along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
+#include "alloc-util.h"
#include "dns-domain.h"
#include "resolved-dns-packet.h"
#include "string-table.h"
#include "utf8.h"
#include "util.h"
+#define EDNS0_OPT_DO (1<<15)
+
int dns_packet_new(DnsPacket **ret, DnsProtocol protocol, size_t mtu) {
DnsPacket *p;
size_t a;
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 */,
- 0 /* tc */,
+ 0/* tc */,
0 /* t */,
0 /* ra */,
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 */,
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;
if (!p)
return NULL;
+ assert(!p->on_stack);
+
assert(p->n_ref > 0);
p->n_ref++;
return 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) {
assert(p->n_ref > 0);
+ dns_packet_unref(p->more);
+
if (p->n_ref == 1)
dns_packet_free(p);
else
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)
break;
+ case DNS_PROTOCOL_MDNS:
+ /* RFC 6762, Section 18 */
+ if (DNS_PACKET_RCODE(p) != 0)
+ return -EBADMSG;
+
+ break;
+
default:
break;
}
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)
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;
}
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;
}
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;
+
+ if (size > 0)
+ memcpy(((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;
+ uint8_t *w;
int r;
assert(p);
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) {
+ 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++) {
+ if (d[i] >= 'A' && d[i] <= 'Z')
+ w[i] = (uint8_t) (d[i] - 'A' + 'a');
+ else
+ w[i] = (uint8_t) 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;
}
return r;
}
-int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *start) {
- size_t saved_size, rdlength_offset, end, rdlength;
+/* Append the OPT pseudo-RR described in RFC6891 */
+int dns_packet_append_opt_rr(DnsPacket *p, uint16_t max_udp_size, bool edns0_do, 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);
+
+ 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;
+
+ /* 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, 0, 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 */
+ r = dns_packet_append_uint16(p, 0, NULL);
+ if (r < 0)
+ goto fail;
+
+ 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 *rdata_start) {
+ size_t saved_size, rdlength_offset, end, rdlength, rds;
int r;
assert(p);
if (r < 0)
goto fail;
+ rds = p->size - saved_size;
+
switch (rr->unparseable ? _DNS_TYPE_INVALID : rr->key->type) {
case DNS_TYPE_SRV:
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;
}
r = 0;
break;
- }
case DNS_TYPE_A:
r = dns_packet_append_blob(p, &rr->a.in_addr, sizeof(struct in_addr), 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;
goto fail;
break;
+
case DNS_TYPE_NSEC3:
r = dns_packet_append_uint8(p, rr->nsec3.algorithm, NULL);
if (r < 0)
goto fail;
break;
+
+ case DNS_TYPE_OPT:
case _DNS_TYPE_INVALID: /* unparseable */
default:
if (start)
*start = saved_size;
+ if (rdata_start)
+ *rdata_start = rds;
+
return 0;
fail:
return r;
}
+int dns_packet_read_raw_string(DnsPacket *p, const void **ret, size_t *size, size_t *start) {
+ size_t saved_rindex;
+ uint8_t c;
+ int r;
+
+ assert(p);
+
+ saved_rindex = p->rindex;
+
+ r = dns_packet_read_uint8(p, &c, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_read(p, c, ret, NULL);
+ if (r < 0)
+ goto fail;
+
+ if (size)
+ *size = c;
+ if (start)
+ *start = saved_rindex;
+
+ return 0;
+
+fail:
+ dns_packet_rewind(p, saved_rindex);
+ return r;
+}
+
int dns_packet_read_name(
DnsPacket *p,
char **_ret,
/* End of name */
break;
else if (c <= 63) {
- _cleanup_free_ char *t = NULL;
const char *label;
/* Literal label */
if (r < 0)
goto fail;
- r = dns_label_escape(label, c, &t);
- if (r < 0)
- goto fail;
-
- if (!GREEDY_REALLOC(ret, allocated, n + !first + strlen(t) + 1)) {
+ if (!GREEDY_REALLOC(ret, allocated, n + !first + DNS_LABEL_ESCAPED_MAX)) {
r = -ENOMEM;
goto fail;
}
- 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)
+ goto fail;
- memcpy(ret + n, t, r);
n += r;
continue;
} else if (allow_compression && (c & 0xc0) == 0xc0) {
int dns_packet_read_key(DnsPacket *p, DnsResourceKey **ret, size_t *start) {
_cleanup_free_ char *name = NULL;
+ bool cache_flush = true;
uint16_t class, type;
DnsResourceKey *key;
size_t saved_rindex;
if (r < 0)
goto fail;
+ if (p->protocol == DNS_PROTOCOL_MDNS) {
+ /* See RFC6762, Section 10.2 */
+
+ if (class & MDNS_RR_CACHE_FLUSH)
+ class &= ~MDNS_RR_CACHE_FLUSH;
+ else
+ cache_flush = false;
+ }
+
key = dns_resource_key_new_consume(class, type, name);
if (!key) {
r = -ENOMEM;
goto fail;
}
+ key->cache_flush = cache_flush;
+
name = NULL;
*ret = key;
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) {
_cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
_cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
goto fail;
if (key->class == DNS_CLASS_ANY ||
- key->type == DNS_TYPE_ANY) {
+ key->type == DNS_TYPE_ANY ||
+ key->type == DNS_TYPE_AXFR ||
+ key->type == DNS_TYPE_IXFR) {
r = -EBADMSG;
goto fail;
}
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;
}
}
}
break;
+
case DNS_TYPE_SSHFP:
r = dns_packet_read_uint8(p, &rr->sshfp.algorithm, NULL);
if (r < 0)
break;
- case DNS_TYPE_DNSKEY: {
- uint16_t flags;
- uint8_t proto;
-
- r = dns_packet_read_uint16(p, &flags, NULL);
- if (r < 0)
- goto fail;
-
- 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;
- 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;
- }
-
r = dns_packet_read_uint8(p, &rr->dnskey.algorithm, NULL);
if (r < 0)
goto fail;
}
break;
- }
case DNS_TYPE_RRSIG:
r = dns_packet_read_uint16(p, &rr->rrsig.type_covered, 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 explicly 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;
if (r < 0)
goto fail;
- /* The types bitmap must contain at least the NSEC record itself, so an empty bitmap means
- something went wrong */
- if (bitmap_isclear(rr->nsec.types)) {
- r = -EBADMSG;
- goto fail;
- }
+ /* 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;
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);
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) {
+
+ /* 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 {
+ r = dns_answer_add(answer, rr, p->ifindex);
+ if (r < 0)
+ goto 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",
[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);
projects / thirdparty / systemd.git / blobdiff