dns.c

在freescale 的ne64上开发的源代码

				dns_event_listener(DNS_EVENT_ERROR,DNS_ERROR_GENERAL);
				return (-1);
			}

			dns_ancount=(((UINT16)RECEIVE_NETWORK_B())<<8);
			dns_ancount+=RECEIVE_NETWORK_B();

			dns_nscount=(((UINT16)RECEIVE_NETWORK_B())<<8);
			dns_nscount+=RECEIVE_NETWORK_B();

			/* skip ARCOUNT */
			(void)RECEIVE_NETWORK_B();
			(void)RECEIVE_NETWORK_B();

			/* got to the data, let's process it */
			/* check if question section is appropriate (QNAME the same
				and QTYPE=QCLASS=1
			*/
			tmp_ptr=dns_hostptr;
			while((tmp_byte=RECEIVE_NETWORK_B())!=0){
				while((tmp_byte--)!=0){
					if(*tmp_ptr++!=RECEIVE_NETWORK_B()){
						DEBUGOUT("DNS: QNAME not the same!!!! \r\n");
						/* we'll assume that this was from some previous
							query and just exit here */
						return (-1);
					}
				}
				/* reached the end of the label. Is it dot or end of string? */

				if(*tmp_ptr=='\0'){
					continue;
				}

				if(*tmp_ptr++!='.'){
					DEBUGOUT("DNS: DOT not where it's supposed to be!\r\n");
					return (-1);
				}
			}


			/* qtype and qclass */
			tmp_int=(((UINT16)RECEIVE_NETWORK_B())<<8);
			tmp_int+=RECEIVE_NETWORK_B();

			tmp_int|=((UINT16)(RECEIVE_NETWORK_B())<<8);
			tmp_int|=RECEIVE_NETWORK_B();

			if(tmp_int!=0x0001){
				DEBUGOUT("DNS: Question section QTYPE and/or QCLASS not ok!\r\n");
				dns_event_listener(DNS_EVENT_ERROR,DNS_ERROR_GENERAL);
				return (-1);
			}

			/* process all answer RRs and try to find answer */

			/* simply try to find INET class RR. It is
				_PROBABLY_ what we're after. More extensive checking
				would demand buffering the reply which may not be
				desireable.
			 */
			while(dns_ancount||dns_nscount){
				do{
					tmp_byte=RECEIVE_NETWORK_B();
				}while((tmp_byte!=0)&&((tmp_byte&0xc0)!=0xc0));

				if(tmp_byte!=0)	/*second offset byte used in compression*/
					RECEIVE_NETWORK_B();

				/* TYPE */
				tmp_int=((UINT16)RECEIVE_NETWORK_B())<<8;
				tmp_int|=RECEIVE_NETWORK_B();

				/* CLASS */
				tmp_int|=(((UINT16)RECEIVE_NETWORK_B())<<8);
				tmp_int|=RECEIVE_NETWORK_B();

				/* CLASS==INET and TYPE=A ? */
				if(tmp_int==0x0001){

					/* got it. Skip TTL and read RDLENGTH */
					for(tmp_byte=0;tmp_byte<6;tmp_byte++){
						tmp_int=(tmp_int<<8)+RECEIVE_NETWORK_B();
					}

					if(tmp_int==0x0004){
						/* great, read IP address*/
						dns_tmp_ip=((UINT32)RECEIVE_NETWORK_B())<<24;
						dns_tmp_ip+=((UINT32)RECEIVE_NETWORK_B())<<16;
						dns_tmp_ip+=((UINT32)RECEIVE_NETWORK_B())<<8;
						dns_tmp_ip+=RECEIVE_NETWORK_B();

						/* we got some IP address. Is it what we asked for
							or a NS IP addr*/
						if(dns_ancount){
							DEBUGOUT("DNS: Got IP address!\r\n");
							dns_event_listener(DNS_EVENT_SUCCESS,dns_tmp_ip);
							dns_state=DNS_STATE_READY;
						}else{
							DEBUGOUT("DNS: Got auth DNS IP addr!\r\n");
							/* invoke another query to the authority */
							dns_retransmit();
						}

						return 0;
					}else{
						/* nope, skip other bytes */
						while(tmp_int--)
							RECEIVE_NETWORK_B();
					}
				}else{

					DEBUGOUT("DNS: RR.CLASS not INET. Skipping!\r\n");

					/* skip TTL and read RDLENGTH*/
					for(tmp_byte=0;tmp_byte<6;tmp_byte++){
						tmp_int=(tmp_int<<8)+RECEIVE_NETWORK_B();
					}

					/* skip RDATA */
					while(tmp_int--)
						RECEIVE_NETWORK_B();
				}
				/* decrement counters */
				if(dns_ancount)
					dns_ancount--;
				else
					if(dns_nscount)
						dns_nscount--;

