/src/freeradius-server/src/protocols/radius/base.c

Source
/*
 *   This library is free software; you can redistribute it and/or
 *   modify it under the terms of the GNU Lesser General Public
 *   License as published by the Free Software Foundation; either
 *   version 2.1 of the License, or (at your option) any later version.
 *
 *   This library is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 *   Lesser General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public
 *   License along with this library; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */

/**
 * $Id: 67362bd5b8ce28d82d833f91f081c0f39b634983 $
 *
 * @file protocols/radius/base.c
 * @brief Functions to send/receive radius packets.
 *
 * @copyright 2000-2003,2006 The FreeRADIUS server project
 */
RCSID("$Id: 67362bd5b8ce28d82d833f91f081c0f39b634983 $")

#include <fcntl.h>
#include <ctype.h>

#include "attrs.h"
#include "radius.h"

#include <freeradius-devel/io/pair.h>
#include <freeradius-devel/util/md5.h>
#include <freeradius-devel/util/net.h>
#include <freeradius-devel/util/proto.h>
#include <freeradius-devel/util/udp.h>
#include <freeradius-devel/protocol/radius/freeradius.internal.h>

static uint32_t instance_count = 0;
static bool instantiated = false;

fr_dict_t const *dict_freeradius;
fr_dict_t const *dict_radius;

extern fr_dict_autoload_t libfreeradius_radius_dict[];
fr_dict_autoload_t libfreeradius_radius_dict[] = {
  { .out = &dict_freeradius, .proto = "freeradius" },
  { .out = &dict_radius, .proto = "radius" },

  DICT_AUTOLOAD_TERMINATOR
};

fr_dict_attr_t const *attr_packet_type;
fr_dict_attr_t const *attr_packet_authentication_vector;
fr_dict_attr_t const *attr_chap_challenge;
fr_dict_attr_t const *attr_chargeable_user_identity;
fr_dict_attr_t const *attr_eap_message;
fr_dict_attr_t const *attr_message_authenticator;
fr_dict_attr_t const *attr_state;
fr_dict_attr_t const *attr_vendor_specific;
fr_dict_attr_t const *attr_nas_filter_rule;

extern fr_dict_attr_autoload_t libfreeradius_radius_dict_attr[];
fr_dict_attr_autoload_t libfreeradius_radius_dict_attr[] = {
  { .out = &attr_packet_type, .name = "Packet-Type", .type = FR_TYPE_UINT32, .dict = &dict_radius },
  { .out = &attr_packet_authentication_vector, .name = "Packet-Authentication-Vector", .type = FR_TYPE_OCTETS, .dict = &dict_radius },
  { .out = &attr_chap_challenge, .name = "CHAP-Challenge", .type = FR_TYPE_OCTETS, .dict = &dict_radius },
  { .out = &attr_chargeable_user_identity, .name = "Chargeable-User-Identity", .type = FR_TYPE_OCTETS, .dict = &dict_radius },

  { .out = &attr_eap_message, .name = "EAP-Message", .type = FR_TYPE_OCTETS, .dict = &dict_radius },
  { .out = &attr_message_authenticator, .name = "Message-Authenticator", .type = FR_TYPE_OCTETS, .dict = &dict_radius },
  { .out = &attr_state, .name = "State", .type = FR_TYPE_OCTETS, .dict = &dict_radius },
  { .out = &attr_vendor_specific, .name = "Vendor-Specific", .type = FR_TYPE_VSA, .dict = &dict_radius },
  { .out = &attr_nas_filter_rule, .name = "NAS-Filter-Rule", .type = FR_TYPE_STRING, .dict = &dict_radius },

  DICT_AUTOLOAD_TERMINATOR
};

/*
 *  Some messages get printed out only in debugging mode.
 */
#define FR_DEBUG_STRERROR_PRINTF    if (fr_debug_lvl) fr_strerror_printf
#define FR_DEBUG_STRERROR_PRINTF_PUSH   if (fr_debug_lvl) fr_strerror_printf_push

fr_table_num_sorted_t const fr_radius_require_ma_table[] = {
  { L("auto"),    FR_RADIUS_REQUIRE_MA_AUTO   },
  { L("false"),   FR_RADIUS_REQUIRE_MA_NO     },
  { L("no"),    FR_RADIUS_REQUIRE_MA_NO     },
  { L("true"),    FR_RADIUS_REQUIRE_MA_YES    },
  { L("yes"),   FR_RADIUS_REQUIRE_MA_YES    },
};
size_t fr_radius_require_ma_table_len = NUM_ELEMENTS(fr_radius_require_ma_table);

