resolv.h

/*
 * Copyright (c) 1983, 1987, 1989 The Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that: (1) source distributions retain this entire copyright
 * notice and comment, and (2) distributions including binaries display
 * the following acknowledgement:  ``This product includes software
 * developed by the University of California, Berkeley and its contributors''
 * in the documentation or other materials provided with the distribution
 * and in all advertising materials mentioning features or use of this
 * software. Neither the name of the University nor the names of its
 * contributors may be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 */


/*
 * Define constants based on rfc883
 */
#define PACKETSZ	512		/* maximum packet size */
#define MAXDNAME	256		/* maximum domain name */
#define MAXCDNAME	255		/* maximum compressed domain name */
#define MAXLABEL	63		/* maximum length of domain label */
	/* Number of bytes of fixed size data in query structure */
#define QFIXEDSZ	4
	/* number of bytes of fixed size data in resource record */
#define RRFIXEDSZ	10

/*
 * Internet nameserver port number
 */
#define NAMESERVER_PORT	53

/*
 * Currently defined opcodes
 */
#define QUERY		0x0		/* standard query */
#define IQUERY		0x1		/* inverse query */
#define STATUS		0x2		/* nameserver status query */

#define NOERROR		0		/* no error */
#define FORMERR		1		/* format error */
#define SERVFAIL	2		/* server failure */
#define NXDOMAIN	3		/* non existent domain */
#define NOTIMP		4		/* not implemented */
#define REFUSED		5		/* query refused */

/*
 * Type values for resources and queries
 */
#define T_A		1		/* host address */
#define T_NS		2		/* authoritative server */
#define T_MD		3		/* mail destination */
#define T_MF		4		/* mail forwarder */
#define T_CNAME		5		/* connonical name */
#define T_SOA		6		/* start of authority zone */
#define T_MB		7		/* mailbox domain name */
#define T_MG		8		/* mail group member */
#define T_MR		9		/* mail rename name */
#define T_NULL		10		/* null resource record */
#define T_WKS		11		/* well known service */
#define T_PTR		12		/* domain name pointer */
#define T_HINFO		13		/* host information */
#define T_MINFO		14		/* mailbox information */
#define T_MX		15		/* mail routing information */
#define T_TXT		16		/* text strings */

/*
 * Values for class field
 */

#define C_IN		1		/* the arpa internet */
/*
 * Status return codes for T_UNSPEC conversion routines
 */
#define CONV_SUCCESS 0
#define CONV_OVERFLOW -1
#define CONV_BADFMT -2
#define CONV_BADCKSUM -3
#define CONV_BADBUFLEN -4

#ifndef BYTE_ORDER
#define	LITTLE_ENDIAN	1234	/* least-significant byte first (vax) */
#define	BIG_ENDIAN	4321	/* most-significant byte first (IBM, net) */
#define	PDP_ENDIAN	3412	/* LSB first in word, MSW first in long (pdp) */

#define BYTE_ORDER	LITTLE_ENDIAN

#endif /* BYTE_ORDER */

/*
 * Structure for query header, the order of the fields is machine and
 * compiler dependent, in our case, the bits within a byte are assignd 
 * least significant first, while the order of transmition is most 
 * significant first.  This requires a somewhat confusing rearrangement.
 */

typedef struct {
	u_short	id;		/* query identification number */
#if BYTE_ORDER == BIG_ENDIAN
			/* fields in third byte */
	u_char	qr:1;		/* response flag */
	u_char	opcode:4;	/* purpose of message */
	u_char	aa:1;		/* authoritive answer */
	u_char	tc:1;		/* truncated message */
	u_char	rd:1;		/* recursion desired */
			/* fields in fourth byte */
	u_char	ra:1;		/* recursion available */
	u_char	pr:1;		/* primary server required (non standard) */
	u_char	unused:2;	/* unused bits */
	u_char	rcode:4;	/* response code */
#endif
#if BYTE_ORDER == LITTLE_ENDIAN || BYTE_ORDER == PDP_ENDIAN
			/* fields in third byte */
	u_char	rd:1;		/* recursion desired */
	u_char	tc:1;		/* truncated message */
	u_char	aa:1;		/* authoritive answer */
	u_char	opcode:4;	/* purpose of message */
	u_char	qr:1;		/* response flag */
			/* fields in fourth byte */
	u_char	rcode:4;	/* response code */
	u_char	unused:2;	/* unused bits */
	u_char	pr:1;		/* primary server required (non standard) */
	u_char	ra:1;		/* recursion available */
#endif
			/* remaining bytes */
	u_short	qdcount;	/* number of question entries */
	u_short	ancount;	/* number of answer entries */
	u_short	nscount;	/* number of authority entries */
	u_short	arcount;	/* number of resource entries */
} HEADER;

