sdns.h File Reference

#include <stdint.h>

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Classes
struct	sdns_question
struct	_sdns_opt_rdata
struct	sdns_opt_ttl
struct	_sdns_rr
struct	sdns_header
struct	sdns_message
struct	sdns_rr_A
struct	sdns_rr_AAAA
struct	txt_data
struct	_sdns_rr_TXT
struct	sdns_rr_SOA
struct	sdns_rr_MX
struct	sdns_rr_NS
struct	sdns_rr_PTR
struct	sdns_rr_CNAME
struct	sdns_rr_OPT_EDE
struct	sdns_rr_RRSIG
struct	sdns_rr_SRV
struct	sdns_rr_URI
struct	sdns_rr_NID
struct	sdns_rr_HINFO
struct	sdns_rr_L32
struct	sdns_rr_L64
struct	sdns_rr_LP
struct	sdns_rr_CAA
struct	sdns_context

Macros
#define	TO_OUTPUT(A, B)   do{if (NULL == A) {fprintf(stdout, B);}else{strcpy(A,B);}}while(0);
#define	UDP_PAYLOAD_SIZE   1232
	Default UDP payload size for EDNS0.
#define	DNS_HEADER_LENGTH   12
	Standard DNS Header length.
#define	SDNS_ERROR_MEMORY_ALLOC_FAILED   -1
	memory allocation using malloc() failed
#define	SDNS_ERROR_BUFFER_TOO_SHORT   -2
	DNS packet length is shorter than expected.
#define	SDNS_ERROR_QNAME_IS_NULL   -3
	Qname of the question section can not be null.
#define	SDNS_ERROR_HOSTNAME_TOO_LONG   -4
	Hostname can not be more than 255 characters.
#define	SDNS_ERROR_WRONG_LABEL_SPECIFIED   -5
	Label name is too long or malformed.
#define	SDNS_ERROR_BUFFER_IS_NULL   -6
	passed buffer to the function is NULL
#define	SDNS_ERROR_BUFFER_IS_SMALL   -7
	buffer is shorter than expected
#define	SDNS_ERROR_INVALID_DNS_PACKET   -8
	The packet is not a valid DNS packet.
#define	SDNS_ERROR_MORE_THAN_ONE_QUESTION_FOUND   -9
	Each DNS packet must have exactly one question section.
#define	SDNS_ERROR_RR_NULL   -10
	Resource Record section pointer is NULL.
#define	SDNS_ERROR_ELSIMPLE   -11
	Success code for simple encoding of the name.
#define	SDNS_ERROR_ELCOMPRESSED   -12
	Success code for compressed encoding of the name.
#define	SDNS_ERROR_LABEL_MAX_63   -13
	each part of the name must be <= 63 characters
#define	SDNS_ERROR_ILLEGAL_COMPRESSION   -14
	Compressed label found when it's illegal.
#define	SDNS_ERROR_RR_SECTION_MALFORMED   -15
	Resource Record section is malformed (not enough or wrong data)
#define	SDNS_ERROR_INVALID_HEX_VALUE   -16
	User entered a hex string that is not valid.
#define	SDNS_ERROR_WRONG_INPUT_PARAMETER   -17
	The input parameter is not valid.
#define	SDNS_ERROR_NSID_NOT_FOUND   -18
	There is no NSID in the DNS packet.
#define	SDNS_ERROR_CLIENT_COOKIE_NOT_FOUND   -19
	There is no client cookie in the DNS packet.
#define	SDNS_ERROR_CHARACTER_STRING_TOO_LONG   -20
	Maximum size of character string is 255 character.
#define	SDNS_ERROR_NO_ANSWER_FOUND   -21
	This error shows that the DNS context has no answer section.
#define	SDNS_ERROR_CAN_NOT_READ_SECTION   -22
	For any reason, it's not possible to decode or copy the rdata of the section.
#define	SDNS_ERROR_INVALID_IPv6_FOUND   -23
	The code only accepts IPv6 in a format of ":" separated hex values.
#define	SDNS_ERROR_NO_AUTHORITY_FOUND   -24
	This error shows that the DNS context has no authority section.
#define	SDNS_ERROR_NO_ADDITIONAL_FOUND   -25
	This error shows that the DNS context has no additional section.
#define	SDNS_ERROR_ADDITIONAL_RR_OPT   -26
	Additional section is of type OPT. Use the relevant function to fetch it.
#define	DNS_SECTION_ANSWER   1
	Macro defining the answer section.
#define	DNS_SECTION_AUTHORITY   2
	Macro defining the authority section.
#define	DNS_SECTION_ADDITIONAL   3
	Macro defining the additional section.
#define	DNS_SECTION_QUESTION   4
	Macro defining the question section.
#define	SDNS_QR_MASK   0x8000
#define	SDNS_OPCODE_MASK   0x7800
#define	SDNS_AA_MASK   0x0400
#define	SDNS_TC_MASK   0x0200
#define	SDNS_RD_MASK   0x0100
#define	SDNS_RA_MASK   0x0080
#define	SDNS_Z_MASK   0x0040
#define	SDNS_AD_MASK   0x0020
#define	SDNS_CD_MASK   0x0010
#define	SDNS_RCODE_MASK   0x000F

Typedefs
typedef struct _sdns_opt_rdata	sdns_opt_rdata
	see _sdns_opt_rdata for more info
typedef struct _sdns_rr	sdns_rr
	See _sdns_rr for more info.
typedef struct _sdns_rr_TXT	sdns_rr_TXT

