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Diffstat (limited to 'src/resolve/resolved-dns-packet.c')
-rw-r--r--src/resolve/resolved-dns-packet.c242
1 files changed, 199 insertions, 43 deletions
diff --git a/src/resolve/resolved-dns-packet.c b/src/resolve/resolved-dns-packet.c
index ea776f7916..14faf9e4ab 100644
--- a/src/resolve/resolved-dns-packet.c
+++ b/src/resolve/resolved-dns-packet.c
@@ -65,20 +65,18 @@ int dns_packet_new(DnsPacket **ret, DnsProtocol protocol, size_t mtu) {
return 0;
}
-int dns_packet_new_query(DnsPacket **ret, DnsProtocol protocol, size_t mtu, bool dnssec_checking_disabled) {
- DnsPacket *p;
- DnsPacketHeader *h;
- int r;
+void dns_packet_set_flags(DnsPacket *p, bool dnssec_checking_disabled, bool truncated) {
- assert(ret);
+ DnsPacketHeader *h;
- r = dns_packet_new(&p, protocol, mtu);
- if (r < 0)
- return r;
+ assert(p);
h = DNS_PACKET_HEADER(p);
- if (protocol == DNS_PROTOCOL_LLMNR)
+ switch(p->protocol) {
+ case DNS_PROTOCOL_LLMNR:
+ assert(!truncated);
+
h->flags = htobe16(DNS_PACKET_MAKE_FLAGS(0 /* qr */,
0 /* opcode */,
0 /* c */,
@@ -88,7 +86,23 @@ int dns_packet_new_query(DnsPacket **ret, DnsProtocol protocol, size_t mtu, bool
0 /* ad */,
0 /* cd */,
0 /* rcode */));
- else
+ break;
+
+ case DNS_PROTOCOL_MDNS:
+ h->flags = htobe16(DNS_PACKET_MAKE_FLAGS(0 /* qr */,
+ 0 /* opcode */,
+ 0 /* aa */,
+ truncated /* tc */,
+ 0 /* rd (ask for recursion) */,
+ 0 /* ra */,
+ 0 /* ad */,
+ 0 /* cd */,
+ 0 /* rcode */));
+ break;
+
+ default:
+ assert(!truncated);
+
h->flags = htobe16(DNS_PACKET_MAKE_FLAGS(0 /* qr */,
0 /* opcode */,
0 /* aa */,
@@ -98,6 +112,23 @@ int dns_packet_new_query(DnsPacket **ret, DnsProtocol protocol, size_t mtu, bool
0 /* ad */,
dnssec_checking_disabled /* cd */,
0 /* rcode */));
+ }
+}
+
+int dns_packet_new_query(DnsPacket **ret, DnsProtocol protocol, size_t mtu, bool dnssec_checking_disabled) {
+ DnsPacket *p;
+ int r;
+
+ assert(ret);
+
+ r = dns_packet_new(&p, protocol, mtu);
+ if (r < 0)
+ return r;
+
+ /* Always set the TC bit to 0 initially.
+ * If there are multiple packets later, we'll update the bit shortly before sending.
+ */
+ dns_packet_set_flags(p, dnssec_checking_disabled, false);
*ret = p;
return 0;
@@ -122,6 +153,7 @@ static void dns_packet_free(DnsPacket *p) {
dns_question_unref(p->question);
dns_answer_unref(p->answer);
+ dns_resource_record_unref(p->opt);
while ((s = hashmap_steal_first_key(p->names)))
free(s);
@@ -139,6 +171,8 @@ DnsPacket *dns_packet_unref(DnsPacket *p) {
assert(p->n_ref > 0);
+ dns_packet_unref(p->more);
+
if (p->n_ref == 1)
dns_packet_free(p);
else
@@ -175,6 +209,7 @@ int dns_packet_validate_reply(DnsPacket *p) {
return -EBADMSG;
switch (p->protocol) {
+
case DNS_PROTOCOL_LLMNR:
/* RFC 4795, Section 2.1.1. says to discard all replies with QDCOUNT != 1 */
if (DNS_PACKET_QDCOUNT(p) != 1)
@@ -182,6 +217,13 @@ int dns_packet_validate_reply(DnsPacket *p) {
break;
+ case DNS_PROTOCOL_MDNS:
+ /* RFC 6762, Section 18 */
+ if (DNS_PACKET_RCODE(p) != 0)
+ return -EBADMSG;
+
+ break;
+
default:
break;
}
@@ -208,6 +250,7 @@ int dns_packet_validate_query(DnsPacket *p) {
return -EBADMSG;
switch (p->protocol) {
+
case DNS_PROTOCOL_LLMNR:
/* RFC 4795, Section 2.1.1. says to discard all queries with QDCOUNT != 1 */
if (DNS_PACKET_QDCOUNT(p) != 1)
@@ -223,6 +266,18 @@ int dns_packet_validate_query(DnsPacket *p) {
break;
+ case DNS_PROTOCOL_MDNS:
+ /* RFC 6762, Section 18 */
+ if (DNS_PACKET_AA(p) != 0 ||
+ DNS_PACKET_RD(p) != 0 ||
+ DNS_PACKET_RA(p) != 0 ||
+ DNS_PACKET_AD(p) != 0 ||
