summaryrefslogtreecommitdiff
path: root/src/grp-resolve/systemd-resolved/resolved-dns-packet.c
diff options
context:
space:
mode:
Diffstat (limited to 'src/grp-resolve/systemd-resolved/resolved-dns-packet.c')
-rw-r--r--src/grp-resolve/systemd-resolved/resolved-dns-packet.c2255
1 files changed, 2255 insertions, 0 deletions
diff --git a/src/grp-resolve/systemd-resolved/resolved-dns-packet.c b/src/grp-resolve/systemd-resolved/resolved-dns-packet.c
new file mode 100644
index 0000000000..b7907bb511
--- /dev/null
+++ b/src/grp-resolve/systemd-resolved/resolved-dns-packet.c
@@ -0,0 +1,2255 @@
+/***
+ This file is part of systemd.
+
+ Copyright 2014 Lennart Poettering
+
+ systemd is free software; you can redistribute it and/or modify it
+ under the terms of the GNU Lesser General Public License as published by
+ the Free Software Foundation; either version 2.1 of the License, or
+ (at your option) any later version.
+
+ systemd is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ 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 "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;
+ size_t a;
+
+ assert(ret);
+
+ if (mtu <= UDP_PACKET_HEADER_SIZE)
+ a = DNS_PACKET_SIZE_START;
+ else
+ a = mtu - UDP_PACKET_HEADER_SIZE;
+
+ if (a < DNS_PACKET_HEADER_SIZE)
+ a = DNS_PACKET_HEADER_SIZE;
+
+ /* round up to next page size */
+ a = PAGE_ALIGN(ALIGN(sizeof(DnsPacket)) + a) - ALIGN(sizeof(DnsPacket));
+
+ /* make sure we never allocate more than useful */
+ if (a > DNS_PACKET_SIZE_MAX)
+ a = DNS_PACKET_SIZE_MAX;
+
+ p = malloc0(ALIGN(sizeof(DnsPacket)) + a);
+ if (!p)
+ return -ENOMEM;
+
+ 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;
+
+ return 0;
+}
+
+void dns_packet_set_flags(DnsPacket *p, bool dnssec_checking_disabled, bool truncated) {
+
+ DnsPacketHeader *h;
+
+ assert(p);
+
+ h = DNS_PACKET_HEADER(p);
+
+ 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 /* t */,
+ 0 /* ra */,
+ 0 /* ad */,
+ 0 /* cd */,
+ 0 /* rcode */));
+ 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 */,
+ 0 /* tc */,
+ 1 /* rd (ask for recursion) */,
+ 0 /* ra */,
+ 0 /* ad */,
+ dnssec_checking_disabled /* cd */,
+ 0 /* rcode */));
+ }
+}
+
+int dns_packet_new_query(DnsPacket **ret, DnsProtocol protocol, size_t mtu, bool dnssec_checking_disabled) {
+ DnsPacket *p;
+ int r;
+
+ assert(ret);
+
+ r = dns_packet_new(&p, protocol, mtu);
+ if (r < 0)
+ return r;
+
+ /* Always set the TC bit to 0 initially.
+ * If there are multiple packets later, we'll update the bit shortly before sending.
