dns_core.h File Reference

Core DNS API. More...

#include "asterisk/netsock2.h"

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Typedefs
typedef void(*	ast_dns_resolve_callback) (const struct ast_dns_query *query)
	Callback invoked when a query completes. More...

Functions
void *	ast_dns_query_get_data (const struct ast_dns_query *query)
	Get the user specific data of a DNS query. More...
const char *	ast_dns_query_get_name (const struct ast_dns_query *query)
	Get the name queried in a DNS query. More...
struct ast_dns_result *	ast_dns_query_get_result (const struct ast_dns_query *query)
	Get the result information for a DNS query. More...
int	ast_dns_query_get_rr_class (const struct ast_dns_query *query)
	Get the record resource class of a DNS query. More...
int	ast_dns_query_get_rr_type (const struct ast_dns_query *query)
	Get the record resource type of a DNS query. More...
const char *	ast_dns_record_get_data (const struct ast_dns_record *record)
	Retrieve the raw DNS record. More...
size_t	ast_dns_record_get_data_size (const struct ast_dns_record *record)
	Retrieve the size of the raw DNS record. More...
const struct ast_dns_record *	ast_dns_record_get_next (const struct ast_dns_record *record)
	Get the next DNS record. More...
int	ast_dns_record_get_rr_class (const struct ast_dns_record *record)
	Get the resource record class of a DNS record. More...
int	ast_dns_record_get_rr_type (const struct ast_dns_record *record)
	Get the resource record type of a DNS record. More...
int	ast_dns_record_get_ttl (const struct ast_dns_record *record)
	Get the TTL of a DNS record. More...
int	ast_dns_resolve (const char *name, int rr_type, int rr_class, struct ast_dns_result **result)
	Synchronously resolve a DNS query. More...
struct ast_dns_query_active *	ast_dns_resolve_async (const char *name, int rr_type, int rr_class, ast_dns_resolve_callback callback, void *data)
	Asynchronously resolve a DNS query. More...
int	ast_dns_resolve_cancel (struct ast_dns_query_active *active)
	Cancel an asynchronous DNS resolution. More...
int	ast_dns_resolve_ipv6_and_ipv4 (struct ast_sockaddr *address, const char *host, const char *port)
	Synchronously resolves host to an AAAA or A record. More...
void	ast_dns_result_free (struct ast_dns_result *result)
	Free the DNS result information. More...
const char *	ast_dns_result_get_answer (const struct ast_dns_result *result)
	Get the raw DNS answer from a DNS result. More...
unsigned int	ast_dns_result_get_bogus (const struct ast_dns_result *result)
	Get whether the result is bogus or not. More...
const char *	ast_dns_result_get_canonical (const struct ast_dns_result *result)
	Get the canonical name of the result. More...
int	ast_dns_result_get_lowest_ttl (const struct ast_dns_result *result)
	Retrieve the lowest TTL from a result. More...
unsigned int	ast_dns_result_get_rcode (const struct ast_dns_result *result)
	Get the error rcode of a DN result. More...
const struct ast_dns_record *	ast_dns_result_get_records (const struct ast_dns_result *result)
	Get the first record of a DNS Result. More...
unsigned int	ast_dns_result_get_secure (const struct ast_dns_result *result)
	Get whether the result is secure or not. More...

Detailed Description

Core DNS API.

Author

Joshua Colp jcolp.nosp@m.@dig.nosp@m.ium.c.nosp@m.om

Definition in file dns_core.h.

Typedef Documentation

ast_dns_resolve_callback

typedef void(* ast_dns_resolve_callback) (const struct ast_dns_query *query)

Callback invoked when a query completes.

Parameters

query

The DNS query that was invoked

Definition at line 171 of file dns_core.h.

Function Documentation

ast_dns_query_get_data()

void * ast_dns_query_get_data

(

const struct ast_dns_query *

query

)

Get the user specific data of a DNS query.

