| /*** |
| 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: |
| case DNS_PROTOCOL_DNS: |
| /* RFC 4795, Section 2.1.1. says to discard all queries with QDCOUNT != 1 */ |
| if (DNS_PACKET_QDCOUNT(p) != 1) |
| return -EBADMSG; |
| |
| /* 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, int rcode, size_t *start) { |
| size_t saved_size; |
| int r; |
| |
| assert(p); |
| /* we must never advertise supported packet size smaller than the legacy max */ |
| assert(max_udp_size >= DNS_PACKET_UNICAST_SIZE_MAX); |
| assert(rcode >= 0); |
| assert(rcode <= _DNS_RCODE_MAX); |
| |
| if (p->opt_start != (size_t) -1) |
| return -EBUSY; |
| |
| assert(p->opt_size == (size_t) -1); |
| |
| saved_size = p->size; |
| |
| /* empty name */ |
| r = dns_packet_append_uint8(p, 0, NULL); |
| if (r < 0) |
| return r; |
| |
| /* type */ |
| r = dns_packet_append_uint16(p, DNS_TYPE_OPT, NULL); |
| if (r < 0) |
| goto fail; |
| |
| /* class: maximum udp packet that can be received */ |
| r = dns_packet_append_uint16(p, max_udp_size, NULL); |
| if (r < 0) |
| goto fail; |
| |
| /* extended RCODE and VERSION */ |
| r = dns_packet_append_uint16(p, ((uint16_t) rcode & 0x0FF0) << 4, NULL); |
| if (r < 0) |
| goto fail; |
| |
| /* flags: DNSSEC OK (DO), see RFC3225 */ |
| r = dns_packet_append_uint16(p, edns0_do ? EDNS0_OPT_DO : 0, NULL); |
| if (r < 0) |
| goto fail; |
| |
| /* RDLENGTH */ |
| if (edns0_do && !DNS_PACKET_QR(p)) { |
| /* If DO is on and this is not a reply, also append RFC6975 Algorithm data */ |
| |
| static const uint8_t rfc6975[] = { |
| |
| 0, 5, /* OPTION_CODE: DAU */ |
| 0, 6, /* LIST_LENGTH */ |
| DNSSEC_ALGORITHM_RSASHA1, |
| DNSSEC_ALGORITHM_RSASHA1_NSEC3_SHA1, |
| DNSSEC_ALGORITHM_RSASHA256, |
| DNSSEC_ALGORITHM_RSASHA512, |
| DNSSEC_ALGORITHM_ECDSAP256SHA256, |
| DNSSEC_ALGORITHM_ECDSAP384SHA384, |
| |
| 0, 6, /* OPTION_CODE: DHU */ |
| 0, 3, /* LIST_LENGTH */ |
| DNSSEC_DIGEST_SHA1, |
| DNSSEC_DIGEST_SHA256, |
| DNSSEC_DIGEST_SHA384, |
| |
| 0, 7, /* OPTION_CODE: N3U */ |
| 0, 1, /* LIST_LENGTH */ |
| NSEC3_ALGORITHM_SHA1, |
| }; |
| |
| r = dns_packet_append_uint16(p, sizeof(rfc6975), NULL); |
| if (r < 0) |
| goto fail; |
| |
| r = dns_packet_append_blob(p, rfc6975, sizeof(rfc6975), NULL); |
| } else |
| r = dns_packet_append_uint16(p, 0, NULL); |
| if (r < 0) |
| goto fail; |
| |
| DNS_PACKET_HEADER(p)->arcount = htobe16(DNS_PACKET_ARCOUNT(p) + 1); |
| |
| p->opt_start = saved_size; |
| p->opt_size = p->size - saved_size; |
| |
| if (start) |
| *start = saved_size; |
| |
| return 0; |
| |
| fail: |
| dns_packet_truncate(p, saved_size); |
| return r; |
| } |
| |
| int dns_packet_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_append_question(DnsPacket *p, DnsQuestion *q) { |
| DnsResourceKey *key; |
| int r; |
| |
| assert(p); |
| |
| DNS_QUESTION_FOREACH(key, q) { |
| r = dns_packet_append_key(p, key, NULL); |
| if (r < 0) |
| return r; |
| } |
| |
| return 0; |
| } |
| |
| int dns_packet_append_answer(DnsPacket *p, DnsAnswer *a) { |
| DnsResourceRecord *rr; |
