DPDK是一个高性能的数据包处理框架,它提供了一组API和工具来实现数据包的接收、发送、过滤、转发等功能。对于连接跟踪,可以使用DPDK提供的API实现基于四元组(源IP、目标IP、源端口、目标端口)的匹配和状态维护。
下面是一个简单的示例,演示如何使用DPDK实现连接跟踪:
#include <stdio.h>
#include <stdint.h>
#include <unistd.h>
#include <rte_eal.h>
#include <rte_ethdev.h>
#include <rte_mbuf.h>
#include <rte_ip.h>
#include <rte_tcp.h>
#include <rte_udp.h>
#define RX_RING_SIZE 128
#define TX_RING_SIZE 512
static const struct rte_eth_conf port_conf_default = {
.rxmode = { .max_rx_pkt_len = ETHER_MAX_LEN }
};
static uint16_t nb_rxd = RX_RING_SIZE;
static uint16_t nb_txd = TX_RING_SIZE;
static struct rte_eth_dev_info dev_info;
static struct rte_ether_addr eth_addr;
struct conn_track_table_entry {
uint32_t src_ip;
uint32_t dst_ip;
uint16_t src_port;
uint16_t dst_port;
uint8_t proto;
uint8_t state;
};
#define CONN_TRACK_TABLE_SIZE 1024
static struct conn_track_table_entry conn_track_table[CONN_TRACK_TABLE_SIZE];
static uint32_t
hash_func(uint32_t src_ip, uint32_t dst_ip, uint16_t src_port, uint16_t dst_port, uint8_t proto)
{
uint32_t hash = (src_ip ^ dst_ip) + src_port + dst_port + proto;
return hash % CONN_TRACK_TABLE_SIZE;
}
static void
conn_track_table_init(void)
{
memset(&conn_track_table, 0, sizeof(conn_track_table));
}
static void
conn_track_table_add(uint32_t src_ip, uint32_t dst_ip, uint16_t src_port, uint16_t dst_port, uint8_t proto)
{
uint32_t hash = hash_func(src_ip, dst_ip, src_port, dst_port, proto);
struct conn_track_table_entry *entry = &conn_track_table[hash];
entry->src_ip = src_ip;
entry->dst_ip = dst_ip;
entry->src_port = src_port;
entry->dst_port = dst_port;
entry->proto = proto;
entry->state = 1; // new connection
}
static int
conn_track_table_find(uint32_t src_ip, uint32_t dst_ip, uint16_t src_port, uint16_t dst_port, uint8_t proto)
{
uint32_t hash = hash_func(src_ip, dst_ip, src_port, dst_port, proto);
struct conn_track_table_entry *entry = &conn_track_table[hash];
if (entry->src_ip == src_ip && entry->dst_ip == dst_ip &&
entry->src_port == src_port && entry->dst_port == dst_port &&
entry->proto == proto) {
return entry->state;
}
return -1;
}
static void
conn_track_table_update(uint32_t src_ip, uint32_t dst_ip, uint16_t src_port, uint16_t dst_port, uint8_t proto, uint8_t state)
{
uint32_t hash = hash_func(src_ip, dst_ip, src_port, dst_port, proto);
struct conn_track_table_entry *entry = &conn_track_table[hash];
if (entry->src_ip == src_ip && entry->dst_ip == dst_ip &&
entry->src_port == src_port && entry->dst_port == dst_port &&
entry->proto == proto) {
entry->state = state;
}
}
static void
dpdk_init(int argc, char **argv)
{
int ret;
ret = rte_eal_init(argc, argv);
if (ret < 0)
rte_exit(EXIT_FAILURE, "Cannot init EAL\n");
argc -= ret;
argv += ret;
ret = rte_eth_dev_count_avail();
if (ret < 1)
rte_exit(EXIT_FAILURE, "No Ethernet ports available\n");
