Parser seems working for requests

3 files changed, 123 insertions, 35 deletions

diff --git a/src/dns.c b/src/dns.c
index 2d3ac75..eaa032e 100644
--- a/src/dns.c
+++ b/src/dns.c
@@ -7,9 +7,9 @@ int dns_parse_packet ( char* _buffer, int _bufflen, struct dns_message* _msg )
 
 	if ( _bufflen < 12 )
 		return 1; //Too short to contain a DNS header
-	
+
 	//TODO test
-	_msg->header.id = *( (uint16_t*) _buffer );	
+	_msg->header.id = *( (uint16_t*) _buffer );
 	_msg->header.QR =  ( 0x80 & *( (uint8_t*) (_buffer + 2)) ) >> 7;
 	_msg->header.OPCODE = (0x78 & *( (uint8_t*) (_buffer + 2))) >> 3;
 	_msg->header.AA = (0x04 & *( (uint8_t*) (_buffer + 2))) >> 2;
@@ -18,17 +18,41 @@ int dns_parse_packet ( char* _buffer, int _bufflen, struct dns_message* _msg )
 	_msg->header.RA = (0x80 & *( (uint8_t*) (_buffer + 3))) >> 7;
 	_msg->header.Z  = (0x70 & *( (uint8_t*) (_buffer + 3))) >> 4;
 	_msg->header.RCODE = (0x0F & *( (uint8_t*) (_buffer + 3)));
-	_msg->header.question_count	= (*((uint8_t*) (_buffer + 4)) << 8) | *((uint8_t*) (_buffer + 5));
-	_msg->header.answer_count	= (*((uint8_t*) (_buffer + 6)) << 8) | *((uint8_t*) (_buffer + 7));
-	_msg->header.authorative_count	= (*((uint8_t*) (_buffer + 8)) << 8) | *((uint8_t*) (_buffer + 9));
+	_msg->header.question_count	= (*((uint8_t*) (_buffer + 4 )) << 8) | *((uint8_t*) (_buffer + 5 ));
+	_msg->header.answer_count	= (*((uint8_t*) (_buffer + 6 )) << 8) | *((uint8_t*) (_buffer + 7 ));
+	_msg->header.authorative_count	= (*((uint8_t*) (_buffer + 8 )) << 8) | *((uint8_t*) (_buffer + 9 ));
 	_msg->header.additional_count	= (*((uint8_t*) (_buffer + 10)) << 8) | *((uint8_t*) (_buffer + 11));
-
+	//TODO remove
 	printf("ANSWER %i\n", _msg->header.answer_count);
 	printf("QUESTI %i\n", _msg->header.question_count);
 	printf("AUTHOR %i\n", _msg->header.authorative_count);
 	printf("ADDITI %i\n", _msg->header.additional_count);
-	
-	return 1;
+
+	//Allocate question array
+	//TODO Only implements question section.
+	size_t qsize = sizeof(typeof(*(_msg->question))) * _msg->question_count;
+	_msg->question_count = _msg->header.question_count;
+	_msg->question = malloc ( qsize );
+	memset( _msg->question, 0, qsize );
+
+	int ptr = 12; //byte counter
+	for (int i = 0; i < _msg->question_count; i++) {
+		int qname_len = qname_check ( (_buffer + ptr), _bufflen - ptr);
+
+		if (qname_len <= 0) //Check for faulty QNAME
+			return 1;
+
+		_msg->question[i].qname = _buffer + ptr;
+		ptr += qname_len;
+		_msg->question[i].qtype = (uint16_t*) (_buffer + ptr);
+		ptr += 2;
+		_msg->question[i].qclass = (uint16_t*) (_buffer + ptr);
+
+		if( ptr >= _bufflen ) //Out of bounds check
+			return 1;
+	}
+
+	return 0;
 }
 
 int fqdn_to_qname( char* _source, int _sourcelen, char* _sink ,int _sinklen )
@@ -60,7 +84,7 @@ int fqdn_to_qname( char* _source, int _sourcelen, char* _sink ,int _sinklen )
 	_sink[lastdot] = i - lastdot;
 	_sink[i + 1] = 0;
 
-	return i+2; 
+	return i+2;
 }
 
 
@@ -85,8 +109,28 @@ int qname_to_fqdn( char* _source, int _sourcelen, char* _sink, int _sinklen )
 		} else {
 			_sink[i-1] = _source[i];
 		}
+	}
+	return i-1;
+}
+
+int qname_check( char* _source, int _sourcelen )
+{
+	if (!_sourcelen)
+		return -1;
 
+	int next_dot = 0;
+
+	for (int i = 0; i < _sourcelen; i++) {
+		if ( i == next_dot ) {
+			if (_source[i]) { //Not last dot
+				next_dot = _source[i] + i + 1;
+			} else { //last dot
+				return i+1;
+			}
+		} else if (!_source[i]) { //Invalid qname
+			return -1;
+		}
 	}
 
-	return i-1;
+	return -1;
 }
diff --git a/src/dns.h b/src/dns.h
index 8cba804..c2d6d18 100644
--- a/src/dns.h
+++ b/src/dns.h
@@ -1,18 +1,32 @@
 #pragma once
 
 #include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
 
 //TODO remove
 #include <stdio.h>
 
+/**
+ * Data is COPIED
+ * */
 struct dns_header;
 
+/**
+ * Data is REFERENCED
+ * */
 struct dns_question;
 
+/**
+ * Data is REFERENCED
+ * */
 struct dns_answer;
 
 /**
  * DNS Message struct
+ *
+ * A initialized instance is only valid as long as
+ * the buffer used to create it remains unchanged
  * */
 struct dns_message;
 
