/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ /*** This file is part of systemd. Copyright 2010 Lennart Poettering systemd 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. systemd 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 systemd; If not, see <http://www.gnu.org/licenses/>. ***/ #include <sys/socket.h> #include <net/if.h> #include <asm/types.h> #include <netinet/in.h> #include <string.h> #include <stdlib.h> #include <unistd.h> #include "util.h" #include "macro.h" #include "loopback-setup.h" #include "socket-util.h" #include "sd-rtnl.h" #include "rtnl-util.h" /* this is hardcoded in the kernel, so don't look it up */ #define LOOPBACK_IFINDEX 1 static int start_loopback(sd_rtnl *rtnl) { _cleanup_rtnl_message_unref_ sd_rtnl_message *req = NULL; int r; r = sd_rtnl_message_new_link(rtnl, &req, RTM_SETLINK, LOOPBACK_IFINDEX); if (r < 0) return r; r = sd_rtnl_message_link_set_flags(req, IFF_UP, IFF_UP); if (r < 0) return r; r = sd_rtnl_call(rtnl, req, 0, NULL); if (r < 0) return r; return 0; } static int check_loopback(void) { int r; _cleanup_close_ int fd = -1; union { struct sockaddr sa; struct sockaddr_in in; } sa = { .in.sin_family = AF_INET, .in.sin_addr.s_addr = INADDR_LOOPBACK, }; /* If we failed to set up the loop back device, check whether * it might already be set up */ fd = socket(AF_INET, SOCK_DGRAM|SOCK_NONBLOCK|SOCK_CLOEXEC, 0); if (fd < 0) return -errno; if (bind(fd, &sa.sa, sizeof(sa.in)) >= 0) r = 1; else r = errno == EADDRNOTAVAIL ? 0 : -errno; return r; } int loopback_setup(void) { _cleanup_rtnl_unref_ sd_rtnl *rtnl = NULL; int r; r = sd_rtnl_open(&rtnl, 0); if (r < 0) return r; r = start_loopback(rtnl); if (r == -EPERM) { if (check_loopback() < 0) { log_warning("Failed to configure loopback device: %s", strerror(EPERM)); return -EPERM; } } else if (r < 0) { log_warning("Failed to configure loopback device: %s", strerror(-r)); return r; } return 0; }