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- new approach to NS fetches for DS lookup that works with

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cornercases, and is more robust and considers forwarders.


git-svn-id: file:///svn/unbound/trunk@2646 be551aaa-1e26-0410-a405-d3ace91eadb9
This commit is contained in:
Wouter Wijngaards 2012-03-21 15:01:01 +00:00
parent 0d5441bd8a
commit fa3337d42a
7 changed files with 388 additions and 37 deletions
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4
doc/Changelog
View File

@ -1,3 +1,7 @@
21 March 2012: Wouter
- new approach to NS fetches for DS lookup that works with
cornercases, and is more robust and considers forwarders.
19 March 2012: Wouter
- iana portlist updated.
- fix to locate nameservers for DS lookup with NS fetches.

45
iterator/iter_utils.c
View File

@ -970,20 +970,51 @@ void iter_merge_retry_counts(struct delegpt* dp, struct delegpt* old)
}
int
iter_ds_toolow(struct dns_msg* msg)
iter_ds_toolow(struct dns_msg* msg, struct delegpt* dp)
{
/* if for query example.com, there is example.com SOA or a subdomain
* of example.com, then we are too low and need to fetch NS. */
size_t i = msg->rep->an_numrrsets;
for(; i < msg->rep->an_numrrsets + msg->rep->ns_numrrsets; i++) {
size_t i;
/* if we have a DNAME or CNAME we are probably wrong */
/* if we have a qtype DS in the answer section, its fine */
for(i=0; i < msg->rep->an_numrrsets; i++) {
struct ub_packed_rrset_key* s = msg->rep->rrsets[i];
if(ntohs(s->rk.type) == LDNS_RR_TYPE_SOA &&
dname_subdomain_c(s->rk.dname, msg->qinfo.qname)) {
/* point is too low */
if(ntohs(s->rk.type) == LDNS_RR_TYPE_DNAME ||
ntohs(s->rk.type) == LDNS_RR_TYPE_CNAME) {
/* not the right answer, maybe too low, check the
* RRSIG signer name (if there is any) for a hint
* that it is from the dp zone anyway */
uint8_t* sname;
size_t slen;
val_find_rrset_signer(s, &sname, &slen);
if(sname && query_dname_compare(dp->name, sname)==0)
return 0; /* it is fine, from the right dp */
return 1;
}
if(ntohs(s->rk.type) == LDNS_RR_TYPE_DS)
return 0; /* fine, we have a DS record */
}
for(i=msg->rep->an_numrrsets;
i < msg->rep->an_numrrsets + msg->rep->ns_numrrsets; i++) {
struct ub_packed_rrset_key* s = msg->rep->rrsets[i];
if(ntohs(s->rk.type) == LDNS_RR_TYPE_SOA) {
if(dname_subdomain_c(s->rk.dname, msg->qinfo.qname))
return 1; /* point is too low */
if(query_dname_compare(s->rk.dname, dp->name)==0)
return 0; /* right dp */
}
if(ntohs(s->rk.type) == LDNS_RR_TYPE_NSEC ||
ntohs(s->rk.type) == LDNS_RR_TYPE_NSEC3) {
uint8_t* sname;
size_t slen;
val_find_rrset_signer(s, &sname, &slen);
if(sname && query_dname_compare(dp->name, sname)==0)
return 0; /* it is fine, from the right dp */
return 1;
}
}
return 0;
/* we do not know */
return 1;
}
int iter_dp_cangodown(struct query_info* qinfo, struct delegpt* dp)

5
iterator/iter_utils.h
View File

@ -314,10 +314,13 @@ void iter_merge_retry_counts(struct delegpt* dp, struct delegpt* old);
/**
* See if a DS response (type ANSWER) is too low: a nodata answer with
* a SOA record in the authority section at-or-below the qchase.qname.
* Also returns true if we are not sure (i.e. empty message, CNAME nosig).
* @param msg: the response.
* @param dp: the dp name is used to check if the RRSIG gives a clue that
* it was originated from the correct nameserver.
* @return true if too low.
*/
int iter_ds_toolow(struct dns_msg* msg);
int iter_ds_toolow(struct dns_msg* msg, struct delegpt* dp);
/**
* See if delegpt can go down a step to the qname or not