+ */
+ dns_packet_set_flags(p, dnssec_checking_disabled, false);
+
+ *ret = p;
+ return 0;
+}
+
+DnsPacket *dns_packet_ref(DnsPacket *p) {
+
+ if (!p)
+ return NULL;
+
+ assert(!p->on_stack);
+
+ assert(p->n_ref > 0);
+ p->n_ref++;
+ return p;
+}
+
+static void dns_packet_free(DnsPacket *p) {
+ char *s;
+
+ assert(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);
+
+ if (!p->on_stack)
+ free(p);
+}
+
+DnsPacket *dns_packet_unref(DnsPacket *p) {
+ if (!p)
+ return NULL;
+
+ assert(p->n_ref > 0);
+
+ dns_packet_unref(p->more);
+
+ if (p->n_ref == 1)
+ dns_packet_free(p);
+ else
+ p->n_ref--;
+
+ return NULL;
+}
+
+int dns_packet_validate(DnsPacket *p) {
+ assert(p);
+
+ if (p->size < DNS_PACKET_HEADER_SIZE)
+ return -EBADMSG;
+
+ if (p->size > DNS_PACKET_SIZE_MAX)
+ return -EBADMSG;
+
+ return 1;
+}
+
+int dns_packet_validate_reply(DnsPacket *p) {
+ int r;
+
+ assert(p);
+
+ r = dns_packet_validate(p);
+ if (r < 0)
+ return r;
+
+ if (DNS_PACKET_QR(p) != 1)
+ return 0;
+
+ if (DNS_PACKET_OPCODE(p) != 0)
+ 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)
+ return -EBADMSG;
+
+ break;
+
+ case DNS_PROTOCOL_MDNS:
+ /* RFC 6762, Section 18 */
+ if (DNS_PACKET_RCODE(p) != 0)
+ return -EBADMSG;
+
+ break;
+
+ default:
+ break;
+ }
+
+ return 1;
+}
+
+int dns_packet_validate_query(DnsPacket *p) {
+ int r;
+
+ assert(p);
+
+ r = dns_packet_validate(p);
+ if (r < 0)
+ return r;
+
+ if (DNS_PACKET_QR(p) != 0)
+ return 0;
+
+ if (DNS_PACKET_OPCODE(p) != 0)
+ return -EBADMSG;
+
+ if (DNS_PACKET_TC(p))
+ return -EBADMSG;
+
+ switch (p->protocol) {
+
+ case DNS_PROTOCOL_LLMNR:
+ /* RFC 4795, Section 2.1.1. says to discard all queries with QDCOUNT != 1 */
+ if (DNS_PACKET_QDCOUNT(p) != 1)
+ return -EBADMSG;
+
+ /* RFC 4795, Section 2.1.1. says to discard all queries with ANCOUNT != 0 */
+ if (DNS_PACKET_ANCOUNT(p) > 0)
+ return -EBADMSG;
+
+ /* RFC 4795, Section 2.1.1. says to discard all queries with NSCOUNT != 0 */
+ if (DNS_PACKET_NSCOUNT(p) > 0)
+ return -EBADMSG;
+
+ 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 1;
+}
+
+static int dns_packet_extend(DnsPacket *p, size_t add, void **ret, size_t *start) {
+ assert(p);
+
+ if (p->size + add > p->allocated) {
+ size_t a;
+
+ a = PAGE_ALIGN((p->size + add) * 2);
+ if (a > DNS_PACKET_SIZE_MAX)
+ a = DNS_PACKET_SIZE_MAX;
+
+ if (p->size + add > a)
+ return -EMSGSIZE;
+
+ if (p->_data) {
+ void *d;
+
+ d = realloc(p->_data, a);
+ if (!d)
+ return -ENOMEM;
+
+ p->_data = d;
+ } else {
+ p->_data = malloc(a);
+ if (!p->_data)
+ return -ENOMEM;
+
+ memcpy(p->_data, (uint8_t*) p + ALIGN(sizeof(DnsPacket)), p->size);
+ memzero((uint8_t*) p->_data + p->size, a - p->size);
+ }
+
+ p->allocated = a;
+ }
+
+ if (start)
+ *start = p->size;
+
+ if (ret)
+ *ret = (uint8_t*) DNS_PACKET_DATA(p) + p->size;
+
+ p->size += add;
+ return 0;
+}
+
+void dns_packet_truncate(DnsPacket *p, size_t sz) {
+ Iterator i;
+ char *s;
+ void *n;
+
+ assert(p);
+
+ if (p->size <= sz)
+ return;
+
+ HASHMAP_FOREACH_KEY(n, s, p->names, i) {
+
+ if (PTR_TO_SIZE(n) < sz)
+ continue;
+
+ hashmap_remove(p->names, s);
+ free(s);
+ }
+
+ p->size = sz;
+}
+
+int dns_packet_append_blob(DnsPacket *p, const void *d, size_t l, size_t *start) {
+ void *q;
+ int r;
+
+ assert(p);
+
+ r = dns_packet_extend(p, l, &q, start);
+ if (r < 0)
+ return r;
+
+ memcpy(q, d, l);
+ return 0;
+}
+
+int dns_packet_append_uint8(DnsPacket *p, uint8_t v, size_t *start) {
+ void *d;
+ int r;
+
+ assert(p);
+
+ r = dns_packet_extend(p, sizeof(uint8_t), &d, start);
+ if (r < 0)
+ return r;
+
+ ((uint8_t*) d)[0] = v;
+
+ return 0;
+}
+
+int dns_packet_append_uint16(DnsPacket *p, uint16_t v, size_t *start) {
+ void *d;
+ int r;
+
+ assert(p);
+
