parse a DNS header!

include/dns_packet_buffer.h

@@ -5,7 +5,7 @@
 #define PB_OUT_OF_BOUNDS 9999;
 
 struct DNSPacketBuffer {
-    char buf[PB_SIZE];
+    unsigned char buf[PB_SIZE];
     size_t pos;
 };
 
@@ -13,4 +13,4 @@ struct DNSPacketBuffer *new_dns_packet_buffer();
 
 struct DNSPacketHeader *dns_header(struct DNSPacketBuffer);
 
-char pb_read_byte(struct DNSPacketBuffer *);
+unsigned char pb_read_byte(struct DNSPacketBuffer *);

include/dns_packets.h

@@ -1,6 +1,7 @@
 #pragma once
 #include <stddef.h>
 
+#define DNS_HEADER_BYTES 12
 
 struct DNSPacketHeader {
     /*
@@ -8,14 +9,34 @@ struct DNSPacketHeader {
      * a random ID is assigned to query packets.
      * Response packets must contain the same ID as the query.
      */
-    size_t packet_id : 16;
+    unsigned int packet_id : 16;
+    
+    /*
+     * RD (Recursion Desired)
+     * if set by the client, the server should
+     * attempt to resolve the query recursively
+     * 
+     * the server may not allow recursive resolution.
+     * (see RA / Recursion Available)
+     */
+    unsigned int recursion_desired : 1;
 
     /*
-     * QR (Query/Response)
-     * 0 if the packet is a query
-     * 1 if the packet is a response
+     * TC (Truncated)
+     * if true, this message was truncated.
+     * usually happens when the response payload
+     * is larger than the max UDP packet size
+     *
+     * if set, the query may be re-issued over TCP for the full payload.
      */
-    size_t is_response : 1;
+    unsigned int is_truncated : 1;
+
+    /*
+     * AA (Authoritative Answer)
+     * 
+     * 1 if the responding server is authoritative for the queried domain
+     */
+    unsigned int is_authoritative : 1;
 
     /*
      * OPCODE (Operation Code)
@@ -27,51 +48,14 @@ struct DNSPacketHeader {
      *
      * almost always will be 0
      */
-    size_t opcode : 4;
+    unsigned int opcode : 4;
 
     /*
-     * AA (Authoritative Answer)
-     * 
-     * 1 if the responding server is authoritative for the queried domain
+     * QR (Query/Response)
+     * 0 if the packet is a query
+     * 1 if the packet is a response
      */
-    size_t is_authoritative : 1;
-
-    /*
-     * TC (Truncated)
-     * if true, this message was truncated.
-     * usually happens when the response payload
-     * is larger than the max UDP packet size
-     *
-     * if set, the query may be re-issued over TCP for the full payload.
-     */
-    size_t is_truncated : 1;
-
-    /*
-     * RD (Recursion Desired)
-     * if set by the client, the server should
-     * attempt to resolve the query recursively
-     * 
-     * the server may not allow recursive resolution.
-     * (see RA / Recursion Available)
-     */
-    size_t recursion_desired : 1;
-
-
-    /*
-     * RA (Recursion Available)
-     * if set by the server, incicates that the server allows
-     * recursive queries.
-     */
-    size_t recursion_available : 1;   
-
-    /*
-     * Z (Reserved)
-     * in the original spec, this is reserved for future use.
-     *
-     * in later RFCs, it is used for DNSSEC queries.
-     * (to be implemented)
-     */
-    size_t z : 3;
+    unsigned int is_response : 1;
 
     /*
      * RCODE (Response Code)
@@ -86,31 +70,47 @@ struct DNSPacketHeader {
      * 5    - Refused - the nameserver refuses to perform the requested operation. for example, it may refuse a zone transfer.
      * 6-15 - Reserved for future use
      */
-    size_t response_code : 4;
+    unsigned int response_code : 4;
+
+    /*
+     * Z (Reserved)
+     * in the original spec, this is reserved for future use.
+     *
+     * in later RFCs, it is used for DNSSEC queries.
+     * (to be implemented)
+     */
+    unsigned int z : 3;
+
+    /*
+     * RA (Recursion Available)
+     * if set by the server, incicates that the server allows
+     * recursive queries.
+     */
+    unsigned int recursion_available : 1;   
 
     /*
      * QDCOUNT (Question Count)
      * the number of entries in the question section
      */
-    size_t question_count : 16;
+    unsigned int question_count : 16;
 
     /*
      * ANCOUNT (Answer Count)
      * the number of entries in the answer section
      */
-    size_t answer_count : 16;
+    unsigned int answer_count : 16;
 
     /*
      * NSCOUNT (Nameserver Count)
      * the number of entries in the authority records section
      */
-    size_t ns_count : 16;
+    unsigned int ns_count : 16;
 
     /*
      * ARCOUNT (Additional Records Count)
      * the number of entries in the additional records section
      */
-    size_t ar_count : 16;
+    unsigned int ar_count : 16;
 };
 
 
@@ -125,26 +125,26 @@ struct RecordPreamble {
      * TYPE
      * the record type
      */
-    size_t type : 16;
+    unsigned int type : 16;
 
     /*
      * CLASS
      * specifies the class of the data in the RDATA field.
      * in practice, always set to 1
      */
-    size_t class : 16;
+    unsigned int class : 16;
 
     /*
      * TTL (Time-To-Live)
      * how long a record can be cached before it should be requeried.
      */
-    size_t ttl : 32;
+    unsigned int ttl : 32;
 
     /*
      * RDLENGTH (Record Data Length)
      * length of the record-type-specific data.
      */
-    size_t rd_data_length: 16;
+    unsigned int rd_data_length: 16;
 };
 
 /*
@@ -153,5 +153,5 @@ struct RecordPreamble {
  */
 struct ARecord {
     struct RecordPreamble preamble;
-    size_t ip : 32;
+    unsigned int ip : 32;
 };

include/dns_request.h

@@ -7,4 +7,4 @@ struct DNSRequest {
     struct DNSPacketHeader *header;
 };
 
-struct DNSRequest *new_dns_request(struct DNSPacketBuffer *pb);
+struct DNSRequest *parse_dns_query(struct DNSPacketBuffer *pb);