Parameters

query

The DNS query

Returns

the user specific data

Note

The reference count of the data is NOT incremented on return

Definition at line 72 of file dns_core.c.

{
    return query->user_data;
}

References ast_dns_query::user_data.

Referenced by async_callback(), dns_query_recurring_resolution_callback(), dns_query_set_callback(), dns_synchronous_resolve_callback(), query_set_cancel(), query_set_resolve(), recurring_cancel(), recurring_resolve(), and resolution_thread().

ast_dns_query_get_name()

const char * ast_dns_query_get_name

(

const struct ast_dns_query *

query

)

Get the name queried in a DNS query.

Parameters

query

The DNS query

Returns

the name queried

Definition at line 57 of file dns_core.c.

{
    return query->name;
}

References ast_dns_query::name.

Referenced by dns_system_resolver_process_query(), dns_system_resolver_resolve(), dns_system_resolver_set_response(), query_set_test(), unbound_resolver_callback(), and unbound_resolver_resolve().

ast_dns_query_get_result()

struct ast_dns_result * ast_dns_query_get_result

(

const struct ast_dns_query *

query

)

Get the result information for a DNS query.

Parameters

query

The DNS query

Returns

the DNS result information

Note

The result is NOT ao2 allocated

Definition at line 77 of file dns_core.c.

{
    return query->result;
}

References ast_dns_query::result.

Referenced by ast_dns_resolve_ipv6_and_ipv4(), AST_TEST_DEFINE(), dns_query_recurring_resolution_callback(), dns_system_resolver_set_response(), and test_results().

ast_dns_query_get_rr_class()

int ast_dns_query_get_rr_class

(

const struct ast_dns_query *

query

)

Get the record resource class of a DNS query.

Parameters

query

The DNS query

Returns

the record resource class

Definition at line 67 of file dns_core.c.

{
    return query->rr_class;
}

References ast_dns_query::rr_class.

Referenced by dns_system_resolver_add_record(), dns_system_resolver_process_query(), query_set_test(), and unbound_resolver_resolve().

ast_dns_query_get_rr_type()

int ast_dns_query_get_rr_type

(

const struct ast_dns_query *

query

)

Get the record resource type of a DNS query.

Parameters

query

The DNS query

Returns

the record resource type

Definition at line 62 of file dns_core.c.

{
    return query->rr_type;
}

References ast_dns_query::rr_type.

Referenced by ast_dns_resolver_completed(), dns_system_resolver_add_record(), dns_system_resolver_process_query(), query_set_test(), and unbound_resolver_resolve().

ast_dns_record_get_data()

const char * ast_dns_record_get_data

(

const struct ast_dns_record *

record

)

Retrieve the raw DNS record.

Parameters

record

The DNS record

Returns

the raw DNS record

Definition at line 160 of file dns_core.c.

{
    return record->data_ptr;
}

References ast_dns_record::data_ptr.

Referenced by ast_dns_resolve_ipv6_and_ipv4(), ast_dns_txt_get_strings(), and test_record().

ast_dns_record_get_data_size()

size_t ast_dns_record_get_data_size

(

const struct ast_dns_record *

record

)

Retrieve the size of the raw DNS record.

Parameters

record

The DNS record

Returns

the size of the raw DNS record

Definition at line 165 of file dns_core.c.

{
    return record->data_len;
}

References ast_dns_record::data_len.

Referenced by ast_dns_resolve_ipv6_and_ipv4(), and ast_dns_txt_get_strings().

ast_dns_record_get_next()

const struct ast_dns_record * ast_dns_record_get_next

(

const struct ast_dns_record *

record

)

Get the next DNS record.

Parameters

record

The current DNS record

Returns

the next DNS record

Definition at line 170 of file dns_core.c.

{
    return AST_LIST_NEXT(record, list);
}

References AST_LIST_NEXT, and ast_dns_record::list.

Referenced by ast_dns_resolve_ipv6_and_ipv4(), ast_dns_result_get_lowest_ttl(), AST_TEST_DEFINE(), and nominal_test().

ast_dns_record_get_rr_class()

int ast_dns_record_get_rr_class

(

const struct ast_dns_record *

record

)

Get the resource record class of a DNS record.

