X-Git-Url: http://git.lttng.org/?p=ust.git;a=blobdiff_plain;f=libustcomm%2Fustcomm.c;h=f2b7a03b9ea67f8daee033099d0dc2faea9ead1b;hp=6047b6012bc5f5abb98c45c2e28a4038b6b438a6;hb=7032c7d350bfa093db533713df8a14df37360bdc;hpb=688760ef257bee85e3841e0d27ecf4e2f921ef00

diff --git a/libustcomm/ustcomm.c b/libustcomm/ustcomm.c
index 6047b60..f2b7a03 100644
--- a/libustcomm/ustcomm.c
+++ b/libustcomm/ustcomm.c
@@ -1,3 +1,22 @@
+/* Copyright (C) 2009  Pierre-Marc Fournier
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
+ */
+
+/* API used by UST components to communicate with each other via sockets. */
+
 #define _GNU_SOURCE
 #include <sys/types.h>
 #include <signal.h>
@@ -6,6 +25,7 @@
 #include <sys/un.h>
 #include <unistd.h>
 #include <poll.h>
+#include <sys/stat.h>
 
 #include <stdio.h>
 #include <stdlib.h>
@@ -13,195 +33,258 @@
 #include <execinfo.h>
 
 #include "ustcomm.h"
-#include "localerr.h"
+#include "usterr.h"
+#include "share.h"
+#include "multipoll.h"
 
 #define UNIX_PATH_MAX 108
-#define SOCK_DIR "/tmp/socks"
-#define UST_SIGNAL SIGIO
 
-#define MSG_MAX 1000
-
-/* FIXME: ustcomm blocks on message sending, which might be problematic in
- * some cases. Fix the poll() usage so sends are buffered until they don't
- * block.
- */
-
-//static void bt(void)
-//{
-//	void *buffer[100];
-//	int result;
-//
-//	result = backtrace(&buffer, 100);
-//	backtrace_symbols_fd(buffer, result, STDERR_FILENO);
-//}
-
-char *strdup_malloc(const char *s)
+static int mkdir_p(const char *path, mode_t mode)
 {
-	char *retval;
+	const char *path_p;
+	char *tmp;
+
+	int retval = 0;
+	int result;
+	mode_t old_umask;
 
-	if(s == NULL)
-		return NULL;
+	tmp = zmalloc(strlen(path) + 1);
+	if (tmp == NULL)
+		return -1;
 
-	retval = (char *) malloc(strlen(s)+1);
+	/* skip first / */
+	path_p = path+1;
 
-	strcpy(retval, s);
+	old_umask = umask(0);
+	for(;;) {
+		while (*path_p != '/') {
+			if(*path_p == 0)
+				break;
+			++path_p;
+		}
+		if (*path_p == '/') {
+			strncpy(tmp, path, path_p - path);
+			tmp[path_p-path] = '\0';
+			if (tmp[path_p - path - 1] != '/') {
+				result = mkdir(tmp, mode);
+				if(result == -1) {
+					if (!(errno == EEXIST || errno == EACCES || errno == EROFS)) {
+						/* Then this is a real error */
+						retval = -1;
+						break;
+					}
+				}
+			}
+			/* pass / */
+			path_p++;
+		} else {
+			/* last component */
+			result = mkdir(path, mode);
+			if (result == -1)
+				retval = -1;
+			break;
+		}
+	}
 
+	free(tmp);
+	umask(old_umask);
 	return retval;
 }
 
-static void signal_process(pid_t pid)
+static int signal_process(pid_t pid)
 {
-	int result;
+	return 0;
+}
 
-	result = kill(pid, UST_SIGNAL);
-	if(result == -1) {
-		PERROR("kill");
-		return;
-	}
+void ustcomm_init_connection(struct ustcomm_connection *conn)
+{
+	conn->recv_buf = NULL;
+	conn->recv_buf_size = 0;
+	conn->recv_buf_alloc = 0;
+}
 
-	sleep(1);
+int pid_is_online(pid_t pid) {
+	return 1;
 }
 
-int send_message_fd(int fd, const char *msg, char **reply)
+/* Send a message
+ *
+ * @fd: file descriptor to send to
+ * @msg: a null-terminated string containing the message to send
+ *
+ * Return value:
+ * -1: error
+ * 0: connection closed
+ * 1: success
+ */
+
+static int send_message_fd(int fd, const char *msg)
 {
 	int result;
 
