使用socke技术编写一段代码，使用c++代码，使用socket技术完成获取本地主机的IP地址、子网掩码、网络关地址、域名服务器地址等信息的功能

下面是一个使用C++编写的获取本地主机信息的示例代码：

#include <iostream>
#include <string.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <ifaddrs.h>
#include <netdb.h>
#include <unistd.h>

using namespace std;

// 获取本地主机名和IP地址
void get_host_ip(char* ip) {
    int fd;
    struct ifaddrs *ifa, *ifa_tmp;
    struct sockaddr_in *sin;
    char buf[INET_ADDRSTRLEN];

    if (getifaddrs(&ifa) == -1) {
        perror("getifaddrs");
        return;
    }

    for (ifa_tmp = ifa; ifa_tmp != NULL; ifa_tmp = ifa_tmp->ifa_next) {
        if (ifa_tmp->ifa_addr == NULL) {
            continue;
        }
        if ((ifa_tmp->ifa_flags & IFF_UP) == 0) {
            continue;
        }
        if (ifa_tmp->ifa_addr->sa_family != AF_INET) {
            continue;
        }

        sin = (struct sockaddr_in *)ifa_tmp->ifa_addr;
        inet_ntop(AF_INET, &(sin->sin_addr), buf, INET_ADDRSTRLEN);

        if (strcmp(ifa_tmp->ifa_name, "lo") != 0) {
            strcpy(ip, buf);
            break;
        }
    }

    freeifaddrs(ifa);
}

// 获取本地主机的子网掩码
void get_netmask(char* netmask) {
    int fd;
    struct ifreq ifr;

    fd = socket(AF_INET, SOCK_DGRAM, 0);
    if (fd < 0) {
        perror("socket");
        return;
    }

    strcpy(ifr.ifr_name, "eth0");
    if (ioctl(fd, SIOCGIFNETMASK, &ifr) == -1) {
        perror("ioctl");
        close(fd);
        return;
    }

    inet_ntop(AF_INET, &(reinterpret_cast<struct sockaddr_in*>(&ifr.ifr_addr)->sin_addr), netmask, INET_ADDRSTRLEN);

    close(fd);
}

// 获取本地主机的网关地址
void get_gateway(char* gateway) {
    FILE *fp;
    char buf[256];
    char *iface, *dest, *gw;

    fp = fopen("/proc/net/route", "r");
    if (fp == NULL) {
        perror("fopen");
        return;
    }

    while (fgets(buf, sizeof(buf), fp)) {
        iface = strtok(buf, " \t");
        dest = strtok(NULL, " \t");
        gw = strtok(NULL, " \t");

        if (iface != NULL && dest != NULL && strcmp(dest, "00000000") == 0 && gw != NULL) {
            unsigned long addr = strtoul(gw, NULL, 16);
            struct in_addr inaddr;
            inaddr.s_addr = htonl(addr);
            strcpy(gateway, inet_ntoa(inaddr));
            break;
        }
    }

    fclose(fp);
}

// 获取本地主机的DNS服务器地址
void get_nameservers(char* nameservers) {
    FILE *fp;
    char buf[256];
    char *p;

    fp = fopen("/etc/resolv.conf", "r");
    if (fp == NULL) {
        perror("fopen");
        return;
    }

    while (fgets(buf, sizeof(buf), fp)) {
        if (strncmp(buf, "nameserver", strlen("nameserver")) == 0) {
            p = strtok(buf, " \t\n");
            if (p != NULL) {
                p = strtok(NULL, " \t\n");
                if (p != NULL) {
                    strcat(nameservers, p);
                    strcat(nameservers, " ");
                }
            }
        }
    }

    fclose(fp);
}

int main() {
    char hostname[256];
    char ip_address[INET_ADDRSTRLEN];
    char netmask[INET_ADDRSTRLEN];
    char gateway[INET_ADDRSTRLEN];
    char nameservers[256] = "";

    gethostname(hostname, sizeof(hostname));
    get_host_ip(ip_address);
    get_netmask(netmask);
    get_gateway(gateway);
    get_nameservers(nameservers);

    cout << "Hostname: " << hostname << endl;
    cout << "IP Address: " << ip_address << endl;
    cout << "Netmask: " << netmask << endl;
    cout << "Gateway: " << gateway << endl;
    cout << "Nameservers: " << nameservers << endl;

    return 0;
}

需要注意的是，本代码中获取子网掩码和网关地址的方式是基于Linux系统的，如果您是在其他操作系统上运行此代码，可能需要根据不同的系统做出相应的修改。