经过TCP/IP协议栈发送802.1Q报文

要经过TCP/IP协议栈发送802.1Q报文，需要在数据包中添加802.1Q VLAN标签，并将其发送到网络接口。以下是一个简单的示例程序，演示如何使用TCP/IP协议栈发送带有802.1Q VLAN标签的数据包：

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <arpa/inet.h>
#include <net/ethernet.h>
#include <net/if.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/tcp.h>
#include <netinet/udp.h>
#include <netinet/ip_icmp.h>
#include <linux/if_packet.h>
#include <linux/if_ether.h>
#include <linux/if_vlan.h>

int main()
{
    int sock = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL));

    if (sock < 0) {
        perror("socket");
        exit(1);
    }

    char ifname[IFNAMSIZ] = "eth0";
    struct ifreq ifr;
    strncpy(ifr.ifr_name, ifname, IFNAMSIZ - 1);
    if (ioctl(sock, SIOCGIFINDEX, &ifr) < 0) {
        perror("ioctl");
        exit(1);
    }

    struct sockaddr_ll addr;
    memset(&addr, 0, sizeof(addr));
    addr.sll_family = AF_PACKET;
    addr.sll_ifindex = ifr.ifr_ifindex;

    // 构造802.1Q VLAN标签
    struct vlan_tag {
        uint16_t tci;
        uint16_t ether_type;
    } __attribute__((packed));

    struct vlan_tag vlan;
    vlan.tci = htons(0x100);
    vlan.ether_type = htons(ETH_P_IP);

    // 构造IP数据包
    char ip_packet[ETH_FRAME_LEN];
    struct iphdr *iph = (struct iphdr *)ip_packet;
    iph->version = 4;
    iph->ihl = 5;
    iph->tos = 0;
    iph->tot_len = htons(sizeof(struct iphdr) + sizeof(struct udphdr));
    iph->id = htons(0);
    iph->frag_off = htons(0);
    iph->ttl = 64;
    iph->protocol = IPPROTO_UDP;
    iph->check = htons(0);
    iph->saddr = inet_addr("192.168.1.100");
    iph->daddr = inet_addr("192.168.1.1");

    // 构造UDP数据包
    char udp_packet[ETH_FRAME_LEN];
    struct udphdr *udph = (struct udphdr *)udp_packet;
    udph->source = htons(1234);
    udph->dest = htons(5678);
    udph->len = htons(sizeof(struct udphdr));
    udph->check = htons(0);

    // 将IP头和UDP数据拷贝到数据包中
    memcpy(ip_packet + sizeof(struct iphdr), udph, sizeof(struct udphdr));

    // 将802.1Q VLAN标签和IP/UDP数据拷贝到数据包中
    char packet[ETH_FRAME_LEN];
    memcpy(packet, "\xff\xff\xff\xff\xff\xff", ETH_ALEN);
    memcpy(packet + ETH_ALEN, "\x00\x11\x22\x33\x44\x55", ETH_ALEN);
    memcpy(packet + 2 * ETH_ALEN, &vlan, sizeof(struct vlan_tag));
    memcpy(packet + 2 * ETH_ALEN + sizeof(struct vlan_tag), ip_packet, sizeof(struct iphdr) + sizeof(struct udphdr));

    // 发送数据包
    if (sendto(sock, packet, 2 * ETH_ALEN + sizeof(struct vlan_tag) + sizeof(struct iphdr) + sizeof(struct udphdr), 0, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
        perror("sendto");
        exit(1);
    }

    close(sock);
    return 0;
}

该程序使用socket API创建了一个PF_PACKET类型的socket，并将其绑定到网络接口上。然后，程序构造了一个带有802.1Q VLAN标签的IP/UDP数据包，并将其封装成一个以太网帧。在构造802.1Q VLAN标签时，程序使用了vlan_tag结构体来定义标签格式，并将其添加到数据包的头部。最后，程序调用sendto函数将数据包发送到目标MAC地址。