diff options
Diffstat (limited to 'pimd/mtracebis_routeget.c')
| -rw-r--r-- | pimd/mtracebis_routeget.c | 102 |
1 files changed, 102 insertions, 0 deletions
diff --git a/pimd/mtracebis_routeget.c b/pimd/mtracebis_routeget.c new file mode 100644 index 0000000..8d97440 --- /dev/null +++ b/pimd/mtracebis_routeget.c @@ -0,0 +1,102 @@ +/* + * Multicast Traceroute for FRRouting + * Copyright (C) 2018 Mladen Sablic + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program 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 + * General Public License for more details. + * + * You should have received a copy of the GNU General Public License along + * with this program; see the file COPYING; if not, write to the Free Software + * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA + */ + +#ifdef HAVE_CONFIG_H +#include "config.h" +#endif + +#ifdef __linux__ + +#include <asm/types.h> +#include <linux/netlink.h> +#include <linux/rtnetlink.h> +#include <sys/types.h> +#include <stdio.h> +#include <arpa/inet.h> +#include <string.h> + +#include "mtracebis_netlink.h" +#include "mtracebis_routeget.h" + +static int find_dst(struct nlmsghdr *n, struct in_addr *src, struct in_addr *gw) +{ + struct rtmsg *r = NLMSG_DATA(n); + int len = n->nlmsg_len; + struct rtattr *tb[RTA_MAX + 1]; + + len -= NLMSG_LENGTH(sizeof(*r)); + if (len < 0) { + fprintf(stderr, "BUG: wrong nlmsg len %d\n", len); + return -1; + } + + parse_rtattr(tb, RTA_MAX, RTM_RTA(r), len); + if (tb[RTA_PREFSRC]) + src->s_addr = *(uint32_t *)RTA_DATA(tb[RTA_PREFSRC]); + if (tb[RTA_GATEWAY]) + gw->s_addr = *(uint32_t *)RTA_DATA(tb[RTA_GATEWAY]); + if (tb[RTA_OIF]) + return *(int *)RTA_DATA(tb[RTA_OIF]); + return 0; +} + +int routeget(struct in_addr dst, struct in_addr *src, struct in_addr *gw) +{ + struct { + struct nlmsghdr n; + struct rtmsg r; + char buf[1024]; + } req; + int ret; + struct rtnl_handle rth = {.fd = -1}; + + memset(&req, 0, sizeof(req)); + + req.n.nlmsg_len = NLMSG_LENGTH(sizeof(struct rtmsg)); + req.n.nlmsg_flags = NLM_F_REQUEST; + req.n.nlmsg_type = RTM_GETROUTE; + req.r.rtm_family = AF_INET; + req.r.rtm_table = 0; + req.r.rtm_protocol = 0; + req.r.rtm_scope = 0; + req.r.rtm_type = 0; + req.r.rtm_src_len = 0; + req.r.rtm_dst_len = 0; + req.r.rtm_tos = 0; + + addattr_l(&req.n, sizeof(req), RTA_DST, &dst.s_addr, 4); + req.r.rtm_dst_len = 32; + + ret = rtnl_open(&rth, 0); + + if (ret < 0 || rth.fd <= 0) + return ret; + + if (rtnl_talk(&rth, &req.n, 0, 0, &req.n, NULL, NULL) < 0) { + ret = -1; + goto close_rth; + } + + ret = find_dst(&req.n, src, gw); +close_rth: + rtnl_close(&rth); + return ret; +} + +#endif /* __linux__ */ |