526 lines
20 KiB
C
526 lines
20 KiB
C
/*
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* util/module.h - DNS handling module interface
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*
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* Copyright (c) 2007, NLnet Labs. All rights reserved.
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*
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* This software is open source.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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*
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* Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* Neither the name of the NLNET LABS nor the names of its contributors may
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* be used to endorse or promote products derived from this software without
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* specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
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* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/**
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* \file
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*
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* This file contains the interface for DNS handling modules.
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*
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* The module interface uses the DNS modules as state machines. The
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* state machines are activated in sequence to operate on queries. Once
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* they are done, the reply is passed back. In the usual setup the mesh
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* is the caller of the state machines and once things are done sends replies
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* and invokes result callbacks.
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*
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* The module provides a number of functions, listed in the module_func_block.
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* The module is inited and destroyed and memory usage queries, for the
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* module as a whole, for entire-module state (such as a cache). And per-query
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* functions are called, operate to move the state machine and cleanup of
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* the per-query state.
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*
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* Most per-query state should simply be allocated in the query region.
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* This is destroyed at the end of the query.
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*
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* The module environment contains services and information and caches
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* shared by the modules and the rest of the system. It also contains
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* function pointers for module-specific tasks (like sending queries).
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*
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* *** Example module calls for a normal query
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*
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* In this example, the query does not need recursion, all the other data
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* can be found in the cache. This makes the example shorter.
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*
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* At the start of the program the iterator module is initialised.
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* The iterator module sets up its global state, such as donotquery lists
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* and private address trees.
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*
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* A query comes in, and a mesh entry is created for it. The mesh
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* starts the resolution process. The validator module is the first
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* in the list of modules, and it is started on this new query. The
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* operate() function is called. The validator decides it needs not do
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* anything yet until there is a result and returns wait_module, that
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* causes the next module in the list to be started.
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*
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* The next module is the iterator. It is started on the passed query and
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* decides to perform a lookup. For this simple example, the delegation
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* point information is available, and all the iterator wants to do is
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* send a UDP query. The iterator uses env.send_query() to send the
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* query. Then the iterator suspends (returns from the operate call).
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*
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* When the UDP reply comes back (and on errors and timeouts), the
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* operate function is called for the query, on the iterator module,
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* with the event that there is a reply. The iterator decides that this
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* is enough, the work is done. It returns the value finished from the
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* operate call, which causes the previous module to be started.
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*
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* The previous module, the validator module, is started with the event
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* that the iterator module is done. The validator decides to validate
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* the query. Once it is done (which could take recursive lookups, but
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* in this example no recursive lookups are needed), it returns from the
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* operate function with finished.
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*
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* There is no previous module from the validator module, and the mesh
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* takes this to mean that the query is finally done. The mesh invokes
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* callbacks and sends packets to queriers.
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*
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* If other modules had been waiting (recursively) on the answer to this
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* query, then the mesh will tell them about it. It calls the inform_super
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* routine on all the waiting modules, and once that is done it calls all of
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* them with the operate() call. During inform_super the query that is done
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* still exists and information can be copied from it (but the module should
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* not really re-entry codepoints and services). During the operate call
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* the modules can use stored state to continue operation with the results.
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* (network buffers are used to contain the answer packet during the
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* inform_super phase, but after that the network buffers will be cleared
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* of their contents so that other tasks can be performed).
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*
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* *** Example module calls for recursion
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*
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* A module is called in operate, and it decides that it wants to perform
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* recursion. That is, it wants the full state-machine-list to operate on
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* a different query. It calls env.attach_sub() to create a new query state.
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* The routine returns the newly created state, and potentially the module
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* can edit the module-states for the newly created query (i.e. pass along
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* some information, like delegation points). The module then suspends,
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* returns from the operate routine.
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*
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* The mesh meanwhile will have the newly created query (or queries) on
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* a waiting list, and will call operate() on this query (or queries).
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* It starts again at the start of the module list for them. The query
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* (or queries) continue to operate their state machines, until they are
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* done. When they are done the mesh calls inform_super on the module that
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* wanted the recursion. After that the mesh calls operate() on the module
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* that wanted to do the recursion, and during this phase the module could,
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* for example, decide to create more recursions.
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*
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* If the module decides it no longer wants the recursive information
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* it can call detach_subs. Those queries will still run to completion,
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* potentially filling the cache with information. Inform_super is not
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* called any more.
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*
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* The iterator module will fetch items from the cache, so a recursion
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* attempt may complete very quickly if the item is in cache. The calling
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* module has to wait for completion or eventual timeout. A recursive query
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* that times out returns a servfail rcode (servfail is also returned for
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* other errors during the lookup).
