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/* This example is placed in the public domain. */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <time.h>
#include <sys/select.h>
#include <string.h>
#include <libmnl/libmnl.h>
#include <linux/netfilter/nfnetlink.h>
#include <linux/netfilter/nfnetlink_conntrack.h>
#include <linux/netfilter/nf_conntrack_common.h>
#include <linux/netfilter/nf_conntrack_tcp.h>
static void put_msg(char *buf, uint16_t i, int seq)
{
struct nlmsghdr *nlh;
struct nfgenmsg *nfh;
struct nlattr *nest1, *nest2;
nlh = mnl_nlmsg_put_header(buf);
nlh->nlmsg_type = (NFNL_SUBSYS_CTNETLINK << 8) | IPCTNL_MSG_CT_NEW;
nlh->nlmsg_flags = NLM_F_REQUEST|NLM_F_CREATE|NLM_F_EXCL|NLM_F_ACK;
nlh->nlmsg_seq = seq;
nfh = mnl_nlmsg_put_extra_header(nlh, sizeof(struct nfgenmsg));
nfh->nfgen_family = AF_INET;
nfh->version = NFNETLINK_V0;
nfh->res_id = 0;
nest1 = mnl_attr_nest_start(nlh, CTA_TUPLE_ORIG);
nest2 = mnl_attr_nest_start(nlh, CTA_TUPLE_IP);
mnl_attr_put_u32(nlh, CTA_IP_V4_SRC, inet_addr("1.1.1.1"));
mnl_attr_put_u32(nlh, CTA_IP_V4_DST, inet_addr("2.2.2.2"));
mnl_attr_nest_end(nlh, nest2);
nest2 = mnl_attr_nest_start(nlh, CTA_TUPLE_PROTO);
mnl_attr_put_u8(nlh, CTA_PROTO_NUM, IPPROTO_TCP);
mnl_attr_put_u16(nlh, CTA_PROTO_SRC_PORT, htons(i));
mnl_attr_put_u16(nlh, CTA_PROTO_DST_PORT, htons(1025));
mnl_attr_nest_end(nlh, nest2);
mnl_attr_nest_end(nlh, nest1);
nest1 = mnl_attr_nest_start(nlh, CTA_TUPLE_REPLY);
nest2 = mnl_attr_nest_start(nlh, CTA_TUPLE_IP);
mnl_attr_put_u32(nlh, CTA_IP_V4_SRC, inet_addr("2.2.2.2"));
mnl_attr_put_u32(nlh, CTA_IP_V4_DST, inet_addr("1.1.1.1"));
mnl_attr_nest_end(nlh, nest2);
nest2 = mnl_attr_nest_start(nlh, CTA_TUPLE_PROTO);
mnl_attr_put_u8(nlh, CTA_PROTO_NUM, IPPROTO_TCP);
mnl_attr_put_u16(nlh, CTA_PROTO_SRC_PORT, htons(1025));
mnl_attr_put_u16(nlh, CTA_PROTO_DST_PORT, htons(i));
mnl_attr_nest_end(nlh, nest2);
mnl_attr_nest_end(nlh, nest1);
nest1 = mnl_attr_nest_start(nlh, CTA_PROTOINFO);
nest2 = mnl_attr_nest_start(nlh, CTA_PROTOINFO_TCP);
mnl_attr_put_u8(nlh, CTA_PROTOINFO_TCP_STATE, TCP_CONNTRACK_SYN_SENT);
mnl_attr_nest_end(nlh, nest2);
mnl_attr_nest_end(nlh, nest1);
mnl_attr_put_u32(nlh, CTA_STATUS, htonl(IPS_CONFIRMED));
mnl_attr_put_u32(nlh, CTA_TIMEOUT, htonl(1000));
}
static int cb_err(const struct nlmsghdr *nlh, void *data)
{
struct nlmsgerr *err = mnl_nlmsg_get_payload(nlh);
if (err->error != 0)
printf("message with seq %u has failed: %s\n",
nlh->nlmsg_seq, strerror(-err->error));
return MNL_CB_OK;
}
static mnl_cb_t cb_ctl_array[NLMSG_MIN_TYPE] = {
[NLMSG_ERROR] = cb_err,
};
static void
send_batch(struct mnl_socket *nl, struct mnl_nlmsg_batch *b, int portid)
{
int ret, fd = mnl_socket_get_fd(nl);
size_t len = mnl_nlmsg_batch_size(b);
char rcv_buf[MNL_SOCKET_BUFFER_SIZE];
ret = mnl_socket_sendto(nl, mnl_nlmsg_batch_head(b), len);
if (ret == -1) {
perror("mnl_socket_sendto");
exit(EXIT_FAILURE);
}
/* receive and digest all the acknowledgments from the kernel. */
struct timeval tv = {
.tv_sec = 0,
.tv_usec = 0
};
fd_set readfds;
FD_ZERO(&readfds);
FD_SET(fd, &readfds);
ret = select(fd+1, &readfds, NULL, NULL, &tv);
if (ret == -1) {
perror("select");
exit(EXIT_FAILURE);
}
while (ret > 0 && FD_ISSET(fd, &readfds)) {
ret = mnl_socket_recvfrom(nl, rcv_buf, sizeof(rcv_buf));
if (ret == -1) {
perror("mnl_socket_recvfrom");
exit(EXIT_FAILURE);
}
ret = mnl_cb_run2(rcv_buf, ret, 0, portid,
NULL, NULL, cb_ctl_array,
MNL_ARRAY_SIZE(cb_ctl_array));
if (ret == -1) {
perror("mnl_cb_run2");
exit(EXIT_FAILURE);
}
ret = select(fd+1, &readfds, NULL, NULL, &tv);
if (ret == -1) {
perror("select");
exit(EXIT_FAILURE);
}
FD_ZERO(&readfds);
FD_SET(fd, &readfds);
}
}
int main(void)
{
struct mnl_socket *nl;
char snd_buf[MNL_SOCKET_BUFFER_SIZE*2];
struct mnl_nlmsg_batch *b;
int j;
unsigned int seq, portid;
uint16_t i;
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);
/* The buffer that we use to batch messages is MNL_SOCKET_BUFFER_SIZE
* multiplied by 2 bytes long, but we limit the batch to half of it
* since the last message that does not fit the batch goes over the
* upper boundary, if you break this rule, expect memory corruptions. */
b = mnl_nlmsg_batch_start(snd_buf, MNL_SOCKET_BUFFER_SIZE);
if (b == NULL) {
perror("mnl_nlmsg_batch_start");
exit(EXIT_FAILURE);
}
seq = time(NULL);
for (i=1024, j=0; i<65535; i++, j++) {
put_msg(mnl_nlmsg_batch_current(b), i, seq+j);
/* is there room for more messages in this batch?
* if so, continue. */
if (mnl_nlmsg_batch_next(b))
continue;
send_batch(nl, b, portid);
/* this moves the last message that did not fit into the
* batch to the head of it. */
mnl_nlmsg_batch_reset(b);
}
/* check if there is any message in the batch not sent yet. */
if (!mnl_nlmsg_batch_is_empty(b))
send_batch(nl, b, portid);
mnl_nlmsg_batch_stop(b);
mnl_socket_close(nl);
return 0;
}
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