diff options
Diffstat (limited to 'pjlib-util/include/pjlib-util/dns.h')
| -rw-r--r-- | pjlib-util/include/pjlib-util/dns.h | 164 |
1 files changed, 127 insertions, 37 deletions
diff --git a/pjlib-util/include/pjlib-util/dns.h b/pjlib-util/include/pjlib-util/dns.h index cb6a28f2..d431b0da 100644 --- a/pjlib-util/include/pjlib-util/dns.h +++ b/pjlib-util/include/pjlib-util/dns.h @@ -22,7 +22,7 @@ /** * @file dns.h - * @brief Asynchronous DNS Name Resolution/resolver + * @brief Low level DNS message parsing and packetization. */ #include <pj/types.h> @@ -31,16 +31,35 @@ PJ_BEGIN_DECL /** - * @defgroup PJ_DNS_RESOLVER Asynchronous DNS Name Resolution/resolver + * @defgroup PJ_DNS Low-level DNS message parsing and packetization * @ingroup PJ * @{ * - * This module provides services to performing asynchronous DNS resolution. + * This module provides low-level services to parse and packetize DNS queries + * and responses. The functions support building a DNS query packet and parse + * the data in the DNS response. + * + * To create a DNS query packet, application should call #pj_dns_make_query() + * function, specifying the desired DNS query type, the name to be resolved, + * and the buffer where the DNS packet will be built into. + * + * When incoming DNS query or response packet arrives, application can use + * #pj_dns_parse_packet() to parse the TCP/UDP payload into parsed DNS packet + * structure. + * + * This module does not provide any networking functionalities to send or + * receive DNS packets. This functionality should be provided by higher layer + * modules such as @ref PJ_DNS_RESOLVER. */ +enum +{ + PJ_DNS_CLASS_IN = 1 /**< DNS class IN. */ +}; + /** * This enumeration describes standard DNS record types as described by - * RFC 1035. + * RFC 1035, RFC 2782, and others. */ typedef enum pj_dns_type { @@ -158,31 +177,69 @@ typedef struct pj_dns_hdr #define PJ_DNS_GET_QR(val) (((val) & PJ_DNS_SET_QR(1)) >> 15) +/** + * These constants describe DNS RCODEs. Application can fold these constants + * into PJLIB pj_status_t namespace by calling #PJ_STATUS_FROM_DNS_RCODE() + * macro. + */ +typedef enum pj_dns_rcode +{ + PJ_DNS_RCODE_FORMERR = 1, /**< Format error. */ + PJ_DNS_RCODE_SERVFAIL = 2, /**< Server failure. */ + PJ_DNS_RCODE_NXDOMAIN = 3, /**< Name Error. */ + PJ_DNS_RCODE_NOTIMPL = 4, /**< Not Implemented. */ + PJ_DNS_RCODE_REFUSED = 5, /**< Refused. */ + PJ_DNS_RCODE_YXDOMAIN = 6, /**< The name exists. */ + PJ_DNS_RCODE_YXRRSET = 7, /**< The RRset (name, type) exists. */ + PJ_DNS_RCODE_NXRRSET = 8, /**< The RRset (name, type) doesn't exist*/ + PJ_DNS_RCODE_NOTAUTH = 9, /**< Not authorized. */ + PJ_DNS_RCODE_NOTZONE = 10 /**< The zone specified is not a zone. */ + +} pj_dns_rcode; + /** - * This constants describes record types in the DNS packet. + * This constant specifies the maximum names to keep in the temporary name + * table when performing name compression scheme when duplicating DNS packet + * (the #pj_dns_packet_dup() function). + * + * Generally name compression is desired, since it saves some memory (see + * PJ_DNS_RESOLVER_RES_BUF_SIZE setting). However it comes at the expense of + * a little processing overhead to perform name scanning and also a little + * bit more stack usage (8 bytes per entry on 32bit platform). + * + * Default: 16 */ -typedef enum pj_dns_rec_type +#ifndef PJ_DNS_MAX_NAMES_IN_NAMETABLE +# define PJ_DNS_MAX_NAMES_IN_NAMETABLE 16 +#endif + + +/** + * This structure describes a DNS query record. + */ +typedef struct pj_dns_parsed_query { - DNS_QUERY_REC, /**< The record is a query record */ - DNS_RR_REC, /**< The record is resource record */ - DNS_NS_REC, /**< The record is name server record */ - DNS_REC_AR, /**< The record is additional RR. */ -} pj_dns_rec_type; + pj_str_t name; /**< The domain in the query. */ + pj_uint16_t type; /**< Type of the query (pj_dns_type) */ + pj_uint16_t dnsclass; /**< Network class (PJ_DNS_CLASS_IN=1) */ +} pj_dns_parsed_query; /** - * This structure describes a Resource Record parsed from the DNS response. + * This structure describes a Resource Record parsed from the DNS packet. * All integral values are in host byte order. */ typedef struct pj_dns_parsed_rr { pj_str_t name; /**< The domain name which this rec pertains. */ pj_uint16_t type; /**< RR type code. */ - pj_uint16_t class_; /**< Class of data (normally 1, for IN). */ + pj_uint16_t dnsclass; /**< Class of data (PJ_DNS_CLASS_IN=1). */ pj_uint32_t ttl; /**< Time to live. */ pj_uint16_t