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/* $Id$ */
/***
This file is part of avahi.
avahi is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation; either version 2.1 of the
License, or (at your option) any later version.
avahi is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with avahi; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
USA.
***/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/ioctl.h>
#include <assert.h>
#include <avahi-common/malloc.h>
#include "netlink.h"
#include "log.h"
struct AvahiNetlink {
int fd;
unsigned seq;
AvahiNetlinkCallback callback;
void* userdata;
uint8_t* buffer;
size_t buffer_length;
const AvahiPoll *poll_api;
AvahiWatch *watch;
};
int avahi_netlink_work(AvahiNetlink *nl, int block) {
ssize_t bytes;
struct msghdr smsg;
struct cmsghdr *cmsg;
struct ucred *cred;
struct iovec iov;
struct nlmsghdr *p;
char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
assert(nl);
iov.iov_base = nl->buffer;
iov.iov_len = nl->buffer_length;
smsg.msg_name = (void*) NULL;
smsg.msg_namelen = 0;
smsg.msg_iov = &iov;
smsg.msg_iovlen = 1;
smsg.msg_control = cred_msg;
smsg.msg_controllen = sizeof(cred_msg);
smsg.msg_flags = (block ? 0 : MSG_DONTWAIT);
if ((bytes = recvmsg(nl->fd, &smsg, 0)) < 0) {
if (errno == EAGAIN || errno == EINTR)
return 0;
avahi_log_error(__FILE__": recvmsg() failed: %s", strerror(errno));
return -1;
}
cmsg = CMSG_FIRSTHDR(&smsg);
cred = (struct ucred *) CMSG_DATA (cmsg);
if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) {
avahi_log_error("No sender credentials received, ignoring data.");
return -1;
}
if (cred->uid != 0) {
avahi_log_warn("Netlink message received from cred->uid != 0 (%d)", cred->uid);
return -1;
}
p = (struct nlmsghdr *) nl->buffer;
assert(nl->callback);
for (; bytes > 0; p = NLMSG_NEXT(p, bytes)) {
if (!NLMSG_OK(p, (size_t) bytes)) {
avahi_log_warn(__FILE__": packet truncated");
return -1;
}
nl->callback(nl, p, nl->userdata);
}
return 0;
}
static void socket_event(AvahiWatch *w, int fd, AVAHI_GCC_UNUSED AvahiWatchEvent event, void *userdata) {
AvahiNetlink *nl = userdata;
assert(w);
assert(nl);
assert(fd == nl->fd);
avahi_netlink_work(nl, 0);
}
AvahiNetlink *avahi_netlink_new(const AvahiPoll *poll_api, uint32_t groups, void (*cb) (AvahiNetlink *nl, struct nlmsghdr *n, void* userdata), void* userdata) {
int fd = -1;
const int on = 1;
struct sockaddr_nl addr;
AvahiNetlink *nl = NULL;
assert(poll_api);
assert(cb);
if ((fd = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE)) < 0) {
avahi_log_error(__FILE__": socket(PF_NETLINK): %s", strerror(errno));
return NULL;
}
memset(&addr, 0, sizeof(addr));
addr.nl_family = AF_NETLINK;
addr.nl_groups = groups;
addr.nl_pid = getpid();
if (bind(fd, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
avahi_log_error(__FILE__": bind(): %s", strerror(errno));
goto fail;
}
if (setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on)) < 0) {
avahi_log_error(__FILE__": bind(): %s", strerror(errno));
goto fail;
}
if (!(nl = avahi_new(AvahiNetlink, 1))) {
avahi_log_error(__FILE__": avahi_new() failed.");
goto fail;
}
nl->poll_api = poll_api;
nl->fd = fd;
nl->seq = 0;
nl->callback = cb;
nl->userdata = userdata;
if (!(nl->buffer = avahi_new(uint8_t, nl->buffer_length = 64*1024))) {
avahi_log_error(__FILE__": avahi_new() failed.");
goto fail;
}
if (!(nl->watch = poll_api->watch_new(poll_api, fd, AVAHI_WATCH_IN, socket_event, nl))) {
avahi_log_error(__FILE__": Failed to create watch.");
goto fail;
}
return nl;
fail:
if (fd >= 0)
close(fd);
if (nl) {
avahi_free(nl->buffer);
avahi_free(nl);
}
return NULL;
}
void avahi_netlink_free(AvahiNetlink *nl) {
assert(nl);
if (nl->watch)
nl->poll_api->watch_free(nl->watch);
if (nl->fd >= 0)
close(nl->fd);
avahi_free(nl->buffer);
avahi_free(nl);
}
int avahi_netlink_send(AvahiNetlink *nl, struct nlmsghdr *m, unsigned *ret_seq) {
assert(nl);
assert(m);
m->nlmsg_seq = nl->seq++;
m->nlmsg_flags |= NLM_F_ACK;
if (send(nl->fd, m, m->nlmsg_len, 0) < 0) {
avahi_log_error(__FILE__": send(): %s", strerror(errno));
return -1;
}
if (ret_seq)
*ret_seq = m->nlmsg_seq;
return 0;
}
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