+ DNS_PACKET_CD(p) != 0 ||
+ DNS_PACKET_RCODE(p) != 0)
+ return -EBADMSG;
+
+ break;
+
default:
break;
}
@@ -383,10 +438,15 @@ int dns_packet_append_raw_string(DnsPacket *p, const void *s, size_t size, size_
return 0;
}
-int dns_packet_append_label(DnsPacket *p, const char *d, size_t l, size_t *start) {
+int dns_packet_append_label(DnsPacket *p, const char *d, size_t l, bool canonical_candidate, size_t *start) {
uint8_t *w;
int r;
+ /* Append a label to a packet. Optionally, does this in DNSSEC
+ * canonical form, if this label is marked as a candidate for
+ * it, and the canonical form logic is enabled for the
+ * packet */
+
assert(p);
assert(d);
@@ -399,7 +459,7 @@ int dns_packet_append_label(DnsPacket *p, const char *d, size_t l, size_t *start
*(w++) = (uint8_t) l;
- if (p->canonical_form) {
+ if (p->canonical_form && canonical_candidate) {
size_t i;
/* Generate in canonical form, as defined by DNSSEC
@@ -424,6 +484,7 @@ int dns_packet_append_name(
DnsPacket *p,
const char *name,
bool allow_compression,
+ bool canonical_candidate,
size_t *start) {
size_t saved_size;
@@ -478,7 +539,7 @@ int dns_packet_append_name(
if (k > 0)
r = k;
- r = dns_packet_append_label(p, label, r, &n);
+ r = dns_packet_append_label(p, label, r, canonical_candidate, &n);
if (r < 0)
goto fail;
@@ -519,7 +580,7 @@ int dns_packet_append_key(DnsPacket *p, const DnsResourceKey *k, size_t *start)
saved_size = p->size;
- r = dns_packet_append_name(p, DNS_RESOURCE_KEY_NAME(k), true, NULL);
+ r = dns_packet_append_name(p, DNS_RESOURCE_KEY_NAME(k), true, true, NULL);
if (r < 0)
goto fail;
@@ -541,7 +602,7 @@ fail:
return r;
}
-static int dns_packet_append_type_window(DnsPacket *p, uint8_t window, uint8_t length, uint8_t *types, size_t *start) {
+static int dns_packet_append_type_window(DnsPacket *p, uint8_t window, uint8_t length, const uint8_t *types, size_t *start) {
size_t saved_size;
int r;
@@ -598,15 +659,16 @@ static int dns_packet_append_types(DnsPacket *p, Bitmap *types, size_t *start) {
}
window = n >> 8;
-
entry = n & 255;
bitmaps[entry / 8] |= 1 << (7 - (entry % 8));
}
- r = dns_packet_append_type_window(p, window, entry / 8 + 1, bitmaps, NULL);
- if (r < 0)
- goto fail;
+ if (bitmaps[entry / 8] != 0) {
+ r = dns_packet_append_type_window(p, window, entry / 8 + 1, bitmaps, NULL);
+ if (r < 0)
+ goto fail;
+ }
if (start)
*start = saved_size;
@@ -707,14 +769,14 @@ int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *star
if (r < 0)
goto fail;
- r = dns_packet_append_name(p, rr->srv.name, true, NULL);
+ r = dns_packet_append_name(p, rr->srv.name, true, false, NULL);
break;
case DNS_TYPE_PTR:
case DNS_TYPE_NS:
case DNS_TYPE_CNAME:
case DNS_TYPE_DNAME:
- r = dns_packet_append_name(p, rr->ptr.name, true, NULL);
+ r = dns_packet_append_name(p, rr->ptr.name, true, false, NULL);
break;
case DNS_TYPE_HINFO:
@@ -757,11 +819,11 @@ int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *star
break;
case DNS_TYPE_SOA:
- r = dns_packet_append_name(p, rr->soa.mname, true, NULL);
+ r = dns_packet_append_name(p, rr->soa.mname, true, false, NULL);
if (r < 0)
goto fail;
- r = dns_packet_append_name(p, rr->soa.rname, true, NULL);
+ r = dns_packet_append_name(p, rr->soa.rname, true, false, NULL);
if (r < 0)
goto fail;
@@ -789,7 +851,7 @@ int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *star
if (r < 0)
goto fail;
- r = dns_packet_append_name(p, rr->mx.exchange, true, NULL);
+ r = dns_packet_append_name(p, rr->mx.exchange, true, false, NULL);
break;
case DNS_TYPE_LOC:
