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resolved: make sure a non-existing PTR record never gets mangled into NODATA

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Previously, if a PTR query is seen for a non-existing record, we'd
generate an empty response (but not NXDOMAIN or so). Fix that. If we
have no data about an IP address, then let's say so, so that the
original error is returned, instead of anything synthesized.

Fixes: #6543
This commit is contained in:
Lennart Poettering 2017-09-29 18:02:31 +02:00
parent acf06088d3
commit 2855b6c39c
1 changed files with 26 additions and 9 deletions
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35
src/resolve/resolved-dns-synthesize.c
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@ -186,6 +186,7 @@ static int answer_add_addresses_ptr(
unsigned n_addresses,
int af, const union in_addr_union *match) {
bool added = false;
unsigned j;
int r;
@ -215,9 +216,11 @@ static int answer_add_addresses_ptr(
r = dns_answer_add(*answer, rr, addresses[j].ifindex, DNS_ANSWER_AUTHENTICATED);
if (r < 0)
return r;
added = true;
}
return 0;
return added;
}
static int synthesize_system_hostname_rr(Manager *m, const DnsResourceKey *key, int ifindex, DnsAnswer **answer) {
@ -263,6 +266,7 @@ static int synthesize_system_hostname_rr(Manager *m, const DnsResourceKey *key,
static int synthesize_system_hostname_ptr(Manager *m, int af, const union in_addr_union *address, int ifindex, DnsAnswer **answer) {
_cleanup_free_ struct local_address *addresses = NULL;
bool added = false;
int n, r;
assert(m);
@ -290,18 +294,26 @@ static int synthesize_system_hostname_ptr(Manager *m, int af, const union in_add
if (r < 0)
return r;
return 0;
return 1;
}
n = local_addresses(m->rtnl, ifindex, af, &addresses);
if (n < 0)
if (n <= 0)
return n;
r = answer_add_addresses_ptr(answer, m->llmnr_hostname, addresses, n, af, address);
if (r < 0)
return r;
if (r > 0)
added = true;
return answer_add_addresses_ptr(answer, m->mdns_hostname, addresses, n, af, address);
r = answer_add_addresses_ptr(answer, m->mdns_hostname, addresses, n, af, address);
if (r < 0)
return r;
if (r > 0)
added = true;
return added;
}
static int synthesize_gateway_rr(Manager *m, const DnsResourceKey *key, int ifindex, DnsAnswer **answer) {
@ -335,7 +347,7 @@ static int synthesize_gateway_ptr(Manager *m, int af, const union in_addr_union
assert(answer);
n = local_gateways(m->rtnl, ifindex, af, &addresses);
if (n < 0)
if (n <= 0)
return n;
return answer_add_addresses_ptr(answer, "_gateway", addresses, n, af, address);
@ -396,14 +408,19 @@ int dns_synthesize_answer(
return log_error_errno(r, "Failed to synthesize localhost PTR RRs: %m");
} else if (dns_name_address(name, &af, &address) > 0) {
int v, w;
r = synthesize_system_hostname_ptr(m, af, &address, ifindex, &answer);
if (r < 0)
v = synthesize_system_hostname_ptr(m, af, &address, ifindex, &answer);
if (v < 0)
return log_error_errno(r, "Failed to synthesize system hostname PTR RR: %m");
r = synthesize_gateway_ptr(m, af, &address, ifindex, &answer);
if (r < 0)
w = synthesize_gateway_ptr(m, af, &address, ifindex, &answer);
if (w < 0)
return log_error_errno(r, "Failed to synthesize gateway hostname PTR RR: %m");
if (v == 0 && w == 0) /* This IP address is neither a local one nor a gateway */
continue;
} else
continue;