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rdns.h
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/*
* Copyright (c) 2013-2014, Vsevolod Stakhov
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY AUTHOR ''AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL AUTHOR BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef RDNS_H
#define RDNS_H
#include <sys/types.h>
#include <stddef.h>
#include <stdint.h>
#include <stdbool.h>
#include <stdarg.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#ifdef __cplusplus
extern "C" {
#endif
struct rdns_reply;
struct rdns_request;
struct rdns_io_channel;
typedef void (*dns_callback_type) (struct rdns_reply *reply, void *arg);
enum rdns_request_type {
RDNS_REQUEST_A = 1,
RDNS_REQUEST_NS = 2,
RDNS_REQUEST_SOA = 6,
RDNS_REQUEST_PTR = 12,
RDNS_REQUEST_MX = 15,
RDNS_REQUEST_TXT = 16,
RDNS_REQUEST_SRV = 33,
RDNS_REQUEST_SPF = 99,
RDNS_REQUEST_AAAA = 28,
RDNS_REQUEST_TLSA = 52,
RDNS_REQUEST_ANY = 255
};
union rdns_reply_element_un {
struct {
struct in_addr addr;
} a;
struct {
struct in6_addr addr;
} aaa;
struct {
char *name;
} ptr;
struct {
char *name;
} ns;
struct {
char *name;
uint16_t priority;
} mx;
struct {
char *data;
} txt;
struct {
uint16_t priority;
uint16_t weight;
uint16_t port;
char *target;
} srv;
struct {
char *mname;
char *admin;
uint32_t serial;
int32_t refresh;
int32_t retry;
int32_t expire;
uint32_t minimum;
} soa;
struct {
uint8_t usage;
uint8_t selector;
uint8_t match_type;
uint16_t datalen;
uint8_t *data;
} tlsa;
};
struct rdns_reply_entry {
union rdns_reply_element_un content;
uint16_t type;
int32_t ttl;
struct rdns_reply_entry *prev, *next;
};
enum dns_rcode {
RDNS_RC_NOERROR = 0,
RDNS_RC_FORMERR = 1,
RDNS_RC_SERVFAIL = 2,
RDNS_RC_NXDOMAIN = 3,
RDNS_RC_NOTIMP = 4,
RDNS_RC_REFUSED = 5,
RDNS_RC_YXDOMAIN = 6,
RDNS_RC_YXRRSET = 7,
RDNS_RC_NXRRSET = 8,
RDNS_RC_NOTAUTH = 9,
RDNS_RC_NOTZONE = 10,
RDNS_RC_TIMEOUT = 11,
RDNS_RC_NETERR = 12,
RDNS_RC_NOREC = 13
};
struct rdns_reply {
struct rdns_request *request;
struct rdns_resolver *resolver;
struct rdns_reply_entry *entries;
const char *requested_name;
enum dns_rcode code;
bool authenticated;
};
typedef void (*rdns_periodic_callback)(void *user_data);
struct rdns_async_context {
void *data;
void* (*add_read)(void *priv_data, int fd, void *user_data);
void (*del_read)(void *priv_data, void *ev_data);
void* (*add_write)(void *priv_data, int fd, void *user_data);
void (*del_write)(void *priv_data, void *ev_data);
void* (*add_timer)(void *priv_data, double after, void *user_data);
void (*repeat_timer)(void *priv_data, void *ev_data);
void (*del_timer)(void *priv_data, void *ev_data);
void* (*add_periodic)(void *priv_data, double after,
rdns_periodic_callback cb, void *user_data);
void (*del_periodic)(void *priv_data, void *ev_data);
void (*cleanup)(void *priv_data);
};
struct rdns_upstream_elt {
void *server;
void *lib_data;
};
struct rdns_upstream_context {
void *data;
struct rdns_upstream_elt* (*select)(const char *name,
size_t len, void *ups_data);
struct rdns_upstream_elt* (*select_retransmit)(const char *name,
size_t len, void *ups_data);
unsigned int (*count)(void *ups_data);
void (*ok)(struct rdns_upstream_elt *elt, void *ups_data);
void (*fail)(struct rdns_upstream_elt *elt, void *ups_data);
};
/**
* Type of rdns plugin
*/
enum rdns_plugin_type {
RDNS_PLUGIN_CURVE = 0
};
typedef ssize_t (*rdns_network_send_callback) (struct rdns_request *req, void *plugin_data);
typedef ssize_t (*rdns_network_recv_callback) (struct rdns_io_channel *ioc, void *buf,
