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-rw-r--r--src/resolve/resolved-dns-packet.c1318
1 files changed, 911 insertions, 407 deletions
diff --git a/src/resolve/resolved-dns-packet.c b/src/resolve/resolved-dns-packet.c
index b1cde4ab35..337a8c473f 100644
--- a/src/resolve/resolved-dns-packet.c
+++ b/src/resolve/resolved-dns-packet.c
@@ -1,5 +1,3 @@
-/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
-
/***
This file is part of systemd.
@@ -19,12 +17,29 @@
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
-#include "utf8.h"
-#include "util.h"
-#include "strv.h"
-#include "unaligned.h"
+#include "alloc-util.h"
#include "dns-domain.h"
#include "resolved-dns-packet.h"
+#include "string-table.h"
+#include "strv.h"
+#include "unaligned.h"
+#include "utf8.h"
+#include "util.h"
+
+#define EDNS0_OPT_DO (1<<15)
+
+typedef struct DnsPacketRewinder {
+ DnsPacket *packet;
+ size_t saved_rindex;
+} DnsPacketRewinder;
+
+static void rewind_dns_packet(DnsPacketRewinder *rewinder) {
+ if (rewinder->packet)
+ dns_packet_rewind(rewinder->packet, rewinder->saved_rindex);
+}
+
+#define INIT_REWINDER(rewinder, p) do { rewinder.packet = p; rewinder.saved_rindex = p->rindex; } while (0)
+#define CANCEL_REWINDER(rewinder) do { rewinder.packet = NULL; } while (0)
int dns_packet_new(DnsPacket **ret, DnsProtocol protocol, size_t mtu) {
DnsPacket *p;
@@ -54,6 +69,7 @@ int dns_packet_new(DnsPacket **ret, DnsProtocol protocol, size_t mtu) {
p->size = p->rindex = DNS_PACKET_HEADER_SIZE;
p->allocated = a;
p->protocol = protocol;
+ p->opt_start = p->opt_size = (size_t) -1;
p->n_ref = 1;
*ret = p;
@@ -61,20 +77,18 @@ 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) {
- 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 */,
@@ -84,7 +98,23 @@ int dns_packet_new_query(DnsPacket **ret, DnsProtocol protocol, size_t mtu) {
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 */,
@@ -92,8 +122,25 @@ int dns_packet_new_query(DnsPacket **ret, DnsProtocol protocol, size_t mtu) {
1 /* rd (ask for recursion) */,
0 /* ra */,
0 /* ad */,
- 0 /* cd */,
+ 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;
@@ -104,6 +151,8 @@ DnsPacket *dns_packet_ref(DnsPacket *p) {
if (!p)
return NULL;
+ assert(!p->on_stack);
+
assert(p->n_ref > 0);
p->n_ref++;
return p;
@@ -116,13 +165,16 @@ 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);
hashmap_free(p->names);
free(p->_data);
- free(p);
+
+ if (!p->on_stack)
+ free(p);
}
DnsPacket *dns_packet_unref(DnsPacket *p) {
@@ -131,6 +183,8 @@ 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
@@ -167,6 +221,7 @@ 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)
@@ -174,6 +229,13 @@ 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;
}
@@ -200,7 +262,9 @@ int dns_packet_validate_query(DnsPacket *p) {
return -EBADMSG;
switch (p->protocol) {
+
case DNS_PROTOCOL_LLMNR:
+ case DNS_PROTOCOL_DNS:
/* RFC 4795, Section 2.1.1. says to discard all queries with QDCOUNT != 1 */
if (DNS_PACKET_QDCOUNT(p) != 1)
return -EBADMSG;
@@ -215,6 +279,18 @@ 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;
}
@@ -265,7 +341,7 @@ static int dns_packet_extend(DnsPacket *p, size_t add, void **ret, size_t *start
return 0;
}
-static void dns_packet_truncate(DnsPacket *p, size_t sz) {
+void dns_packet_truncate(DnsPacket *p, size_t sz) {
Iterator i;
char *s;
void *n;
@@ -275,7 +351,7 @@ static void dns_packet_truncate(DnsPacket *p, size_t sz) {
if (p->size <= sz)
return;
- HASHMAP_FOREACH_KEY(s, n, p->names, i) {
+ HASHMAP_FOREACH_KEY(n, s, p->names, i) {
if (PTR_TO_SIZE(n) < sz)
continue;
@@ -347,62 +423,93 @@ int dns_packet_append_uint32(DnsPacket *p, uint32_t v, size_t *start) {
}
int dns_packet_append_string(DnsPacket *p, const char *s, size_t *start) {
+ assert(p);
+ assert(s);
+
+ return dns_packet_append_raw_string(p, s, strlen(s), start);
+}
+
+int dns_packet_append_raw_string(DnsPacket *p, const void *s, size_t size, size_t *start) {
void *d;
- size_t l;
int r;
assert(p);
- assert(s);
+ assert(s || size == 0);
- l = strlen(s);
- if (l > 255)
+ if (size > 255)
return -E2BIG;
- r = dns_packet_extend(p, 1 + l, &d, start);
+ r = dns_packet_extend(p, 1 + size, &d, start);
if (r < 0)
return r;
- ((uint8_t*) d)[0] = (uint8_t) l;
- memcpy(((uint8_t*) d) + 1, s, l);
+ ((uint8_t*) d)[0] = (uint8_t) size;
+
+ memcpy_safe(((uint8_t*) d) + 1, s, size);
return 0;
}
-int dns_packet_append_label(DnsPacket *p, const char *d, size_t l, size_t *start) {
- void *w;
+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);
if (l > DNS_LABEL_MAX)
return -E2BIG;
- r = dns_packet_extend(p, 1 + l, &w, start);
+ r = dns_packet_extend(p, 1 + l, (void**) &w, start);
if (r < 0)
return r;
- ((uint8_t*) w)[0] = (uint8_t) l;
- memcpy(((uint8_t*) w) + 1, d, l);
+ *(w++) = (uint8_t) l;
+
+ if (p->canonical_form && canonical_candidate) {
+ size_t i;
+
+ /* Generate in canonical form, as defined by DNSSEC
+ * RFC 4034, Section 6.2, i.e. all lower-case. */
+
+ for (i = 0; i < l; i++)
+ w[i] = (uint8_t) ascii_tolower(d[i]);
+ } else
+ /* Otherwise, just copy the string unaltered. This is
+ * essential for DNS-SD, where the casing of labels
+ * matters and needs to be retained. */
+ memcpy(w, d, l);
return 0;
}
-int dns_packet_append_name(DnsPacket *p, const char *name,
- bool allow_compression, size_t *start) {
+int dns_packet_append_name(
