NS Utilities

Detailed Description

Collection of utilities for working with DNS queries. These utilities were copied from glibc then modified.

Data Structures
struct	rip_ns_header_s

Macros
#define	RIP_NS_PACKETSZ   512
#define	RIP_NS_UDP_MAXMSG   4096
#define	RIP_NS_MAXMSG   65535
#define	RIP_NS_MAXCDNAME   255
#define	RIP_NS_MAXLABEL   63
#define	RIP_NS_QFIXEDSZ   4
#define	RIP_NS_RRFIXEDSZ   10
#define	RIP_NS_INT32SZ   4
#define	RIP_NS_INT16SZ   2
#define	RIP_NS_INT8SZ   1
#define	RIP_NS_INADDRSZ   4
#define	RIP_NS_IN6ADDRSZ   16
#define	RIP_NS_CMPRSFLGS   0xc0
#define	RIP_NS_RESP_MAX_ANSW   128
#define	RIP_NS_RESP_MAX_NS   16
#define	RIP_NS_RESP_MAX_ADDL   128
#define	RIP_NS_CDNAME_COMP_BUF_LEN   256
#define	RIP_NS_QUERY_SET_END_CODE_AND_RETURN(q, c)
#define	RIP_NS_GET16(s, cp)
#define	RIP_NS_PUT16(s, cp)
#define	RIP_NS_GET32(l, cp)
#define	RIP_NS_PUT32(l, cp)

Typedefs
typedef enum rip_ns_flag_e	rip_ns_flag_t
typedef enum rip_ns_opcode_e	rip_ns_opcode_t
typedef enum rip_ns_rcode_e	rip_ns_rcode_t
typedef enum rip_ns_type_e	rip_ns_type_t
typedef enum rip_ns_class_e	rip_ns_class_t
typedef enum rip_ns_ext_opt_code_e	rip_ns_ext_opt_code_t
typedef struct rip_ns_header_s	rip_ns_header_t

