stunmessage.c 15.6 KB
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/*
 * This file is part of the Nice GLib ICE library.
 *
 * (C) 2007 Nokia Corporation. All rights reserved.
 *  Contact: Rémi Denis-Courmont
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is the Nice GLib ICE library.
 *
 * The Initial Developers of the Original Code are Collabora Ltd and Nokia
 * Corporation. All Rights Reserved.
 *
 * Contributors:
 *   Rémi Denis-Courmont, Nokia
 *
 * Alternatively, the contents of this file may be used under the terms of the
 * the GNU Lesser General Public License Version 2.1 (the "LGPL"), in which
 * case the provisions of LGPL are applicable instead of those above. If you
 * wish to allow use of your version of this file only under the terms of the
 * LGPL and not to allow others to use your version of this file under the
 * MPL, indicate your decision by deleting the provisions above and replace
 * them with the notice and other provisions required by the LGPL. If you do
 * not delete the provisions above, a recipient may use your version of this
 * file under either the MPL or the LGPL.
 */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

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#include "stunmessage.h"

#ifdef _WIN32
#include <winsock2.h>
#else
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#include <sys/types.h>
#include <sys/socket.h>
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#endif
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#include <string.h>
#include <stdlib.h>



bool stun_message_init (StunMessage *msg, stun_class_t c, stun_method_t m,
    const stun_transid_t id)
{

  if (msg->buffer_len < STUN_MESSAGE_HEADER_LENGTH)
    return FALSE;

  memset (msg->buffer, 0, 4);
  stun_set_type (msg->buffer, c, m);

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  memcpy (msg->buffer + STUN_MESSAGE_TRANS_ID_POS,
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      id, STUN_MESSAGE_TRANS_ID_LEN);
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  return TRUE;
}

uint16_t stun_message_length (const StunMessage *msg)
{
  return stun_getw (msg->buffer + STUN_MESSAGE_LENGTH_POS) +
      STUN_MESSAGE_HEADER_LENGTH;
}




const void *
stun_message_find (const StunMessage *msg, stun_attr_type_t type,
    uint16_t *restrict palen)
{
  size_t length = stun_message_length (msg);
  size_t offset = 0;


  offset = STUN_MESSAGE_ATTRIBUTES_POS;

  while (offset < length)
  {
    uint16_t atype = stun_getw (msg->buffer + offset);
    size_t alen = stun_getw (msg->buffer + offset + STUN_ATTRIBUTE_TYPE_LEN);


    offset += STUN_ATTRIBUTE_VALUE_POS;

    if (atype == type)
    {
      *palen = alen;
      return msg->buffer + offset;
    }

    /* Look for and ignore misordered attributes */
    switch (atype)
    {
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      case STUN_ATTRIBUTE_MESSAGE_INTEGRITY:
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        /* Only fingerprint may come after M-I */
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        if (type == STUN_ATTRIBUTE_FINGERPRINT)
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          break;

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      case STUN_ATTRIBUTE_FINGERPRINT:
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        /* Nothing may come after FPR */
        return NULL;
    }

    alen = stun_align (alen);
    offset += alen;
  }

  return NULL;
}


int stun_message_find_flag (const StunMessage *msg, stun_attr_type_t type)
{
  const void *ptr;
  uint16_t len;

  ptr = stun_message_find (msg, type, &len);
  if (ptr == NULL)
    return ENOENT;
  return (len == 0) ? 0 : EINVAL;
}


int
stun_message_find32 (const StunMessage *msg, stun_attr_type_t type,
    uint32_t *restrict pval)
{
  const void *ptr;
  uint16_t len;

  ptr = stun_message_find (msg, type, &len);
  if (ptr == NULL)
    return ENOENT;

  if (len == 4)
  {
    uint32_t val;

    memcpy (&val, ptr, sizeof (val));
    *pval = ntohl (val);
    return 0;
  }
  return EINVAL;
}


int stun_message_find64 (const StunMessage *msg, stun_attr_type_t type,
    uint64_t *pval)
{
  const void *ptr;
  uint16_t len;

  ptr = stun_message_find (msg, type, &len);
  if (ptr == NULL)
    return ENOENT;

  if (len == 8)
  {
    uint32_t tab[2];

    memcpy (tab, ptr, sizeof (tab));
    *pval = ((uint64_t)ntohl (tab[0]) << 32) | ntohl (tab[1]);
    return 0;
  }
  return EINVAL;
}


int stun_message_find_string (const StunMessage *msg, stun_attr_type_t type,
    char *buf, size_t buflen)
{
  const unsigned char *ptr;
  uint16_t len;