66
iterator/iterator.c
View File

@ -1530,10 +1530,8 @@ processLastResort(struct module_qstate* qstate, struct iter_qstate* iq,
* Try to find the NS record set that will resolve a qtype DS query. Due
* to grandparent/grandchild reasons we did not get a proper lookup right
* away. We need to create type NS queries until we get the right parent
* for this lookup. We add labels to the delegation point - whose name is
* storage for where we are (with empty other content). Until we find an
* NS record, then we try the query again (which can result in doing this
* again). Or we go too low, it is not possible to resolve, servfail.
* for this lookup. We remove labels from the query to find the right point.
* If we end up at the old dp name, then there is no solution.
*
* @param qstate: query state.
* @param iq: iterator query state.
@ -1546,32 +1544,34 @@ static int
processDSNSFind(struct module_qstate* qstate, struct iter_qstate* iq,
int id)
{
int qlab = dname_count_labels(iq->qchase.qname);
struct module_qstate* subq = NULL;
verbose(VERB_ALGO, "processDSNSFind");
if(dname_subdomain_c(iq->dp->name, iq->qchase.qname) ||
qlab == iq->dp->namelabs+1)
/* we are too low - fail (robust check) */
if(!iq->dsns_point) {
/* initialize */
iq->dsns_point = iq->qchase.qname;
iq->dsns_point_len = iq->qchase.qname_len;
}
/* robustcheck for internal error: we are not underneath the dp */
if(!dname_subdomain_c(iq->dsns_point, iq->dp->name)) {
return error_response_cache(qstate, id, LDNS_RCODE_SERVFAIL);
/* dp is used for storage, this is our state */
log_assert(!iq->dp->dp_type_mlc); /* if malloced this would leak */
iq->dp->nslist = NULL;
iq->dp->target_list = NULL;
iq->dp->usable_list = NULL;
iq->dp->result_list = NULL;
}
/* go up one (more) step, until we hit the dp, if so, end */
dname_remove_label(&iq->dsns_point, &iq->dsns_point_len);
if(query_dname_compare(iq->dsns_point, iq->dp->name) == 0) {
/* there was no inbetween nameserver, use the old delegation
* point again. And this time, because dsns_point is nonNULL
* we are going to accept the (bad) result */
iq->state = QUERYTARGETS_STATE;
return 1;
}
iq->state = DSNS_FIND_STATE;
/* add one label to the dp */
iq->dp->name = iq->qchase.qname;
iq->dp->namelen = iq->qchase.qname_len;
/* we have qlab labels we want namelabs+1 labels */
dname_remove_labels(&iq->dp->name, &iq->dp->namelen,
qlab - (iq->dp->namelabs+1));
iq->dp->namelabs++;
/* spawn NS lookup (validation not needed, this is for DS lookup) */
log_nametypeclass(VERB_ALGO, "fetch nameservers",
iq->dp->name, LDNS_RR_TYPE_NS, iq->qchase.qclass);
if(!generate_sub_request(iq->dp->name, iq->dp->namelen,
iq->dsns_point, LDNS_RR_TYPE_NS, iq->qchase.qclass);
if(!generate_sub_request(iq->dsns_point, iq->dsns_point_len,
LDNS_RR_TYPE_NS, iq->qchase.qclass, qstate, id, iq,
