332 lines
8.2 KiB
C
332 lines
8.2 KiB
C
/***
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This file is part of avahi.
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avahi is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation; either version 2.1 of the
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License, or (at your option) any later version.
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avahi is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
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Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with avahi; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
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USA.
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***/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif
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#include <sys/socket.h>
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#include <errno.h>
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#include <string.h>
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#include <unistd.h>
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#include <arpa/inet.h>
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#include <linux/types.h>
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#include <linux/netlink.h>
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#include <linux/rtnetlink.h>
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#include <linux/if.h>
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#include <linux/if_arp.h>
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#include <libdaemon/dlog.h>
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#include <avahi-common/llist.h>
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#include "avahi-common/avahi-malloc.h"
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#ifndef IFLA_RTA
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#include <linux/if_addr.h>
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#define IFLA_RTA(r) ((struct rtattr*)(((char*)(r)) + NLMSG_ALIGN(sizeof(struct ifinfomsg))))
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#endif
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#ifndef IFA_RTA
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#include <linux/if_addr.h>
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#define IFA_RTA(r) ((struct rtattr*)(((char*)(r)) + NLMSG_ALIGN(sizeof(struct ifaddrmsg))))
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#endif
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#include "iface.h"
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static int fd = -1;
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static int ifindex = -1;
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typedef struct Address Address;
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struct Address {
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uint32_t address;
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AVAHI_LLIST_FIELDS(Address, addresses);
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};
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AVAHI_LLIST_HEAD(Address, addresses) = NULL;
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int iface_init(int i) {
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struct sockaddr_nl addr;
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int on = 1;
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if ((fd = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE)) < 0) {
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daemon_log(LOG_ERR, "socket(PF_NETLINK): %s", strerror(errno));
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goto fail;
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}
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memset(&addr, 0, sizeof(addr));
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addr.nl_family = AF_NETLINK;
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addr.nl_groups = RTMGRP_LINK|RTMGRP_IPV4_IFADDR;
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addr.nl_pid = getpid();
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if (bind(fd, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
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daemon_log(LOG_ERR, "bind(): %s", strerror(errno));
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goto fail;
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}
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if (setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on)) < 0) {
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daemon_log(LOG_ERR, "SO_PASSCRED: %s", strerror(errno));
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goto fail;
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}
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ifindex = i;
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return fd;
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fail:
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if (fd >= 0) {
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close(fd);
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fd = -1;
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}
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return -1;
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}
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static int process_nlmsg(struct nlmsghdr *n) {
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assert(n);
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if (n->nlmsg_type == RTM_NEWLINK || n->nlmsg_type == RTM_DELLINK) {
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/* A link appeared or was removed */
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struct ifinfomsg *ifi;
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ifi = NLMSG_DATA(n);
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if (ifi->ifi_family != AF_UNSPEC || (int) ifi->ifi_index != ifindex)
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return 0;
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if (n->nlmsg_type == RTM_DELLINK) {
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daemon_log(LOG_ERR, "Interface vanished.");
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return -1;
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}
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assert(n->nlmsg_type == RTM_NEWLINK);
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if ((ifi->ifi_flags & IFF_LOOPBACK) ||
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(ifi->ifi_flags & IFF_NOARP) ||
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ifi->ifi_type != ARPHRD_ETHER) {
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daemon_log(LOG_ERR, "Interface not suitable.");
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return -1;
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}
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} else if (n->nlmsg_type == RTM_NEWADDR || n->nlmsg_type == RTM_DELADDR) {
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/* An address was added or removed */
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struct rtattr *a = NULL;
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struct ifaddrmsg *ifa;
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int l;
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uint32_t address = 0;
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Address *i;
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ifa = NLMSG_DATA(n);
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if (ifa->ifa_family != AF_INET || (int) ifa->ifa_index != ifindex)
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return 0;
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l = NLMSG_PAYLOAD(n, sizeof(*ifa));
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a = IFLA_RTA(ifa);
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while(RTA_OK(a, l)) {
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switch(a->rta_type) {
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case IFA_LOCAL:
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case IFA_ADDRESS:
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assert(RTA_PAYLOAD(a) == 4);
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memcpy(&address, RTA_DATA(a), sizeof(uint32_t));
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break;
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}
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a = RTA_NEXT(a, l);
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}
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if (!address || is_ll_address(address))
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return 0;
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for (i = addresses; i; i = i->addresses_next)
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if (i->address == address)
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break;
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if (n->nlmsg_type == RTM_DELADDR && i) {
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AVAHI_LLIST_REMOVE(Address, addresses, addresses, i);
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avahi_free(i);
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} if (n->nlmsg_type == RTM_NEWADDR && !i) {
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i = avahi_new(Address, 1);
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i->address = address;
