diff options
Diffstat (limited to 'contrib/librdns/packet.c')
| -rw-r--r-- | contrib/librdns/packet.c | 271 |
1 files changed, 271 insertions, 0 deletions
diff --git a/contrib/librdns/packet.c b/contrib/librdns/packet.c new file mode 100644 index 000000000..88e51dfba --- /dev/null +++ b/contrib/librdns/packet.c @@ -0,0 +1,271 @@ +/* Copyright (c) 2014, Vsevolod Stakhov + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are met: + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * * Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED ''AS IS'' AND ANY + * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED + * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE + * DISCLAIMED. IN NO EVENT SHALL AUTHOR BE LIABLE FOR ANY + * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND + * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#include "rdns.h" +#include "dns_private.h" +#include "punycode.h" +#include "packet.h" +#include "util.h" +#include "logger.h" +#include "compression.h" + +void +rdns_allocate_packet (struct rdns_request* req, unsigned int namelen) +{ + namelen += 96 + 2 + 4 + 11; /* EDNS0 RR */ + req->packet = malloc (namelen); + req->pos = 0; + req->packet_len = namelen; +} + + +void +rdns_make_dns_header (struct rdns_request *req, unsigned int qcount) +{ + struct dns_header *header; + + /* Set DNS header values */ + header = (struct dns_header *)req->packet; + memset (header, 0 , sizeof (struct dns_header)); + header->qid = rdns_permutor_generate_id (); + header->rd = 1; + header->qdcount = htons (qcount); + header->arcount = htons (1); + req->pos += sizeof (struct dns_header); + req->id = header->qid; +} + +static bool +rdns_maybe_punycode_label (const uint8_t *begin, + uint8_t const **dot, size_t *label_len) +{ + bool ret = false; + const uint8_t *p = begin; + + *dot = NULL; + + while (*p) { + if (*p == '.') { + *dot = p; + break; + } + else if ((*p) & 0x80) { + ret = true; + } + p ++; + } + + if (*p) { + *label_len = p - begin; + } + else { + *label_len = p - begin; + } + + return ret; +} + +bool +rdns_format_dns_name (struct rdns_resolver *resolver, const char *in, + size_t inlen, + char **out, size_t *outlen) +{ + const uint8_t *dot; + const uint8_t *p = in, *end = in + inlen; + char *o; + int labels = 0; + size_t label_len, olen, remain; + uint32_t *uclabel; + size_t punylabel_len, uclabel_len; + char tmp_label[DNS_D_MAXLABEL]; + bool need_encode = false; + + if (inlen == 0) { + inlen = strlen (in); + } + + /* Check for non-ascii characters */ + while (p != end) { + if (*p >= 0x80) { + need_encode = true; + } + else if (*p == '.') { + labels ++; + } + p ++; + } + + if (!need_encode) { + *out = malloc (inlen + 1); + if (*out == NULL) { + return false; + } + o = *out; + memcpy (o, in, inlen); + o[inlen] = '\0'; + *outlen = inlen; + + return true; + } + + /* We need to encode */ + + p = in; + olen = inlen + 1 + sizeof ("xn--") * labels; + *out = malloc (olen); + + if (*out == NULL) { + return false; + } + + o = *out; + remain = olen; + + while (p != end) { + /* Check label for unicode characters */ + if (rdns_maybe_punycode_label (p, &dot, &label_len)) { + /* Convert to ucs4 */ + if (rdns_utf8_to_ucs4 (p, label_len, &uclabel, &uclabel_len) == 0) { + punylabel_len = DNS_D_MAXLABEL; + + rdns_punycode_label_toascii (uclabel, uclabel_len, + tmp_label, &punylabel_len); + if (remain >= punylabel_len + 1) { + memcpy (o, tmp_label, punylabel_len); + o += punylabel_len; + *o++ = '.'; + remain -= punylabel_len + 1; + } + else { + rdns_info ("no buffer remain for punycoding query"); + free (*out); + return false; + } + + free (uclabel); + + if (dot) { + p = dot + 1; + } + else { + break; + } + } + else { + break; + } + } + else { + if (dot) { + if (label_len > DNS_D_MAXLABEL) { + rdns_info ("dns name component is longer than 63 bytes, should be stripped"); + label_len = DNS_D_MAXLABEL; + } + if (remain < label_len + 1) { + rdns_info ("no buffer remain for punycoding query"); + return false; + } + if (label_len == 0) { + /* Two dots in order, skip this */ + rdns_info ("name contains two or more dots in a row, replace it with one dot"); + p = dot + 1; + continue; + } + memcpy (o, p, label_len); + o += label_len; + *o++ = '.'; + remain -= label_len + 1; + p = dot + 1; + } + else { + if (label_len == 0) { + /* If name is ended with dot */ + break; + } + if (label_len > DNS_D_MAXLABEL) { + rdns_info ("dns name component is longer than 63 bytes, should be stripped"); + label_len = DNS_D_MAXLABEL; + } + if (remain < label_len + 1) { + rdns_info ("no buffer remain for punycoding query"); + return false; + } + memcpy (o, p, label_len); + o += label_len; + *o++ = '.'; + remain -= label_len + 1; + p = dot + 1; + break; + } + } + if (remain == 0) { + rdns_info ("no buffer remain for punycoding query"); + return false; + } + } + *o = '\0'; + + *outlen = o - *out; + + return true; +} + +bool +rdns_add_rr (struct rdns_request *req, const char *name, unsigned int len, + enum dns_type type, struct rdns_compression_entry **comp) +{ + uint16_t *p; + + if (!rdns_write_name_compressed (req, name, len, comp)) { + return false; + } + p = (uint16_t *)(req->packet + req->pos); + *p++ = htons (type); + *p = htons (DNS_C_IN); + req->pos += sizeof (uint16_t) * 2; + + return true; +} + +bool +rdns_add_edns0 (struct rdns_request *req) +{ + uint8_t *p8; + uint16_t *p16; + + p8 = (uint8_t *)(req->packet + req->pos); + *p8 = '\0'; /* Name is root */ + p16 = (uint16_t *)(req->packet + req->pos + 1); + *p16++ = htons (DNS_T_OPT); + /* UDP packet length */ + *p16++ = htons (UDP_PACKET_SIZE); + /* Extended rcode 00 00 */ + *p16++ = 0; + /* Z 10000000 00000000 to allow dnssec, disabled currently */ + *p16++ = 0; + /* Length */ + *p16 = 0; + req->pos += sizeof (uint8_t) + sizeof (uint16_t) * 5; + + return true; +} |