INIT_REQUEST_STATE, FINISHED_STATE, &subq, 0)) {
return error_response_cache(qstate, id, LDNS_RCODE_SERVFAIL);
@ -1903,8 +1903,9 @@ processQueryResponse(struct module_qstate* qstate, struct iter_qstate* iq,
}
/* if qtype is DS, check we have the right level of answer,
* like grandchild answer but we need the middle, reject it */
if(iq->qchase.qtype == LDNS_RR_TYPE_DS
&& iter_ds_toolow(iq->response)
if(iq->qchase.qtype == LDNS_RR_TYPE_DS && !iq->dsns_point
&& !(iq->chase_flags&BIT_RD)
&& iter_ds_toolow(iq->response, iq->dp)
&& iter_dp_cangodown(&iq->qchase, iq->dp))
return processDSNSFind(qstate, iq, id);
if(!iter_dns_store(qstate->env, &iq->response->qinfo,
@ -2026,6 +2027,13 @@ processQueryResponse(struct module_qstate* qstate, struct iter_qstate* iq,
if(verbosity >= VERB_ALGO)
log_dns_msg("cname msg", &iq->response->qinfo,
iq->response->rep);
/* if qtype is DS, check we have the right level of answer,
* like grandchild answer but we need the middle, reject it */
if(iq->qchase.qtype == LDNS_RR_TYPE_DS && !iq->dsns_point
&& !(iq->chase_flags&BIT_RD)
&& iter_ds_toolow(iq->response, iq->dp)
&& iter_dp_cangodown(&iq->qchase, iq->dp))
return processDSNSFind(qstate, iq, id);
/* Process the CNAME response. */
if(!handle_cname_response(qstate, iq, iq->response,
&sname, &snamelen))
@ -2036,8 +2044,7 @@ processQueryResponse(struct module_qstate* qstate, struct iter_qstate* iq,
/* prefetchleeway applied because this updates answer parts */
if(!iter_dns_store(qstate->env, &iq->response->qinfo,
iq->response->rep, 1, qstate->prefetch_leeway,
iq->dp&&iq->dp->has_parent_side_NS,
NULL))
iq->dp&&iq->dp->has_parent_side_NS, NULL))
return error_response(qstate, id, LDNS_RCODE_SERVFAIL);
/* set the current request's qname to the new value. */
iq->qchase.qname = sname;
@ -2045,6 +2052,7 @@ processQueryResponse(struct module_qstate* qstate, struct iter_qstate* iq,
/* Clear the query state, since this is a query restart. */
iq->deleg_msg = NULL;
iq->dp = NULL;
iq->dsns_point = NULL;
/* Note the query restart. */
iq->query_restart_count++;
iq->sent_count = 0;
@ -2321,7 +2329,7 @@ processDSNSResponse(struct module_qstate* qstate, int id,
struct iter_qstate* foriq = (struct iter_qstate*)forq->minfo[id];
/* if the finished (iq->response) query has no NS set: continue
* down to look for the right dp; nothing to change, do DPNSstate */
* up to look for the right dp; nothing to change, do DPNSstate */
if(qstate->return_rcode != LDNS_RCODE_NOERROR)
return; /* seek further */
/* find the NS RRset (without allowing CNAMEs) */
@ -2340,7 +2348,7 @@ processDSNSResponse(struct module_qstate* qstate, int id,
}
/* success, go query the querytargets in the new dp (and go down) */
}
/**
* Process response for qclass=ANY queries for a particular class.
* Append to result or error-exit.