+ r = dns_packet_extend(p, sizeof(uint16_t), &d, start);
+ if (r < 0)
+ return r;
+
+ unaligned_write_be16(d, v);
+
+ return 0;
+}
+
+int dns_packet_append_uint32(DnsPacket *p, uint32_t v, size_t *start) {
+ void *d;
+ int r;
+
+ assert(p);
+
+ r = dns_packet_extend(p, sizeof(uint32_t), &d, start);
+ if (r < 0)
+ return r;
+
+ unaligned_write_be32(d, v);
+
+ return 0;
+}
+
+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;
+ int r;
+
+ assert(p);
+ assert(s || size == 0);
+
+ if (size > 255)
+ return -E2BIG;
+
+ r = dns_packet_extend(p, 1 + size, &d, start);
+ if (r < 0)
+ return r;
+
+ ((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, 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, (void**) &w, start);
+ if (r < 0)
+ return r;
+
+ *(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,
+ 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 (!dns_name_is_root(name)) {
+ const char *z = name;
+ char label[DNS_LABEL_MAX];
+ size_t n = 0;
+
+ if (allow_compression)
+ n = PTR_TO_SIZE(hashmap_get(p->names, name));
+ if (n > 0) {
+ assert(n < p->size);
+
+ if (n < 0x4000) {
+ r = dns_packet_append_uint16(p, 0xC000 | n, NULL);
+ if (r < 0)
+ goto fail;
+
+ goto done;
+ }
+ }
+
+ r = dns_label_unescape(&name, label, sizeof(label));
+ if (r < 0)
+ goto fail;
+
+ 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;
+
+ r = hashmap_put(p->names, s, SIZE_TO_PTR(n));
+ if (r < 0)
+ goto fail;
+
+ s = NULL;
+ }
+ }
+
+ r = dns_packet_append_uint8(p, 0, NULL);
+ if (r < 0)
+ return r;
+
+done:
+ if (start)
+ *start = saved_size;
+
+ return 0;
+
+fail:
+ dns_packet_truncate(p, saved_size);
+ return r;
+}
+
+int dns_packet_append_key(DnsPacket *p, const DnsResourceKey *k, size_t *start) {
+ size_t saved_size;
+ int r;
+
+ assert(p);
+ assert(k);
+
+ saved_size = p->size;
+
+ r = dns_packet_append_name(p, dns_resource_key_name(k), true, true, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_uint16(p, k->type, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_uint16(p, k->class, NULL);
+ if (r < 0)
+ goto fail;
+
+ if (start)
+ *start = saved_size;
+
+ return 0;
+
+fail:
+ dns_packet_truncate(p, saved_size);
+ return r;
+}
+
+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);
+ assert(length > 0);
+
+ saved_size = p->size;
+
+ r = dns_packet_append_uint8(p, window, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_uint8(p, length, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_blob(p, types, length, NULL);
+ if (r < 0)
+ goto fail;
+
+ if (start)
+ *start = saved_size;
+
+ return 0;
+fail:
+ dns_packet_truncate(p, saved_size);
+ return r;
+}
+
+static int dns_packet_append_types(DnsPacket *p, Bitmap *types, size_t *start) {
+ Iterator i;
+ uint8_t window = 0;
+ uint8_t entry = 0;
+ uint8_t bitmaps[32] = {};
+ unsigned n;
+ size_t saved_size;
+ int r;
+
+ assert(p);
+
+ saved_size = p->size;
+
+ BITMAP_FOREACH(n, types, i) {
+ assert(n <= 0xffff);
+
+ 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;
+
+ zero(bitmaps);
+ }
+
+ window = n >> 8;
+ entry = n & 255;
+
+ bitmaps[entry / 8] |= 1 << (7 - (entry % 8));
+ }
+
+ 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, 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);
+
+ 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;
+
+ /* 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 */
+
+ if (edns0_do) {
+ /* If DO is on, 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_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);
+ assert(rr);
+
+ saved_size = p->size;
+
+ r = dns_packet_append_key(p, rr->key, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_uint32(p, rr->ttl, NULL);
+ if (r < 0)
+ goto fail;
+
+ /* Initially we write 0 here */
+ r = dns_packet_append_uint16(p, 0, &rdlength_offset);