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*
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* Results are passed in the qstate, the rcode member is used to pass
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* errors without requiring memory allocation, so that the code can continue
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* in out-of-memory conditions. If the rcode member is 0 (NOERROR) then
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* the dns_msg entry contains a filled out message. This message may
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* also contain an rcode that is nonzero, but in this case additional
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* information (query, additional) can be passed along.
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*
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* The rcode and dns_msg are used to pass the result from the the rightmost
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* module towards the leftmost modules and then towards the user.
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*
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* If you want to avoid recursion-cycles where queries need other queries
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* that need the first one, use detect_cycle() to see if that will happen.
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*
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*/
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#ifndef UTIL_MODULE_H
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#define UTIL_MODULE_H
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#include "util/storage/lruhash.h"
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#include "util/data/msgreply.h"
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#include "util/data/msgparse.h"
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struct sldns_buffer;
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struct alloc_cache;
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struct rrset_cache;
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struct key_cache;
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struct config_file;
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struct slabhash;
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struct query_info;
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struct edns_data;
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struct regional;
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struct worker;
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struct module_qstate;
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struct ub_randstate;
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struct mesh_area;
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struct mesh_state;
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struct val_anchors;
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struct val_neg_cache;
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struct iter_forwards;
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struct iter_hints;
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/** Maximum number of modules in operation */
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#define MAX_MODULE 5
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/**
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* Module environment.
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* Services and data provided to the module.
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*/
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struct module_env {
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/* --- data --- */
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/** config file with config options */
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struct config_file* cfg;
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/** shared message cache */
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struct slabhash* msg_cache;
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/** shared rrset cache */
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struct rrset_cache* rrset_cache;
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/** shared infrastructure cache (edns, lameness) */
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struct infra_cache* infra_cache;
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/** shared key cache */
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struct key_cache* key_cache;
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/* --- services --- */
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/**
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* Send serviced DNS query to server. UDP/TCP and EDNS is handled.
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* operate() should return with wait_reply. Later on a callback
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* will cause operate() to be called with event timeout or reply.
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* The time until a timeout is calculated from roundtrip timing,
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* several UDP retries are attempted.
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* @param qname: query name. (host order)
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* @param qnamelen: length in bytes of qname, including trailing 0.
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* @param qtype: query type. (host order)
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* @param qclass: query class. (host order)
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* @param flags: host order flags word, with opcode and CD bit.
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* @param dnssec: if set, EDNS record will have bits set.
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* If EDNS_DO bit is set, DO bit is set in EDNS records.
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* If BIT_CD is set, CD bit is set in queries with EDNS records.
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* @param want_dnssec: if set, the validator wants DNSSEC. Without
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* EDNS, the answer is likely to be useless for this domain.
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* @param nocaps: do not use caps_for_id, use the qname as given.
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* (ignored if caps_for_id is disabled).
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* @param opt_list: set these EDNS options on the outgoing packet.
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* or NULL if none (the list is deep-copied).
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* @param addr: where to.
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* @param addrlen: length of addr.
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* @param zone: delegation point name.
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* @param zonelen: length of zone name.
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* @param q: wich query state to reactivate upon return.
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* @return: false on failure (memory or socket related). no query was
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* sent. Or returns an outbound entry with qsent and qstate set.
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* This outbound_entry will be used on later module invocations
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* that involve this query (timeout, error or reply).
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*/
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struct outbound_entry* (*send_query)(uint8_t* qname, size_t qnamelen,
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uint16_t qtype, uint16_t qclass, uint16_t flags, int dnssec,
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int want_dnssec, int nocaps, struct edns_option* opt_list,
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struct sockaddr_storage* addr, socklen_t addrlen,
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uint8_t* zone, size_t zonelen, struct module_qstate* q);
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/**
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* Detach-subqueries.
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* Remove all sub-query references from this query state.
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* Keeps super-references of those sub-queries correct.
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* Updates stat items in mesh_area structure.
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* @param qstate: used to find mesh state.
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*/
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void (*detach_subs)(struct module_qstate* qstate);
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/**
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* Attach subquery.
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* Creates it if it does not exist already.
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* Keeps sub and super references correct.
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* Updates stat items in mesh_area structure.
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* Pass if it is priming query or not.
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* return:
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* o if error (malloc) happened.
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* o need to initialise the new state (module init; it is a new state).
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* so that the next run of the query with this module is successful.
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* o no init needed, attachment successful.