+ DnsPacket *p,
+ const char *name,
+ bool allow_compression,
+ bool canonical_candidate,
+ size_t *start) {
+
size_t saved_size;
int r;
assert(p);
assert(name);
+ if (p->refuse_compression)
+ allow_compression = false;
+
saved_size = p->size;
- while (*name) {
- _cleanup_free_ char *s = NULL;
+ while (!dns_name_is_root(name)) {
+ const char *z = name;
char label[DNS_LABEL_MAX];
size_t n = 0;
- int k;
if (allow_compression)
n = PTR_TO_SIZE(hashmap_get(p->names, name));
@@ -418,32 +525,23 @@ int dns_packet_append_name(DnsPacket *p, const char *name,
}
}
- s = strdup(name);
- if (!s) {
- r = -ENOMEM;
- goto fail;
- }
-
r = dns_label_unescape(&name, label, sizeof(label));
if (r < 0)
goto fail;
- if (p->protocol == DNS_PROTOCOL_DNS)
- k = dns_label_apply_idna(label, r, label, sizeof(label));
- else
- k = dns_label_undo_idna(label, r, label, sizeof(label));
- if (k < 0) {
- r = k;
- goto fail;
- }
- 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;
if (allow_compression) {
+ _cleanup_free_ char *s = NULL;
+
+ s = strdup(z);
+ if (!s) {
+ r = -ENOMEM;
+ goto fail;
+ }
+
r = hashmap_ensure_allocated(&p->names, &dns_name_hash_ops);
if (r < 0)
goto fail;
@@ -480,7 +578,7 @@ 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;
@@ -502,15 +600,13 @@ 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;
assert(p);
assert(types);
-
- if (length == 0)
- return 0;
+ assert(length > 0);
saved_size = p->size;
@@ -538,56 +634,166 @@ fail:
static int dns_packet_append_types(DnsPacket *p, Bitmap *types, size_t *start) {
Iterator i;
uint8_t window = 0;
- uint8_t len = 0;
+ uint8_t entry = 0;
uint8_t bitmaps[32] = {};
unsigned n;
size_t saved_size;
int r;
assert(p);
- assert(types);
saved_size = p->size;
BITMAP_FOREACH(n, types, i) {
- uint8_t entry;
-
assert(n <= 0xffff);
- if ((n << 8) != window) {
- r = dns_packet_append_type_window(p, window, len, bitmaps, NULL);
+ if ((n >> 8) != window && bitmaps[entry / 8] != 0) {
+ r = dns_packet_append_type_window(p, window, entry / 8 + 1, bitmaps, NULL);
if (r < 0)
goto fail;
- if (len > 0) {
- len = 0;
- zero(bitmaps);
- }
+ zero(bitmaps);
}
- window = n << 8;
- len ++;
-
+ window = n >> 8;
entry = n & 255;
bitmaps[entry / 8] |= 1 << (7 - (entry % 8));
}
- r = dns_packet_append_type_window(p, window, len, bitmaps, NULL);
+ 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;
+
+ return 0;
+fail:
+ dns_packet_truncate(p, saved_size);
+ return r;
+}
+
+/* Append the OPT pseudo-RR described in RFC6891 */
+int dns_packet_append_opt(DnsPacket *p, uint16_t max_udp_size, bool edns0_do, int rcode, size_t *start) {
+ size_t saved_size;
+ int r;
+
+ assert(p);
+ /* we must never advertise supported packet size smaller than the legacy max */
+ assert(max_udp_size >= DNS_PACKET_UNICAST_SIZE_MAX);
+ assert(rcode >= 0);
+ assert(rcode <= _DNS_RCODE_MAX);
+
+ if (p->opt_start != (size_t) -1)
+ return -EBUSY;
+
+ assert(p->opt_size == (size_t) -1);
+
+ saved_size = p->size;
+
+ /* empty name */
+ r = dns_packet_append_uint8(p, 0, NULL);
+ if (r < 0)
+ return r;
+
+ /* type */
+ r = dns_packet_append_uint16(p, DNS_TYPE_OPT, NULL);
if (r < 0)
goto fail;
+ /* class: maximum udp packet that can be received */
+ r = dns_packet_append_uint16(p, max_udp_size, NULL);
+ if (r < 0)
+ goto fail;
+
+ /* extended RCODE and VERSION */
+ r = dns_packet_append_uint16(p, ((uint16_t) rcode & 0x0FF0) << 4, NULL);
+ if (r < 0)
+ goto fail;
+
+ /* flags: DNSSEC OK (DO), see RFC3225 */
+ r = dns_packet_append_uint16(p, edns0_do ? EDNS0_OPT_DO : 0, NULL);
+ if (r < 0)
+ goto fail;
+
+ /* RDLENGTH */
+ if (edns0_do && !DNS_PACKET_QR(p)) {
+ /* If DO is on and this is not a reply, also append RFC6975 Algorithm data */
+
+ static const uint8_t rfc6975[] = {
+
+ 0, 5, /* OPTION_CODE: DAU */
+ 0, 6, /* LIST_LENGTH */
+ DNSSEC_ALGORITHM_RSASHA1,
+ DNSSEC_ALGORITHM_RSASHA1_NSEC3_SHA1,
+ DNSSEC_ALGORITHM_RSASHA256,
+ DNSSEC_ALGORITHM_RSASHA512,
+ DNSSEC_ALGORITHM_ECDSAP256SHA256,
+ DNSSEC_ALGORITHM_ECDSAP384SHA384,
+
+ 0, 6, /* OPTION_CODE: DHU */
+ 0, 3, /* LIST_LENGTH */
+ DNSSEC_DIGEST_SHA1,
+ DNSSEC_DIGEST_SHA256,
+ DNSSEC_DIGEST_SHA384,
+
+ 0, 7, /* OPTION_CODE: N3U */
+ 0, 1, /* LIST_LENGTH */
+ NSEC3_ALGORITHM_SHA1,
+ };
+
+ r = dns_packet_append_uint16(p, sizeof(rfc6975), NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_blob(p, rfc6975, sizeof(rfc6975), NULL);
+ } else
+ r = dns_packet_append_uint16(p, 0, NULL);
+ if (r < 0)
+ goto fail;
+
+ DNS_PACKET_HEADER(p)->arcount = htobe16(DNS_PACKET_ARCOUNT(p) + 1);
+
+ p->opt_start = saved_size;
+ p->opt_size = p->size - saved_size;
+
if (start)
*start = saved_size;
return 0;
+
fail:
dns_packet_truncate(p, saved_size);
return r;
}
-int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *start) {
- size_t saved_size, rdlength_offset, end, rdlength;
+int dns_packet_truncate_opt(DnsPacket *p) {
+ assert(p);
+
+ if (p->opt_start == (size_t) -1) {
+ assert(p->opt_size == (size_t) -1);
+ return 0;
+ }
+
+ assert(p->opt_size != (size_t) -1);
+ assert(DNS_PACKET_ARCOUNT(p) > 0);
+
+ if (p->opt_start + p->opt_size != p->size)
+ return -EBUSY;
+
+ dns_packet_truncate(p, p->opt_start);
+ DNS_PACKET_HEADER(p)->arcount = htobe16(DNS_PACKET_ARCOUNT(p) - 1);
+ p->opt_start = p->opt_size = (size_t) -1;
+
+ return 1;
+}
+
