#include "memory-util.h"
#include "resolved-dns-packet.h"
#include "set.h"
+#include "stdio-util.h"
#include "string-table.h"
#include "strv.h"
#include "unaligned.h"
#include "utf8.h"
-#include "util.h"
#define EDNS0_OPT_DO (1<<15)
if (DNS_PACKET_OPCODE(p) != 0)
return -EBADMSG;
- if (DNS_PACKET_TC(p))
- return -EBADMSG;
-
switch (p->protocol) {
case DNS_PROTOCOL_LLMNR:
case DNS_PROTOCOL_DNS:
+ if (DNS_PACKET_TC(p)) /* mDNS query may have truncation flag. */
+ return -EBADMSG;
+
/* RFC 4795, Section 2.1.1. says to discard all queries with QDCOUNT != 1 */
if (DNS_PACKET_QDCOUNT(p) != 1)
return -EBADMSG;
while (!dns_name_is_root(name)) {
const char *z = name;
- char label[DNS_LABEL_MAX];
+ char label[DNS_LABEL_MAX+1];
size_t n = 0;
if (allow_compression)
if (r < 0)
goto fail;
- /* RFC 2782 states "Unless and until permitted by future standards
- * action, name compression is not to be used for this field." */
- r = dns_packet_append_name(p, rr->srv.name, false, true, NULL);
+ /* RFC 2782 states "Unless and until permitted by future standards action, name compression
+ * is not to be used for this field." Hence we turn off compression here. */
+ r = dns_packet_append_name(p, rr->srv.name, /* allow_compression= */ false, /* canonical_candidate= */ true, NULL);
break;
case DNS_TYPE_PTR:
int dns_packet_read(DnsPacket *p, size_t sz, const void **ret, size_t *start) {
assert(p);
+ assert(p->rindex <= p->size);
- if (p->rindex + sz > p->size)
+ if (sz > p->size - p->rindex)
return -EMSGSIZE;
if (ret)
}
int dns_packet_read_string(DnsPacket *p, char **ret, size_t *start) {
- assert(p);
-
_cleanup_(rewind_dns_packet) DnsPacketRewinder rewinder = REWINDER_INIT(p);
+ _cleanup_free_ char *t = NULL;
const void *d;
- char *t;
uint8_t c;
int r;
+ assert(p);
+
r = dns_packet_read_uint8(p, &c, NULL);
if (r < 0)
return r;
if (r < 0)
return r;
- if (memchr(d, 0, c))
- return -EBADMSG;
-
- t = strndup(d, c);
- if (!t)
- return -ENOMEM;
+ r = make_cstring(d, c, MAKE_CSTRING_REFUSE_TRAILING_NUL, &t);
+ if (r < 0)
+ return r;
- if (!utf8_is_valid(t)) {
- free(t);
+ if (!utf8_is_valid(t))
return -EBADMSG;
- }
- *ret = t;
+ *ret = TAKE_PTR(t);
if (start)
*start = rewinder.saved_rindex;
_cleanup_(rewind_dns_packet) DnsPacketRewinder rewinder = REWINDER_INIT(p);
int r;
- while (p->rindex < rewinder.saved_rindex + size) {
+ while (p->rindex - rewinder.saved_rindex < size) {
r = dns_packet_read_type_window(p, types, NULL);
if (r < 0)
return r;
+ assert(p->rindex >= rewinder.saved_rindex);
+
/* don't read past end of current RR */
- if (p->rindex > rewinder.saved_rindex + size)
+ if (p->rindex - rewinder.saved_rindex > size)
return -EBADMSG;
}
- if (p->rindex != rewinder.saved_rindex + size)
+ if (p->rindex - rewinder.saved_rindex != size)
return -EBADMSG;
if (start)
if (r < 0)
return r;
- if (p->rindex + rdlength > p->size)
+ if (rdlength > p->size - p->rindex)
return -EBADMSG;
offset = p->rindex;
r = dns_packet_read_uint16(p, &rr->srv.port, NULL);
if (r < 0)
return r;