Enumerations
enum	rip_ns_flag_e {   rip_ns_f_qr , rip_ns_f_opcode , rip_ns_f_aa , rip_ns_f_tc ,   rip_ns_f_rd , rip_ns_f_ra , rip_ns_f_z , rip_ns_f_ad ,   rip_ns_f_cd , rip_ns_f_rcode , rip_ns_f_max }
enum	rip_ns_opcode_e {   rip_ns_o_query = 0 , rip_ns_o_iquery = 1 , rip_ns_o_status = 2 , rip_ns_o_notify = 4 ,   rip_ns_o_update = 5 , rip_ns_o_max = 6 }
enum	rip_ns_rcode_e {   rip_ns_r_noerror = 0 , rip_ns_r_formerr = 1 , rip_ns_r_servfail = 2 , rip_ns_r_nxdomain = 3 ,   rip_ns_r_notimpl = 4 , rip_ns_r_refused = 5 , rip_ns_r_yxdomain = 6 , rip_ns_r_yxrrset = 7 ,   rip_ns_r_nxrrset = 8 , rip_ns_r_notauth = 9 , rip_ns_r_notzone = 10 , rip_ns_r_max = 11 ,   rip_ns_r_badvers = 16 , rip_ns_r_badsig = 16 , rip_ns_r_badkey = 17 , rip_ns_r_badtime = 18 ,   rip_ns_r_rip_unknown = -1 , rip_ns_r_rip_shortheader = -2 , rip_ns_r_rip_toolarge = -3 , rip_ns_r_rip_query_tc = -4 ,   rip_ns_r_rip_pack_rr_err = -5 , rip_ns_r_rip_tcp_write_err = -6 , rip_ns_r_rip_tcp_write_close = -7 }
enum	rip_ns_type_e {   rip_ns_t_invalid = 0 , rip_ns_t_a = 1 , rip_ns_t_ns = 2 , rip_ns_t_md = 3 ,   rip_ns_t_mf = 4 , rip_ns_t_cname = 5 , rip_ns_t_soa = 6 , rip_ns_t_mb = 7 ,   rip_ns_t_mg = 8 , rip_ns_t_mr = 9 , rip_ns_t_null = 10 , rip_ns_t_wks = 11 ,   rip_ns_t_ptr = 12 , rip_ns_t_hinfo = 13 , rip_ns_t_minfo = 14 , rip_ns_t_mx = 15 ,   rip_ns_t_txt = 16 , rip_ns_t_rp = 17 , rip_ns_t_afsdb = 18 , rip_ns_t_x25 = 19 ,   rip_ns_t_isdn = 20 , rip_ns_t_rt = 21 , rip_ns_t_nsap = 22 , rip_ns_t_nsap_ptr = 23 ,   rip_ns_t_sig = 24 , rip_ns_t_key = 25 , rip_ns_t_px = 26 , rip_ns_t_gpos = 27 ,   rip_ns_t_aaaa = 28 , rip_ns_t_loc = 29 , rip_ns_t_nxt = 30 , rip_ns_t_eid = 31 ,   rip_ns_t_nimloc = 32 , rip_ns_t_srv = 33 , rip_ns_t_atma = 34 , rip_ns_t_naptr = 35 ,   rip_ns_t_kx = 36 , rip_ns_t_cert = 37 , rip_ns_t_a6 = 38 , rip_ns_t_dname = 39 ,   rip_ns_t_sink = 40 , rip_ns_t_opt = 41 , rip_ns_t_apl = 42 , rip_ns_t_ds = 43 ,   rip_ns_t_sshfp = 44 , rip_ns_t_ipseckey = 45 , rip_ns_t_rrsig = 46 , rip_ns_t_nsec = 47 ,   rip_ns_t_dnskey = 48 , rip_ns_t_dhcid = 49 , rip_ns_t_nsec3 = 50 , rip_ns_t_nsec3param = 51 ,   rip_ns_t_tlsa = 52 , rip_ns_t_smimea = 53 , rip_ns_t_hip = 55 , rip_ns_t_ninfo = 56 ,   rip_ns_t_rkey = 57 , rip_ns_t_talink = 58 , rip_ns_t_cds = 59 , rip_ns_t_cdnskey = 60 ,   rip_ns_t_openpgpkey = 61 , rip_ns_t_csync = 62 , rip_ns_t_spf = 99 , rip_ns_t_uinfo = 100 ,   rip_ns_t_uid = 101 , rip_ns_t_gid = 102 , rip_ns_t_unspec = 103 , rip_ns_t_nid = 104 ,   rip_ns_t_l32 = 105 , rip_ns_t_l64 = 106 , rip_ns_t_lp = 107 , rip_ns_t_eui48 = 108 ,   rip_ns_t_eui64 = 109 , rip_ns_t_tkey = 249 , rip_ns_t_tsig = 250 , rip_ns_t_ixfr = 251 ,   rip_ns_t_axfr = 252 , rip_ns_t_mailb = 253 , rip_ns_t_maila = 254 , rip_ns_t_any = 255 ,   rip_ns_t_uri = 256 , rip_ns_t_caa = 257 , rip_ns_t_avc = 258 , rip_ns_t_ta = 32768 ,   rip_ns_t_dlv = 32769 , rip_ns_t_max = 65536 }
enum	rip_ns_class_e {   rip_ns_c_invalid = 0 , rip_ns_c_in = 1 , rip_ns_c_2 = 2 , rip_ns_c_chaos = 3 ,   rip_ns_c_hs = 4 , rip_ns_c_none = 254 , rip_ns_c_any = 255 , rip_ns_c_max = 65536 }
enum	rip_ns_ext_opt_code_e { rip_ns_ext_opt_c_cs = 8 }