5
iterator/iterator.h
View File

@ -275,6 +275,11 @@ struct iter_qstate {
/** the parent-side-glue element (NULL if none, its first match) */
struct ub_packed_rrset_key* pside_glue;
/** If nonNULL we are walking upwards from DS query to find NS */
uint8_t* dsns_point;
/** length of the dname in dsns_point */
size_t dsns_point_len;
/**
* expected dnssec information for this iteration step.
* If dnssec rrsigs are expected and not given, the server is marked

155
testdata/iter_ds_locate_ns_cname.rpl vendored Normal file
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@ -0,0 +1,155 @@
; config options
server:
target-fetch-policy: "0 0 0 0 0"
stub-zone:
name: "."
stub-addr: 193.0.14.129 # K.ROOT-SERVERS.NET.
CONFIG_END
SCENARIO_BEGIN Test locate of NS records for DS with CNAME
; K.ROOT-SERVERS.NET.
RANGE_BEGIN 0 100
ADDRESS 193.0.14.129
ENTRY_BEGIN
MATCH opcode qtype qname
ADJUST copy_id
REPLY QR AA NOERROR
SECTION QUESTION
. IN NS
SECTION ANSWER
. IN NS K.ROOT-SERVERS.NET.
SECTION ADDITIONAL
K.ROOT-SERVERS.NET. IN A 193.0.14.129
ENTRY_END
; content of root-servers.net
ENTRY_BEGIN
MATCH opcode qtype qname
ADJUST copy_id
REPLY QR AA NOERROR
SECTION QUESTION
root-servers.net. IN NS
SECTION ANSWER
root-servers.net. IN NS K.ROOT-SERVERS.NET.
SECTION ADDITIONAL
K.ROOT-SERVERS.NET. IN A 193.0.14.129
ENTRY_END
ENTRY_BEGIN
MATCH opcode qtype qname
ADJUST copy_id
REPLY QR AA NOERROR
SECTION QUESTION
k.root-servers.net. IN A
SECTION ANSWER
K.ROOT-SERVERS.NET. IN A 193.0.14.129
SECTION AUTHORITY
root-servers.net. IN NS K.ROOT-SERVERS.NET.
ENTRY_END
ENTRY_BEGIN
MATCH opcode qtype qname
ADJUST copy_id
REPLY QR AA NOERROR
SECTION QUESTION
k.root-servers.net. IN AAAA
SECTION ANSWER
SECTION AUTHORITY
root-servers.net. IN SOA K.ROOT-SERVERS.NET. hostmaster. 1 2 3 4 5
ENTRY_END
ENTRY_BEGIN
MATCH opcode qtype qname
ADJUST copy_id
REPLY QR AA NOERROR
SECTION QUESTION
root-servers.net. IN DS
SECTION ANSWER
root-servers.net. IN CNAME blabla.com.
ENTRY_END
ENTRY_BEGIN
MATCH opcode subdomain
ADJUST copy_id copy_query
REPLY QR NOERROR
SECTION QUESTION
net. IN A
SECTION AUTHORITY
net. IN NS a.gtld-servers.net.
SECTION ADDITIONAL
a.gtld-servers.net. IN A 192.5.6.30
ENTRY_END
ENTRY_BEGIN
MATCH opcode qtype qname
ADJUST copy_id
REPLY QR AA NXDOMAIN
SECTION QUESTION
blabla.com. IN DS
SECTION ANSWER
SECTION AUTHORITY
. IN SOA K.ROOT-SERVERS.NET. hostmaster. 1 2 3 4 5
ENTRY_END
RANGE_END
; a.gtld-servers.net.
RANGE_BEGIN 0 100
ADDRESS 192.5.6.30
ENTRY_BEGIN
MATCH opcode qtype qname
ADJUST copy_id
REPLY QR AA NOERROR
SECTION QUESTION
net. IN NS
SECTION ANSWER
net. IN NS a.gtld-servers.net.
SECTION ADDITIONAL
a.gtld-servers.net. IN A 192.5.6.30
ENTRY_END
ENTRY_BEGIN
MATCH opcode qtype qname
ADJUST copy_id
REPLY QR AA NOERROR
SECTION QUESTION
root-servers.net. IN DS
SECTION AUTHORITY
net. IN SOA a.gtld-servers.net. hostmaster. 2 3 4 5 6
ENTRY_END
ENTRY_BEGIN
MATCH opcode subdomain
ADJUST copy_id copy_query
REPLY QR NOERROR
SECTION QUESTION
root-servers.net. IN A
SECTION AUTHORITY
root-servers.net. IN NS K.ROOT-SERVERS.NET.
SECTION ADDITIONAL
K.ROOT-SERVERS.NET. IN A 193.0.14.129
ENTRY_END
RANGE_END
STEP 1 QUERY
ENTRY_BEGIN
REPLY RD
SECTION QUESTION
root-servers.net. IN DS
ENTRY_END
; recursion happens here.
STEP 10 CHECK_ANSWER
ENTRY_BEGIN
MATCH all
REPLY QR RD RA NOERROR
SECTION QUESTION
root-servers.net. IN DS
SECTION ANSWER
SECTION AUTHORITY
net. IN SOA a.gtld-servers.net. hostmaster. 2 3 4 5 6
SECTION ADDITIONAL
ENTRY_END
SCENARIO_END

