#include "open62541/config.h"

/* Standalone DNS parsing, RFC10350

 *

 * Copyright (c) 2003  Jeremie Miller <jer@jabber.org>

 * Copyright (c) 2016-2022  Joachim Wiberg <troglobit@gmail.com>

 * 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.

 *     * Neither the name of the copyright holders nor the names of its

 *       contributors may be used to endorse or promote products derived from

 *       this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 THE COPYRIGHT HOLDERS OR CONTRIBUTORS 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 "1035.h"

#include <string.h>

#include <stdio.h>

unsigned short int net2short(unsigned char **bufp)

{

  unsigned short int i;

  i = **bufp;

  i <<= 8;

  i |= *(*bufp + 1);

  *bufp += 2;

  return i;

}

unsigned long int net2long(unsigned char **bufp)

{

  long int l;

  l = **bufp;

  l <<= 8;

  l |= *(*bufp + 1);

  l <<= 8;

  l |= *(*bufp + 2);

  l <<= 8;

  l |= *(*bufp + 3);

  *bufp += 4;

  return l;

}

void short2net(unsigned short int i, unsigned char **bufp)

{

  *(*bufp + 1) = (unsigned char)i;

  i >>= 8;

  **bufp = (unsigned char)i;

  *bufp += 2;

}

void long2net(unsigned long int l, unsigned char **bufp)

{

  *(*bufp + 3) = (unsigned char)l;

  l >>= 8;

  *(*bufp + 2) = (unsigned char)l;

  l >>= 8;

  *(*bufp + 1) = (unsigned char)l;

  l >>= 8;

  **bufp = (unsigned char)l;

  *bufp += 4;

}

static unsigned short int _ldecomp(const char *ptr)

{

  unsigned short int i;

  i = 0xc0 ^ ptr[0];

  i <<= 8;

  i |= (unsigned char)ptr[1];

  if (i >= 4096)

    i = 4095;

  return i;

}

static int _label(struct message *m, unsigned char **bufp, char **namep)

{

  int x;

  char *label, *name;

  /* Sanity check */

  if (m->_len > (int)sizeof(m->_packet))

    return 1;

  /* Set namep to the end of the block */

  *namep = name = (char *)m->_packet + m->_len;

  /* Loop storing label in the block */

  for (label = (char *)*bufp; *label != 0; name += *label + 1, label += *label + 1) {

    /* Skip past any compression pointers, kick out if end encountered (bad data prolly) */

    int prevOffset = -1;

    while (*label & 0xc0) {

      unsigned short int offset = _ldecomp(label);

      if (offset <= prevOffset || offset > m->_len)

        return 1;

      if (*(label = (char *)m->_buf + offset) == 0)

        break;

      prevOffset = offset;

    }

    /* Make sure we're not over the limits */

    if ((name + *label) - *namep > 255 || m->_len + ((name + *label) - *namep) >= MAX_PACKET_LEN)

      return 1;

    /* Copy chars for this label */

    memcpy(name, label + 1, (size_t)*label);

    name[(size_t)*label] = '.';

  }

  /* Advance buffer */

  for (label = (char *)*bufp; *label != 0 && !(*label & 0xc0 && label++); label += *label + 1)

    ;

  *bufp = (unsigned char *)(label + 1);

  /* Terminate name and check for cache or cache it */

  *name = '\0';

  for (x = 0; x < MAX_NUM_LABELS && m->_labels[x]; x++) {

    if (strcmp(*namep, m->_labels[x]))

      continue;

    *namep = m->_labels[x];

    return 0;

  }

  /* No cache, so cache it if room */

  if (x < MAX_NUM_LABELS && m->_labels[x] == 0)

    m->_labels[x] = *namep;

  m->_len += (int)(name - *namep) + 1;

  return 0;

}

/* Internal label matching */

static int _lmatch(const struct message *m, const char *l1, const char *l2)

{

  int len;

  /* Always ensure we get called w/o a pointer */

  if (*l1 & 0xc0)

    return _lmatch(m, (char *)m->_buf + _ldecomp(l1), l2);

  if (*l2 & 0xc0)

    return _lmatch(m, l1, (char *)m->_buf + _ldecomp(l2));

  /* Same already? */

  if (l1 == l2)

    return 1;

