/* * iterator/iterator.c - iterative resolver DNS query response module * * Copyright (c) 2007, NLnet Labs. All rights reserved. * * This software is open source. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * Redistributions of source code must retain the above copyright notice, * this list of conditions and the following disclaimer. * * Redistributions in binary form must reproduce the above copyright notice, * this list of conditions and the following disclaimer in the documentation * and/or other materials provided with the distribution. * * Neither the name of the NLNET LABS nor the names of its contributors may * be used to endorse or promote products derived from this software without * specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ /** * \file * * This file contains a module that performs recusive iterative DNS query * processing. */ #include "config.h" #include "iterator/iterator.h" #include "iterator/iter_utils.h" #include "iterator/iter_hints.h" #include "iterator/iter_delegpt.h" #include "iterator/iter_resptype.h" #include "iterator/iter_scrub.h" #include "services/cache/dns.h" #include "util/module.h" #include "util/netevent.h" #include "util/net_help.h" #include "util/region-allocator.h" #include "util/data/dname.h" #include "util/data/msgencode.h" /** iterator init */ static int iter_init(struct module_env* env, int id) { struct iter_env* iter_env = (struct iter_env*)calloc(1, sizeof(struct iter_env)); if(!iter_env) { log_err("malloc failure"); return 0; } env->modinfo[id] = (void*)iter_env; if(!iter_apply_cfg(iter_env, env->cfg)) { log_err("iterator: could not apply configuration settings."); return 0; } return 1; } /** iterator deinit */ static void iter_deinit(struct module_env* env, int id) { struct iter_env* iter_env; if(!env || !env->modinfo) return; iter_env = (struct iter_env*)env->modinfo[id]; free(iter_env->target_fetch_policy); hints_delete(iter_env->hints); if(iter_env) free(iter_env); } /** new query for iterator */ static int iter_new(struct module_qstate* qstate, int id) { struct iter_qstate* iq = (struct iter_qstate*)region_alloc( qstate->region, sizeof(struct iter_qstate)); qstate->minfo[id] = iq; if(!iq) return 0; memset(iq, 0, sizeof(*iq)); iq->state = INIT_REQUEST_STATE; iq->final_state = FINISHED_STATE; iq->prepend_list = NULL; iq->prepend_last = NULL; iq->dp = NULL; iq->num_target_queries = -1; /* default our targetQueries counter. */ iq->num_current_queries = 0; iq->query_restart_count = 0; iq->referral_count = 0; iq->priming_stub = 0; iq->orig_qflags = qstate->query_flags; /* remove all weird bits from the query flags */ qstate->query_flags &= (BIT_RD | BIT_CD); outbound_list_init(&iq->outlist); return 1; } /** new query for iterator in forward mode */ static int fwd_new(struct module_qstate* qstate, int id) { struct iter_qstate* iq = (struct iter_qstate*)region_alloc( qstate->region, sizeof(struct iter_qstate)); struct module_env* env = qstate->env; struct iter_env* ie = (struct iter_env*)env->modinfo[id]; struct outbound_entry* e; uint16_t flags = 0; /* opcode=query, no flags */ int dnssec = 1; /* always get dnssec info */ qstate->minfo[id] = iq; if(!iq) return 0; memset(iq, 0, sizeof(*iq)); outbound_list_init(&iq->outlist); e = (*env->send_query)(qstate->qinfo.qname, qstate->qinfo.qname_len, qstate->qinfo.qtype, qstate->qinfo.qclass, flags, dnssec, &ie->fwd_addr, ie->fwd_addrlen, qstate); if(!e) return 0; outbound_list_insert(&iq->outlist, e); qstate->ext_state[id] = module_wait_reply; return 1; } /** iterator handle reply from authoritative server */ static int iter_handlereply(struct module_qstate* qstate, int id, struct outbound_entry* ATTR_UNUSED(outbound)) { struct module_env* env = qstate->env; uint16_t us = qstate->edns.udp_size; struct query_info reply_qinfo; struct reply_info* reply_msg; struct edns_data reply_edns; int r; if((r=reply_info_parse(qstate->reply->c->buffer, env->alloc, &reply_qinfo, &reply_msg, qstate->scratch, &reply_edns))!=0) return 0; qstate->edns.edns_version = EDNS_ADVERTISED_VERSION; qstate->edns.udp_size = EDNS_ADVERTISED_SIZE; qstate->edns.ext_rcode = 0; qstate->edns.bits &= EDNS_DO; if(!reply_info_answer_encode(&reply_qinfo, reply_msg, 0, qstate->query_flags, qstate->buf, 0, 0, qstate->scratch, us, &qstate->edns)) return 0; dns_cache_store_msg(qstate->env, &reply_qinfo, qstate->query_hash, reply_msg); qstate->ext_state[id] = module_finished; return 1; } /** perform forwarder functionality */ static void perform_forward(struct module_qstate* qstate, enum module_ev event, int id, struct outbound_entry* outbound) { verbose(VERB_ALGO, "iterator: forwarding"); if(event == module_event_new) { if(!fwd_new(qstate, id)) qstate->ext_state[id] = module_error; return; } /* it must be a query reply */ if(!outbound) { verbose(VERB_ALGO, "query reply was not serviced"); qstate->ext_state[id] = module_error; return; } if(event == module_event_timeout || event == module_event_error) { qstate->ext_state[id] = module_error; return; } if(event == module_event_reply) { if(!iter_handlereply(qstate, id, outbound)) qstate->ext_state[id] = module_error; return; } log_err("bad event for iterator[forwarding]"); qstate->ext_state[id] = module_error; } /** * Transition to the next state. This can be used to advance a currently * processing event. It cannot be used to reactivate a forEvent. * * @param qstate: query state * @param iq: iterator query state * @param nextstate The state to transition to. * @return true. This is so this can be called as the return value for the * actual process*State() methods. (Transitioning to the next state * implies further processing). */ static int next_state(struct module_qstate* qstate, struct iter_qstate* iq, enum iter_state nextstate) { /* If transitioning to a "response" state, make sure that there is a * response */ if(iter_state_is_responsestate(nextstate)) { if(qstate->reply == NULL || iq->response == NULL) { log_err("transitioning to response state sans " "response."); } } iq->state = nextstate; return 1; } /** * Transition an event to its final state. Final states always either return * a result up the module chain, or reactivate a dependent event. Which * final state to transtion to is set in the module state for the event when * it was created, and depends on the original purpose of the event. * * The response is stored in the qstate->buf buffer. * * @param qstate: query state * @param iq: iterator query state * @return false. This is so this method can be used as the return value for * the processState methods. (Transitioning to the final state */ static int final_state(struct module_qstate* qstate, struct iter_qstate* iq) { return next_state(qstate, iq, iq->final_state); } /** * Return an error to the client */ static int error_response(struct module_qstate* qstate, struct iter_qstate* iq, int rcode) { log_info("err response %s", ldns_lookup_by_id(ldns_rcodes, rcode)? ldns_lookup_by_id(ldns_rcodes, rcode)->name:"??"); qinfo_query_encode(qstate->buf, &qstate->qinfo); LDNS_RCODE_SET(ldns_buffer_begin(qstate->buf), rcode); LDNS_QR_SET(ldns_buffer_begin(qstate->buf)); return final_state(qstate, iq); } #if 0 /** prepend the prepend list in the answer section of dns_msg */ static int iter_prepend(struct iter_qstate* iq, struct dns_msg* msg, struct region* region) { struct packed_rrset_list* p; struct ub_packed_rrset_key** sets; size_t num = 0; for(p = iq->prepend_list; p; p = p->next) num++; if(num == 0) return 1; sets = region_alloc(region, (num+msg->rep->rrset_count) * sizeof(struct ub_packed_rrset_key*)); if(!sets) return 0; memcpy(sets+num, msg->rep->rrsets, msg->rep->rrset_count * sizeof(struct ub_packed_rrset_key*)); num = 0; for(p = iq->prepend_list; p; p = p->next) { sets[num] = (struct ub_packed_rrset_key*)region_alloc(region, sizeof(struct ub_packed_rrset_key)); if(!sets[num]) return 0; sets[num]->rk = *p->rrset.k; sets[num]->entry.data = p->rrset.d; num++; } msg->rep->rrsets = sets; return 1; } /** * Encode response message for iterator responses. Into response buffer. * On error an error message is encoded. * @param qstate: query state. With qinfo information. * @param iq: iterator query state. With qinfo original and prepend list. * @param msg: answer message. */ static void iter_encode_respmsg(struct module_qstate* qstate, struct iter_qstate* iq, struct dns_msg* msg) { struct query_info qinf = qstate->qinfo; uint32_t now = time(NULL); struct edns_data edns; if(iq->orig_qname) { qinf.qname = iq->orig_qname; qinf.qname_len = iq->orig_qnamelen; } if(iq->prepend_list) { if(!iter_prepend(iq, msg, qstate->region)) { error_response(qstate, iq, LDNS_RCODE_SERVFAIL); return; } } edns.edns_present = qstate->edns.edns_present; edns.edns_version = EDNS_ADVERTISED_VERSION; edns.udp_size = EDNS_ADVERTISED_SIZE; edns.ext_rcode = 0; edns.bits = qstate->edns.bits & EDNS_DO; if(!reply_info_answer_encode(&qinf, msg->rep, 0, iq->orig_qflags, qstate->buf, now, 1, qstate->scratch, qstate->edns.udp_size, &edns)) { /* encode servfail */ error_response(qstate, iq, LDNS_RCODE_SERVFAIL); return; } } #endif /** * Add rrset to prepend list * @param qstate: query state. * @param iq: iterator query state. * @param rrset: rrset to add. * @return false on failure (malloc). */ static int iter_add_prepend(struct module_qstate* qstate, struct iter_qstate* iq, struct ub_packed_rrset_key* rrset) { struct iter_prep_list* p = (struct iter_prep_list*)region_alloc( qstate->region, sizeof(struct iter_prep_list)); if(!p) return 0; p->rrset = rrset; p->next = NULL; /* add at end */ if(iq->prepend_last) iq->prepend_last->next = p; else iq->prepend_list = p; iq->prepend_last = p; return 1; } /** * Given a CNAME response (defined as a response containing a CNAME or DNAME * that does not answer the request), process the response, modifying the * state as necessary. This follows the CNAME/DNAME