  ptr = stun_message_find (msg, type, &len);
  if (ptr == NULL)
    return ENOENT;

  if (len >= buflen)
    return ENOBUFS;

  memcpy (buf, ptr, len);
  buf[len] = '\0';
  return 0;
}


int
stun_message_find_addr (const StunMessage *msg, stun_attr_type_t type,
    struct sockaddr *restrict addr, socklen_t *restrict addrlen)
{
  const uint8_t *ptr;
  uint16_t len;

  ptr = stun_message_find (msg, type, &len);
  if (ptr == NULL)
    return ENOENT;

  if (len < 4)
    return EINVAL;

  switch (ptr[1])
  {
    case 1:
      {
        struct sockaddr_in *ip4 = (struct sockaddr_in *)addr;
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        if (((size_t) *addrlen < sizeof (*ip4)) || (len != 8))
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        {
          *addrlen = sizeof (*ip4);
          return EINVAL;
        }

        memset (ip4, 0, *addrlen);
        ip4->sin_family = AF_INET;
#ifdef HAVE_SA_LEN
        ip4->sin_len =
#endif
            *addrlen = sizeof (*ip4);
        memcpy (&ip4->sin_port, ptr + 2, 2);
        memcpy (&ip4->sin_addr, ptr + 4, 4);
        return 0;
      }

    case 2:
      {
        struct sockaddr_in6 *ip6 = (struct sockaddr_in6 *)addr;
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        if (((size_t) *addrlen < sizeof (*ip6)) || (len != 20))
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        {
          *addrlen = sizeof (*ip6);
          return EINVAL;
        }

        memset (ip6, 0, *addrlen);
        ip6->sin6_family = AF_INET6;
#ifdef HAVE_SA_LEN
        ip6->sin6_len =
#endif
            *addrlen = sizeof (*ip6);
        memcpy (&ip6->sin6_port, ptr + 2, 2);
        memcpy (&ip6->sin6_addr, ptr + 4, 16);
        return 0;
      }
  }

  return EAFNOSUPPORT;
}

int
stun_message_find_xor_addr (const StunMessage *msg, stun_attr_type_t type,
    struct sockaddr *restrict addr,
    socklen_t *restrict addrlen)
{
  int val = stun_message_find_addr (msg, type, addr, addrlen);
  if (val)
    return val;

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  return stun_xor_address (msg, addr, *addrlen, STUN_MAGIC_COOKIE);
}

int
stun_message_find_xor_addr_full (const StunMessage *msg, stun_attr_type_t type,
    struct sockaddr *restrict addr,  socklen_t *restrict addrlen,
    uint32_t magic_cookie)
{
  int val = stun_message_find_addr (msg, type, addr, addrlen);
  if (val)
    return val;

  return stun_xor_address (msg, addr, *addrlen, magic_cookie);
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}

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int stun_message_find_error (const StunMessage *msg, int *restrict code)
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{
  uint16_t alen;
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  const uint8_t *ptr = stun_message_find (msg, STUN_ATTRIBUTE_ERROR_CODE, &alen);
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  uint8_t class, number;

  if (ptr == NULL)
    return ENOENT;
  if (alen < 4)
    return EINVAL;

  class = ptr[2] & 0x7;
  number = ptr[3];
  if ((class < 3) || (class > 6) || (number > 99))
    return EINVAL;

  *code = (class * 100) + number;
  return 0;
}

/**
 * Reserves room for appending an attribute to an unfinished STUN message.
 * @param msg STUN message buffer
 * @param msize STUN message buffer size
 * @param type message type (host byte order)
 * @param length attribute payload byte length
 * @return a pointer to an unitialized buffer of <length> bytes to
 * where the attribute payload must be written, or NULL if there is not
 * enough room in the STUN message buffer. Return value is always on a
 * 32-bits boundary.
 */
void *
stun_message_append (StunMessage *msg, stun_attr_type_t type, size_t length)
{
  uint8_t *a;
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  uint16_t mlen = stun_message_length (msg);
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  if ((size_t)mlen + STUN_ATTRIBUTE_HEADER_LENGTH + length > msg->buffer_len)
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    return NULL;


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  a = msg->buffer + mlen;
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  a = stun_setw (a, type);
  /* NOTE: If cookie is not present, we need to force the attribute length
   * to a multiple of 4 for compatibility with old RFC3489 */
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  a = stun_setw (a, stun_has_cookie (msg) ? length : stun_align (length));
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  mlen +=  4 + length;
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  /* Add padding if needed */
  memset (a + length, ' ', stun_padding (length));
  mlen += stun_padding (length);

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  stun_setw (msg->buffer + STUN_MESSAGE_LENGTH_POS, mlen - STUN_MESSAGE_HEADER_LENGTH);
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  return a;
}


