Revision 47, 2022-12-16 11:26:53 +0100 (Fri, 16 Dec 2022)
This commit is contained in:
Jeroen Janssen
commit
7df7cb0b6d
7 changed files with 4275 additions and 0 deletions
295
unpack_dns.c
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295
unpack_dns.c
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/* $OpenBSD: unpack_dns.c,v 1.1 2018/01/06 07:57:53 sunil Exp $ */
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/*
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* Copyright (c) 2011-2014 Eric Faurot <eric@faurot.net>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include <arpa/inet.h>
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#include <string.h>
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#include "unpack_dns.h"
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static int unpack_data(struct unpack *, void *, size_t);
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static int unpack_u16(struct unpack *, uint16_t *);
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static int unpack_u32(struct unpack *, uint32_t *);
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static int unpack_inaddr(struct unpack *, struct in_addr *);
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static int unpack_in6addr(struct unpack *, struct in6_addr *);
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static int unpack_dname(struct unpack *, char *, size_t);
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void
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unpack_init(struct unpack *unpack, const char *buf, size_t len)
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{
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unpack->buf = buf;
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unpack->len = len;
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unpack->offset = 0;
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unpack->err = NULL;
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}
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int
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unpack_header(struct unpack *p, struct dns_header *h)
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{
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if (unpack_data(p, h, HFIXEDSZ) == -1)
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return (-1);
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h->flags = ntohs(h->flags);
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h->qdcount = ntohs(h->qdcount);
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h->ancount = ntohs(h->ancount);
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h->nscount = ntohs(h->nscount);
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h->arcount = ntohs(h->arcount);
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return (0);
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}
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int
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unpack_query(struct unpack *p, struct dns_query *q)
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{
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unpack_dname(p, q->q_dname, sizeof(q->q_dname));
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unpack_u16(p, &q->q_type);
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unpack_u16(p, &q->q_class);
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return (p->err) ? (-1) : (0);
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}
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int
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unpack_rr(struct unpack *p, struct dns_rr *rr)
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{
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uint16_t rdlen;
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size_t save_offset;
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unpack_dname(p, rr->rr_dname, sizeof(rr->rr_dname));
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unpack_u16(p, &rr->rr_type);
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unpack_u16(p, &rr->rr_class);
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unpack_u32(p, &rr->rr_ttl);
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unpack_u16(p, &rdlen);
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if (p->err)
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return (-1);
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if (p->len - p->offset < rdlen) {
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p->err = "too short";
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return (-1);
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}
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save_offset = p->offset;
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switch (rr->rr_type) {
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case T_CNAME:
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unpack_dname(p, rr->rr.cname.cname, sizeof(rr->rr.cname.cname));
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break;
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case T_MX:
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unpack_u16(p, &rr->rr.mx.preference);
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unpack_dname(p, rr->rr.mx.exchange, sizeof(rr->rr.mx.exchange));
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break;
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case T_NS:
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unpack_dname(p, rr->rr.ns.nsname, sizeof(rr->rr.ns.nsname));
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break;
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case T_PTR:
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unpack_dname(p, rr->rr.ptr.ptrname, sizeof(rr->rr.ptr.ptrname));
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break;
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case T_SOA:
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unpack_dname(p, rr->rr.soa.mname, sizeof(rr->rr.soa.mname));
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unpack_dname(p, rr->rr.soa.rname, sizeof(rr->rr.soa.rname));
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unpack_u32(p, &rr->rr.soa.serial);
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unpack_u32(p, &rr->rr.soa.refresh);
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unpack_u32(p, &rr->rr.soa.retry);
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unpack_u32(p, &rr->rr.soa.expire);
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unpack_u32(p, &rr->rr.soa.minimum);
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break;
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case T_A:
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if (rr->rr_class != C_IN)
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goto other;
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unpack_inaddr(p, &rr->rr.in_a.addr);
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break;
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case T_AAAA:
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if (rr->rr_class != C_IN)
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goto other;
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unpack_in6addr(p, &rr->rr.in_aaaa.addr6);
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break;
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default:
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other:
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rr->rr.other.rdata = p->buf + p->offset;
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rr->rr.other.rdlen = rdlen;
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p->offset += rdlen;
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}
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if (p->err)
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return (-1);
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/* make sure that the advertised rdlen is really ok */
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if (p->offset - save_offset != rdlen)
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p->err = "bad dlen";
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return (p->err) ? (-1) : (0);
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}
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ssize_t
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dname_expand(const unsigned char *data, size_t len, size_t offset,
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size_t *newoffset, char *dst, size_t max)
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{