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AVAHI_LLIST_PREPEND(Address, addresses, addresses, i);
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}
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}
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return 0;
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}
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static int process_response(int wait_for_done, unsigned seq) {
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assert(fd >= 0);
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do {
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size_t bytes;
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ssize_t r;
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char replybuf[8*1024];
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char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
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struct msghdr msghdr;
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struct cmsghdr *cmsghdr;
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struct ucred *ucred;
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struct iovec iov;
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struct nlmsghdr *p = (struct nlmsghdr *) replybuf;
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memset(&iov, 0, sizeof(iov));
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iov.iov_base = replybuf;
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iov.iov_len = sizeof(replybuf);
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memset(&msghdr, 0, sizeof(msghdr));
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msghdr.msg_name = (void*) NULL;
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msghdr.msg_namelen = 0;
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msghdr.msg_iov = &iov;
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msghdr.msg_iovlen = 1;
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msghdr.msg_control = cred_msg;
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msghdr.msg_controllen = sizeof(cred_msg);
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msghdr.msg_flags = 0;
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if ((r = recvmsg(fd, &msghdr, 0)) < 0) {
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daemon_log(LOG_ERR, "recvmsg() failed: %s", strerror(errno));
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return -1;
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}
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if (!(cmsghdr = CMSG_FIRSTHDR(&msghdr)) || cmsghdr->cmsg_type != SCM_CREDENTIALS) {
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daemon_log(LOG_WARNING, "No sender credentials received, ignoring data.");
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return -1;
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}
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ucred = (struct ucred*) CMSG_DATA(cmsghdr);
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if (ucred->uid != 0)
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return -1;
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bytes = (size_t) r;
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for (; bytes > 0; p = NLMSG_NEXT(p, bytes)) {
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if (!NLMSG_OK(p, bytes) || bytes < sizeof(struct nlmsghdr) || bytes < p->nlmsg_len) {
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daemon_log(LOG_ERR, "Netlink packet too small.");
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return -1;
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}
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if (p->nlmsg_type == NLMSG_DONE && wait_for_done && p->nlmsg_seq == seq && (pid_t) p->nlmsg_pid == getpid())
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return 0;
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if (p->nlmsg_type == NLMSG_ERROR) {
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struct nlmsgerr *e = (struct nlmsgerr *) NLMSG_DATA (p);
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if (e->error) {
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daemon_log(LOG_ERR, "Netlink error: %s", strerror(-e->error));
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return -1;
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}
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}
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if (process_nlmsg(p) < 0)
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return -1;
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}
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} while (wait_for_done);
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return 0;
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}
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int iface_get_initial_state(State *state) {
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struct nlmsghdr *n;
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struct ifinfomsg *ifi;
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struct ifaddrmsg *ifa;
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uint8_t req[1024];
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int seq = 0;
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assert(fd >= 0);
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assert(state);
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memset(&req, 0, sizeof(req));
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n = (struct nlmsghdr*) req;
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n->nlmsg_len = NLMSG_LENGTH(sizeof(*ifi));
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n->nlmsg_type = RTM_GETLINK;
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n->nlmsg_seq = seq;
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n->nlmsg_flags = NLM_F_REQUEST|NLM_F_DUMP;
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n->nlmsg_pid = 0;
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ifi = NLMSG_DATA(n);
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ifi->ifi_family = AF_UNSPEC;
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ifi->ifi_change = -1;
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if (send(fd, n, n->nlmsg_len, 0) < 0) {
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daemon_log(LOG_ERR, "send(): %s", strerror(errno));
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return -1;
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}
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if (process_response(1, 0) < 0)
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return -1;
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n->nlmsg_type = RTM_GETADDR;
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n->nlmsg_len = NLMSG_LENGTH(sizeof(*ifa));
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n->nlmsg_seq = ++seq;
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ifa = NLMSG_DATA(n);
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ifa->ifa_family = AF_INET;
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ifa->ifa_index = ifindex;
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if (send(fd, n, n->nlmsg_len, 0) < 0) {
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daemon_log(LOG_ERR, "send(): %s", strerror(errno));
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return -1;
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}
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if (process_response(1, seq) < 0)
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return -1;
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*state = addresses ? STATE_SLEEPING : STATE_START;
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return 0;
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}
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int iface_process(Event *event) {
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int b;
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assert(fd >= 0);
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b = !!addresses;
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if (process_response(0, 0) < 0)
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return -1;
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if (b && !addresses)
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*event = EVENT_ROUTABLE_ADDR_UNCONFIGURED;
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else if (!b && addresses)
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*event = EVENT_ROUTABLE_ADDR_CONFIGURED;
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return 0;
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}
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void iface_done(void) {
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Address *a;
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if (fd >= 0) {
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close(fd);
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fd = -1;
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}
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while ((a = addresses)) {
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AVAHI_LLIST_REMOVE(Address, addresses, addresses, a);
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avahi_free(a);
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}
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}
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