fr_table_num_sorted_t const fr_radius_limit_proxy_state_table[] = {
  { L("auto"),    FR_RADIUS_LIMIT_PROXY_STATE_AUTO  },
  { L("false"),   FR_RADIUS_LIMIT_PROXY_STATE_NO    },
  { L("no"),    FR_RADIUS_LIMIT_PROXY_STATE_NO    },
  { L("true"),    FR_RADIUS_LIMIT_PROXY_STATE_YES   },
  { L("yes"),   FR_RADIUS_LIMIT_PROXY_STATE_YES   },
};
size_t fr_radius_limit_proxy_state_table_len = NUM_ELEMENTS(fr_radius_limit_proxy_state_table);

fr_table_num_sorted_t const fr_radius_request_name_table[] = {
  { L("acct"),    FR_RADIUS_CODE_ACCOUNTING_REQUEST },
  { L("auth"),    FR_RADIUS_CODE_ACCESS_REQUEST   },
  { L("auto"),    FR_RADIUS_CODE_UNDEFINED    },
  { L("challenge"), FR_RADIUS_CODE_ACCESS_CHALLENGE   },
  { L("coa"),   FR_RADIUS_CODE_COA_REQUEST    },
  { L("disconnect"),  FR_RADIUS_CODE_DISCONNECT_REQUEST },
  { L("status"),    FR_RADIUS_CODE_STATUS_SERVER    }
};
size_t fr_radius_request_name_table_len = NUM_ELEMENTS(fr_radius_request_name_table);

char const *fr_radius_packet_name[FR_RADIUS_CODE_MAX] = {
  "",         //!< 0
  "Access-Request",
  "Access-Accept",
  "Access-Reject",
  "Accounting-Request",
  "Accounting-Response",
  "Accounting-Status",
  "Password-Request",
  "Password-Accept",
  "Password-Reject",
  "Accounting-Message",     //!< 10
  "Access-Challenge",
  "Status-Server",
  "Status-Client",
  "14",
  "15",
  "16",
  "17",
  "18",
  "19",
  "20",         //!< 20
  "Resource-Free-Request",
  "Resource-Free-Response",
  "Resource-Query-Request",
  "Resource-Query-Response",
  "Alternate-Resource-Reclaim-Request",
  "NAS-Reboot-Request",
  "NAS-Reboot-Response",
  "28",
  "Next-Passcode",
  "New-Pin",        //!< 30
  "Terminate-Session",
  "Password-Expired",
  "Event-Request",
  "Event-Response",
  "35",
  "36",
  "37",
  "38",
  "39",
  "Disconnect-Request",     //!< 40
  "Disconnect-ACK",
  "Disconnect-NAK",
  "CoA-Request",
  "CoA-ACK",
  "CoA-NAK",
  "46",
  "47",
  "48",
  "49",
  "IP-Address-Allocate",      //!< 50
  "IP-Address-Release",
  "Protocol-Error",
};


/** If we get a reply, the request must come from one of a small
 * number of packet types.
 */
const fr_radius_packet_code_t allowed_replies[FR_RADIUS_CODE_MAX] = {
  [FR_RADIUS_CODE_ACCESS_ACCEPT]    = FR_RADIUS_CODE_ACCESS_REQUEST,
  [FR_RADIUS_CODE_ACCESS_CHALLENGE] = FR_RADIUS_CODE_ACCESS_REQUEST,
  [FR_RADIUS_CODE_ACCESS_REJECT]    = FR_RADIUS_CODE_ACCESS_REQUEST,

  [FR_RADIUS_CODE_ACCOUNTING_RESPONSE]  = FR_RADIUS_CODE_ACCOUNTING_REQUEST,

  [FR_RADIUS_CODE_COA_ACK]    = FR_RADIUS_CODE_COA_REQUEST,
  [FR_RADIUS_CODE_COA_NAK]    = FR_RADIUS_CODE_COA_REQUEST,

  [FR_RADIUS_CODE_DISCONNECT_ACK]   = FR_RADIUS_CODE_DISCONNECT_REQUEST,
  [FR_RADIUS_CODE_DISCONNECT_NAK]   = FR_RADIUS_CODE_DISCONNECT_REQUEST,

