1 /*** 2 This file is part of avahi. 3 4 avahi is free software; you can redistribute it and/or modify it 5 under the terms of the GNU Lesser General Public License as 6 published by the Free Software Foundation; either version 2.1 of the 7 License, or (at your option) any later version. 8 9 avahi is distributed in the hope that it will be useful, but WITHOUT 10 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 11 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General 12 Public License for more details. 13 14 You should have received a copy of the GNU Lesser General Public 15 License along with avahi; if not, write to the Free Software 16 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 17 USA. 18 ***/ 19 20 #ifdef HAVE_CONFIG_H 21 #include <config.h> 22 #endif 23 24 #include <sys/socket.h> 25 #include <errno.h> 26 #include <string.h> 27 #include <unistd.h> 28 #include <arpa/inet.h> 29 30 #include <linux/types.h> 31 #include <linux/netlink.h> 32 #include <linux/rtnetlink.h> 33 #include <linux/if.h> 34 #include <linux/if_arp.h> 35 36 #include <libdaemon/dlog.h> 37 38 #include <avahi-common/llist.h> 39 #include "avahi-common/avahi-malloc.h" 40 41 #ifndef IFLA_RTA 42 #include <linux/if_addr.h> 43 #define IFLA_RTA(r) ((struct rtattr*)(((char*)(r)) + NLMSG_ALIGN(sizeof(struct ifinfomsg)))) 44 #endif 45 46 #ifndef IFA_RTA 47 #include <linux/if_addr.h> 48 #define IFA_RTA(r) ((struct rtattr*)(((char*)(r)) + NLMSG_ALIGN(sizeof(struct ifaddrmsg)))) 49 #endif 50 51 #include "iface.h" 52 53 static int fd = -1; 54 static int ifindex = -1; 55 56 typedef struct Address Address; 57 58 struct Address { 59 uint32_t address; 60 AVAHI_LLIST_FIELDS(Address, addresses); 61 }; 62 63 AVAHI_LLIST_HEAD(Address, addresses) = NULL; 64 65 int iface_init(int i) { 66 struct sockaddr_nl addr; 67 int on = 1; 68 69 if ((fd = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE)) < 0) { 70 daemon_log(LOG_ERR, "socket(PF_NETLINK): %s", strerror(errno)); 71 goto fail; 72 } 73 74 memset(&addr, 0, sizeof(addr)); 75 addr.nl_family = AF_NETLINK; 76 addr.nl_groups = RTMGRP_LINK|RTMGRP_IPV4_IFADDR; 77 addr.nl_pid = getpid(); 78 79 if (bind(fd, (struct sockaddr *) &addr, sizeof(addr)) < 0) { 80 daemon_log(LOG_ERR, "bind(): %s", strerror(errno)); 81 goto fail; 82 } 83 84 if (setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on)) < 0) { 85 daemon_log(LOG_ERR, "SO_PASSCRED: %s", strerror(errno)); 86 goto fail; 87 } 88 89 ifindex = i; 90 91 return fd; 92 93 fail: 94 if (fd >= 0) { 95 close(fd); 96 fd = -1; 97 } 98 99 return -1; 100 } 101 102 static int process_nlmsg(struct nlmsghdr *n) { 103 assert(n); 104 105 if (n->nlmsg_type == RTM_NEWLINK || n->nlmsg_type == RTM_DELLINK) { 106 /* A link appeared or was removed */ 107 108 struct ifinfomsg *ifi; 109 ifi = NLMSG_DATA(n); 110 111 if (ifi->ifi_family != AF_UNSPEC || (int) ifi->ifi_index != ifindex) 112 return 0; 113 114 if (n->nlmsg_type == RTM_DELLINK) { 115 daemon_log(LOG_ERR, "Interface vanished."); 116 return -1; 117 } 118 119 assert(n->nlmsg_type == RTM_NEWLINK); 120 121 if ((ifi->ifi_flags & IFF_LOOPBACK) || 122 (ifi->ifi_flags & IFF_NOARP) || 123 ifi->ifi_type != ARPHRD_ETHER) { 124 daemon_log(LOG_ERR, "Interface not suitable."); 125 return -1; 126 } 127 128 } else if (n->nlmsg_type == RTM_NEWADDR || n->nlmsg_type == RTM_DELADDR) { 129 130 /* An address was added or removed */ 131 132 struct rtattr *a = NULL; 133 struct ifaddrmsg *ifa; 134 int l; 135 uint32_t address = 0; 136 Address *i; 137 138 ifa = NLMSG_DATA(n); 139 140 if (ifa->ifa_family != AF_INET || (int) ifa->ifa_index != ifindex) 141 return 0; 142 143 l = NLMSG_PAYLOAD(n, sizeof(*ifa)); 144 a = IFLA_RTA(ifa); 145 146 while(RTA_OK(a, l)) { 147 148 switch(a->rta_type) { 149 case IFA_LOCAL: 150 case IFA_ADDRESS: 151 assert(RTA_PAYLOAD(a) == 4); 152 memcpy(&address, RTA_DATA(a), sizeof(uint32_t)); 153 break; 154 } 155 156 a = RTA_NEXT(a, l); 157 } 158 159 if (!address || is_ll_address(address)) 160 return 0; 161 162 for (i = addresses; i; i = i->addresses_next) 