This file contains the interface for DNS handling modules. More...

#include "util/storage/lruhash.h"
#include "util/data/msgreply.h"
#include "util/data/msgparse.h"

Data Structures
struct	errinf_strlist

struct	edns_known_option
	Known edns option. More...

struct	inplace_cb
	Inplace callback list of registered routines to be called. More...

struct	module_env
	Module environment. More...

struct	sock_list
	Linked list of sockaddrs May be allocated such that only 'len' bytes of addr exist for the structure. More...

struct	serve_expired_data
	Struct to hold relevant data for serve expired. More...

struct	module_qstate
	Module state, per query. More...

struct	module_func_block
	Module functionality block. More...

Macros
#define	MAX_MODULE 16
	Maximum number of modules in operation.

#define	MAX_KNOWN_EDNS_OPTS 256
	Maximum number of known edns options.

Typedefs
typedef int	inplace_cb_reply_func_type(struct query_info qinfo, struct module_qstate qstate, struct reply_info rep, int rcode, struct edns_data edns, struct edns_option *opt_list_out, struct comm_reply repinfo, struct regional region, struct timeval start_time, int id, void *callback)
	Inplace callback function called before replying. More...

typedef int	inplace_cb_query_func_type(struct query_info qinfo, uint16_t flags, struct module_qstate qstate, struct sockaddr_storage addr, socklen_t addrlen, uint8_t zone, size_t zonelen, struct regional region, int id, void callback)
	Inplace callback function called before sending the query to a nameserver. More...

typedef int	inplace_cb_edns_back_parsed_func_type(struct module_qstate qstate, int id, void cb_args)
	Inplace callback function called after parsing edns on query reply. More...

typedef int	inplace_cb_query_response_func_type(struct module_qstate qstate, struct dns_msg response, int id, void *cb_args)
	Inplace callback function called after parsing query response. More...

typedef struct dns_msg *	serve_expired_lookup_func_type(struct module_qstate qstate, struct query_info lookup_qinfo)
	Function called when looking for (expired) cached answers during the serve expired logic. More...

Enumerations
enum	inplace_cb_list_type { inplace_cb_reply = 0 , inplace_cb_reply_cache , inplace_cb_reply_local , inplace_cb_reply_servfail , inplace_cb_query , inplace_cb_query_response , inplace_cb_edns_back_parsed , inplace_cb_types_total }

enum	module_ext_state { module_state_initial = 0 , module_wait_reply , module_wait_module , module_restart_next , module_wait_subquery , module_error , module_finished }
	External visible states of the module state machine Modules may also have an internal state. More...

enum	module_ev { module_event_new = 0 , module_event_pass , module_event_reply , module_event_noreply , module_event_capsfail , module_event_moddone , module_event_error }
	Events that happen to modules, that start or wakeup modules. More...

Functions
const char *	strextstate (enum module_ext_state s)
	Debug utility: module external qstate to string. More...

const char *	strmodulevent (enum module_ev e)
	Debug utility: module event to string. More...

void	errinf (struct module_qstate qstate, const char str)
	Append text to the error info for validation. More...

void	errinf_ede (struct module_qstate qstate, const char str, sldns_ede_code reason_bogus)

void	errinf_origin (struct module_qstate qstate, struct sock_list origin)
	Append text to error info: from 1.2.3.4. More...

void	errinf_rrset (struct module_qstate qstate, struct ub_packed_rrset_key rr)
	Append text to error info: for RRset name type class. More...

void	errinf_dname (struct module_qstate qstate, const char str, uint8_t *dname)
	Append text to error info: str dname. More...

char *	errinf_to_str_bogus (struct module_qstate *qstate)
	Create error info in string. More...

sldns_ede_code	errinf_to_reason_bogus (struct module_qstate *qstate)
	Check the sldns_ede_code of the qstate->errinf. More...

char *	errinf_to_str_servfail (struct module_qstate *qstate)
	Create error info in string. More...