  [FR_RADIUS_CODE_PROTOCOL_ERROR]   = FR_RADIUS_CODE_PROTOCOL_ERROR,  /* Any */
};

FR_DICT_ATTR_FLAG_FUNC(fr_radius_attr_flags_t, abinary)
FR_DICT_ATTR_FLAG_FUNC(fr_radius_attr_flags_t, concat)

static int dict_flag_encrypt(fr_dict_attr_t **da_p, char const *value, UNUSED fr_dict_flag_parser_rule_t const *rules)
{
  static fr_table_num_sorted_t const encrypted[] = {
    { L("Ascend-Secret"),  RADIUS_FLAG_ENCRYPT_ASCEND_SECRET },
    { L("Tunnel-Password"),  RADIUS_FLAG_ENCRYPT_TUNNEL_PASSWORD },
    { L("User-Password"),  RADIUS_FLAG_ENCRYPT_USER_PASSWORD}
  };
  static size_t encrypted_len = NUM_ELEMENTS(encrypted);

  fr_radius_attr_flags_encrypt_t encrypt;
  fr_radius_attr_flags_t *flags = fr_dict_attr_ext(*da_p, FR_DICT_ATTR_EXT_PROTOCOL_SPECIFIC);

  encrypt = fr_table_value_by_str(encrypted, value, RADIUS_FLAG_ENCRYPT_INVALID);
  if (encrypt == RADIUS_FLAG_ENCRYPT_INVALID) {
    fr_strerror_printf("Unknown encryption type '%s'", value);
    return -1;
  }

  flags->encrypt = encrypt;

  return 0;
}

FR_DICT_ATTR_FLAG_FUNC(fr_radius_attr_flags_t, extended)
FR_DICT_ATTR_FLAG_FUNC(fr_radius_attr_flags_t, has_tag)
FR_DICT_ATTR_FLAG_FUNC(fr_radius_attr_flags_t, long_extended)

static fr_dict_flag_parser_t const radius_flags[] = {
  { L("abinary"),     { .func = dict_flag_abinary } },
  { L("concat"),      { .func = dict_flag_concat } },
  { L("encrypt"),     { .func = dict_flag_encrypt, .needs_value = true } },
  { L("extended"),    { .func = dict_flag_extended } },
  { L("has_tag"),     { .func = dict_flag_has_tag } },
  { L("long_extended"),   { .func = dict_flag_long_extended } }
};

int fr_radius_allow_reply(int code, bool allowed[static FR_RADIUS_CODE_MAX])
{
  int i;

  if ((code <= 0) || (code >= FR_RADIUS_CODE_MAX)) return -1;

  for (i = 1; i < FR_RADIUS_CODE_MAX; i++) {
    allowed[i] |= (allowed_replies[i] == (fr_radius_packet_code_t) code);
  }

  return 0;
}

/**  Do Ascend-Send / Recv-Secret calculation.
 *
 * The secret is hidden by xoring with a MD5 digest created from
 * the RADIUS shared secret and the authentication vector.
 * We put them into MD5 in the reverse order from that used when
 * encrypting passwords to RADIUS.
 */
ssize_t fr_radius_ascend_secret(fr_dbuff_t *dbuff, uint8_t const *in, size_t inlen,
        char const *secret, size_t secret_len, uint8_t const *vector)
{
  fr_md5_ctx_t    *md5_ctx;
  size_t      i;
  uint8_t     digest[MD5_DIGEST_LENGTH];
  fr_dbuff_t    work_dbuff = FR_DBUFF(dbuff);

  FR_DBUFF_EXTEND_LOWAT_OR_RETURN(&work_dbuff, sizeof(digest));

  md5_ctx = fr_md5_ctx_alloc_from_list();
  fr_md5_update(md5_ctx, vector, RADIUS_AUTH_VECTOR_LENGTH);
  fr_md5_update(md5_ctx, (uint8_t const *) secret, secret_len);
  fr_md5_final(digest, md5_ctx);
  fr_md5_ctx_free_from_list(&md5_ctx);

  if (inlen > sizeof(digest)) inlen = sizeof(digest);
  for (i = 0; i < inlen; i++) digest[i] ^= in[i];

  fr_dbuff_in_memcpy(&work_dbuff, digest, sizeof(digest));