/**
 * Appends an attribute from memory.
 * @param msg STUN message buffer
 * @param msize STUN message buffer size
 * @param type attribute type (host byte order)
 * @param data memory address to copy payload from
 * @param len attribute payload length
 * @return 0 on success, ENOBUFS on error.
 */
int
stun_message_append_bytes (StunMessage *msg, stun_attr_type_t type,
    const void *data, size_t len)
{
  void *ptr = stun_message_append (msg, type, len);
  if (ptr == NULL)
    return ENOBUFS;

  memcpy (ptr, data, len);
  return 0;
}


int stun_message_append_flag (StunMessage *msg, stun_attr_type_t type)
{
  return stun_message_append_bytes (msg, type, NULL, 0);
}


int
stun_message_append32 (StunMessage *msg, stun_attr_type_t type,
    uint32_t value)
{
  value = htonl (value);
  return stun_message_append_bytes (msg, type, &value, 4);
}


int stun_message_append64 (StunMessage *msg, stun_attr_type_t type,
    uint64_t value)
{
  uint32_t tab[2];
  tab[0] = htonl ((uint32_t)(value >> 32));
  tab[1] = htonl ((uint32_t)value);
  return stun_message_append_bytes (msg, type, tab, 8);
}


int
stun_message_append_string (StunMessage * msg, stun_attr_type_t type,
    const char *str)
{
  return stun_message_append_bytes (msg, type, str, strlen (str));
}

int
stun_message_append_addr (StunMessage *msg, stun_attr_type_t type,
    const struct sockaddr *restrict addr, socklen_t addrlen)
{
  const void *pa;
  uint8_t *ptr;
  uint16_t alen, port;
  uint8_t family;

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  if ((size_t) addrlen < sizeof (struct sockaddr))
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    return EINVAL;

  switch (addr->sa_family)
  {
    case AF_INET:
      {
        const struct sockaddr_in *ip4 = (const struct sockaddr_in *)addr;
        family = 1;
        port = ip4->sin_port;
        alen = 4;
        pa = &ip4->sin_addr;
        break;
      }

    case AF_INET6:
      {
        const struct sockaddr_in6 *ip6 = (const struct sockaddr_in6 *)addr;
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        if ((size_t) addrlen < sizeof (*ip6))
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          return EINVAL;

        family = 2;
        port = ip6->sin6_port;
        alen = 16;
        pa = &ip6->sin6_addr;
        break;
      }

    default:
      return EAFNOSUPPORT;
  }

  ptr = stun_message_append (msg, type, 4 + alen);
  if (ptr == NULL)
    return ENOBUFS;

  ptr[0] = 0;
  ptr[1] = family;
  memcpy (ptr + 2, &port, 2);
  memcpy (ptr + 4, pa, alen);
  return 0;
}


int stun_message_append_xor_addr (StunMessage *msg, stun_attr_type_t type,
    const struct sockaddr *restrict addr, socklen_t addrlen)
{
  int val;
  /* Must be big enough to hold any supported address: */
  struct sockaddr_storage xor;

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  if ((size_t) addrlen > sizeof (xor))
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    addrlen = sizeof (xor);
  memcpy (&xor, addr, addrlen);

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  val = stun_xor_address (msg, (struct sockaddr *)&xor, addrlen,
      STUN_MAGIC_COOKIE);
  if (val)
    return val;

  return stun_message_append_addr (msg, type, (struct sockaddr *)&xor,
      addrlen);
}

int stun_message_append_xor_addr_full (StunMessage *msg, stun_attr_type_t type,
    const struct sockaddr *restrict addr, socklen_t addrlen,
    uint32_t magic_cookie)
{
  int val;
  /* Must be big enough to hold any supported address: */
  struct sockaddr_storage xor;

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  if ((size_t) addrlen > sizeof (xor))
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    addrlen = sizeof (xor);
  memcpy (&xor, addr, addrlen);

  val = stun_xor_address (msg, (struct sockaddr *)&xor, addrlen, magic_cookie);
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  if (val)
    return val;

  return stun_message_append_addr (msg, type, (struct sockaddr *)&xor,
      addrlen);
}



/**
 * Appends an ERROR-CODE attribute.
 * @param msg STUN message buffer
 * @param msize STUN message buffer size
 * @param code STUN host-byte order integer error code
 * @return 0 on success, or ENOBUFS otherwise
 */
int
stun_message_append_error (StunMessage *msg, stun_error_t code)
{
  const char *str = stun_strerror (code);
  size_t len = strlen (str);
  div_t d = div (code, 100);

