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@MeeepMuup
Die DnsQuery-Funktion hab ich schon ausprobiert. Die meldet öfters mal, das eine IP oder ein Name nicht aufgelöst werden kann, obwohl die IP oder der Name ohne Probleme aufgelöst werden kann.
Deshalb will ich ja was mit Sockets machen. Hab jetzt mittlerweile was gefunden, aber damit bekomm ich es nur hin, dass ich den Full Qualified Namen übergebe und die entsprechende IP erhalte.
Was muss ich ändern, damit ich auch IP Adressen übergeben kann und diese in Full Qulaified Names aufgelöst bekomme?
void ngethostbyname(char* dnsServerIP, unsigned char *host)
{
SOCKET s;
s=socket(AF_INET,SOCK_DGRAM,IPPROTO_UDP); //UDP packet for DNS queries
RES_RECORD answers[20],auth[20],addit[20]; //the replies from the DNS server
sockaddr_in dest;
dest.sin_family=AF_INET;
dest.sin_port=htons(53);
dest.sin_addr.s_addr=inet_addr(dnsServerIP); //dns servers
unsigned char buf[65536],*qname,*reader;
DNS_HEADER *dns = NULL;
QUESTION *qinfo = NULL;
//Set the DNS structure to standard queries
dns=(DNS_HEADER*)&buf;
dns->id = (unsigned short)htons(GetCurrentProcessId());
dns->qr = 0; //This is a query
dns->opcode = 0; //This is a standard query
dns->aa = 0; //Not Authoritative
dns->tc = 0; //This message is not truncated
dns->rd = 1; //Recursion Desired
dns->ra = 0; //Recursion not available! hey we dont have it (lol)
dns->z = 0;
dns->ad = 0;
dns->cd = 0;
dns->rcode = 0;
dns->q_count = htons(1); //we have only 1 question
dns->ans_count = 0;
dns->auth_count = 0;
dns->add_count = 0;
//point to the query portion
qname =(unsigned char*)&buf[sizeof(DNS_HEADER)];
ChangetoDnsNameFormat(qname,host);
qinfo =(QUESTION*)&buf[sizeof(DNS_HEADER) + (strlen((const char*)qname) + 1)]; //fill it
qinfo->qtype = htons(1); //we are requesting the ipv4 address
qinfo->qclass = htons(1); //its internet (lol)
printf("\nSending Packet...");
if(sendto(s,(char*)buf,sizeof(DNS_HEADER) + (strlen((const char*)qname)+1) + sizeof(QUESTION),0,(sockaddr*)&dest,sizeof(dest))==SOCKET_ERROR)
{
printf("%d error",WSAGetLastError());
}
printf("Sent");
int i=sizeof(dest);
printf("\nReceiving answer...");
if(recvfrom (s,(char*)buf,65536,0,(sockaddr*)&dest,&i)==SOCKET_ERROR)
{
printf("Failed. Error Code : %d",WSAGetLastError());
}
printf("Received.");
dns=(DNS_HEADER*)buf;
//move ahead of the dns header and the query field
reader=&buf[sizeof(DNS_HEADER) + (strlen((const char*)qname)+1) + sizeof(QUESTION)];
printf("\nThe response contains : ");
printf("\n %d Questions.",ntohs(dns->q_count));
printf("\n %d Answers.",ntohs(dns->ans_count));
printf("\n %d Authoritative Servers.",ntohs(dns->auth_count));
printf("\n %d Additional records.\n\n",ntohs(dns->add_count));
//reading answers
int stop=0;
for(i=0;i<ntohs(dns->ans_count);i++)
{
answers[i].name=ReadName(reader,buf,stop);
reader+=stop;
answers[i].resource=(R_DATA*)(reader);
reader+=sizeof(R_DATA);
if(ntohs(answers[i].resource->type)==1)
{
answers[i].rdata=new unsigned char[ntohs(answers[i].resource->data_len)];
for(int j=0;j<ntohs(answers[i].resource->data_len);j++)
answers[i].rdata[j]=reader[j];
answers[i].rdata[ntohs(answers[i].resource->data_len)]='\0';