  /* Compare all label characters */

  if (*l1 != *l2)

    return 0;

  for (len = 1; len <= *l1; len++) {

    if (l1[len] != l2[len])

      return 0;

  }

  /* Get new_ labels */

  l1 += *l1 + 1;

  l2 += *l2 + 1;

  /* At the end, all matched */

  if (*l1 == 0 && *l2 == 0)

    return 1;

  /* Try next labels */

  return _lmatch(m, l1, l2);

}

/* Nasty, convert host into label using compression */

static int _host(struct message *m, unsigned char **bufp, const char *name)

{

  char label[256], *l;

  int len = 0, x = 1, y = 0, last = 0;

  if (name == 0)

    return 0;

  /* Make our label */

  while (name[y]) {

    if (name[y] == '.') {

      if (!name[y + 1])

        break;

      label[last] = (char)(x - (last + 1));

      last = x;

    } else {

      label[x] = name[y];

    }

    if (x++ == 255)

      return 0;

    y++;

  }

  label[last] = (char)(x - (last + 1));

  if (x == 1)

    x--;   /* Special case, bad names, but handle correctly */

  len = x + 1;

  label[x] = 0;   /* Always terminate w/ a 0 */

  /* Double-loop checking each label against all m->_labels for match */

  for (x = 0; label[x]; x += label[x] + 1) {

    for (y = 0; y < MAX_NUM_LABELS && m->_labels[y]; y++) {

      if (_lmatch(m, label + x, m->_labels[y])) {

        /* Matching label, set up pointer */

        l = label + x;

        short2net((unsigned char *)m->_labels[y] - m->_packet, (unsigned char **)&l);

        label[x] |= '\xc0';

        len = x + 2;

        break;

      }

    }

    if (label[x] & 0xc0)

      break;

  }

  /* Copy into buffer, point there now */

  memcpy(*bufp, label, len);

  l = (char *)*bufp;

  *bufp += len;

  /* For each new_ label, store it's location for future compression */

  for (x = 0; l[x] && m->_label < MAX_NUM_LABELS; x += l[x] + 1) {

    if (l[x] & 0xc0)

      break;

    m->_labels[m->_label++] = l + x;

  }

  return len;

}

static int _rrparse(struct message *m, struct resource *rr, int count, unsigned char **bufp)

{

  int i;

  for (i = 0; i < count; i++) {

    if (_label(m, bufp, &(rr[i].name)))

      return 1;

    rr[i].type     = net2short(bufp);

    rr[i].clazz    = net2short(bufp);

    rr[i].ttl      = net2long(bufp);

    rr[i].rdlength = net2short(bufp);

//    fprintf(stderr, "Record type %d clazz 0x%2x ttl %lu len %d\n", rr[i].type, rr[i].clazz, rr[i].ttl, rr[i].rdlength);

    /* If not going to overflow, make copy of source rdata */

    if (rr[i].rdlength + (*bufp - m->_buf) > MAX_PACKET_LEN || m->_len + rr[i].rdlength > MAX_PACKET_LEN) {

      rr[i].rdlength = 0;

      return 1;

    }

    /* For the following records the rdata will be parsed later. So don't set it here:

     * NS, CNAME, PTR, DNAME, SOA, MX, AFSDB, RT, KX, RP, PX, SRV, NSEC

     * See 18.14 of https://tools.ietf.org/html/rfc6762#page-47 */

    if (rr[i].type == QTYPE_NS || rr[i].type == QTYPE_CNAME || rr[i].type == QTYPE_PTR || rr[i].type == QTYPE_SRV) {

      rr[i].rdlength = 0;

    } else {

      rr[i].rdata = m->_packet + m->_len;

      m->_len += rr[i].rdlength;

      memcpy(rr[i].rdata, *bufp, rr[i].rdlength);

    }

    /* Parse commonly known ones */

    switch (rr[i].type) {

    case QTYPE_A:

      if (m->_len + INET_ADDRSTRLEN > MAX_PACKET_LEN)

        return 1;

      rr[i].known.a.name = (char *)m->_packet + m->_len;

      m->_len += INET_ADDRSTRLEN;

      inet_ntop(AF_INET, *bufp, rr[i].known.a.name, INET_ADDRSTRLEN);

      memcpy(&(rr[i].known.a.ip.s_addr), *bufp, sizeof(rr[i].known.a.ip.s_addr));