+ if (r < 0)
+ goto fail;
+
+ rds = p->size - saved_size;
+
+ switch (rr->unparseable ? _DNS_TYPE_INVALID : rr->key->type) {
+
+ case DNS_TYPE_SRV:
+ r = dns_packet_append_uint16(p, rr->srv.priority, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_uint16(p, rr->srv.weight, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_uint16(p, rr->srv.port, NULL);
+ if (r < 0)
+ goto fail;
+
+ 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, false, NULL);
+ break;
+
+ case DNS_TYPE_HINFO:
+ r = dns_packet_append_string(p, rr->hinfo.cpu, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_string(p, rr->hinfo.os, NULL);
+ break;
+
+ case DNS_TYPE_SPF: /* exactly the same as TXT */
+ case DNS_TYPE_TXT:
+
+ if (!rr->txt.items) {
+ /* RFC 6763, section 6.1 suggests to generate
+ * single empty string for an empty array. */
+
+ r = dns_packet_append_raw_string(p, NULL, 0, NULL);
+ if (r < 0)
+ goto fail;
+ } else {
+ 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_AAAA:
+ r = dns_packet_append_blob(p, &rr->aaaa.in6_addr, sizeof(struct in6_addr), NULL);
+ break;
+
+ case DNS_TYPE_SOA:
+ 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, false, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_uint32(p, rr->soa.serial, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_uint32(p, rr->soa.refresh, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_uint32(p, rr->soa.retry, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_uint32(p, rr->soa.expire, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_uint32(p, rr->soa.minimum, NULL);
+ break;
+
+ case DNS_TYPE_MX:
+ r = dns_packet_append_uint16(p, rr->mx.priority, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_name(p, rr->mx.exchange, true, false, NULL);
+ break;
+
+ case DNS_TYPE_LOC:
+ r = dns_packet_append_uint8(p, rr->loc.version, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_uint8(p, rr->loc.size, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_uint8(p, rr->loc.horiz_pre, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_uint8(p, rr->loc.vert_pre, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_uint32(p, rr->loc.latitude, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_uint32(p, rr->loc.longitude, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_uint32(p, rr->loc.altitude, NULL);
+ break;
+
+ case DNS_TYPE_DS:
+ r = dns_packet_append_uint16(p, rr->ds.key_tag, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_uint8(p, rr->ds.algorithm, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_uint8(p, rr->ds.digest_type, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_blob(p, rr->ds.digest, rr->ds.digest_size, NULL);
+ break;
+
+ case DNS_TYPE_SSHFP:
+ r = dns_packet_append_uint8(p, rr->sshfp.algorithm, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_uint8(p, rr->sshfp.fptype, NULL);
+ if (r < 0)
+ goto fail;
+
+ 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, rr->dnskey.flags, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_uint8(p, rr->dnskey.protocol, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_uint8(p, rr->dnskey.algorithm, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_blob(p, rr->dnskey.key, rr->dnskey.key_size, NULL);
+ break;
+
+ case DNS_TYPE_RRSIG:
+ r = dns_packet_append_uint16(p, rr->rrsig.type_covered, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_uint8(p, rr->rrsig.algorithm, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_uint8(p, rr->rrsig.labels, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_uint32(p, rr->rrsig.original_ttl, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_uint32(p, rr->rrsig.expiration, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_uint32(p, rr->rrsig.inception, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_uint16(p, rr->rrsig.key_tag, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_name(p, rr->rrsig.signer, false, true, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_blob(p, rr->rrsig.signature, rr->rrsig.signature_size, NULL);