| int r; |
| |
| assert(p); |
| |
| DNS_ANSWER_FOREACH(rr, a) { |
| r = dns_packet_append_rr(p, rr, NULL, NULL); |
| if (r < 0) |
| return r; |
| } |
| |
| return 0; |
| } |
| |
| int dns_packet_read(DnsPacket *p, size_t sz, const void **ret, size_t *start) { |
| assert(p); |
| |
| 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) { |
| *rfc6975 = false; |
| return true; /* if it's not version 0, it's OK, but we will ignore the OPT field contents */ |
| } |
| |
| p = rr->opt.data; |
| l = rr->opt.data_size; |
| while (l > 0) { |
| uint16_t option_code, option_length; |
| |
| /* At least four bytes for OPTION-CODE and OPTION-LENGTH are required */ |
| if (l < 4U) |
| return false; |
| |
| option_code = unaligned_read_be16(p); |
| option_length = unaligned_read_be16(p + 2); |
| |
| if (l < option_length + 4U) |
| return false; |
| |
| /* RFC 6975 DAU, DHU or N3U fields found. */ |
| if (IN_SET(option_code, 5, 6, 7)) |
| found_dau_dhu_n3u = true; |
| |
| p += option_length + 4U; |
| l -= option_length + 4U; |
| } |
| |
| *rfc6975 = found_dau_dhu_n3u; |
| return true; |
| } |
| |
| int dns_packet_extract(DnsPacket *p) { |
| _cleanup_(dns_question_unrefp) DnsQuestion *question = NULL; |
| _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL; |
| _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 = false; |
| |
| 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 (DNS_PACKET_QR(p)) { |
| /* Additional checks for responses */ |
| |
| if (!DNS_RESOURCE_RECORD_OPT_VERSION_SUPPORTED(rr)) { |
| /* If this is a reply and we don't know the EDNS version then something |
| * is weird... */ |
| log_debug("EDNS version newer that our request, bad server."); |
| return -EBADMSG; |
| } |
| |
| if (has_rfc6975) { |
| /* If the OPT RR contains RFC6975 algorithm data, then this is indication that |
| * the server just copied the OPT it got from us (which contained that data) |
| * back into the reply. If so, then it doesn't properly support EDNS, as |
| * RFC6975 makes it very clear that the algorithm data should only be contained |
| * in questions, never in replies. Crappy Belkin routers copy the OPT data for |
| * example, hence let's detect this so that we downgrade early. */ |
| log_debug("OPT RR contained RFC6975 data, ignoring."); |
| bad_opt = true; |
| continue; |
| } |
| } |
| |
| p->opt = dns_resource_record_ref(rr); |
| } else { |
| |
| /* According to RFC 4795, section 2.9. only the RRs from the Answer section shall be |
| * cached. Hence mark only those RRs as cacheable by default, but not the ones from the |
| * Additional or Authority sections. */ |
| |
| r = dns_answer_add(answer, rr, p->ifindex, |
| (i < DNS_PACKET_ANCOUNT(p) ? DNS_ANSWER_CACHEABLE : 0) | |
| (p->protocol == DNS_PROTOCOL_MDNS && !cache_flush ? DNS_ANSWER_SHARED_OWNER : 0)); |
| if (r < 0) |
| return r; |
| } |
| |
| /* 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", |
| [DNS_RCODE_BADCOOKIE] = "BADCOOKIE", |
| }; |
| 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); |