char *	errinf_to_str_misc (struct module_qstate *qstate)
	Create error info in string. More...

int	edns_known_options_init (struct module_env *env)
	Initialize the edns known options by allocating the required space. More...

void	edns_known_options_delete (struct module_env *env)
	Free the allocated space for the known edns options. More...

int	edns_register_option (uint16_t opt_code, int bypass_cache_stage, int no_aggregation, struct module_env *env)
	Register a known edns option. More...

int	inplace_cb_register (void cb, enum inplace_cb_list_type type, void cbarg, struct module_env *env, int id)
	Register an inplace callback function. More...

void	inplace_cb_delete (struct module_env *env, enum inplace_cb_list_type type, int id)
	Delete callback for specified type and module id. More...

void	inplace_cb_lists_delete (struct module_env *env)
	Delete all the inplace callback linked lists. More...

struct edns_known_option *	edns_option_is_known (uint16_t opt_code, struct module_env *env)
	Check if an edns option is known. More...

int	edns_bypass_cache_stage (struct edns_option list, struct module_env env)
	Check if an edns option needs to bypass the reply from cache stage. More...

int	unique_mesh_state (struct edns_option list, struct module_env env)
	Check if an unique mesh state is required. More...

void	log_edns_known_options (enum verbosity_value level, struct module_env *env)
	Log the known edns options. More...

void	copy_state_to_super (struct module_qstate qstate, int id, struct module_qstate super)
	Copy state that may have happened in the subquery and is always relevant to the super. More...

Detailed Description

This file contains the interface for DNS handling modules.

The module interface uses the DNS modules as state machines. The state machines are activated in sequence to operate on queries. Once they are done, the reply is passed back. In the usual setup the mesh is the caller of the state machines and once things are done sends replies and invokes result callbacks.

The module provides a number of functions, listed in the module_func_block. The module is inited and destroyed and memory usage queries, for the module as a whole, for entire-module state (such as a cache). And per-query functions are called, operate to move the state machine and cleanup of the per-query state.

Most per-query state should simply be allocated in the query region. This is destroyed at the end of the query.

The module environment contains services and information and caches shared by the modules and the rest of the system. It also contains function pointers for module-specific tasks (like sending queries).

*** Example module calls for a normal query

In this example, the query does not need recursion, all the other data can be found in the cache. This makes the example shorter.

At the start of the program the iterator module is initialised. The iterator module sets up its global state, such as donotquery lists and private address trees.

A query comes in, and a mesh entry is created for it. The mesh starts the resolution process. The validator module is the first in the list of modules, and it is started on this new query. The operate() function is called. The validator decides it needs not do anything yet until there is a result and returns wait_module, that causes the next module in the list to be started.

The next module is the iterator. It is started on the passed query and decides to perform a lookup. For this simple example, the delegation point information is available, and all the iterator wants to do is send a UDP query. The iterator uses env.send_query() to send the query. Then the iterator suspends (returns from the operate call).

When the UDP reply comes back (and on errors and timeouts), the operate function is called for the query, on the iterator module, with the event that there is a reply. The iterator decides that this is enough, the work is done. It returns the value finished from the operate call, which causes the previous module to be started.

The previous module, the validator module, is started with the event that the iterator module is done. The validator decides to validate the query. Once it is done (which could take recursive lookups, but in this example no recursive lookups are needed), it returns from the operate function with finished.

There is no previous module from the validator module, and the mesh takes this to mean that the query is finally done. The mesh invokes callbacks and sends packets to queriers.

If other modules had been waiting (recursively) on the answer to this query, then the mesh will tell them about it. It calls the inform_super routine on all the waiting modules, and once that is done it calls all of them with the operate() call. During inform_super the query that is done still exists and information can be copied from it (but the module should not really re-entry codepoints and services). During the operate call the modules can use stored state to continue operation with the results. (network buffers are used to contain the answer packet during the inform_super phase, but after that the network buffers will be cleared of their contents so that other tasks can be performed).

