Linux C++ 发送DHCP报文获取DHCP信息,帮我写一个可执行的cpp文件

好的，以下是一个简单的可执行的C++文件，用于发送DHCP报文获取DHCP信息：

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <net/if.h>
#include <unistd.h>
#include <linux/if_ether.h>
#include <linux/if_packet.h>
#include <linux/ip.h>
#include <linux/udp.h>

using namespace std;

#define BUF_SIZE 1024

struct dhcp_packet {
    uint8_t  op;           /* op: Message opcode/type */
    uint8_t  htype;        /* htype: Hardware addr type */
    uint8_t  hlen;         /* hlen: Hardware addr length */
    uint8_t  hops;         /* hops: Number of relay agent hops from client */
    uint32_t xid;          /* xid: Transaction ID */
    uint16_t secs;         /* secs: Seconds since client started trying to boot */
    uint16_t flags;        /* flags: Flag bits */
    struct in_addr ciaddr; /* ciaddr: Client IP address (if already in use) */
    struct in_addr yiaddr; /* yiaddr: Your (client) IP address */
    struct in_addr siaddr; /* siaddr: Next server to use in bootstrap */
    struct in_addr giaddr; /* giaddr: Relay agent IP address */
    uint8_t  chaddr[16];   /* chaddr: Client hardware address */
    uint8_t  sname[64];    /* sname: Server host name */
    uint8_t  file[128];    /* file: Boot file name */
    uint8_t  options[312]; /* options: Optional parameters (actual length dependent on MTU). */
};

int main() {
    int sock = socket(AF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));
    if (sock < 0) {
        perror("socket");
        exit(1);
    }

    // 获取网络接口列表
    struct if_nameindex *if_nidxs = if_nameindex();
    if (if_nidxs == NULL) {
        perror("if_nameindex");
        exit(1);
    }

    // 打印网络接口列表
    for (struct if_nameindex *p = if_nidxs; p->if_name != NULL; p++) {
        cout << p->if_name << endl;
    }

    // 选择一个网络接口
    int if_index = if_nametoindex("eth0");
    if (if_index == 0) {
        perror("if_nametoindex");
        exit(1);
    }

    // 设置套接字选项
    int on = 1;
    if (setsockopt(sock, IPPROTO_IP, IP_HDRINCL, &on, sizeof(on)) < 0) {
        perror("setsockopt");
        exit(1);
    }

    // 构造DHCP报文
    struct dhcp_packet dhcp_pkt;
    memset(&dhcp_pkt, 0, sizeof(dhcp_pkt));
    dhcp_pkt.op = BOOTREQUEST;
    dhcp_pkt.htype = ARPHRD_ETHER;
    dhcp_pkt.hlen = ETH_ALEN;
    dhcp_pkt.xid = htonl(random());
    memcpy(dhcp_pkt.chaddr, "\x00\x0c\x29\x4c\x28\x9c", ETH_ALEN);

    struct sockaddr_ll addr;
    memset(&addr, 0, sizeof(addr));
    addr.sll_family = AF_PACKET;
    addr.sll_ifindex = if_index;
    addr.sll_halen = ETH_ALEN;
    memcpy(addr.sll_addr, "\xff\xff\xff\xff\xff\xff", ETH_ALEN);

    // 发送DHCP报文
    if (sendto(sock, &dhcp_pkt, sizeof(dhcp_pkt), 0, (struct sockaddr*)&addr, sizeof(addr)) < 0) {
        perror("sendto");
        exit(1);
    }

    // 接收DHCP响应报文
    char buf[BUF_SIZE];
    ssize_t n = recv(sock, buf, BUF_SIZE, 0);
    if (n < 0) {
        perror("recv");
        exit(1);
    }

    // 解析DHCP响应报文
    struct iphdr *iph = (struct iphdr*)buf;
    struct udphdr *udph = (struct udphdr*)(buf + sizeof(struct iphdr));
    struct dhcp_packet *dhcp_pkt_resp = (struct dhcp_packet*)(buf + sizeof(struct iphdr) + sizeof(struct udphdr));
    struct in_addr ip_addr = { dhcp_pkt_resp->yiaddr.s_addr };
    cout << "IP address: " << inet_ntoa(ip_addr) << endl;

    return 0;
}

在运行该程序之前，需要根据实际情况修改以下内容：

1. 选择正确的网络接口：在代码中选择一个网络接口，如"eth0"，需要根据实际情况修改。

2. 填写正确的MAC地址：在构造DHCP报文时，需要填写客户端的MAC地址，需要根据实际情况修改。

运行该程序需要root权限，可以使用以下命令运行：

$ sudo ./dhcp_client

希望对你有所帮助！