Enumerations
enum	sdns_opcode {   sdns_opcode_Query =0 , sdns_opcode_IQuery =1 , sdns_opcode_Status =2 , sdns_opcode_Notify =4 ,   sdns_opcode_Update =5 , sdns_opcode_DSO =6 }
enum	sdns_rcode {   sdns_rcode_NoError =0 , sdns_rcode_FormErr =1 , sdns_rcode_ServFail =2 , sdns_rcode_NXDomain =3 ,   sdns_rcode_NotImp =4 , sdns_rcode_Refused =5 , sdns_rcode_YXDomain =6 , sdns_rcode_YXRRSet =7 ,   sdns_rcode_NXRRSet =8 , sdns_rcode_NotAuth =9 , sdns_rcode_NotZone =10 , sdns_rcode_DSOTYPENI =11 ,   sdns_rcode_BADVERS =16 , sdns_rcode_BADSIG =16 , sdns_rcode_BADKEY =17 , sdns_rcode_BADTIME =18 ,   sdns_rcode_BADMODE =19 , sdns_rcode_BADNAME =20 , sdns_rcode_BADALG =21 , sdns_rcode_BADTRUNC =22 ,   sdns_rcode_BADCOOKIE =23 , sdns_rcode_Reserved =65535 }
enum	sdns_rr_type {   sdns_rr_type_A =1 , sdns_rr_type_NS =2 , sdns_rr_type_MD =3 , sdns_rr_type_MF =4 ,   sdns_rr_type_CNAME =5 , sdns_rr_type_SOA =6 , sdns_rr_type_MB =7 , sdns_rr_type_MG =8 ,   sdns_rr_type_MR =9 , sdns_rr_type_NULL =10 , sdns_rr_type_WKS =11 , sdns_rr_type_PTR =12 ,   sdns_rr_type_HINFO =13 , sdns_rr_type_MINFO =14 , sdns_rr_type_MX =15 , sdns_rr_type_TXT =16 ,   sdns_rr_type_RP =17 , sdns_rr_type_AFSDB =18 , sdns_rr_type_X25 =19 , sdns_rr_type_ISDN =20 ,   sdns_rr_type_RT =21 , sdns_rr_type_NSAP =22 , sdns_rr_type_NSAP_PTR =23 , sdns_rr_type_SIG =24 ,   sdns_rr_type_KEY =25 , sdns_rr_type_PX =26 , sdns_rr_type_GPOS =27 , sdns_rr_type_AAAA =28 ,   sdns_rr_type_LOC =29 , sdns_rr_type_NXT =30 , sdns_rr_type_EID =31 , sdns_rr_type_NIMLOC =32 ,   sdns_rr_type_SRV =33 , sdns_rr_type_ATMA =34 , sdns_rr_type_NAPTR =35 , sdns_rr_type_KX =36 ,   sdns_rr_type_CERT =37 , sdns_rr_type_A6 =38 , sdns_rr_type_DNAME =39 , sdns_rr_type_SINK =40 ,   sdns_rr_type_OPT =41 , sdns_rr_type_APL =42 , sdns_rr_type_DS =43 , sdns_rr_type_SSHFP =44 ,   sdns_rr_type_IPSECKEY =45 , sdns_rr_type_RRSIG =46 , sdns_rr_type_NSEC =47 , sdns_rr_type_DNSKEY =48 ,   sdns_rr_type_DHCID =49 , sdns_rr_type_NSEC3 =50 , sdns_rr_type_NSEC3PARAM =51 , sdns_rr_type_TLSA =52 ,   sdns_rr_type_SMIMEA =53 , sdns_rr_type_HIP =55 , sdns_rr_type_NINFO =56 , sdns_rr_type_RKEY =57 ,   sdns_rr_type_TALINK =58 , sdns_rr_type_CDS =59 , sdns_rr_type_CDNSKEY =60 , sdns_rr_type_OPENPGPKEY =61 ,   sdns_rr_type_CSYNC =62 , sdns_rr_type_ZONEMD =63 , sdns_rr_type_SVCB =64 , sdns_rr_type_HTTPS =65 ,   sdns_rr_type_SPF =99 , sdns_rr_type_UINFO =100 , sdns_rr_type_UID =101 , sdns_rr_type_GID =102 ,   sdns_rr_type_UNSPEC =103 , sdns_rr_type_NID =104 , sdns_rr_type_L32 =105 , sdns_rr_type_L64 =106 ,   sdns_rr_type_LP =107 , sdns_rr_type_EUI48 =108 , sdns_rr_type_EUI64 =109 , sdns_rr_type_TKEY =249 ,   sdns_rr_type_TSIG =250 , sdns_rr_type_IXFR =251 , sdns_rr_type_AXFR =252 , sdns_rr_type_MAILB =253 ,   sdns_rr_type_MAILA =254 , sdns_rr_type_star =255 , sdns_rr_type_URI =256 , sdns_rr_type_CAA =257 ,   sdns_rr_type_AVC =258 , sdns_rr_type_DOA =259 , sdns_rr_type_AMTRELAY =260 , sdns_rr_type_RESINFO =261 ,   sdns_rr_type_WALLET =262 , sdns_rr_type_TA =32768 , sdns_rr_type_DLV =32769 }
enum	sdns_edns0_option_code {   sdns_edns0_option_code_Reserved0 =0 , sdns_edns0_option_code_LLQ =1 , sdns_edns0_option_code_Update_Lease =2 , sdns_edns0_option_code_NSID =3 ,   sdns_edns0_option_code_Reserved4 =4 , sdns_edns0_option_code_DAU =5 , sdns_edns0_option_code_DHU =6 , sdns_edns0_option_code_N3U =7 ,   sdns_edns0_option_code_edns_client_subnet =8 , sdns_edns0_option_code_EDNS_EXPIRE =9 , sdns_edns0_option_code_COOKIE =10 , sdns_edns0_option_code_edns_tcp_keepalive =11 ,   sdns_edns0_option_code_Padding =12 , sdns_edns0_option_code_CHAIN =13 , sdns_edns0_option_code_edns_key_tag =14 , sdns_edns0_option_code_Extended_DNS_Error =15 ,   sdns_edns0_option_code_EDNS_Client_Tag =16 , sdns_edns0_option_code_EDNS_Server_Tag =17 , sdns_edns0_option_code_Report_Channel =18 , sdns_edns0_option_code_Umbrella_Ident =20292 ,   sdns_edns0_option_code_DeviceID =26946 }
enum	sdns_rr_class { sdns_rr_class_IN =1 , sdns_rr_class_CS =2 , sdns_rr_class_CH =3 , sdns_rr_class_HS =4 }
enum	sdns_q_class {   sdns_q_class_IN =1 , sdns_q_class_CS =2 , sdns_q_class_CH =3 , sdns_q_class_HS =4 ,   sdns_q_class_STAR =255 }
enum	sdns_ede_code {   sdns_ede_code_Other_Error =0 , sdns_ede_code_Unsupported_DNSKEY_Algorithm =1 , sdns_ede_code_Unsupported_DS_Digest_Type =2 , sdns_ede_code_Stale_Answer =3 ,   sdns_ede_code_Forged_Answer =4 , sdns_ede_code_DNSSEC_Indeterminate =5 , sdns_ede_code_DNSSEC_Bogus =6 , sdns_ede_code_Signature_Expired =7 ,   sdns_ede_code_Signature_Not_Yet_Valid =8 , sdns_ede_code_DNSKEY_Missing =9 , sdns_ede_code_RRSIGs_Missing =10 , sdns_ede_code_No_Zone_Key_Bit_Set =11 ,   sdns_ede_code_NSEC_Missing =12 , sdns_ede_code_Cached_Error =13 , sdns_ede_code_Not_Ready =14 , sdns_ede_code_Blocked =15 ,   sdns_ede_code_Censored =16 , sdns_ede_code_Filtered =17 , sdns_ede_code_Prohibited =18 , sdns_ede_code_Stale_NXDomain_Answer =19 ,   sdns_ede_code_Not_Authoritative =20 , sdns_ede_code_Not_Supported =21 , sdns_ede_code_No_Reachable_Authority =22 , sdns_ede_code_Network_Error =23 ,   sdns_ede_code_Invalid_Data =24 , sdns_ede_code_Signature_Expired_before_Valid =25 , sdns_ede_code_Too_Early =26 , sdns_ede_code_Unsupported_NSEC3_Iterations_Value =27 ,   sdns_ede_code_Unable_to_conform_to_policy =28 , sdns_ede_code_Synthesized =29 }