+int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *start, size_t *rdata_start) {
+
+ size_t saved_size, rdlength_offset, end, rdlength, rds;
int r;
assert(p);
@@ -608,6 +814,8 @@ int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *star
if (r < 0)
goto fail;
+ rds = p->size - saved_size;
+
switch (rr->unparseable ? _DNS_TYPE_INVALID : rr->key->type) {
case DNS_TYPE_SRV:
@@ -623,14 +831,14 @@ 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:
@@ -642,19 +850,20 @@ int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *star
break;
case DNS_TYPE_SPF: /* exactly the same as TXT */
- case DNS_TYPE_TXT: {
- char **s;
+ case DNS_TYPE_TXT:
- if (strv_isempty(rr->txt.strings)) {
+ if (!rr->txt.items) {
/* RFC 6763, section 6.1 suggests to generate
* single empty string for an empty array. */
- r = dns_packet_append_string(p, "", NULL);
+ r = dns_packet_append_raw_string(p, NULL, 0, NULL);
if (r < 0)
goto fail;
} else {
- STRV_FOREACH(s, rr->txt.strings) {
- r = dns_packet_append_string(p, *s, NULL);
+ DnsTxtItem *i;
+
+ LIST_FOREACH(items, i, rr->txt.items) {
+ r = dns_packet_append_raw_string(p, i->data, i->length, NULL);
if (r < 0)
goto fail;
}
@@ -662,7 +871,6 @@ int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *star
r = 0;
break;
- }
case DNS_TYPE_A:
r = dns_packet_append_blob(p, &rr->a.in_addr, sizeof(struct in_addr), NULL);
@@ -673,11 +881,11 @@ 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;
@@ -705,7 +913,7 @@ 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:
@@ -761,15 +969,15 @@ int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *star
if (r < 0)
goto fail;
- r = dns_packet_append_blob(p, rr->sshfp.key, rr->sshfp.key_size, NULL);
+ r = dns_packet_append_blob(p, rr->sshfp.fingerprint, rr->sshfp.fingerprint_size, NULL);
break;
case DNS_TYPE_DNSKEY:
- r = dns_packet_append_uint16(p, dnskey_to_flags(rr), NULL);
+ r = dns_packet_append_uint16(p, rr->dnskey.flags, NULL);
if (r < 0)
goto fail;
- r = dns_packet_append_uint8(p, 3u, NULL);
+ r = dns_packet_append_uint8(p, rr->dnskey.protocol, NULL);
if (r < 0)
goto fail;
@@ -809,7 +1017,7 @@ 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;
@@ -817,7 +1025,7 @@ 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;
@@ -826,6 +1034,7 @@ 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)
@@ -860,10 +1069,41 @@ int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *star
goto fail;
break;
+
+ case DNS_TYPE_TLSA:
+ r = dns_packet_append_uint8(p, rr->tlsa.cert_usage, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_uint8(p, rr->tlsa.selector, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_uint8(p, rr->tlsa.matching_type, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_blob(p, rr->tlsa.data, rr->tlsa.data_size, NULL);
+ break;
+
+ case DNS_TYPE_CAA:
+ r = dns_packet_append_uint8(p, rr->caa.flags, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_string(p, rr->caa.tag, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_blob(p, rr->caa.value, rr->caa.value_size, NULL);
+ break;
+
+ case DNS_TYPE_OPT:
+ case DNS_TYPE_OPENPGPKEY:
case _DNS_TYPE_INVALID: /* unparseable */
default:
- r = dns_packet_append_blob(p, rr->generic.data, rr->generic.size, NULL);
+ r = dns_packet_append_blob(p, rr->generic.data, rr->generic.data_size, NULL);
break;
}
if (r < 0)
@@ -872,7 +1112,7 @@ int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *star
/* Let's calculate the actual data size and update the field */
rdlength = p->size - rdlength_offset - sizeof(uint16_t);
if (rdlength > 0xFFFF) {
- r = ENOSPC;
+ r = -ENOSPC;
goto fail;
}
@@ -886,6 +1126,9 @@ int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *star
if (start)
*start = saved_size;
+ if (rdata_start)
+ *rdata_start = rds;
+
return 0;
fail:
@@ -893,6 +1136,35 @@ fail:
return r;
}
+int dns_packet_append_question(DnsPacket *p, DnsQuestion *q) {
+ DnsResourceKey *key;
+ int r;
+
+ assert(p);
+
+ DNS_QUESTION_FOREACH(key, q) {
+ r = dns_packet_append_key(p, key, NULL);
+ if (r < 0)
+ return r;
+ }
+
+ return 0;
+}
+
+int dns_packet_append_answer(DnsPacket *p, DnsAnswer *a) {
+ DnsResourceRecord *rr;
+ int r;
+
+ assert(p);
+
+ DNS_ANSWER_FOREACH(rr, a) {
+ r = dns_packet_append_rr(p, rr, NULL, NULL);
+ if (r < 0)
+ return r;
+ }
+
+ return 0;
+}
int dns_packet_read(DnsPacket *p, size_t sz, const void **ret, size_t *start) {
assert(p);
@@ -933,6 +1205,42 @@ int dns_packet_read_blob(DnsPacket *p, void *d, size_t sz, size_t *start) {
return 0;
}
+static int dns_packet_read_memdup(
+ DnsPacket *p, size_t size,
+ void **ret, size_t *ret_size,
+ size_t *ret_start) {
+
+ const void *src;
+ size_t start;
+ int r;
+
+ assert(p);
+ assert(ret);
+
+ r = dns_packet_read(p, size, &src, &start);
+ if (r < 0)
+ return r;
+
+ if (size <= 0)
+ *ret = NULL;
+ else {
+ void *copy;
+
+ copy = memdup(src, size);
+ if (!copy)
+ return -ENOMEM;
+
+ *ret = copy;
+ }
+
+ if (ret_size)
+ *ret_size = size;
+ if (ret_start)
+ *ret_start = start;
+
+ return 0;
+}
+
int dns_packet_read_uint8(DnsPacket *p, uint8_t *ret, size_t *start) {
const void *d;
int r;
@@ -978,56 +1286,77 @@ int dns_packet_read_uint32(DnsPacket *p, uint32_t *ret, size_t *start) {
}
int dns_packet_read_string(DnsPacket *p, char **ret, size_t *start) {
- size_t saved_rindex;
+ _cleanup_(rewind_dns_packet) DnsPacketRewinder rewinder;
const void *d;
char *t;