-	result = send(fd, msg, strlen(msg), 0);
-	if(result == -1) {
-		PERROR("send");
-		return -1;
-	}
-	else if(result == 0) {
-		return 0;
-	}
-
-	if(!reply)
-		return 1;
-
-	*reply = (char *) malloc(MSG_MAX+1);
-	result = recv(fd, *reply, MSG_MAX, 0);
+	/* Send including the final \0 */
+	result = patient_send(fd, msg, strlen(msg)+1, MSG_NOSIGNAL);
 	if(result == -1) {
-		PERROR("recv");
+		if(errno != EPIPE)
+			PERROR("send");
 		return -1;
 	}
 	else if(result == 0) {
 		return 0;
 	}
-	
-	(*reply)[result] = '\0';
 
+	DBG("sent message \"%s\"", msg);
 	return 1;
 }
 
-int send_message_path(const char *path, const char *msg, char **reply, int signalpid)
+/* Called by an app to ask the consumer daemon to connect to it. */
+
+int ustcomm_request_consumer(pid_t pid, const char *channel)
 {
-	int fd;
+	char path[UNIX_PATH_MAX];
 	int result;
-	struct sockaddr_un addr;
-
-	result = fd = socket(PF_UNIX, SOCK_STREAM, 0);
-	if(result == -1) {
-		PERROR("socket");
-		return -1;
+	char *msg=NULL;
+	int retval = 0;
+	struct ustcomm_connection conn;
+	char *explicit_daemon_socket_path;
+
+	explicit_daemon_socket_path = getenv("UST_DAEMON_SOCKET");
+	if(explicit_daemon_socket_path) {
+		/* user specified explicitly a socket path */
+		result = snprintf(path, UNIX_PATH_MAX, "%s", explicit_daemon_socket_path);
+	}
+	else {
+		/* just use the default path */
+		result = snprintf(path, UNIX_PATH_MAX, "%s/ustd", SOCK_DIR);
 	}
 
-	addr.sun_family = AF_UNIX;
-
-	result = snprintf(addr.sun_path, UNIX_PATH_MAX, "%s", path);
 	if(result >= UNIX_PATH_MAX) {
 		ERR("string overflow allocating socket name");
 		return -1;
 	}
 
-	if(signalpid >= 0)
-		signal_process(signalpid);
+	asprintf(&msg, "collect %d %s", pid, channel); 
 
-	result = connect(fd, (struct sockaddr *)&addr, sizeof(addr));
+	/* don't signal it because it's the daemon */
+	result = ustcomm_connect_path(path, &conn, -1);
 	if(result == -1) {
-		PERROR("connect");
-		return -1;
+		WARN("ustcomm_connect_path failed");
+		retval = -1;
+		goto del_string;
 	}
 
-	return send_message_fd(fd, msg, reply);
-}
-
-/* pid: the pid of the trace process that must receive the msg
-   msg: pointer to a null-terminated message to send
-   reply: location where to put the null-terminated string of the reply;
-	  it must be free'd after usage
- */
-
-int send_message(pid_t pid, const char *msg, char **reply)
-{
-	int result;
-	char path[UNIX_PATH_MAX];
-
-	result = snprintf(path, UNIX_PATH_MAX, "%s/%d", SOCK_DIR, pid);
-	if(result >= UNIX_PATH_MAX) {
-		fprintf(stderr, "string overflow allocating socket name");
-		return -1;
+	result = ustcomm_send_request(&conn, msg, NULL);
+	if(result == -1) {
+		WARN("ustcomm_send_request failed");
+		retval = -1;
+		goto disconnect;
 	}
 
-	send_message_path(path, msg, reply, pid);
+	disconnect:
+	ustcomm_disconnect(&conn);
+	del_string:
+	free(msg);
 
-	return 0;
+	return retval;
 }
 
-/* Called by an app to ask the consumer daemon to connect to it. */
+/* returns 1 to indicate a message was received
+ * returns 0 to indicate no message was received (end of stream)
+ * returns -1 to indicate an error
+ */
 
-int ustcomm_request_consumer(pid_t pid, const char *channel)
+#define RECV_INCREMENT 1000
+#define RECV_INITIAL_BUF_SIZE 10
+
+static int recv_message_fd(int fd, char **recv_buf, int *recv_buf_size, int *recv_buf_alloc, char **msg)
 {
-	char path[UNIX_PATH_MAX];
 	int result;
-	char *msg;
 
