| | |
| | | #include <unistd.h> |
| | | #include "dns.h" |
| | | |
| | | void change_to_DNS_name_format(unsigned char* dns, unsigned char* host); |
| | | char* read_name(unsigned char* reader, unsigned char* buffer, int* count); |
| | | |
| | | // DNS code copied from |
| | | // https://gist.github.com/fffaraz/9d9170b57791c28ccda9255b48315168 |
| | | |
| | |
| | | unsigned char ad :1; //authenticated data |
| | | unsigned char z :1; //reserved for future use |
| | | unsigned char ra :1; //recursion available |
| | | unsigned short q_count; //number of question entries |
| | | unsigned short q_count; //number of question entrise |
| | | unsigned short ans_count; //number of answer entries |
| | | unsigned short auth_count; //number of authority entries |
| | | unsigned short add_count; //number of resource entries |
| | |
| | | /* Pointers to record components */ |
| | | struct RES_RECORD |
| | | { |
| | | unsigned char* name; |
| | | char* name; |
| | | struct R_DATA resource; |
| | | unsigned char* rdata; |
| | | char* rdata; |
| | | }; |
| | | |
| | | void resolve(char* hostname, char* dns_ip, int query_type, int read) |
| | | void resolve(unsigned char* buf, char* hostname, char* dns_ip, int query_type) |
| | | { |
| | | int s, i, j; |
| | | struct sockaddr_in dest, a; |
| | | unsigned char buf[65536], *qname, *reader; |
| | | struct DNS_HEADER* dns = NULL; |
| | | struct QUESTION* qinfo = NULL; |
| | | int s, i; |
| | | struct sockaddr_in dest; |
| | | unsigned char *qname; |
| | | struct DNS_HEADER* dns = (struct DNS_HEADER*)buf; |
| | | struct QUESTION* qinfo; |
| | | |
| | | s = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP); |
| | | dest.sin_family = AF_INET; |
| | |
| | | dest.sin_addr.s_addr = inet_addr(dns_ip); |
| | | |
| | | //dns packet header |
| | | dns = (struct DNS_HEADER*)&buf; |
| | | dns->id = (unsigned short) htons(getpid()); |
| | | dns->qr = 0; //make query |
| | | dns->opcode = 0; //standard query |
| | |
| | | //negative return is a fail |
| | | i = sizeof(dest); |
| | | recvfrom(s, (char*)buf, 65536, 0, (struct sockaddr*)&dest, (socklen_t*)&i); |
| | | |
| | | //read response |
| | | if (read) { |
| | | print_packet(buf); |
| | | } |
| | | return; |
| | | } |
| | | |
| | |
| | | struct RES_RECORD answers[20], auth[20], addit[20]; |
| | | struct DNS_HEADER *dns; |
| | | struct sockaddr_in a; |
| | | char* qname = buf+sizeof(struct DNS_HEADER), *reader; |
| | | unsigned char* qname = buf+sizeof(struct DNS_HEADER), *reader; |
| | | int stop, i, j; |
| | | dns = (struct DNS_HEADER*)buf; |
| | | reader = &buf[sizeof(struct DNS_HEADER)+strlen((const char*)qname)+1+sizeof(struct QUESTION)]; |
| | |
| | | reader = reader+sizeof(struct R_DATA); |
| | | |
| | | if (ntohs(answers[i].resource.type) == T_A) { //IPv4 address |
| | | answers[i].rdata = (unsigned char*)malloc(ntohs(answers[i].resource.data_len)); |
| | | answers[i].rdata = (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]; |
| | | } |
| | |
| | | } else if (ntohs(answers[i].resource.type) == T_CNAME) { //CNAME |
| | | printf("has alias: %s", answers[i].rdata); |
| | | } |
| | | free(answers[i].name); |
| | | free(answers[i].rdata); |
| | | putc('\n', stdout); |
| | | } |
| | |
| | | //print authorities |
| | | printf("Auth recs: %d\n", ntohs(dns->auth_count)); |
| | | for (i = 0; i < ntohs(dns->auth_count); i++) { |
| | | printf("name: %s ", addit[i].name); |
| | | if (ntohs(addit[i].resource.type) == 1) { |
| | | printf("name: %s ", auth[i].name); |
| | | if (ntohs(auth[i].resource.type) == 1) { |
| | | long* p; |
| | | p = (long*)addit[i].rdata; |
| | | p = (long*)auth[i].rdata; |
| | | a.sin_addr.s_addr = *p; |
| | | printf("has IPv4 address: %s", inet_ntoa(a.sin_addr)); |
| | | } |
| | | free(answers[i].name); |
| | | free(auth[i].rdata); |
| | | putc('\n', stdout); |
| | | } |
| | | |
| | | printf("Addit recs: %d\n", ntohs(dns->add_count)); |
| | | for (i = 0; i < ntohs(dns->add_count); i++) { |
| | | printf("name; %s", addit[i].name); |
| | | if (ntohs(auth[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)); |
| | | } else { |
| | | printf("has %s", addit[i].rdata); |
| | | } |
| | | free(answers[i].name); |
| | | free(addit[i].rdata); |
| | | putc('\n', stdout); |
| | | } |
| | | } |
| | | |
| | | |
| | |
| | | { |
| | | int lock = 0; |
| | | char h[300]; |
| | | strcpy(h, host); |
| | | strcpy(h, (char*)host); |
| | | strcat((char*)h,"."); |
| | | |
| | | for (int i = 0; i < strlen((char*)h); i++) { |
| | | for (int i = 0; i < strlen(h); i++) { |
| | | if (h[i] == '.') { |
| | | *dns++ = i-lock; |
| | | for (;lock<i;lock++) { |
| | |
| | | |
| | | char* read_name(unsigned char* reader, unsigned char* buffer, int* count) |
| | | { |
| | | unsigned char* name; |
| | | char* name; |
| | | unsigned int p=0, jumped=0, offset; |
| | | int i, j; |
| | | *count = 1; |
| | | name = (unsigned char*)malloc(256); |
| | | name = (char*)malloc(256); |
| | | name[0]='\0'; |
| | | |
| | | while (*reader != 0) { |