size_t len, void *plugin_data, struct rdns_request **req_out);
typedef void (*rdns_network_finish_callback) (struct rdns_request *req, void *plugin_data);
typedef void (*rdns_plugin_dtor_callback) (struct rdns_resolver *resolver, void *plugin_data);
struct rdns_plugin {
enum rdns_plugin_type type;
union {
struct {
rdns_network_send_callback send_cb;
rdns_network_recv_callback recv_cb;
rdns_network_finish_callback finish_cb;
} curve_plugin;
} cb;
rdns_plugin_dtor_callback dtor;
void *data;
};
/*
* RDNS logger types
*/
/*
* These types are somehow compatible with glib
*/
enum rdns_log_level {
RDNS_LOG_ERROR = 1 << 3,
RDNS_LOG_WARNING = 1 << 4,
RDNS_LOG_INFO = 1 << 6,
RDNS_LOG_DEBUG = 1 << 7
};
typedef void (*rdns_log_function) (
void *log_data, //!< opaque data pointer
enum rdns_log_level level, //!< level of message
const char *function, //!< calling function
const char *format, //!< format
va_list args //!< set of arguments
);
struct rdns_request_name {
char *name;
enum rdns_request_type type;
unsigned int len;
};
/*
* RDNS API
*/
/**
* Create DNS resolver structure
*/
struct rdns_resolver *rdns_resolver_new (void);
/**
* Bind resolver to specified async context
* @param ctx
*/
void rdns_resolver_async_bind (struct rdns_resolver *resolver,
struct rdns_async_context *ctx);
/**
* Enable stub dnssec resolver
* @param resolver
*/
void rdns_resolver_set_dnssec (struct rdns_resolver *resolver, bool enabled);
/**
* Add new DNS server definition to the resolver
* @param resolver resolver object
* @param name name of DNS server (should be ipv4 or ipv6 address)
* @param priority priority (can be 0 for fair round-robin)
* @param io_cnt a number of sockets that are simultaneously opened to this server
* @return opaque pointer that could be used to select upstream
*/
void* rdns_resolver_add_server (struct rdns_resolver *resolver,
const char *name, unsigned int port,
int priority, unsigned int io_cnt);
/**
* Load nameservers definition from resolv.conf file
* @param resolver resolver object
* @param path path to resolv.conf file (/etc/resolv.conf typically)
* @return true if resolv.conf has been parsed
*/
bool rdns_resolver_parse_resolv_conf (struct rdns_resolver *resolver,
const char *path);
typedef bool (*rdns_resolv_conf_cb) (struct rdns_resolver *resolver,
const char *name, unsigned int port,
int priority, unsigned int io_cnt, void *ud);
/**
* Parse nameservers calling the specified callback for each nameserver
* @param resolve resolver object
* @param path path to resolv.conf file (/etc/resolv.conf typically)
* @param cb callback to call
* @param ud userdata for callback
* @return true if resolv.conf has been parsed
*/
bool rdns_resolver_parse_resolv_conf_cb (struct rdns_resolver *resolver,
const char *path, rdns_resolv_conf_cb cb, void *ud);
/**
* Set an external logger function to log messages from the resolver
* @param resolver resolver object
* @param logger logger callback
* @param log_data opaque data
*/
void rdns_resolver_set_logger (struct rdns_resolver *resolver,
rdns_log_function logger, void *log_data);
/**
* Set log level for an internal logger (stderr one)
* @param resolver resolver object
* @param level desired log level
*/
void rdns_resolver_set_log_level (struct rdns_resolver *resolver,
enum rdns_log_level level);
/**
* Set upstream library for selecting DNS upstreams
* @param resolver resolver object
* @param ups_ctx upstream functions
* @param ups_data opaque data
*/