      *bufp += sizeof(rr[i].known.a.ip.s_addr);

      break;

    case QTYPE_AAAA:

      if (m->_len + INET6_ADDRSTRLEN > MAX_PACKET_LEN)

        return 1;

      rr[i].known.aaaa.name = (char *)m->_packet + m->_len;

      m->_len += INET6_ADDRSTRLEN;

      inet_ntop(AF_INET6, *bufp, rr[i].known.aaaa.name, INET6_ADDRSTRLEN);

      memcpy(rr[i].known.aaaa.ip6.s6_addr, *bufp, sizeof(rr[i].known.aaaa.ip6.s6_addr));

      *bufp += sizeof(rr[i].known.aaaa.ip6.s6_addr);

      break;

    case QTYPE_NS:

      if (_label(m, bufp, &(rr[i].known.ns.name)))

        return 1;

      break;

    case QTYPE_CNAME:

      if (_label(m, bufp, &(rr[i].known.cname.name)))

        return 1;

      break;

    case QTYPE_PTR:

      if (_label(m, bufp, &(rr[i].known.ptr.name)))

        return 1;

      break;

    case QTYPE_SRV:

      rr[i].known.srv.priority = net2short(bufp);

      rr[i].known.srv.weight = net2short(bufp);

      rr[i].known.srv.port = net2short(bufp);

      if (_label(m, bufp, &(rr[i].known.srv.name)))

        return 1;

      break;

    case QTYPE_TXT:

    default:

      *bufp += rr[i].rdlength;

    }

  }

  return 0;

}

/* Keep all our mem in one (aligned) block for easy freeing */

#define my(x,y)         \

  while (m->_len & 7)     \

    m->_len++;     \

  (x) = (void *)(m->_packet + m->_len); \

  m->_len += (y);

int message_parse(struct message *m, unsigned char *packet)

{

  int i;

  unsigned char *buf;

  if (packet == 0 || m == 0)

    return 1;

  /* Header stuff bit crap */

  m->_buf = buf = packet;

  m->id = net2short(&buf);

  if (buf[0] & 0x80)

    m->header.qr = 1;

  m->header.opcode = (buf[0] & 0x78) >> 3;

  if (buf[0] & 0x04)

    m->header.aa = 1;

  if (buf[0] & 0x02)

    m->header.tc = 1;

  if (buf[0] & 0x01)

    m->header.rd = 1;

  if (buf[1] & 0x80)

    m->header.ra = 1;

  m->header.z = (buf[1] & 0x70) >> 4;

  m->header.rcode = buf[1] & 0x0F;

  buf += 2;

  m->qdcount = net2short(&buf);

  if (m->_len + (sizeof(struct question) * m->qdcount) > MAX_PACKET_LEN - 8) {

    m->qdcount = 0;

    return 1;

  }

  m->ancount = net2short(&buf);

  if (m->_len + (sizeof(struct resource) * m->ancount) > MAX_PACKET_LEN - 8) {

    m->ancount = 0;

    return 1;

  }

  m->nscount = net2short(&buf);

  if (m->_len + (sizeof(struct resource) * m->nscount) > MAX_PACKET_LEN - 8) {

    m->nscount = 0;

    return 1;

  }

  m->arcount = net2short(&buf);

  if (m->_len + (sizeof(struct resource) * m->arcount) > MAX_PACKET_LEN - 8) {

    m->arcount = 0;

    return 1;

  }

  /* Process questions */

  my(m->qd, sizeof(struct question) * m->qdcount);

  for (i = 0; i < m->qdcount; i++) {

    if (_label(m, &buf, &(m->qd[i].name)))

      return 1;

    m->qd[i].type  = net2short(&buf);

    m->qd[i].clazz = net2short(&buf);

  }

  /* Process rrs */

  my(m->an, sizeof(struct resource) * m->ancount);

  my(m->ns, sizeof(struct resource) * m->nscount);

  my(m->ar, sizeof(struct resource) * m->arcount);

  if (_rrparse(m, m->an, m->ancount, &buf))

    return 1;

  if (_rrparse(m, m->ns, m->nscount, &buf))

    return 1;

  if (_rrparse(m, m->ar, m->arcount, &buf))

    return 1;

  return 0;

