Implement plugin loading

Author: cbdevnet

makefile

@@ -1,7 +1,7 @@
 PLUGINPATH=plugins/
 
 CFLAGS=-g -Wall -Wpedantic -DPLUGINS=\"$(PLUGINPATH)\"
-LDLIBS=-lnettle
+LDLIBS=-lnettle -ldl
 
 OBJECTS=builtins.o network.o websocket.o plugin.o
 

network.c

@@ -127,13 +127,13 @@ int network_socket_unix(char* path, int socktype, int listener){
 	if(listener){
 		unlink(path);
 		if(bind(fd, (struct sockaddr*) &addr, sizeof(addr))){
-			fprintf(stderr, "Failed to bind: %s\n", strerror(errno));
+			fprintf(stderr, "Failed to bind %s: %s\n", path, strerror(errno));
 			close(fd);
 			return -1;
 		}
 
 		if(listen(fd, SOMAXCONN)){
-			fprintf(stderr, "Failed to listen: %s\n", strerror(errno));
+			fprintf(stderr, "Failed to listen on %s: %s\n", path, strerror(errno));
 			close(fd);
 			return -1;
 		}
@@ -143,7 +143,7 @@ int network_socket_unix(char* path, int socktype, int listener){
 
 	//connect clients
 	if(connect(fd, (struct sockaddr*) &addr, sizeof(addr))){
-		fprintf(stderr, "Failed to connect: %s\n", strerror(errno));
+		fprintf(stderr, "Failed to connect to %s: %s\n", path, strerror(errno));
 		close(fd);
 		return -1;
 	}

plugin.c

@@ -1,20 +1,112 @@
 #include <string.h>
 #include <stdio.h>
+#include <sys/types.h>
+#include <dirent.h>
+#include <errno.h>
+#include <dlfcn.h>
 
 #include "websocksy.h"
 #include "plugin.h"
 
+//cheap out because i dont want the overhead of allocating here
+#define MAX_PLUGIN_PATH 4096
+
 static size_t framing_functions = 0;
 static ws_framing* framing_function = NULL;
 static char** framing_function_name = NULL;
 
+static size_t attached_libraries = 0;
+static void** attached_library = NULL;
+
+static void* plugin_attach(char* path){
+	void* module = dlopen(path, RTLD_LAZY);
+
+	if(!module){
+		fprintf(stderr, "Failed to load module %s\n", dlerror());
+		return NULL;
+	}
+
+	attached_library = realloc(attached_library, (attached_libraries + 1) * sizeof(void*));
+	if(!attached_library){
+		fprintf(stderr, "Failed to allocate memory\n");
+		dlclose(module);
+		return NULL;
+	}
+
+	attached_library[attached_libraries] = module;
+	attached_libraries++;
+
+	return module;
+}
+
 int plugin_framing_load(char* path){
-	//TODO load plugins
+	DIR* directory = opendir(path);
+	struct dirent* file = NULL;
+	char plugin_path[MAX_PLUGIN_PATH] = "";
+	size_t path_len;
+
+	if(strlen(path) >= sizeof(plugin_path) - 20){
+		fprintf(stderr, "Plugin path length exceeds limit\n");
+		return 1;
+	}
+
+	strncpy(plugin_path, path, sizeof(plugin_path) - 2);
+	if(path[strlen(path) - 1] != '/'){
+		plugin_path[strlen(path)] = '/';
+		plugin_path[strlen(path) + 1] = 0;
+	}
+	path_len = strlen(plugin_path);
+
+	if(!directory){
+		fprintf(stderr, "Failed to open directory %s: %s\n", path, strerror(errno));
+		return 0;
+	}
+
+	for(file = readdir(directory); file; file = readdir(directory)){
+		//skip backends
+		if(!strncmp(file->d_name, "backend_", 8)){
+			continue;
+		}
+		//skip file not ending in .so
+		if(strlen(file->d_name) < 4 || strcmp(file->d_name + strlen(file->d_name) - 3, ".so")){
+			continue;
+		}
+		strncpy(plugin_path + path_len, file->d_name, sizeof(plugin_path) - path_len - 2);
+		if(!plugin_attach(plugin_path)){
+			return 1;
+		}
+	}
+
+	closedir(directory);
 	return 0;
 }
 