  return fr_dbuff_set(dbuff, &work_dbuff);
}

/** Basic validation of RADIUS packet header
 *
 * @note fr_strerror errors are only available if fr_debug_lvl > 0. This is to reduce CPU time
 *  consumed when discarding malformed packet.
 *
 * @param[in] sockfd we're reading from.
 * @param[out] src_ipaddr of the packet.
 * @param[out] src_port of the packet.
 * @param[out] code Pointer to where to write the packet code.
 * @return
 *  - -1 on failure.
 *  - 1 on decode error.
 *  - >= RADIUS_HEADER_LENGTH on success. This is the packet length as specified in the header.
 */
ssize_t fr_radius_recv_header(int sockfd, fr_ipaddr_t *src_ipaddr, uint16_t *src_port, unsigned int *code)
{
  ssize_t     data_len, packet_len;
  uint8_t     header[4];

  data_len = udp_recv_peek(sockfd, header, sizeof(header), UDP_FLAGS_PEEK, src_ipaddr, src_port);
  if (data_len < 0) {
    if ((errno == EAGAIN) || (errno == EINTR)) return 0;
    return -1;
  }

  /*
   *  Too little data is available, discard the packet.
   */
  if (data_len < 4) {
    char buffer[INET6_ADDRSTRLEN];

    FR_DEBUG_STRERROR_PRINTF("Expected at least 4 bytes of header data, got %zd bytes", data_len);
invalid:
    FR_DEBUG_STRERROR_PRINTF_PUSH("Invalid data from %s",
                inet_ntop(src_ipaddr->af, &src_ipaddr->addr, buffer, sizeof(buffer)));
    (void) udp_recv_discard(sockfd);

    return 0;
  }

  /*
   *  See how long the packet says it is.
   */
  packet_len = (header[2] * 256) + header[3];

  /*
   *  The length in the packet says it's less than
   *  a RADIUS header length: discard it.
   */
  if (packet_len < RADIUS_HEADER_LENGTH) {
    FR_DEBUG_STRERROR_PRINTF("Expected at least " STRINGIFY(RADIUS_HEADER_LENGTH)  " bytes of packet "
           "data, got %zd bytes", packet_len);
    goto invalid;
  }

  /*
   *  Enforce RFC requirements, for sanity.
   *  Anything after 4k will be discarded.
   */
  if (packet_len > MAX_PACKET_LEN) {
    FR_DEBUG_STRERROR_PRINTF("Length field value too large, expected maximum of "
           STRINGIFY(MAX_PACKET_LEN) " bytes, got %zd bytes", packet_len);
    goto invalid;
  }

  *code = header[0];

  /*
   *  The packet says it's this long, but the actual UDP
   *  size could still be smaller.
   */
  return packet_len;
}

/** Sign a previously encoded packet
 *
 * Calculates the request/response authenticator for packets which need it, and fills
 * in the message-authenticator value if the attribute is present in the encoded packet.
 *
 * @param[in,out] packet  (request or response).
 * @param[in] vector    original packet vector to use
 * @param[in] secret    to sign the packet with.
 * @param[in] secret_len  The length of the secret.
 * @return
 *  - <0 on error
 *  - 0 on success
 */
int fr_radius_sign(uint8_t *packet, uint8_t const *vector,
       uint8_t const *secret, size_t secret_len)
{
  uint8_t   *msg, *end;
  size_t    packet_len = fr_nbo_to_uint16(packet + 2);

  /*
   *  No real limit on secret length, this is just
   *  to catch uninitialised fields.
   */
  if (!fr_cond_assert(secret_len <= UINT16_MAX)) {
    fr_strerror_printf("Secret is too long.  Expected <= %u, got %zu",
           (unsigned int) UINT16_MAX, secret_len);
    return -1;
  }

  if (packet_len < RADIUS_HEADER_LENGTH) {
    fr_strerror_const("Packet must be encoded before calling fr_radius_sign()");
    return -1;
  }