ret = rte_eth_dev_get_info_by_index(0, &dev_info);
if (ret != 0)
rte_exit(EXIT_FAILURE, "Cannot get device info\n");
rte_eth_macaddr_get(0, ð_addr);
ret = rte_eth_dev_configure(0, 1, 1, &port_conf_default);
if (ret < 0)
rte_exit(EXIT_FAILURE, "Cannot configure device\n");
ret = rte_eth_rx_queue_setup(0, 0, nb_rxd,
rte_eth_dev_socket_id(0),
NULL,
rte_pktmbuf_pool_create("RX_POOL", /* ... */));
if (ret < 0)
rte_exit(EXIT_FAILURE, "Cannot setup RX queue\n");
ret = rte_eth_tx_queue_setup(0, 0, nb_txd,
rte_eth_dev_socket_id(0),
NULL);
if (ret < 0)
rte_exit(EXIT_FAILURE, "Cannot setup TX queue\n");
ret = rte_eth_dev_start(0);
if (ret < 0)
rte_exit(EXIT_FAILURE, "Cannot start device\n");
}
static void
dpdk_main_loop(void)
{
struct rte_mbuf *pkts_burst[32];
uint16_t nb_rx;
for (;;) {
nb_rx = rte_eth_rx_burst(0, 0, pkts_burst, 32);
if (nb_rx == 0)
continue;
for (int i = 0; i < nb_rx; i++) {
struct rte_mbuf *pkt = pkts_burst[i];
struct rte_ether_hdr *eth_hdr = rte_pktmbuf_mtod(pkt, struct rte_ether_hdr *);
if (eth_hdr->ether_type != rte_cpu_to_be_16(RTE_ETHER_TYPE_IPv4))
continue;
struct rte_ipv4_hdr *ip_hdr = (struct rte_ipv4_hdr *)(eth_hdr + 1);
if (ip_hdr->next_proto_id == IPPROTO_TCP) {
struct rte_tcp_hdr *tcp_hdr = (struct rte_tcp_hdr *)((char *)ip_hdr + ip_hdr->version_ihl*4);
uint32_t src_ip = ip_hdr->src_addr;
uint32_t dst_ip = ip_hdr->dst_addr;
uint16_t src_port = tcp_hdr->src_port;
uint16_t dst_port = tcp_hdr->dst_port;
uint8_t proto = IPPROTO_TCP;
int state = conn_track_table_find(src_ip, dst_ip, src_port, dst_port, proto);
if (state == -1) {
conn_track_table_add(src_ip, dst_ip, src_port, dst_port, proto);
state = 1; // new connection
}
else {
conn_track_table_update(src_ip, dst_ip, src_port, dst_port, proto, state+1);
}
// do something with the packet according to the connection state
// ...
}
else if (ip_hdr->next_proto_id == IPPROTO_UDP) {
struct rte_udp_hdr *udp_hdr = (struct rte_udp_hdr *)((char *)ip_hdr + ip_hdr->version_ihl*4);
uint32_t src_ip = ip_hdr->src_addr;
uint32_t dst_ip = ip_hdr->dst_addr;
uint16_t src_port = udp_hdr->src_port;
uint16_t dst_port = udp_hdr->dst_port;
uint8_t proto = IPPROTO_UDP;
int state = conn_track_table_find(src_ip, dst_ip, src_port, dst_port, proto);
if (state == -1) {
conn_track_table_add(src_ip, dst_ip, src_port, dst_port, proto);
state = 1; // new connection
}
else {
conn_track_table_update(src_ip, dst_ip, src_port, dst_port, proto, state+1);
}
// do something with the packet according to the connection state
// ...
}
rte_pktmbuf_free(pkt);
}
}
}
int main(int argc, char **argv)
{
dpdk_init(argc, argv);
conn_track_table_init();
dpdk_main_loop();
return 0;
}
在上面的示例中,我们使用了一个简单的哈希表来维护连接跟踪状态。每个连接跟踪对象包含了源IP、目标IP、源端口、目标端口和协议类型。当有新的数据包到来时,我们根据四元组信息查找相应的连接跟踪对象。如果没有找到,则添加一个新的对象;如果已经存在一个对象,则更新其状态。最后根据连接状态来处理数据包。