uint8_t c;
int r;
assert(p);
-
- saved_rindex = p->rindex;
+ INIT_REWINDER(rewinder, p);
r = dns_packet_read_uint8(p, &c, NULL);
if (r < 0)
- goto fail;
+ return r;
r = dns_packet_read(p, c, &d, NULL);
if (r < 0)
- goto fail;
+ return r;
- if (memchr(d, 0, c)) {
- r = -EBADMSG;
- goto fail;
- }
+ if (memchr(d, 0, c))
+ return -EBADMSG;
t = strndup(d, c);
- if (!t) {
- r = -ENOMEM;
- goto fail;
- }
+ if (!t)
+ return -ENOMEM;
if (!utf8_is_valid(t)) {
free(t);
- r = -EBADMSG;
- goto fail;
+ return -EBADMSG;
}
*ret = t;
if (start)
- *start = saved_rindex;
+ *start = rewinder.saved_rindex;
+ CANCEL_REWINDER(rewinder);
return 0;
+}
-fail:
- dns_packet_rewind(p, saved_rindex);
- return r;
+int dns_packet_read_raw_string(DnsPacket *p, const void **ret, size_t *size, size_t *start) {
+ _cleanup_(rewind_dns_packet) DnsPacketRewinder rewinder;
+ uint8_t c;
+ int r;
+
+ assert(p);
+ INIT_REWINDER(rewinder, p);
+
+ r = dns_packet_read_uint8(p, &c, NULL);
+ if (r < 0)
+ return r;
+
+ r = dns_packet_read(p, c, ret, NULL);
+ if (r < 0)
+ return r;
+
+ if (size)
+ *size = c;
+ if (start)
+ *start = rewinder.saved_rindex;
+ CANCEL_REWINDER(rewinder);
+
+ return 0;
}
-int dns_packet_read_name(DnsPacket *p, char **_ret,
- bool allow_compression, size_t *start) {
- size_t saved_rindex, after_rindex = 0, jump_barrier;
+int dns_packet_read_name(
+ DnsPacket *p,
+ char **_ret,
+ bool allow_compression,
+ size_t *start) {
+
+ _cleanup_(rewind_dns_packet) DnsPacketRewinder rewinder;
+ size_t after_rindex = 0, jump_barrier;
_cleanup_free_ char *ret = NULL;
size_t n = 0, allocated = 0;
bool first = true;
@@ -1035,44 +1364,42 @@ int dns_packet_read_name(DnsPacket *p, char **_ret,
assert(p);
assert(_ret);
-
- saved_rindex = p->rindex;
+ INIT_REWINDER(rewinder, p);
jump_barrier = p->rindex;
+ if (p->refuse_compression)
+ allow_compression = false;
+
for (;;) {
uint8_t c, d;
r = dns_packet_read_uint8(p, &c, NULL);
if (r < 0)
- goto fail;
+ return r;
if (c == 0)
/* End of name */
break;
else if (c <= 63) {
- _cleanup_free_ char *t = NULL;
const char *label;
/* Literal label */
r = dns_packet_read(p, c, (const void**) &label, NULL);
if (r < 0)
- goto fail;
-
- r = dns_label_escape(label, c, &t);
- if (r < 0)
- goto fail;
+ return r;
- if (!GREEDY_REALLOC(ret, allocated, n + !first + strlen(t) + 1)) {
- r = -ENOMEM;
- goto fail;
- }
+ if (!GREEDY_REALLOC(ret, allocated, n + !first + DNS_LABEL_ESCAPED_MAX))
+ return -ENOMEM;
- if (!first)
- ret[n++] = '.';
- else
+ if (first)
first = false;
+ else
+ ret[n++] = '.';
+
+ r = dns_label_escape(label, c, ret + n, DNS_LABEL_ESCAPED_MAX);
+ if (r < 0)
+ return r;
- memcpy(ret + n, t, r);
n += r;
continue;
} else if (allow_compression && (c & 0xc0) == 0xc0) {
@@ -1081,13 +1408,11 @@ int dns_packet_read_name(DnsPacket *p, char **_ret,
/* Pointer */
r = dns_packet_read_uint8(p, &d, NULL);
if (r < 0)
- goto fail;
+ return r;
ptr = (uint16_t) (c & ~0xc0) << 8 | (uint16_t) d;
- if (ptr < DNS_PACKET_HEADER_SIZE || ptr >= jump_barrier) {
- r = -EBADMSG;
- goto fail;
- }
+ if (ptr < DNS_PACKET_HEADER_SIZE || ptr >= jump_barrier)
+ return -EBADMSG;
if (after_rindex == 0)
after_rindex = p->rindex;
@@ -1095,16 +1420,12 @@ int dns_packet_read_name(DnsPacket *p, char **_ret,
/* Jumps are limited to a "prior occurrence" (RFC-1035 4.1.4) */
jump_barrier = ptr;
p->rindex = ptr;
- } else {
- r = -EBADMSG;
- goto fail;
- }
+ } else
+ return -EBADMSG;
}
- if (!GREEDY_REALLOC(ret, allocated, n + 1)) {
- r = -ENOMEM;
- goto fail;
- }
+ if (!GREEDY_REALLOC(ret, allocated, n + 1))
+ return -ENOMEM;
ret[n] = 0;
@@ -1115,54 +1436,51 @@ int dns_packet_read_name(DnsPacket *p, char **_ret,
ret = NULL;
if (start)
- *start = saved_rindex;
+ *start = rewinder.saved_rindex;
+ CANCEL_REWINDER(rewinder);
return 0;
-
-fail:
- dns_packet_rewind(p, saved_rindex);
- return r;
}
static int dns_packet_read_type_window(DnsPacket *p, Bitmap **types, size_t *start) {
uint8_t window;
uint8_t length;
const uint8_t *bitmap;
+ uint8_t bit = 0;
unsigned i;
bool found = false;
- size_t saved_rindex;
+ _cleanup_(rewind_dns_packet) DnsPacketRewinder rewinder;
int r;
assert(p);
assert(types);
-
- saved_rindex = p->rindex;
+ INIT_REWINDER(rewinder, p);
r = bitmap_ensure_allocated(types);
if (r < 0)
- goto fail;
+ return r;
r = dns_packet_read_uint8(p, &window, NULL);
if (r < 0)
- goto fail;
+ return r;
r = dns_packet_read_uint8(p, &length, NULL);
if (r < 0)
- goto fail;
+ return r;
if (length == 0 || length > 32)
return -EBADMSG;
r = dns_packet_read(p, length, (const void **)&bitmap, NULL);
if (r < 0)
- goto fail;
+ return r;
for (i = 0; i < length; i++) {
uint8_t bitmask = 1 << 7;
- uint8_t bit = 0;
if (!bitmap[i]) {
found = false;
+ bit += 8;
continue;
}
@@ -1172,15 +1490,18 @@ static int dns_packet_read_type_window(DnsPacket *p, Bitmap **types, size_t *sta
if (bitmap[i] & bitmask) {
uint16_t n;
- /* XXX: ignore pseudo-types? see RFC4034 section 4.1.2 */
n = (uint16_t) window << 8 | (uint16_t) bit;
+ /* Ignore pseudo-types. see RFC4034 section 4.1.2 */
+ if (dns_type_is_pseudo(n))
+ continue;
+
r = bitmap_set(*types, n);
if (r < 0)
- goto fail;
+ return r;
}
- bit ++;
+ bit++;
bitmask >>= 1;
}
}
@@ -1189,73 +1510,84 @@ static int dns_packet_read_type_window(DnsPacket *p, Bitmap **types, size_t *sta
return -EBADMSG;
if (start)
- *start = saved_rindex;