			}
			break;

		default:
			DEBUGOUT("DNS: unknown UDP event :-(");
			break;
	}
	return 0;
}

/** \brief Invokes DNS resolver
 * 	\author
 *		\li Vladan Jovanovic ([e-mail])
 *	\date 10.10.2002
 *	\param host_name_ptr Pointer to null-terminated host name to be
 *		resolved
 *	\param listener Pointer to DNS listener function that listens to events
 *		from DNS client. This function takes two parameters: first one can
 *		take a value of #DNS_EVENT_SUCCESS or #DNS_EVENT_ERROR and thus
 *		determine the meaning of the second parameter. If first parameter
 *		is #DNS_EVENT_SUCCESS, second parameter represents requested IP
 *		address. In case of #DNS_EVENT_ERROR, second parameter can be one
 *		of the: #DNS_ERROR_FORMAT, #DNS_ERROR_SERVER_FAILURE,
 *		#DNS_ERROR_NAME_ERROR, #DNS_ERROR_NOT_IMPLEMENTED, #DNS_ERROR_REFUSED,
 *		#DNS_ERROR_TIMEOUT, #DNS_ERROR_GENERAL
 *	\return
 *		\li #DNS_ERROR_BUSY - Signals that DNS is currently processing
 *		another request so it is not possible to process a new one
 *		\li #DNS_ERROR_OVERFLOW -  Network transmit buffer too small to hold
 *		DNS request
 *		\li #DNS_ERROR_LABEL - Label in host name longer than 63 bytes. Error
 *		\li #DNS_ERROR_NAME - Host name longer than 264 bytes. Error
 *
 *	Invoke this function to start name-resolving process. Note that currently
 *	DNS client can process only one request at a time and will not allow
 *	multiple requests.
 *
 *
 */
INT16 get_host_by_name(UINT8 *host_name_ptr, void (*listener)(UINT8 , UINT32 )){

	UINT8 *buf_ptr;
	INT8 i;
	UINT16 total;

	switch(dns_state){

		case DNS_STATE_READY:
			dns_state=DNS_STATE_BUSY;
			dns_hostptr=host_name_ptr;
			dns_event_listener=listener;
			dns_tmp_ip=DNS_SERVER_IP;
			dns_retries=DNS_NUM_RETRIES;
			init_timer(dns_timer,DNS_RESEND_PERIOD*TIMERTIC);
			break;

		case DNS_STATE_BUSY:
			DEBUGOUT("DNS: Error, trying to invoke two DNS requests at the same time!\r\n");
			return	DNS_ERROR_BUSY;


		case DNS_STATE_RESEND:
			if(host_name_ptr!=dns_hostptr){
				DEBUGOUT("DNS: Ptrs different. Can't do that! \r\n");
				return DNS_ERROR_BUSY;
			}
			break;

		default:
			DEBUGOUT("DNS: What am I doing in this state?\r\n");
			RESET_SYSTEM();
	}


	/* OK, create message in the Netbuf transmit buffer */

	buf_ptr=net_buf+UDP_APP_OFFSET;

	/* first the header */
	*((UINT16 *)buf_ptr)=0xAAAA; /* id, fixed for now*/
	buf_ptr+=2;

	*buf_ptr++=0x01;
	*buf_ptr++=0x00;

	/*question count*/
	*buf_ptr++=0x00;
	*buf_ptr++=0x01;

	/* others are zero */
	for(i=0;i<6;i++)
		*buf_ptr++=0x00;

	/* ok, create the question section */
	total=0;

	while((*host_name_ptr)!='\0'){

		/* we are still not at the end. Reserve space for count */
		buf_ptr++;
		i=0;

		while(((*host_name_ptr)!='.')&&((*host_name_ptr)!='\0')){
			i++;
			*buf_ptr++=*host_name_ptr++;
			if(buf_ptr==(net_buf+NETWORK_TX_BUFFER_SIZE)){
				DEBUGOUT("DNS: Buffer overflow!!!\r\n");
				return(DNS_ERROR_OVERFLOW);
			}
		}

		/* label shorter than 63 bytes or less? */
		if((i<=0)||(i>=64)){
			DEBUGOUT("DNS: Label size wrong! Aborting....\r\n");
			return(DNS_ERROR_LABEL);
		}

		/* it seems ok for now. Increase total name length*/
		total+=i;

		if(total>=264){
			DEBUGOUT("DNS: Name size wrong! Aborting....\r\n");
			return(DNS_ERROR_NAME);
		}

		*(buf_ptr-i-1)=i;	/* store label length */

		/* ok, where are we ? */
		if((*host_name_ptr)=='.'){
			/* still not at the end, skip dot */
			host_name_ptr++;
		}else
			if((*host_name_ptr)=='\0'){
				/* OHO, finished,
					add ZERO,QTYPE and QCLASS */
				*buf_ptr++=0x00;
				*buf_ptr++=0x00;
				*buf_ptr++=0x01;
				*buf_ptr++=0x00;
				*buf_ptr++=0x01;
				kick_WD();
				/* ok, now send the request */
				return udp_send(dns_socket,dns_tmp_ip,DNS_UDP_PORT,net_buf+UDP_APP_OFFSET,NETWORK_TX_BUFFER_SIZE-UDP_APP_OFFSET,buf_ptr-(net_buf+UDP_APP_OFFSET));
			}
	}
}

#endif