-	result = snprintf(path, UNIX_PATH_MAX, "%s/ustd", SOCK_DIR);
-	if(result >= UNIX_PATH_MAX) {
-		fprintf(stderr, "string overflow allocating socket name");
-		return -1;
-	}
+	/* 1. Check if there is a message in the buf */
+	/* 2. If not, do:
+           2.1 receive chunk and put it in buffer
+	   2.2 process full message if there is one
+	   -- while no message arrived
+	*/
 
-	asprintf(&msg, "collect %d %s", pid, channel); 
+	for(;;) {
+		int i;
+		int nulfound = 0;
+
+		/* Search for full message in buffer */
+		for(i=0; i<*recv_buf_size; i++) {
+			if((*recv_buf)[i] == '\0') {
+				nulfound = 1;
+				break;
+			}
+		}
 
-	send_message_path(path, msg, NULL, -1);
-	free(msg);
+		/* Process found message */
+		if(nulfound == 1) {
+			char *newbuf;
 
-	return 0;
-}
+			if(i == 0) {
+				/* problem */
+				WARN("received empty message");
+			}
+			*msg = strndup(*recv_buf, i);
 
-/* returns 1 to indicate a message was received
- * returns 0 to indicate no message was received (cannot happen)
- * returns -1 to indicate an error
- */
+			/* Remove processed message from buffer */
+			newbuf = (char *) malloc(*recv_buf_size - (i+1));
+			memcpy(newbuf, *recv_buf + (i+1), *recv_buf_size - (i+1));
+			free(*recv_buf);
+			*recv_buf = newbuf;
+			*recv_buf_size -= (i+1);
+			*recv_buf_alloc -= (i+1);
 
-static int recv_message_fd(int fd, char **msg, struct ustcomm_source *src)
-{
-	int result;
+			return 1;
+		}
 
-	*msg = (char *) malloc(MSG_MAX+1);
+		/* Receive a chunk from the fd */
+		if(*recv_buf_alloc - *recv_buf_size < RECV_INCREMENT) {
+			*recv_buf_alloc += RECV_INCREMENT - (*recv_buf_alloc - *recv_buf_size);
+			*recv_buf = (char *) realloc(*recv_buf, *recv_buf_alloc);
+		}
 
-	result = recv(fd, *msg, MSG_MAX, 0);
-	if(result == -1) {
-		PERROR("recv");
-		return -1;
-	}
+		result = recv(fd, *recv_buf+*recv_buf_size, RECV_INCREMENT, 0);
+		if(result == -1) {
+			if(errno == ECONNRESET) {
+				*recv_buf_size = 0;
+				return 0;
+			}
+			else if(errno == EINTR) {
+				return -1;
+			}
+			else {
+				PERROR("recv");
+				return -1;
+			}
+		}
+		if(result == 0) {
+			return 0;
+		}
+		*recv_buf_size += result;
 
-	(*msg)[result] = '\0';
-	
-	DBG("ustcomm_app_recv_message: result is %d, message is %s", result, (*msg));
+		/* Go back to the beginning to check if there is a full message in the buffer */
+	}
 
-	if(src)
-		src->fd = fd;
+	DBG("received message \"%s\"", *recv_buf);
 
 	return 1;
+
+}
+
+static int recv_message_conn(struct ustcomm_connection *conn, char **msg)
+{
+	return recv_message_fd(conn->fd, &conn->recv_buf, &conn->recv_buf_size, &conn->recv_buf_alloc, msg);
 }
 
 int ustcomm_send_reply(struct ustcomm_server *server, char *msg, struct ustcomm_source *src)
 {
 	int result;
 
-	result = send_message_fd(src->fd, msg, NULL);
-	if(result) {
+	result = send_message_fd(src->fd, msg);
+	if(result < 0) {
 		ERR("error in send_message_fd");
 		return -1;
 	}
@@ -209,6 +292,23 @@ int ustcomm_send_reply(struct ustcomm_server *server, char *msg, struct ustcomm_
 	return 0;
 } 
 