+ *start = rewinder.saved_rindex;
+ CANCEL_REWINDER(rewinder);
+
+ return 0;
+}
+
+static int dns_packet_read_type_windows(DnsPacket *p, Bitmap **types, size_t size, size_t *start) {
+ _cleanup_(rewind_dns_packet) DnsPacketRewinder rewinder;
+ int r;
+
+ INIT_REWINDER(rewinder, p);
+
+ while (p->rindex < rewinder.saved_rindex + size) {
+ r = dns_packet_read_type_window(p, types, NULL);
+ if (r < 0)
+ return r;
+
+ /* don't read past end of current RR */
+ if (p->rindex > rewinder.saved_rindex + size)
+ return -EBADMSG;
+ }
+
+ if (p->rindex != rewinder.saved_rindex + size)
+ return -EBADMSG;
+
+ if (start)
+ *start = rewinder.saved_rindex;
+ CANCEL_REWINDER(rewinder);
return 0;
-fail:
- dns_packet_rewind(p, saved_rindex);
- 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_(rewind_dns_packet) DnsPacketRewinder rewinder;
_cleanup_free_ char *name = NULL;
+ bool cache_flush = false;
uint16_t class, type;
DnsResourceKey *key;
- size_t saved_rindex;
int r;
assert(p);
assert(ret);
-
- saved_rindex = p->rindex;
+ INIT_REWINDER(rewinder, p);
r = dns_packet_read_name(p, &name, true, NULL);
if (r < 0)
- goto fail;
+ return r;
r = dns_packet_read_uint16(p, &type, NULL);
if (r < 0)
- goto fail;
+ return r;
r = dns_packet_read_uint16(p, &class, NULL);
if (r < 0)
- goto fail;
+ return r;
- key = dns_resource_key_new_consume(class, type, name);
- if (!key) {
- r = -ENOMEM;
- 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)
+ return -ENOMEM;
+
name = NULL;
*ret = key;
+ if (ret_cache_flush)
+ *ret_cache_flush = cache_flush;
if (start)
- *start = saved_rindex;
-
- return 0;
-fail:
- dns_packet_rewind(p, saved_rindex);
- return r;
-}
-
-static int dns_packet_read_public_key(DnsPacket *p, size_t length,
- void **dp, size_t *lengthp,
- size_t *start) {
- int r;
- const void *d;
- void *d2;
-
- r = dns_packet_read(p, length, &d, NULL);
- if (r < 0)
- return r;
-
- d2 = memdup(d, length);
- if (!d2)
- return -ENOMEM;
+ *start = rewinder.saved_rindex;
+ CANCEL_REWINDER(rewinder);
- *dp = d2;
- *lengthp = length;
return 0;
}
@@ -1265,58 +1597,46 @@ static bool loc_size_ok(uint8_t size) {
return m <= 9 && e <= 9 && (m > 0 || e == 0);
}
-static int dnskey_parse_flags(DnsResourceRecord *rr, uint16_t flags) {
- assert(rr);
-
- if (flags & ~(DNSKEY_FLAG_SEP | DNSKEY_FLAG_ZONE_KEY))
- return -EBADMSG;
-
- rr->dnskey.zone_key_flag = flags & DNSKEY_FLAG_ZONE_KEY;
- rr->dnskey.sep_flag = flags & DNSKEY_FLAG_SEP;
- return 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;
+ _cleanup_(rewind_dns_packet) DnsPacketRewinder rewinder;
+ size_t offset;
uint16_t rdlength;
- const void *d;
+ bool cache_flush;
int r;
assert(p);
assert(ret);
- saved_rindex = p->rindex;
+ INIT_REWINDER(rewinder, p);
- r = dns_packet_read_key(p, &key, NULL);
+ r = dns_packet_read_key(p, &key, &cache_flush, NULL);
if (r < 0)
- goto fail;
+ return r;
- if (key->class == DNS_CLASS_ANY ||
- key->type == DNS_TYPE_ANY) {
- r = -EBADMSG;
- goto fail;
- }
+ if (!dns_class_is_valid_rr(key->class) || !dns_type_is_valid_rr(key->type))
+ return -EBADMSG;
rr = dns_resource_record_new(key);
- if (!rr) {
- r = -ENOMEM;
- goto fail;
- }
+ if (!rr)
+ return -ENOMEM;
r = dns_packet_read_uint32(p, &rr->ttl, NULL);
if (r < 0)
- goto fail;
+ return r;
+
+ /* RFC 2181, Section 8, suggests to
+ * treat a TTL with the MSB set as a zero TTL. */
+ if (rr->ttl & UINT32_C(0x80000000))
+ rr->ttl = 0;
r = dns_packet_read_uint16(p, &rdlength, NULL);
if (r < 0)
- goto fail;
+ return r;
- if (p->rindex + rdlength > p->size) {
- r = -EBADMSG;
- goto fail;
- }
+ if (p->rindex + rdlength > p->size)
+ return -EBADMSG;
offset = p->rindex;
@@ -1325,13 +1645,13 @@ int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start) {
case DNS_TYPE_SRV:
r = dns_packet_read_uint16(p, &rr->srv.priority, NULL);
if (r < 0)
- goto fail;
+ return r;
r = dns_packet_read_uint16(p, &rr->srv.weight, NULL);
if (r < 0)
- goto fail;
+ return r;
r = dns_packet_read_uint16(p, &rr->srv.port, NULL);
if (r < 0)
- goto fail;
+ return r;
r = dns_packet_read_name(p, &rr->srv.name, true, NULL);
break;
@@ -1345,7 +1665,7 @@ int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start) {
case DNS_TYPE_HINFO:
r = dns_packet_read_string(p, &rr->hinfo.cpu, NULL);
if (r < 0)
- goto fail;
+ return r;
r = dns_packet_read_string(p, &rr->hinfo.os, NULL);
break;
@@ -1353,24 +1673,37 @@ int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start) {
case DNS_TYPE_SPF: /* exactly the same as TXT */
case DNS_TYPE_TXT:
if (rdlength <= 0) {
+ DnsTxtItem *i;
/* RFC 6763, section 6.1 suggests to treat
* empty TXT RRs as equivalent to a TXT record
* with a single empty string. */
- r = strv_extend(&rr->txt.strings, "");
- if (r < 0)
- goto fail;
+ i = malloc0(offsetof(DnsTxtItem, data) + 1); /* for safety reasons we add an extra NUL byte */
+ if (!i)
+ return -ENOMEM;
+
+ rr->txt.items = i;
} else {
+ DnsTxtItem *last = NULL;
+
while (p->rindex < offset + rdlength) {
- char *s;
+ DnsTxtItem *i;
+ const void *data;
+ size_t sz;
- r = dns_packet_read_string(p, &s, NULL);
+ r = dns_packet_read_raw_string(p, &data, &sz, NULL);
if (r < 0)
- goto fail;
+ return r;
- r = strv_consume(&rr->txt.strings, s);
- if (r < 0)
- goto fail;
+ i = malloc0(offsetof(DnsTxtItem, data) + sz + 1); /* extra NUL byte at the end */
+ if (!i)
+ return -ENOMEM;
