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1 | /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ |
2 | ||
3 | /*** | |
4 | This file is part of nss-myhostname. | |
5 | ||
6 | Copyright 2008-2011 Lennart Poettering | |
7 | ||
8 | nss-myhostname is free software; you can redistribute it and/or | |
9 | modify it under the terms of the GNU Lesser General Public License | |
10 | as published by the Free Software Foundation; either version 2.1 of | |
11 | the License, or (at your option) any later version. | |
12 | ||
13 | nss-myhostname is distributed in the hope that it will be useful, | |
14 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
16 | Lesser General Public License for more details. | |
17 | ||
18 | You should have received a copy of the GNU Lesser General Public | |
19 | License along with nss-myhostname; If not, see | |
20 | <http://www.gnu.org/licenses/>. | |
21 | ***/ | |
22 | ||
23 | #include <sys/socket.h> | |
24 | #include <sys/un.h> | |
25 | #include <asm/types.h> | |
26 | #include <inttypes.h> | |
27 | #include <linux/netlink.h> | |
28 | #include <linux/rtnetlink.h> | |
29 | #include <string.h> | |
30 | #include <assert.h> | |
31 | #include <errno.h> | |
32 | #include <limits.h> | |
33 | #include <arpa/inet.h> | |
34 | #include <unistd.h> | |
35 | #include <inttypes.h> | |
36 | #include <stdlib.h> | |
37 | ||
38 | #include "netlink.h" | |
39 | ||
40 | static int address_compare(const void *_a, const void *_b) { | |
41 | const struct address *a = _a, *b = _b; | |
42 | ||
43 | /* Order lowest scope first, IPv4 before IPv6, lowest interface index first */ | |
44 | ||
45 | if (a->scope < b->scope) | |
46 | return -1; | |
47 | if (a->scope > b->scope) | |
48 | return 1; | |
49 | ||
50 | if (a->family == AF_INET && b->family == AF_INET6) | |
51 | return -1; | |
52 | if (a->family == AF_INET6 && b->family == AF_INET) | |
53 | return 1; | |
54 | ||
55 | if (a->ifindex < b->ifindex) | |
56 | return -1; | |
57 | if (a->ifindex > b->ifindex) | |
58 | return 1; | |
59 | ||
60 | return 0; | |
61 | } | |
62 | ||
63 | int netlink_acquire_addresses(struct address **_list, unsigned *_n_list) { | |
64 | ||
65 | struct { | |
66 | struct nlmsghdr hdr; | |
67 | struct rtgenmsg gen; | |
68 | } req; | |
69 | struct rtgenmsg *gen; | |
70 | int fd, r, on = 1; | |
71 | uint32_t seq = 4711; | |
72 | struct address *list = NULL; | |
73 | unsigned n_list = 0; | |
74 | ||
75 | fd = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE); | |
76 | if (fd < 0) | |
77 | return -errno; | |
78 | ||
79 | if (setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on)) < 0) { | |
80 | r = -errno; | |
81 | goto finish; | |
82 | } | |
83 | ||
84 | memset(&req, 0, sizeof(req)); | |
85 | req.hdr.nlmsg_len = NLMSG_LENGTH(sizeof(struct rtgenmsg)); | |
86 | req.hdr.nlmsg_type = RTM_GETADDR; | |
87 | req.hdr.nlmsg_flags = NLM_F_REQUEST|NLM_F_DUMP|NLM_F_ACK; | |
88 | req.hdr.nlmsg_seq = seq; | |
89 | req.hdr.nlmsg_pid = 0; | |
90 | ||
91 | gen = NLMSG_DATA(&req.hdr); | |
92 | gen->rtgen_family = AF_UNSPEC; | |
93 | ||
94 | if (send(fd, &req, req.hdr.nlmsg_len, 0) < 0) { | |
95 | r = -errno; | |
96 | goto finish; | |
97 | } | |
98 | ||
99 | for (;;) { | |
100 | ssize_t bytes; | |
101 | struct msghdr msg; | |
102 | struct cmsghdr *cmsg; | |
103 | struct ucred *ucred; | |
104 | struct iovec iov; | |
105 | struct nlmsghdr *p; | |
106 | uint8_t cred_buffer[CMSG_SPACE(sizeof(struct ucred))]; | |