+ break;
+
+ case DNS_TYPE_NSEC:
+ r = dns_packet_append_name(p, rr->nsec.next_domain_name, false, false, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_types(p, rr->nsec.types, NULL);
+ if (r < 0)
+ goto fail;
+
+ break;
+
+ case DNS_TYPE_NSEC3:
+ r = dns_packet_append_uint8(p, rr->nsec3.algorithm, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_uint8(p, rr->nsec3.flags, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_uint16(p, rr->nsec3.iterations, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_uint8(p, rr->nsec3.salt_size, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_blob(p, rr->nsec3.salt, rr->nsec3.salt_size, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_uint8(p, rr->nsec3.next_hashed_name_size, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_blob(p, rr->nsec3.next_hashed_name, rr->nsec3.next_hashed_name_size, NULL);
+ if (r < 0)
+ goto fail;
+
+ r = dns_packet_append_types(p, rr->nsec3.types, 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.data_size, NULL);
+ break;
+ }
+ if (r < 0)
+ goto fail;
+
+ /* Let's calculate the actual data size and update the field */
+ rdlength = p->size - rdlength_offset - sizeof(uint16_t);
+ if (rdlength > 0xFFFF) {
+ r = -ENOSPC;
+ goto fail;
+ }
+
+ end = p->size;
+ p->size = rdlength_offset;
+ r = dns_packet_append_uint16(p, rdlength, NULL);
+ if (r < 0)
+ goto fail;
+ p->size = end;
+
+ if (start)
+ *start = saved_size;
+
+ if (rdata_start)
+ *rdata_start = rds;
+
+ return 0;
+
+fail:
+ dns_packet_truncate(p, saved_size);
+ return r;
+}
+
+int dns_packet_read(DnsPacket *p, size_t sz, const void **ret, size_t *start) {
+ assert(p);
+
+ if (p->rindex + sz > p->size)
+ return -EMSGSIZE;
+
+ if (ret)
+ *ret = (uint8_t*) DNS_PACKET_DATA(p) + p->rindex;
+
+ if (start)
+ *start = p->rindex;
+
+ p->rindex += sz;
+ return 0;
+}
+
+void dns_packet_rewind(DnsPacket *p, size_t idx) {
+ assert(p);
+ assert(idx <= p->size);
+ assert(idx >= DNS_PACKET_HEADER_SIZE);
+
+ p->rindex = idx;
+}
+
+int dns_packet_read_blob(DnsPacket *p, void *d, size_t sz, size_t *start) {
+ const void *q;
+ int r;
+
+ assert(p);
+ assert(d);
+
+ r = dns_packet_read(p, sz, &q, start);
+ if (r < 0)
+ return r;
+
+ memcpy(d, q, sz);
+ 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;
+
+ assert(p);
+
+ r = dns_packet_read(p, sizeof(uint8_t), &d, start);
+ if (r < 0)
+ return r;
+
+ *ret = ((uint8_t*) d)[0];
+ return 0;
+}
+
+int dns_packet_read_uint16(DnsPacket *p, uint16_t *ret, size_t *start) {
+ const void *d;
+ int r;
+
+ assert(p);
+
+ r = dns_packet_read(p, sizeof(uint16_t), &d, start);
+ if (r < 0)
+ return r;
+
+ *ret = unaligned_read_be16(d);
+
+ return 0;
+}
+
+int dns_packet_read_uint32(DnsPacket *p, uint32_t *ret, size_t *start) {
+ const void *d;
+ int r;
+
+ assert(p);
+
+ r = dns_packet_read(p, sizeof(uint32_t), &d, start);
+ if (r < 0)
+ return r;
+
+ *ret = unaligned_read_be32(d);
+
+ return 0;
+}
+
+int dns_packet_read_string(DnsPacket *p, char **ret, size_t *start) {
+ _cleanup_(rewind_dns_packet) DnsPacketRewinder rewinder;
+ const void *d;
+ char *t;
+ 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, &d, NULL);
+ if (r < 0)
+ return r;
+
+ if (memchr(d, 0, c))
+ return -EBADMSG;
+
+ t = strndup(d, c);
+ if (!t)
+ return -ENOMEM;
+
+ if (!utf8_is_valid(t)) {
+ free(t);
+ return -EBADMSG;
+ }
+
+ *ret = t;
+
+ if (start)
+ *start = rewinder.saved_rindex;
