Tested TLS on MacOS and fixed a couple of issues with unix sockets

src/server.c

@@ -220,7 +220,14 @@ int dqlite_node_set_bind_address(dqlite_node *t, const char *address)
  /* Auto bind */
  len = 0;
  } else {
- strcpy(addr_un.sun_path + 1, address + 1);
+#if defined(__linux__)
+ // Linux abstract socket requires \0 in sun_path[0]
+ strncat(addr_un.sun_path + 1, address + 1, sizeof(addr_un.sun_path) - 1);
+#else
+ // MacOS do not support abstract sockets
+ strncat(addr_un.sun_path, address + 1, sizeof(addr_un.sun_path));
+ (void)unlink(addr_un.sun_path);
+#endif
  }
  len += sizeof(sa_family_t);
  addr = (struct sockaddr *)&addr_un;
@@ -458,26 +465,30 @@ static void listenCb(uv_stream_t *listener, int status)
  /* We accept unix socket connections only from the same process. */
  if (listener->type == UV_NAMED_PIPE) {
  int fd = stream->io_watcher.fd;
-#if defined(__APPLE__) || defined(__FreeBSD__)
- pid_t pid = -1;
- socklen_t len = sizeof(pid);
- rv = getsockopt(fd, SOL_SOCKET, LOCAL_PEERPID, &pid, &len);
+#if defined(SO_PEERCRED) // Linux
+ struct ucred cred;
+ socklen_t len = sizeof(cred);
+ rv = getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &cred, &len);
  if (rv != 0) {
  goto err;
  }
- if (pid != getpid()) {
+ if (cred.pid != getpid()) {
  goto err;
  }
-#else
- struct ucred cred;
- socklen_t len = sizeof(cred);
- rv = getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &cred, &len);
+#elif defined(LOCAL_PEERPID) // BSD
+ pid_t pid = -1;
+ socklen_t len = sizeof(pid);
+ rv = getsockopt(fd, SOL_LOCAL, LOCAL_PEERPID, &pid, &len);
  if (rv != 0) {
  goto err;
  }
- if (cred.pid != getpid()) {
+ if (pid != getpid()) {
  goto err;
  }
+#else
+ // The unix socket connection can't be verified and from
+ // security perspective it's better to block it entirely
+ goto err;
 #endif
  }