Functions
int	sdns_make_query (sdns_context *ctx, sdns_rr_type qtype, sdns_q_class cls, char *qname, int enable_edns0)
	Creates a DNS question query.
int	sdns_to_wire (sdns_context *ctx)
	Coverts a DNS context to binary format.
int	sdns_from_wire (sdns_context *ctx)
	Converts the raw data received from socket (bytes) to a DNS packet.
void	sdns_error_string (int err, char **err_buff)
	Coverts error codes to a string.
sdns_context *	sdns_init_context (void)
	Initialize and create a new DNS context.
void	sdns_free_context (sdns_context *ctx)
	Frees the context allocated by sdns_init_context().
int	sdns_add_answer_section (sdns_context *ctx, sdns_rr *rr)
	Creates an answer section for the DNS packet.
int	sdns_add_authority_section (sdns_context *ctx, sdns_rr *rr)
	Adds a new RR to the authority section of the DNS packet.
int	sdns_add_additional_section (sdns_context *ctx, sdns_rr *rr)
	Adds a new RR to the additional section of the DNS packet.
int	check_if_qtype_is_valid (uint16_t qtype)
	This function checks if the given qtype code is valid or not.
int	check_if_rrtype_is_valid (uint16_t qtype)
	This function checks if the given RR type is valid or not.
int	check_if_qclass_is_valid (uint16_t qclass)
	This function checks if the given Question class is valid or not.
int	check_if_rrclass_is_valid (uint16_t qclass)
	This function checks if the given RR class is valid or not.
sdns_message *	sdns_init_message (void)
	Initialize a DNS message structure (sdns_message).
sdns_rr *	sdns_init_rr (char *name, uint16_t type, uint16_t class, uint32_t ttl, uint16_t rdlength, uint8_t decoded, void *rdata)
	Initialize an RR data structure.
int	sdns_create_edns_option (uint16_t, uint16_t, char *, sdns_opt_rdata **)
int	sdns_add_edns (sdns_context *ctx, sdns_opt_rdata *opt)
sdns_opt_rdata *	sdns_create_edns0_ede (uint16_t info_code, char *extra_text, uint16_t extra_text_len)
	Creates EDNS0 extended DNS error option.
sdns_opt_rdata *	sdns_create_edns0_nsid (char *nsid, uint16_t nsid_len)
int	sdns_ends0_option_code_to_text (sdns_edns0_option_code oc, char *buffer)
	Copies the text description of the EDNS0 option code to the buffer.
void *	sdns_copy_rr_section (sdns_context *, sdns_rr *)
void *	sdns_decode_rr_section (sdns_context *, sdns_rr *)
sdns_rr_A *	sdns_decode_rr_A (sdns_context *, sdns_rr *)
sdns_rr_AAAA *	sdns_decode_rr_AAAA (sdns_context *, sdns_rr *)
sdns_rr_TXT *	sdns_decode_rr_TXT (sdns_context *, sdns_rr *)
sdns_rr_SOA *	sdns_decode_rr_SOA (sdns_context *, sdns_rr *)
sdns_rr_MX *	sdns_decode_rr_MX (sdns_context *, sdns_rr *)
sdns_rr_NS *	sdns_decode_rr_NS (sdns_context *ctx, sdns_rr *rr)
sdns_rr_PTR *	sdns_decode_rr_PTR (sdns_context *ctx, sdns_rr *rr)
sdns_rr_CNAME *	sdns_decode_rr_CNAME (sdns_context *ctx, sdns_rr *rr)
sdns_rr_RRSIG *	sdns_decode_rr_RRSIG (sdns_context *ctx, sdns_rr *rr)
sdns_rr_SRV *	sdns_decode_rr_SRV (sdns_context *ctx, sdns_rr *rr)
sdns_rr_HINFO *	sdns_decode_rr_HINFO (sdns_context *ctx, sdns_rr *rr)
sdns_rr_URI *	sdns_decode_rr_URI (sdns_context *ctx, sdns_rr *rr)
sdns_rr_NID *	sdns_decode_rr_NID (sdns_context *ctx, sdns_rr *rr)
sdns_rr_L32 *	sdns_decode_rr_L32 (sdns_context *ctx, sdns_rr *rr)
sdns_rr_L64 *	sdns_decode_rr_L64 (sdns_context *ctx, sdns_rr *rr)
sdns_rr_LP *	sdns_decode_rr_LP (sdns_context *ctx, sdns_rr *rr)
sdns_rr_CAA *	sdns_decode_rr_CAA (sdns_context *ctx, sdns_rr *rr)
sdns_opt_rdata *	sdns_decode_rr_OPT (sdns_context *ctx, sdns_rr *rr)
sdns_rr_A *	sdns_init_rr_A (uint32_t ipaddress)
	Initialize a structure of sdns_rr_A.
sdns_rr_AAAA *	sdns_init_rr_AAAA (char *aaaa)
	Initialize a structure of sdns_rr_AAAA.
sdns_rr_TXT *	sdns_init_rr_TXT (char *data, uint16_t data_len)
	Initialize a structure of sdns_rr_TXT.
sdns_rr_SRV *	sdns_init_rr_SRV (uint16_t Priority, uint16_t Weight, uint16_t Port, char *target)
	Initialize a structure of sdns_rr_SRV.
sdns_rr_MX *	sdns_init_rr_MX (uint16_t preference, char *exchange)
	Initialize a structure of sdns_rr_MX.
sdns_rr_NS *	sdns_init_rr_NS (char *nsdname)
	Initialize a structure of sdns_rr_NS.
sdns_rr_PTR *	sdns_init_rr_PTR (char *ptrdname)
	Initialize a structure of sdns_rr_PTR.
sdns_rr_CNAME *	sdns_init_rr_CNAME (char *cname)
	Initialize a structure of sdns_rr_CNAME.
sdns_rr_NID *	sdns_init_rr_NID (uint16_t preference, char *nodid)
	Initialize a structure of sdns_rr_NID.
sdns_rr_L32 *	sdns_init_rr_L32 (uint16_t preference, uint32_t locator32)
	Initialize a structure of sdns_rr_L32.
sdns_rr_L64 *	sdns_init_rr_L64 (uint16_t preference, char *locator64)
	Initialize a structure of sdns_rr_L64.
sdns_rr_LP *	sdns_init_rr_LP (uint16_t preference, char *fqdn)
	Initialize a structure of sdns_rr_LP.
sdns_rr_CAA *	sdns_init_rr_CAA (uint8_t flag, char *tag, uint8_t tag_len, char *value, uint16_t value_len)
	Initialize a structure of sdns_rr_CAA.
void	sdns_free_opt_rdata (sdns_opt_rdata *opt)
sdns_opt_rdata *	sdns_init_opt_rdata (void)
sdns_rr_SRV *	sdns_init_SRV (uint16_t, uint16_t, uint16_t, char *)
sdns_rr_URI *	sdns_init_rr_URI (uint16_t, uint16_t, char *, uint16_t)
sdns_rr_RRSIG *	sdns_init_rr_RRSIG (uint16_t, uint8_t, uint8_t, uint32_t, uint32_t, uint32_t, uint8_t, char *, char *, uint16_t)
sdns_rr_HINFO *	sdns_init_rr_HINFO (uint8_t cpu_len, char *cpu, uint8_t os_len, char *os)
sdns_rr_SOA *	sdns_init_rr_SOA (char *mname, char *rname, uint32_t expire, uint32_t minimum, uint32_t refresh, uint32_t retry, uint32_t serial)
void	sdns_free_rr_A (sdns_rr_A *a)
	Free the memory of the structure of type sdns_rr_A.
void	sdns_free_rr_MX (sdns_rr_MX *mx)
	Free the memory of the structure of type sdns_rr_MX.
void	sdns_free_rr_TXT (sdns_rr_TXT *txt)
	Free the memory of the structure of type sdns_rr_TXT.
void	sdns_free_rr_AAAA (sdns_rr_AAAA *aaaa)
	Free the memory of the structure of type sdns_rr_AAAA.
void	sdns_free_rr_SOA (sdns_rr_SOA *soa)
	Free the memory of the structure of type sdns_rr_SOA.
void	sdns_free_rr_NS (sdns_rr_NS *ns)
	Free the memory of the structure of type sdns_rr_NS.
void	sdns_free_rr_PTR (sdns_rr_PTR *ptr)
	Free the memory of the structure of type sdns_rr_PTR.
void	sdns_free_rr_CNAME (sdns_rr_CNAME *cname)
	Free the memory of the structure of type sdns_rr_CNAME.
void	sdns_free_rr_RRSIG (sdns_rr_RRSIG *rrsig)
	Free the memory of the structure of type sdns_rr_RRSIG.
void	sdns_free_rr_SRV (sdns_rr_SRV *srv)
	Free the memory of the structure of type sdns_rr_SRV.
void	sdns_free_rr_HINFO (sdns_rr_HINFO *hinfo)
	Free the memory of the structure of type sdns_rr_HINFO.
void	sdns_free_rr_URI (sdns_rr_URI *uri)
	Free the memory of the structure of type sdns_rr_URI.
void	sdns_free_rr_NID (sdns_rr_NID *nid)
	Free the memory of the structure of type sdns_rr_NID.
void	sdns_free_rr_L32 (sdns_rr_L32 *l32)
	Free the memory of the structure of type sdns_rr_L32.
void	sdns_free_rr_L64 (sdns_rr_L64 *l64)
	Free the memory of the structure of type sdns_rr_L64.
void	sdns_free_rr_LP (sdns_rr_LP *lp)
	Free the memory of the structure of type sdns_rr_LP.
void	sdns_free_rr_CAA (sdns_rr_CAA *caa)
	Free the memory of the structure of type sdns_rr_CAA.
sdns_opt_rdata *	sdns_create_edns0_cookie (char *client_cookie, char *server_cookie, uint8_t server_cookie_len)
	Creates and adds a cookie in the DNS packet.
void	sdns_rr_type_to_string (uint16_t t, char *buff)
	Gets the string representation of the TYPE tp in to buffer
void	sdns_class_to_string (uint16_t cls, char *buff)
	Gets the string representation of the CLASS cls in to buffer
int	sdns_convert_type_to_int (char *type)
	Converts text type to its numerical value.
int	sdns_convert_class_to_int (char *cls)
	Converts text class to its numerical value.
void	sdns_free_section (sdns_rr *rr)
	free a DNS resource record no matter of the type

Macro Definition Documentation

SDNS_ERROR_ILLEGAL_COMPRESSION

#define SDNS_ERROR_ILLEGAL_COMPRESSION   -14

Compressed label found when it's illegal.