chain and returns the * final query name. * * sets the new query name, after following the CNAME/DNAME chain. * @param qstate: query state. * @param iq: iterator query state. * @param msg: the response. * @param mname: returned target new query name. * @param mname_len: length of mname. * @return false on (malloc) error. */ static int handle_cname_response(struct module_qstate* qstate, struct iter_qstate* iq, struct dns_msg* msg, uint8_t** mname, size_t* mname_len) { size_t i; /* Start with the (current) qname. */ *mname = qstate->qinfo.qname; *mname_len = qstate->qinfo.qname_len; /* Iterate over the ANSWER rrsets in order, looking for CNAMEs and * DNAMES. */ for(i=0; irep->an_numrrsets; i++) { struct ub_packed_rrset_key* r = msg->rep->rrsets[i]; /* If there is a (relevant) DNAME, add it to the list. * We always expect there to be CNAME that was generated * by this DNAME following, so we don't process the DNAME * directly. */ if(ntohs(r->rk.type) == LDNS_RR_TYPE_DNAME && dname_strict_subdomain_c(*mname, r->rk.dname)) { if(!iter_add_prepend(qstate, iq, r)) return 0; continue; } if(ntohs(r->rk.type) == LDNS_RR_TYPE_CNAME && query_dname_compare(*mname, r->rk.dname) == 0) { /* Add this relevant CNAME rrset to the prepend list.*/ if(!iter_add_prepend(qstate, iq, r)) return 0; get_cname_target(r, mname, mname_len); } /* Other rrsets in the section are ignored. */ } return 1; } /** * Generate a subrequest. * Generate a local request event. Local events are tied to this module, and * have a correponding (first tier) event that is waiting for this event to * resolve to continue. * * @param qname The query name for this request. * @param qnamelen length of qname * @param qtype The query type for this request. * @param qclass The query class for this request. * @param qstate The event that is generating this event. * @param id: module id. * @param initial_state The initial response state (normally this * is QUERY_RESP_STATE, unless it is known that the request won't * need iterative processing * @param final_state The final state for the response to this * request. * @return generated subquerystate, or NULL on error (malloc). */ static struct module_qstate* generate_sub_request(uint8_t* qname, size_t qnamelen, uint16_t qtype, uint16_t qclass, struct module_qstate* qstate, int id, enum iter_state initial_state, enum iter_state final_state) { struct module_qstate* subq = (struct module_qstate*)malloc( sizeof(struct module_qstate)); struct iter_qstate* subiq; if(!subq) return NULL; memset(subq, 0, sizeof(*subq)); subq->qinfo.qname = memdup(qname, qnamelen); if(!subq->qinfo.qname) { free(subq); return NULL; } subq->qinfo.qname_len = qnamelen; subq->qinfo.qtype = qtype; subq->qinfo.qclass = qclass; subq->query_hash = query_info_hash(&subq->qinfo); subq->query_flags = 0; /* OPCODE QUERY, no flags */ subq->edns.udp_size = 65535; subq->buf = qstate->buf; subq->scratch = qstate->scratch; subq->region = region_create(malloc, free); if(!subq->region) { free(subq->qinfo.qname); free(subq); return NULL; } subq->curmod = id; subq->ext_state[id] = module_state_initial; subq->minfo[id] = region_alloc(subq->region, sizeof(struct iter_qstate)); if(!subq->minfo[id]) { region_destroy(subq->region); free(subq->qinfo.qname); free(subq); return NULL; } subq->env = qstate->env; subq->work_info = qstate->work_info; subq->parent = qstate; subq->subquery_next = qstate->subquery_first; qstate->subquery_first = subq; subiq = (struct iter_qstate*)subq->minfo[id]; memset(subiq, 0, sizeof(*subiq)); subiq->num_target_queries = -1; /* default our targetQueries counter. */ outbound_list_init(&subiq->outlist); subiq->state = initial_state; subiq->final_state = final_state; /* RD should be set only when sending the query back through the INIT * state. */ if(initial_state == INIT_REQUEST_STATE) subq->query_flags |= BIT_RD; /* We set the CD flag so we can send this through the "head" of * the resolution chain, which might have a validator. We are * uninterested in validating things not on the direct resolution * path. */ subq->query_flags |= BIT_CD; subiq->orig_qflags = subq->query_flags; return subq; } /** * Generate and send a root priming request. * @param qstate: the qtstate that triggered the need to prime. * @param ie: iterator global state. * @param id: module id. * @param qclass: the class to prime. */ static int prime_root(struct module_qstate* qstate, struct iter_env* ie, int id, uint16_t qclass) { struct delegpt* dp; struct module_qstate* subq; struct iter_qstate* subiq; verbose(VERB_ALGO, "priming . NS %s", ldns_lookup_by_id(ldns_rr_classes, (int)qclass)? ldns_lookup_by_id(ldns_rr_classes, (int)qclass)->name:"??"); dp = hints_lookup_root(ie->hints, qclass); if(!dp) { verbose(VERB_ALGO, "Cannot prime due to lack of hints"); return 0; } /* Priming requests start at the QUERYTARGETS state, skipping * the normal INIT state logic (which would cause an infloop). */ subq = generate_sub_request((uint8_t*)"\000", 1, LDNS_RR_TYPE_NS, qclass, qstate, id, QUERYTARGETS_STATE, PRIME_RESP_STATE); if(!subq) { log_err("out of memory priming root"); return 0; } subiq = (struct iter_qstate*)subq->minfo[id]; /* Set the initial delegation point to the hint. */ subiq->dp = dp; /* suppress any target queries. */ subiq->num_target_queries = 0; /* this module stops, our submodule starts, and does the query. */ qstate->ext_state[id] = module_wait_subquery; return 1; } /** * Generate and process a stub priming request. This method tests for the * need to prime a stub zone, so it is safe to call for every request. * * @param qstate: the qtstate that triggered the need to prime. * @param iq: iterator query state. * @param ie: iterator global state. * @param id: module id. * @param qname: request name. * @param qclass: the class to prime. * @return true if a priming subrequest was made, false if not. The will only * issue a priming request if it detects an unprimed stub. */ static int prime_stub(struct module_qstate* qstate, struct iter_qstate* iq, struct iter_env* ie, int id, uint8_t* qname, uint16_t qclass) { /* Lookup the stub hint. This will return null if the stub doesn't * need to be re-primed. */ struct delegpt* stub_dp = hints_lookup_stub(ie->hints, qname, qclass, iq->dp); struct module_qstate* subq; struct iter_qstate* subiq; /* The stub (if there is one) does not need priming. */ if(!stub_dp) return 0; /* Otherwise, we need to (re)prime the stub. */ log_nametypeclass("priming stub", stub_dp->name, LDNS_RR_TYPE_NS, qclass); /* Stub priming events start at the QUERYTARGETS state to avoid the * redundant INIT state processing. */ subq = generate_sub_request(stub_dp->name, stub_dp->namelen, LDNS_RR_TYPE_NS, qclass, qstate, id, QUERYTARGETS_STATE, PRIME_RESP_STATE); if(!subq) { log_err("out of memory priming stub"); qstate->ext_state[id] = module_error; return 1; /* return 1 to make module stop, with error */ } subiq = (struct iter_qstate*)subq->minfo[id]; /* Set the initial delegation point to the hint. */ subiq->dp = stub_dp; /* suppress any target queries -- although there wouldn't be anyway, * since stub hints never have missing targets.*/ subiq->num_target_queries = 0; subiq->priming_stub = 1; /* this module stops, our submodule starts, and does the query. */ qstate->ext_state[id] = module_wait_subquery; return 1; } /** * Process the initial part of the request handling. This state roughly * corresponds to resolver algorithms steps 1 (find answer in cache) and 2 * (find the best servers to ask). * * Note that all requests start here, and query restarts revisit this state. * * This state either generates: 1) a response, from cache or error, 2) a * priming event, or 3) forwards the request to the next state (init2, * generally). * * @param qstate: query state. * @param iq: iterator query state. * @param ie: iterator shared global environment. * @param id: module id. * @return true if the event needs more request processing immediately, * false if not. */ static int processInitRequest(struct module_qstate* qstate, struct iter_qstate* iq, struct iter_env* ie, int id) { int d; uint8_t* delname; size_t delnamelen; struct dns_msg* msg; log_nametypeclass("resolving", qstate->qinfo.qname, qstate->qinfo.qtype, qstate->qinfo.qclass); /* check effort */ /* We enforce a maximum number of query restarts. This is primarily a * cheap way to prevent CNAME loops. */ if(iq->query_restart_count > MAX_RESTART_COUNT) { verbose(VERB_DETAIL, "request has exceeded the maximum number" " of query restarts with %d", iq->query_restart_count); return error_response(qstate, iq, LDNS_RCODE_SERVFAIL); } /* We enforce a maximum recursion/dependency depth -- in general, * this is unnecessary for dependency loops (although it will * catch those), but it provides a sensible limit to the amount * of work required to answer a given query. */ d = module_subreq_depth(qstate); verbose(VERB_ALGO, "request has dependency depth of %d", d); if(d > ie->max_dependency_depth) { verbose(VERB_DETAIL, "request has exceeded the maximum " "dependency depth with depth of %d", d); return error_response(qstate, iq, LDNS_RCODE_SERVFAIL); } /* Resolver Algorithm Step 1 -- Look for the answer in local data. */ /* This either results in a query restart (CNAME cache response), a * terminating response (ANSWER), or a cache miss (null). */ msg = dns_cache_lookup(qstate->env, qstate->qinfo.qname, qstate->qinfo.qname_len, qstate->qinfo.qtype, qstate->qinfo.qclass, qstate->region, qstate->scratch); if(msg) { /* handle positive cache response */ enum response_type type = response_type_from_cache(msg, &qstate->qinfo); if(type == RESPONSE_TYPE_CNAME) { uint8_t* sname = 0; size_t slen = 0; verbose(VERB_ALGO, "returning CNAME response from " "cache"); if(!iq->orig_qname) { iq->orig_qname = qstate->qinfo.qname; iq->orig_qnamelen = qstate->qinfo.qname_len; } if(!handle_cname_response(qstate, iq, msg, &sname, &slen)) return