construct answer/question

5 files changed, 130 insertions, 16 deletions

diff --git a/src/dns.c b/src/dns.c
index 2bf6add..01fe7fa 100644
--- a/src/dns.c
+++ b/src/dns.c
@@ -5,7 +5,7 @@
 
 #include "dns.h"
 
-int dns_construct_header ( struct dns_header* _header, char* _buffer, int _bufflen )
+int dns_construct_header ( char* _buffer, int _bufflen, struct dns_header* _header )
 {
 	if ( !_buffer || !_header || _bufflen < 12 )
 		return -1;
@@ -29,6 +29,72 @@ int dns_construct_header ( struct dns_header* _header, char* _buffer, int _buffl
 	return 12;
 }
 
+int dns_construct_answer (
+		char*	_buffer,
+		int	_bufflen,
+		struct	dns_answer* _answer
+		) {
+	int ret = 0;
+
+	if ( !_buffer || _bufflen <= 0 || !_answer )
+		return -1;
+
+	// Check buffer size
+	if ( _answer->qname_len + _answer->rdlength + 10 > _bufflen )
+		return -1;
+
+	memcpy( _buffer, _answer->qname, _answer->qname_len );
+	ret += _answer->qname_len;
+
+	*((uint16_t*)(_buffer + ret + 0 )) = FLIP_BYTES(_answer->type);
+	*((uint16_t*)(_buffer + ret + 2 )) = FLIP_BYTES(_answer->class);
+	*((uint16_t*)(_buffer + ret + 4 )) = FLIP_BYTES((uint16_t)((_answer->ttl << 16) & 0xffff));
+	*((uint16_t*)(_buffer + ret + 6 )) = FLIP_BYTES((uint16_t)(_answer->ttl & 0xffff));
+	*((uint16_t*)(_buffer + ret + 8 )) = FLIP_BYTES(_answer->rdlength);
+	ret += 10;
+
+	memcpy( _buffer + ret, _answer->rdata, _answer->rdlength );
+	ret += _answer->rdlength;
+
+	return ret;
+}
+
+int dns_construct_questoin (
+		char*	_buffer,
+		int	_bufflen,
+		struct	dns_question* _question
+		) {
+	//TODO Test
+	int ret = 0;
+
+	if ( !_buffer || _bufflen <= 0 || !_question )
+		return -1;
+
+	// Check buffer size
+	if ( _question->qname_len + 4 > _bufflen )
+		return -1;
+
+	memcpy( _buffer, _question->qname, _question->qname_len );
+	ret += _question->qname_len;
+
+	*((uint16_t*)(_buffer + ret + 0 )) = FLIP_BYTES(_question->qtype);
+	*((uint16_t*)(_buffer + ret + 2 )) = FLIP_BYTES(_question->qclass);
+	ret += 4;
+
+	return ret;
+}
+
+
+// Question and answer count come from header
+int dns_construct_packet (
+		char*	_buffer,
+		int	_bufflen,
+		struct dns_message* _message
+		) {
+	return -1;
+}
+
+
 int dns_destroy_struct ( struct dns_message* _msg )
 {
 	if ( !_msg )
@@ -77,7 +143,8 @@ int dns_parse_packet ( char* _buffer, int _bufflen, struct dns_message* _msg )
 	printf("QUESTI %i\n", _msg->header.question_count);
 	printf("AUTHOR %i\n", _msg->header.authorative_count);
 	printf("ADDITI %i\n", _msg->header.additional_count);
-*/
+	*/
+
 	//Check for sensible QD, AN, NS and ARCOUNTS before massive memory allocation
 	if(	_msg->header.question_count > 4 ||
 		_msg->header.answer_count > 32 ||
@@ -97,6 +164,8 @@ int dns_parse_packet ( char* _buffer, int _bufflen, struct dns_message* _msg )
 		return 1;
 
 	int ptr = 12; //byte counter
+
+	// TODO refactor
 	for (int i = 0; i < _msg->question_count; i++) {
 		int qname_len = qname_check ( (_buffer + ptr), _bufflen - ptr);
 
@@ -104,6 +173,7 @@ int dns_parse_packet ( char* _buffer, int _bufflen, struct dns_message* _msg )
 			return 1;
 
 		_msg->question[i].qname = _buffer + ptr;
+		_msg->question[i].qname_len = qname_len;
 		ptr += qname_len;
 
 		if( ptr >= (_bufflen - 4) ) //Out of bounds check
diff --git a/src/dns.h b/src/dns.h
index 73cf9c3..c44fb29 100644
--- a/src/dns.h
+++ b/src/dns.h
@@ -91,8 +91,9 @@ struct dns_answer;
 /**
  * DNS Message struct
  *
- * A initialized instance is only valid as long as
- * the buffer used to create it remains unchanged
+ * An initialized instance is only valid as long as
+ * the buffer used to create it remains unchanged as
+ * some values are referenced, not copied.
  * */
 struct dns_message;
 