Parameters

record

The DNS record

Returns

the resource record class

Definition at line 150 of file dns_core.c.

{
    return record->rr_class;
}

References ast_dns_record::rr_class.

Referenced by test_record().

ast_dns_record_get_rr_type()

int ast_dns_record_get_rr_type

(

const struct ast_dns_record *

record

)

Get the resource record type of a DNS record.

Parameters

record

The DNS record

Returns

the resource record type

Definition at line 145 of file dns_core.c.

{
    return record->rr_type;
}

References ast_dns_record::rr_type.

Referenced by ast_dns_naptr_get_flags(), ast_dns_naptr_get_order(), ast_dns_naptr_get_preference(), ast_dns_naptr_get_regexp(), ast_dns_naptr_get_replacement(), ast_dns_naptr_get_service(), ast_dns_resolve_ipv6_and_ipv4(), ast_dns_srv_get_host(), ast_dns_srv_get_port(), ast_dns_srv_get_priority(), ast_dns_srv_get_weight(), ast_dns_txt_get_count(), ast_dns_txt_get_strings(), AST_TEST_DEFINE(), and test_record().

ast_dns_record_get_ttl()

int ast_dns_record_get_ttl

(

const struct ast_dns_record *

record

)

Get the TTL of a DNS record.

Parameters

record

The DNS record

Returns

the TTL

Definition at line 155 of file dns_core.c.

{
    return record->ttl;
}

References ast_dns_record::ttl.

Referenced by ast_dns_result_get_lowest_ttl(), and test_record().

ast_dns_resolve()

int ast_dns_resolve	(	const char *	name,
		int	rr_type,
		int	rr_class,
		struct ast_dns_result **	result
	)

Synchronously resolve a DNS query.

Parameters

name	The name of what to resolve
rr_type	Resource record type
rr_class	Resource record class
result	A pointer to hold the DNS result

Return values

0	success - query was completed and result is available
-1	failure

Definition at line 314 of file dns_core.c.

{
    struct dns_synchronous_resolve *synchronous;
    struct ast_dns_query_active *active;
 
    if (ast_strlen_zero(name)) {
        ast_log(LOG_WARNING, "Could not perform synchronous resolution, no name provided\n");
        return -1;
    } else if (rr_type > 65536) {
        ast_log(LOG_WARNING, "Could not perform synchronous resolution of '%s', resource record type '%d' exceeds maximum\n",
            name, rr_type);
        return -1;
    } else if (rr_type < 0) {
        ast_log(LOG_WARNING, "Could not perform synchronous resolution of '%s', invalid resource record type '%d'\n",
            name, rr_type);
        return -1;
    } else if (rr_class > 65536) {
        ast_log(LOG_WARNING, "Could not perform synchronous resolution of '%s', resource record class '%d' exceeds maximum\n",
            name, rr_class);
        return -1;
    } else if (rr_class < 0) {
        ast_log(LOG_WARNING, "Could not perform synchronous resolution of '%s', invalid resource class '%d'\n",
            name, rr_class);
        return -1;
    } else if (!result) {
        ast_log(LOG_WARNING, "Could not perform synchronous resolution of '%s', no result pointer provided for storing results\n",
            name);
        return -1;
    }
 
    synchronous = ao2_alloc_options(sizeof(*synchronous), dns_synchronous_resolve_destroy, AO2_ALLOC_OPT_LOCK_NOLOCK);
    if (!synchronous) {
        return -1;
    }
 
    ast_mutex_init(&synchronous->lock);
    ast_cond_init(&synchronous->cond, NULL);
 
    active = ast_dns_resolve_async(name, rr_type, rr_class, dns_synchronous_resolve_callback, synchronous);
    if (active) {
        /* Wait for resolution to complete */
        ast_mutex_lock(&synchronous->lock);
        while (!synchronous->completed) {
            ast_cond_wait(&synchronous->cond, &synchronous->lock);
        }
        ast_mutex_unlock(&synchronous->lock);
        ao2_ref(active, -1);
    }
 