Functions
const char *	rip_ns_class_to_str (rip_ns_class_t class)
const char *	rip_ns_rr_type_to_str (rip_ns_type_t type)
bool	rip_ns_rr_type_supported (uint16_t query_type)
bool	rip_ns_rr_class_supported (uint16_t query_class)
void	rip_ns_put16 (unsigned char *dst, uint16_t num)
int	rip_ns_name_unpack (const unsigned char *msg, const unsigned char *eom, const unsigned char *src, unsigned char *dst, size_t dstsiz)
int	rip_ns_name_pack (const unsigned char *src, unsigned char *dst, int dstsiz, const unsigned char **dnptrs, const unsigned char **lastdnptr)
int	rip_ns_name_pton (const unsigned char *src, unsigned char *dst, size_t dstsiz)
int	rip_ns_name_ntop (const unsigned char *src, char *dst, size_t dstsiz)
int	rip_rr_name_get (const unsigned char *msg, const unsigned char *eom, const unsigned char *src, unsigned char *dst, size_t dstsiz, uint16_t *query_label_len)
int	rip_ns_name_put (const unsigned char *src, unsigned char *dst, int dstsiz, const unsigned char **dnptrs, const unsigned char **lastdnptr)

Macro Definition Documentation

RIP_NS_CDNAME_COMP_BUF_LEN

#define RIP_NS_CDNAME_COMP_BUF_LEN   256

size of buffer used to compress CDNAME.

RIP_NS_CMPRSFLGS

#define RIP_NS_CMPRSFLGS   0xc0

Flag bits indicating name compression.

RIP_NS_GET16

#define RIP_NS_GET16	(		s,
			cp
	)

Value:

    do { \
    const unsigned char *t_cp = (const unsigned char *)(cp); \
    (s) = ((uint16_t)t_cp[0] << 8) \
        | ((uint16_t)t_cp[1]) \
        ; \
    (cp) += RIP_NS_INT16SZ; \
} while (0)

Get a network order unsigned 16 bit integer from buffer "cp" and store it in "s" in host order. "cp" pointer is advanced by 2 bytes.

RIP_NS_GET32

#define RIP_NS_GET32	(		l,
			cp
	)

Value:

    do { \
    const unsigned char *t_cp = (const unsigned char *)(cp); \
    (l) = ((uint32_t)t_cp[0] << 24) \
        | ((uint32_t)t_cp[1] << 16) \
        | ((uint32_t)t_cp[2] << 8) \
        | ((uint32_t)t_cp[3]) \
        ; \
    (cp) += RIP_NS_INT32SZ; \
} while (0)

Get a network order unsigned 32 bit integer from buffer "cp" and store it in "l" in host order. "cp" pointer is advanced by 4 bytes.

RIP_NS_IN6ADDRSZ

#define RIP_NS_IN6ADDRSZ   16

IPv6 T_AAAA

RIP_NS_INADDRSZ

#define RIP_NS_INADDRSZ   4

IPv4 T_A

RIP_NS_INT16SZ

#define RIP_NS_INT16SZ   2

#/bytes of data in a uint16_t

RIP_NS_INT32SZ

#define RIP_NS_INT32SZ   4

#/bytes of data in a uint32_t

RIP_NS_INT8SZ

#define RIP_NS_INT8SZ   1

#/bytes of data in a uint8_t

RIP_NS_MAXCDNAME

#define RIP_NS_MAXCDNAME   255

maximum compressed domain name

RIP_NS_MAXLABEL

#define RIP_NS_MAXLABEL   63

maximum length of domain label

RIP_NS_MAXMSG

#define RIP_NS_MAXMSG   65535

maximum message size

RIP_NS_PACKETSZ

#define RIP_NS_PACKETSZ   512

Define constants based on RFC 883, RFC 1034, RFC 1035 default UDP packet size

RIP_NS_PUT16

#define RIP_NS_PUT16	(		s,
			cp
	)

Value:

    do { \
    uint16_t t_s = (uint16_t)(s); \
    unsigned char *t_cp = (unsigned char *)(cp); \
    *t_cp++ = t_s >> 8; \
    *t_cp   = t_s; \
    (cp) += RIP_NS_INT16SZ; \
} while (0)

Pack an unsigned 16 bit integer "s" in host order into buffer "cp" in network order. "cp" pointer is advanced by 2 bytes.