@@ -116,12 +117,16 @@ struct dns_header {
 
 struct dns_question {
 	const char* qname;
+	int qname_len;
+
 	uint16_t qtype;
 	uint16_t qclass;
 };
 
 struct dns_answer {
-	char* name; //in qname format
+	char* qname; //in qname format
+	int qname_len;
+
 	uint16_t type;
 	uint16_t class;
 	uint32_t ttl;
@@ -140,9 +145,28 @@ struct dns_message {
 };
 
 int dns_construct_header (
-		struct	dns_header* _header,
 		char*	_buffer,
-		int	_bufflen
+		int	_bufflen,
+		struct	dns_header* _header
+		);
+
+int dns_construct_answer (
+		char*	_buffer,
+		int	_bufflen,
+		struct	dns_answer* _answer
+		);
+
+int dns_construct_questoin (
+		char*	_buffer,
+		int	_bufflen,
+		struct	dns_question* _question
+		);
+
+// Question and answer count come from header
+int dns_construct_packet (
+		char*	_buffer,
+		int	_bufflen,
+		struct dns_message* _message
 		);
 
 /**
diff --git a/src/main.c b/src/main.c
index 848f04e..36a37c6 100644
--- a/src/main.c
+++ b/src/main.c
@@ -20,7 +20,11 @@ int main(int argc, char* argv[])
 #ifdef _TEST
 	run_test();
 #else
-	run_dns_server();
+	server_config_t config;
+	config.bind_ip = "0.0.0.0";
+	config.bind_port = 53;
+
+	run_dns_server( &config );
 #endif
 
 }
diff --git a/src/server.c b/src/server.c
index 1b28b14..3ec6603 100644
--- a/src/server.c
+++ b/src/server.c
@@ -5,7 +5,7 @@
 
 #include "server.h"
 
-void run_dns_server ( void )
+void run_dns_server ( server_config_t* _config )
 {
 	int		ret;
 	struct		sockaddr_in sock_server_addr;
@@ -21,6 +21,8 @@ void run_dns_server ( void )
 
 	log_init_stdout ( _LOG_DEBUG );
 
+	LOGPRINTF(_LOG_NOTE, "Initializing DNS Server on %s:%i", _config->bind_ip, _config->bind_port);
+
 	sock_server = socket ( AF_INET, SOCK_DGRAM, 0 );
 	if ( sock_server == -1 ) {
 		LOGPRINTF(_LOG_ERROR, "socket() failed");
@@ -29,8 +31,8 @@ void run_dns_server ( void )
 
 	memset( &sock_server_addr, '\0', sizeof(struct sockaddr_in) );
 	sock_server_addr.sin_family = AF_INET;
-	sock_server_addr.sin_port   = htons( 53 );
-	ret = inet_aton ( "0.0.0.0", & sock_server_addr.sin_addr );
+	sock_server_addr.sin_port   = htons( _config->bind_port );
+	ret = inet_aton ( _config->bind_ip, & sock_server_addr.sin_addr );
 	if( ret == 0 ) { //Error on 0, no errno!
 		LOGPRINTF(_LOG_NOTE, "inet_aton(): Invalid bind IP\n" );
 		exit ( 1 );
@@ -44,6 +46,8 @@ void run_dns_server ( void )
 		exit ( errno );
 	}
 
+	LOGPRINTF(_LOG_NOTE, "Done!");
+
 	while( 1 )
 	{
 		struct 		sockaddr_in sock_client_addr;
@@ -95,10 +99,16 @@ int handle_connection (	int _socket,
 	}
 
 	//Always return NXDOMAIN
-	struct dns_header head = {msg.header.id,1,OP_Q,0,0,0,0,0,NAMEERR,0,0,0,0};
-	char ret[20];
-	int retlen = dns_construct_header ( &head, ret, 20 );
-	sendto (_socket, ret, retlen, 0, (struct sockaddr*) sockaddr_client, sockaddr_client_len);
+
+	struct dns_question quest = & msg.question[0];
+
+	struct dns_header head = {msg.header.id,1,OP_Q,0,0,0,0,0,dns_responsecode.NOERR,0,0,0,0};
+	struct dns_answer answ = {quest->qname, quest->qname_len, }
+
+	char ret[512];
+	int hlen = dns_construct_header ( ret, 512, &head );
+	int alen = dns_construct_answer ( ret + hlen, 512-hlen, &answer );
+	sendto (_socket, ret, hlen + alen, 0, (struct sockaddr*) sockaddr_client, sockaddr_client_len);
 
 	dns_destroy_struct ( &msg );
 
diff --git a/src/server.h b/src/server.h
index 388dbae..d59eba6 100644
--- a/src/server.h
+++ b/src/server.h
@@ -9,6 +9,7 @@
 #include <stdlib.h>
 #include <errno.h>
 #include <string.h>
+#include <stdint.h>
 #include <sys/types.h>
 
 #include <sys/socket.h>
@@ -24,9 +25,14 @@
 
 #define UDP_BUFFER_LEN 512
 
+typedef struct server_config {
+	char* bind_ip;
+	uint16_t bind_port;
+} server_config_t;
+
 static int sock_server;
 
-void run_dns_server ( void );
+void run_dns_server ( server_config_t* _config );
 
 int handle_connection (	int _socket,
 			struct sockaddr_in *sockaddr_client,