    *result = synchronous->result;
    ao2_ref(synchronous, -1);
 
    return *result ? 0 : -1;
}

References AO2_ALLOC_OPT_LOCK_NOLOCK, ao2_alloc_options, ao2_ref, ast_cond_init, ast_cond_wait, ast_dns_resolve_async(), ast_log, ast_mutex_init, ast_mutex_lock, ast_mutex_unlock, ast_strlen_zero(), dns_synchronous_resolve::completed, dns_synchronous_resolve::cond, dns_synchronous_resolve_callback(), dns_synchronous_resolve_destroy(), dns_synchronous_resolve::lock, LOG_WARNING, name, NULL, result, and dns_synchronous_resolve::result.

Referenced by AST_TEST_DEFINE(), invalid_record_test(), nominal_test(), and off_nominal_test().

ast_dns_resolve_async()

struct ast_dns_query_active * ast_dns_resolve_async	(	const char *	name,
		int	rr_type,
		int	rr_class,
		ast_dns_resolve_callback	callback,
		void *	data
	)

Asynchronously resolve a DNS query.

Parameters

name	The name of what to resolve
rr_type	Resource record type
rr_class	Resource record class
callback	The callback to invoke upon completion
data	User data to make available on the query

Return values

non-NULL	success - query has been sent for resolution
NULL	failure

Note

The result passed to the callback does not need to be freed

The user data MUST be an ao2 object

This function increments the reference count of the user data, it does NOT steal

The active query must be released upon completion or cancellation using ao2_ref

Definition at line 247 of file dns_core.c.

{
    struct ast_dns_query_active *active;
 
    active = ao2_alloc_options(sizeof(*active), dns_query_active_destroy, AO2_ALLOC_OPT_LOCK_NOLOCK);
    if (!active) {
        return NULL;
    }
 
    active->query = dns_query_alloc(name, rr_type, rr_class, callback, data);
    if (!active->query) {
        ao2_ref(active, -1);
        return NULL;
    }
 
    if (active->query->resolver->resolve(active->query)) {
        ast_log(LOG_ERROR, "Resolver '%s' returned an error when resolving '%s' of class '%d' and type '%d'\n",
            active->query->resolver->name, name, rr_class, rr_type);
        ao2_ref(active, -1);
        return NULL;
    }
 
    return active;
}

References AO2_ALLOC_OPT_LOCK_NOLOCK, ao2_alloc_options, ao2_ref, ast_log, dns_query_active_destroy(), dns_query_alloc(), LOG_ERROR, name, ast_dns_resolver::name, NULL, ast_dns_query_active::query, ast_dns_resolver::resolve, and ast_dns_query::resolver.

Referenced by ast_dns_resolve(), ast_dns_resolve_recurring(), AST_TEST_DEFINE(), and dns_query_recurring_scheduled_callback().

ast_dns_resolve_cancel()

int ast_dns_resolve_cancel

(

struct ast_dns_query_active *

active

)

Cancel an asynchronous DNS resolution.

Parameters

active

The active DNS query returned from ast_dns_resolve_async

Return values

0	success
-1	failure

Note

If successfully cancelled the callback will not be invoked

Definition at line 272 of file dns_core.c.

{
    return active->query->resolver->cancel(active->query);
}

References ast_dns_resolver::cancel, ast_dns_query_active::query, and ast_dns_query::resolver.

Referenced by ast_dns_resolve_recurring_cancel(), and AST_TEST_DEFINE().

ast_dns_resolve_ipv6_and_ipv4()

int ast_dns_resolve_ipv6_and_ipv4	(	struct ast_sockaddr *	address,
		const char *	host,
		const char *	port
	)

Synchronously resolves host to an AAAA or A record.