RIP_NS_PUT32

#define RIP_NS_PUT32	(		l,
			cp
	)

Value:

    do { \
    uint32_t t_l = (uint32_t)(l); \
    unsigned char *t_cp = (unsigned char *)(cp); \
    *t_cp++ = t_l >> 24; \
    *t_cp++ = t_l >> 16; \
    *t_cp++ = t_l >> 8; \
    *t_cp   = t_l; \
    (cp) += RIP_NS_INT32SZ; \
} while (0)

Pack an unsigned 32 bit integer "l" in host order into buffer "cp" in network order. "cp" pointer is advanced by 4 bytes.

RIP_NS_QFIXEDSZ

#define RIP_NS_QFIXEDSZ   4

#/bytes of fixed data in query

RIP_NS_QUERY_SET_END_CODE_AND_RETURN

#define RIP_NS_QUERY_SET_END_CODE_AND_RETURN	(		q,
			c
	)

Value:

    do { \
    (q)->end_code = c; \
    return; \
} while (0)

Macro to set a query code and return from function. This is useful when handling a query and we want to: set query end code and stop any further processing.

RIP_NS_RESP_MAX_ADDL

#define RIP_NS_RESP_MAX_ADDL   128

Maximum number of additional record query response could have, excluding EDNS.

RIP_NS_RESP_MAX_ANSW

#define RIP_NS_RESP_MAX_ANSW   128

Maximum number of answer record query response could have.

RIP_NS_RESP_MAX_NS

#define RIP_NS_RESP_MAX_NS   16

Maximum number of authority record query response could have.

RIP_NS_RRFIXEDSZ

#define RIP_NS_RRFIXEDSZ   10

#/bytes of fixed data in r record

RIP_NS_UDP_MAXMSG

#define RIP_NS_UDP_MAXMSG   4096

maximum UDP response message size

Typedef Documentation

rip_ns_class_t

typedef enum rip_ns_class_e rip_ns_class_t

Values for DNS resource record class field

rip_ns_ext_opt_code_t

typedef enum rip_ns_ext_opt_code_e rip_ns_ext_opt_code_t

EDNS extension option codes

rip_ns_flag_t

typedef enum rip_ns_flag_e rip_ns_flag_t

DNS message header flags.

rip_ns_header_t

typedef struct rip_ns_header_s rip_ns_header_t

Structure for DNS query header. The order of the fields is machine- and compiler-dependent, depending on the byte/bit order and the layout of bit fields. We use bit fields only in int variables, as this is all ANSI requires.

rip_ns_opcode_t

typedef enum rip_ns_opcode_e rip_ns_opcode_t

DNS opcodes.

rip_ns_rcode_t

typedef enum rip_ns_rcode_e rip_ns_rcode_t

DNS response codes.

rip_ns_type_t

typedef enum rip_ns_type_e rip_ns_type_t

Currently defined type values for DNS resources and queries.

Enumeration Type Documentation

rip_ns_class_e

enum rip_ns_class_e

Values for DNS resource record class field

Enumerator
rip_ns_c_invalid	Cookie.
rip_ns_c_in	Internet.
rip_ns_c_2	unallocated/unsupported.
rip_ns_c_chaos	MIT Chaos-net.
rip_ns_c_hs	MIT Hesiod.
rip_ns_c_none	for prereq. sections in update requests
rip_ns_c_any	Wildcard match.

rip_ns_ext_opt_code_e

enum rip_ns_ext_opt_code_e

EDNS extension option codes

rip_ns_flag_e

enum rip_ns_flag_e

DNS message header flags.