error_response(qstate, iq, LDNS_RCODE_SERVFAIL); qstate->qinfo.qname = sname; qstate->qinfo.qname_len = slen; /* This *is* a query restart, even if it is a cheap * one. */ iq->query_restart_count++; return next_state(qstate, iq, INIT_REQUEST_STATE); } /* it is an answer, response, to final state */ verbose(VERB_ALGO, "returning answer from cache."); iq->response = msg; return final_state(qstate, iq); } /* TODO attempt to forward the request */ /* if (forwardRequest(event, state, req)) { // the request has been forwarded. // forwarded requests need to be immediately sent to the // next state, QUERYTARGETS. return nextState(event, req, state, IterEventState.QUERYTARGETS_STATE); } */ /* TODO attempt to find a covering DNAME in the cache */ /* resp = mDNSCache.findDNAME(req.getQName(), req.getQType(), req .getQClass()); if (resp != null) { log.trace("returning synthesized CNAME response from cache: " + resp); Name cname = handleCNAMEResponse(state, req, resp); // At this point, we just initiate the query restart. // This might not be a query restart situation (e.g., qtype == CNAME), // but // the answer returned from findDNAME() is likely to be one that we // don't want to return. // Thus we allow the cache and other resolution mojo kick in regardless. req.setQName(cname); state.queryRestartCount++; return nextState(event, req, state, IterEventState.INIT_REQUEST_STATE); } */ /* Resolver Algorithm Step 2 -- find the "best" servers. */ /* first, adjust for DS queries. To avoid the grandparent problem, * we just look for the closest set of server to the parent of qname. */ delname = qstate->qinfo.qname; delnamelen = qstate->qinfo.qname_len; if(qstate->qinfo.qtype == LDNS_RR_TYPE_DS && delname[0] != 0) { /* do not adjust root label, remove first label from delname */ size_t lablen = delname[0] + 1; delname += lablen; delnamelen -= lablen; } /* Lookup the delegation in the cache. If null, then the cache needs * to be primed for the qclass. */ iq->dp = dns_cache_find_delegation(qstate->env, delname, delnamelen, qstate->qinfo.qtype, qstate->qinfo.qclass, qstate->region, &iq->deleg_msg); /* If the cache has returned nothing, then we have a root priming * situation. */ if(iq->dp == NULL) { /* Note that the result of this will set a new * DelegationPoint based on the result of priming. */ if(!prime_root(qstate, ie, id, qstate->qinfo.qclass)) return error_response(qstate, iq, LDNS_RCODE_REFUSED); /* priming creates an sends a subordinate query, with * this query as the parent. So further processing for * this event will stop until reactivated by the results * of priming. */ return 0; } /* Reset the RD flag. If this is a query restart, then the RD * will have been turned off. */ if(iq->orig_qflags & BIT_RD) qstate->query_flags |= BIT_RD; else qstate->query_flags &= ~BIT_RD; /* Otherwise, set the current delegation point and move on to the * next state. */ return next_state(qstate, iq, INIT_REQUEST_2_STATE); } /** * Process the second part of the initial request handling. This state * basically exists so that queries that generate root priming events have * the same init processing as ones that do not. Request events that reach * this state must have a valid currentDelegationPoint set. * * This part is primarly handling stub zone priming. Events that reach this * state must have a current delegation point. * * @param qstate: query state. * @param iq: iterator query state. * @param ie: iterator shared global environment. * @param id: module id. * @return true if the event needs more request processing immediately, * false if not. */ static int processInitRequest2(struct module_qstate* qstate, struct iter_qstate* iq, struct iter_env* ie, int id) { log_nametypeclass("resolving (init part 2): ", qstate->qinfo.qname, qstate->qinfo.qtype, qstate->qinfo.qclass); /* Check to see if we need to prime a stub zone. */ if(prime_stub(qstate, iq, ie, id, qstate->qinfo.qname, qstate->qinfo.qclass)) { /* A priming sub request was made */ return 0; } /* most events just get forwarded to the next state. */ return next_state(qstate, iq, INIT_REQUEST_3_STATE); } /** * Process the third part of the initial request handling. This state exists * as a separate state so that queries that generate stub priming events * will get the tail end of the init process but not repeat the stub priming * check. * * @param qstate: query state. * @param iq: iterator query state. * @return true, advancing the event to the QUERYTARGETS_STATE. */ static int processInitRequest3(struct module_qstate* qstate, struct iter_qstate* iq) { log_nametypeclass("resolving (init part 3): ", qstate->qinfo.qname, qstate->qinfo.qtype, qstate->qinfo.qclass); /* If the RD flag wasn't set, then we just finish with the * cached referral as the response. */ if(!