1/* $Id$ */ 2 3/*** 4 This file is part of avahi. 5 6 avahi is free software; you can redistribute it and/or modify it 7 under the terms of the GNU Lesser General Public License as 8 published by the Free Software Foundation; either version 2.1 of the 9 License, or (at your option) any later version. 10 11 avahi is distributed in the hope that it will be useful, but WITHOUT 12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 13 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General 14 Public License for more details. 15 16 You should have received a copy of the GNU Lesser General Public 17 License along with avahi; if not, write to the Free Software 18 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 19 USA. 20***/ 21 22#ifdef HAVE_CONFIG_H 23#include <config.h> 24#endif 25 26#include <unistd.h> 27#include <errno.h> 28#include <string.h> 29#include <sys/ioctl.h> 30#include <assert.h> 31 32#include <avahi-common/malloc.h> 33#include "netlink.h" 34#include "log.h" 35 36struct AvahiNetlink { 37 int fd; 38 unsigned seq; 39 AvahiNetlinkCallback callback; 40 void* userdata; 41 uint8_t* buffer; 42 size_t buffer_length; 43 44 const AvahiPoll *poll_api; 45 AvahiWatch *watch; 46}; 47 48int avahi_netlink_work(AvahiNetlink *nl, int block) { 49 ssize_t bytes; 50 struct msghdr smsg; 51 struct cmsghdr *cmsg; 52 struct ucred *cred; 53 struct iovec iov; 54 struct nlmsghdr *p; 55 char cred_msg[CMSG_SPACE(sizeof(struct ucred))]; 56 57 assert(nl); 58 59 iov.iov_base = nl->buffer; 60 iov.iov_len = nl->buffer_length; 61 62 smsg.msg_name = NULL; 63 smsg.msg_namelen = 0; 64 smsg.msg_iov = &iov; 65 smsg.msg_iovlen = 1; 66 smsg.msg_control = cred_msg; 67 smsg.msg_controllen = sizeof(cred_msg); 68 smsg.msg_flags = (block ? 0 : MSG_DONTWAIT); 69 70 if ((bytes = recvmsg(nl->fd, &smsg, 0)) < 0) { 71 if (errno == EAGAIN || errno == EINTR) 72 return 0; 73 74 avahi_log_error(__FILE__": recvmsg() failed: %s", strerror(errno)); 75 return -1; 76 } 77 78 cmsg = CMSG_FIRSTHDR(&smsg); 79 80 if (!cmsg || cmsg->cmsg_type != SCM_CREDENTIALS) { 81 avahi_log_warn("No sender credentials received, ignoring data."); 82 return -1; 83 } 84 85 cred = (struct ucred*) CMSG_DATA(cmsg); 86 87 if (cred->uid != 0) 88 return -1; 89 90 p = (struct nlmsghdr *) nl->buffer; 91 92 assert(nl->callback); 93 94 for (; bytes > 0; p = NLMSG_NEXT(p, bytes)) { 95 if (!NLMSG_OK(p, (size_t) bytes)) { 96 avahi_log_warn(__FILE__": packet truncated"); 97 return -1; 98 } 99 100 nl->callback(nl, p, nl->userdata); 101 } 102 103 return 0; 104} 105 106static void socket_event(AvahiWatch *w, int fd, AVAHI_GCC_UNUSED AvahiWatchEvent event, void *userdata) { 107 AvahiNetlink *nl = userdata; 108 109 assert(w); 110 assert(nl); 111 assert(fd == nl->fd); 112 113 avahi_netlink_work(nl, 0); 114} 115 116AvahiNetlink *avahi_netlink_new(const AvahiPoll *poll_api, uint32_t groups, void (*cb) (AvahiNetlink *nl, struct nlmsghdr *n, void* userdata), void* userdata) { 117 int fd = -1; 118 const int on = 1; 119 struct sockaddr_nl addr; 120 AvahiNetlink *nl = NULL; 121 122 assert(poll_api); 123 assert(cb); 124 125 if ((fd = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE)) < 0) { 126 avahi_log_error(__FILE__": socket(PF_NETLINK): %s", strerror(errno)); 127 return NULL; 128 } 129 130 memset(&addr, 0, sizeof(addr)); 131 addr.nl_family = AF_NETLINK; 132 addr.nl_groups = groups; 133 addr.nl_pid = getpid(); 134 135 if (bind(fd, (struct sockaddr *) &addr, sizeof(addr)) < 0) { 136 avahi_log_error(__FILE__": bind(): %s", strerror(errno)); 137 goto fail; 138 } 139 140 if (setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on)) < 0) { 141 avahi_log_error(__FILE__": SO_PASSCRED: %s", strerror(errno)); 142 goto fail; 143 } 144 145 if (!(nl = avahi_new(AvahiNetlink, 1))) { 146 avahi_log_error(__FILE__": avahi_new() failed."); 147 goto fail; 148 } 149 150 nl->poll_api = poll_api; 151 nl->fd = fd; 152 nl->seq = 0; 153 nl->callback = cb; 154 nl->userdata = userdata; 155 156 if (!(nl->buffer = avahi_new(uint8_t, nl->buffer_length = 64*1024))) { 157 avahi_log_error(__FILE__": avahi_new() failed."); 158 goto fail; 159 } 160 161 if (!(nl->watch = poll_api->watch_new(poll_api, fd, AVAHI_WATCH_IN, socket_event, nl))) { 162 avahi_log_error(__FILE__": Failed to create watch."); 163 goto fail; 164 } 165 166 return nl; 167 168fail: 169 170 if (fd >= 0) 171 close(fd); 172 173 if (nl) { 174 avahi_free(nl->buffer); 175 avahi_free(nl); 176 } 177 178 return NULL; 179} 180 181void avahi_netlink_free(AvahiNetlink *nl) { 182 assert(nl); 183 184 if (nl->watch) 185 nl->poll_api->watch_free(nl->watch); 186 187 if (nl->fd >= 0) 188 close(nl->fd); 189 190 avahi_free(nl->buffer); 191 avahi_free(nl); 192} 193 194int avahi_netlink_send(AvahiNetlink *nl, struct nlmsghdr *m, unsigned *ret_seq) { 195 assert(nl); 196 assert(m); 197 198 m->nlmsg_seq = nl->seq++; 199 m->nlmsg_flags |= NLM_F_ACK; 200 201 if (send(nl->fd, m, m->nlmsg_len, 0) < 0) { 202 avahi_log_error(__FILE__": send(): %s", strerror(errno)); 203 return -1; 204 } 205 206 if (ret_seq) 207 *ret_seq = m->nlmsg_seq; 208 209 return 0; 210} 211