tree-wide: introduce new SOCKADDR_UN_LEN() macro, and use it everywhere

The macro determines the right length of a AF_UNIX "struct sockaddr_un" to pass to
connect() or bind(). It automatically figures out if the socket refers to an
abstract namespace socket, or a socket in the file system, and properly handles
the full length of the path field.

This macro is not only safer, but also simpler to use, than the usual
offsetof() + strlen() logic.

5 files changed, 30 insertions, 31 deletions

diff --git a/src/journal/journal-send.c b/src/journal/journal-send.c
index f0959b6237..5e8a3e3200 100644
--- a/src/journal/journal-send.c
+++ b/src/journal/journal-send.c
@@ -208,13 +208,13 @@ _public_ int sd_journal_sendv(const struct iovec *iov, int n) {
         struct iovec *w;
         uint64_t *l;
         int i, j = 0;
-        struct sockaddr_un sa = {
-                .sun_family = AF_UNIX,
-                .sun_path = "/run/systemd/journal/socket",
+        static const union sockaddr_union sa = {
+                .un.sun_family = AF_UNIX,
+                .un.sun_path = "/run/systemd/journal/socket",
         };
         struct msghdr mh = {
-                .msg_name = &sa,
-                .msg_namelen = offsetof(struct sockaddr_un, sun_path) + strlen(sa.sun_path),
+                .msg_name = (struct sockaddr*) &sa.sa,
+                .msg_namelen = SOCKADDR_UN_LEN(sa.un),
         };
         ssize_t k;
         bool have_syslog_identifier = false;
@@ -392,7 +392,7 @@ _public_ int sd_journal_perror(const char *message) {
 }
 
 _public_ int sd_journal_stream_fd(const char *identifier, int priority, int level_prefix) {
-        union sockaddr_union sa = {
+        static const union sockaddr_union sa = {
                 .un.sun_family = AF_UNIX,
                 .un.sun_path = "/run/systemd/journal/stdout",
         };
@@ -408,7 +408,7 @@ _public_ int sd_journal_stream_fd(const char *identifier, int priority, int leve
         if (fd < 0)
                 return -errno;
 
-        r = connect(fd, &sa.sa, offsetof(union sockaddr_union, un.sun_path) + strlen(sa.un.sun_path));
+        r = connect(fd, &sa.sa, SOCKADDR_UN_LEN(sa.un));
         if (r < 0)
                 return -errno;
 
diff --git a/src/journal/journald-native.c b/src/journal/journald-native.c
index a445291a5e..0a1ce205c2 100644
--- a/src/journal/journald-native.c
+++ b/src/journal/journald-native.c
@@ -448,24 +448,24 @@ void server_process_native_file(
 }
 
 int server_open_native_socket(Server*s) {
+
+        static const union sockaddr_union sa = {
+                .un.sun_family = AF_UNIX,
+                .un.sun_path = "/run/systemd/journal/socket",
+        };
         static const int one = 1;
         int r;
 
         assert(s);
 
         if (s->native_fd < 0) {
-                union sockaddr_union sa = {
-                        .un.sun_family = AF_UNIX,
-                        .un.sun_path = "/run/systemd/journal/socket",
-                };
-
                 s->native_fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
                 if (s->native_fd < 0)
                         return log_error_errno(errno, "socket() failed: %m");
 
-                unlink(sa.un.sun_path);
+                (void) unlink(sa.un.sun_path);
 
-                r = bind(s->native_fd, &sa.sa, offsetof(union sockaddr_union, un.sun_path) + strlen(sa.un.sun_path));
+                r = bind(s->native_fd, &sa.sa, SOCKADDR_UN_LEN(sa.un));
                 if (r < 0)
                         return log_error_errno(errno, "bind(%s) failed: %m", sa.un.sun_path);
 
diff --git a/src/journal/journald-server.c b/src/journal/journald-server.c
index e14d0ad980..8f82d2a838 100644
--- a/src/journal/journald-server.c
+++ b/src/journal/journald-server.c
@@ -1696,7 +1696,7 @@ static int server_connect_notify(Server *s) {
         if (sa.un.sun_path[0] == '@')
                 sa.un.sun_path[0] = 0;
 