+/* Called after a fork. */
+
+int ustcomm_close_all_connections(struct ustcomm_server *server)
+{
+	struct ustcomm_connection *conn;
+	struct ustcomm_connection *deletable_conn = NULL;
+
+	list_for_each_entry(conn, &server->connections, list) {
+		free(deletable_conn);
+		deletable_conn = conn;
+		ustcomm_close_app(conn);
+		list_del(&conn->list);
+	}
+
+	return 0;
+}
+
 /* @timeout: max blocking time in milliseconds, -1 means infinity
  *
  * returns 1 to indicate a message was received
@@ -219,6 +319,7 @@ int ustcomm_send_reply(struct ustcomm_server *server, char *msg, struct ustcomm_
 int ustcomm_recv_message(struct ustcomm_server *server, char **msg, struct ustcomm_source *src, int timeout)
 {
 	struct pollfd *fds;
+	struct ustcomm_connection **conn_table;
 	struct ustcomm_connection *conn;
 	int result;
 	int retval;
@@ -231,12 +332,19 @@ int ustcomm_recv_message(struct ustcomm_server *server, char **msg, struct ustco
 			n_fds++;
 		}
 
-		fds = (struct pollfd *) malloc(n_fds * sizeof(struct pollfd));
+		fds = (struct pollfd *) zmalloc(n_fds * sizeof(struct pollfd));
 		if(fds == NULL) {
-			ERR("malloc returned NULL");
+			ERR("zmalloc returned NULL");
 			return -1;
 		}
 
+		conn_table = (struct ustcomm_connection **) zmalloc(n_fds * sizeof(struct ustcomm_connection *));
+		if(conn_table == NULL) {
+			ERR("zmalloc returned NULL");
+			retval = -1;
+			goto free_fds_return;
+		}
+
 		/* special idx 0 is for listening socket */
 		fds[idx].fd = server->listen_fd;
 		fds[idx].events = POLLIN;
@@ -245,17 +353,25 @@ int ustcomm_recv_message(struct ustcomm_server *server, char **msg, struct ustco
 		list_for_each_entry(conn, &server->connections, list) {
 			fds[idx].fd = conn->fd;
 			fds[idx].events = POLLIN;
+			conn_table[idx] = conn;
 			idx++;
 		}
 
 		result = poll(fds, n_fds, timeout);
-		if(result == -1) {
+		if(result == -1 && errno == EINTR) {
+			/* That's ok. ustd receives signals to notify it must shutdown. */
+			retval = -1;
+			goto free_conn_table_return;
+		}
+		else if(result == -1) {
 			PERROR("poll");
-			return -1;
+			retval = -1;
+			goto free_conn_table_return;
+		}
+		else if(result == 0) {
+			retval = 0;
+			goto free_conn_table_return;
 		}
-
-		if(result == 0)
-			return 0;
 
 		if(fds[0].revents) {
 			struct ustcomm_connection *newconn;
@@ -264,15 +380,17 @@ int ustcomm_recv_message(struct ustcomm_server *server, char **msg, struct ustco
 			result = newfd = accept(server->listen_fd, NULL, NULL);
 			if(result == -1) {
 				PERROR("accept");
-				return -1;
+				retval = -1;
+				goto free_conn_table_return;
 			}
 
-			newconn = (struct ustcomm_connection *) malloc(sizeof(struct ustcomm_connection));
+			newconn = (struct ustcomm_connection *) zmalloc(sizeof(struct ustcomm_connection));
 			if(newconn == NULL) {
-				ERR("malloc returned NULL");
+				ERR("zmalloc returned NULL");
 				return -1;
 			}
 
+			ustcomm_init_connection(newconn);
 			newconn->fd = newfd;
 
 			list_add(&newconn->list, &server->connections);
@@ -280,27 +398,33 @@ int ustcomm_recv_message(struct ustcomm_server *server, char **msg, struct ustco
 
 		for(idx=1; idx<n_fds; idx++) {
 			if(fds[idx].revents) {
-				retval = recv_message_fd(fds[idx].fd, msg, src);
-				if(**msg == 0) {
-					/* connection finished */
-					close(fds[idx].fd);
+				retval = recv_message_conn(conn_table[idx], msg);
+				if(src)
+					src->fd = fds[idx].fd;
 
+				if(retval == 0) {
+					/* connection finished */
 					list_for_each_entry(conn, &server->connections, list) {
 						if(conn->fd == fds[idx].fd) {
+							ustcomm_close_app(conn);
 							list_del(&conn->list);
+							free(conn);
 							break;
 						}
 					}
 				}
 				else {
-					goto free_fds_return;
+					goto free_conn_table_return;
 				}
 			}
 		}
 
 		free(fds);
+		free(conn_table);
 	}
 
+free_conn_table_return:
+	free(conn_table);
 free_fds_return:
 	free(fds);
 	return retval;
@@ -316,7 +440,27 @@ int ustcomm_app_recv_message(struct ustcomm_app *app, char **msg, struct ustcomm
 	return ustcomm_recv_message(&app->server, msg, src, timeout);
 }
 