In some cases like RRSIG, the name can not be compressed (e.g., signer's name in RRSIG). So if we found a compressed name in those sections, we return this error

Typedef Documentation

sdns_opt_rdata

typedef struct _sdns_opt_rdata sdns_opt_rdata

see _sdns_opt_rdata for more info

See _sdns_opt_rdata structure for detail.

sdns_rr

typedef struct _sdns_rr sdns_rr

See _sdns_rr for more info.

See _sdns_rr for more information

sdns_rr_TXT

typedef struct _sdns_rr_TXT sdns_rr_TXT

check the definition of _sdns_rr_TXT.

Enumeration Type Documentation

sdns_ede_code

enum sdns_ede_code

List of known value for Extended DNS Errors (EDE). The full list is available in RFC 8914

Enumerator
sdns_ede_code_Other_Error	Other.
sdns_ede_code_Unsupported_DNSKEY_Algorithm	Unsupported DNSKEY Algorithm.
sdns_ede_code_Unsupported_DS_Digest_Type	Unsupported DS Digest Type.
sdns_ede_code_Stale_Answer	Stale Answer.
sdns_ede_code_Forged_Answer	For policy reasons (legal obligation or malware filtering, for instance), an answer was forged.
sdns_ede_code_DNSSEC_Indeterminate	DNSSEC Indeterminate.
sdns_ede_code_DNSSEC_Bogus	The resolver attempted to perform DNSSEC validation, but validation ended in the Bogus state.
sdns_ede_code_Signature_Expired	Signature Expired.
sdns_ede_code_Signature_Not_Yet_Valid	Signature Not Yet Valid.
sdns_ede_code_DNSKEY_Missing	A DS record existed at a parent, but no supported matching DNSKEY record could be found for the child.
sdns_ede_code_RRSIGs_Missing	RRSIGs Missing.
sdns_ede_code_No_Zone_Key_Bit_Set	The resolver attempted to perform DNSSEC validation, but no Zone Key Bit was set in a DNSKEY.
sdns_ede_code_NSEC_Missing	NSEC Missing.
sdns_ede_code_Cached_Error	Cached Error.
sdns_ede_code_Not_Ready	The server is unable to answer the query, as it was not fully functional when the query was received.
sdns_ede_code_Blocked	Blocked.
sdns_ede_code_Censored	Censored.
sdns_ede_code_Filtered	Filtered.
sdns_ede_code_Prohibited	Prohibited.
sdns_ede_code_Stale_NXDomain_Answer	Stale NXDOMAIN Answer.
sdns_ede_code_Not_Authoritative	Not Authoritative.
sdns_ede_code_Not_Supported	Not Supported.
sdns_ede_code_No_Reachable_Authority	No Reachable Authority.
sdns_ede_code_Network_Error	Network Error.
sdns_ede_code_Invalid_Data	Invalid Data.
sdns_ede_code_Signature_Expired_before_Valid	Signature Expired before Valid.
sdns_ede_code_Too_Early	Too Early
sdns_ede_code_Unsupported_NSEC3_Iterations_Value	Unsupported NSEC3 Iterations Value.
sdns_ede_code_Unable_to_conform_to_policy	Unable to conform to policy.
sdns_ede_code_Synthesized	Synthesized.

sdns_edns0_option_code

enum sdns_edns0_option_code

Possible valid values for the option code of EDNS0 https://www.iana.org/assignments/dns-parameters/dns-parameters.xhtml#dns-parameters-11

Enumerator
sdns_edns0_option_code_Reserved0	Reserved RFC6891.
sdns_edns0_option_code_LLQ	LLQ RFC8764.
sdns_edns0_option_code_Update_Lease	Update Lease.
sdns_edns0_option_code_NSID	NSID RFC5001.
sdns_edns0_option_code_Reserved4	Reserved.
sdns_edns0_option_code_DAU	DAU RFC6975.
sdns_edns0_option_code_DHU	DHU RFC6975.
sdns_edns0_option_code_N3U	N3U RFC6975.
sdns_edns0_option_code_edns_client_subnet	edns-client-subnet RFC7871
sdns_edns0_option_code_EDNS_EXPIRE	EDNS EXPIRE RFC7314.
sdns_edns0_option_code_COOKIE	COOKIE RFC7873.
sdns_edns0_option_code_edns_tcp_keepalive	edns-tcp-keepalive RFC7828
sdns_edns0_option_code_Padding	Padding RFC7830.
sdns_edns0_option_code_CHAIN	CHAIN RFC7901.
sdns_edns0_option_code_edns_key_tag	edns-key-tag RFC8145
sdns_edns0_option_code_Extended_DNS_Error	Extended DNS Error RFC8914.
sdns_edns0_option_code_EDNS_Client_Tag	EDNS-Client-Tag.
sdns_edns0_option_code_EDNS_Server_Tag	EDNS-Server-Tag.
sdns_edns0_option_code_Report_Channel	Report-Channel RFC9567.
sdns_edns0_option_code_Umbrella_Ident	Umbrella Ident.
sdns_edns0_option_code_DeviceID	DeviceID.

sdns_opcode

enum sdns_opcode

The list of opcodes can be found at: http://www.iana.org/assignments/dns-parameters/dns-parameters.xhtml#dns-parameters-5

Enumerator
sdns_opcode_Query	RFC1035.
sdns_opcode_IQuery	RFC1035.
sdns_opcode_Status	RFC1035.
sdns_opcode_Notify	RFC1996.
sdns_opcode_Update	RFC2136.
sdns_opcode_DSO	RFC8490.

sdns_q_class

enum sdns_q_class

Possible values for the CLASS field of a question section

Enumerator
sdns_q_class_IN	RFC1035 - the Internet.
sdns_q_class_CS	RFC1035 - the CSNET.
sdns_q_class_CH	RFC1035 - the CHAOS class.
sdns_q_class_HS	RFC1035 - Hesiod.
sdns_q_class_STAR	RFC1035 - any class.

sdns_rcode

enum sdns_rcode

The list of standard error codes for DNS can be found at: http://www.iana.org/assignments/dns-parameters/dns-parameters.xhtml#dns-parameters-6

