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我在解析DNS響應時遇到了一些麻煩。以下是我的代碼。以下是結構。我在printf()中遇到了分段錯誤,我嘗試打印QNAME。解析DNS響應
我是非常業餘的,當談到C編程,所以即時通訊不確定哪裏會出錯。任何幫助/提示或鏈接到有用的資源/教程,將不勝感激。函數verfify_header()可以正常工作。我不確定HEADER爲什麼使用memcpy()正確提取。而其他領域則沒有。
struct HEADER{
unsigned short ID;
unsigned char RD:1;
unsigned char TC:1;
unsigned char AA:1;
unsigned char Opcode:4;
unsigned char QR:1;
unsigned char RCODE:4;
unsigned char Z:3;
unsigned char RA:1;
unsigned short QDCOUNT;
unsigned short ANCOUNT;
unsigned short NSCOUNT;
unsigned short ARCOUNT;
};
struct REQ_DATA{
unsigned short qtype;
unsigned short qclass;
};
struct QUESTION{
char* qname;
struct REQ_DATA field;
};
struct RES_DATA{
unsigned short type;
unsigned short class;
unsigned int ttl;
unsigned short rdlength;
};
struct RESPONSE{
char* name;
struct RES_DATA field;
char* rdata;
};
以下是解析dns響應的函數。
void parse_response(char *recvbuf, struct result *res)
{
struct HEADER *rechd = (struct HEADER*) malloc(sizeof(struct HEADER));
struct QUESTION qst;
struct RESPONSE *rp = (struct RESPONSE*) malloc(sizeof(struct RESPONSE));
struct RES_DATA fld;
char* rname = (char*)malloc(sizeof(char));
int hlen,qlen,rlen;
hlen = sizeof(struct HEADER);
memcpy(rechd,recvbuf,hlen);
verify_header(rechd); //This function works correctly
qlen = sizeof(struct QUESTION);
//RESPONSE is after QUESTION and HEADER
rlen = sizeof(struct RESPONSE);
int length = hlen + qlen;
rp = (struct RESPONSE*)(recvbuf + length);
//memcpy(rp, recbbuf + length, sizeof(struct RESPONSE));
memcpy(rname, rp, strlen(rname) + 1);
printf("QNAME: %s\n", *rname); //Segmentation Fault occurs over here!!!!!
}
感謝, 錢德爾
你不需要* on * rname – 2010-11-19 21:44:53
我得到一個NULL值。此外,我試圖使用memmove()無論使用memcpy,但仍然是相同的結果 – 2010-11-19 21:54:04