reader+=ntohs(answers[i].resource->data_len);
}
else
{
answers[i].rdata=ReadName(reader,buf,stop);
reader+=stop;
}
}
//read authorities
for(i=0;i<ntohs(dns->auth_count);i++)
{
auth[i].name=ReadName(reader,buf,stop);
reader+=stop;
auth[i].resource=(R_DATA*)(reader);
reader+=sizeof(R_DATA);
auth[i].rdata=ReadName(reader,buf,stop);
reader+=stop;
}
//read additional
for(i=0;i<ntohs(dns->add_count);i++)
{
addit[i].name=ReadName(reader,buf,stop);
reader+=stop;
addit[i].resource=(R_DATA*)(reader);
reader+=sizeof(R_DATA);
if(ntohs(addit[i].resource->type)==1)
{
addit[i].rdata=new unsigned char[ntohs(addit[i].resource->data_len)];
for(int j=0;j<ntohs(addit[i].resource->data_len);j++)
addit[i].rdata[j]=reader[j];
addit[i].rdata[ntohs(addit[i].resource->data_len)]='\0';
reader+=ntohs(addit[i].resource->data_len);
}
else
{
addit[i].rdata=ReadName(reader,buf,stop);
reader+=stop;
}
}
//print answers
for(i=0;i<ntohs(dns->ans_count);i++)
{
//printf("\nAnswer : %d",i+1);
printf("Name : %s ",answers[i].name);
if(ntohs(answers[i].resource->type)==1)
{
sockaddr_in a;
long *p;
p=(long*)answers[i].rdata;
a.sin_addr.s_addr=(*p); //working without ntohl
printf("has IPv4 address : %s",inet_ntoa(a.sin_addr));
}
if(ntohs(answers[i].resource->type)==5)
printf("has alias name : %s",answers[i].rdata);
printf("\n");
}
//print authorities
for(i=0;i<ntohs(dns->auth_count);i++)
{
//printf("\nAuthorities : %d",i+1);
printf("Name : %s ",auth[i].name);
if(ntohs(auth[i].resource->type)==2)
printf("has authoritative nameserver : %s",auth[i].rdata);
printf("\n");
}
//print additional resource records
for(i=0;i<ntohs(dns->add_count);i++)
{
//printf("\nAdditional : %d",i+1);
printf("Name : %s ",addit[i].name);
if(ntohs(addit[i].resource->type)==1)
{
sockaddr_in a;
long *p;
p=(long*)addit[i].rdata;
a.sin_addr.s_addr=(*p); //working without ntohl
printf("has IPv4 address : %s",inet_ntoa(a.sin_addr));
}
printf("\n");
}
return;
}
unsigned char* ReadName(unsigned char* reader,unsigned char* buffer,int &count)
{
unsigned char *name;
name=new unsigned char[256];
name[0]='\0';
unsigned int p=0,jumped=0,offset;
count=1;
//read the names in 3www6google3com format
while(*reader!=0)
{
if(*reader>=192)
{
offset = (*reader)*256 + *(reader+1) - 49152; //49152 = 11000000 00000000 ;)
reader = buffer + offset - 1;
jumped = 1; //we have jumped to another location so counting wont go up!
}
else
name[p++]=*reader;
reader=reader+1;
if(jumped==0) count++; //if we havent jumped to another location then we can count up
}
name[p]='\0'; //string complete
if(jumped==1) count++; //number of steps we actually moved forward in the packet
//now convert 3www6google3com0 to www.google.com
for(int i=0;i<(int)strlen((const char*)name);i++)
{
p=name[i];
for(int j=0;j<(int)p;j++)
{
name[i]=name[i+1];
i=i+1;
}
name[i]='.';
}
name[i-1]='\0'; //remove the last dot
return name;
}
//this will convert www.google.com to 3www6google3com ;got it :)
void ChangetoDnsNameFormat(unsigned char* dns,unsigned char* host)
{
int lock=0;
strcat((char*)host,".");
for(int i=0;i<(int)strlen((char*)host);i++)
{
if(host[i]=='.')
{
*dns++=i-lock;
for(;lock<i;lock++)
{
*dns++=host[lock];
}
lock++; //or lock=i+1;
}
}
*dns++='\0';
}
Gruß Danny
