RULI Resolver API

This page documents the API for the asynchronous, stub, DNS resolver used internally by RULI.

The resolver interface operates asynchronously in an event-driven fashion. The application registers a callback function prior to submitting the desired query. Actually, the callback function is an argument for the query. When the answer arrives, the resolver asynchronously dispatches the registered callback passing the proper result.

This resolver API is not tied to SRV records. It's a general-purpose library aimed at querying recursive DNS servers. However, the resource records provided in the server answer are not interpreted; it's up to the application to handle them.

The asynchronous event management interface used here is provided by the excellent Liboop library.

• Main Entry Points
• Auxiliary Functions
• Types
• Functions

Main Entry Points

Auxiliary Functions

Types

/* Opaque resolver context */

typedef struct {
  oop_source  *res_source;      /* event source */
  ruli_list_t *res_server_list; /* list of in_addr* */
  int         res_retry;        /* retry limit for each server */
  int         res_timeout;      /* query timeout for each server */
} ruli_res_t;


struct ruli_res_query_t;
typedef struct ruli_res_query_t ruli_res_query_t;


typedef void *(*ruli_res_query_call_t)(ruli_res_query_t *qry,
				       void *arg);

/* Opaque query context */

struct ruli_res_query_t {
  /* 
   * input
   */
  ruli_res_query_call_t q_on_answer;      /* query callback function */
  void                  *q_on_answer_arg; /* query callback opaque argument */
  char                  *q_domain;        /* query domain (encoded, uncompressed) */
  int                   q_domain_len;     /* domain length */
  int                   q_class;          /* query class (encoded, uncompressed) */
  int                   q_type;           /* query type */

  /* 
   * output
   */
  char              *answer_buf;
  int               answer_buf_size;
  int               answer_msg_len;
  int               answer_code;
  ruli_msg_header_t answer_header;
};

Functions

• oop_source *res_source;
• ruli_list_t *res_server_list;
• int res_retry;
• int res_timeout;

• ruli_res_query_call_t q_on_answer;
• void *q_on_answer_arg;
• char *q_domain;
• int q_domain_len;
• int q_class;
• int q_type;

• char *answer_buf;
• int answer_buf_size;
• int answer_msg_len;
• int answer_code;
• ruli_msg_header_t answer_header;