dpdk 实现链接跟踪-DPDK中文网

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, &eth_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。