*** Example module calls for recursion

A module is called in operate, and it decides that it wants to perform recursion. That is, it wants the full state-machine-list to operate on a different query. It calls env.attach_sub() to create a new query state. The routine returns the newly created state, and potentially the module can edit the module-states for the newly created query (i.e. pass along some information, like delegation points). The module then suspends, returns from the operate routine.

The mesh meanwhile will have the newly created query (or queries) on a waiting list, and will call operate() on this query (or queries). It starts again at the start of the module list for them. The query (or queries) continue to operate their state machines, until they are done. When they are done the mesh calls inform_super on the module that wanted the recursion. After that the mesh calls operate() on the module that wanted to do the recursion, and during this phase the module could, for example, decide to create more recursions.

If the module decides it no longer wants the recursive information it can call detach_subs. Those queries will still run to completion, potentially filling the cache with information. Inform_super is not called any more.

The iterator module will fetch items from the cache, so a recursion attempt may complete very quickly if the item is in cache. The calling module has to wait for completion or eventual timeout. A recursive query that times out returns a servfail rcode (servfail is also returned for other errors during the lookup).

Results are passed in the qstate, the rcode member is used to pass errors without requiring memory allocation, so that the code can continue in out-of-memory conditions. If the rcode member is 0 (NOERROR) then the dns_msg entry contains a filled out message. This message may also contain an rcode that is nonzero, but in this case additional information (query, additional) can be passed along.

The rcode and dns_msg are used to pass the result from the the rightmost module towards the leftmost modules and then towards the user.

If you want to avoid recursion-cycles where queries need other queries that need the first one, use detect_cycle() to see if that will happen.

Typedef Documentation

◆ inplace_cb_reply_func_type

typedef int inplace_cb_reply_func_type(struct query_info *qinfo, struct module_qstate *qstate, struct reply_info *rep, int rcode, struct edns_data *edns, struct edns_option **opt_list_out, struct comm_reply *repinfo, struct regional *region, struct timeval *start_time, int id, void *callback)

Inplace callback function called before replying.

Called as func(qinfo, qstate, rep, rcode, edns, opt_list_out, repinfo, region, id, python_callback) Where: qinfo: the query info. qstate: the module state. NULL when calling before the query reaches the mesh states. rep: reply_info. Could be NULL. rcode: the return code. edns: the edns_data of the reply. When qstate is NULL, it is also used as the edns input. opt_list_out: the edns options list for the reply. repinfo: reply information for a communication point. NULL when calling during the mesh states; the same could be found from qstate->mesh_info->reply_list. region: region to store data. id: module id. python_callback: only used for registering a python callback function.

◆ inplace_cb_query_func_type

typedef int inplace_cb_query_func_type(struct query_info *qinfo, uint16_t flags, struct module_qstate *qstate, struct sockaddr_storage *addr, socklen_t addrlen, uint8_t *zone, size_t zonelen, struct regional *region, int id, void *callback)

Inplace callback function called before sending the query to a nameserver.

Called as func(qinfo, flags, qstate, addr, addrlen, zone, zonelen, region, id, python_callback) Where: qinfo: query info. flags: flags of the query. qstate: query state. addr: to which server to send the query. addrlen: length of addr. zone: name of the zone of the delegation point. wireformat dname. This is the delegation point name for which the server is deemed authoritative. zonelen: length of zone. region: region to store data. id: module id. python_callback: only used for registering a python callback function.

◆ inplace_cb_edns_back_parsed_func_type

typedef int inplace_cb_edns_back_parsed_func_type(struct module_qstate *qstate, int id, void *cb_args)

Inplace callback function called after parsing edns on query reply.

Called as func(qstate, id, cb_args) Where: qstate: the query state. id: module id. cb_args: argument passed when registering callback.

◆ inplace_cb_query_response_func_type

typedef int inplace_cb_query_response_func_type(struct module_qstate *qstate, struct dns_msg *response, int id, void *cb_args)

Inplace callback function called after parsing query response.

