Remove compatibility code for abstract unix domain sockets.

Abstract sockets were introduced in paraslash-0.5.5 (2015-09-20). For
backwards compatibility, create_local_socket() was modified to create
an abtract socket *and* an ordinary pathname socket so that old audiod
clients (which connect to the pathname socket) would still work.

This patch breaks compatibility by going back to a single socket,
either abstract (Linux) or pathname (all other systems), as determined
in the first call to create_local_socket(). This allows to drop the
"abstract" argument of init_unix_addr() and the "mode" argument of
create_local_socket().

The code in net.c and the callers get quite a bit shorter since it
has to deal with only a single file descriptor and one type of socket.

diff --git a/afs.c b/afs.c
index 0946b6df3b0766f82f95f0cd100f039753543350..7f27b7dd2653d79a0a7679da3e80d2d9c55e37ac 100644 (file)
--- a/afs.c
+++ b/afs.c
@@ -649,15 +649,10 @@ static int setup_command_socket_or_die(void)
        char *socket_name = conf.afs_socket_arg;
 
        unlink(socket_name);
-       ret = create_local_socket(socket_name, 0);
+       ret = create_local_socket(socket_name);
        if (ret < 0) {
-               ret = create_local_socket(socket_name,
-                       S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IROTH);
-               if (ret < 0) {
-                       PARA_EMERG_LOG("%s: %s\n", para_strerror(-ret),
-                               socket_name);
-                       exit(EXIT_FAILURE);
-               }
+               PARA_EMERG_LOG("%s: %s\n", para_strerror(-ret), socket_name);
+               exit(EXIT_FAILURE);
        }
        socket_fd = ret;
        PARA_INFO_LOG("listening on socket %s (fd %d)\n", socket_name,

diff --git a/audiod.c b/audiod.c
index db69cf141a3833a5227c12ccba3f81a9e357e3b3..254bcb8d8c4bac2947e52c3310fb7051fe5f1153 100644 (file)
--- a/audiod.c
+++ b/audiod.c
@@ -183,22 +183,9 @@ static uid_t *uid_whitelist;
  */
 static struct status_task *stat_task = &status_task_struct;
 
-/*
- * The task for handling audiod commands.
- *
- * We need two listening sockets for backward compability: on Linux systems
- * fd[0] is an abstract socket (more precisely, a socket bound to an address in
- * the abstract namespace), and fd[1] is the usual pathname socket. On other
- * systems, fd[0] is negative, and only the pathname socket is used.
- *
- * For 0.5.x we accept connections on both sockets to make sure that old
- * para_audioc versions can still connect. New versions use only the abstract
- * socket. Hence after v0.6.0 we can go back to a single socket, either an
- * abstract one (Linux) or a pathname socket (all other systems).
- */
 struct command_task {
-       /** The local listening sockets. */
-       int fd[2];
+       /** The local listening socket. */
+       int fd;
        /** the associated task structure */
        struct task *task;
 };
@@ -1059,7 +1046,7 @@ static int parse_stream_args(void)
 }
 
 /* does not unlink socket on errors */
-static void init_local_sockets(struct command_task *ct)
+static void init_local_socket(struct command_task *ct)
 {
        if (conf.socket_given)
                socket_name = para_strdup(conf.socket_arg);
@@ -1072,12 +1059,10 @@ static void init_local_sockets(struct command_task *ct)
        PARA_NOTICE_LOG("local socket: %s\n", socket_name);
        if (conf.force_given)
                unlink(socket_name);
-       ct->fd[0] = create_local_socket(socket_name, 0);
-       ct->fd[1] = create_local_socket(socket_name,
-               S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH);
-       if (ct->fd[0] >= 0 || ct->fd[1] >= 0)
+       ct->fd = create_local_socket(socket_name);
+       if (ct->fd >= 0)
                return;
-       PARA_EMERG_LOG("%s\n", para_strerror(-ct->fd[1]));
+       PARA_EMERG_LOG("%s\n", para_strerror(-ct->fd));
        exit(EXIT_FAILURE);
 }
 