}

void message_qd(struct message *m, char *name, unsigned short int type, unsigned short int clazz)

{

  m->qdcount++;

  if (m->_buf == 0)

    m->_buf = m->_packet + 12;

  _host(m, &(m->_buf), name);

  short2net(type, &(m->_buf));

  short2net(clazz, &(m->_buf));

}

static void _rrappend(struct message *m, char *name, unsigned short int type, unsigned short int clazz, unsigned long int ttl)

{

  if (m->_buf == 0)

    m->_buf = m->_packet + 12;

  _host(m, &(m->_buf), name);

  short2net(type, &(m->_buf));

  short2net(clazz, &(m->_buf));

  long2net(ttl, &(m->_buf));

}

void message_an(struct message *m, char *name, unsigned short int type, unsigned short int clazz, unsigned long int ttl)

{

  m->ancount++;

  _rrappend(m, name, type, clazz, ttl);

}

void message_ns(struct message *m, char *name, unsigned short int type, unsigned short int clazz, unsigned long int ttl)

{

  m->nscount++;

  _rrappend(m, name, type, clazz, ttl);

}

void message_ar(struct message *m, char *name, unsigned short int type, unsigned short int clazz, unsigned long int ttl)

{

  m->arcount++;

  _rrappend(m, name, type, clazz, ttl);

}

void message_rdata_long(struct message *m, unsigned long l)

{

  short2net(4, &(m->_buf));

  long2net(l, &(m->_buf));

}

void message_rdata_ipv4(struct message *m, struct in_addr a)

{

  short2net(4, &(m->_buf));

  memcpy(m->_buf, &a.s_addr, 4);

  m->_buf += 4;

}

void message_rdata_ipv6(struct message *m, struct in6_addr a6)

{

  short2net(16, &(m->_buf));

  memcpy(m->_buf, a6.s6_addr, 16);

  m->_buf += 16;

}

void message_rdata_name(struct message *m, char *name)

{

  unsigned char *mybuf = m->_buf;

  m->_buf += 2;

  short2net(_host(m, &(m->_buf), name), &mybuf);

}

void message_rdata_srv(struct message *m, unsigned short int priority, unsigned short int weight, unsigned short int port, char *name)

{

  unsigned char *mybuf = m->_buf;

  m->_buf += 2;

  short2net(priority, &(m->_buf));

  short2net(weight, &(m->_buf));

  short2net(port, &(m->_buf));

  short2net(_host(m, &(m->_buf), name) + 6, &mybuf);

}

void message_rdata_raw(struct message *m, unsigned char *rdata, unsigned short int rdlength)

{

  if ((m->_buf - m->_packet) + rdlength > 4096)

    rdlength = 0;

  short2net(rdlength, &(m->_buf));

  memcpy(m->_buf, rdata, rdlength);

  m->_buf += rdlength;

}

unsigned char *message_packet(struct message *m)

{

  unsigned char c, *buf = m->_buf;

  m->_buf = m->_packet;

  short2net(m->id, &(m->_buf));

  if (m->header.qr)

    m->_buf[0] |= 0x80;

  if ((c = m->header.opcode))

    m->_buf[0] |= (c << 3);

  if (m->header.aa)

    m->_buf[0] |= 0x04;

  if (m->header.tc)

    m->_buf[0] |= 0x02;

  if (m->header.rd)

    m->_buf[0] |= 0x01;

  if (m->header.ra)

    m->_buf[1] |= 0x80;

  if ((c = m->header.z))

    m->_buf[1] |= (c << 4);

  if (m->header.rcode)

    m->_buf[1] |= m->header.rcode;

  m->_buf += 2;

  short2net(m->qdcount, &(m->_buf));

  short2net(m->ancount, &(m->_buf));

  short2net(m->nscount, &(m->_buf));

  short2net(m->arcount, &(m->_buf));

  m->_buf = buf;    /* Restore, so packet_len works */

  return m->_packet;

}

int message_packet_len(struct message *m)

{

  if (m->_buf == 0)

    return 12;

  return (int)(m->_buf - m->_packet);

}