/*  * DNS Query Program on Linux  *  * Author : ismdeep@live.com  *  * */ //Header Files #include<stdio.h> //printf #include<string.h> //strlen #include<stdlib.h> //malloc #include<sys/socket.h> //you know what this is for #include<arpa/inet.h> //inet_addr , inet_ntoa , ntohs etc #include<netinet/in.h> #include<unistd.h> //getpid //List of DNS Servers registered on the system char dns_servers[10][100]; int dns_server_count = 0; //Types of DNS resource records :) #define T_A 1 //Ipv4 address #define T_NS 2 //Nameserver #define T_CNAME 5 // canonical name #define T_SOA 6 /* start of authority zone */ #define T_PTR 12 /* domain name pointer */ #define T_MX 15 //Mail server //Function Prototypes void ngethostbyname (unsigned char* , int); void ChangetoDnsNameFormat (unsigned char*,unsigned char*); unsigned char* ReadName (unsigned char*,unsigned char*,int*); void get_dns_servers(); //DNS header structure struct DNS_HEADER {  unsigned short id; // identification number  unsigned char rd :1; // recursion desired  unsigned char tc :1; // truncated message  unsigned char aa :1; // authoritive answer  unsigned char opcode :4; // purpose of message  unsigned char qr :1; // query/response flag  unsigned char rcode :4; // response code  unsigned char cd :1; // checking disabled  unsigned char ad :1; // authenticated data  unsigned char z :1; // its z! reserved  unsigned char ra :1; // recursion available  unsigned short q_count; // number of question entries  unsigned short ans_count; // number of answer entries  unsigned short auth_count; // number of authority entries  unsigned short add_count; // number of resource entries }; //Constant sized fields of query structure struct QUESTION {  unsigned short qtype;  unsigned short qclass; }; //Constant sized fields of the resource record structure #pragma pack(push, 1) struct R_DATA {  unsigned short type;  unsigned short _class;  unsigned int ttl;  unsigned short data_len; }; #pragma pack(pop) //Pointers to resource record contents struct RES_RECORD {  unsigned char *name;  struct R_DATA *resource;  unsigned char *rdata; }; //Structure of a Query typedef struct {  unsigned char *name;  struct QUESTION *ques; } QUERY; int main( int argc , char *argv[]) {  unsigned char hostname[100];  //Get the DNS servers from the resolv.conf file  get_dns_servers();  //Get the hostname from the terminal  printf("Enter Hostname to Lookup : ");  scanf("%s" , hostname);  //Now get the ip of this hostname , A record  ngethostbyname(hostname , T_A);  return 0; } /*  * Perform a DNS query by sending a packet  * */ void ngethostbyname(unsigned char *host , int query_type) {  unsigned char buf[65536],*qname,*reader;  int i , j , stop , s;  struct sockaddr_in a;  struct RES_RECORD answers[20],auth[20],addit[20]; //the replies from the DNS server  struct sockaddr_in dest;  struct DNS_HEADER *dns = NULL;  struct QUESTION *qinfo = NULL;  printf("Resolving %s" , host);  s = socket(AF_INET , SOCK_DGRAM , IPPROTO_UDP); //UDP packet for DNS queries  dest.sin_family = AF_INET;  dest.sin_port = htons(53);  dest.sin_addr.s_addr = inet_addr(dns_servers[0]); //dns servers  //Set the DNS structure to standard queries  dns = (struct DNS_HEADER *)&buf;  dns->id = (unsigned short) htons(getpid());  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(struct DNS_HEADER)];  ChangetoDnsNameFormat(qname , host);  qinfo =(struct QUESTION*)&buf[sizeof(struct DNS_HEADER) + (strlen((const char*)qname) + 1)]; //fill it  qinfo->qtype = htons( query_type ); //type of the query , A , MX , CNAME , NS etc  qinfo->qclass = htons(1); //its internet (lol)  printf("\nSending Packet...");  if( sendto(s,(char*)buf,sizeof(struct DNS_HEADER) + (strlen((const char*)qname)+1) + sizeof(struct QUESTION),0,(struct sockaddr*)&dest,sizeof(dest)) < 0)  {   perror("sendto failed");  }  printf("Done");  //Receive the answer  i = sizeof dest;  printf("\nReceiving answer...");  if(recvfrom (s,(char*)buf , 65536 , 0 , (struct sockaddr*)&dest , (socklen_t*)&i ) < 0)  {   perror("recvfrom failed");  }  printf("Done");  dns = (struct DNS_HEADER*) buf;  //move ahead of the dns header and the query field  reader = &buf[sizeof(struct DNS_HEADER) + (strlen((const char*)qname)+1) + sizeof(struct 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));  //Start reading answers  stop=0;  for(i=0;i<ntohs(dns->ans_count);i++)  {   answers[i].name=ReadName(reader,buf,&stop);   reader = reader + stop;   answers[i].resource = (struct R_DATA*)(reader);   reader = reader + sizeof(struct R_DATA);   if(ntohs(answers[i].resource->type) == 1) //if its an ipv4 address   {    answers[i].rdata = (unsigned char*)malloc(ntohs(answers[i].resource->data_len));    for(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 = reader + ntohs(answers[i].resource->data_len);   }   else   {    answers[i].rdata = ReadName(reader,buf,&stop);    reader = 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=(struct R_DATA*)(reader);   reader+=sizeof(struct 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=(struct R_DATA*)(reader);   reader+=sizeof(struct R_DATA);   if(ntohs(addit[i].resource->type)==1)   {    addit[i].rdata = (unsigned char*)malloc(ntohs(addit[i].resource->data_len));    for(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  printf("\nAnswer Records : %d \n" , ntohs(dns->ans_count) );  for(i=0 ; i < ntohs(dns->ans_count) ; i++)  {   printf("Name : %s ",answers[i].name);   if( ntohs(answers[i].resource->type) == T_A) //IPv4 address   {    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)   {    //Canonical name for an alias    printf("has alias name : %s",answers[i].rdata);   }   printf("\n");  }  //print authorities  printf("\nAuthoritive Records : %d \n" , ntohs(dns->auth_count) );  for( i=0 ; i < ntohs(dns->auth_count) ; i++)  {   printf("Name : %s ",auth[i].name);   if(ntohs(auth[i].resource->type)==2)   {    printf("has nameserver : %s",auth[i].rdata);   }   printf("\n");  }  //print additional resource records  printf("\nAdditional Records : %d \n" , ntohs(dns->add_count) );  for(i=0; i < ntohs(dns->add_count) ; i++)  {   printf("Name : %s ",addit[i].name);   if(ntohs(addit[i].resource->type)==1)   {    long *p;    p=(long*)addit[i].rdata;    a.sin_addr.s_addr=(*p);    printf("has IPv4 address : %s",inet_ntoa(a.sin_addr));   }   printf("\n");  }  return; } /*  *  * */ u_char* ReadName(unsigned char* reader,unsigned char* buffer,int* count) {  unsigned char *name;  unsigned int p=0,jumped=0,offset;  int i , j;  *count = 1;  name = (unsigned char*)malloc(256);  name[0]='\0';  //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 = *count + 1; //if we havent jumped to another location then we can count up   }  }  name[p]='\0'; //string complete  if(jumped==1)  {   *count = *count + 1; //number of steps we actually moved forward in the packet  }  //now convert 3www6google3com0 to www.google.com  for(i=0;i<(int)strlen((const char*)name);i++)  {   p=name[i];   for(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; } /*  * Get the DNS servers from /etc/resolv.conf file on Linux  * */ void get_dns_servers() {  FILE *fp;  char line[200] , *p;  if((fp = fopen("/etc/resolv.conf" , "r")) == NULL)  {   printf("Failed opening /etc/resolv.conf file \n");  }  while(fgets(line , 200 , fp))  {   if(line[0] == '#')   {    continue;   }   if(strncmp(line , "nameserver" , 10) == 0)   {    p = strtok(line , " ");    p = strtok(NULL , " ");    //p now is the dns ip :)    //????   }  }  strcpy(dns_servers[0] , "208.67.222.222");  strcpy(dns_servers[1] , "208.67.220.220"); } /*  * This will convert www.google.com to 3www6google3com  * got it :)  * */ void ChangetoDnsNameFormat(unsigned char* dns,unsigned char* host) {  int lock = 0 , i;  strcat((char*)host,".");  for(i = 0 ; i < strlen((char*)host) ; i++)  {   if(host[i]=='.')   {    *dns++ = i-lock;    for(;lock<i;lock++)    {     *dns++=host[lock];    }    lock++; //or lock=i+1;   }  }  *dns++='\0'; }