@@ -1104,16 +1089,12 @@ static int signal_post_select(struct sched *s, void *context)
 static void command_pre_select(struct sched *s, void *context)
 {
        struct command_task *ct = context;
-       int i;
-
-       for (i = 0; i < 2; i++)
-               if (ct->fd[i] >= 0)
-                       para_fd_set(ct->fd[i], &s->rfds, &s->max_fileno);
+       para_fd_set(ct->fd, &s->rfds, &s->max_fileno);
 }
 
 static int command_post_select(struct sched *s, void *context)
 {
-       int ret, i;
+       int ret;
        struct command_task *ct = context;
        static struct timeval last_status_dump;
        struct timeval tmp, delay;
@@ -1122,19 +1103,15 @@ static int command_post_select(struct sched *s, void *context)
        ret = task_get_notification(ct->task);
        if (ret < 0)
                return ret;
-       for (i = 0; i < 2; i++) {
-               if (ct->fd[i] < 0)
-                       continue;
-               ret = handle_connect(ct->fd[i], &s->rfds);
-               if (ret < 0) {
-                       PARA_ERROR_LOG("%s\n", para_strerror(-ret));
-                       if (ret == -E_AUDIOD_TERM) {
-                               task_notify_all(s, -ret);
-                               return ret;
-                       }
-               } else if (ret > 0)
-                       force = true;
-       }
+       ret = handle_connect(ct->fd, &s->rfds);
+       if (ret < 0) {
+               PARA_ERROR_LOG("%s\n", para_strerror(-ret));
+               if (ret == -E_AUDIOD_TERM) {
+                       task_notify_all(s, -ret);
+                       return ret;
+               }
+       } else if (ret > 0)
+               force = true;
        if (force == true)
                goto dump;
 
@@ -1162,7 +1139,7 @@ dump:
 
 static void init_command_task(struct command_task *ct)
 {
-       init_local_sockets(ct); /* doesn't return on errors */
+       init_local_socket(ct); /* doesn't return on errors */
 
        ct->task = task_register(&(struct task_info) {
                .name = "command",

diff --git a/net.c b/net.c
index fa7cd4b80a7d96b26e35add01ad97d9a123f138d..023d78d08175f2f3810af6dd387f5eec14a06dcc 100644 (file)
--- a/net.c
+++ b/net.c
@@ -818,25 +818,37 @@ int dccp_available_ccids(uint8_t **ccid_array)
        return nccids;
 }
 
-/**
- * Prepare a structure for \p AF_UNIX socket addresses.
- *
- * \param u Pointer to the struct to be prepared.
- * \param name The socket pathname.
+/*
+ * Prepare a structure for AF_UNIX socket addresses.
  *
- * This just copies \a name to the sun_path component of \a u.
+ * This just copies name to the sun_path component of u, prepending a zero byte
+ * if abstract sockets are supported.
  *
- * \return Positive on success, \p -E_NAME_TOO_LONG if \a name is longer
- * than \p UNIX_PATH_MAX.
+ * The first call to this function tries to bind a socket to the abstract name
+ * space. The result of this test is stored in a static variable. Subsequent
+ * calls read this variable and create abstract sockets on systems that support
+ * them.
  */
-static int init_unix_addr(struct sockaddr_un *u, const char *name,
-               bool abstract)
+static int init_unix_addr(struct sockaddr_un *u, const char *name)
 {
-       if (strlen(name) + abstract >= UNIX_PATH_MAX)
+       static int use_abstract;
+
+       if (strlen(name) + 1 >= UNIX_PATH_MAX)
                return -E_NAME_TOO_LONG;
        memset(u->sun_path, 0, UNIX_PATH_MAX);
        u->sun_family = PF_UNIX;
-       strcpy(u->sun_path + abstract, name);
+       if (use_abstract == 0) { /* executed only once */
+               int fd = socket(PF_UNIX, SOCK_STREAM, 0);
+               memcpy(u->sun_path, "\0x\0", 3);
+               if (bind(fd, (struct sockaddr *)u, sizeof(*u)) == 0)
+                       use_abstract = 1; /* yes */
+               else
+                       use_abstract = -1; /* no */
+               close(fd);
+               PARA_NOTICE_LOG("%susing abstract socket namespace\n",
+                       use_abstract == 1? "" : "not ");
+       }
+       strcpy(u->sun_path + (use_abstract == 1? 1 : 0), name);
        return 1;
 }
 