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*
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* @param qstate: the state to find mesh state, and that wants to
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* receive the results from the new subquery.
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* @param qinfo: what to query for (copied).
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* @param qflags: what flags to use (RD, CD flag or not).
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* @param prime: if it is a (stub) priming query.
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* @param valrec: validation lookup recursion, does not need validation
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* @param newq: If the new subquery needs initialisation, it is
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* returned, otherwise NULL is returned.
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* @return: false on error, true if success (and init may be needed).
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*/
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int (*attach_sub)(struct module_qstate* qstate,
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struct query_info* qinfo, uint16_t qflags, int prime,
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int valrec, struct module_qstate** newq);
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/**
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* Kill newly attached sub. If attach_sub returns newq for
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* initialisation, but that fails, then this routine will cleanup and
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* delete the fresly created sub.
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* @param newq: the new subquery that is no longer needed.
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* It is removed.
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*/
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void (*kill_sub)(struct module_qstate* newq);
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/**
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* Detect if adding a dependency for qstate on name,type,class will
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* create a dependency cycle.
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* @param qstate: given mesh querystate.
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* @param qinfo: query info for dependency.
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* @param flags: query flags of dependency, RD/CD flags.
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* @param prime: if dependency is a priming query or not.
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* @param valrec: validation lookup recursion, does not need validation
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* @return true if the name,type,class exists and the given
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* qstate mesh exists as a dependency of that name. Thus
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* if qstate becomes dependent on name,type,class then a
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* cycle is created.
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*/
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int (*detect_cycle)(struct module_qstate* qstate,
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struct query_info* qinfo, uint16_t flags, int prime,
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int valrec);
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/** region for temporary usage. May be cleared after operate() call. */
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struct regional* scratch;
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/** buffer for temporary usage. May be cleared after operate() call. */
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struct sldns_buffer* scratch_buffer;
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/** internal data for daemon - worker thread. */
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struct worker* worker;
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/** mesh area with query state dependencies */
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struct mesh_area* mesh;
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/** allocation service */
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struct alloc_cache* alloc;
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/** random table to generate random numbers */
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struct ub_randstate* rnd;
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/** time in seconds, converted to integer */
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time_t* now;
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/** time in microseconds. Relatively recent. */
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struct timeval* now_tv;
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/** is validation required for messages, controls client-facing
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* validation status (AD bits) and servfails */
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int need_to_validate;
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/** trusted key storage; these are the configured keys, if not NULL,
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* otherwise configured by validator. These are the trust anchors,
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* and are not primed and ready for validation, but on the bright
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* side, they are read only memory, thus no locks and fast. */
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struct val_anchors* anchors;
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/** negative cache, configured by the validator. if not NULL,
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* contains NSEC record lookup trees. */
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struct val_neg_cache* neg_cache;
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/** the 5011-probe timer (if any) */
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struct comm_timer* probe_timer;
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/** Mapping of forwarding zones to targets.
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* iterator forwarder information. per-thread, created by worker */
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struct iter_forwards* fwds;
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/**
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* iterator forwarder information. per-thread, created by worker.
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* The hints -- these aren't stored in the cache because they don't
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* expire. The hints are always used to "prime" the cache. Note
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* that both root hints and stub zone "hints" are stored in this
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* data structure.
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*/
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struct iter_hints* hints;
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/** module specific data. indexed by module id. */
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void* modinfo[MAX_MODULE];
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};
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/**
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* External visible states of the module state machine
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* Modules may also have an internal state.
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* Modules are supposed to run to completion or until blocked.
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*/
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enum module_ext_state {
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/** initial state - new query */
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module_state_initial = 0,
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/** waiting for reply to outgoing network query */
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module_wait_reply,
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/** module is waiting for another module */
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module_wait_module,
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/** module is waiting for another module; that other is restarted */
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module_restart_next,
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/** module is waiting for sub-query */
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module_wait_subquery,
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/** module could not finish the query */
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module_error,
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/** module is finished with query */
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module_finished
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};
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/**
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* Events that happen to modules, that start or wakeup modules.
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*/
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enum module_ev {
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/** new query */
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module_event_new = 0,
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/** query passed by other module */
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module_event_pass,
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/** reply inbound from server */
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module_event_reply,
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/** no reply, timeout or other error */
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module_event_noreply,
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/** reply is there, but capitalisation check failed */
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module_event_capsfail,
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/** next module is done, and its reply is awaiting you */
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module_event_moddone,
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/** error */
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module_event_error
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};
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/**
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* Linked list of sockaddrs
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* May be allocated such that only 'len' bytes of addr exist for the structure.