-static int init_named_socket(char *name, char **path_out)
+/* This removes src from the list of active connections of app.
+ */
+
+int ustcomm_app_detach_client(struct ustcomm_app *app, struct ustcomm_source *src)
+{
+	struct ustcomm_server *server = (struct ustcomm_server *)app;
+	struct ustcomm_connection *conn;
+
+	list_for_each_entry(conn, &server->connections, list) {
+		if(conn->fd == src->fd) {
+			list_del(&conn->list);
+			goto found;
+		}
+	}
+
+	return -1;
+found:
+	return src->fd;
+}
+
+static int init_named_socket(const char *name, char **path_out)
 {
 	int result;
 	int fd;
@@ -342,7 +486,7 @@ static int init_named_socket(char *name, char **path_out)
 			PERROR("unlink of socket file");
 			goto close_sock;
 		}
-		WARN("socket already exists; overwriting");
+		DBG("socket already exists; overwriting");
 	}
 
 	result = bind(fd, (struct sockaddr *)&addr, sizeof(addr));
@@ -358,8 +502,7 @@ static int init_named_socket(char *name, char **path_out)
 	}
 
 	if(path_out) {
-		*path_out = "";
-		*path_out = strdupa(addr.sun_path);
+		*path_out = strdup(addr.sun_path);
 	}
 
 	return fd;
@@ -370,6 +513,156 @@ static int init_named_socket(char *name, char **path_out)
 	return -1;
 }
 
+/*
+ * Return value:
+ *   0: Success, but no reply because recv() returned 0
+ *   1: Success
+ *   -1: Error
+ *
+ * On error, the error message is printed, except on
+ * ECONNRESET, which is normal when the application dies.
+ */
+
+int ustcomm_send_request(struct ustcomm_connection *conn, const char *req, char **reply)
+{
+	int result;
+
+	/* Send including the final \0 */
+	result = send_message_fd(conn->fd, req);
+	if(result != 1)
+		return result;
+
+	if(!reply)
+		return 1;
+
+	result = recv_message_conn(conn, reply);
+	if(result == -1) {
+		return -1;
+	}
+	else if(result == 0) {
+		return 0;
+	}
+	
+	return 1;
+}
+
+/* Return value:
+ *  0: success
+ * -1: error
+ */
+
+int ustcomm_connect_path(const char *path, struct ustcomm_connection *conn, pid_t signalpid)
+{
+	int fd;
+	int result;
+	struct sockaddr_un addr;
+
+	ustcomm_init_connection(conn);
+
+	result = fd = socket(PF_UNIX, SOCK_STREAM, 0);
+	if(result == -1) {
+		PERROR("socket");
+		return -1;
+	}
+
+	addr.sun_family = AF_UNIX;
+
+	result = snprintf(addr.sun_path, UNIX_PATH_MAX, "%s", path);
+	if(result >= UNIX_PATH_MAX) {
+		ERR("string overflow allocating socket name");
+		return -1;
+	}
+
+	if(signalpid >= 0) {
+		result = signal_process(signalpid);
+		if(result == -1) {
+			ERR("could not signal process");
+			return -1;
+		}
+	}
+
+	result = connect(fd, (struct sockaddr *)&addr, sizeof(addr));
+	if(result == -1) {
+		PERROR("connect (path=%s)", path);
+		return -1;
+	}
+
+	conn->fd = fd;
+
+	return 0;
+}
+
+int ustcomm_disconnect(struct ustcomm_connection *conn)
+{
+	return close(conn->fd);
+}
+
+/* Open a connection to a traceable app.
+ *
+ * Return value:
+ *  0: success
+ * -1: error
+ */
+
+int ustcomm_connect_app(pid_t pid, struct ustcomm_connection *conn)
+{
+	int result;
+	char path[UNIX_PATH_MAX];
+
+
+	result = snprintf(path, UNIX_PATH_MAX, "%s/%d", SOCK_DIR, pid);
+	if(result >= UNIX_PATH_MAX) {
+		ERR("string overflow allocating socket name");
+		return -1;
+	}
+
+	return ustcomm_connect_path(path, conn, pid);
+}
+
+/* Close a connection to a traceable app. It frees the
+ * resources. It however does not free the
+ * ustcomm_connection itself.
+ */
+
+int ustcomm_close_app(struct ustcomm_connection *conn)
+{
+	close(conn->fd);
+	free(conn->recv_buf);
+
+	return 0;
+}
+
+static int ensure_dir_exists(const char *dir)
+{
+	struct stat st;
+	int result;
+
+	if(!strcmp(dir, ""))
+		return -1;
+
+	result = stat(dir, &st);
+	if(result == -1 && errno != ENOENT) {
+		return -1;
+	}
+	else if(result == -1) {
+		/* ENOENT */
+		int result;
+
+		/* mkdir mode to 0777 */
+		result = mkdir_p(dir, S_IRWXU | S_IRWXG | S_IRWXO);
+		if(result != 0) {
+			ERR("executing in recursive creation of directory %s", dir);
+			return -1;
+		}
+	}
+
+	return 0;
+}
+
+/* Called by an application to initialize its server so daemons can
+ * connect to it.
+ */
+
 int ustcomm_init_app(pid_t pid, struct ustcomm_app *handle)
 {
 	int result;
@@ -381,9 +674,15 @@ int ustcomm_init_app(pid_t pid, struct ustcomm_app *handle)
 		return -1;
 	}
 