rdlength; /**< Resource data length. */ - void *data; /**< Pointer to the raw resource data. */ + void *data; /**< Pointer to the raw resource data, only + when the type is not known. If it is known, + the data will be put in rdata below. */ /** For resource types that are recognized/supported by this library, * the parsed resource data will be placed in this rdata union. @@ -223,21 +280,29 @@ typedef struct pj_dns_parsed_rr /** - * This structure describes the response parsed from the raw DNS response. - * Note that all integral values in the parsed response are represented in + * This structure describes the parsed repersentation of the raw DNS packet. + * Note that all integral values in the parsed packet are represented in * host byte order. */ -typedef struct pj_dns_parsed_response +typedef struct pj_dns_parsed_packet { - pj_dns_hdr hdr; /**< Pointer to DNS hdr, in host byte order */ - pj_dns_parsed_rr *ans; /**< Array of DNS RR answer. */ - pj_dns_parsed_rr *ns; /**< Array of NS record in the answer. */ - pj_dns_parsed_rr *arr; /**< Array of additional RR answer. */ -} pj_dns_parsed_response; + pj_dns_hdr hdr; /**< Pointer to DNS hdr, in host byte order */ + pj_dns_parsed_query *q; /**< Array of DNS queries. */ + pj_dns_parsed_rr *ans; /**< Array of DNS RR answer. */ + pj_dns_parsed_rr *ns; /**< Array of NS record in the answer. */ + pj_dns_parsed_rr *arr; /**< Array of additional RR answer. */ +} pj_dns_parsed_packet; /** - * Create DNS query packet to resolve the specified names. + * Create DNS query packet to resolve the specified names. This function + * can be used to build any types of DNS query, such as A record or DNS SRV + * record. + * + * Application specifies the type of record and the name to be queried, + * and the function will build the DNS query packet into the buffer + * specified. Once the packet is successfully built, application can send + * the packet via TCP or UDP connection. * * @param packet The buffer to put the DNS query packet. * @param size On input, it specifies the size of the buffer. @@ -245,7 +310,7 @@ typedef struct pj_dns_parsed_response * the DNS query packet. * @param id DNS query ID to associate DNS response with the * query. - * @param qtype DNS type of record to be queried. + * @param qtype DNS type of record to be queried (see #pj_dns_type). * @param name Name to be queried from the DNS server. * * @return PJ_SUCCESS on success, or the appropriate error code. @@ -253,30 +318,55 @@ typedef struct pj_dns_parsed_response PJ_DECL(pj_status_t) pj_dns_make_query(void *packet, unsigned *size, pj_uint16_t id, - pj_dns_type qtype, + int qtype, const pj_str_t *name); /** - * Parse raw DNS response packet into DNS response structure. + * Parse raw DNS packet into parsed DNS packet structure. This function is + * able to parse few DNS resource records such as A record, PTR record, + * CNAME record, NS record, and SRV record. * - * @param pool Pool to allocate memory for the parsed response. - * @param packet - * @param size - * @param p_res + * @param pool Pool to allocate memory for the parsed packet. + * @param packet Pointer to the DNS packet (the TCP/UDP payload of + * the raw packet). + * @param size The size of the DNS packet. + * @param p_res Pointer to store the resulting parsed packet. * * @return PJ_SUCCESS on success, or the appropriate error code. */ -PJ_DECL(pj_status_t) pj_dns_parse_response(pj_pool_t *pool, - const void *packet, - unsigned size, - pj_dns_parsed_response **p_res); +PJ_DECL(pj_status_t) pj_dns_parse_packet(pj_pool_t *pool, + const void *packet, + unsigned size, + pj_dns_parsed_packet **p_res); + +/** + * Duplicate DNS packet. + * + * @param pool The pool to allocate memory for the duplicated packet. + * @param p The DNS packet to be cloned. + * @p_dst Pointer to store the cloned DNS packet. + */ +PJ_DECL(void) pj_dns_packet_dup(pj_pool_t *pool, + const pj_dns_parsed_packet*p, + pj_dns_parsed_packet **p_dst); + + +/** + * Utility function to get the type name string of the specified DNS type. + * + * @param type DNS type (see #pj_dns_type). + * + * @return String name of the type (e.g. "A", "SRV", etc.). + */ +PJ_DECL(const char *) pj_dns_get_type_name(int type); + /** - * Dump DNS response to standard log. + * Dump DNS packet to standard log. * - * @param res The DNS response. + * @param res The DNS packet. */ -PJ_DECL(void) pj_dns_dump_response(const pj_dns_parsed_response *res); +PJ_DECL(void) pj_dns_dump_packet(const pj_dns_parsed_packet *res); /** |