diff options
Diffstat (limited to 'netlink.c')
| -rw-r--r-- | netlink.c | 232 |
1 files changed, 232 insertions, 0 deletions
diff --git a/netlink.c b/netlink.c new file mode 100644 index 0000000..e7a3863 --- /dev/null +++ b/netlink.c @@ -0,0 +1,232 @@ +/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ + +/*** + This file is part of nss-myhostname. + + Copyright 2008-2011 Lennart Poettering + + nss-myhostname 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. + + nss-myhostname 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 nss-myhostname; If not, see + <http://www.gnu.org/licenses/>. +***/ + +#include <sys/socket.h> +#include <sys/un.h> +#include <asm/types.h> +#include <inttypes.h> +#include <linux/netlink.h> +#include <linux/rtnetlink.h> +#include <string.h> +#include <assert.h> +#include <errno.h> +#include <limits.h> +#include <arpa/inet.h> +#include <unistd.h> +#include <inttypes.h> +#include <stdlib.h> + +#include "netlink.h" + +static int address_compare(const void *_a, const void *_b) { + const struct address *a = _a, *b = _b; + + /* Order lowest scope first, IPv4 before IPv6, lowest interface index first */ + + if (a->scope < b->scope) + return -1; + if (a->scope > b->scope) + return 1; + + if (a->family == AF_INET && b->family == AF_INET6) + return -1; + if (a->family == AF_INET6 && b->family == AF_INET) + return 1; + + if (a->ifindex < b->ifindex) + return -1; + if (a->ifindex > b->ifindex) + return 1; + + return 0; +} + +int netlink_acquire_addresses(struct address **_list, unsigned *_n_list) { + + struct { + struct nlmsghdr hdr; + struct rtgenmsg gen; + } req; + struct rtgenmsg *gen; + int fd, r, on = 1; + uint32_t seq = 4711; + struct address *list = NULL; + unsigned n_list = 0; + + fd = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE); + if (fd < 0) + return -errno; + + if (setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on)) < 0) { + r = -errno; + goto finish; + } + + memset(&req, 0, sizeof(req)); + req.hdr.nlmsg_len = NLMSG_LENGTH(sizeof(struct rtgenmsg)); + req.hdr.nlmsg_type = RTM_GETADDR; + req.hdr.nlmsg_flags = NLM_F_REQUEST|NLM_F_DUMP|NLM_F_ACK; + req.hdr.nlmsg_seq = seq; + req.hdr.nlmsg_pid = 0; + + gen = NLMSG_DATA(&req.hdr); + gen->rtgen_family = AF_UNSPEC; + + if (send(fd, &req, req.hdr.nlmsg_len, 0) < 0) { + r = -errno; + goto finish; + } + + for (;;) { + ssize_t bytes; + struct msghdr msg; + struct cmsghdr *cmsg; + struct ucred *ucred; + struct iovec iov; + struct nlmsghdr *p; + uint8_t cred_buffer[CMSG_SPACE(sizeof(struct ucred))]; + struct { + struct nlmsghdr hdr; + struct ifaddrmsg ifaddrmsg; + uint8_t payload[16*1024]; + } resp; + + memset(&iov, 0, sizeof(iov)); + iov.iov_base = &resp; + iov.iov_len = sizeof(resp); + + memset(&msg, 0, sizeof(msg)); + msg.msg_name = NULL; + msg.msg_namelen = 0; + msg.msg_iov = &iov; + msg.msg_iovlen = 1; + msg.msg_control = cred_buffer; + msg.msg_controllen = sizeof(cred_buffer); + msg.msg_flags = 0; + + bytes = recvmsg(fd, &msg, 0); + if (bytes < 0) { + r = -errno; + goto finish; + } + + cmsg = CMSG_FIRSTHDR(&msg); + if (!cmsg || cmsg->cmsg_type != SCM_CREDENTIALS) { + r = -EIO; + goto finish; + } + + ucred = (struct ucred*) CMSG_DATA(cmsg); + if (ucred->uid != 0 || ucred->pid != 0) + continue; + + for (p = &resp.hdr; bytes > 0; p = NLMSG_NEXT(p, bytes)) { + struct ifaddrmsg *ifaddrmsg; + struct rtattr *a; + size_t l; + void *local = NULL, *address = NULL; + + if (!NLMSG_OK(p, (size_t) bytes)) { + r = -EIO; + goto finish; + } + + if (p->nlmsg_seq != seq) + continue; + + if (p->nlmsg_type == NLMSG_DONE) { + r = 0; + goto finish; + } + + if (p->nlmsg_type == NLMSG_ERROR) { + struct nlmsgerr *nlmsgerr; + + nlmsgerr = NLMSG_DATA(p); + r = -nlmsgerr->error; + goto finish; + } + + if (p->nlmsg_type != RTM_NEWADDR) + continue; + + ifaddrmsg = NLMSG_DATA(p); + + if (ifaddrmsg->ifa_family != AF_INET && + ifaddrmsg->ifa_family != AF_INET6) + continue; + + if (ifaddrmsg->ifa_scope == RT_SCOPE_HOST || + ifaddrmsg->ifa_scope == RT_SCOPE_NOWHERE) + continue; + + if (ifaddrmsg->ifa_flags & IFA_F_DEPRECATED) + continue; + + l = NLMSG_PAYLOAD(p, sizeof(struct ifaddrmsg)); + a = IFA_RTA(ifaddrmsg); + + while (RTA_OK(a, l)) { + + if (a->rta_type == IFA_ADDRESS) + address = RTA_DATA(a); + else if (a->rta_type == IFA_LOCAL) + local = RTA_DATA(a); + + a = RTA_NEXT(a, l); + } + + if (local) + address = local; + + if (!address) + continue; + + list = realloc(list, (n_list+1) * sizeof(struct address)); + if (!list) { + r = -ENOMEM; + goto finish; + } + + list[n_list].family = ifaddrmsg->ifa_family; + list[n_list].scope = ifaddrmsg->ifa_scope; + memcpy(list[n_list].address, address, ifaddrmsg->ifa_family == AF_INET ? 4 : 16); + list[n_list].ifindex = ifaddrmsg->ifa_index; + + n_list++; + } + } + +finish: + close(fd); + + if (r < 0) + free(list); + else { + qsort(list, n_list, sizeof(struct address), address_compare); + + *_list = list; + *_n_list = n_list; + } + + return r; +} |