@@ -844,28 +856,22 @@ static int init_unix_addr(struct sockaddr_un *u, const char *name,
  * Create a socket for local communication and listen on it.
  *
  * \param name The socket pathname.
- * \param mode The desired permissions of the socket.
  *
  * This function creates a passive local socket for sequenced, reliable,
  * two-way, connection-based byte streams. The socket file descriptor is set to
  * nonblocking mode and listen(2) is called to prepare the socket for
  * accepting incoming connection requests.
  *
- * If mode is zero, an abstract socket (a non-portable Linux extension) is
- * created. In this case the socket name has no connection with filesystem
- * pathnames.
- *
  * \return The file descriptor on success, negative error code on failure.
  *
  * \sa socket(2), \sa bind(2), \sa chmod(2), listen(2), unix(7).
  */
-int create_local_socket(const char *name, mode_t mode)
+int create_local_socket(const char *name)
 {
        struct sockaddr_un unix_addr;
        int fd, ret;
-       bool abstract = mode == 0;
 
-       ret = init_unix_addr(&unix_addr, name, abstract);
+       ret = init_unix_addr(&unix_addr, name);
        if (ret < 0)
                return ret;
        ret = socket(PF_UNIX, SOCK_STREAM, 0);
@@ -880,7 +886,9 @@ int create_local_socket(const char *name, mode_t mode)
                ret = -ERRNO_TO_PARA_ERROR(errno);
                goto err;
        }
-       if (!abstract) {
+       if (unix_addr.sun_path[0] != 0) { /* pathname socket */
+               mode_t mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP
+                       | S_IROTH | S_IWOTH;
                ret = -E_CHMOD;
                if (chmod(name, mode) < 0)
                        goto err;
@@ -917,14 +925,7 @@ int connect_local_socket(const char *name)
        fd = socket(PF_UNIX, SOCK_STREAM, 0);
        if (fd < 0)
                return -ERRNO_TO_PARA_ERROR(errno);
-       /* first try (linux-only) abstract socket */
-       ret = init_unix_addr(&unix_addr, name, true);
-       if (ret < 0)
-               goto err;
-       if (connect(fd, (struct sockaddr *)&unix_addr, sizeof(unix_addr)) != -1)
-               return fd;
-       /* next try pathname socket */
-       ret = init_unix_addr(&unix_addr, name, false);
+       ret = init_unix_addr(&unix_addr, name);
        if (ret < 0)
                goto err;
        if (connect(fd, (struct sockaddr *)&unix_addr, sizeof(unix_addr)) != -1)

diff --git a/net.h b/net.h
index b2bb47c9b40b43fe2eb7c8813e6ffa7364b0853e..a70954a95fa742f5fedf27320f7d500bf20a2fa0 100644 (file)
--- a/net.h
+++ b/net.h
@@ -147,7 +147,7 @@ int recv_bin_buffer(int fd, char *buf, size_t size);
 int recv_buffer(int fd, char *buf, size_t size);
 
 int para_accept(int fd, fd_set *rfds, void *addr, socklen_t size, int *new_fd);
-int create_local_socket(const char *name, mode_t mode);
+int create_local_socket(const char *name);
 int connect_local_socket(const char *name);
 int recv_cred_buffer(int, char *, size_t);
 ssize_t send_cred_buffer(int, char*);