145
testdata/iter_ds_locate_ns_nosoa.rpl vendored Normal file
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@ -0,0 +1,145 @@
; config options
server:
target-fetch-policy: "0 0 0 0 0"
stub-zone:
name: "."
stub-addr: 193.0.14.129 # K.ROOT-SERVERS.NET.
CONFIG_END
SCENARIO_BEGIN Test locate of NS records for DS without a SOA record
; K.ROOT-SERVERS.NET.
RANGE_BEGIN 0 100
ADDRESS 193.0.14.129
ENTRY_BEGIN
MATCH opcode qtype qname
ADJUST copy_id
REPLY QR AA NOERROR
SECTION QUESTION
. IN NS
SECTION ANSWER
. IN NS K.ROOT-SERVERS.NET.
SECTION ADDITIONAL
K.ROOT-SERVERS.NET. IN A 193.0.14.129
ENTRY_END
; content of root-servers.net
ENTRY_BEGIN
MATCH opcode qtype qname
ADJUST copy_id
REPLY QR AA NOERROR
SECTION QUESTION
root-servers.net. IN NS
SECTION ANSWER
root-servers.net. IN NS K.ROOT-SERVERS.NET.
SECTION ADDITIONAL
K.ROOT-SERVERS.NET. IN A 193.0.14.129
ENTRY_END
ENTRY_BEGIN
MATCH opcode qtype qname
ADJUST copy_id
REPLY QR AA NOERROR
SECTION QUESTION
k.root-servers.net. IN A
SECTION ANSWER
K.ROOT-SERVERS.NET. IN A 193.0.14.129
SECTION AUTHORITY
root-servers.net. IN NS K.ROOT-SERVERS.NET.
ENTRY_END
ENTRY_BEGIN
MATCH opcode qtype qname
ADJUST copy_id
REPLY QR AA NOERROR
SECTION QUESTION
k.root-servers.net. IN AAAA
SECTION ANSWER
SECTION AUTHORITY
root-servers.net. IN SOA K.ROOT-SERVERS.NET. hostmaster. 1 2 3 4 5
ENTRY_END
ENTRY_BEGIN
MATCH opcode qtype qname
ADJUST copy_id
REPLY QR AA NOERROR
SECTION QUESTION
root-servers.net. IN DS
SECTION ANSWER
SECTION AUTHORITY
;root-servers.net. IN SOA K.ROOT-SERVERS.NET. hostmaster. 1 2 3 4 5
ENTRY_END
ENTRY_BEGIN
MATCH opcode subdomain
ADJUST copy_id copy_query
REPLY QR NOERROR
SECTION QUESTION
net. IN A
SECTION AUTHORITY
net. IN NS a.gtld-servers.net.
SECTION ADDITIONAL
a.gtld-servers.net. IN A 192.5.6.30
ENTRY_END
RANGE_END
; a.gtld-servers.net.
RANGE_BEGIN 0 100
ADDRESS 192.5.6.30
ENTRY_BEGIN
MATCH opcode qtype qname
ADJUST copy_id
REPLY QR AA NOERROR
SECTION QUESTION
net. IN NS
SECTION ANSWER
net. IN NS a.gtld-servers.net.
SECTION ADDITIONAL
a.gtld-servers.net. IN A 192.5.6.30
ENTRY_END
ENTRY_BEGIN
MATCH opcode qtype qname
ADJUST copy_id
REPLY QR AA NOERROR
SECTION QUESTION
root-servers.net. IN DS
SECTION AUTHORITY
net. IN SOA a.gtld-servers.net. hostmaster. 2 3 4 5 6
ENTRY_END
ENTRY_BEGIN
MATCH opcode subdomain
ADJUST copy_id copy_query
REPLY QR NOERROR
SECTION QUESTION
root-servers.net. IN A
SECTION AUTHORITY
root-servers.net. IN NS K.ROOT-SERVERS.NET.
SECTION ADDITIONAL
K.ROOT-SERVERS.NET. IN A 193.0.14.129
ENTRY_END
RANGE_END
STEP 1 QUERY
ENTRY_BEGIN
REPLY RD
SECTION QUESTION
root-servers.net. IN DS
ENTRY_END
; recursion happens here.
STEP 10 CHECK_ANSWER
ENTRY_BEGIN
MATCH all
REPLY QR RD RA NOERROR
SECTION QUESTION
root-servers.net. IN DS
SECTION ANSWER
SECTION AUTHORITY
net. IN SOA a.gtld-servers.net. hostmaster. 2 3 4 5 6
SECTION ADDITIONAL
ENTRY_END
SCENARIO_END