@@ -35,32 +49,33 @@ struct dns_header {
 };
 
 struct dns_question {
-	char* qname;
-	uint16_t qtype;
-	uint16_t qclass;
+	const char* qname;
+	const uint16_t* qtype;
+	uint16_t* qclass;
 };
 
 struct dns_answer {
 	char* name; //in qname format
-	uint16_t type;
-	uint16_t class;
-	uint32_t ttl;
-	uint16_t rdlength;
+	uint16_t* type;
+	uint16_t* class;
+	uint32_t* ttl;
+	uint16_t* rdlength;
 	char* rdata;
 };
 
 struct dns_message {
 	struct dns_header header;
-	
-	int qcount;
+
+	int question_count;
 	struct dns_question* question;
 
-	int acount;
+	int answer_count;
 	struct dns_answer* answer;
 };
 
 /**
  * Parse the packet in _buffer and populate the dns_message struct
+ * Struct may still be written to on failure but contents are invalid
  * returns: 0 on success, !=0 on failure
  * */
 int dns_parse_packet ( char* _buffer, int _bufflen, struct dns_message* _msg );
@@ -80,3 +95,9 @@ int fqdn_to_qname( char* _source, int _sourcelen, char* _sink, int _sinklen );
  * _sink may still be altered in failed attempts, but not terminated.
  * */
 int qname_to_fqdn( char* _source, int _sourcelen, char* _sink, int _sinklen );
+
+/**
+ * Check a QNAME and get length
+ * returns: length of QNAME including NULL-byte at the end, < 0 on error
+ * */
+int qname_check( char* _source, int _sourcelen );
diff --git a/src/main.c b/src/main.c
index 92ca391..cb0432e 100644
--- a/src/main.c
+++ b/src/main.c
@@ -34,10 +34,29 @@ void signal_term_child ( );
 
 void signal_child ( );
 
-int test_main(	int argc,
+int main1(	int argc,
 		char* argv[] )
 {
 	printf("TEST MODE. NOT FUNCTIONAL\n");
+	
+	/*
+	//Fuzztest the QNAME checker
+	FILE* urand = fopen ("/dev/urandom", "r");
+	char rand[128];
+	char out[129];
+	out[128] = 0;
+
+	if (!urand)
+		return 1;
+
+	for (;;) {
+		if (fread (rand, 128, 1, urand) > 0) {
+			if ( qname_check(rand, 128) > 0 ) {
+				qname_to_fqdn ( rand, 128, out, 128);
+				printf("Valid %s\n", out);
+			}
+		}
+	}*/
 
 	char in[128];
 	char out[128];
@@ -48,6 +67,11 @@ int test_main(	int argc,
 
 	int written = fqdn_to_qname (in,128,out,128);
 
+	if ( qname_check(out,128) < 0)
+		printf("Wrong\n");
+	else
+		printf("qname ok\n");
+
 	if (written < 0) {
 		printf("invallid fqdn\n");
 		return 1;
@@ -57,7 +81,7 @@ int test_main(	int argc,
 		printf(" %x ", out[i]);
 
 	written = qname_to_fqdn (out,128,in,128);
-	
+
 	if (written < 0) {
 		printf("invalid qname\n");
 		return 1;
@@ -72,9 +96,9 @@ int test_main(	int argc,
 int main(	int argc,
 		char* argv[] )
 {
-	int 		ret;
-       	struct		sockaddr_in sock_server_addr;
-	
+	int		ret;
+	struct		sockaddr_in sock_server_addr;
+
 	char recv_buffer[ UDP_BUFFER_LEN ];
 
 	signal ( SIGTERM, signal_term );
@@ -112,7 +136,6 @@ int main(	int argc,
 	{
 		struct 		sockaddr_in sock_client_addr;
 		socklen_t	sock_client_addr_len;
-		pid_t pid;
 
 		sock_client_addr_len = sizeof ( struct sockaddr_in );
 		memset ( &sock_client_addr, '\0', sock_client_addr_len );
@@ -130,7 +153,7 @@ int main(	int argc,
 
 		LOGPRINTF(_LOG_DEBUG, "UDP Packet size %i", ret);
 
-		if ( (pid = handle_connection (sock_server,
+		if ( (handle_connection (sock_server,
 					&sock_client_addr,
 					sock_client_addr_len,
 					recv_buffer,
@@ -155,12 +178,12 @@ int handle_connection (	int _socket,
 			int _bufflen )
 {
 	pid_t pid = fork();
-	
+
 	if ( pid > 0)
 		return 0;
 	else if ( pid < 0 )
 		return errno;
-	
+
 	//Change signal handler. signal_term shuts down entire socket on TERM
 	signal ( SIGTERM, signal_term_child );
 
@@ -169,25 +192,25 @@ int handle_connection (	int _socket,
 
 	//Testing recieved question
 	//TODO remove
-	char out[128];
-	qname_to_fqdn((_buffer+12), _bufflen-12, out, 128);
-	printf("%s\n", out);
 
-	
 	struct dns_message msg;
-	
+
 	if (dns_parse_packet (_buffer, _bufflen, &msg) ) {
 		LOGPRINTF (_LOG_DEBUG, "Malformed packet recieved. parsing failed");
 		close ( _socket );
 		exit( 1 );
 	}
 
+	char out[128];
+	qname_to_fqdn( msg.question[0].qname, 100, out, 128);
+	printf("%s\n", out);
+	
 	exit ( 0 );
 }
 
 void signal_term ( ) {
 	printf( "Recieved Signal. Terminating active connections and closing socket\n" );
-	
+
 	//terminate all children >:)
 	kill ( 0, SIGTERM );