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 <unistd.h> 25 #include <errno.h> 26 #include <string.h> 27 #include <sys/ioctl.h> 28 #include <assert.h> 29 30 #include "avahi-common/avahi-malloc.h" 31 #include "netlink.h" 32 #include "log.h" 33 34 struct AvahiNetlink { 35 int fd; 36 unsigned seq; 37 AvahiNetlinkCallback callback; 38 void* userdata; 39 uint8_t* buffer; 40 size_t buffer_length; 41 42 const AvahiPoll *poll_api; 43 AvahiWatch *watch; 44 }; 45 46 int avahi_netlink_work(AvahiNetlink *nl, int block) { 47 ssize_t bytes; 48 struct msghdr smsg; 49 struct cmsghdr *cmsg; 50 struct ucred *cred; 51 struct iovec iov; 52 struct nlmsghdr *p; 53 char cred_msg[CMSG_SPACE(sizeof(struct ucred))]; 54 55 assert(nl); 56 57 iov.iov_base = nl->buffer; 58 iov.iov_len = nl->buffer_length; 59 60 smsg.msg_name = NULL; 61 smsg.msg_namelen = 0; 62 smsg.msg_iov = &iov; 63 smsg.msg_iovlen = 1; 64 smsg.msg_control = cred_msg; 65 smsg.msg_controllen = sizeof(cred_msg); 66 smsg.msg_flags = (block ? 0 : MSG_DONTWAIT); 67 68 if ((bytes = recvmsg(nl->fd, &smsg, 0)) < 0) { 69 if (errno == EAGAIN || errno == EINTR) 70 return 0; 71 72 avahi_log_error(__FILE__": recvmsg() failed: %s", strerror(errno)); 73 return -1; 74 } 75 76 cmsg = CMSG_FIRSTHDR(&smsg); 77 78 if (!cmsg || cmsg->cmsg_type != SCM_CREDENTIALS) { 79 avahi_log_warn("No sender credentials received, ignoring data."); 80 return -1; 81 } 82 83 cred = (struct ucred*) CMSG_DATA(cmsg); 84 85 if (cred->uid != 0) 86 return -1; 87 88 p = (struct nlmsghdr *) nl->buffer; 89 90 assert(nl->callback); 91 92 for (; bytes > 0; p = NLMSG_NEXT(p, bytes)) { 93 if (!NLMSG_OK(p, (size_t) bytes)) { 94 avahi_log_warn(__FILE__": packet truncated"); 95 return -1; 96 } 97 98 nl->callback(nl, p, nl->userdata); 99 } 100 101 return 0; 102 } 103 104 static void socket_event(AvahiWatch *w, int fd, AVAHI_GCC_UNUSED AvahiWatchEvent event, void *userdata) { 105 AvahiNetlink *nl = userdata; 106 107 assert(w); 108 assert(nl); 109 assert(fd == nl->fd); 110 111 avahi_netlink_work(nl, 0); 112 } 113 114 AvahiNetlink *avahi_netlink_new(const AvahiPoll *poll_api, uint32_t groups, void (*cb) (AvahiNetlink *nl, struct nlmsghdr *n, void* userdata), void* userdata) { 115 int fd = -1; 116 const int on = 1; 117 struct sockaddr_nl addr; 118 AvahiNetlink *nl = NULL; 119 120 assert(poll_api); 121 assert(cb); 122 123 if ((fd = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE)) < 0) { 124 avahi_log_error(__FILE__": socket(PF_NETLINK): %s", strerror(errno)); 125 return NULL; 126 } 127 128 memset(&addr, 0, sizeof(addr)); 129 addr.nl_family = AF_NETLINK; 130 addr.nl_groups = groups; 131 addr.nl_pid = getpid(); 132 133 if (bind(fd, (struct sockaddr *) &addr, sizeof(addr)) < 0) { 134 avahi_log_error(__FILE__": bind(): %s", strerror(errno)); 135 goto fail; 136 } 137 138 if (setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on)) < 0) { 139 avahi_log_error(__FILE__": SO_PASSCRED: %s", strerror(errno)); 140 goto fail; 141 } 142 143 if (!(nl = avahi_new(AvahiNetlink, 1))) { 144 avahi_log_error(__FILE__": avahi_new() failed."); 145 goto fail; 146 } 147 148 nl->poll_api = poll_api; 149 nl->fd = fd; 150 nl->seq = 0; 151 nl->callback = cb; 152 nl->userdata = userdata; 153 154 if (!(nl->buffer = avahi_new(uint8_t, nl->buffer_length = 64*1024))) { 155 avahi_log_error(__FILE__": avahi_new() failed."); 156 goto fail; 157 } 158 159 if (!(nl->watch = poll_api->watch_new(poll_api, fd, AVAHI_WATCH_IN, socket_event, nl))) { 160 avahi_log_error(__FILE__": Failed to create watch."); 161 goto fail; 162 } 163 164 return nl; 165 166 fail: 167 168 if (fd >= 0) 169 close(fd); 170 171 if (nl) { 172 avahi_free(nl->buffer); 173 avahi_free(nl); 174 } 175 176 return NULL; 177 } 178 179 void avahi_netlink_free(AvahiNetlink *nl) { 180 assert(nl); 181 182 if (nl->watch) 183 nl->poll_api->watch_free(nl->watch); 184 185 if (nl->fd >= 0) 186 close(nl->fd); 187 188 avahi_free(nl->buffer); 189 avahi_free(nl); 190 } 191 192 int avahi_netlink_send(AvahiNetlink *nl, struct nlmsghdr *m, unsigned *ret_seq) { 193 assert(nl); 194 assert(m); 195 196 m->nlmsg_seq = nl->seq++; 197 m->nlmsg_flags |= NLM_F_ACK; 198 199 if (send(nl->fd, m, m->nlmsg_len, 0) < 0) { 200 avahi_log_error(__FILE__": send(): %s", strerror(errno)); 201 return -1; 202 } 203 204 if (ret_seq) 205 *ret_seq = m->nlmsg_seq; 206 207 return 0; 208 } 209