Since

16.6.0

Parameters

address	A pointer to an ast_sockaddr structure to receive the IPv6 or IPv4 address
host	The hostname to resolve
port	(optional) A port to parse into the final ast_sockaddr structure

Return values

0	success - query was completed and result is available
-1	failure

Note

This function makes parallel queries for both AAAA and A records for the host. The first returned AAAA record (if any) is used and if not found, the first A record is used.

Warning

This function is synchronous and will block until records are returned or an error occurs.

Definition at line 369 of file dns_core.c.

{
    RAII_VAR(struct ast_dns_query_set *, queries, ast_dns_query_set_create(), ao2_cleanup);
    int i;
    int rc;
 
    if (!queries) {
        ast_log(LOG_ERROR, "Couldn't allocate DNS query structure\n");
        return -1;
    }
    rc = ast_dns_query_set_add(queries, host, ns_t_aaaa, ns_c_in);
    if (rc != 0) {
        ast_log(LOG_ERROR, "Couldn't add 'AAAA' DNS query for '%s'\n", host);
        return -1;
    }
    rc = ast_dns_query_set_add(queries, host, ns_t_a, ns_c_in);
    if (rc != 0) {
        ast_log(LOG_ERROR, "Couldn't add 'A' DNS query for '%s'\n", host);
        return -1;
    }
    rc = ast_query_set_resolve(queries);
    if (rc != 0) {
        ast_log(LOG_ERROR, "Query set resolve failure for '%s'\n", host);
        return -1;
    }
    for (i = 0; i < ast_dns_query_set_num_queries(queries); ++i) {
        struct ast_dns_query *query = ast_dns_query_set_get(queries, i);
        struct ast_dns_result *result = ast_dns_query_get_result(query);
        const struct ast_dns_record *record;
        in_port_t in_port = 0;
 
        if (!ast_strlen_zero(port)) {
            in_port = htons(atoi(port));
        }
 
        for (record = ast_dns_result_get_records(result); record; record = ast_dns_record_get_next(record)) {
            size_t data_size = ast_dns_record_get_data_size(record);
            const unsigned char *data = (unsigned char *)ast_dns_record_get_data(record);
            int rr_type = ast_dns_record_get_rr_type(record);
 
            if (rr_type == ns_t_aaaa && data_size == 16) {
                struct sockaddr_in6 sin6 = { 0, };
 
                sin6.sin6_port = in_port;
                memcpy(&sin6.sin6_addr, data, data_size);
                sin6.sin6_family = AF_INET6;
                memcpy(&address->ss, &sin6, sizeof(sin6));
                address->len = sizeof(sin6);
 
                return 0;
            } else if (rr_type == ns_t_a && data_size == 4) {
                struct sockaddr_in sin4 = { 0, };
 
                sin4.sin_port = in_port;
                memcpy(&sin4.sin_addr, data, data_size);
                sin4.sin_family = AF_INET;
                memcpy(&address->ss, &sin4, sizeof(sin4));
                address->len = sizeof(sin4);
 
                return 0;
            } else {
                ast_debug(3, "Unrecognized rr_type '%u' or data_size '%zu' from DNS query for host '%s'\n",
                    rr_type, data_size, host);
                continue;
            }
        }
    }
 
    return -1;
}

References ao2_cleanup, ast_debug, ast_dns_query_get_result(), ast_dns_query_set_add(), ast_dns_query_set_create(), ast_dns_query_set_get(), ast_dns_query_set_num_queries(), ast_dns_record_get_data(), ast_dns_record_get_data_size(), ast_dns_record_get_next(), ast_dns_record_get_rr_type(), ast_dns_result_get_records(), ast_log, ast_query_set_resolve(), ast_strlen_zero(), ast_dns_record::data, LOG_ERROR, RAII_VAR, result, and ast_dns_record::rr_type.

Referenced by unicast_rtp_request().

ast_dns_result_free()

void ast_dns_result_free

(

struct ast_dns_result *

result

)

Free the DNS result information.

Parameters

result

The DNS result

Definition at line 130 of file dns_core.c.

