bool is_final_fragment = true);