+	result = ensure_dir_exists(SOCK_DIR);
+	if(result == -1) {
+		ERR("Unable to create socket directory %s", SOCK_DIR);
+		return -1;
+	}
+
 	handle->server.listen_fd = init_named_socket(name, &(handle->server.socketpath));
 	if(handle->server.listen_fd < 0) {
-		ERR("error initializing named socket");
+		ERR("Error initializing named socket (%s). Check that directory exists and that it is writable.", name);
 		goto free_name;
 	}
 	free(name);
@@ -397,34 +696,96 @@ free_name:
 	return -1;
 }
 
-int ustcomm_init_ustd(struct ustcomm_ustd *handle)
+/* Used by the daemon to initialize its server so applications
+ * can connect to it.
+ */
+
+int ustcomm_init_ustd(struct ustcomm_ustd *handle, const char *sock_path)
 {
-	int result;
 	char *name;
+	int retval = 0;
 
-	result = asprintf(&name, "%s/%s", SOCK_DIR, "ustd");
-	if(result >= UNIX_PATH_MAX) {
-		ERR("string overflow allocating socket name");
-		return -1;
+	if(sock_path) {
+		asprintf(&name, "%s", sock_path);
+	}
+	else {
+		int result;
+
+		/* Only check if socket dir exists if we are using the default directory */
+		result = ensure_dir_exists(SOCK_DIR);
+		if(result == -1) {
+			ERR("Unable to create socket directory %s", SOCK_DIR);
+			return -1;
+		}
+
+		asprintf(&name, "%s/%s", SOCK_DIR, "ustd");
 	}
 
 	handle->server.listen_fd = init_named_socket(name, &handle->server.socketpath);
 	if(handle->server.listen_fd < 0) {
-		ERR("error initializing named socket");
+		ERR("error initializing named socket at %s", name);
+		retval = -1;
 		goto free_name;
 	}
-	free(name);
 
 	INIT_LIST_HEAD(&handle->server.connections);
 
-	return 0;
-
 free_name:
 	free(name);
-	return -1;
+
+	return retval;
 }
 
-static char *find_tok(char *str)
+static void ustcomm_fini_server(struct ustcomm_server *server, int keep_socket_file)
+{
+	int result;
+	struct stat st;
+
+	if(!keep_socket_file) {
+		/* Destroy socket */
+		result = stat(server->socketpath, &st);
+		if(result == -1) {
+			PERROR("stat (%s)", server->socketpath);
+			return;
+		}
+
+		/* Paranoid check before deleting. */
+		result = S_ISSOCK(st.st_mode);
+		if(!result) {
+			ERR("The socket we are about to delete is not a socket.");
+			return;
+		}
+
+		result = unlink(server->socketpath);
+		if(result == -1) {
+			PERROR("unlink");
+		}
+	}
+
+	free(server->socketpath);
+
+	result = close(server->listen_fd);
+	if(result == -1) {
+		PERROR("close");
+		return;
+	}
+}
+
+/* Free a traceable application server */
+
+void ustcomm_fini_app(struct ustcomm_app *handle, int keep_socket_file)
+{
+	ustcomm_fini_server(&handle->server, keep_socket_file);
+}
+
+/* Free a ustd server */
+
+void ustcomm_fini_ustd(struct ustcomm_ustd *handle)
+{
+	ustcomm_fini_server(&handle->server, 0);
+}
+
+static const char *find_tok(const char *str)
 {
 	while(*str == ' ') {
 		str++;
@@ -436,7 +797,7 @@ static char *find_tok(char *str)
 	return str;
 }
 