- r = dns_packet_read_name(p, &rr->srv.name, true, NULL);
+
+ /* RFC 2782 states "Unless and until permitted by future standards action, name compression
+ * is not to be used for this field." Nonetheless, we support it here, in the interest of
+ * increasing compatibility with implementations that do not implement this correctly. After
+ * all we didn't do this right once upon a time ourselves (see
+ * https://github.com/systemd/systemd/issues/9793). */
+ r = dns_packet_read_name(p, &rr->srv.name, /* allow_compression= */ true, NULL);
break;
case DNS_TYPE_PTR:
} else {
DnsTxtItem *last = NULL;
- while (p->rindex < offset + rdlength) {
+ while (p->rindex - offset < rdlength) {
DnsTxtItem *i;
const void *data;
size_t sz;
if (r < 0)
return r;
- if (rdlength + offset < p->rindex)
+ if (rdlength < p->rindex - offset)
return -EBADMSG;
r = dns_packet_read_memdup(p, offset + rdlength - p->rindex,
if (r < 0)
return r;
+ if (rdlength < p->rindex - offset)
+ return -EBADMSG;
+
r = dns_packet_read_type_windows(p, &rr->nsec.types, offset + rdlength - p->rindex, NULL);
/* We accept empty NSEC bitmaps. The bit indicating the presence of the NSEC record itself
if (r < 0)
return r;
+ if (rdlength < p->rindex - offset)
+ return -EBADMSG;
+
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 */
if (r < 0)
return r;
- if (rdlength + offset < p->rindex)
+ if (rdlength < p->rindex - offset)
return -EBADMSG;
r = dns_packet_read_memdup(p,
}
if (r < 0)
return r;
- if (p->rindex != offset + rdlength)
+ if (p->rindex - offset != rdlength)
return -EBADMSG;
if (ret)
} else {
DnsAnswerFlags flags = 0;
- if (p->protocol == DNS_PROTOCOL_MDNS && !cache_flush)
- flags |= DNS_ANSWER_SHARED_OWNER;
+ if (p->protocol == DNS_PROTOCOL_MDNS) {
+ flags |= DNS_ANSWER_REFUSE_TTL_NO_MATCH;
+ if (!cache_flush)
+ flags |= DNS_ANSWER_SHARED_OWNER;
+ }
/* 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. */
+ * the Additional or Authority sections.
+ * This restriction does not apply to mDNS records (RFC 6762). */
if (i < DNS_PACKET_ANCOUNT(p))
flags |= DNS_ANSWER_CACHEABLE|DNS_ANSWER_SECTION_ANSWER;
else if (i < DNS_PACKET_ANCOUNT(p) + DNS_PACKET_NSCOUNT(p))
flags |= DNS_ANSWER_SECTION_AUTHORITY;
- else
+ else {
flags |= DNS_ANSWER_SECTION_ADDITIONAL;
+ if (p->protocol == DNS_PROTOCOL_MDNS)
+ flags |= DNS_ANSWER_CACHEABLE;
+ }
r = dns_answer_add(answer, rr, p->ifindex, flags, NULL);
if (r < 0)
/* Remember this RR, so that we can potentially merge its ->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);
+ DNS_RR_REPLACE(previous, dns_resource_record_ref(rr));
}
if (bad_opt) {
};
DEFINE_STRING_TABLE_LOOKUP(dns_rcode, int);
+const char *format_dns_rcode(int i, char buf[static DECIMAL_STR_MAX(int)]) {
+ const char *p = dns_rcode_to_string(i);
+ if (p)
+ return p;
+
+ return snprintf_ok(buf, DECIMAL_STR_MAX(int), "%i", i);
+}
+
static const char* const dns_protocol_table[_DNS_PROTOCOL_MAX] = {
[DNS_PROTOCOL_DNS] = "dns",
[DNS_PROTOCOL_MDNS] = "mdns",
projects / thirdparty / systemd.git / blobdiff