Enumerator
sdns_rcode_NoError	RFC1035.
sdns_rcode_FormErr	RFC1035.
sdns_rcode_ServFail	RFC1035.
sdns_rcode_NXDomain	RFC1035.
sdns_rcode_NotImp	RFC1035.
sdns_rcode_Refused	RFC1035.
sdns_rcode_YXDomain	RFC2136.
sdns_rcode_YXRRSet	RFC2136.
sdns_rcode_NXRRSet	RFC2136.
sdns_rcode_NotAuth	RFC2136, RFC8945.
sdns_rcode_NotZone	RFC2136.
sdns_rcode_DSOTYPENI	RFC8490.
sdns_rcode_BADVERS	Bad OPT Version RFC6891.
sdns_rcode_BADSIG	TSIG Signature Failure RFC8945.
sdns_rcode_BADKEY	Key not recognized RFC8945.
sdns_rcode_BADTIME	Signature out of time window RFC8945.
sdns_rcode_BADMODE	Bad TKEY Mode RFC2930.
sdns_rcode_BADNAME	Duplicate key name RFC2930.
sdns_rcode_BADALG	Algorithm not supported RFC2930.
sdns_rcode_BADTRUNC	Bad Truncation RFC8945.
sdns_rcode_BADCOOKIE	Bad/missing Server Cookie RFC7873.
sdns_rcode_Reserved	Reserved, can be allocated by Standards Action RFC6895.

sdns_rr_class

enum sdns_rr_class

Possible values for the CLASS field of a Resource Record

Enumerator
sdns_rr_class_IN	RFC1035 - the Internet.
sdns_rr_class_CS	RFC1035 - the CSNET.
sdns_rr_class_CH	RFC1035 - the CHAOS class.
sdns_rr_class_HS	RFC1035 - Hesiod.

sdns_rr_type

enum sdns_rr_type

Here is the list of possible RR types reitrieved from: https://www.iana.org/assignments/dns-parameters/dns-parameters.xhtml#dns-parameters-4

Enumerator
sdns_rr_type_A	RFC1035 - A record.
sdns_rr_type_NS	RFC1035 - NS record.
sdns_rr_type_MD	RFC1035 - mail destination record.
sdns_rr_type_MF	RFC1035 - mail forwarder record.
sdns_rr_type_CNAME	RFC1035 - canonical name.
sdns_rr_type_SOA	RFC1035 - start of a zone of authority.
sdns_rr_type_MB	RFC1035 - mailbox domain name.
sdns_rr_type_MG	RFC1035 - mail group member.
sdns_rr_type_MR	RFC1035 - mail rename domain name.
sdns_rr_type_NULL	RFC1035 - a null RR.
sdns_rr_type_WKS	RFC1035 - a well known service description.
sdns_rr_type_PTR	RFC1035 - a domain name pointer.
sdns_rr_type_HINFO	RFC1035 - host information.
sdns_rr_type_MINFO	RFC1035 - mailbox or mail list information.
sdns_rr_type_MX	RFC1035 - mail exchange.
sdns_rr_type_TXT	RFC1035 - text strings.
sdns_rr_type_RP	for Responsible Person RFC1183
sdns_rr_type_AFSDB	for AFS Data Base location RFC1183, RFC5864
sdns_rr_type_X25	for X.25 PSDN address RFC1183
sdns_rr_type_ISDN	for ISDN address RFC1183
sdns_rr_type_RT	for Route Through RFC1183
sdns_rr_type_NSAP	for NSAP address, NSAP style A record (deprecated)
sdns_rr_type_NSAP_PTR	for domain name pointer, NSAP style
sdns_rr_type_SIG	for security signature RFC2536, RFC2931, RFC3110, RFC4034
sdns_rr_type_KEY	for security key RFC2536, RFC2539, RFC3110, RFC4034
sdns_rr_type_PX	X.400 mail mapping information FC2163.
sdns_rr_type_GPOS	Geographical Position RFC1712.
sdns_rr_type_AAAA	RFC3596 - AAAA record.
sdns_rr_type_LOC	Location Information RFC1876.
sdns_rr_type_NXT	Next Domain (OBSOLETE) RFC2535, RFC3755.
sdns_rr_type_EID	Endpoint Identifier.
sdns_rr_type_NIMLOC	Nimrod Locator.
sdns_rr_type_SRV	Server Selection.
sdns_rr_type_ATMA	ATM Address.
sdns_rr_type_NAPTR	Naming Authority Pointer.
sdns_rr_type_KX	Key Exchanger.
sdns_rr_type_CERT	CERT.
sdns_rr_type_A6	A6 (OBSOLETE - use AAAA)
sdns_rr_type_DNAME	DNAME.
sdns_rr_type_SINK	SINK.
sdns_rr_type_OPT	RFC6891 - option RR for ends.
sdns_rr_type_APL	APL.
sdns_rr_type_DS	Delegation Signer RFC4034.
sdns_rr_type_SSHFP	SSH Key Fingerprint RFC4255.
sdns_rr_type_IPSECKEY	IPSECKEY RFC4025.
sdns_rr_type_RRSIG	RRSIG RFC4034.
sdns_rr_type_NSEC	NSEC RFC4034, RFC9077.
sdns_rr_type_DNSKEY	DNSKEY RFC4034.
sdns_rr_type_DHCID	DHCID RFC4701.
sdns_rr_type_NSEC3	NSEC3 RFC5155, RFC9077.
sdns_rr_type_NSEC3PARAM	NSEC3PARAM [RFC5155.
sdns_rr_type_TLSA	TLSA [RFC6698.
sdns_rr_type_SMIMEA	S/MIME cert association RFC8162.
sdns_rr_type_HIP	Host Identity Protocol RFC8005.
sdns_rr_type_NINFO	NINFO.
sdns_rr_type_RKEY	RKEY.
sdns_rr_type_TALINK	Trust Anchor LINK.
sdns_rr_type_CDS	Child DS.
sdns_rr_type_CDNSKEY	DNSKEY(s) the Child wants reflected in DS RFC7344.
sdns_rr_type_OPENPGPKEY	OpenPGP Key RFC7929.
sdns_rr_type_CSYNC	Child-To-Parent Synchronization RFC7477.
sdns_rr_type_ZONEMD	Message Digest Over Zone Data RFC8976.
sdns_rr_type_SVCB	General-purpose service binding RFC9460.
sdns_rr_type_HTTPS	SVCB-compatible type for use with HTTP RFC9460.
sdns_rr_type_SPF	RFC7208.
sdns_rr_type_UINFO	IANA-Reserved.
sdns_rr_type_UID	IANA-Reserved.
sdns_rr_type_GID	IANA-Reserved.
sdns_rr_type_UNSPEC	IANA-Reserved.
sdns_rr_type_NID	RFC6742.
sdns_rr_type_L32	RFC6742.
sdns_rr_type_L64	RFC6742.
sdns_rr_type_LP	RFC6742.
sdns_rr_type_EUI48	an EUI-48 address RFC7043
sdns_rr_type_EUI64	an EUI-64 address RFC7043
sdns_rr_type_TKEY	Transaction Key RFC2930.
sdns_rr_type_TSIG	Transaction Signature RFC8945.
sdns_rr_type_IXFR	incremental transfer RFC1995
sdns_rr_type_AXFR	RFC1035 - request for transfer of entire zone.
sdns_rr_type_MAILB	RFC1035 - request for mailbox related records.
sdns_rr_type_MAILA	RFC1035 - request for mail agent RRs.
sdns_rr_type_star	RFC1035 - request for all records.
sdns_rr_type_URI	URI RFC7553.
sdns_rr_type_CAA	Certification Authority Restriction [RFC8659].
sdns_rr_type_AVC	Application Visibility and Control.
sdns_rr_type_DOA	Digital Object Architecture.
sdns_rr_type_AMTRELAY	Automatic Multicast Tunneling Relay [RFC8777].
sdns_rr_type_RESINFO	Resolver Information as Key/Value Pairs.
sdns_rr_type_WALLET	Public wallet address.
sdns_rr_type_TA	DNSSEC Trust Authorities.
sdns_rr_type_DLV	DNSSEC Lookaside Validation (OBSOLETE)

Function Documentation

check_if_qclass_is_valid()

int check_if_qclass_is_valid

(

uint16_t

qclass

)

This function checks if the given Question class is valid or not.