+
+ memcpy(i->data, data, sz);
+ i->length = sz;
+
+ LIST_INSERT_AFTER(items, rr->txt.items, last, i);
+ last = i;
}
}
@@ -1388,27 +1721,27 @@ int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start) {
case DNS_TYPE_SOA:
r = dns_packet_read_name(p, &rr->soa.mname, true, NULL);
if (r < 0)
- goto fail;
+ return r;
r = dns_packet_read_name(p, &rr->soa.rname, true, NULL);
if (r < 0)
- goto fail;
+ return r;
r = dns_packet_read_uint32(p, &rr->soa.serial, NULL);
if (r < 0)
- goto fail;
+ return r;
r = dns_packet_read_uint32(p, &rr->soa.refresh, NULL);
if (r < 0)
- goto fail;
+ return r;
r = dns_packet_read_uint32(p, &rr->soa.retry, NULL);
if (r < 0)
- goto fail;
+ return r;
r = dns_packet_read_uint32(p, &rr->soa.expire, NULL);
if (r < 0)
- goto fail;
+ return r;
r = dns_packet_read_uint32(p, &rr->soa.minimum, NULL);
break;
@@ -1416,7 +1749,7 @@ int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start) {
case DNS_TYPE_MX:
r = dns_packet_read_uint16(p, &rr->mx.priority, NULL);
if (r < 0)
- goto fail;
+ return r;
r = dns_packet_read_name(p, &rr->mx.exchange, true, NULL);
break;
@@ -1427,49 +1760,43 @@ int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start) {
r = dns_packet_read_uint8(p, &t, &pos);
if (r < 0)
- goto fail;
+ return r;
if (t == 0) {
rr->loc.version = t;
r = dns_packet_read_uint8(p, &rr->loc.size, NULL);
if (r < 0)
- goto fail;
+ return r;
- if (!loc_size_ok(rr->loc.size)) {
- r = -EBADMSG;
- goto fail;
- }
+ if (!loc_size_ok(rr->loc.size))
+ return -EBADMSG;
r = dns_packet_read_uint8(p, &rr->loc.horiz_pre, NULL);
if (r < 0)
- goto fail;
+ return r;
- if (!loc_size_ok(rr->loc.horiz_pre)) {
- r = -EBADMSG;
- goto fail;
- }
+ if (!loc_size_ok(rr->loc.horiz_pre))
+ return -EBADMSG;
r = dns_packet_read_uint8(p, &rr->loc.vert_pre, NULL);
if (r < 0)
- goto fail;
+ return r;
- if (!loc_size_ok(rr->loc.vert_pre)) {
- r = -EBADMSG;
- goto fail;
- }
+ if (!loc_size_ok(rr->loc.vert_pre))
+ return -EBADMSG;
r = dns_packet_read_uint32(p, &rr->loc.latitude, NULL);
if (r < 0)
- goto fail;
+ return r;
r = dns_packet_read_uint32(p, &rr->loc.longitude, NULL);
if (r < 0)
- goto fail;
+ return r;
r = dns_packet_read_uint32(p, &rr->loc.altitude, NULL);
if (r < 0)
- goto fail;
+ return r;
break;
} else {
@@ -1482,260 +1809,429 @@ int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start) {
case DNS_TYPE_DS:
r = dns_packet_read_uint16(p, &rr->ds.key_tag, NULL);
if (r < 0)
- goto fail;
+ return r;
r = dns_packet_read_uint8(p, &rr->ds.algorithm, NULL);
if (r < 0)
- goto fail;
+ return r;
r = dns_packet_read_uint8(p, &rr->ds.digest_type, NULL);
if (r < 0)
- goto fail;
+ return r;
- r = dns_packet_read_public_key(p, rdlength - 4,
- &rr->ds.digest, &rr->ds.digest_size,
- NULL);
+ r = dns_packet_read_memdup(p, rdlength - 4,
+ &rr->ds.digest, &rr->ds.digest_size,
+ NULL);
if (r < 0)
- goto fail;
+ return r;
+
+ if (rr->ds.digest_size <= 0)
+ /* the accepted size depends on the algorithm, but for now
+ just ensure that the value is greater than zero */
+ return -EBADMSG;
break;
+
case DNS_TYPE_SSHFP:
r = dns_packet_read_uint8(p, &rr->sshfp.algorithm, NULL);
if (r < 0)
- goto fail;
+ return r;
r = dns_packet_read_uint8(p, &rr->sshfp.fptype, NULL);
if (r < 0)
- goto fail;
+ return r;
- r = dns_packet_read_public_key(p, rdlength - 2,
- &rr->sshfp.key, &rr->sshfp.key_size,
- NULL);
- break;
+ r = dns_packet_read_memdup(p, rdlength - 2,
+ &rr->sshfp.fingerprint, &rr->sshfp.fingerprint_size,
+ NULL);
- case DNS_TYPE_DNSKEY: {
- uint16_t flags;
- uint8_t proto;
+ if (rr->sshfp.fingerprint_size <= 0)
+ /* the accepted size depends on the algorithm, but for now
+ just ensure that the value is greater than zero */
+ return -EBADMSG;
- r = dns_packet_read_uint16(p, &flags, NULL);
- if (r < 0)
- goto fail;
+ break;
- r = dnskey_parse_flags(rr, flags);
+ case DNS_TYPE_DNSKEY:
+ r = dns_packet_read_uint16(p, &rr->dnskey.flags, NULL);
if (r < 0)
- goto fail;
+ return r;
- r = dns_packet_read_uint8(p, &proto, NULL);
+ r = dns_packet_read_uint8(p, &rr->dnskey.protocol, NULL);
if (r < 0)
- goto fail;
-
- /* protocol is required to be always 3 */
- if (proto != 3) {
- r = -EBADMSG;
- goto fail;
- }
+ return r;
r = dns_packet_read_uint8(p, &rr->dnskey.algorithm, NULL);
if (r < 0)
- goto fail;
+ return r;
+
+ r = dns_packet_read_memdup(p, rdlength - 4,
+ &rr->dnskey.key, &rr->dnskey.key_size,
+ NULL);
+
+ if (rr->dnskey.key_size <= 0)
+ /* the accepted size depends on the algorithm, but for now
+ just ensure that the value is greater than zero */
+ return -EBADMSG;
- r = dns_packet_read_public_key(p, rdlength - 4,
- &rr->dnskey.key, &rr->dnskey.key_size,
- NULL);
break;
- }
case DNS_TYPE_RRSIG:
r = dns_packet_read_uint16(p, &rr->rrsig.type_covered, NULL);
if (r < 0)
- goto fail;
+ return r;
r = dns_packet_read_uint8(p, &rr->rrsig.algorithm, NULL);
if (r < 0)
- goto fail;
+ return r;
r = dns_packet_read_uint8(p, &rr->rrsig.labels, NULL);
if (r < 0)
- goto fail;
+ return r;
r = dns_packet_read_uint32(p, &rr->rrsig.original_ttl, NULL);
if (r < 0)
- goto fail;
+ return r;
r = dns_packet_read_uint32(p, &rr->rrsig.expiration, NULL);
if (r < 0)
- goto fail;
+ return r;
r = dns_packet_read_uint32(p, &rr->rrsig.inception, NULL);
if (r < 0)
- goto fail;
+ return r;
r = dns_packet_read_uint16(p, &rr->rrsig.key_tag, NULL);
if (r < 0)