(qstate->query_flags & BIT_RD)) { iq->response = iq->deleg_msg; return final_state(qstate, iq); } /* After this point, unset the RD flag -- this query is going to * be sent to an auth. server. */ qstate->query_flags &= ~BIT_RD; /* Jump to the next state. */ return next_state(qstate, iq, QUERYTARGETS_STATE); } /** * Given a basic query, generate a "target" query. These are subordinate * queries for missing delegation point target addresses. * * @param qstate: query state. * @param iq: iterator query state. * @param id: module id. * @param name: target qname. * @param namelen: target qname length. * @param qtype: target qtype (either A or AAAA). * @param qclass: target qclass. * @return true on success, false on failure. */ static int generate_target_query(struct module_qstate* qstate, struct iter_qstate* iq, int id, uint8_t* name, size_t namelen, uint16_t qtype, uint16_t qclass) { struct module_qstate* subq = generate_sub_request(name, namelen, qtype, qclass, qstate, id, INIT_REQUEST_STATE, TARGET_RESP_STATE); struct iter_qstate* subiq; if(!subq) return 0; subiq = (struct iter_qstate*)subq->minfo[id]; subiq->dp = delegpt_copy(iq->dp, subq->region); if(!subiq->dp) { subq->ext_state[id] = module_error; return 0; } return 1; } /** * Given an event at a certain state, generate zero or more target queries * for it's current delegation point. * * @param qstate: query state. * @param iq: iterator query state. * @param ie: iterator shared global environment. * @param id: module id. * @param maxtargets: The maximum number of targets to query for. * if it is negative, there is no maximum number of targets. * @param num: returns the number of queries generated and processed, * which may be zero if there were no missing targets. * @return false on error. */ static int query_for_targets(struct module_qstate* qstate, struct iter_qstate* iq, struct iter_env* ie, int id, int maxtargets, int* num) { int query_count = 0; int target_count = 0; struct delegpt_ns* ns = iq->dp->nslist; /* Generate target requests. Basically, any missing targets * are queried for here, regardless if it is necessary to do * so to continue processing. */ /* loop over missing targets */ for(ns = iq->dp->nslist; ns; ns = ns->next) { if(ns->resolved) continue; /* Sanity check: if the target name is at or *below* the * delegation point itself, then this will be (potentially) * unresolvable. This is the one case where glue *must* * have been present. * FIXME: at this point, this *may* be resolvable, so * perhaps we should issue the query anyway and let it fail.*/ if(dname_subdomain_c(ns->name, iq->dp->name)) { log_nametypeclass("skipping target name because " "it should have been glue", ns->name, LDNS_RR_TYPE_NS, qstate->qinfo.qclass); continue; } if(ie->supports_ipv6) { /* Send the AAAA request. */ if(!generate_target_query(qstate, iq, id, ns->name, ns->namelen, LDNS_RR_TYPE_AAAA, qstate->qinfo.qclass)) return 0; query_count++; } /* Send the A request. */ if(!generate_target_query(qstate, iq, id, ns->name, ns->namelen, LDNS_RR_TYPE_A, qstate->qinfo.qclass)) return 0; query_count++; /* mark this target as in progress. */ ns->resolved = 1; /* if maxtargets is negative, there is no maximum, * otherwise only query for ntarget names. */ if(maxtargets > 0 && ++target_count > maxtargets) break; } *num = query_count; return 1; } /** * This is the request event state where the request will be sent to one of * its current query targets. This state also handles issuing target lookup * queries for missing target IP addresses. Queries typically iterate on * this state, both when they are just trying different targets for a given * delegation point, and when they change delegation points. This state * roughly corresponds to RFC 1034 algorithm steps 3 and 4. * * @param qstate: query state. * @param iq: iterator query state. * @param ie: iterator shared global environment. * @param id: module id. * @return true if the event requires more request processing immediately, * false if not. This state only returns true when it is generating * a SERVFAIL response because the query has hit a dead end. */ static int processQueryTargets(struct module_qstate* qstate, struct iter_qstate* iq, struct iter_env* ie, int id) { int tf_policy, d; struct delegpt_addr* target; struct outbound_entry* outq; /* NOTE: a request will encounter this state for each target it * needs to send a query to. That is, at least one per referral, * more if some targets timeout or return throwaway answers. */ log_nametypeclass("processQueryTargets:", qstate->qinfo.qname, qstate->qinfo.qtype, qstate->qinfo.qclass); verbose(VERB_ALGO, "processQueryTargets: targetqueries %d, " "currentqueries %d", iq->num_target_queries, iq->num_current_queries); /* Make sure that we haven't run away */ /* FIXME: is this check even necessary? */ if(iq->referral_count > MAX_REFERRAL_COUNT) { verbose(VERB_ALGO, "request has exceeded the maximum " "number of referrrals with %d", iq->referral_count); return error_response(qstate, iq, LDNS_RCODE_SERVFAIL); } tf_policy = 