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  uint8_t *ptr = stun_message_append (msg, STUN_ATTRIBUTE_ERROR_CODE, 4 + len);
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  if (ptr == NULL)
    return ENOBUFS;

  memset (ptr, 0, 2);
  ptr[2] = d.quot;
  ptr[3] = d.rem;
  memcpy (ptr + 4, str, len);
  return 0;
}

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int stun_message_validate_buffer_length (const uint8_t *msg, size_t length)
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{
  size_t mlen;
  size_t len;

  if (length < 1)
  {
    stun_debug ("STUN error: No data!\n");
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    return STUN_MESSAGE_BUFFER_INVALID;
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  }

  if (msg[0] >> 6)
  {
    stun_debug ("STUN error: RTP or other non-protocol packet!\n");
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    return STUN_MESSAGE_BUFFER_INVALID; // RTP or other non-STUN packet
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  }

  if (length < 4)
  {
    stun_debug ("STUN error: Incomplete STUN message header!\n");
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    return STUN_MESSAGE_BUFFER_INCOMPLETE;
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  }

  mlen = stun_getw (msg + STUN_MESSAGE_LENGTH_POS) +
      STUN_MESSAGE_HEADER_LENGTH;

  if (stun_padding (mlen))
  {
    stun_debug ("STUN error: Invalid message length: %u!\n", (unsigned)mlen);
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    return STUN_MESSAGE_BUFFER_INVALID; // wrong padding
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  }

  if (length < mlen)
  {
    stun_debug ("STUN error: Incomplete message: %u of %u bytes!\n",
        (unsigned)length, (unsigned)mlen);
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    return STUN_MESSAGE_BUFFER_INCOMPLETE; // partial message
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  }

  msg += 20;
  len = mlen - 20;

  /* from then on, we know we have the entire packet in buffer */
  while (len > 0)
  {
    size_t alen = stun_align (stun_getw (msg + STUN_ATTRIBUTE_TYPE_LEN));

    /* thanks to padding check, if (end > msg) then there is not only one
     * but at least 4 bytes left */
    len -= 4;

    if (len < alen)
    {
      stun_debug ("STUN error: %u instead of %u bytes for attribute!\n",
          (unsigned)len, (unsigned)alen);
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      return STUN_MESSAGE_BUFFER_INVALID; // no room for attribute value + padding
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    }

    len -= alen;
    msg += 4 + alen;
  }

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  return mlen;
}

/**
 * copies STUN message transaction ID
 */
void stun_message_id (const StunMessage *msg, stun_transid_t id)
{
  memcpy (id, msg->buffer + STUN_MESSAGE_TRANS_ID_POS, STUN_MESSAGE_TRANS_ID_LEN);
}

/**
 * @return STUN message method (value from 0 to 0xfff)
 */
stun_method_t stun_message_get_method (const StunMessage *msg)
{
  uint16_t t = stun_getw (msg->buffer);
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  /* HACK HACK HACK
     A google/msn data indication is 0x0115 which is contrary to the rfc3489bis
     which states that 8th and 12th bits are for the class and that 0x01 is
     for indications...
     So 0x0115 is reported as a "connect error response", while it should be
     a data indication, which message type should actually be 0x0017
     This should fix the issue, and it's considered safe since the "connect"
     method doesn't exist anymore */
  if (t == 0x0115)
    t = 0x0017;
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  return (stun_method_t)(((t & 0x3e00) >> 2) | ((t & 0x00e0) >> 1) |
                          (t & 0x000f));
}


/**
 * @return STUN message class in host byte order (value from 0 to 3)
 */
stun_class_t stun_message_get_class (const StunMessage *msg)
{
  uint16_t t = stun_getw (msg->buffer);
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  /* HACK HACK HACK
     A google/msn data indication is 0x0115 which is contrary to the rfc3489bis
     which states that 8th and 12th bits are for the class and that 0x01 is
     for indications...
     So 0x0115 is reported as a "connect error response", while it should be
     a data indication, which message type should actually be 0x0017
     This should fix the issue, and it's considered safe since the "connect"
     method doesn't exist anymore */
  if (t == 0x0115)
    t = 0x0017;
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  return (stun_class_t)(((t & 0x0100) >> 7) | ((t & 0x0010) >> 4));
}

/**
 * Checks if an attribute is present within a STUN message.
 *
 * @param msg valid STUN message
 * @param type STUN attribute type (host byte order)
 *
 * @return whether there is a MESSAGE-INTEGRITY attribute
 */
bool stun_message_has_attribute (const StunMessage *msg, stun_attr_type_t type)
{
  uint16_t dummy;
  return stun_message_find (msg, type, &dummy) != NULL;
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}