- goto fail;
+ return r;
r = dns_packet_read_name(p, &rr->rrsig.signer, false, NULL);
if (r < 0)
- goto fail;
+ return r;
+
+ r = dns_packet_read_memdup(p, offset + rdlength - p->rindex,
+ &rr->rrsig.signature, &rr->rrsig.signature_size,
+ NULL);
+
+ if (rr->rrsig.signature_size <= 0)
+ /* the accepted size depends on the algorithm, but for now
+ just ensure that the value is greater than zero */
+ return -EBADMSG;
- r = dns_packet_read_public_key(p, offset + rdlength - p->rindex,
- &rr->rrsig.signature, &rr->rrsig.signature_size,
- NULL);
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;
+ return r;
- while (p->rindex != offset + rdlength) {
- r = dns_packet_read_type_window(p, &rr->nsec.types, NULL);
- if (r < 0)
- goto fail;
- }
+ r = dns_packet_read_type_windows(p, &rr->nsec.types, offset + rdlength - p->rindex, NULL);
- break;
+ /* We accept empty NSEC bitmaps. The bit indicating the presence of the NSEC record itself
+ * is redundant and in e.g., RFC4956 this fact is used to define a use for NSEC records
+ * without the NSEC bit set. */
+ break;
+ }
case DNS_TYPE_NSEC3: {
uint8_t size;
r = dns_packet_read_uint8(p, &rr->nsec3.algorithm, NULL);
if (r < 0)
- goto fail;
+ return r;
r = dns_packet_read_uint8(p, &rr->nsec3.flags, NULL);
if (r < 0)
- goto fail;
+ return r;
r = dns_packet_read_uint16(p, &rr->nsec3.iterations, NULL);
if (r < 0)
- goto fail;
+ return r;
+ /* this may be zero */
r = dns_packet_read_uint8(p, &size, NULL);
if (r < 0)
- goto fail;
+ return r;
- rr->nsec3.salt_size = size;
+ r = dns_packet_read_memdup(p, size, &rr->nsec3.salt, &rr->nsec3.salt_size, NULL);
+ if (r < 0)
+ return r;
- r = dns_packet_read_blob(p, &d, rr->nsec3.salt_size, NULL);
+ r = dns_packet_read_uint8(p, &size, NULL);
if (r < 0)
- goto fail;
+ return r;
- rr->nsec3.salt = memdup(d, rr->nsec3.salt_size);
- if (!rr->nsec3.salt) {
- r = -ENOMEM;
- goto fail;
- }
+ if (size <= 0)
+ return -EBADMSG;
- r = dns_packet_read_uint8(p, &size, NULL);
+ r = dns_packet_read_memdup(p, size,
+ &rr->nsec3.next_hashed_name, &rr->nsec3.next_hashed_name_size,
+ NULL);
if (r < 0)
- goto fail;
+ return r;
- rr->nsec3.next_hashed_name_size = size;
+ r = dns_packet_read_type_windows(p, &rr->nsec3.types, offset + rdlength - p->rindex, NULL);
+
+ /* empty non-terminals can have NSEC3 records, so empty bitmaps are allowed */
+
+ break;
+ }
- r = dns_packet_read(p, rr->nsec3.next_hashed_name_size, &d, NULL);
+ case DNS_TYPE_TLSA:
+ r = dns_packet_read_uint8(p, &rr->tlsa.cert_usage, NULL);
if (r < 0)
- goto fail;
+ return r;
- rr->nsec3.next_hashed_name = memdup(d, rr->nsec3.next_hashed_name_size);
- if (!rr->nsec3.next_hashed_name) {
- r = -ENOMEM;
- goto fail;
- }
+ r = dns_packet_read_uint8(p, &rr->tlsa.selector, NULL);
+ if (r < 0)
+ return r;
- r = dns_packet_append_types(p, rr->nsec3.types, NULL);
+ r = dns_packet_read_uint8(p, &rr->tlsa.matching_type, NULL);
if (r < 0)
- goto fail;
+ return r;
+
+ r = dns_packet_read_memdup(p, rdlength - 3,
+ &rr->tlsa.data, &rr->tlsa.data_size,
+ NULL);
+
+ if (rr->tlsa.data_size <= 0)
+ /* the accepted size depends on the algorithm, but for now
+ just ensure that the value is greater than zero */
+ return -EBADMSG;
break;
- }
- default:
- unparseable:
- r = dns_packet_read(p, rdlength, &d, NULL);
+
+ case DNS_TYPE_CAA:
+ r = dns_packet_read_uint8(p, &rr->caa.flags, NULL);
if (r < 0)
- goto fail;
+ return r;
- rr->generic.data = memdup(d, rdlength);
- if (!rr->generic.data) {
- r = -ENOMEM;
- goto fail;
- }
+ r = dns_packet_read_string(p, &rr->caa.tag, NULL);
+ if (r < 0)
+ return r;
+
+ r = dns_packet_read_memdup(p,
+ rdlength + offset - p->rindex,
+ &rr->caa.value, &rr->caa.value_size, NULL);
+
+ break;
+
+ case DNS_TYPE_OPT: /* we only care about the header of OPT for now. */
+ case DNS_TYPE_OPENPGPKEY:
+ default:
+ unparseable:
+ r = dns_packet_read_memdup(p, rdlength, &rr->generic.data, &rr->generic.data_size, NULL);
- rr->generic.size = rdlength;
break;
}
if (r < 0)
- goto fail;
- if (p->rindex != offset + rdlength) {
- r = -EBADMSG;
- goto fail;
- }
+ return r;
+ if (p->rindex != offset + rdlength)
+ return -EBADMSG;
*ret = rr;
rr = NULL;
+ if (ret_cache_flush)
+ *ret_cache_flush = cache_flush;
if (start)
- *start = saved_rindex;
+ *start = rewinder.saved_rindex;
+ CANCEL_REWINDER(rewinder);
return 0;
-fail:
- dns_packet_rewind(p, saved_rindex);
- return r;
+}
+
+static bool opt_is_good(DnsResourceRecord *rr, bool *rfc6975) {
+ const uint8_t* p;
+ bool found_dau_dhu_n3u = false;
+ size_t l;
+
+ /* Checks whether the specified OPT RR is well-formed and whether it contains RFC6975 data (which is not OK in
+ * a reply). */
+
+ assert(rr);
+ assert(rr->key->type == DNS_TYPE_OPT);
+
+ /* Check that the version is 0 */
+ if (((rr->ttl >> 16) & UINT32_C(0xFF)) != 0) {
+ *rfc6975 = false;
+ return true; /* if it's not version 0, it's OK, but we will ignore the OPT field contents */
+ }
+
+ p = rr->opt.data;
+ l = rr->opt.data_size;
+ while (l > 0) {
+ uint16_t option_code, option_length;
+
+ /* At least four bytes for OPTION-CODE and OPTION-LENGTH are required */
+ if (l < 4U)
+ return false;
+
+ option_code = unaligned_read_be16(p);
+ option_length = unaligned_read_be16(p + 2);
+
+ if (l < option_length + 4U)
+ return false;
+
+ /* RFC 6975 DAU, DHU or N3U fields found. */
+ if (IN_SET(option_code, 5, 6, 7))