@@ -893,7 +955,7 @@ int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *star
if (r < 0)
goto fail;
- r = dns_packet_append_name(p, rr->rrsig.signer, false, NULL);
+ r = dns_packet_append_name(p, rr->rrsig.signer, false, true, NULL);
if (r < 0)
goto fail;
@@ -901,7 +963,7 @@ int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *star
break;
case DNS_TYPE_NSEC:
- r = dns_packet_append_name(p, rr->nsec.next_domain_name, false, NULL);
+ r = dns_packet_append_name(p, rr->nsec.next_domain_name, false, false, NULL);
if (r < 0)
goto fail;
@@ -910,6 +972,7 @@ int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *star
goto fail;
break;
+
case DNS_TYPE_NSEC3:
r = dns_packet_append_uint8(p, rr->nsec3.algorithm, NULL);
if (r < 0)
@@ -944,6 +1007,8 @@ int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *star
goto fail;
break;
+
+ case DNS_TYPE_OPT:
case _DNS_TYPE_INVALID: /* unparseable */
default:
@@ -1390,8 +1455,9 @@ fail:
return r;
}
-int dns_packet_read_key(DnsPacket *p, DnsResourceKey **ret, size_t *start) {
+int dns_packet_read_key(DnsPacket *p, DnsResourceKey **ret, bool *ret_cache_flush, size_t *start) {
_cleanup_free_ char *name = NULL;
+ bool cache_flush = false;
uint16_t class, type;
DnsResourceKey *key;
size_t saved_rindex;
@@ -1414,6 +1480,15 @@ int dns_packet_read_key(DnsPacket *p, DnsResourceKey **ret, size_t *start) {
if (r < 0)
goto fail;
+ if (p->protocol == DNS_PROTOCOL_MDNS) {
+ /* See RFC6762, Section 10.2 */
+
+ if (type != DNS_TYPE_OPT && (class & MDNS_RR_CACHE_FLUSH)) {
+ class &= ~MDNS_RR_CACHE_FLUSH;
+ cache_flush = true;
+ }
+ }
+
key = dns_resource_key_new_consume(class, type, name);
if (!key) {
r = -ENOMEM;
@@ -1423,6 +1498,8 @@ int dns_packet_read_key(DnsPacket *p, DnsResourceKey **ret, size_t *start) {
name = NULL;
*ret = key;
+ if (ret_cache_flush)
+ *ret_cache_flush = cache_flush;
if (start)
*start = saved_rindex;
@@ -1438,11 +1515,12 @@ static bool loc_size_ok(uint8_t size) {
return m <= 9 && e <= 9 && (m > 0 || e == 0);
}
-int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start) {
+int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, bool *ret_cache_flush, size_t *start) {
_cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
_cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
size_t saved_rindex, offset;
uint16_t rdlength;
+ bool cache_flush;
int r;
assert(p);
@@ -1450,12 +1528,12 @@ int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start) {
saved_rindex = p->rindex;
- r = dns_packet_read_key(p, &key, NULL);
+ r = dns_packet_read_key(p, &key, &cache_flush, NULL);
if (r < 0)
goto fail;
- if (key->class == DNS_CLASS_ANY ||
- key->type == DNS_TYPE_ANY) {
+ if (!dns_class_is_valid_rr(key->class)||
+ !dns_type_is_valid_rr(key->type)) {
r = -EBADMSG;
goto fail;
}
@@ -1503,10 +1581,6 @@ int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start) {
r = dns_packet_read_name(p, &rr->ptr.name, true, NULL);
break;
- case DNS_TYPE_OPT: /* we only care about the header */
- r = 0;
- break;
-
case DNS_TYPE_HINFO:
r = dns_packet_read_string(p, &rr->hinfo.cpu, NULL);
if (r < 0)
@@ -1684,6 +1758,7 @@ int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start) {
}
break;
+
case DNS_TYPE_SSHFP:
r = dns_packet_read_uint8(p, &rr->sshfp.algorithm, NULL);
if (r < 0)
@@ -1778,8 +1853,16 @@ int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start) {
break;
- case DNS_TYPE_NSEC:
- r = dns_packet_read_name(p, &rr->nsec.next_domain_name, false, NULL);
+ case DNS_TYPE_NSEC: {
+
+ /*
+ * RFC6762, section 18.14 explictly states mDNS should use name compression.