-int plugin_backend_load(char* backend_requested, ws_backend* backend){
-	//TODO load backend
+int plugin_backend_load(char* path, char* backend_requested, ws_backend* backend){
+	char plugin_path[MAX_PLUGIN_PATH] = "";
+	void* handle = NULL;
+
+	if(strlen(path) >= sizeof(plugin_path) - 30){
+		fprintf(stderr, "Plugin path length exceeds limit\n");
+		return 1;
+	}
+
+	snprintf(plugin_path, sizeof(plugin_path), "%s%sbackend_%s.so", path, (path[strlen(path) - 1] == '/') ? "" : "/", backend_requested);
+
+	handle = plugin_attach(plugin_path);
+	if(!handle){
+		return 1;
+	}
+
+	//read backend functions into the structure
+	backend->init = (ws_backend_init) dlsym(handle, "init");
+	backend->config = (ws_backend_configure) dlsym(handle, "configure");
+	backend->query = (ws_backend_query) dlsym(handle, "query");
+	backend->cleanup = (ws_backend_cleanup) dlsym(handle, "cleanup");
+
+	if(!backend->init || !backend->query){
+		fprintf(stderr, "Backend module %s is missing required symbols\n", plugin_path);
+		return 1;
+	}
 	return 0;
 }
 
@@ -63,8 +155,8 @@ ws_framing plugin_framing(char* name){
 
 void plugin_cleanup(){
 	size_t u;
-	//TODO dlclose all plugins
-
+	
+	//free allocated buffers
 	for(u = 0; u < framing_functions; u++){
 		free(framing_function_name[u]);
 	}
@@ -74,4 +166,11 @@ void plugin_cleanup(){
 	framing_function_name = 0;
 	framing_function = NULL;
 	framing_functions = 0;
+
+	//dlclose all plugins
+	for(u = 0; u < attached_libraries; u++){
+		dlclose(attached_library[u]);
+	}
+	free(attached_library);
+	attached_libraries = 0;
 }

plugin.h

@@ -1,6 +1,6 @@
 /* Shared object handling */
 int plugin_framing_load(char* path);
-int plugin_backend_load(char* backend_requested, ws_backend* backend);
+int plugin_backend_load(char* path, char* backend_requested, ws_backend* backend);
 
 /* Framing function registry */
 int plugin_register_framing(char* name, ws_framing func);

websocket.c

@@ -66,8 +66,9 @@ int ws_close(websocket* ws, ws_close_reason code, char* reason){
 	for(p = 0; p < ws->protocols; p++){
 		free(ws->protocol[p]);
 	}
-	ws->protocols = 0;
+	free(ws->protocol);
 	ws->protocol = NULL;
+	ws->protocols = 0;
 
 	ws->read_buffer_offset = 0;
 	ws->peer_buffer_offset = 0;

websocksy.c

@@ -21,7 +21,8 @@
 
 /* TODO
  * - TLS
- * - framing function discovery / registry
+ * - plugin loading
+ * - config file
  * - WS p2p
  */
 
@@ -111,8 +112,8 @@ static peer_transport client_detect_transport(char* host){
 		memmove(host, host + 9, strlen(host) - 8);
 		return peer_fifo_rx;
 	}
-	else if(!strncmp(host, "unix://", 8)){
-		memmove(host, host + 8, strlen(host) - 7);
+	else if(!strncmp(host, "unix://", 7)){
+		memmove(host, host + 7, strlen(host) - 6);
 		return peer_unix_stream;
 	}
 	else if(!strncmp(host, "unix-dgram://", 13)){
@@ -213,7 +214,7 @@ static int args_parse(int argc, char** argv){
 					config.backend.cleanup();
 				}
 				//load the backend plugin
-				if(plugin_backend_load(argv[u + 1], &(config.backend))){
+				if(plugin_backend_load(PLUGINS, argv[u + 1], &(config.backend))){
 					return 1;
 				}
 				if(config.backend.init() != WEBSOCKSY_API_VERSION){

websocksy.h

@@ -153,7 +153,7 @@ typedef struct /*_web_socket*/ {
  * sheer guesses).
  *
  * Backends are supplied as shared objects exporting the following symbols:
- * 	* `init`: Optional, initialize any storage or connections required
+ * 	* `init`: Required, initialize any storage or connections required
  * 	* `configure`: Optional, configure the backend
  * 	* `query`: Required, find a peer for the given parameters
  * 	* `cleanup`: Optional, Release any acquired resources prior to shutdown