-/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
-
/***
This file is part of systemd.
#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;
size_t a;
((uint8_t*) d)[0] = (uint8_t) size;
- if (size > 0)
- memcpy(((uint8_t*) d) + 1, s, size);
+ memcpy_safe(((uint8_t*) d) + 1, s, size);
return 0;
}
/* 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];
- }
+ 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
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));
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, canonical_candidate, &n);
if (r < 0)
goto fail;
saved_size = p->size;
- r = dns_packet_append_name(p, DNS_RESOURCE_KEY_NAME(k), true, true, NULL);
+ r = dns_packet_append_name(p, dns_resource_key_name(k), true, true, NULL);
if (r < 0)
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)
/* 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;
}
}
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) {
- size_t saved_rindex;
+ _cleanup_(rewind_dns_packet) DnsPacketRewinder rewinder;
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, ret, NULL);
if (r < 0)
- goto fail;
+ return r;
if (size)
*size = c;
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_name(
bool allow_compression,
size_t *start) {
- size_t saved_rindex, after_rindex = 0, jump_barrier;
+ _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;
assert(p);
assert(_ret);
+ INIT_REWINDER(rewinder, p);
+ jump_barrier = p->rindex;
if (p->refuse_compression)
allow_compression = false;
- saved_rindex = p->rindex;
- jump_barrier = p->rindex;
-
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 */
/* Literal label */
r = dns_packet_read(p, c, (const void**) &label, NULL);
if (r < 0)
- goto fail;
+ return r;
- if (!GREEDY_REALLOC(ret, allocated, n + !first + DNS_LABEL_ESCAPED_MAX)) {
- r = -ENOMEM;
- goto fail;
- }
+ if (!GREEDY_REALLOC(ret, allocated, n + !first + DNS_LABEL_ESCAPED_MAX))
+ return -ENOMEM;
if (first)
first = false;
r = dns_label_escape(label, c, ret + n, DNS_LABEL_ESCAPED_MAX);
if (r < 0)
- goto fail;
+ return r;
n += r;
continue;
/* 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;
/* 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;
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 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;
r = bitmap_set(*types, n);
if (r < 0)
- goto fail;
+ return r;
}
- bit ++;
+ bit++;
bitmask >>= 1;
}
}
return -EBADMSG;
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_windows(DnsPacket *p, Bitmap **types, size_t size, size_t *start) {
- size_t saved_rindex;
+ _cleanup_(rewind_dns_packet) DnsPacketRewinder rewinder;
int r;
- saved_rindex = p->rindex;
+ INIT_REWINDER(rewinder, p);
- while (p->rindex < saved_rindex + size) {
+ while (p->rindex < rewinder.saved_rindex + size) {
r = dns_packet_read_type_window(p, types, NULL);
if (r < 0)
- goto fail;
+ return r;
/* don't read past end of current RR */
- if (p->rindex > saved_rindex + size) {
- r = -EBADMSG;
- goto fail;
- }
+ if (p->rindex > rewinder.saved_rindex + size)
+ return -EBADMSG;
}
- if (p->rindex != saved_rindex + size) {
- r = -EBADMSG;
- goto fail;
- }
+ if (p->rindex != rewinder.saved_rindex + size)
+ return -EBADMSG;
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_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;
if (p->protocol == DNS_PROTOCOL_MDNS) {
/* See RFC6762, Section 10.2 */
}
key = dns_resource_key_new_consume(class, type, name);
- if (!key) {
- r = -ENOMEM;
- goto fail;
- }
+ if (!key)
+ return -ENOMEM;
name = NULL;
*ret = key;
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 loc_size_ok(uint8_t size) {
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;
bool cache_flush;
int r;
assert(p);
assert(ret);
- saved_rindex = p->rindex;
+ INIT_REWINDER(rewinder, p);
r = dns_packet_read_key(p, &key, &cache_flush, NULL);
if (r < 0)
- goto fail;
+ return r;
- if (!dns_class_is_valid_rr(key->class)||
- !dns_type_is_valid_rr(key->type)) {
- 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. */
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;
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;