/*
 * Defines for handling compressed domain names
 */
#define INDIR_MASK	0xc0

/*
 * Structure for passing resource records around.
 */
struct rrec {
	short	r_zone;			/* zone number */
	short	r_class;		/* class number */
	short	r_type;			/* type number */
	u_long	r_ttl;			/* time to live */
	int	r_size;			/* size of data area */
	char	*r_data;		/* pointer to data */
};

extern	u_short	_getshort();
extern	u_long	_getlong();

/*
 * Inline versions of get/put short/long.
 * Pointer is advanced; we assume that both arguments
 * are lvalues and will already be in registers.
 * cp MUST be u_char *.
 */
#define GETSHORT(s, cp) { \
	(s) = *(cp)++ << 8; \
	(s) |= *(cp)++; \
}

#define GETLONG(l, cp) { \
	(l) = *(cp)++ << 8; \
	(l) |= *(cp)++; (l) <<= 8; \
	(l) |= *(cp)++; (l) <<= 8; \
	(l) |= *(cp)++; \
}


#define PUTSHORT(s, cp) { \
	*(cp)++ = (s) >> 8; \
	*(cp)++ = (s); \
}

/*
 * Warning: PUTLONG destroys its first argument.
 */
#define PUTLONG(l, cp) { \
	(cp)[3] = l; \
	(cp)[2] = (l >>= 8); \
	(cp)[1] = (l >>= 8); \
	(cp)[0] = l >> 8; \
	(cp) += sizeof(u_long); \
}
/*
 * Global defines and variables for resolver stub.
 */

#define	MAXNS		3		/* max # name servers we'll track */
#define	MAXDFLSRCH	3		/* # default domain levels to try */
#define	MAXDNSRCH	6		/* max # default domain levels to try */
#define	LOCALDOMAINPARTS 2		/* min levels in name that is "local" */

#define	RES_TIMEOUT	5		/* seconds between retries */

struct state
{
	int	retrans;  	 	/* retransmition time interval */
	int	retry;			/* number of times to retransmit */
	long	options;		/* option flags - see below. */
	int	nscount;		/* number of name servers */
	struct	sockaddr_in nsaddr_list[MAXNS];	/* address of name server */
#define	nsaddr	nsaddr_list[0]		/* for backward compatibility */
	u_short	id;			/* current packet id */
	char	defdname[MAXDNAME];	/* default domain */
	char	*dnsrch[MAXDNSRCH+1];	/* components of domain to search */
};

#define RES_INIT	0x0001		/* address initialized */
#define RES_DEBUG	0x0002		/* print debug messages */
#define RES_AAONLY	0x0004		/* authoritative answers only */
#define RES_USEVC	0x0008		/* use virtual circuit */
#define RES_PRIMARY	0x0010		/* query primary server only */
#define RES_IGNTC	0x0020		/* ignore trucation errors */
#define RES_RECURSE	0x0040		/* recursion desired */
#define RES_DEFNAMES	0x0080		/* use default domain name */
#define RES_STAYOPEN	0x0100		/* Keep TCP socket open */
#define RES_DNSRCH	0x0200		/* search up local domain tree */

#define RES_DEFAULT	(RES_RECURSE | RES_DEFNAMES | RES_DNSRCH)

extern struct state _res;