  /*
   *  Find Message-Authenticator.  Its value has to be
   *  calculated before we calculate the Request
   *  Authenticator or the Response Authenticator.
   */
  msg = packet + RADIUS_HEADER_LENGTH;
  end = packet + packet_len;

  while (msg < end) {
    if ((end - msg) < 2) goto invalid_attribute;

    if (msg[0] != FR_MESSAGE_AUTHENTICATOR) {
      if (msg[1] < 2) goto invalid_attribute;

      if ((msg + msg[1]) > end) {
      invalid_attribute:
        fr_strerror_printf("Invalid attribute at offset %zd", msg - packet);
        return -1;
      }
      msg += msg[1];
      continue;
    }

    if (msg[1] < 18) {
      fr_strerror_const("Message-Authenticator is too small");
      return -1;
    }

    switch (packet[0]) {
    case FR_RADIUS_CODE_ACCOUNTING_REQUEST:
    case FR_RADIUS_CODE_DISCONNECT_REQUEST:
    case FR_RADIUS_CODE_COA_REQUEST:
      memset(packet + 4, 0, RADIUS_AUTH_VECTOR_LENGTH);
      break;

    case FR_RADIUS_CODE_ACCESS_ACCEPT:
    case FR_RADIUS_CODE_ACCESS_REJECT:
    case FR_RADIUS_CODE_ACCESS_CHALLENGE:
    case FR_RADIUS_CODE_ACCOUNTING_RESPONSE:
    case FR_RADIUS_CODE_DISCONNECT_ACK:
    case FR_RADIUS_CODE_DISCONNECT_NAK:
    case FR_RADIUS_CODE_COA_ACK:
    case FR_RADIUS_CODE_COA_NAK:
    case FR_RADIUS_CODE_PROTOCOL_ERROR:
      if (!vector) goto need_original;
      memcpy(packet + 4, vector, RADIUS_AUTH_VECTOR_LENGTH);
      break;

    case FR_RADIUS_CODE_ACCESS_REQUEST:
    case FR_RADIUS_CODE_STATUS_SERVER:
      /* packet + 4 MUST be the Request Authenticator filled with random data */
      break;

    default:
      goto bad_packet;
    }

    /*
     *  Force Message-Authenticator to be zero,
     *  calculate the HMAC, and put it into the
     *  Message-Authenticator attribute.
     */
    memset(msg + 2, 0, RADIUS_AUTH_VECTOR_LENGTH);
    fr_hmac_md5(msg + 2, packet, packet_len, secret, secret_len);
    break;
  }

  /*
   *  Initialize the request authenticator.
   */
  switch (packet[0]) {
  case FR_RADIUS_CODE_ACCOUNTING_REQUEST:
  case FR_RADIUS_CODE_DISCONNECT_REQUEST:
  case FR_RADIUS_CODE_COA_REQUEST:
    memset(packet + 4, 0, RADIUS_AUTH_VECTOR_LENGTH);
    break;

  case FR_RADIUS_CODE_ACCESS_ACCEPT:
  case FR_RADIUS_CODE_ACCESS_REJECT:
  case FR_RADIUS_CODE_ACCESS_CHALLENGE:
  case FR_RADIUS_CODE_ACCOUNTING_RESPONSE:
  case FR_RADIUS_CODE_DISCONNECT_ACK:
  case FR_RADIUS_CODE_DISCONNECT_NAK:
  case FR_RADIUS_CODE_COA_ACK:
  case FR_RADIUS_CODE_COA_NAK:
  case FR_RADIUS_CODE_PROTOCOL_ERROR:
    if (!vector) {
    need_original:
      fr_strerror_const("Cannot sign response packet without a request packet");
      return -1;
    }
    memcpy(packet + 4, vector, RADIUS_AUTH_VECTOR_LENGTH);
    break;

    /*
     *  The Request Authenticator is random numbers.
     *  We don't need to sign anything else, so
     *  return.
     */
  case FR_RADIUS_CODE_ACCESS_REQUEST:
  case FR_RADIUS_CODE_STATUS_SERVER:
    return 0;

  default:
  bad_packet:
    fr_strerror_printf("Cannot sign unknown packet code %u", packet[0]);
    return -1;
  }