163 if (i->address == address) 164 break; 165 166 if (n->nlmsg_type == RTM_DELADDR && i) { 167 AVAHI_LLIST_REMOVE(Address, addresses, addresses, i); 168 avahi_free(i); 169 } if (n->nlmsg_type == RTM_NEWADDR && !i) { 170 i = avahi_new(Address, 1); 171 i->address = address; 172 AVAHI_LLIST_PREPEND(Address, addresses, addresses, i); 173 } 174 } 175 176 return 0; 177 } 178 179 static int process_response(int wait_for_done, unsigned seq) { 180 assert(fd >= 0); 181 182 do { 183 size_t bytes; 184 ssize_t r; 185 char replybuf[8*1024]; 186 char cred_msg[CMSG_SPACE(sizeof(struct ucred))]; 187 struct msghdr msghdr; 188 struct cmsghdr *cmsghdr; 189 struct ucred *ucred; 190 struct iovec iov; 191 struct nlmsghdr *p = (struct nlmsghdr *) replybuf; 192 193 memset(&iov, 0, sizeof(iov)); 194 iov.iov_base = replybuf; 195 iov.iov_len = sizeof(replybuf); 196 197 memset(&msghdr, 0, sizeof(msghdr)); 198 msghdr.msg_name = (void*) NULL; 199 msghdr.msg_namelen = 0; 200 msghdr.msg_iov = &iov; 201 msghdr.msg_iovlen = 1; 202 msghdr.msg_control = cred_msg; 203 msghdr.msg_controllen = sizeof(cred_msg); 204 msghdr.msg_flags = 0; 205 206 if ((r = recvmsg(fd, &msghdr, 0)) < 0) { 207 daemon_log(LOG_ERR, "recvmsg() failed: %s", strerror(errno)); 208 return -1; 209 } 210 211 if (!(cmsghdr = CMSG_FIRSTHDR(&msghdr)) || cmsghdr->cmsg_type != SCM_CREDENTIALS) { 212 daemon_log(LOG_WARNING, "No sender credentials received, ignoring data."); 213 return -1; 214 } 215 216 ucred = (struct ucred*) CMSG_DATA(cmsghdr); 217 218 if (ucred->uid != 0) 219 return -1; 220 221 bytes = (size_t) r; 222 223 for (; bytes > 0; p = NLMSG_NEXT(p, bytes)) { 224 225 if (!NLMSG_OK(p, bytes) || bytes < sizeof(struct nlmsghdr) || bytes < p->nlmsg_len) { 226 daemon_log(LOG_ERR, "Netlink packet too small."); 227 return -1; 228 } 229 230 if (p->nlmsg_type == NLMSG_DONE && wait_for_done && p->nlmsg_seq == seq && (pid_t) p->nlmsg_pid == getpid()) 231 return 0; 232 233 if (p->nlmsg_type == NLMSG_ERROR) { 234 struct nlmsgerr *e = (struct nlmsgerr *) NLMSG_DATA (p); 235 236 if (e->error) { 237 daemon_log(LOG_ERR, "Netlink error: %s", strerror(-e->error)); 238 return -1; 239 } 240 } 241 242 if (process_nlmsg(p) < 0) 243 return -1; 244 } 245 } while (wait_for_done); 246 247 return 0; 248 } 249 250 int iface_get_initial_state(State *state) { 251 struct nlmsghdr *n; 252 struct ifinfomsg *ifi; 253 struct ifaddrmsg *ifa; 254 uint8_t req[1024]; 255 int seq = 0; 256 257 assert(fd >= 0); 258 assert(state); 259 260 memset(&req, 0, sizeof(req)); 261 n = (struct nlmsghdr*) req; 262 n->nlmsg_len = NLMSG_LENGTH(sizeof(*ifi)); 263 n->nlmsg_type = RTM_GETLINK; 264 n->nlmsg_seq = seq; 265 n->nlmsg_flags = NLM_F_REQUEST|NLM_F_DUMP; 266 n->nlmsg_pid = 0; 267 268 ifi = NLMSG_DATA(n); 269 ifi->ifi_family = AF_UNSPEC; 270 ifi->ifi_change = -1; 271 272 if (send(fd, n, n->nlmsg_len, 0) < 0) { 273 daemon_log(LOG_ERR, "send(): %s", strerror(errno)); 274 return -1; 275 } 276 277 if (process_response(1, 0) < 0) 278 return -1; 279 280 n->nlmsg_type = RTM_GETADDR; 281 n->nlmsg_len = NLMSG_LENGTH(sizeof(*ifa)); 282 n->nlmsg_seq = ++seq; 283 284 ifa = NLMSG_DATA(n); 285 ifa->ifa_family = AF_INET; 286 ifa->ifa_index = ifindex; 287 288 if (send(fd, n, n->nlmsg_len, 0) < 0) { 289 daemon_log(LOG_ERR, "send(): %s", strerror(errno)); 290 return -1; 291 } 292 293 if (process_response(1, seq) < 0) 294 return -1; 295 296 *state = addresses ? STATE_SLEEPING : STATE_START; 297 298 return 0; 299 } 300 301 int iface_process(Event *event) { 302 int b; 303 assert(fd >= 0); 304 305 b = !!addresses; 306 307 if (process_response(0, 0) < 0) 308 return -1; 309 310 if (b && !addresses) 311 *event = EVENT_ROUTABLE_ADDR_UNCONFIGURED; 312 else if (!b && addresses) 313 *event = EVENT_ROUTABLE_ADDR_CONFIGURED; 314 315 return 0; 316 } 317 318 void iface_done(void) { 319 Address *a; 320 321 if (fd >= 0) { 322 close(fd); 323 fd = -1; 324 } 325 326 while ((a = addresses)) { 327 AVAHI_LLIST_REMOVE(Address, addresses, addresses, a); 328 avahi_free(a); 329 } 330 } 331 332 333