107 | struct { | |
108 | struct nlmsghdr hdr; | |
109 | struct ifaddrmsg ifaddrmsg; | |
110 | uint8_t payload[16*1024]; | |
111 | } resp; | |
112 | ||
113 | memset(&iov, 0, sizeof(iov)); | |
114 | iov.iov_base = &resp; | |
115 | iov.iov_len = sizeof(resp); | |
116 | ||
117 | memset(&msg, 0, sizeof(msg)); | |
118 | msg.msg_name = NULL; | |
119 | msg.msg_namelen = 0; | |
120 | msg.msg_iov = &iov; | |
121 | msg.msg_iovlen = 1; | |
122 | msg.msg_control = cred_buffer; | |
123 | msg.msg_controllen = sizeof(cred_buffer); | |
124 | msg.msg_flags = 0; | |
125 | ||
126 | bytes = recvmsg(fd, &msg, 0); | |
127 | if (bytes < 0) { | |
128 | r = -errno; | |
129 | goto finish; | |
130 | } | |
131 | ||
132 | cmsg = CMSG_FIRSTHDR(&msg); | |
133 | if (!cmsg || cmsg->cmsg_type != SCM_CREDENTIALS) { | |
134 | r = -EIO; | |
135 | goto finish; | |
136 | } | |
137 | ||
138 | ucred = (struct ucred*) CMSG_DATA(cmsg); | |
139 | if (ucred->uid != 0 || ucred->pid != 0) | |
140 | continue; | |
141 | ||
142 | for (p = &resp.hdr; bytes > 0; p = NLMSG_NEXT(p, bytes)) { | |
143 | struct ifaddrmsg *ifaddrmsg; | |
144 | struct rtattr *a; | |
145 | size_t l; | |
146 | void *local = NULL, *address = NULL; | |
147 | ||
148 | if (!NLMSG_OK(p, (size_t) bytes)) { | |
149 | r = -EIO; | |
150 | goto finish; | |
151 | } | |
152 | ||
153 | if (p->nlmsg_seq != seq) | |
154 | continue; | |
155 | ||
156 | if (p->nlmsg_type == NLMSG_DONE) { | |
157 | r = 0; | |
158 | goto finish; | |
159 | } | |
160 | ||
161 | if (p->nlmsg_type == NLMSG_ERROR) { | |
162 | struct nlmsgerr *nlmsgerr; | |
163 | ||
164 | nlmsgerr = NLMSG_DATA(p); | |
165 | r = -nlmsgerr->error; | |
166 | goto finish; | |
167 | } | |
168 | ||
169 | if (p->nlmsg_type != RTM_NEWADDR) | |
170 | continue; | |
171 | ||
172 | ifaddrmsg = NLMSG_DATA(p); | |
173 | ||
174 | if (ifaddrmsg->ifa_family != AF_INET && | |
175 | ifaddrmsg->ifa_family != AF_INET6) | |
176 | continue; | |
177 | ||
178 | if (ifaddrmsg->ifa_scope == RT_SCOPE_HOST || | |
179 | ifaddrmsg->ifa_scope == RT_SCOPE_NOWHERE) | |
180 | continue; | |
181 | ||
182 | if (ifaddrmsg->ifa_flags & IFA_F_DEPRECATED) | |
183 | continue; | |
184 | ||
185 | l = NLMSG_PAYLOAD(p, sizeof(struct ifaddrmsg)); | |
186 | a = IFA_RTA(ifaddrmsg); | |
187 | ||
188 | while (RTA_OK(a, l)) { | |
189 | ||
190 | if (a->rta_type == IFA_ADDRESS) | |
191 | address = RTA_DATA(a); | |
192 | else if (a->rta_type == IFA_LOCAL) | |
193 | local = RTA_DATA(a); | |
194 | ||
195 | a = RTA_NEXT(a, l); | |
196 | } | |
197 | ||
198 | if (local) | |
199 | address = local; | |
200 | ||
201 | if (!address) | |
202 | continue; | |
203 | ||
204 | list = realloc(list, (n_list+1) * sizeof(struct address)); | |
205 | if (!list) { | |
206 | r = -ENOMEM; | |
207 | goto finish; | |
208 | } | |
209 | ||
210 | list[n_list].family = ifaddrmsg->ifa_family; | |
211 | list[n_list].scope = ifaddrmsg->ifa_scope; | |
212 | memcpy(list[n_list].address, address, ifaddrmsg->ifa_family == AF_INET ? 4 : 16); | |
213 | list[n_list].ifindex = ifaddrmsg->ifa_index; | |
214 | ||
215 | n_list++; | |
216 | } | |
217 | } | |
218 | ||
219 | finish: | |
220 | close(fd); | |
221 | ||
222 | if (r < 0) | |
223 | free(list); | |
224 | else { | |
225 | qsort(list, n_list, sizeof(struct address), address_compare); | |
226 | ||
227 | *_list = list; | |
228 | *_n_list = n_list; | |
229 | } | |
230 | ||
231 | return r; | |
232 | } |