1/* 2 * libnetlink.c RTnetlink service routines. 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU General Public License 6 * as published by the Free Software Foundation; either version 7 * 2 of the License, or (at your option) any later version. 8 * 9 * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru> 10 * 11 */ 12 13#include <stdio.h> 14#include <stdlib.h> 15#include <unistd.h> 16#include <syslog.h> 17#include <fcntl.h> 18#include <net/if_arp.h> 19#include <sys/socket.h> 20#include <netinet/in.h> 21#include <string.h> 22#include <errno.h> 23#include <time.h> 24#include <sys/uio.h> 25 26#include "libnetlink.h" 27 28void rtnl_close(struct rtnl_handle *rth) 29{ 30 close(rth->fd); 31} 32 33int rtnl_send(struct rtnl_handle * rth, const char * buf, int len) 34{ 35 struct sockaddr_nl nladdr; 36 37 memset(&nladdr, 0, sizeof(nladdr)); 38 nladdr.nl_family = AF_NETLINK; 39 40 return sendto(rth->fd, buf, len, 0, (struct sockaddr*)&nladdr, sizeof(nladdr)); 41} 42 43int rtnl_open(struct rtnl_handle * rth, unsigned subscriptions) 44{ 45 int addr_len; 46 47 memset(rth, 0, sizeof(rth)); 48 49 rth->fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE); 50 51 if (rth->fd < 0) 52 return -1; 53 54 memset(&rth->local, 0, sizeof(rth->local)); 55 rth->local.nl_family = AF_NETLINK; 56 rth->local.nl_groups = subscriptions; 57 58 if (bind(rth->fd, (struct sockaddr*)&rth->local, sizeof(rth->local)) < 0) 59 return -1; 60 61 addr_len = sizeof(rth->local); 62 if (getsockname(rth->fd, (struct sockaddr*)&rth->local, &addr_len) < 0) 63 return -1; 64 65 if (addr_len != sizeof(rth->local)) 66 return -1; 67 68 if (rth->local.nl_family != AF_NETLINK) 69 return -1; 70 71 rth->seq = time(NULL); 72 73 return 0; 74} 75 76int rtnl_request(struct rtnl_handle * rth, int family, int type) 77{ 78 struct { 79 struct nlmsghdr nlh; 80 struct rtgenmsg g; 81 } req; 82 struct sockaddr_nl nladdr; 83 84 memset(&nladdr, 0, sizeof(nladdr)); 85 nladdr.nl_family = AF_NETLINK; 86 87 memset(&req, 0, sizeof(req)); 88 req.nlh.nlmsg_len = sizeof(req); 89 req.nlh.nlmsg_type = type; 90 req.nlh.nlmsg_flags = NLM_F_ROOT | NLM_F_MATCH |NLM_F_REQUEST; 91 req.nlh.nlmsg_pid = 0; 92 req.nlh.nlmsg_seq = rth->dump = ++rth->seq; 93 req.g.rtgen_family = family; 94 95 return sendto(rth->fd, (void*)&req, sizeof(req), 0, (struct sockaddr*)&nladdr, sizeof(nladdr)); 96} 97 98int rtnl_filter(struct rtnl_handle * rth, rtnl_filter_t filter, void * arg) 99{ 100 struct sockaddr_nl nladdr; 101 struct iovec iov; 102 struct msghdr msg = { 103 .msg_name = &nladdr, 104 .msg_namelen = sizeof(nladdr), 105 .msg_iov = &iov, 106 .msg_iovlen = 1, 107 }; 108 109 char buf[8192]; 110 111 iov.iov_base = buf; 112 113 while (1) { 114 int status; 115 struct nlmsghdr *h; 116 117 iov.iov_len = sizeof(buf); 118 status = recvmsg(rth->fd, &msg, 0); 119 120 if (status < 0) 121 continue; 122 123 if (status == 0) 124 return -1; 125 126 h = (struct nlmsghdr*)buf; 127 while (NLMSG_OK(h, status)) { 128 int err; 129 130 if (nladdr.nl_pid != 0 || h->nlmsg_pid != rth->local.nl_pid || h->nlmsg_seq != rth->dump) 131 goto skip_it; 132 133 if (h->nlmsg_type == NLMSG_DONE) 134 return 0; 135 136 if (h->nlmsg_type == NLMSG_ERROR) 137 return -1; 138 