ncd: add load_module()

blog_channels.txt

@@ -142,3 +142,4 @@ ncd_buffer 4
 ncd_getenv 4
 BThreadSignal 4
 BLockReactor 4
+ncd_load_module 4

generated/blog_channel_ncd_load_module.h

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

generated/blog_channels_defines.h

@@ -142,4 +142,5 @@
 #define BLOG_CHANNEL_ncd_getenv 141
 #define BLOG_CHANNEL_BThreadSignal 142
 #define BLOG_CHANNEL_BLockReactor 143
-#define BLOG_NUM_CHANNELS 144
+#define BLOG_CHANNEL_ncd_load_module 144
+#define BLOG_NUM_CHANNELS 145

generated/blog_channels_list.h

@@ -142,3 +142,4 @@
 {"ncd_getenv", 4},
 {"BThreadSignal", 4},
 {"BLockReactor", 4},
+{"ncd_load_module", 4},

ncd/CMakeLists.txt

@@ -65,10 +65,11 @@ if (NOT EMSCRIPTEN)
         modules/net_ipv6_route.c
         modules/socket.c
         modules/sys_start_process.c
+        modules/load_module.c
     )
     
     list(APPEND NCD_ADDITIONAL_LIBS
-        dhcpclient arpprobe ncdinterfacemonitor ncdrequest udevmonitor badvpn_random
+        dhcpclient arpprobe ncdinterfacemonitor ncdrequest udevmonitor badvpn_random dl
     )
 endif ()
 