Called as func(qstate, response, id, cb_args) Where: qstate: the query state. response: query response. id: module id. cb_args: argument passed when registering callback.

◆ serve_expired_lookup_func_type

typedef struct dns_msg* serve_expired_lookup_func_type(struct module_qstate *qstate, struct query_info *lookup_qinfo)

Function called when looking for (expired) cached answers during the serve expired logic.

Called as func(qstate, lookup_qinfo) Where: qstate: the query state. lookup_qinfo: the qinfo to lookup for.

Enumeration Type Documentation

◆ module_ext_state

enum module_ext_state

External visible states of the module state machine Modules may also have an internal state.

Modules are supposed to run to completion or until blocked.

Enumerator
module_state_initial	initial state - new query
module_wait_reply	waiting for reply to outgoing network query
module_wait_module	module is waiting for another module
module_restart_next	module is waiting for another module; that other is restarted
module_wait_subquery	module is waiting for sub-query
module_error	module could not finish the query
module_finished	module is finished with query

◆ module_ev

enum module_ev

Events that happen to modules, that start or wakeup modules.

Enumerator
module_event_new	new query
module_event_pass	query passed by other module
module_event_reply	reply inbound from server
module_event_noreply	no reply, timeout or other error
module_event_capsfail	reply is there, but capitalisation check failed
module_event_moddone	next module is done, and its reply is awaiting you
module_event_error	error

Function Documentation

◆ strextstate()

const char* strextstate ( enum module_ext_state s )

Debug utility: module external qstate to string.

Parameters

s	the state value.

Returns: descriptive string.

References module_error, module_finished, module_restart_next, module_state_initial, module_wait_module, module_wait_reply, and module_wait_subquery.

Referenced by dns64_operate(), get_mesh_status(), ipset_operate(), iter_operate(), mesh_run(), and val_operate().

◆ strmodulevent()

const char* strmodulevent ( enum module_ev e )

Debug utility: module event to string.

Parameters

e	the module event value.

Returns: descriptive string.

References module_event_capsfail, module_event_error, module_event_moddone, module_event_new, module_event_noreply, module_event_pass, and module_event_reply.

Referenced by dns64_operate(), ipset_operate(), iter_operate(), and val_operate().

◆ errinf()

void errinf	(	struct module_qstate *	qstate,
		const char *	str
	)

Append text to the error info for validation.

Parameters

qstate	query state.
str	copied into query region and appended. Failures to allocate are logged.

Referenced by auth_zone_delegpt(), errinf_origin(), errinf_reply(), errinf_rrset(), iter_operate(), prime_stub(), process_response(), processCollectClass(), processFinished(), processInitRequest(), processInitRequest2(), processLastResort(), processQueryTargets(), and validate_suspend_setup_timer().

◆ errinf_origin()

void errinf_origin	(	struct module_qstate *	qstate,
		struct sock_list *	origin
	)

Append text to error info: from 1.2.3.4.

Parameters

qstate	query state.
origin	sock list with origin of trouble. Every element added. If NULL: nothing is added. if 0len element: 'from cache' is added.

References sock_list::addr, addr_to_str(), module_env::cfg, module_qstate::env, errinf(), sock_list::len, config_file::log_servfail, sock_list::next, and config_file::val_log_level.

Referenced by process_ds_response().

◆ errinf_rrset()

void errinf_rrset	(	struct module_qstate *	qstate,
		struct ub_packed_rrset_key *	rr
	)

Append text to error info: for RRset name type class.

Parameters

qstate	query state.
rr	rrset_key.

References module_env::cfg, packed_rrset_key::dname, dname_str(), module_qstate::env, errinf(), LDNS_MAX_DOMAINLEN, config_file::log_servfail, ub_packed_rrset_key::rk, packed_rrset_key::rrset_class, sldns_wire2str_class_buf(), sldns_wire2str_type_buf(), packed_rrset_key::type, and config_file::val_log_level.