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size_t n, count, end, ptr, start;
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ssize_t res;
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if (offset >= len)
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return (-1);
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res = 0;
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end = start = offset;
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for (; (n = data[offset]); ) {
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if ((n & 0xc0) == 0xc0) {
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if (offset + 2 > len)
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return (-1);
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ptr = 256 * (n & ~0xc0) + data[offset + 1];
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if (ptr >= start)
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return (-1);
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if (end < offset + 2)
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end = offset + 2;
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offset = start = ptr;
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continue;
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}
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if (offset + n + 1 > len)
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return (-1);
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/* copy n + at offset+1 */
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if (dst != NULL && max != 0) {
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count = (max < n + 1) ? (max) : (n + 1);
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memmove(dst, data + offset, count);
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dst += count;
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max -= count;
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}
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res += n + 1;
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offset += n + 1;
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if (end < offset)
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end = offset;
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}
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if (end < offset + 1)
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end = offset + 1;
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if (dst != NULL && max != 0)
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dst[0] = 0;
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if (newoffset)
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*newoffset = end;
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return (res + 1);
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}
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char *
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print_dname(const char *_dname, char *buf, size_t max)
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{
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const unsigned char *dname = _dname;
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char *res;
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size_t left, count;
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if (_dname[0] == 0) {
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(void)strlcpy(buf, ".", max);
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return buf;
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}
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res = buf;
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left = max - 1;
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for (; dname[0] && left;) {
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count = (dname[0] < (left - 1)) ? dname[0] : (left - 1);
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memmove(buf, dname + 1, count);
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dname += dname[0] + 1;
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left -= count;
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buf += count;
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if (left) {
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left -= 1;
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*buf++ = '.';
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}
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}
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buf[0] = 0;
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return (res);
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}
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static int
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unpack_data(struct unpack *p, void *data, size_t len)
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{
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if (p->err)
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return (-1);
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if (p->len - p->offset < len) {
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p->err = "too short";
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return (-1);
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}
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memmove(data, p->buf + p->offset, len);
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p->offset += len;
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return (0);
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}
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static int
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unpack_u16(struct unpack *p, uint16_t *u16)
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{
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if (unpack_data(p, u16, 2) == -1)
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return (-1);
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*u16 = ntohs(*u16);
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return (0);
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}
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static int
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unpack_u32(struct unpack *p, uint32_t *u32)
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{
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if (unpack_data(p, u32, 4) == -1)
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return (-1);
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*u32 = ntohl(*u32);
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return (0);
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}
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static int
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unpack_inaddr(struct unpack *p, struct in_addr *a)
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{
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return (unpack_data(p, a, 4));
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}
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static int
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unpack_in6addr(struct unpack *p, struct in6_addr *a6)
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{
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return (unpack_data(p, a6, 16));
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}
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static int
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unpack_dname(struct unpack *p, char *dst, size_t max)
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{
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ssize_t e;
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if (p->err)
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return (-1);
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e = dname_expand(p->buf, p->len, p->offset, &p->offset, dst, max);
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if (e == -1) {
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p->err = "bad domain name";
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return (-1);
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}
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if (e < 0 || e > MAXDNAME) {
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p->err = "domain name too long";
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return (-1);
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}
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return (0);
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}
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