+ found_dau_dhu_n3u = true;
+
+ p += option_length + 4U;
+ l -= option_length + 4U;
+ }
+
+ *rfc6975 = found_dau_dhu_n3u;
+ return true;
}
int dns_packet_extract(DnsPacket *p) {
_cleanup_(dns_question_unrefp) DnsQuestion *question = NULL;
_cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
- size_t saved_rindex;
+ _cleanup_(rewind_dns_packet) DnsPacketRewinder rewinder = {};
unsigned n, i;
int r;
if (p->extracted)
return 0;
- saved_rindex = p->rindex;
+ INIT_REWINDER(rewinder, p);
dns_packet_rewind(p, DNS_PACKET_HEADER_SIZE);
n = DNS_PACKET_QDCOUNT(p);
if (n > 0) {
question = dns_question_new(n);
- if (!question) {
- r = -ENOMEM;
- goto finish;
- }
+ if (!question)
+ return -ENOMEM;
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;
+ return r;
+
+ if (cache_flush)
+ return -EBADMSG;
+
+ if (!dns_type_is_valid_query(key->type))
+ return -EBADMSG;
r = dns_question_add(question, key);
if (r < 0)
- goto finish;
+ return r;
}
}
n = DNS_PACKET_RRCOUNT(p);
if (n > 0) {
+ _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *previous = NULL;
+ bool bad_opt = false;
+
answer = dns_answer_new(n);
- if (!answer) {
- r = -ENOMEM;
- goto finish;
- }
+ if (!answer)
+ return -ENOMEM;
for (i = 0; i < n; i++) {
_cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
+ bool cache_flush = false;
- r = dns_packet_read_rr(p, &rr, NULL);
+ r = dns_packet_read_rr(p, &rr, &cache_flush, NULL);
if (r < 0)
- goto finish;
+ return r;
+
+ /* Try to reduce memory usage a bit */
+ if (previous)
+ dns_resource_key_reduce(&rr->key, &previous->key);
+
+ if (rr->key->type == DNS_TYPE_OPT) {
+ bool has_rfc6975;
+
+ if (p->opt || bad_opt) {
+ /* Multiple OPT RRs? if so, let's ignore all, because there's something wrong
+ * with the server, and if one is valid we wouldn't know which one. */
+ log_debug("Multiple OPT RRs detected, ignoring all.");
+ bad_opt = true;
+ continue;
+ }
+
+ if (!dns_name_is_root(dns_resource_key_name(rr->key))) {
+ /* If the OPT RR is not owned by the root domain, then it is bad, let's ignore
+ * it. */
+ log_debug("OPT RR is not owned by root domain, ignoring.");
+ bad_opt = true;
+ continue;
+ }
+
+ if (i < DNS_PACKET_ANCOUNT(p) + DNS_PACKET_NSCOUNT(p)) {
+ /* OPT RR is in the wrong section? Some Belkin routers do this. This is a hint
+ * the EDNS implementation is borked, like the Belkin one is, hence ignore
+ * it. */
+ log_debug("OPT RR in wrong section, ignoring.");
+ bad_opt = true;
+ continue;
+ }
+
+ if (!opt_is_good(rr, &has_rfc6975)) {
+ log_debug("Malformed OPT RR, ignoring.");
+ bad_opt = true;
+ continue;
+ }
+
+ if (DNS_PACKET_QR(p)) {
+ /* Additional checks for responses */
+
+ if (!DNS_RESOURCE_RECORD_OPT_VERSION_SUPPORTED(rr)) {
+ /* If this is a reply and we don't know the EDNS version then something
+ * is weird... */
+ log_debug("EDNS version newer that our request, bad server.");
+ return -EBADMSG;
+ }
+
+ if (has_rfc6975) {
+ /* If the OPT RR contains RFC6975 algorithm data, then this is indication that
+ * the server just copied the OPT it got from us (which contained that data)
+ * back into the reply. If so, then it doesn't properly support EDNS, as
+ * RFC6975 makes it very clear that the algorithm data should only be contained
+ * in questions, never in replies. Crappy Belkin routers copy the OPT data for
+ * example, hence let's detect this so that we downgrade early. */
+ log_debug("OPT RR contained RFC6975 data, ignoring.");
+ bad_opt = true;
+ continue;
+ }
+ }
+
+ 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)
+ return r;
+ }
- r = dns_answer_add(answer, rr);
- if (r < 0)
- goto finish;
+ /* Remember this RR, so that we potentically can merge it's ->key object with the next RR. Note
+ * that we only do this if we actually decided to keep the RR around. */
+ dns_resource_record_unref(previous);
+ previous = dns_resource_record_ref(rr);
}
+
+ if (bad_opt)
+ p->opt = dns_resource_record_unref(p->opt);
}
p->question = question;
@@ -1746,11 +2242,32 @@ int dns_packet_extract(DnsPacket *p) {
p->extracted = true;
- r = 0;
+ /* no CANCEL, always rewind */
+ return 0;
+}
-finish:
- p->rindex = saved_rindex;
- 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] = {
@@ -1772,6 +2289,7 @@ static const char* const dns_rcode_table[_DNS_RCODE_MAX_DEFINED] = {
[DNS_RCODE_BADNAME] = "BADNAME",
[DNS_RCODE_BADALG] = "BADALG",
[DNS_RCODE_BADTRUNC] = "BADTRUNC",
+ [DNS_RCODE_BADCOOKIE] = "BADCOOKIE",
};
DEFINE_STRING_TABLE_LOOKUP(dns_rcode, int);
@@ -1781,17 +2299,3 @@ static const char* const dns_protocol_table[_DNS_PROTOCOL_MAX] = {
[DNS_PROTOCOL_LLMNR] = "llmnr",
};
DEFINE_STRING_TABLE_LOOKUP(dns_protocol, DnsProtocol);
-
-static const char* const dnssec_algorithm_table[_DNSSEC_ALGORITHM_MAX_DEFINED] = {
- [DNSSEC_ALGORITHM_RSAMD5] = "RSAMD5",
- [DNSSEC_ALGORITHM_DH] = "DH",
- [DNSSEC_ALGORITHM_DSA] = "DSA",
- [DNSSEC_ALGORITHM_ECC] = "ECC",
- [DNSSEC_ALGORITHM_RSASHA1] = "RSASHA1",
- [DNSSEC_ALGORITHM_DSA_NSEC3_SHA1] = "DSA-NSEC3-SHA1",
- [DNSSEC_ALGORITHM_RSASHA1_NSEC3_SHA1] = "RSASHA1-NSEC3-SHA1",
- [DNSSEC_ALGORITHM_INDIRECT] = "INDIRECT",
- [DNSSEC_ALGORITHM_PRIVATEDNS] = "PRIVATEDNS",
- [DNSSEC_ALGORITHM_PRIVATEOID] = "PRIVATEOID",
-};
-DEFINE_STRING_TABLE_LOOKUP(dnssec_algorithm, int);
generated by cgit v1.2.3-54-g00ecf (git 2.45.2) at 2024-08-14 23:39:32 +0000