◆ errinf_dname()

void errinf_dname	(	struct module_qstate *	qstate,
		const char *	str,
		uint8_t *	dname
	)

Append text to error info: str dname.

Parameters

qstate	query state.
str	explanation string
dname	the dname.

Referenced by process_ds_response(), processDSNSFind(), processInitRequest(), and processLastResort().

◆ errinf_to_str_bogus()

char* errinf_to_str_bogus ( struct module_qstate * qstate )

Create error info in string.

For validation failures.

Parameters

qstate query state.

Returns: string or NULL on malloc failure (already logged). This string is malloced and has to be freed by caller.

References dname_str(), module_qstate::errinf, LDNS_MAX_DOMAINLEN, log_err(), errinf_strlist::next, query_info::qclass, module_qstate::qinfo, query_info::qname, query_info::qtype, sldns_wire2str_class_buf(), sldns_wire2str_type_buf(), and errinf_strlist::str.

◆ errinf_to_reason_bogus()

sldns_ede_code errinf_to_reason_bogus ( struct module_qstate * qstate )

Check the sldns_ede_code of the qstate->errinf.

Parameters

qstate query state.

Returns: the latest explicitly set sldns_ede_code or LDNS_EDE_NONE.

◆ errinf_to_str_servfail()

char* errinf_to_str_servfail ( struct module_qstate * qstate )

Create error info in string.

For other servfails.

Parameters

qstate query state.

Returns: string or NULL on malloc failure (already logged). This string is malloced and has to be freed by caller.

References dname_str(), module_qstate::errinf, LDNS_MAX_DOMAINLEN, log_err(), errinf_strlist::next, query_info::qclass, module_qstate::qinfo, query_info::qname, query_info::qtype, sldns_wire2str_class_buf(), sldns_wire2str_type_buf(), and errinf_strlist::str.

◆ errinf_to_str_misc()

char* errinf_to_str_misc ( struct module_qstate * qstate )

Create error info in string.

For misc failures that are not servfail.

Parameters

qstate query state.

Returns: string or NULL on malloc failure (already logged). This string is malloced and has to be freed by caller.

References module_qstate::errinf, log_err(), errinf_strlist::next, and errinf_strlist::str.

◆ edns_known_options_init()

int edns_known_options_init ( struct module_env * env )

Initialize the edns known options by allocating the required space.

Parameters

env	the module environment.

Returns: false on failure (no memory).

References module_env::edns_known_options, and MAX_KNOWN_EDNS_OPTS.

Referenced by ub_ctx_create_nopipe().

◆ edns_known_options_delete()

void edns_known_options_delete ( struct module_env * env )

Free the allocated space for the known edns options.

Parameters

env	the module environment.

References module_env::edns_known_options.

Referenced by daemon_delete(), ub_ctx_create(), and ub_ctx_create_nopipe().

◆ edns_register_option()

int edns_register_option	(	uint16_t	opt_code,
		int	bypass_cache_stage,
		int	no_aggregation,
		struct module_env *	env
	)

Register a known edns option.

Overwrite the flags if it is already registered. Used before creating workers to register known edns options.

Parameters

opt_code	the edns option code.
bypass_cache_stage	whether the option interacts with the cache.
no_aggregation	whether the option implies more specific aggregation.
env	the module environment.

Returns: true on success, false on failure (registering more options than allowed or trying to register after the environment is copied to the threads.)

Checking if we are full first is faster but it does not provide the option to change the flags when the array is full. It only impacts unbound initialization, leave it for now.

References edns_known_option::bypass_cache_stage, module_env::edns_known_options, log_err(), MAX_KNOWN_EDNS_OPTS, edns_known_option::no_aggregation, edns_known_option::opt_code, and module_env::worker.

◆ inplace_cb_register()

int inplace_cb_register	(	void *	cb,
		enum inplace_cb_list_type	type,
		void *	cbarg,
		struct module_env *	env,
		int	id
	)

Register an inplace callback function.