+ * This contradicts RFC3845, section 2.1.1
+ */
+
+ bool allow_compressed = p->protocol == DNS_PROTOCOL_MDNS;
+
+ r = dns_packet_read_name(p, &rr->nsec.next_domain_name, allow_compressed, NULL);
if (r < 0)
goto fail;
@@ -1792,7 +1875,7 @@ int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start) {
* without the NSEC bit set. */
break;
-
+ }
case DNS_TYPE_NSEC3: {
uint8_t size;
@@ -1838,6 +1921,8 @@ int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start) {
break;
}
+
+ case DNS_TYPE_OPT: /* we only care about the header of OPT for now. */
default:
unparseable:
r = dns_packet_read_memdup(p, rdlength, &rr->generic.data, &rr->generic.size, NULL);
@@ -1855,6 +1940,8 @@ int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start) {
*ret = rr;
rr = NULL;
+ if (ret_cache_flush)
+ *ret_cache_flush = cache_flush;
if (start)
*start = saved_rindex;
@@ -1887,11 +1974,22 @@ int dns_packet_extract(DnsPacket *p) {
for (i = 0; i < n; i++) {
_cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
+ bool cache_flush;
- r = dns_packet_read_key(p, &key, NULL);
+ r = dns_packet_read_key(p, &key, &cache_flush, NULL);
if (r < 0)
goto finish;
+ if (cache_flush) {
+ r = -EBADMSG;
+ goto finish;
+ }
+
+ if (!dns_type_is_valid_query(key->type)) {
+ r = -EBADMSG;
+ goto finish;
+ }
+
r = dns_question_add(question, key);
if (r < 0)
goto finish;
@@ -1908,14 +2006,48 @@ int dns_packet_extract(DnsPacket *p) {
for (i = 0; i < n; i++) {
_cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
+ bool cache_flush;
- r = dns_packet_read_rr(p, &rr, NULL);
+ r = dns_packet_read_rr(p, &rr, &cache_flush, NULL);
if (r < 0)
goto finish;
- r = dns_answer_add(answer, rr, p->ifindex);
- if (r < 0)
- goto finish;
+ if (rr->key->type == DNS_TYPE_OPT) {
+
+ if (!dns_name_is_root(DNS_RESOURCE_KEY_NAME(rr->key))) {
+ r = -EBADMSG;
+ goto finish;
+ }
+
+ /* The OPT RR is only valid in the Additional section */
+ if (i < DNS_PACKET_ANCOUNT(p) + DNS_PACKET_NSCOUNT(p)) {
+ r = -EBADMSG;
+ goto finish;
+ }
+
+ /* Two OPT RRs? */
+ if (p->opt) {
+ r = -EBADMSG;
+ goto finish;
+ }
+
+ p->opt = dns_resource_record_ref(rr);
+ } else {
+
+ /* According to RFC 4795, section
+ * 2.9. only the RRs from the Answer
+ * section shall be cached. Hence mark
+ * only those RRs as cacheable by
+ * default, but not the ones from the
+ * Additional or Authority
+ * sections. */
+
+ r = dns_answer_add(answer, rr, p->ifindex,
+ (i < DNS_PACKET_ANCOUNT(p) ? DNS_ANSWER_CACHEABLE : 0) |
+ (p->protocol == DNS_PROTOCOL_MDNS && !cache_flush ? DNS_ANSWER_SHARED_OWNER : 0));
+ if (r < 0)
+ goto finish;
+ }
}
}
@@ -1934,6 +2066,30 @@ finish:
return r;
}
+int dns_packet_is_reply_for(DnsPacket *p, const DnsResourceKey *key) {
+ int r;
+
+ assert(p);
+ assert(key);
+
+ /* Checks if the specified packet is a reply for the specified
+ * key and the specified key is the only one in the question
+ * section. */
+
+ if (DNS_PACKET_QR(p) != 1)
+ return 0;
+
+ /* Let's unpack the packet, if that hasn't happened yet. */
+ r = dns_packet_extract(p);
+ if (r < 0)
+ return r;
+
+ if (p->question->n_keys != 1)
+ return 0;
+
+ return dns_resource_key_equal(p->question->keys[0], key);
+}
+
static const char* const dns_rcode_table[_DNS_RCODE_MAX_DEFINED] = {
[DNS_RCODE_SUCCESS] = "SUCCESS",
[DNS_RCODE_FORMERR] = "FORMERR",
generated by cgit v1.2.3-54-g00ecf (git 2.45.2) at 2024-11-05 16:29:54 +0000