ncd/modules/load_module.c

@@ -0,0 +1,313 @@
+/**
+ * @file load_module.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:
+ *   load_module(string name)
+ */
+
+#include <stddef.h>
+#include <limits.h>
+#include <string.h>
+#include <errno.h>
+#include <unistd.h>
+#include <dlfcn.h>
+
+#include <misc/balloc.h>
+#include <misc/concat_strings.h>
+#include <misc/strdup.h>
+#include <misc/offset.h>
+#include <misc/debug.h>
+#include <structure/LinkedList0.h>
+#include <ncd/NCDModule.h>
+
+#include <generated/blog_channel_ncd_load_module.h>
+
+#define ModuleLog(i, ...) NCDModuleInst_Backend_Log((i), BLOG_CURRENT_CHANNEL, __VA_ARGS__)
+#define ModuleGlobal(i) ((i)->m->group->group_state)
+
+struct global {
+    LinkedList0 modules_list;
+};
+
+struct module {
+    char *name;
+    void *lib_handle;
+    int ncdmodule_loaded;
+    LinkedList0Node modules_list_node;
+};
+
+static struct module * find_module (const char *name, struct global *g)
+{
+    for (LinkedList0Node *ln = LinkedList0_GetFirst(&g->modules_list); ln; ln = LinkedList0Node_Next(ln)) {
+        struct module *mod = UPPER_OBJECT(ln, struct module, modules_list_node);
+        if (!strcmp(mod->name, name)) {
+            return mod;
+        }
+    }
+    return NULL;
+}
+
+static struct module * module_init (const char *name, NCDModuleInst *i)
+{
+    struct global *g = ModuleGlobal(i);
+    ASSERT(!find_module(name, g))
+    
+    struct module *mod = BAlloc(sizeof(*mod));
+    if (!mod) {
+        ModuleLog(i, BLOG_ERROR, "BAlloc failed");
+        goto fail0;
+    }
+    
+    mod->name = b_strdup(name);
+    if (!mod->name) {
+        ModuleLog(i, BLOG_ERROR, "b_strdup failed");
+        goto fail1;
+    }
+    
+    mod->lib_handle = NULL;
+    mod->ncdmodule_loaded = 0;
+    LinkedList0_Prepend(&g->modules_list, &mod->modules_list_node);
+    
+    return mod;
+    
+fail1:
+    BFree(mod);
+fail0:
+    return NULL;
+}
+
+static void module_free (struct module *mod, struct global *g)
+{
+    LinkedList0_Remove(&g->modules_list, &mod->modules_list_node);
+    if (mod->lib_handle) {
+        if (dlclose(mod->lib_handle) != 0) {
+            BLog(BLOG_ERROR, "dlclose failed");
+        }
+    }
+    BFree(mod->name);
+    BFree(mod);
+}
+
+static char * x_read_link (const char *path)
+{
+    size_t size = 32;
+    char *buf = BAlloc(size + 1);
+    if (!buf) {
+        goto fail0;
+    }
+    
+    ssize_t link_size;
+    while (1) {
+        link_size = readlink(path, buf, size);
+        if (link_size < 0) {
+            goto fail1;
+        }
+        if (link_size >= 0 && link_size < size) {
+            break;
+        }
+        if (size > SIZE_MAX / 2 || 2 * size > SIZE_MAX - 1) {
+            goto fail1;
+        }
+        size *= 2;
+        char *new_buf = BRealloc(buf, size + 1);
+        if (!new_buf) {
+            goto fail1;
+        }
+        buf = new_buf;
+    }
+    
+    buf[link_size] = '\0';
+    return buf;
+    
+fail1:
+    BFree(buf);
+fail0:
+    return NULL;
+}
+
+static char * find_module_library (NCDModuleInst *i, const char *module_name)
+{
+    char *ret = NULL;
+    
+    char *self = x_read_link("/proc/self/exe");
+    if (!self) {
+        ModuleLog(i, BLOG_ERROR, "failed to read /proc/self/exe");
+        goto fail0;
+    }
+    
+    char *slash = strrchr(self, '/');
+    if (!slash) {
+        ModuleLog(i, BLOG_ERROR, "contents of /proc/self/exe do not have a slash");
+        goto fail1;
+    }
+    *slash = '\0';
+    
+    const char *paths[] = {"../lib/badvpn-ncd", "../mcvpn", NULL};
+    
+    size_t j;
+    for (j = 0; paths[j]; j++) {
+        char *module_path = concat_strings(6, self, "/", paths[j], "/libncdmodule_", module_name, ".so");
+        if (!module_path) {
+            ModuleLog(i, BLOG_ERROR, "concat_strings failed");
+            goto fail1;
+        }
+        
+        if (access(module_path, F_OK) == 0) {
+            ret = module_path;
+            break;
+        }
+        
+        BFree(module_path);
+    }
+    
+    if (!paths[j]) {
+        ModuleLog(i, BLOG_ERROR, "failed to find module");
+    }
+    
+fail1:
+    BFree(self);
+fail0:
+    return ret;
+}
+
+static int func_globalinit (struct NCDInterpModuleGroup *group, const struct NCDModuleInst_iparams *params)
+{
+    struct global *g = BAlloc(sizeof(*g));
+    if (!g) {
+        BLog(BLOG_ERROR, "BAlloc failed");
+        return 0;
+    }
+    
+    group->group_state = g;
+    LinkedList0_Init(&g->modules_list);
+    
+    return 1;
+}
+
+static void func_globalfree (struct NCDInterpModuleGroup *group)
+{
+    struct global *g = group->group_state;
+    
+    LinkedList0Node *ln;
+    while ((ln = LinkedList0_GetFirst(&g->modules_list))) {
+        struct module *mod = UPPER_OBJECT(ln, struct module, modules_list_node);
+        module_free(mod, g);
+    }
+    
+    BFree(g);
+}
+
+static void func_new (void *unused, NCDModuleInst *i, const struct NCDModuleInst_new_params *params)
+{
+    // check arguments
+    NCDValRef name_arg;
+    if (!NCDVal_ListRead(params->args, 1, &name_arg)) {
+        ModuleLog(i, BLOG_ERROR, "wrong arity");
+        goto fail0;
+    }
+    if (!NCDVal_IsStringNoNulls(name_arg)) {
+        ModuleLog(i, BLOG_ERROR, "wrong type");
+        goto fail0;
+    }
+    
+    struct module *mod = find_module(NCDVal_StringData(name_arg), ModuleGlobal(i));
+    ASSERT(!mod || mod->lib_handle)
+    
+    if (!mod) {
+        mod = module_init(NCDVal_StringData(name_arg), i);
+        if (!mod) {
+            ModuleLog(i, BLOG_ERROR, "module_init failed");
+            goto fail0;
+        }
+        
+        // find module library
+        char *module_path = find_module_library(i, NCDVal_StringData(name_arg));
+        if (!module_path) {
+            module_free(mod, ModuleGlobal(i));
+            goto fail0;
+        }
+        
+        // load it as a dynamic library
+        mod->lib_handle = dlopen(module_path, RTLD_NOW);
+        BFree(module_path);
+        if (!mod->lib_handle) {
+            ModuleLog(i, BLOG_ERROR, "dlopen failed");
+            module_free(mod, ModuleGlobal(i));
+            goto fail0;
+        }
+    }
+    
+    if (!mod->ncdmodule_loaded) {
+        // build name of NCDModuleGroup structure symbol
+        char *group_symbol = concat_strings(2, "ncdmodule_", NCDVal_StringData(name_arg));
+        if (!group_symbol) {
+            ModuleLog(i, BLOG_ERROR, "concat_strings failed");
+            goto fail0;
+        }
+        
+        // resolve NCDModuleGroup structure symbol
+        void *group = dlsym(mod->lib_handle, group_symbol);
+        BFree(group_symbol);
+        if (!group) {
+            ModuleLog(i, BLOG_ERROR, "dlsym failed");
+            goto fail0;
+        }
+        
+        // load module group
+        if (!NCDModuleInst_Backend_InterpLoadGroup(i, (struct NCDModuleGroup *)group)) {
+            ModuleLog(i, BLOG_ERROR, "NCDModuleInst_Backend_InterpLoadGroup failed");
+            goto fail0;
+        }
+        
+        mod->ncdmodule_loaded = 1;
+    }
+    
+    // signal up
+    NCDModuleInst_Backend_Up(i);
+    return;
+    
+fail0:
+    NCDModuleInst_Backend_DeadError(i);
+}
+
+static struct NCDModule modules[] = {
+    {
+        .type = "load_module",
+        .func_new2 = func_new
+    }, {
+        .type = NULL
+    }
+};
+
+const struct NCDModuleGroup ncdmodule_load_module = {
+    .func_globalinit = func_globalinit,
+    .func_globalfree = func_globalfree,
+    .modules = modules
+};

ncd/modules/modules.h

@@ -116,6 +116,7 @@ extern const struct NCDModuleGroup ncdmodule_net_ipv6_addr;
 extern const struct NCDModuleGroup ncdmodule_net_ipv6_route;
 extern const struct NCDModuleGroup ncdmodule_socket;
 extern const struct NCDModuleGroup ncdmodule_sys_start_process;
+extern const struct NCDModuleGroup ncdmodule_load_module;
 #endif
 
 static const struct NCDModuleGroup *ncd_modules[] = {
@@ -201,6 +202,7 @@ static const struct NCDModuleGroup *ncd_modules[] = {
     &ncdmodule_net_ipv6_route,
     &ncdmodule_socket,
     &ncdmodule_sys_start_process,
+    &ncdmodule_load_module,
 #endif
     NULL
 };