Enumerator
rip_ns_f_qr	Question/Response.
rip_ns_f_opcode	Operation code.
rip_ns_f_aa	Authoritative Answer.
rip_ns_f_tc	Truncation occurred.
rip_ns_f_rd	Recursion Desired.
rip_ns_f_ra	Recursion Available.
rip_ns_f_z	MBZ.
rip_ns_f_ad	Authentic Data (DNSSEC).
rip_ns_f_cd	Checking Disabled (DNSSEC).
rip_ns_f_rcode	Response code.

rip_ns_opcode_e

enum rip_ns_opcode_e

DNS opcodes.

Enumerator
rip_ns_o_query	Standard query.
rip_ns_o_iquery	Inverse query (deprecated/unsupported).
rip_ns_o_status	Name server status query (unsupported).
rip_ns_o_notify	Zone change notification.
rip_ns_o_update	Zone update message.

rip_ns_rcode_e

enum rip_ns_rcode_e

DNS response codes.

Enumerator
rip_ns_r_formerr	Format error.
rip_ns_r_servfail	Server failure.
rip_ns_r_nxdomain	Name error.
rip_ns_r_notimpl	Unimplemented.
rip_ns_r_refused	Operation refused.
rip_ns_r_yxdomain	Name exists
rip_ns_r_yxrrset	RRset exists
rip_ns_r_nxrrset	RRset does not exist
rip_ns_r_notauth	Not authoritative for zone
rip_ns_r_notzone	Zone of record different from zone section
rip_ns_r_rip_tcp_write_err	TCP connection write error, query response not sent
rip_ns_r_rip_tcp_write_close	TCP connection closed for write, query response not sent

rip_ns_type_e

enum rip_ns_type_e

Currently defined type values for DNS resources and queries.

Function Documentation

rip_ns_class_to_str()

const char * rip_ns_class_to_str

(

rip_ns_class_t

class

)

Convert Resource Record enum class to string.

Parameters

class

RR class to get string representation for.

Returns

Returns pointer to string representation of RR class.

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rip_ns_name_ntop()

int rip_ns_name_ntop	(	const unsigned char *	src,
		char *	dst,
		size_t	dstsiz
	)

Converts an uncompressed, encoded domain name to printable ASCII as per RFC1035. Returns the number of bytes written to buffer, or -1 (with errno set). The root is returned as "." All other domains are returned in non absolute form.

Parameters

src	Encoded domain name to convert to printable ASCII.
dst	Destination buffer where to store converted string.
dstsiz	Size of destination buffer.

Returns

On success returns length of string in destination buffer, otherwise returns -1 indicating and error occurred.

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rip_ns_name_pack()

int rip_ns_name_pack	(	const unsigned char *	src,
		unsigned char *	dst,
		int	dstsiz,
		const unsigned char **	dnptrs,
		const unsigned char **	lastdnptr
	)

Packs domain name SRC into DST. Domain name MUST be in "network" format. To convert C string to "network" format use rip_ns_name_pton().

DNPTRS is an array of pointers to previous compressed names. DNPTRS[0] is a pointer to the beginning of the message. The array ends with NULL. LASTDNPTR is a pointer to the end of the array pointed to by 'dnptrs'.

The list of pointers in DNPTRS is updated for labels inserted into the message as we compress the name. If DNPTRS is NULL, we don't try to compress names. If LASTDNPTR is NULL, we don't update the list.

Parameters

src	Domain name in "network" format to pack.
dst	Destination buffer where to pack the domain name.
dstsiz	Length of destination buffer.
dnptrs
lastdnptr

Returns

Returns size of the compressed name, or -1.

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rip_ns_name_pton()

int rip_ns_name_pton	(	const unsigned char *	src,
		unsigned char *	dst,
		size_t	dstsiz
	)

Converts an ASCII string into an encoded domain name as per RFC1035. Enforces label and domain length limits.

Parameters

src	String to encode.
dst	Destination buffer to store encoded string.
dstsiz	Size of destination buffer.

Returns

Returns -1 if it fails, 1 if string was fully qualified, 0 is string was not fully qualified.

