c - 格式错误的 DNS 响应

Question

我正在尝试向我的浏览器发送一条 dns 响应消息，现在我创建了一些结构并为 drupal.org 网站填写了一个结构。

当我发送响应时，wiresharks 说它格式错误，有人可以看一下吗？

dnsresponse response;
    unsigned char buf[sizeof response];


    response.id = (unsigned short) htons(GetCurrentProcessId());
    response.response = 1;
    response.opCode = 0;
    response.authoritative = 0;
    response.truncated = 0;
    response.recursion = 1;
    response.recursionAvField = 1;
    response.z = 0;

    response.replyCode = 0;

    response.questions = 1;
    response.answer = 1;
    response.authorityRRS = 0;
    response.additionalRRS = 0;

    response.qName = (unsigned char *)malloc(sizeof("www.drupal.org"));
    response.qType = 1;
    response.qClass = 1;

    response.aName = (unsigned char *)malloc(sizeof("www.drupal.org"));
    response.aType = 1;
    response.aClass = 1;
    response.ttl = 0;
    response.dataLength = 9;
    response.addr = 2362640912;

    memcpy(buf, &response, sizeof response);

我的结构如下:

typedef struct
{
unsigned short id; // ID nummer
unsigned short response :1; // 1 is reply 0 is query
unsigned short opCode :4;
unsigned short authoritative :1; // DNS server is authoritative server
unsigned short truncated :1;
unsigned short recursion :1; // Recursie of niet
unsigned short recursionAvField :1; // Recursie in reply
unsigned short z :3;
//unsigned short aa;
//unsigned short nAD;
unsigned short replyCode :4;

unsigned short questions;
unsigned short answer;
unsigned short authorityRRS;
unsigned short additionalRRS;

unsigned char * qName;
unsigned short qType;
unsigned short qClass;

unsigned char * aName;
unsigned short aType;
unsigned short aClass;
int ttl :32;
unsigned short dataLength;
unsigned int addr :32;
}dnsresponse;

亲切的问候，

Answer 1

我不知道协议(protocol)级别的 dns，但你的问题是

malloc(sizeof("string"))

是否不复制字符串，它只为执行此操作所需的字节保留空间 - 提示:strdup

编辑:哦，我只读了 nos 评论中的“获取 dns 规范”部分。抱歉，重复了。