139 err = filter(&nladdr, h, arg); 140 141 if (err < 0) 142 return err; 143 144skip_it: 145 h = NLMSG_NEXT(h, status); 146 } 147 148 if (msg.msg_flags & MSG_TRUNC) 149 continue; 150 151 if (status) 152 return -1; 153 } 154} 155 156int rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n, pid_t peer, unsigned groups, struct nlmsghdr *answer) 157{ 158 int status; 159 unsigned seq; 160 struct nlmsghdr *h; 161 struct sockaddr_nl nladdr; 162 struct iovec iov = { 163 .iov_base = (void*) n, 164 .iov_len = n->nlmsg_len 165 }; 166 struct msghdr msg = { 167 .msg_name = &nladdr, 168 .msg_namelen = sizeof(nladdr), 169 .msg_iov = &iov, 170 .msg_iovlen = 1, 171 }; 172 173 char buf[8192]; 174 175 memset(&nladdr, 0, sizeof(nladdr)); 176 nladdr.nl_family = AF_NETLINK; 177 nladdr.nl_pid = peer; 178 nladdr.nl_groups = groups; 179 180 n->nlmsg_seq = seq = ++rtnl->seq; 181 182 if (answer == NULL) 183 n->nlmsg_flags |= NLM_F_ACK; 184 185 status = sendmsg(rtnl->fd, &msg, 0); 186 187 if (status < 0) { 188 perror("Can't talk to rtnetlink"); 189 return -1; 190 } 191 192 memset(buf,0,sizeof(buf)); 193 194 iov.iov_base = buf; 195 196 while (1) { 197 iov.iov_len = sizeof(buf); 198 status = recvmsg(rtnl->fd, &msg, 0); 199 200 if (status < 0) 201 continue; 202 203 if (status == 0) 204 return -1; 205 206 if (msg.msg_namelen != sizeof(nladdr)) 207 return -1; 208 209 for (h = (struct nlmsghdr*)buf; status >= sizeof(*h); ) { 210 int len = h->nlmsg_len; 211 int l = len - sizeof(*h); 212 213 if (l<0 || len>status) 214 return -1; 215 216 if (nladdr.nl_pid != peer || h->nlmsg_pid != rtnl->local.nl_pid || h->nlmsg_seq != seq) 217 continue; 218 219 if (h->nlmsg_type == NLMSG_ERROR) 220 return -1; 221 222 if (answer) { 223 memcpy(answer, h, h->nlmsg_len); 224 return 0; 225 } 226 227 fprintf(stderr, "Unexpected reply!!!\n"); 228 229 status -= NLMSG_ALIGN(len); 230 h = (struct nlmsghdr*)((char*)h + NLMSG_ALIGN(len)); 231 } 232 233 if (msg.msg_flags & MSG_TRUNC) 234 continue; 235 236 if (status) 237 return -1; 238 } 239} 240 241int addattr32(struct nlmsghdr *n, int maxlen, int type, unsigned int data) 242{ 243 int len = RTA_LENGTH(4); 244 struct rtattr *rta; 245 246 if (NLMSG_ALIGN(n->nlmsg_len) + len > maxlen) 247 return -1; 248 249 rta = NLMSG_TAIL(n); 250 rta->rta_type = type; 251 rta->rta_len = len; 252 253 memcpy(RTA_DATA(rta), &data, 4); 254 n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + len; 255 256 return 0; 257} 258 259int addattr_l(struct nlmsghdr *n, int maxlen, int type, const void *data, int alen) 260{ 261 int len = RTA_LENGTH(alen); 262 struct rtattr *rta; 263 264 if (NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(len) > maxlen) 265 return -1; 266 267 rta = NLMSG_TAIL(n); 268 rta->rta_type = type; 269 rta->rta_len = len; 270 271 memcpy(RTA_DATA(rta), data, alen); 272 273 n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(len); 274 275 return 0; 276} 277 278int parse_rtattr(struct rtattr * tb[], int max, struct rtattr * rta, int len) 279{ 280 memset(tb, 0, sizeof(struct rtattr *) * (max + 1)); 281 282 while (RTA_OK(rta, len)) { 283 if (rta->rta_type <= max) 284 tb[rta->rta_type] = rta; 285 286 rta = RTA_NEXT(rta,len); 287 } 288 289 return 0; 290} 291 292