/*  * DNS Query Program on Linux  *  * Author : ismdeep@live.com  *  * */ //Header Files #include<stdio.h> //printf #include<string.h> //strlen #include<stdlib.h> //malloc #include<sys/socket.h> //you know what this is for #include<arpa/inet.h> //inet_addr , inet_ntoa , ntohs etc #include<netinet/in.h> #include<unistd.h> //getpid //List of DNS Servers registered on the system char dns_servers[10][100]; int dns_server_count = 0; //Types of DNS resource records :) #define T_A 1 //Ipv4 address #define T_NS 2 //Nameserver #define T_CNAME 5 // canonical name #define T_SOA 6 /* start of authority zone */ #define T_PTR 12 /* domain name pointer */ #define T_MX 15 //Mail server //Function Prototypes void ngethostbyname (unsigned char* , int); void ChangetoDnsNameFormat (unsigned char*,unsigned char*); unsigned char* ReadName (unsigned char*,unsigned char*,int*); void get_dns_servers(); //DNS header structure struct DNS_HEADER {  unsigned short id; // identification number  unsigned char rd :1; // recursion desired  unsigned char tc :1; // truncated message  unsigned char aa :1; // authoritive answer  unsigned char opcode :4; // purpose of message  unsigned char qr :1; // query/response flag  unsigned char rcode :4; // response code  unsigned char cd :1; // checking disabled  unsigned char ad :1; // authenticated data  unsigned char z :1; // its z! reserved  unsigned char ra :1; // recursion available  unsigned short q_count; // number of question entries  unsigned short ans_count; // number of answer entries  unsigned short auth_count; // number of authority entries  unsigned short add_count; // number of resource entries }; //Constant sized fields of query structure struct QUESTION {  unsigned short qtype;  unsigned short qclass; }; //Constant sized fields of the resource record structure #pragma pack(push, 1) struct R_DATA {  unsigned short type;  unsigned short _class;  unsigned int ttl;  unsigned short data_len; }; #pragma pack(pop) //Pointers to resource record contents struct RES_RECORD {  unsigned char *name;  struct R_DATA *resource;  unsigned char *rdata; }; //Structure of a Query typedef struct {  unsigned char *name;  struct QUESTION *ques; } QUERY; int main( int argc , char *argv[]) {  unsigned char hostname[100];  //Get the DNS servers from the resolv.conf file  get_dns_servers();  //Get the hostname from the terminal  printf("Enter Hostname to Lookup : ");  scanf("%s" , hostname);  //Now get the ip of this hostname , A record  ngethostbyname(hostname , T_A);  return 0; } /*  * Perform a DNS query by sending a packet  * */ void ngethostbyname(unsigned char *host , int query_type) {  unsigned char buf[65536],*qname,*reader;  int i , j , stop , s;  struct sockaddr_in a;  struct RES_RECORD answers[20],auth[20],addit[20]; //the replies from the DNS server  struct sockaddr_in dest;  struct DNS_HEADER *dns = NULL;  struct QUESTION *qinfo = NULL;  printf("Resolving %s" , host);  s = socket(AF_INET , SOCK_DGRAM , IPPROTO_UDP); //UDP packet for DNS queries  dest.sin_family = AF_INET;  dest.sin_port = htons(53);  dest.sin_addr.s_addr = inet_addr(dns_servers[0]); //dns servers  //Set the DNS structure to standard queries  dns = (struct DNS_HEADER *)&buf;  dns->id = (unsigned short) htons(getpid());  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(struct DNS_HEADER)];  ChangetoDnsNameFormat(qname , host);  qinfo =(struct QUESTION*)&buf[sizeof(struct DNS_HEADER) + (strlen((const char*)qname) + 1)]; //fill it  qinfo->qtype = htons( query_type ); //type of the query , A , MX , CNAME , NS etc  qinfo->qclass = htons(1); //its internet (lol)  printf("\nSending Packet...");  if( sendto(s,(char*)buf,sizeof(struct DNS_HEADER) + (strlen((const char*)qname)+1) + sizeof(struct QUESTION),0,(struct sockaddr*)&dest,sizeof(dest)) < 0)  {   perror("sendto failed");  }  printf("Done");  //Receive the answer  i = sizeof dest;  printf("\nReceiving answer...");  if(recvfrom (s,(char*)buf , 65536 , 0 , (struct sockaddr*)&dest , (socklen_t*)&i ) < 0)  {   perror("recvfrom failed");  }  printf("Done");  dns = (struct DNS_HEADER*) buf;  //move ahead of the dns header and the query field  reader = &buf[sizeof(struct DNS_HEADER) + (strlen((const char*)qname)+1) + sizeof(struct 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));  //Start reading answers  stop=0;  for(i=0;i<ntohs(dns->ans_count);i++)  {   answers[i].name=ReadName(reader,buf,&stop);   reader = reader + stop;   answers[i].resource = (struct R_DATA*)(reader);   reader = reader + sizeof(struct R_DATA);   if(ntohs(answers[i].resource->type) == 1) //if its an ipv4 address   {    answers[i].rdata = (unsigned char*)malloc(ntohs(answers[i].resource->data_len));    for(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 = reader + ntohs(answers[i].resource->data_len);   }   else   {    answers[i].rdata = ReadName(reader,buf,&stop);    reader = 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=(struct R_DATA*)(reader);   reader+=sizeof(struct 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=(struct R_DATA*)(reader);   reader+=sizeof(struct R_DATA);   if(ntohs(addit[i].resource->type)==1)   {    addit[i].rdata = (unsigned char*)malloc(ntohs(addit[i].resource->data_len));    for(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  printf("\nAnswer Records : %d \n" , ntohs(dns->ans_count) );  for(i=0 ; i < ntohs(dns->ans_count) ; i++)  {   printf("Name : %s ",answers[i].name);   if( ntohs(answers[i].resource->type) == T_A) //IPv4 address   {    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)   {    //Canonical name for an alias    printf("has alias name : %s",answers[i].rdata);   }   printf("\n");  }  //print authorities  printf("\nAuthoritive Records : %d \n" , ntohs(dns->auth_count) );  for( i=0 ; i < ntohs(dns->auth_count) ; i++)  {   printf("Name : %s ",auth[i].name);   if(ntohs(auth[i].resource->type)==2)   {    printf("has nameserver : %s",auth[i].rdata);   }   printf("\n");  }  //print additional resource records  printf("\nAdditional Records : %d \n" , ntohs(dns->add_count) );  for(i=0; i < ntohs(dns->add_count) ; i++)  {   printf("Name : %s ",addit[i].name);   if(ntohs(addit[i].resource->type)==1)   {    long *p;    p=(long*)addit[i].rdata;    a.sin_addr.s_addr=(*p);    printf("has IPv4 address : %s",inet_ntoa(a.sin_addr));   }   printf("\n");  }  return; } /*  *  * */ u_char* ReadName(unsigned char* reader,unsigned char* buffer,int* count) {  unsigned char *name;  unsigned int p=0,jumped=0,offset;  int i , j;  *count = 1;  name = (unsigned char*)malloc(256);  name[0]='\0';  //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 = *count + 1; //if we havent jumped to another location then we can count up   }  }  name[p]='\0'; //string complete  if(jumped==1)  {   *count = *count + 1; //number of steps we actually moved forward in the packet  }  //now convert 3www6google3com0 to www.google.com  for(i=0;i<(int)strlen((const char*)name);i++)  {   p=name[i];   for(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; } /*  * Get the DNS servers from /etc/resolv.conf file on Linux  * */ void get_dns_servers() {  FILE *fp;  char line[200] , *p;  if((fp = fopen("/etc/resolv.conf" , "r")) == NULL)  {   printf("Failed opening /etc/resolv.conf file \n");  }  while(fgets(line , 200 , fp))  {   if(line[0] == '#')   {    continue;   }   if(strncmp(line , "nameserver" , 10) == 0)   {    p = strtok(line , " ");    p = strtok(NULL , " ");    //p now is the dns ip :)    //????   }  }  strcpy(dns_servers[0] , "208.67.222.222");  strcpy(dns_servers[1] , "208.67.220.220"); } /*  * This will convert www.google.com to 3www6google3com  * got it :)  * */ void ChangetoDnsNameFormat(unsigned char* dns,unsigned char* host) {  int lock = 0 , i;  strcat((char*)host,".");  for(i = 0 ; i < strlen((char*)host) ; i++)  {   if(host[i]=='.')   {    *dns++ = i-lock;    for(;lock<i;lock++)    {     *dns++=host[lock];    }    lock++; //or lock=i+1;   }  }  *dns++='\0'; }