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;
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;
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;
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 {
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_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) {
+ 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 */
- r = -EBADMSG;
- goto fail;
- }
+ 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_memdup(p, rdlength - 2,
&rr->sshfp.fingerprint, &rr->sshfp.fingerprint_size,
NULL);
- if (rr->sshfp.fingerprint_size <= 0) {
+ 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 */
- r = -EBADMSG;
- goto fail;
- }
+ return -EBADMSG;
break;
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, &rr->dnskey.protocol, NULL);
if (r < 0)
- 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) {
+ 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 */
- r = -EBADMSG;
- goto fail;
- }
+ return -EBADMSG;
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) {
+ 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 */
- r = -EBADMSG;
- goto fail;
- }
+ return -EBADMSG;
break;
r = dns_packet_read_name(p, &rr->nsec.next_domain_name, allow_compressed, NULL);
if (r < 0)
- goto fail;
+ return r;
r = dns_packet_read_type_windows(p, &rr->nsec.types, offset + rdlength - p->rindex, NULL);
- if (r < 0)
- 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
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;
r = dns_packet_read_memdup(p, size, &rr->nsec3.salt, &rr->nsec3.salt_size, NULL);
if (r < 0)
- goto fail;
+ return r;
r = dns_packet_read_uint8(p, &size, NULL);
if (r < 0)
- goto fail;
+ return r;
- if (size <= 0) {
- r = -EBADMSG;
- goto fail;
- }
+ if (size <= 0)
+ return -EBADMSG;
- r = dns_packet_read_memdup(p, size, &rr->nsec3.next_hashed_name, &rr->nsec3.next_hashed_name_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;
r = dns_packet_read_type_windows(p, &rr->nsec3.types, offset + rdlength - p->rindex, NULL);
- if (r < 0)
- goto fail;
/* empty non-terminals can have NSEC3 records, so empty bitmaps are allowed */
break;
}
+ case DNS_TYPE_TLSA:
+ r = dns_packet_read_uint8(p, &rr->tlsa.cert_usage, NULL);
+ if (r < 0)
+ return r;
+
+ r = dns_packet_read_uint8(p, &rr->tlsa.selector, NULL);
+ if (r < 0)
+ return r;
+
+ r = dns_packet_read_uint8(p, &rr->tlsa.matching_type, NULL);
+ if (r < 0)
+ 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;
+
+ case DNS_TYPE_CAA:
+ r = dns_packet_read_uint8(p, &rr->caa.flags, NULL);
+ if (r < 0)
+ return r;
+
+ 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.size, NULL);
- if (r < 0)
- goto fail;
+ r = dns_packet_read_memdup(p, rdlength, &rr->generic.data, &rr->generic.data_size, NULL);
+
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)
+ return false;
+
+ 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;
r = dns_packet_read_key(p, &key, &cache_flush, NULL);
if (r < 0)
- goto finish;
+ return r;
- if (cache_flush) {
- r = -EBADMSG;
- goto finish;
- }
+ if (cache_flush)
+ return -EBADMSG;
- if (!dns_type_is_valid_query(key->type)) {
- r = -EBADMSG;
- goto finish;
- }
+ 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;
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))) {
- r = -EBADMSG;
- goto finish;
+ 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;
}
- /* The OPT RR is only valid in the Additional section */
if (i < DNS_PACKET_ANCOUNT(p) + DNS_PACKET_NSCOUNT(p)) {
- r = -EBADMSG;
- goto finish;
+ /* 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;
}
- /* Two OPT RRs? */
- if (p->opt) {
- r = -EBADMSG;
- goto finish;
+ 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. */
+ /* 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;
+ return r;
}
+
+ /* 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;
p->extracted = true;
- r = 0;
-
-finish:
- p->rindex = saved_rindex;
- return r;
+ /* no CANCEL, always rewind */
+ return 0;
}
int dns_packet_is_reply_for(DnsPacket *p, const DnsResourceKey *key) {
projects / thirdparty / systemd.git / blobdiff