Parameters

qclass

input Resource record class

Returns

0 if the given value is valid else 1

check_if_qtype_is_valid()

int check_if_qtype_is_valid

(

uint16_t

qtype

)

This function checks if the given qtype code is valid or not.

Parameters

qtype

16-bit unsigned integer

Returns

1 if given qtype is valid on 0 otherwise

check_if_rrclass_is_valid()

int check_if_rrclass_is_valid

(

uint16_t

qclass

)

This function checks if the given RR class is valid or not.

Parameters

qclass

input Resource record class

Returns

0 if the given value is valid else 1

check_if_rrtype_is_valid()

int check_if_rrtype_is_valid

(

uint16_t

qtype

)

This function checks if the given RR type is valid or not.

Parameters

qtype

input Resource record type

Returns

0 if the given value is valid else 1

sdns_add_additional_section()

int sdns_add_additional_section	(	sdns_context *	ctx,
		sdns_rr *	rr
	)

Adds a new RR to the additional section of the DNS packet.

Parameters

ctx	A pointer to DNS context created by sdns_init_context()
rr	A pointer to the RR we want to add.

Returns

0 on success and other values on failure (call sdns_error_string() to get the error string)

This function is exactly the same as sdns_add_answer_section() but adds the new record to additional section of the DNS packet instead of the answer section.

For more info, check the provided example in sdns_add_answer_section() function.

NOTE: We don't use this function to add EDNS0 options. Instead, we use sdns_add_edns() function.

sdns_add_answer_section()

int sdns_add_answer_section	(	sdns_context *	ctx,
		sdns_rr *	rr
	)

Creates an answer section for the DNS packet.

Parameters

ctx	A pointer to the DNS context created by sdns_init_context().
rr	A pointer to the sdns_rr structure we want to add.

Returns

0 on success and other values on failure (call sdns_error_string() to get the error string)

// let's create a new context
sdns_context * dns_ctx = sdns_init_context();
if (NULL == dns_ctx){
    fprintf(stderr, "Can not initialize the DNS context...\n");
    return 1;
}
// let's make a query (google.com. IN TXT with EDNS0 enabled)
int res = sdns_make_query(dns_ctx, sdns_rr_type_TXT, sdns_q_class_IN, strdup("google.com"), 1);
if (res != 0){
    // handle errors and return
} 
// let's add an answer section for TXT record
// first we have to create a TXT structure using sdns_init_rr_TXT() function.
sdns_rr_TXT * txt = sdns_init_rr_TXT(strdup("This_is_a_txt_record"), 16);
// then we create a new section by calling sdns_init_rr() function.
sdns_rr * rr = sdns_init_rr(strdup("google.com"), sdns_rr_type_TXT, sdns_rr_class_IN, 86400, 0, 1, (void*)txt);
if (rr == NULL){
    // handle errors and exit
}
// finally, we add the newly created section to our context.
res = sdns_add_answer_section(dns_ctx, rr);
if (res != 0){
    // handle errors and exit
}
// let's print the final packet to see if works.
sdns_neat_print_dns(dns_ct void sdns_free_context(sdns_context *ctx)                                                           
sdns_free_context(dns_ctx);

sdns_add_authority_section()

int sdns_add_authority_section	(	sdns_context *	ctx,
		sdns_rr *	rr
	)

Adds a new RR to the authority section of the DNS packet.

Parameters

ctx	A pointer to DNS context created by sdns_init_context()
rr	A pointer to the RR we want to add.

Returns

0 on success and other values on failure (call sdns_error_string() to get the error string)

This function is exactly the same as sdns_add_answer_section() but adds the new record to authority section of the DNS packet instead of the answer section.

For more info, check the provided example in sdns_add_answer_section() function.

sdns_class_to_string()

void sdns_class_to_string	(	uint16_t	cls,
		char *	buff
	)

Gets the string representation of the CLASS cls in to buffer

Parameters

cls	A 16bit integer, one of the possible values of sdns_rr_class or sdns_q_class
buff	A pointer to the user-provided buffer

The buff must be long enough to cover all classes.

Currently, a buffer of length 20 is enough.

sdns_convert_class_to_int()

int sdns_convert_class_to_int

(

char *

cls

)

Converts text class to its numerical value.

Parameters

cls	a pointer to the class string (e.g., "IN" or "ch")

Returns

A positive integer on success showing the DNS class or negative value in case of unknown class

sdns_convert_type_to_int()

int sdns_convert_type_to_int

(

char *

type

)

Converts text type to its numerical value.

Parameters

type	a pointer to the type string (e.g., "AAAA")

Returns

A positive integer on success showing the type or negative value in case of unknown type

sdns_create_edns0_cookie()

sdns_opt_rdata * sdns_create_edns0_cookie	(	char *	client_cookie,
		char *	server_cookie,
		uint8_t	server_cookie_len
	)

Creates and adds a cookie in the DNS packet.

Parameters

client_cookie	This parameter can not be NULL. It must be provided and the length is exactly 8 bytes.
server_cookie	this is an optional parameter which can be NULL or a pointer to a memory which stores the cookie
server_cookie_len	The length of the server cookie which can be between 8 and 32 (both valued included).

the caller can free() the memory of 'client_cookie' and 'server_cookie' params after calling the method. The library creates an internal copy of the data.

Returns

a pointer to an instance of type sdns_opt_rdata on success, NULL on failure.

On success, you can add the returned structure to the DNS packet by calling sdns_create_edns_option() function.

sdns_create_edns0_ede()

sdns_opt_rdata * sdns_create_edns0_ede	(	uint16_t	info_code,
		char *	extra_text,
		uint16_t	extra_text_len
	)

Creates EDNS0 extended DNS error option.

Parameters

info_code	One of the possible values of sdns_ede_code
extra_text	A text description of the error or whatever you want to send
extra_text_len	the length of the extra_text filed (as it's not necessarily nul-terminated)

This function creates a new copy of 'extra_text' field. So the caller is responsible to free the memory of 'extra_text' if it's a heap-allocated memory.

Returns

returns a pointer to a sdns_opt_rdata structure on success, NULL on fail.

sdns_ends0_option_code_to_text()

int sdns_ends0_option_code_to_text	(	sdns_edns0_option_code	oc,
		char *	buffer
	)

Copies the text description of the EDNS0 option code to the buffer.

Parameters

oc	the numerical value of the edns0 option code, one of the possible values of sdns_edns0_option_code
buffer	The user provided buffer to receive the string.

The user provided buffer must be large enough to cover the longest string. You can pass a buffer of length 100 to make sure it goes well.

Returns

0 on success, other values on failure.

if the return value is 0, it means the given 'oc' value is a valid EDNS option code. If the return value is 1, it means the given 'oc' value is not a valid EDNS option code.

This means you can also use this function as a validator to check of 'oc' is valid or not.

sdns_error_string()

void sdns_error_string	(	int	err,
		char **	err_buff
	)

Coverts error codes to a string.

Parameters

err	the error code you received from one of the functions or any DNS defined error.
err_buff	A double pointer to the buffer to receive the string. if it's NULL, we will allocate memory.

The err_buff parameter must be large enough to cover all possible error codes. Currently, no error string is larger than 256. Hence, 256 bytes of buffer is large enough and safe.

check the source code example in sdns_make_query() for more information.

sdns_free_context()

void sdns_free_context

(

sdns_context *

ctx

)

Frees the context allocated by sdns_init_context().

Parameters

ctx	A pointer to the context.

To prevent memory leak, you must free the context all the time.

This function will call all other sdns_free_*() functions recursively to free the whole memory.

sdns_free_rr_A()

void sdns_free_rr_A

(

sdns_rr_A *

a

)

Free the memory of the structure of type sdns_rr_A.

Parameters

a	A pointer to the structure

sdns_free_rr_AAAA()

void sdns_free_rr_AAAA

(

sdns_rr_AAAA *

aaaa

)

Free the memory of the structure of type sdns_rr_AAAA.