{
    struct ast_dns_record *record;
 
    if (!result) {
        return;
    }
 
    while ((record = AST_LIST_REMOVE_HEAD(&result->records, list))) {
        ast_free(record);
    }
 
    ast_free(result);
}

References ast_free, AST_LIST_REMOVE_HEAD, ast_dns_record::list, and result.

Referenced by ast_dns_resolver_set_result(), AST_TEST_DEFINE(), dns_query_destroy(), invalid_record_test(), nominal_test(), and off_nominal_test().

ast_dns_result_get_answer()

const char * ast_dns_result_get_answer

(

const struct ast_dns_result *

result

)

Get the raw DNS answer from a DNS result.

Parameters

result

The DNS result

Returns

The DNS result

Definition at line 107 of file dns_core.c.

{
    return result->answer;
}

References result.

Referenced by test_results().

ast_dns_result_get_bogus()

unsigned int ast_dns_result_get_bogus

(

const struct ast_dns_result *

result

)

Get whether the result is bogus or not.

Parameters

result

The DNS result

Returns

whether the result is bogus or not

Definition at line 87 of file dns_core.c.

{
    return result->bogus;
}

References result.

Referenced by test_results().

ast_dns_result_get_canonical()

const char * ast_dns_result_get_canonical

(

const struct ast_dns_result *

result

)

Get the canonical name of the result.

Parameters

result

The DNS result

Returns

the canonical name

Definition at line 97 of file dns_core.c.

{
    return result->canonical;
}

References result.

Referenced by test_results().

ast_dns_result_get_lowest_ttl()

int ast_dns_result_get_lowest_ttl

(

const struct ast_dns_result *

result

)

Retrieve the lowest TTL from a result.

Parameters

result

The DNS result

Returns

the lowest TTL

Note

If no records exist this function will return a TTL of 0

Definition at line 112 of file dns_core.c.

{
    int ttl = 0;
    const struct ast_dns_record *record;
 
    if (ast_dns_result_get_rcode(result) == NXDOMAIN) {
        return 0;
    }
 
    for (record = ast_dns_result_get_records(result); record; record = ast_dns_record_get_next(record)) {
        if (!ttl || (ast_dns_record_get_ttl(record) && (ast_dns_record_get_ttl(record) < ttl))) {
            ttl = ast_dns_record_get_ttl(record);
        }
    }
 
    return ttl;
}

References ast_dns_record_get_next(), ast_dns_record_get_ttl(), ast_dns_result_get_rcode(), ast_dns_result_get_records(), result, and ast_dns_record::ttl.

Referenced by dns_query_recurring_resolution_callback().

ast_dns_result_get_rcode()

unsigned int ast_dns_result_get_rcode

(

const struct ast_dns_result *

result

)

Get the error rcode of a DN result.

Parameters

result

The DNS result

Returns

the DNS rcode

Definition at line 92 of file dns_core.c.

{
    return result->rcode;
}

References result.

Referenced by ast_dns_result_get_lowest_ttl(), and test_results().

ast_dns_result_get_records()

const struct ast_dns_record * ast_dns_result_get_records

(

const struct ast_dns_result *

result

)

Get the first record of a DNS Result.

Parameters

result

The DNS result

Returns

first DNS record

Definition at line 102 of file dns_core.c.

{
    return AST_LIST_FIRST(&result->records);
}

References AST_LIST_FIRST, and result.

Referenced by ast_dns_resolve_ipv6_and_ipv4(), ast_dns_result_get_lowest_ttl(), AST_TEST_DEFINE(), invalid_record_test(), nominal_test(), and off_nominal_test().

ast_dns_result_get_secure()

unsigned int ast_dns_result_get_secure

(

const struct ast_dns_result *

result

)

Get whether the result is secure or not.

Parameters

result

The DNS result

Returns

whether the result is secure or not

Definition at line 82 of file dns_core.c.

{
    return result->secure;
}

References result.

Referenced by test_results().