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*/
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struct sock_list {
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/** next in list */
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struct sock_list* next;
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/** length of addr */
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socklen_t len;
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/** sockaddr */
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struct sockaddr_storage addr;
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};
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/**
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* Module state, per query.
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*/
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struct module_qstate {
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/** which query is being answered: name, type, class */
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struct query_info qinfo;
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/** flags uint16 from query */
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uint16_t query_flags;
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/** if this is a (stub or root) priming query (with hints) */
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int is_priming;
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/** if this is a validation recursion query that does not get
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* validation itself */
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int is_valrec;
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/** comm_reply contains server replies */
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struct comm_reply* reply;
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/** the reply message, with message for client and calling module */
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struct dns_msg* return_msg;
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/** the rcode, in case of error, instead of a reply message */
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int return_rcode;
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/** origin of the reply (can be NULL from cache, list for cnames) */
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struct sock_list* reply_origin;
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/** IP blacklist for queries */
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struct sock_list* blacklist;
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/** region for this query. Cleared when query process finishes. */
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struct regional* region;
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/** failure reason information if val-log-level is high */
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struct config_strlist* errinf;
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/** which module is executing */
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int curmod;
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/** module states */
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enum module_ext_state ext_state[MAX_MODULE];
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/** module specific data for query. indexed by module id. */
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void* minfo[MAX_MODULE];
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/** environment for this query */
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struct module_env* env;
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/** mesh related information for this query */
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struct mesh_state* mesh_info;
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/** how many seconds before expiry is this prefetched (0 if not) */
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time_t prefetch_leeway;
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};
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/**
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* Module functionality block
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*/
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struct module_func_block {
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/** text string name of module */
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const char* name;
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/**
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* init the module. Called once for the global state.
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* This is the place to apply settings from the config file.
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* @param env: module environment.
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* @param id: module id number.
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* return: 0 on error
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*/
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int (*init)(struct module_env* env, int id);
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/**
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* de-init, delete, the module. Called once for the global state.
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* @param env: module environment.
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* @param id: module id number.
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*/
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void (*deinit)(struct module_env* env, int id);
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/**
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* accept a new query, or work further on existing query.
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* Changes the qstate->ext_state to be correct on exit.
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* @param ev: event that causes the module state machine to
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* (re-)activate.
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* @param qstate: the query state.
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* Note that this method is not allowed to change the
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* query state 'identity', that is query info, qflags,
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* and priming status.
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* Attach a subquery to get results to a different query.
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* @param id: module id number that operate() is called on.
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* @param outbound: if not NULL this event is due to the reply/timeout
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* or error on this outbound query.
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* @return: if at exit the ext_state is:
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* o wait_module: next module is started. (with pass event).
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* o error or finished: previous module is resumed.
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* o otherwise it waits until that event happens (assumes
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* the service routine to make subrequest or send message
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|
* have been called.
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|
*/
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|
void (*operate)(struct module_qstate* qstate, enum module_ev event,
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|
int id, struct outbound_entry* outbound);
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|
|
|
/**
|
|
* inform super querystate about the results from this subquerystate.
|
|
* Is called when the querystate is finished. The method invoked is
|
|
* the one from the current module active in the super querystate.
|
|
* @param qstate: the query state that is finished.
|
|
* Examine return_rcode and return_reply in the qstate.
|
|
* @param id: module id for this module.
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|
* This coincides with the current module for the super qstate.
|
|
* @param super: the super querystate that needs to be informed.
|
|
*/
|
|
void (*inform_super)(struct module_qstate* qstate, int id,
|
|
struct module_qstate* super);
|
|
|
|
/**
|
|
* clear module specific data
|
|
*/
|
|
void (*clear)(struct module_qstate* qstate, int id);
|
|
|
|
/**
|
|
* How much memory is the module specific data using.
|
|
* @param env: module environment.
|
|
* @param id: the module id.
|
|
* @return the number of bytes that are alloced.
|
|
*/
|
|
size_t (*get_mem)(struct module_env* env, int id);
|
|
};
|
|
|
|
/**
|
|
* Debug utility: module external qstate to string
|
|
* @param s: the state value.
|
|
* @return descriptive string.
|
|
*/
|
|
const char* strextstate(enum module_ext_state s);
|
|
|
|
/**
|
|
* Debug utility: module event to string
|
|
* @param e: the module event value.
|
|
* @return descriptive string.
|
|
*/
|
|
const char* strmodulevent(enum module_ev e);
|
|
|
|
#endif /* UTIL_MODULE_H */
|