Parameters

aaaa	A pointer to the structure

sdns_free_rr_CAA()

void sdns_free_rr_CAA

(

sdns_rr_CAA *

caa

)

Free the memory of the structure of type sdns_rr_CAA.

Parameters

caa	A pointer to the structure

sdns_free_rr_CNAME()

void sdns_free_rr_CNAME

(

sdns_rr_CNAME *

cname

)

Free the memory of the structure of type sdns_rr_CNAME.

Parameters

cname

A pointer to the structure

sdns_free_rr_HINFO()

void sdns_free_rr_HINFO

(

sdns_rr_HINFO *

hinfo

)

Free the memory of the structure of type sdns_rr_HINFO.

Parameters

hinfo

A pointer to the structure

sdns_free_rr_L32()

void sdns_free_rr_L32

(

sdns_rr_L32 *

l32

)

Free the memory of the structure of type sdns_rr_L32.

Parameters

l32	A pointer to the structure

sdns_free_rr_L64()

void sdns_free_rr_L64

(

sdns_rr_L64 *

l64

)

Free the memory of the structure of type sdns_rr_L64.

Parameters

l64	A pointer to the structure

sdns_free_rr_LP()

void sdns_free_rr_LP

(

sdns_rr_LP *

lp

)

Free the memory of the structure of type sdns_rr_LP.

Parameters

lp	A pointer to the structure

sdns_free_rr_MX()

void sdns_free_rr_MX

(

sdns_rr_MX *

mx

)

Free the memory of the structure of type sdns_rr_MX.

Parameters

mx	A pointer to the structure

sdns_free_rr_NID()

void sdns_free_rr_NID

(

sdns_rr_NID *

nid

)

Free the memory of the structure of type sdns_rr_NID.

Parameters

nid	A pointer to the structure

sdns_free_rr_NS()

void sdns_free_rr_NS

(

sdns_rr_NS *

ns

)

Free the memory of the structure of type sdns_rr_NS.

Parameters

ns	A pointer to the structure

sdns_free_rr_PTR()

void sdns_free_rr_PTR

(

sdns_rr_PTR *

ptr

)

Free the memory of the structure of type sdns_rr_PTR.

Parameters

ptr	A pointer to the structure

sdns_free_rr_RRSIG()

void sdns_free_rr_RRSIG

(

sdns_rr_RRSIG *

rrsig

)

Free the memory of the structure of type sdns_rr_RRSIG.

Parameters

rrsig

A pointer to the structure

sdns_free_rr_SOA()

void sdns_free_rr_SOA

(

sdns_rr_SOA *

soa

)

Free the memory of the structure of type sdns_rr_SOA.

Parameters

soa	A pointer to the structure

sdns_free_rr_SRV()

void sdns_free_rr_SRV

(

sdns_rr_SRV *

srv

)

Free the memory of the structure of type sdns_rr_SRV.

Parameters

srv	A pointer to the structure

sdns_free_rr_TXT()

void sdns_free_rr_TXT

(

sdns_rr_TXT *

txt

)

Free the memory of the structure of type sdns_rr_TXT.

Parameters

txt	A pointer to the structure

sdns_free_rr_URI()

void sdns_free_rr_URI

(

sdns_rr_URI *

uri

)

Free the memory of the structure of type sdns_rr_URI.

Parameters

uri	A pointer to the structure

sdns_free_section()

void sdns_free_section

(

sdns_rr *

rr

)

free a DNS resource record no matter of the type

Parameters

rr	a pointer to the memory of sdns_rr which holds the resource record section to be freed

Returns

nothing

sdns_from_wire()

int sdns_from_wire

(

sdns_context *

ctx

)

Converts the raw data received from socket (bytes) to a DNS packet.

Parameters

ctx	A pointer to DNS context created by sdns_init_context().

A description of all error codes returned by this method can be retrieved by calling sdns_error_string() function.

Returns

0 on success, other values in case of failure.

char * buff = (char*)malloc(1024);
ssize_t received = recvfrom(socketfd, buff, 1024, ......)
// assume that we received "received" bytes from socket stored in "buff"
// here is how we can convert it to DNS packet.
sdns_context * ctx = sdns_init_context();
// I am not doing error checks but you must always make sure ctx is not NULL
// After you are done with error checks....
ctx->raw = buff;
ctx->raw_len = received;
int res = sdns_from_wire(ctx);
if (res != 0){
     // we need to handle the error, we can call sdns_error_string
}
// we have a parsed DNS packet in ctx->msg
sdns_neat_print_dns(ctx);

sdns_init_context()

sdns_context * sdns_init_context

(

void

)

Initialize and create a new DNS context.

This function is responsible for creating a new context for DNS.

For each DNS packet, you must create a new context. This function does nothing more than creating a structure and allocating the necessary memories.

sdns_init_message()

sdns_message * sdns_init_message

(

void

)

Initialize a DNS message structure (sdns_message).

Users don't need to this method directly. We use this method internally when we call sdns_init_context().

sdns_init_rr()

sdns_rr * sdns_init_rr	(	char *	name,
		uint16_t	type,
		uint16_t	class,
		uint32_t	ttl,
		uint16_t	rdlength,
		uint8_t	decoded,
		void *	rdata
	)

Initialize an RR data structure.

Parameters

name	a pointer to the name of the resource record
type	the type of the resource record
class	the class of the resource record
ttl	the ttl of the resource record
rdlength	the length of the rdata section of this resource record
decoded	if resource record is decoded (1) or not (0).
rdata	a pointer to the raw data (if decode = 0) or a structure (decoded =1)

One can use this method to add a resource record to a DNS packet that is not supported by this library. For all RRs that this library support, we have a sdns_init_rr_*() function. If you have a new type to add, you can use this method to create it.

Returns

an instance of sdns_rr structure on success. NULL on fail.

sdns_init_rr_A()

sdns_rr_A * sdns_init_rr_A

(

uint32_t

ipaddress

)

Initialize a structure of sdns_rr_A.

Parameters

ipaddress

an unsigned 32bit integer representing the IPv4

The address is an unsigned integer value for example 2130706433 means 127.0.0.1

Returns

a pointer to sdns_rr_A structure on success and NULL on fail

sdns_init_rr_AAAA()

sdns_rr_AAAA * sdns_init_rr_AAAA

(

char *

aaaa

)

Initialize a structure of sdns_rr_AAAA.

Parameters

aaaa	pointer to the memory address that keeps the 16 bytes of IPv6

NOTE: do not free the 'aaaa' pointer after calling this method. This function does not copy the memory but use the pointer.

Returns

a pointer to sdns_rr_AAAA structure on success and NULL on fail

sdns_init_rr_CAA()

sdns_rr_CAA * sdns_init_rr_CAA	(	uint8_t	flag,
		char *	tag,
		uint8_t	tag_len,
		char *	value,
		uint16_t	value_len
	)

Initialize a structure of sdns_rr_CAA.

Parameters

flag	one byte flag specified in Section 3 of RFC 6844
tag	a pointer to tag value specified in RFC 6844
tag_len	the length of the tag filed. max value can be 255.
value	a pointer to 'value' value specified in RFC 6844 @pram NOTE: Do not free the 'tag' and 'value' after calling this method. This function does not copy the memory but use a pointer to the memory you allocated. Make sure it's a heap-allocated memory to avoid memory leak.

Returns

a pointer to sdns_rr_CAA structure on success and NULL on fail

sdns_init_rr_CNAME()

sdns_rr_CNAME * sdns_init_rr_CNAME

(

char *

cname

)

Initialize a structure of sdns_rr_CNAME.

Parameters

cname

pointer to the memory address that keeps the cname data

NOTE: do not free the 'cname' pointer after calling this method. This function does not copy the memory but use the pointer. Make sure it's a heap-allocated memory to avoid memory leak.