+ CANCEL_REWINDER(rewinder);
+
+ return 0;
+}
+
+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) {
+
+ _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;
+ int r;
+
+ assert(p);
+ assert(_ret);
+ 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)
+ return r;
+
+ if (c == 0)
+ /* End of name */
+ break;
+ else if (c <= 63) {
+ const char *label;
+
+ /* Literal label */
+ r = dns_packet_read(p, c, (const void**) &label, NULL);
+ if (r < 0)
+ return r;
+
+ if (!GREEDY_REALLOC(ret, allocated, n + !first + DNS_LABEL_ESCAPED_MAX))
+ return -ENOMEM;
+
+ if (first)
+ first = false;
+ else
+ ret[n++] = '.';
+
+ r = dns_label_escape(label, c, ret + n, DNS_LABEL_ESCAPED_MAX);
+ if (r < 0)
+ return r;
+
+ n += r;
+ continue;
+ } else if (allow_compression && (c & 0xc0) == 0xc0) {
+ uint16_t ptr;
+
+ /* Pointer */
+ r = dns_packet_read_uint8(p, &d, NULL);
+ if (r < 0)
+ return r;
+
+ ptr = (uint16_t) (c & ~0xc0) << 8 | (uint16_t) d;
+ 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
+ return -EBADMSG;
+ }
+
+ if (!GREEDY_REALLOC(ret, allocated, n + 1))
+ return -ENOMEM;
+
+ ret[n] = 0;
+
+ if (after_rindex != 0)
+ p->rindex= after_rindex;
+
+ *_ret = ret;
+ ret = NULL;
+
+ if (start)
+ *start = rewinder.saved_rindex;
+ CANCEL_REWINDER(rewinder);
+
+ return 0;
+}
+
+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;
+ _cleanup_(rewind_dns_packet) DnsPacketRewinder rewinder;
+ int r;
+
+ assert(p);
+ assert(types);
+ INIT_REWINDER(rewinder, p);
+
+ r = bitmap_ensure_allocated(types);
+ if (r < 0)
+ return r;
+
+ r = dns_packet_read_uint8(p, &window, NULL);
+ if (r < 0)
+ return r;
+
+ r = dns_packet_read_uint8(p, &length, NULL);
+ if (r < 0)
+ return r;
+
+ if (length == 0 || length > 32)
+ return -EBADMSG;
+
+ r = dns_packet_read(p, length, (const void **)&bitmap, NULL);
+ if (r < 0)
+ return r;
+
+ for (i = 0; i < length; i++) {
+ uint8_t bitmask = 1 << 7;
+
+ if (!bitmap[i]) {
+ found = false;
+ bit += 8;
+ continue;
+ }
+
+ found = true;
+
+ while (bitmask) {
+ if (bitmap[i] & bitmask) {
+ uint16_t n;
+
+ 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)
+ return r;
+ }
+
+ bit++;
+ bitmask >>= 1;
+ }
+ }
+
+ if (!found)
+ return -EBADMSG;
+
+ if (start)
+ *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;
+}
+
+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;
+ int r;
+
+ assert(p);
+ assert(ret);
+ INIT_REWINDER(rewinder, p);
+
+ r = dns_packet_read_name(p, &name, true, NULL);
+ if (r < 0)
+ return r;
+
+ r = dns_packet_read_uint16(p, &type, NULL);
+ if (r < 0)
+ return r;
+
+ r = dns_packet_read_uint16(p, &class, NULL);
+ if (r < 0)
+ return r;
+
+ 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 = rewinder.saved_rindex;
+ CANCEL_REWINDER(rewinder);
+
+ return 0;
+}
+
+static bool loc_size_ok(uint8_t size) {
+ uint8_t m = size >> 4, e = size & 0xF;
+
+ return m <= 9 && e <= 9 && (m > 0 || e == 0);
+}
+
+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;
+ _cleanup_(rewind_dns_packet) DnsPacketRewinder rewinder;
+ size_t offset;
+ uint16_t rdlength;
+ bool cache_flush;
+ int r;
+
+ assert(p);
+ assert(ret);
+
+ INIT_REWINDER(rewinder, p);
+
+ r = dns_packet_read_key(p, &key, &cache_flush, NULL);
+ if (r < 0)
+ return r;
+
+ 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)
+ return -ENOMEM;
+
+ r = dns_packet_read_uint32(p, &rr->ttl, NULL);
+ if (r < 0)
+ 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)
+ return r;
+
+ if (p->rindex + rdlength > p->size)
+ return -EBADMSG;
+
+ offset = p->rindex;
+
+ switch (rr->key->type) {
+
+ case DNS_TYPE_SRV:
+ r = dns_packet_read_uint16(p, &rr->srv.priority, NULL);
+ if (r < 0)
+ return r;
+ r = dns_packet_read_uint16(p, &rr->srv.weight, NULL);
+ if (r < 0)
+ return r;