-static char *find_sep(char *str)
+static const char *find_sep(const char *str)
 {
 	while(*str != ' ') {
 		str++;
@@ -448,11 +809,11 @@ static char *find_sep(char *str)
 	return str;
 }
 
-int nth_token_is(char *str, char *token, int tok_no)
+int nth_token_is(const char *str, const char *token, int tok_no)
 {
 	int i;
-	char *start;
-	char *end;
+	const char *start;
+	const char *end;
 
 	for(i=0; i<=tok_no; i++) {
 		str = find_tok(str);
@@ -477,12 +838,12 @@ int nth_token_is(char *str, char *token, int tok_no)
 	return 1;
 }
 
-char *nth_token(char *str, int tok_no)
+char *nth_token(const char *str, int tok_no)
 {
 	static char *retval = NULL;
 	int i;
-	char *start;
-	char *end;
+	const char *start;
+	const char *end;
 
 	for(i=0; i<=tok_no; i++) {
 		str = find_tok(str);
@@ -508,3 +869,88 @@ char *nth_token(char *str, int tok_no)
 	return retval;
 }
 
+/* Callback from multipoll.
+ * Receive a new connection on the listening socket.
+ */
+
+static int process_mp_incoming_conn(void *priv, int fd, short events)
+{
+	struct ustcomm_connection *newconn;
+	struct ustcomm_server *server = (struct ustcomm_server *) priv;
+	int newfd;
+	int result;
+
+	result = newfd = accept(server->listen_fd, NULL, NULL);
+	if(result == -1) {
+		PERROR("accept");
+		return -1;
+	}
+
+	newconn = (struct ustcomm_connection *) zmalloc(sizeof(struct ustcomm_connection));
+	if(newconn == NULL) {
+		ERR("zmalloc returned NULL");
+		return -1;
+	}
+
+	ustcomm_init_connection(newconn);
+	newconn->fd = newfd;
+
+	list_add(&newconn->list, &server->connections);
+
+	return 0;
+}
+
+/* Callback from multipoll.
+ * Receive a message on an existing connection.
+ */
+
+static int process_mp_conn_msg(void *priv, int fd, short revents)
+{
+	struct ustcomm_multipoll_conn_info *mpinfo = (struct ustcomm_multipoll_conn_info *) priv;
+	int result;
+	char *msg;
+	struct ustcomm_source src;
+
+	if(revents) {
+		src.fd = fd;
+
+		result = recv_message_conn(mpinfo->conn, &msg);
+		if(result == -1) {
+			ERR("error in recv_message_conn");
+		}
+
+		else if(result == 0) {
+			/* connection finished */
+			ustcomm_close_app(mpinfo->conn);
+			list_del(&mpinfo->conn->list);
+			free(mpinfo->conn);
+		}
+		else {
+			mpinfo->cb(msg, &src);
+			free(msg);
+		}
+	}
+
+	return 0;
+}
+
+int free_ustcomm_client_poll(void *data)
+{
+	free(data);
+	return 0;
+}
+
+void ustcomm_mp_add_app_clients(struct mpentries *ent, struct ustcomm_app *app, int (*cb)(char *recvbuf, struct ustcomm_source *src))
+{
+	struct ustcomm_connection *conn;
+
+	/* add listener socket */
+	multipoll_add(ent, app->server.listen_fd, POLLIN, process_mp_incoming_conn, &app->server, NULL);
+
+	list_for_each_entry(conn, &app->server.connections, list) {
+		struct ustcomm_multipoll_conn_info *mpinfo = (struct ustcomm_multipoll_conn_info *) zmalloc(sizeof(struct ustcomm_multipoll_conn_info));
+		mpinfo->conn = conn;
+		mpinfo->cb = cb;
+		multipoll_add(ent, conn->fd, POLLIN, process_mp_conn_msg, mpinfo, free_ustcomm_client_poll);
+	}
+}