0; d = module_subreq_depth(qstate); if(d <= ie->max_dependency_depth) { tf_policy = ie->target_fetch_policy[d]; } /* if there is a policy to fetch missing targets * opportunistically, do it. we rely on the fact that once a * query (or queries) for a missing name have been issued, * they will not be show up again. */ if(tf_policy != 0) { if(!query_for_targets(qstate, iq, ie, id, tf_policy, &iq->num_target_queries)) { return error_response(qstate, iq, LDNS_RCODE_SERVFAIL); } } else { iq->num_target_queries = 0; } /* Add the current set of unused targets to our queue. */ delegpt_add_unused_targets(iq->dp); /* Select the next usable target, filtering out unsuitable targets. */ target = iter_server_selection(ie, qstate->env, iq->dp, iq->dp->name, iq->dp->namelen); /* If no usable target was selected... */ if(!target) { /* Here we distinguish between three states: generate a new * target query, just wait, or quit (with a SERVFAIL). * We have the following information: number of active * target queries, number of active current queries, * the presence of missing targets at this delegation * point, and the given query target policy. */ /* Check for the wait condition. If this is true, then * an action must be taken. */ if(iq->num_target_queries==0 && iq->num_current_queries==0) { /* If there is nothing to wait for, then we need * to distinguish between generating (a) new target * query, or failing. */ if(delegpt_count_missing_targets(iq->dp) > 0) { verbose(VERB_ALGO, "querying for next " "missing target"); if(!query_for_targets(qstate, iq, ie, id, 1, &iq->num_target_queries)) { return error_response(qstate, iq, LDNS_RCODE_SERVFAIL); } } /* Since a target query might have been made, we * need to check again. */ if(iq->num_target_queries == 0) { verbose(VERB_ALGO, "out of query targets -- " "returning SERVFAIL"); /* fail -- no more targets, no more hope * of targets, no hope of a response. */ return error_response(qstate, iq, LDNS_RCODE_SERVFAIL); } } /* otherwise, we have no current targets, so submerge * until one of the target or direct queries return. */ if(iq->num_target_queries>0 && iq->num_current_queries>0) verbose(VERB_ALGO, "no current targets -- waiting " "for %d targets to resolve or %d outstanding" " queries to respond", iq->num_target_queries, iq->num_current_queries); else if(iq->num_target_queries>0) verbose(VERB_ALGO, "no current targets -- waiting " "for %d targets to resolve.", iq->num_target_queries); else verbose(VERB_ALGO, "no current targets -- waiting " "for %d outstanding queries to respond.", iq->num_current_queries); return 0; } /* We have a valid target. */ log_nametypeclass("sending query:", qstate->qinfo.qname, qstate->qinfo.qtype, qstate->qinfo.qclass); log_addr("sending to target:", &target->addr, target->addrlen); outq = (*qstate->env->send_query)( qstate->qinfo.qname, qstate->qinfo.qname_len, qstate->qinfo.qtype, qstate->qinfo.qclass, qstate->query_flags, 1, &target->addr, target->addrlen, qstate); if(!outq) { log_err("out of memory sending query to auth server"); return error_response(qstate, iq, LDNS_RCODE_SERVFAIL); } outbound_list_insert(&iq->outlist, outq); iq->num_current_queries++; qstate->ext_state[id] = module_wait_reply; return 0; } #if 0 /** TODO */ static int processQueryResponse(struct module_qstate* qstate, struct iter_qstate* iq, struct iter_env* ie, int id) { return 0; } /** TODO */ static int processPrimeResponse(struct module_qstate* qstate, struct iter_qstate* iq, struct iter_env* ie, int id) { return 0; } /** TODO */ static int processTargetResponse(struct module_qstate* qstate, struct iter_qstate* iq, struct iter_env* ie, int id) { return 0; } /** TODO */ static int processFinished(struct module_qstate* qstate, struct iter_qstate* iq, struct iter_env* ie, int id) { return 0; } #endif /** * Handle iterator state. * Handle events. This is the real processing loop for events, responsible * for moving events through the various states. If a processing method * returns true, then it will be advanced to the next state. If false, then * processing will stop. * * @param qstate: query state. * @param ie: iterator shared global environment. * @param iq: iterator query state. * @param id: module id. */ static void iter_handle(struct module_qstate* qstate, struct iter_qstate* iq, struct iter_env* ie, int id) { int cont = 1; while(cont) { verbose(VERB_ALGO, "iter_handle processing q with state %s", iter_state_to_string(iq->state)); switch(iq->state) { case INIT_REQUEST_STATE: cont = processInitRequest(qstate, iq, ie, id); break; case INIT_REQUEST_2_STATE: cont = processInitRequest2(qstate, iq, ie, id); break; case INIT_REQUEST_3_STATE: cont = processInitRequest3(qstate, iq); break; case QUERYTARGETS_STATE: cont = processQueryTargets(qstate, iq, ie, id); break; #if 0 case QUERY_RESP_STATE: cont = processQueryResponse(qstate, iq, ie, id); break; case PRIME_RESP_STATE: cont = processPrimeResponse(qstate, iq, ie, id); break; case