X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=src%2Fresolve%2Fresolved-dns-packet.c;h=5d4e097c7589346b42e34d9dcea192c060c1d051;hp=e5a4a403411e332fd220737585de5642921ffd20;hb=8ac4e9e1e54397f6d1745c2a7a806132418c7da2;hpb=7e8e0422aeb16f2a09a40546c61df753d10029b6 diff --git a/src/resolve/resolved-dns-packet.c b/src/resolve/resolved-dns-packet.c index e5a4a4034..5d4e097c7 100644 --- a/src/resolve/resolved-dns-packet.c +++ b/src/resolve/resolved-dns-packet.c @@ -21,6 +21,7 @@ #include "utf8.h" #include "util.h" +#include "strv.h" #include "resolved-dns-domain.h" #include "resolved-dns-packet.h" @@ -72,10 +73,26 @@ int dns_packet_new_query(DnsPacket **ret, DnsProtocol protocol, size_t mtu) { h = DNS_PACKET_HEADER(p); - if (protocol == DNS_PROTOCOL_DNS) - h->flags = htobe16(DNS_PACKET_MAKE_FLAGS(0, 0, 0, 0, 1, 0, 0, 0, 0)); /* ask for recursion */ + if (protocol == DNS_PROTOCOL_LLMNR) + 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 */)); else - h->flags = htobe16(DNS_PACKET_MAKE_FLAGS(0, 0, 0, 0, 0, 0, 0, 0, 0)); + h->flags = htobe16(DNS_PACKET_MAKE_FLAGS(0 /* qr */, + 0 /* opcode */, + 0 /* aa */, + 0 /* tc */, + 1 /* rd (ask for recursion) */, + 0 /* ra */, + 0 /* ad */, + 0 /* cd */, + 0 /* rcode */)); *ret = p; return 0; @@ -130,7 +147,7 @@ int dns_packet_validate(DnsPacket *p) { if (p->size > DNS_PACKET_SIZE_MAX) return -EBADMSG; - return 0; + return 1; } int dns_packet_validate_reply(DnsPacket *p) { @@ -142,13 +159,52 @@ int dns_packet_validate_reply(DnsPacket *p) { if (r < 0) return r; - if (DNS_PACKET_QR(p) == 0) + if (DNS_PACKET_QR(p) != 1) + return 0; + + if (DNS_PACKET_OPCODE(p) != 0) return -EBADMSG; + /* RFC 4795, Section 2.1.1. says to discard all replies with QDCOUNT != 1 */ + if (p->protocol == DNS_PROTOCOL_LLMNR && + DNS_PACKET_QDCOUNT(p) != 1) + return -EBADMSG; + + 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; - return 0; + if (DNS_PACKET_TC(p)) + return -EBADMSG; + + /* RFC 4795, Section 2.1.1. says to discard all queries with QDCOUNT != 1 */ + if (p->protocol == DNS_PROTOCOL_LLMNR && + 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; + + return 1; } static int dns_packet_extend(DnsPacket *p, size_t add, void **ret, size_t *start) { @@ -216,6 +272,20 @@ static void dns_packet_truncate(DnsPacket *p, size_t sz) { 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; @@ -242,7 +312,25 @@ int dns_packet_append_uint16(DnsPacket *p, uint16_t v, size_t *start) { return r; ((uint8_t*) d)[0] = (uint8_t) (v >> 8); - ((uint8_t*) d)[1] = (uint8_t) (v & 255); + ((uint8_t*) d)[1] = (uint8_t) 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; + + ((uint8_t*) d)[0] = (uint8_t) (v >> 24); + ((uint8_t*) d)[1] = (uint8_t) (v >> 16); + ((uint8_t*) d)[2] = (uint8_t) (v >> 8); + ((uint8_t*) d)[3] = (uint8_t) v; return 0; } @@ -387,6 +475,166 @@ fail: return r; } +int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *start) { + size_t saved_size, rdlength_offset, end, rdlength; + 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; + + switch (rr->unparseable ? _DNS_TYPE_INVALID : rr->key->type) { + + 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, 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: { + char **s; + + STRV_FOREACH(s, rr->txt.strings) { + r = dns_packet_append_string(p, *s, NULL); + if (r < 0) + goto fail; + } + + 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, NULL); + if (r < 