+ 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);
+ break;
+
+ case DNS_TYPE_PTR:
+ case DNS_TYPE_NS:
+ case DNS_TYPE_CNAME:
+ case DNS_TYPE_DNAME:
+ r = dns_packet_read_name(p, &rr->ptr.name, true, NULL);
+ break;
+
+ case DNS_TYPE_HINFO:
+ r = dns_packet_read_string(p, &rr->hinfo.cpu, NULL);
+ if (r < 0)
+ return r;
+
+ r = dns_packet_read_string(p, &rr->hinfo.os, NULL);
+ break;
+
+ 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. */
+
+ 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) {
+ DnsTxtItem *i;
+ const void *data;
+ size_t sz;
+
+ r = dns_packet_read_raw_string(p, &data, &sz, NULL);
+ if (r < 0)
+ return r;
+
+ 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;
+ }
+ }
+
+ r = 0;
+ break;
+
+ case DNS_TYPE_A:
+ r = dns_packet_read_blob(p, &rr->a.in_addr, sizeof(struct in_addr), NULL);
+ break;
+
+ case DNS_TYPE_AAAA:
+ r = dns_packet_read_blob(p, &rr->aaaa.in6_addr, sizeof(struct in6_addr), NULL);
+ break;
+
+ case DNS_TYPE_SOA:
+ r = dns_packet_read_name(p, &rr->soa.mname, true, NULL);
+ if (r < 0)
+ return r;
+
+ r = dns_packet_read_name(p, &rr->soa.rname, true, NULL);
+ if (r < 0)
+ return r;
+
+ r = dns_packet_read_uint32(p, &rr->soa.serial, NULL);
+ if (r < 0)
+ return r;
+
+ r = dns_packet_read_uint32(p, &rr->soa.refresh, NULL);
+ if (r < 0)
+ return r;
+
+ r = dns_packet_read_uint32(p, &rr->soa.retry, NULL);
+ if (r < 0)
+ return r;
+
+ r = dns_packet_read_uint32(p, &rr->soa.expire, NULL);
+ if (r < 0)
+ 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)
+ return r;
+
+ r = dns_packet_read_name(p, &rr->mx.exchange, true, NULL);
+ break;
+
+ case DNS_TYPE_LOC: {
+ uint8_t t;
+ size_t pos;
+
+ r = dns_packet_read_uint8(p, &t, &pos);
+ if (r < 0)
+ return r;
+
+ if (t == 0) {
+ rr->loc.version = t;
+
+ r = dns_packet_read_uint8(p, &rr->loc.size, NULL);
+ if (r < 0)
+ return r;
+
+ if (!loc_size_ok(rr->loc.size))
+ return -EBADMSG;
+
+ r = dns_packet_read_uint8(p, &rr->loc.horiz_pre, NULL);
+ if (r < 0)
+ return r;
+
+ if (!loc_size_ok(rr->loc.horiz_pre))
+ return -EBADMSG;
+
+ r = dns_packet_read_uint8(p, &rr->loc.vert_pre, NULL);
+ if (r < 0)
+ return r;
+
+ if (!loc_size_ok(rr->loc.vert_pre))
+ return -EBADMSG;
+
+ r = dns_packet_read_uint32(p, &rr->loc.latitude, NULL);
+ if (r < 0)
+ return r;
+
+ r = dns_packet_read_uint32(p, &rr->loc.longitude, NULL);
+ if (r < 0)
+ return r;
+
+ r = dns_packet_read_uint32(p, &rr->loc.altitude, NULL);
+ if (r < 0)
+ return r;
+
+ break;
+ } else {
+ dns_packet_rewind(p, pos);
+ rr->unparseable = true;
+ goto unparseable;
+ }
+ }
+
+ case DNS_TYPE_DS:
+ r = dns_packet_read_uint16(p, &rr->ds.key_tag, NULL);
+ if (r < 0)
+ return r;
+
+ r = dns_packet_read_uint8(p, &rr->ds.algorithm, NULL);
+ if (r < 0)
+ return r;
+
+ r = dns_packet_read_uint8(p, &rr->ds.digest_type, NULL);
+ if (r < 0)
+ return r;
+
+ r = dns_packet_read_memdup(p, rdlength - 4,
+ &rr->ds.digest, &rr->ds.digest_size,
+ NULL);
+ if (r < 0)
+ 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)
+ return r;
+
+ r = dns_packet_read_uint8(p, &rr->sshfp.fptype, NULL);
+ if (r < 0)
+ return r;
+
+ r = dns_packet_read_memdup(p, rdlength - 2,
+ &rr->sshfp.fingerprint, &rr->sshfp.fingerprint_size,
+ NULL);
+
+ 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;
+
+ break;
+
+ case DNS_TYPE_DNSKEY:
+ r = dns_packet_read_uint16(p, &rr->dnskey.flags, NULL);
+ if (r < 0)
+ return r;
+
+ r = dns_packet_read_uint8(p, &rr->dnskey.protocol, NULL);
+ if (r < 0)
+ return r;
+
+ r = dns_packet_read_uint8(p, &rr->dnskey.algorithm, NULL);
+ if (r < 0)
+ 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;
+
+ break;
+
+ case DNS_TYPE_RRSIG:
+ r = dns_packet_read_uint16(p, &rr->rrsig.type_covered, NULL);
+ if (r < 0)
