ncd: modules: add backtrack

generated/blog_channel_ncd_backtrack.h

@@ -0,0 +1,4 @@
+#ifdef BLOG_CURRENT_CHANNEL
+#undef BLOG_CURRENT_CHANNEL
+#endif
+#define BLOG_CURRENT_CHANNEL BLOG_CHANNEL_ncd_backtrack

generated/blog_channels_defines.h

@@ -132,4 +132,5 @@
 #define BLOG_CHANNEL_dostest_attacker 131
 #define BLOG_CHANNEL_ncd_timer 132
 #define BLOG_CHANNEL_ncd_file_open 133
-#define BLOG_NUM_CHANNELS 134
+#define BLOG_CHANNEL_ncd_backtrack 134
+#define BLOG_NUM_CHANNELS 135

generated/blog_channels_list.h

@@ -132,3 +132,4 @@
 {"dostest_attacker", 4},
 {"ncd_timer", 4},
 {"ncd_file_open", 4},
+{"ncd_backtrack", 4},

ncd/CMakeLists.txt

@@ -163,6 +163,7 @@ add_library(ncdinterpreter
     modules/net_ipv6_addr_in_network.c
     modules/timer.c
     modules/file_open.c
+    modules/backtrack.c
     ${NCD_ADDITIONAL_SOURCES}
 )
 target_link_libraries(ncdinterpreter

ncd/modules/backtrack.c

@@ -0,0 +1,106 @@
+/**
+ * @file backtrack.c
+ * @author Ambroz Bizjak <ambrop7@gmail.com>
+ * 
+ * @section LICENSE
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the author nor the
+ *    names of its contributors may be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ * 
+ * @section DESCRIPTION
+ * 
+ * Synopsis:
+ *   backtrack_point()
+ *   backtrack_point::go()
+ * 
+ * Description:
+ *   The backtrack_point() statement creates a backtrack point, going up immedietely.
+ *   The go() method triggers backtracking to the backtrack point, i.e. makes the
+ *   backtrack_point() statement go down and back up at atomically. The go() method
+ *   itself goes up immedietely, but side effects of triggering backtracking have
+ *   priority.
+ */
+
+#include <stddef.h>
+
+#include <ncd/NCDModule.h>
+
+#include <generated/blog_channel_ncd_backtrack.h>
+
+#define ModuleLog(i, ...) NCDModuleInst_Backend_Log((i), BLOG_CURRENT_CHANNEL, __VA_ARGS__)
+
+static void func_new (void *unused, NCDModuleInst *i, const struct NCDModuleInst_new_params *params)
+{
+    // check arguments
+    if (!NCDVal_ListRead(params->args, 0)) {
+        ModuleLog(i, BLOG_ERROR, "wrong arity");
+        goto fail0;
+    }
+    
+    // go up
+    NCDModuleInst_Backend_Up(i);
+    return;
+    
+fail0:
+    NCDModuleInst_Backend_SetError(i);
+    NCDModuleInst_Backend_Dead(i);
+}
+
+static void go_func_new (void *unused, NCDModuleInst *i, const struct NCDModuleInst_new_params *params)
+{
+    // check arguments
+    if (!NCDVal_ListRead(params->args, 0)) {
+        ModuleLog(i, BLOG_ERROR, "wrong arity");
+        goto fail0;
+    }
+    
+    // get backtrack point
+    NCDModuleInst *backtrack_point_inst = params->method_user;
+    
+    // go up (after toggling)
+    NCDModuleInst_Backend_Up(i);
+    
+    // toggle backtrack point
+    NCDModuleInst_Backend_Down(backtrack_point_inst);
+    NCDModuleInst_Backend_Up(backtrack_point_inst);
+    return;
+    
+fail0:
+    NCDModuleInst_Backend_SetError(i);
+    NCDModuleInst_Backend_Dead(i);
+}
+
+static struct NCDModule modules[] = {
+    {
+        .type = "backtrack_point",
+        .func_new2 = func_new
+    }, {
+        .type = "backtrack_point::go",
+        .func_new2 = go_func_new
+    }, {
+        .type = NULL
+    }
+};
+
+const struct NCDModuleGroup ncdmodule_backtrack = {
+    .modules = modules
+};

ncd/modules/modules.h

@@ -76,6 +76,7 @@ extern const struct NCDModuleGroup ncdmodule_net_ipv4_addr_in_network;
 extern const struct NCDModuleGroup ncdmodule_net_ipv6_addr_in_network;
 extern const struct NCDModuleGroup ncdmodule_timer;
 extern const struct NCDModuleGroup ncdmodule_file_open;
+extern const struct NCDModuleGroup ncdmodule_backtrack;
 #ifndef BADVPN_EMSCRIPTEN
 extern const struct NCDModuleGroup ncdmodule_regex_match;
 extern const struct NCDModuleGroup ncdmodule_run;
@@ -155,6 +156,7 @@ static const struct NCDModuleGroup *ncd_modules[] = {
     &ncdmodule_net_ipv6_addr_in_network,
     &ncdmodule_timer,
     &ncdmodule_file_open,
+    &ncdmodule_backtrack,
 #ifndef BADVPN_EMSCRIPTEN
     &ncdmodule_regex_match,
     &ncdmodule_run,