0) + goto fail; + + r = dns_packet_append_name(p, rr->soa.rname, 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, 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_uint16(p, rr->loc.latitude, NULL); + if (r < 0) + goto fail; + + r = dns_packet_append_uint16(p, rr->loc.longitude, NULL); + if (r < 0) + goto fail; + + r = dns_packet_append_uint16(p, rr->loc.altitude, NULL); + break; + + case DNS_TYPE_SRV: + case DNS_TYPE_SSHFP: + case _DNS_TYPE_INVALID: /* unparseable */ + default: + + r = dns_packet_append_blob(p, rr->generic.data, rr->generic.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; + + 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); @@ -411,6 +659,21 @@ void dns_packet_rewind(DnsPacket *p, size_t idx) { 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; +} + int dns_packet_read_uint8(DnsPacket *p, uint8_t *ret, size_t *start) { const void *d; int r; @@ -658,6 +921,12 @@ int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start) { if (r < 0) goto fail; + if (key->class == DNS_CLASS_ANY || + key->type == DNS_TYPE_ANY) { + r = -EBADMSG; + goto fail; + } + rr = dns_resource_record_new(key); if (!rr) { r = -ENOMEM; @@ -684,6 +953,7 @@ int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start) { 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, NULL); break; @@ -695,20 +965,28 @@ int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start) { r = dns_packet_read_string(p, &rr->hinfo.os, NULL); break; - case DNS_TYPE_A: - r = dns_packet_read(p, sizeof(struct in_addr), &d, NULL); - if (r < 0) - goto fail; + case DNS_TYPE_SPF: /* exactly the same as TXT */ + case DNS_TYPE_TXT: { + char *s; + + while (p->rindex < offset + rdlength) { + r = dns_packet_read_string(p, &s, NULL); + if (r < 0) + goto fail; + + r = strv_consume(&rr->txt.strings, s); + if (r < 0) + goto fail; + }; + break; + } - memcpy(&rr->a.in_addr, d, sizeof(struct in_addr)); + 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(p, sizeof(struct in6_addr), &d, NULL); - if (r < 0) - goto fail; - - memcpy(&rr->aaaa.in6_addr, d, sizeof(struct in6_addr)); + r = dns_packet_read_blob(p, &rr->aaaa.in6_addr, sizeof(struct in6_addr), NULL); break; case DNS_TYPE_SOA: @@ -739,6 +1017,59 @@ int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start) { r = dns_packet_read_uint32(p, &rr->soa.minimum, NULL); break; + case DNS_TYPE_MX: + r = dns_packet_read_uint16(p, &rr->mx.priority, NULL); + if (r < 0) + goto fail; + + r = dns_packet_read_name(p, &rr->mx.exchange, NULL); + break; + + case DNS_TYPE_LOC: { + uint8_t t; + size_t pos; + + r = dns_packet_read_uint8(p, &t, &pos); + if (r < 0) + goto fail; + + if (t == 0) { + rr->loc.version = t; + + r = dns_packet_read_uint8(p, &rr->loc.size, NULL); + if (r < 0) + goto fail; + + r = dns_packet_read_uint8(p, &rr->loc.horiz_pre, NULL); + if (r < 0) + goto fail; + + r = dns_packet_read_uint8(p, &rr->loc.vert_pre, NULL); + if (r < 0) + goto fail; + + r = dns_packet_read_uint32(p, &rr->loc.latitude, NULL); + if (r < 0) + goto fail; + + r = dns_packet_read_uint32(p, &rr->loc.longitude, NULL); + if (r < 0) + goto fail; + + r = dns_packet_read_uint32(p, &rr->loc.altitude, NULL); + if (r < 0) + goto fail; + + break; + } else { + dns_packet_rewind(p, pos); + rr->unparseable = true; + /* fall through */ + } + } + + case DNS_TYPE_SRV: + case DNS_TYPE_SSHFP: default: r = dns_packet_read(p, rdlength, &d, NULL); if (r < 0)