#include "platform.h"
#include "gnunet-dns-parser.h"
#include "gnunet-vpn-packet.h"

unsigned int parse_dns_name(unsigned char* d, const unsigned char* src, unsigned short idx) {/*{{{*/
	unsigned char* dest = d;

	int len = src[idx++];
	while (len != 0) {
		if (len & 0xC0) { /* Compressed name, offset in this and the next octet */
			unsigned short offset = ((len & 0x3F) << 8) | src[idx++];
			parse_dns_name(dest, src, offset - 12); /* 12 for the Header of the DNS-Packet, idx starts at 0 which is 12 bytes from the start of the packet */
			return idx;
		}
		memcpy(dest, src+idx, len);
		idx += len;
		dest += len;
		*dest = '.';
		dest++;
		len = src[idx++];
	};
	*dest = 0;

	return idx;
}
/*}}}*/

unsigned short parse_dns_record(unsigned char* data, struct dns_record** dst, unsigned short count, unsigned short idx) {/*{{{*/
	int i;
	unsigned short _idx;
	for (i = 0; i < count; i++) {
		dst[i] = GNUNET_malloc(sizeof(struct dns_record));
		dst[i]->name = alloca(255); // see RFC1035
		unsigned char* name = dst[i]->name;

		_idx = parse_dns_name(name, data, idx);
		dst[i]->namelen = _idx - idx;
		idx = _idx;

		dst[i]->type = *((unsigned short*)(data+idx));
		idx += 2;
		dst[i]->class = *((unsigned short*)(data+idx));
		idx += 2;
		dst[i]->ttl = *((unsigned int*)(data+idx));
		idx += 4;
		dst[i]->data_len = *((unsigned short*)(data+idx));
		idx += 2;
		dst[i]->data = GNUNET_malloc(ntohs(dst[i]->data_len));
		memcpy(dst[i]->data, data+idx, ntohs(dst[i]->data_len));
		idx += ntohs(dst[i]->data_len);
	}
	return idx;
}/*}}}*/

struct dns_pkt_parsed* parse_dns_packet(struct dns_pkt* pkt) {
	struct dns_pkt_parsed* ppkt = GNUNET_malloc(sizeof(struct dns_pkt_parsed));
	memcpy(&ppkt->s, &pkt->s, sizeof pkt->s);

	unsigned short qdcount = ntohs(ppkt->s.qdcount);
	unsigned short ancount = ntohs(ppkt->s.ancount);
	unsigned short nscount = ntohs(ppkt->s.nscount);
	unsigned short arcount = ntohs(ppkt->s.arcount);

	ppkt->queries = GNUNET_malloc(qdcount*sizeof(struct dns_query*));
	ppkt->answers = GNUNET_malloc(ancount*sizeof(struct dns_record*));
	ppkt->nameservers = GNUNET_malloc(nscount*sizeof(struct dns_record*));
	ppkt->additional = GNUNET_malloc(arcount*sizeof(struct dns_record*));

	unsigned short idx = 0, _idx; /* This keeps track how far we have parsed the data */

	int i;
	for (i = 0; i < qdcount; i++) { /*{{{*/
		ppkt->queries[i] = GNUNET_malloc(sizeof(struct dns_query));
		unsigned char* name = alloca(255); /* see RFC1035, it can't be more than this. */

		_idx = parse_dns_name(name, pkt->data, idx);
		ppkt->queries[i]->namelen = _idx - idx;
		idx = _idx;

		ppkt->queries[i]->name = GNUNET_malloc(ppkt->queries[i]->namelen + 1);
		memcpy(ppkt->queries[i]->name, name, ppkt->queries[i]->namelen + 1);

		ppkt->queries[i]->qtype = *((unsigned short*)(pkt->data+idx));
		idx += 2;
		ppkt->queries[i]->qclass = *((unsigned short*)(pkt->data+idx));
		idx += 2;
	}
	/*}}}*/
	idx = parse_dns_record(pkt->data, ppkt->answers, ancount, idx);
	idx = parse_dns_record(pkt->data, ppkt->nameservers, nscount, idx);
	idx = parse_dns_record(pkt->data, ppkt->additional, arcount, idx);
	return ppkt;
}