-        r = connect(s->notify_fd, &sa.sa, offsetof(struct sockaddr_un, sun_path) + strlen(e));
+        r = connect(s->notify_fd, &sa.sa, SOCKADDR_UN_LEN(sa.un));
         if (r < 0)
                 return log_error_errno(errno, "Failed to connect to notify socket: %m");
 
diff --git a/src/journal/journald-stream.c b/src/journal/journald-stream.c
index 59352bcb3f..4ad16ee41c 100644
--- a/src/journal/journald-stream.c
+++ b/src/journal/journald-stream.c
@@ -700,23 +700,22 @@ fail:
 }
 
 int server_open_stdout_socket(Server *s) {
+        static const union sockaddr_union sa = {
+                .un.sun_family = AF_UNIX,
+                .un.sun_path = "/run/systemd/journal/stdout",
+        };
         int r;
 
         assert(s);
 
         if (s->stdout_fd < 0) {
-                union sockaddr_union sa = {
-                        .un.sun_family = AF_UNIX,
-                        .un.sun_path = "/run/systemd/journal/stdout",
-                };
-
                 s->stdout_fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
                 if (s->stdout_fd < 0)
                         return log_error_errno(errno, "socket() failed: %m");
 
-                unlink(sa.un.sun_path);
+                (void) unlink(sa.un.sun_path);
 
-                r = bind(s->stdout_fd, &sa.sa, offsetof(union sockaddr_union, un.sun_path) + strlen(sa.un.sun_path));
+                r = bind(s->stdout_fd, &sa.sa, SOCKADDR_UN_LEN(sa.un));
                 if (r < 0)
                         return log_error_errno(errno, "bind(%s) failed: %m", sa.un.sun_path);
 
diff --git a/src/journal/journald-syslog.c b/src/journal/journald-syslog.c
index 5153fd0cce..ead47887d8 100644
--- a/src/journal/journald-syslog.c
+++ b/src/journal/journald-syslog.c
@@ -52,8 +52,7 @@ static void forward_syslog_iovec(Server *s, const struct iovec *iovec, unsigned
                 .msg_iov = (struct iovec *) iovec,
                 .msg_iovlen = n_iovec,
                 .msg_name = (struct sockaddr*) &sa.sa,
-                .msg_namelen = offsetof(union sockaddr_union, un.sun_path)
-                               + strlen("/run/systemd/journal/syslog"),
+                .msg_namelen = SOCKADDR_UN_LEN(sa.un),
         };
         struct cmsghdr *cmsg;
         union {
@@ -383,24 +382,24 @@ void server_process_syslog_message(
 }
 
 int server_open_syslog_socket(Server *s) {
+
+        static const union sockaddr_union sa = {
+                .un.sun_family = AF_UNIX,
+                .un.sun_path = "/run/systemd/journal/dev-log",
+        };
         static const int one = 1;
         int r;
 
         assert(s);
 
         if (s->syslog_fd < 0) {
-                static const union sockaddr_union sa = {
-                        .un.sun_family = AF_UNIX,
-                        .un.sun_path = "/run/systemd/journal/dev-log",
-                };
-
                 s->syslog_fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
                 if (s->syslog_fd < 0)
                         return log_error_errno(errno, "socket() failed: %m");
 
-                unlink(sa.un.sun_path);
+                (void) unlink(sa.un.sun_path);
 
-                r = bind(s->syslog_fd, &sa.sa, offsetof(union sockaddr_union, un.sun_path) + strlen(sa.un.sun_path));
+                r = bind(s->syslog_fd, &sa.sa, SOCKADDR_UN_LEN(sa.un));
                 if (r < 0)
                         return log_error_errno(errno, "bind(%s) failed: %m", sa.un.sun_path);
 
@@ -437,6 +436,7 @@ int server_open_syslog_socket(Server *s) {
 
 void server_maybe_warn_forward_syslog_missed(Server *s) {
         usec_t n;
+
         assert(s);
 
         if (s->n_forward_syslog_missed <= 0)