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#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <time.h>
#include <arpa/inet.h>
#include <libmnl/libmnl.h>
#include <libnetfilter_conntrack/libnetfilter_conntrack.h>
static int data_cb(const struct nlmsghdr *nlh, void *data)
{
struct nf_expect *exp;
uint32_t type = NFCT_T_UNKNOWN;
char buf[4096];
exp = nfexp_new();
if (exp == NULL)
return MNL_CB_OK;
if (nfexp_nlmsg_parse(nlh, exp) < 0) {
perror("failed to parse message from kernel");
return MNL_CB_ERROR;
}
nfexp_snprintf(buf, sizeof(buf), exp, type, NFCT_O_DEFAULT, 0);
printf("%s\n", buf);
nfexp_destroy(exp);
return MNL_CB_OK;
}
int main(void)
{
struct mnl_socket *nl;
char buf[MNL_SOCKET_BUFFER_SIZE];
struct nlmsghdr *nlh;
struct nfgenmsg *nfh;
uint32_t seq, portid;
int ret;
nl = mnl_socket_open(NETLINK_NETFILTER);
if (nl == NULL) {
perror("mnl_socket_open");
exit(EXIT_FAILURE);
}
if (mnl_socket_bind(nl, 0, MNL_SOCKET_AUTOPID) < 0) {
perror("mnl_socket_bind");
exit(EXIT_FAILURE);
}
portid = mnl_socket_get_portid(nl);
nlh = mnl_nlmsg_put_header(buf);
nlh->nlmsg_type = (NFNL_SUBSYS_CTNETLINK_EXP << 8) | IPCTNL_MSG_EXP_GET;
nlh->nlmsg_flags = NLM_F_REQUEST|NLM_F_DUMP|NLM_F_ACK;
nlh->nlmsg_seq = seq = time(NULL);
nfh = mnl_nlmsg_put_extra_header(nlh, sizeof(struct nfgenmsg));
nfh->nfgen_family = AF_INET;
nfh->version = NFNETLINK_V0;
nfh->res_id = 0;
ret = mnl_socket_sendto(nl, nlh, nlh->nlmsg_len);
if (ret == -1) {
perror("mnl_socket_recvfrom");
exit(EXIT_FAILURE);
}
ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
while (1) {
ret = mnl_cb_run(buf, ret, seq, portid, data_cb, NULL);
if (ret <= MNL_CB_STOP)
break;
ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
}
if (ret == -1) {
perror("mnl_socket_recvfrom");
exit(EXIT_FAILURE);
}
mnl_socket_close(nl);
return 0;
}
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