#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;
+/**
+ * Parse a name from DNS to a normal .-delimited, 0-terminated string.
+ *
+ * @param d The destination of the name. Should have at least 255 bytes allocated.
+ * @param src The DNS-Packet
+ * @param idx The offset inside the Packet from which on the name should be read
+ * @returns The offset of the first unparsed byte (the byte right behind the name)
+ */
+static unsigned int
+parse_dns_name(char* d, const unsigned char* src, unsigned short idx) {/*{{{*/
+ 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;
}
/*}}}*/
+
+/**
+ * Parse a complete DNS-Record from raw DNS-data to a struct dns_record
+ *
+ * @param data The DNS-data
+ * @param dst Pointer to count pointers; individual pointers will be allocated
+ * @param count Number of records to parse
+ * @param idx The offset inside the Packet from which on the name should be read
+ * @returns The offset of the first unparsed byte (the byte right behind the last record)
+ */
+static 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, no name can be longer than this.
+ char* name = dst[i]->name;
+
+ _idx = parse_dns_name(name, data, idx);
+ dst[i]->namelen = _idx - idx;
+
+ dst[i]->name = GNUNET_malloc(dst[i]->namelen);
+ memcpy(dst[i]->name, name, dst[i]->namelen);
+
+ 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;
+}/*}}}*/
+
+/**
+ * Parse a raw DNS-Packet into an usable struct
+ */
+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 */
+
+ /* Parse the Query */
+ int i;
+ for (i = 0; i < qdcount; i++)
+ { /*{{{*/
+ ppkt->queries[i] = GNUNET_malloc(sizeof(struct dns_query));
+ 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);
+ memcpy(ppkt->queries[i]->name, name, ppkt->queries[i]->namelen);
+
+ 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;
+}/*}}}*/
+
+void
+free_parsed_dns_packet(struct dns_pkt_parsed* ppkt) {
+ 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);
+
+ int i;
+ for (i = 0; i < qdcount; i++) {
+ GNUNET_free(ppkt->queries[i]->name);
+ GNUNET_free(ppkt->queries[i]);
+ }
+ GNUNET_free(ppkt->queries);
+ for (i = 0; i < ancount; i++) {
+ GNUNET_free(ppkt->answers[i]->name);
+ GNUNET_free(ppkt->answers[i]->data);
+ GNUNET_free(ppkt->answers[i]);
+ }
+ GNUNET_free(ppkt->answers);
+ for (i = 0; i < nscount; i++) {
+ GNUNET_free(ppkt->nameservers[i]->name);
+ GNUNET_free(ppkt->nameservers[i]->data);
+ GNUNET_free(ppkt->nameservers[i]);
+ }
+ GNUNET_free(ppkt->nameservers);
+ for (i = 0; i < arcount; i++) {
+ GNUNET_free(ppkt->additional[i]->name);
+ GNUNET_free(ppkt->additional[i]->data);
+ GNUNET_free(ppkt->additional[i]);
+ }
+ GNUNET_free(ppkt->additional);
+ GNUNET_free(ppkt);
+}
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