diff options
Diffstat (limited to 'src/resolve/resolved-dns-packet.c')
| -rw-r--r-- | src/resolve/resolved-dns-packet.c | 123 |
1 files changed, 91 insertions, 32 deletions
diff --git a/src/resolve/resolved-dns-packet.c b/src/resolve/resolved-dns-packet.c index f23b3cf893..40b662246f 100644 --- a/src/resolve/resolved-dns-packet.c +++ b/src/resolve/resolved-dns-packet.c @@ -370,6 +370,28 @@ int dns_packet_append_string(DnsPacket *p, const char *s, size_t *start) { return 0; } +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; + + if (size > 0) + memcpy(((uint8_t*) d) + 1, s, size); + + return 0; +} + int dns_packet_append_label(DnsPacket *p, const char *d, size_t l, size_t *start) { void *w; int r; @@ -643,19 +665,20 @@ int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *star break; case DNS_TYPE_SPF: /* exactly the same as TXT */ - case DNS_TYPE_TXT: { - char **s; + case DNS_TYPE_TXT: - if (strv_isempty(rr->txt.strings)) { + if (!rr->txt.items) { /* RFC 6763, section 6.1 suggests to generate * single empty string for an empty array. */ - r = dns_packet_append_string(p, "", NULL); + r = dns_packet_append_raw_string(p, NULL, 0, NULL); if (r < 0) goto fail; } else { - STRV_FOREACH(s, rr->txt.strings) { - r = dns_packet_append_string(p, *s, NULL); + 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; } @@ -663,7 +686,6 @@ int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *star r = 0; break; - } case DNS_TYPE_A: r = dns_packet_append_blob(p, &rr->a.in_addr, sizeof(struct in_addr), NULL); @@ -1062,6 +1084,35 @@ fail: return r; } +int dns_packet_read_raw_string(DnsPacket *p, const void **ret, size_t *size, size_t *start) { + size_t saved_rindex; + uint8_t c; + int r; + + assert(p); + + saved_rindex = p->rindex; + + r = dns_packet_read_uint8(p, &c, NULL); + if (r < 0) + goto fail; + + r = dns_packet_read(p, c, ret, NULL); + if (r < 0) + goto fail; + + if (size) + *size = c; + if (start) + *start = saved_rindex; + + return 0; + +fail: + dns_packet_rewind(p, saved_rindex); + return r; +} + int dns_packet_read_name( DnsPacket *p, char **_ret, @@ -1094,7 +1145,6 @@ int dns_packet_read_name( /* End of name */ break; else if (c <= 63) { - _cleanup_free_ char *t = NULL; const char *label; /* Literal label */ @@ -1102,21 +1152,20 @@ int dns_packet_read_name( if (r < 0) goto fail; - r = dns_label_escape(label, c, &t); - if (r < 0) - goto fail; - - if (!GREEDY_REALLOC(ret, allocated, n + !first + strlen(t) + 1)) { + if (!GREEDY_REALLOC(ret, allocated, n + !first + DNS_LABEL_ESCAPED_MAX)) { r = -ENOMEM; goto fail; } - if (!first) - ret[n++] = '.'; - else + if (first) first = false; + else + ret[n++] = '.'; + + r = dns_label_escape(label, c, ret + n, DNS_LABEL_ESCAPED_MAX); + if (r < 0) + goto fail; - memcpy(ret + n, t, r); n += r; continue; } else if (allow_compression && (c & 0xc0) == 0xc0) { @@ -1412,24 +1461,37 @@ int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start) { 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. */ - r = strv_extend(&rr->txt.strings, ""); - if (r < 0) - goto fail; + 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) { - char *s; + DnsTxtItem *i; + const void *data; + size_t sz; - r = dns_packet_read_string(p, &s, NULL); + r = dns_packet_read_raw_string(p, &data, &sz, NULL); if (r < 0) - goto fail; + return r; - r = strv_consume(&rr->txt.strings, s); - if (r < 0) - goto fail; + 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; } } @@ -1682,12 +1744,9 @@ int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start) { if (r < 0) goto fail; - /* The types bitmap must contain at least the NSEC record itself, so an empty bitmap means - something went wrong */ - if (bitmap_isclear(rr->nsec.types)) { - r = -EBADMSG; - goto fail; - } + /* We accept empty NSEC bitmaps. The bit indicating the presence of the NSEC record itself + * is redundant and in e.g., RFC4956 this fact is used to define a use for NSEC records + * without the NSEC bit set. */ break; |