void rdns_resolver_set_upstream_lib (struct rdns_resolver *resolver,
struct rdns_upstream_context *ups_ctx,
void *ups_data);
/**
* Set maximum number of dns requests to be sent to a socket to be refreshed
* @param resolver resolver object
* @param max_ioc_uses unsigned count of socket usage limit
* @param check_time specifies how often to check for sockets and refresh them
*/
void rdns_resolver_set_max_io_uses (struct rdns_resolver *resolver,
uint64_t max_ioc_uses, double check_time);
/**
* Register new plugin for rdns resolver
* @param resolver
* @param plugin
*/
void rdns_resolver_register_plugin (struct rdns_resolver *resolver,
struct rdns_plugin *plugin);
/**
* Init DNS resolver
* @param resolver
* @return
*/
bool rdns_resolver_init (struct rdns_resolver *resolver);
/**
* Decrease refcount for a resolver and free it if refcount is 0
* @param resolver
*/
void rdns_resolver_release (struct rdns_resolver *resolver);
/**
* Make a DNS request
* @param resolver resolver object
* @param cb callback to call on resolve completing
* @param ud user data for callback
* @param timeout timeout in seconds
* @param repeats how much time to retransmit query
* @param queries how much RR queries to send
* @param ... -> queries in format: <query_type>[,type_argument[,type_argument...]]
* @return opaque request object or NULL
*/
struct rdns_request* rdns_make_request_full (
struct rdns_resolver *resolver,
dns_callback_type cb,
void *cbdata,
double timeout,
unsigned int repeats,
unsigned int queries,
...
);
/**
* Get textual presentation of DNS error code
*/
const char *rdns_strerror (enum dns_rcode rcode);
/**
* Get textual presentation of DNS request type
*/
const char *rdns_strtype (enum rdns_request_type type);
/**
* Parse string and return request type
* @param str
* @return
*/
enum rdns_request_type rdns_type_fromstr (const char *str);
/**
* Parse string and return error code
* @param str
* @return
*/
enum dns_rcode rdns_rcode_fromstr (const char *str);
/**
* Increase refcount for a request
* @param req
* @return
*/
struct rdns_request* rdns_request_retain (struct rdns_request *req);
/**
* Decrease refcount for a request and free it if refcount is 0
* @param req
*/
void rdns_request_release (struct rdns_request *req);
/**
* Check whether a request contains `type` request
* @param req request object
* @param type check for a specified type
* @return true if `type` has been requested
*/
bool rdns_request_has_type (struct rdns_request *req, enum rdns_request_type type);
/**
* Return requested name for a request
* @param req request object
* @return requested name as it was passed to `rdns_make_request`
*/
const struct rdns_request_name* rdns_request_get_name (struct rdns_request *req,
unsigned int *count);
/**
* Return PTR string for a request (ipv4 or ipv6) addresses
* @param str string representation of IP address
* @return name to resolve or NULL if `str` is not an IP address; caller must free result when it is unused
*/
char * rdns_generate_ptr_from_str (const char *str);
/**
* Format DNS name of the packet punycoding if needed
* @param req request
* @param name name string
* @param namelen length of name
*/
bool rdns_format_dns_name (struct rdns_resolver *resolver,
const char *name, size_t namelen,
char **out, size_t *outlen);
/*
* Private functions used by async libraries as callbacks
*/
void rdns_process_read (int fd, void *arg);
void rdns_process_timer (void *arg);
void rdns_process_retransmit (int fd, void *arg);
#ifdef __cplusplus
}
#endif
#endif