+ return r;
+
+ r = dns_packet_read_uint8(p, &rr->rrsig.algorithm, NULL);
+ if (r < 0)
+ return r;
+
+ r = dns_packet_read_uint8(p, &rr->rrsig.labels, NULL);
+ if (r < 0)
+ return r;
+
+ r = dns_packet_read_uint32(p, &rr->rrsig.original_ttl, NULL);
+ if (r < 0)
+ return r;
+
+ r = dns_packet_read_uint32(p, &rr->rrsig.expiration, NULL);
+ if (r < 0)
+ return r;
+
+ r = dns_packet_read_uint32(p, &rr->rrsig.inception, NULL);
+ if (r < 0)
+ return r;
+
+ r = dns_packet_read_uint16(p, &rr->rrsig.key_tag, NULL);
+ if (r < 0)
+ return r;
+
+ r = dns_packet_read_name(p, &rr->rrsig.signer, false, NULL);
+ if (r < 0)
+ 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;
+
+ break;
+
+ 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)
+ return r;
+
+ 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
+ * 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)
+ return r;
+
+ r = dns_packet_read_uint8(p, &rr->nsec3.flags, NULL);
+ if (r < 0)
+ return r;
+
+ r = dns_packet_read_uint16(p, &rr->nsec3.iterations, NULL);
+ if (r < 0)
+ return r;
+
+ /* this may be zero */
+ r = dns_packet_read_uint8(p, &size, NULL);
+ if (r < 0)
+ return r;
+
+ r = dns_packet_read_memdup(p, size, &rr->nsec3.salt, &rr->nsec3.salt_size, NULL);
+ if (r < 0)
+ return r;
+
+ r = dns_packet_read_uint8(p, &size, NULL);
+ if (r < 0)
+ return r;
+
+ if (size <= 0)
+ return -EBADMSG;
+
+ r = dns_packet_read_memdup(p, size,
+ &rr->nsec3.next_hashed_name, &rr->nsec3.next_hashed_name_size,
+ NULL);
+ if (r < 0)
+ return r;
+
+ 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;
+ }
+
+ 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.data_size, NULL);
+
+ break;
+ }
+ if (r < 0)
+ 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 = rewinder.saved_rindex;
+ CANCEL_REWINDER(rewinder);
+
+ return 0;
+}
+
+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;
+ _cleanup_(rewind_dns_packet) DnsPacketRewinder rewinder = {};
+ unsigned n, i;
+ int r;
+
+ if (p->extracted)
+ return 0;
+
+ 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)
+ 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, &cache_flush, NULL);
+ if (r < 0)
+ 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)
+ 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)
+ return -ENOMEM;
+
+ for (i = 0; i < n; i++) {
+ _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
+ bool cache_flush;
+
+ r = dns_packet_read_rr(p, &rr, &cache_flush, NULL);
+ if (r < 0)
+ 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 (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;
+ }
+
+ /* 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;
+ question = NULL;
+
+ p->answer = answer;
+ answer = NULL;
+
+ p->extracted = true;
+
+ /* no CANCEL, always rewind */
+ return 0;
+}
+
+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_RCODE_SERVFAIL] = "SERVFAIL",
+ [DNS_RCODE_NXDOMAIN] = "NXDOMAIN",
+ [DNS_RCODE_NOTIMP] = "NOTIMP",
+ [DNS_RCODE_REFUSED] = "REFUSED",
+ [DNS_RCODE_YXDOMAIN] = "YXDOMAIN",
+ [DNS_RCODE_YXRRSET] = "YRRSET",
+ [DNS_RCODE_NXRRSET] = "NXRRSET",
+ [DNS_RCODE_NOTAUTH] = "NOTAUTH",
+ [DNS_RCODE_NOTZONE] = "NOTZONE",
+ [DNS_RCODE_BADVERS] = "BADVERS",
+ [DNS_RCODE_BADKEY] = "BADKEY",
+ [DNS_RCODE_BADTIME] = "BADTIME",
+ [DNS_RCODE_BADMODE] = "BADMODE",
+ [DNS_RCODE_BADNAME] = "BADNAME",
+ [DNS_RCODE_BADALG] = "BADALG",
+ [DNS_RCODE_BADTRUNC] = "BADTRUNC",
+};
+DEFINE_STRING_TABLE_LOOKUP(dns_rcode, int);
+
+static const char* const dns_protocol_table[_DNS_PROTOCOL_MAX] = {
+ [DNS_PROTOCOL_DNS] = "dns",
+ [DNS_PROTOCOL_MDNS] = "mdns",
+ [DNS_PROTOCOL_LLMNR] = "llmnr",
+};
+DEFINE_STRING_TABLE_LOOKUP(dns_protocol, DnsProtocol);
generated by cgit v1.2.3-54-g00ecf (git 2.45.2) at 2024-11-07 06:31:09 +0000