Returns

a pointer to sdns_rr_CNAME structure on success and NULL on fail

sdns_init_rr_L32()

sdns_rr_L32 * sdns_init_rr_L32	(	uint16_t	preference,
		uint32_t	locator32
	)

Initialize a structure of sdns_rr_L32.

Parameters

preference	16bit unsigned integer showing the preference value of the L32 record
locator32	32bit unsigned integer for Locator32

Returns

a pointer to sdns_rr_L32 structure on success and NULL on fail

sdns_init_rr_L64()

sdns_rr_L64 * sdns_init_rr_L64	(	uint16_t	preference,
		char *	locator64
	)

Initialize a structure of sdns_rr_L64.

Parameters

preference	16bit unsigned integer showing the preference value of the L64 record
locator64	pointer to the memory address that keeps the Locator64 data

NOTE: do not free the 'locator64' pointer after calling this method. This function does not copy the memory but use the pointer. Make sure it's a heap-allocated memory to avoid memory leak.

NOTE: locator64 is exactly 8 bytes based on RFC 6742

Returns

a pointer to sdns_rr_L64 structure on success and NULL on fail

sdns_init_rr_LP()

sdns_rr_LP * sdns_init_rr_LP	(	uint16_t	preference,
		char *	fqdn
	)

Initialize a structure of sdns_rr_LP.

Parameters

preference	16bit unsigned integer showing the preference value of the LP record
fqdn	pointer to the memory address that keeps the fully-qualified-domain-name data

NOTE: do not free the 'fqdn' pointer after calling this method. This function does not copy the memory but use the pointer. Make sure it's a heap-allocated memory to avoid memory leak.

Returns

a pointer to sdns_rr_LP structure on success and NULL on fail

sdns_init_rr_MX()

sdns_rr_MX * sdns_init_rr_MX	(	uint16_t	preference,
		char *	exchange
	)

Initialize a structure of sdns_rr_MX.

Parameters

preference	a 16-bit integer for the prereference of the MX record
exchange	pointer to the memory address that keeps the 'exchange' data

NOTE: do not free the 'exchange' pointer after calling this method. This function does not copy the memory but use the pointer. Make sure it's a heap-allocated memory to avoid memory leak.

Returns

a pointer to sdns_rr_MX structure on success and NULL on fail

sdns_init_rr_NID()

sdns_rr_NID * sdns_init_rr_NID	(	uint16_t	preference,
		char *	nodid
	)

Initialize a structure of sdns_rr_NID.

Parameters

preference	16bit unsigned integer showing the preference value of the NID record
nodid	pointer to the memory address that keeps the NodeId data

NOTE: do not free the 'nodeid' pointer after calling this method. This function does not copy the memory but use the pointer. Make sure it's a heap-allocated memory to avoid memory leak.

NOTE: nodeid is exactly 8 bytes based on RFC 6742

Returns

a pointer to sdns_rr_NID structure on success and NULL on fail

sdns_init_rr_NS()

sdns_rr_NS * sdns_init_rr_NS

(

char *

nsdname

)

Initialize a structure of sdns_rr_NS.

Parameters

nsdname

pointer to the memory address that keeps the nsdname data (e.g., ns1.google.com)

NOTE: do not free the 'nsdname' pointer after calling this method. This function does not copy the memory but use the pointer. Make sure it's a heap-allocated memory to avoid memory leak.

Returns

a pointer to sdns_rr_NS structure on success and NULL on fail

sdns_init_rr_PTR()

sdns_rr_PTR * sdns_init_rr_PTR

(

char *

ptrdname

)

Initialize a structure of sdns_rr_PTR.

Parameters

ptrdname

pointer to the memory address that keeps the ptrdname data

NOTE: do not free the 'ptrdname' pointer after calling this method. This function does not copy the memory but use the pointer. Make sure it's a heap-allocated memory to avoid memory leak.

Returns

a pointer to sdns_rr_PTR structure on success and NULL on fail

sdns_init_rr_SRV()

sdns_rr_SRV * sdns_init_rr_SRV	(	uint16_t	Priority,
		uint16_t	Weight,
		uint16_t	Port,
		char *	target
	)

Initialize a structure of sdns_rr_SRV.

Parameters

Priority	16-bit unsigned value for the priority of the SRV record
Weight	16-bit unsigned value for the weight of the SRV record
Port	16-bit unsigned value for the port of the SRV record
target	A pointer to the target value of the SRV record

NOTE: do not free the 'target' pointer after calling this method. This function does not copy the memory but use the pointer. Make sure it's a heap-allocated memory to avoid memory leak.

Returns

a pointer to sdns_rr_SRV structure on success and NULL on fail

sdns_init_rr_TXT()

sdns_rr_TXT * sdns_init_rr_TXT	(	char *	data,
		uint16_t	data_len
	)

Initialize a structure of sdns_rr_TXT.

Parameters

data	pointer to the memory address that keeps the data
data_len	length of the data pointed by 'data' pointer

NOTE: the 'data' pointer is not necessarily a nul-terminated string. That's why we need to know the length of the data.

NOTE: do not free the 'data' pointer after calling this method. This function does not copy the memory but use the pointer. Make sure it's a heap-allocated memory to avoid memory leak.

Returns

a pointer to sdns_rr_TXT structure on success and NULL on fail

sdns_make_query()

int sdns_make_query	(	sdns_context *	ctx,
		sdns_rr_type	qtype,
		sdns_q_class	cls,
		char *	qname,
		int	enable_edns0
	)

Creates a DNS question query.

Parameters

ctx	A pointer to the sdns_context structure created by sdns_init_context()
qtype	one of the possible values of sdns_rr_type
cls	one of the possible values of sdns_q_class
qname	a pointer to the question name.
enable_edns0	a value of 0 or 1 specifying if the packet is EDNS0 aware or not.

qname pointer must be a pointer to char* and not a local buffer. when you call sdns_free_context(), the function try to free() the qname.

In case the function returns a value other than 0, you can call sdns_error_string() to get the description of the error code.

Returns

A successful call to this function will return 0 and other values indicate errors.

char *error = NULL;
sdns_context * ctx = sdns_init_context();
if (NULL == ctx)
    return 1;
// Let's make the most trivial and basic DNS packet. (google.com IN A)
// notice how I use strdup to pass a heap-allocated pointer to the function.
int res = sdns_make_query(ctx, sdns_rr_type_A, sdns_q_class_IN, strdup("google.com"), 1);
if (res != 0){
    sdns_error_string(res, &error);
    fprintf(stderr, "%s\n", error);
    free(error);
    sdns_free_context(ctx);
    return 1;
}
// the packet has been created successfully. We can convert it to wire format and send it.
res = sdns_to_wire(ctx);
if (res != sdns_rcode_NoError){
    sdns_error_string(res, &error);
    fprintf(stderr, "%s\n", error);
    free(error);
    sdns_free_context(ctx);
    return 1;
}
// ctx->raw is ready for the socket and ctx->raw_len is its length.
// ctx->raw and ctx->raw_len can be used in sendto() function.
// after we are done, we need to free the context.
sdns_free_context(ctx);

sdns_rr_type_to_string()

void sdns_rr_type_to_string	(	uint16_t	t,
		char *	buff
	)

Gets the string representation of the TYPE tp in to buffer

Parameters

t	A 16bit integer, one of the possible values of sdns_rr_type
buff	A pointer to the user-provided buffer

The buffer must be long enough to cover all types.

Currently, a buffer of length 20 is enough.

sdns_to_wire()

int sdns_to_wire

(

sdns_context *

ctx

)

Coverts a DNS context to binary format.

Parameters

ctx	A pointer to DNS context created by sdns_init_context().

Returns

0 on success other values for failure.

This is one of the main APIs provided by this library. Whenever you want to send data to the socket, you must call this function first to create the binary data.

Look at the provided example for sdns_make_query() for more info.