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rip_ns_name_put()

int rip_ns_name_put	(	const unsigned char *	src,
		unsigned char *	dst,
		int	dstsiz,
		const unsigned char **	dnptrs,
		const unsigned char **	lastdnptr
	)

Packs domain name SRC into DST. Domain name MUST be a C string. This function converts the C string into "network" format, then packs it into destination buffer.

DNPTRS is an array of pointers to previous compressed names. DNPTRS[0] is a pointer to the beginning of the message. The array ends with NULL. LASTDNPTR is a pointer to the end of the array pointed to by 'dnptrs'.

The list of pointers in DNPTRS is updated for labels inserted into the message as we compress the name. If DNPTRS is NULL, we don't try to compress names. If LASTDNPTR is NULL, we don't update the list.

DNPTRS should be initialized when ready to populate DNS response. It should then be used for all rip_ns_name_put() and rip_ns_name_pack() calls while adding RRs to DNS response.

Parameters

src	Domain name in "network" format to pack.
dst	Destination buffer where to pack the domain name.
dstsiz	Length of destination buffer.
dnptrs
lastdnptr

Returns

Returns size of the compressed name, or -1.

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rip_ns_name_unpack()

int rip_ns_name_unpack	(	const unsigned char *	msg,
		const unsigned char *	eom,
		const unsigned char *	src,
		unsigned char *	dst,
		size_t	dstsiz
	)

Unpack a domain name from a message Resource Record (RR), source may be compressed. Unpacked name will be in "network" format. Use rip_ns_name_ntop() function to convert from "network" to regular C string.

Note

msg passed in MUST be a continuous buffer.

Parameters

msg	Pointer to first byte of DNS message.
eom	Pointer to last byte DNS in message.
src	Pointer to first byte of RR name.
dst	Pointer to buffer where to store the unpacked RR name.
dstsiz	Size of destination buffer.

Returns

Returns -1 if it fails, or consumed octets if it succeeds.

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rip_ns_put16()

void rip_ns_put16 ( unsigned char *  dst, uint16_t  num  )

inline

Pack an unsigned 16 bit integer "num" in host order into buffer "dst" in network order.

Parameters

dst	Destination where to store packed unsigned 16 bit integer.
num	Number to pack.

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rip_ns_rr_class_supported()

bool rip_ns_rr_class_supported

(

uint16_t

query_class

)

Check if DNS resource record class is one of supported types.

Note

Currently only class of IN (Internet) is supported.

Parameters

query_class

DNS resource record type to check.

Returns

Returns true if type is one of supported DNS resource record types, otherwise returns false.

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rip_ns_rr_type_supported()

bool rip_ns_rr_type_supported

(

uint16_t

query_type

)

Check if DNS resource record type is one of supported types.

Parameters

query_type

DNS resource record type to check.

Returns

Returns true if type is one of supported DNS resource record types, otherwise returns false.

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rip_ns_rr_type_to_str()

const char * rip_ns_rr_type_to_str

(

rip_ns_type_t

type

)

Convert Resource Record enum type to string.

Parameters

type	RR type to get string representation for.

Returns

Returns pointer to string representation of RR type.

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rip_rr_name_get()

int rip_rr_name_get	(	const unsigned char *	msg,
		const unsigned char *	eom,
		const unsigned char *	src,
		unsigned char *	dst,
		size_t	dstsiz,
		uint16_t *	query_label_len
	)

Get a domain name from a message Resource Record (RR), source may be compressed. Unpacked name will be in stored in "dst" as to regular C string.

Note

msg passed in MUST be a continuous buffer.

Parameters

msg	Pointer to first byte of DNS message.
eom	Pointer to last byte DNS in message.
src	Pointer to first byte of RR name.
dst	Pointer to buffer where to store the unpacked RR name.
dstsiz	Size of destination buffer.
query_label_len	Pointer where to store length of label extracted and stored in dst.

Returns

Returns -1 if it fails, or consumed octets if it succeeds.

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