Parameters

cb	pointer to the callback function.
type	inplace callback type.
cbarg	argument for the callback function, or NULL.
env	the module environment.
id	module id.

Returns: true on success, false on failure (out of memory or trying to register after the environment is copied to the threads.)

References inplace_cb::cb, inplace_cb::id, log_err(), and module_env::worker.

◆ inplace_cb_delete()

void inplace_cb_delete	(	struct module_env *	env,
		enum inplace_cb_list_type	type,
		int	id
	)

Delete callback for specified type and module id.

Parameters

env	the module environment.
type	inplace callback type.
id	module id.

References inplace_cb::id, and inplace_cb::next.

◆ inplace_cb_lists_delete()

void inplace_cb_lists_delete ( struct module_env * env )

Delete all the inplace callback linked lists.

Parameters

env	the module environment.

◆ edns_option_is_known()

struct edns_known_option* edns_option_is_known	(	uint16_t	opt_code,
		struct module_env *	env
	)

Check if an edns option is known.

Parameters

opt_code	the edns option code.
env	the module environment.

Returns: pointer to registered option if the edns option is known, NULL otherwise.

References module_env::edns_known_options, and edns_known_option::opt_code.

◆ edns_bypass_cache_stage()

int edns_bypass_cache_stage	(	struct edns_option *	list,
		struct module_env *	env
	)

Check if an edns option needs to bypass the reply from cache stage.

Parameters

list	the edns options.
env	the module environment.

Returns: true if an edns option needs to bypass the cache stage, false otherwise.

References edns_known_option::bypass_cache_stage, module_env::edns_known_options, edns_option::next, edns_option::opt_code, and edns_known_option::opt_code.

◆ unique_mesh_state()

int unique_mesh_state	(	struct edns_option *	list,
		struct module_env *	env
	)

Check if an unique mesh state is required.

Might be triggered by EDNS option or set for the complete env.

Parameters

list	the edns options.
env	the module environment.

Returns: true if an edns option needs a unique mesh state, false otherwise.

References module_env::edns_known_options, edns_option::next, edns_known_option::no_aggregation, edns_option::opt_code, and edns_known_option::opt_code.

Referenced by mesh_new_callback(), and mesh_new_client().

◆ log_edns_known_options()

void log_edns_known_options	(	enum verbosity_value	level,
		struct module_env *	env
	)

Log the known edns options.

Parameters

level	the desired verbosity level.
env	the module environment.

Referenced by context_finalize().

◆ copy_state_to_super()

void copy_state_to_super	(	struct module_qstate *	qstate,
		int	id,
		struct module_qstate *	super
	)

Copy state that may have happened in the subquery and is always relevant to the super.

Parameters

qstate	query state that finished.
id	module id.
super	the qstate to inform.

Referenced by mesh_walk_supers().

Data Structures

Macros

Typedefs

Enumerations

Functions

Detailed Description

Typedef Documentation

◆ inplace_cb_reply_func_type

◆ inplace_cb_query_func_type

◆ inplace_cb_edns_back_parsed_func_type

◆ inplace_cb_query_response_func_type

◆ serve_expired_lookup_func_type

Enumeration Type Documentation

◆ module_ext_state

◆ module_ev

Function Documentation

◆ strextstate()

◆ strmodulevent()

◆ errinf()

◆ errinf_origin()

◆ errinf_rrset()

◆ errinf_dname()

◆ errinf_to_str_bogus()

◆ errinf_to_reason_bogus()

◆ errinf_to_str_servfail()

◆ errinf_to_str_misc()

◆ edns_known_options_init()

◆ edns_known_options_delete()

◆ edns_register_option()

◆ inplace_cb_register()

◆ inplace_cb_delete()

◆ inplace_cb_lists_delete()

◆ edns_option_is_known()

◆ edns_bypass_cache_stage()

◆ unique_mesh_state()

◆ log_edns_known_options()

◆ copy_state_to_super()