TARGET_RESP_STATE: cont = processTargetResponse(qstate, iq, ie, id); break; case FINISHED_STATE: cont = processFinished(qstate, iq, ie, id); break; #endif default: log_warn("iterator: invalid state: %d", iq->state); cont = 0; break; } } } /** * This is the primary entry point for processing request events. Note that * this method should only be used by external modules. * @param qstate: query state. * @param ie: iterator shared global environment. * @param iq: iterator query state. * @param id: module id. */ static void process_request(struct module_qstate* qstate, struct iter_qstate* iq, struct iter_env* ie, int id) { /* external requests start in the INIT state, and finish using the * FINISHED state. */ iq->state = INIT_REQUEST_STATE; iq->final_state = FINISHED_STATE; verbose(VERB_ALGO, "process_request: new external request event"); iter_handle(qstate, iq, ie, id); } /** process authoritative server reply */ static void process_response(struct module_qstate* qstate, struct iter_qstate* iq, struct iter_env* ie, int id, struct outbound_entry* outbound, enum module_ev event) { struct msg_parse* prs; struct edns_data edns; ldns_buffer* pkt; verbose(VERB_ALGO, "process_response: new external response event"); iq->response = NULL; iq->state = QUERY_RESP_STATE; if(event == module_event_timeout || event == module_event_error) { goto handle_it; } if(event != module_event_reply || !qstate->reply) { log_err("Bad event combined with response"); outbound_list_remove(&iq->outlist, outbound); qstate->ext_state[id] = module_error; return; } /* parse message */ prs = (struct msg_parse*)region_alloc(qstate->scratch, sizeof(struct msg_parse)); if(!prs) { log_err("out of memory on incoming message"); /* like packet got dropped */ goto handle_it; } memset(prs, 0, sizeof(*prs)); memset(&edns, 0, sizeof(edns)); pkt = qstate->reply->c->buffer; ldns_buffer_set_position(pkt, 0); if(!parse_packet(pkt, prs, qstate->scratch)) goto handle_it; /* edns is not examined, but removed from message to help cache */ if(!parse_extract_edns(prs, &edns)) goto handle_it; /* normalize and sanitize: easy to delete items from linked lists */ if(!scrub_message(pkt, prs, &qstate->qinfo, iq->dp->name, qstate->scratch)) goto handle_it; /* allocate response dns_msg in region */ iq->response = dns_alloc_msg(prs, qstate->region); if(!iq->response) goto handle_it; handle_it: outbound_list_remove(&iq->outlist, outbound); iter_handle(qstate, iq, ie, id); } /** iterator operate on a query */ static void iter_operate(struct module_qstate* qstate, enum module_ev event, int id, struct outbound_entry* outbound) { struct iter_env* ie = (struct iter_env*)qstate->env->modinfo[id]; struct iter_qstate* iq = (struct iter_qstate*)qstate->minfo[id]; verbose(VERB_ALGO, "iterator[module %d] operate: extstate:%s event:%s", id, strextstate(qstate->ext_state[id]), strmodulevent(event)); if(ie->fwd_addrlen != 0) { perform_forward(qstate, event, id, outbound); return; } /* perform iterator state machine */ if(event == module_event_new && iq == NULL) { log_info("iter state machine"); if(!iter_new(qstate, id)) { qstate->ext_state[id] = module_error; return; } iq = (struct iter_qstate*)qstate->minfo[id]; process_request(qstate, iq, ie, id); return; } if(event == module_event_pass) { iter_handle(qstate, iq, ie, id); return; } if(outbound) { process_response(qstate, iq, ie, id, outbound, event); return; } /* TODO: uhh */ log_err("bad event for iterator"); qstate->ext_state[id] = module_error; } /** iterator cleanup query state */ static void iter_clear(struct module_qstate* qstate, int id) { struct iter_qstate* iq; if(!qstate) return; iq = (struct iter_qstate*)qstate->minfo[id]; if(iq->orig_qname) { /* so the correct qname gets free'd */ qstate->qinfo.qname = iq->orig_qname; qstate->qinfo.qname_len = iq->orig_qnamelen; } outbound_list_clear(&iq->outlist); qstate->minfo[id] = NULL; } /** * The iterator function block */ static struct module_func_block iter_block = { "iterator", &iter_init, &iter_deinit, &iter_operate, &iter_clear }; struct module_func_block* iter_get_funcblock() { return &iter_block; } const char* iter_state_to_string(enum iter_state state) { switch (state) { case INIT_REQUEST_STATE : return "INIT REQUEST STATE"; case INIT_REQUEST_2_STATE : return "INIT REQUEST STATE (stage 2)"; case INIT_REQUEST_3_STATE: return "INIT REQUEST STATE (stage 3)"; case QUERYTARGETS_STATE : return "QUERY TARGETS STATE"; case PRIME_RESP_STATE : return "PRIME RESPONSE STATE"; case QUERY_RESP_STATE : return "QUERY RESPONSE STATE"; case TARGET_RESP_STATE : return "TARGET RESPONSE STATE"; case FINISHED_STATE : return "FINISHED RESPONSE STATE"; default : return "UNKNOWN ITER STATE"; } } int iter_state_is_responsestate(enum iter_state s) { switch(s) { case INIT_REQUEST_STATE : case INIT_REQUEST_2_STATE : case INIT_REQUEST_3_STATE : case QUERYTARGETS_STATE : return 0; default: break; } return 1; }