/**
* nfnl_catch - get responses from the nfnetlink system and process them
* @h: nfnetlink handler
*
* This function handles the data received from the nfnetlink system.
* For example, events generated by one of the subsystems. The message
* is passed to the callback registered via callback_register(). Note that
* this a replacement of nfnl_listen and its use is recommended.
*
* On success, 0 is returned. On error, a -1 is returned. If you do not
* want to listen to events anymore, then your callback must return
* NFNL_CB_STOP.
*
* Note that ENOBUFS is returned in case that nfnetlink is exhausted. In
* that case is possible that the information requested is incomplete.
*/
int nfnl_catch(struct nfnl_handle *h)
{
int ret;
assert(h);
while (1) {
unsigned char buf[h->rcv_buffer_size]
__attribute__ ((aligned));
ret = nfnl_recv(h, buf, sizeof(buf));
if (ret == -1) {
/* interrupted syscall must retry */
if (errno == EINTR)
continue;
break;
}
ret = nfnl_process(h, buf, ret);
if (ret <= NFNL_CB_STOP)
break;
}
return ret;
}
/**
* nfnl_catch - get responses from the nfnetlink system and process them
* @h: nfnetlink handler
*
* This function handles the data received from the nfnetlink system.
* For example, events generated by one of the subsystems. The message
* is passed to the callback registered via callback_register(). Note that
* this a replacement of nfnl_listen and its use is recommended.
*
* On success, 0 is returned. On error, a -1 is returned. If you do not
* want to listen to events anymore, then your callback must return
* NFNL_CB_STOP.
*
* Note that ENOBUFS is returned in case that nfnetlink is exhausted. In
* that case is possible that the information requested is incomplete.
*/
int nfnl_catch(struct nfnl_handle *h)
{
int ret;
unsigned int size = NFNL_BUFFSIZE;
assert(h);
/*
* Since nfqueue can send big packets, we don't know how big
* must be the buffer that have to store the received data.
*/
{
unsigned char buf[size];
struct sockaddr_nl peer;
struct iovec iov = {
.iov_len = size,
};
struct msghdr msg = {
.msg_name = (void *) &peer,
.msg_namelen = sizeof(peer),
.msg_iov = &iov,
.msg_iovlen = 1,
.msg_control = NULL,
.msg_controllen = 0,
.msg_flags = 0
};
memset(&peer, 0, sizeof(peer));
peer.nl_family = AF_NETLINK;
iov.iov_base = buf;
iov.iov_len = size;
retry: ret = recvmsg(h->fd, &msg, MSG_PEEK);
if (ret == -1) {
/* interrupted syscall must retry */
if (errno == EINTR)
goto retry;
/* otherwise give up */
return -1;
}
if (msg.msg_flags & MSG_TRUNC)
/* maximum size of data received from netlink */
size = 65535;
}
/* now, receive data from netlink */
while (1) {
unsigned char buf[size];
ret = nfnl_recv(h, buf, sizeof(buf));
if (ret == -1) {
/* interrupted syscall must retry */
if (errno == EINTR)
continue;
break;
}
ret = nfnl_process(h, buf, ret);
if (ret <= NFNL_CB_STOP)
break;
}
return ret;
}
/**
* nfnl_query - request/response communication challenge
* @h: nfnetlink handler
* @nlh: nfnetlink message to be sent
*
* This function sends a nfnetlink message to a certain subsystem and
* receives the response messages associated, such messages are passed to
* the callback registered via register_callback(). Note that this function
* is a replacement for nfnl_talk, its use is recommended.
*
* On success, 0 is returned. On error, a negative is returned. If your
* does not want to listen to events anymore, then your callback must
* return NFNL_CB_STOP.
*
* Note that ENOBUFS is returned in case that nfnetlink is exhausted. In
* that case is possible that the information requested is incomplete.
*/
int nfnl_query(struct nfnl_handle *h, struct nlmsghdr *nlh)
{
assert(h);
assert(nlh);
if (nfnl_send(h, nlh) == -1)
return -1;
return nfnl_catch(h);
}