  /*
   *  Request / Response Authenticator = MD5(packet + secret)
   */
  {
    fr_md5_ctx_t  *md5_ctx;

    md5_ctx = fr_md5_ctx_alloc_from_list();
    fr_md5_update(md5_ctx, packet, packet_len);
    fr_md5_update(md5_ctx, secret, secret_len);
    fr_md5_final(packet + 4, md5_ctx);
    fr_md5_ctx_free_from_list(&md5_ctx);
  }

  return 0;
}

char const *fr_radius_decode_fail_reason[FR_RADIUS_FAIL_MAX + 1] = {
  [FR_RADIUS_FAIL_NONE] = "none",
  [FR_RADIUS_FAIL_MIN_LENGTH_PACKET] = "packet is smaller than the minimum packet length",
  [FR_RADIUS_FAIL_MAX_LENGTH_PACKET] = "packet is larger than the maximum packet length",
  [FR_RADIUS_FAIL_MIN_LENGTH_FIELD] = "header 'length' field has a value smaller than the minimum packet length",
  [FR_RADIUS_FAIL_MIN_LENGTH_MISMATCH] = "header 'length' field has a value larger than the received data",
  [FR_RADIUS_FAIL_UNKNOWN_PACKET_CODE] = "unknown packet code",
  [FR_RADIUS_FAIL_UNEXPECTED_REQUEST_CODE] = "unexpected request code",
  [FR_RADIUS_FAIL_UNEXPECTED_RESPONSE_CODE] = "unexpected response code",
  [FR_RADIUS_FAIL_TOO_MANY_ATTRIBUTES] = "packet contains too many attributes",

  [FR_RADIUS_FAIL_INVALID_ATTRIBUTE] = "attribute number 0 is invalid",

  [FR_RADIUS_FAIL_HEADER_OVERFLOW] = "attribute header overflows the packet",
  [FR_RADIUS_FAIL_ATTRIBUTE_TOO_SHORT] = "attribute 'length' field contains invalid value",
  [FR_RADIUS_FAIL_ATTRIBUTE_OVERFLOW] = "attribute 'length' field overflows the packet",
  [FR_RADIUS_FAIL_ATTRIBUTE_DECODE] = "unable to decode attributes",

  [FR_RADIUS_FAIL_MA_INVALID_LENGTH] = "Message-Authenticator has invalid length",
  [FR_RADIUS_FAIL_MA_MISSING] = "Message-Authenticator is required for this packet, but it is missing",
  [FR_RADIUS_FAIL_MA_INVALID] = "Message-Authenticator fails verification. shared secret is incorrect",
  [FR_RADIUS_FAIL_MA_TOO_MANY] = "More than one Message-Authenticator in a packet is invalid",
  [FR_RADIUS_FAIL_PROXY_STATE_MISSING_MA] = "The packet contains Proxy-State, but no Message-Authenticator",

  [FR_RADIUS_FAIL_VERIFY] = "packet fails verification, shared secret is incorrect",
  [FR_RADIUS_FAIL_NO_MATCHING_REQUEST] = "did not find request which matched response",
  [FR_RADIUS_FAIL_IO_ERROR] = "IO error",
  [FR_RADIUS_FAIL_MAX] = "???",
};

/** See if the data pointed to by PTR is a valid RADIUS packet.
 *
 * @param[in] packet    to check.
 * @param[in,out] packet_len_p  The size of the packet data.
 * @param[in] max_attributes  to allow in the packet.
 * @param[in] require_message_authenticator whether we require Message-Authenticator.
 * @param[in] reason    if not NULL, will have the failure reason written to where it points.
 * @return
 *  - True on success.
 *  - False on failure.
 */
bool fr_radius_ok(uint8_t const *packet, size_t *packet_len_p,
      uint32_t max_attributes, bool require_message_authenticator, fr_radius_decode_fail_t *reason)
{
  uint8_t const   *attr, *end;
  size_t      totallen;
  bool      seen_ma = false;
  uint32_t    num_attributes;
  fr_radius_decode_fail_t failure = FR_RADIUS_FAIL_NONE;
  size_t      packet_len = *packet_len_p;

  /*
   *  Check for packets smaller than the packet header.
   *
   *  RFC 2865, Section 3., subsection 'length' says:
   *
   *  "The minimum length is 20 ..."
   */
  if (packet_len < RADIUS_HEADER_LENGTH) {
    failure = FR_RADIUS_FAIL_MIN_LENGTH_PACKET;
    goto finish;
  }


  /*
   *  Check for packets with mismatched size.
   *  i.e. We've received 128 bytes, and the packet header
   *  says it's 256 bytes long.
   */
  totallen = fr_nbo_to_uint16(packet + 2);

  /*
   *  Code of 0 is not understood.
   *  Code of 16 or greater is not understood.
   */
  if ((packet[0] == 0) ||
      (packet[0] >= FR_RADIUS_CODE_MAX)) {
    failure = FR_RADIUS_FAIL_UNKNOWN_PACKET_CODE;
    goto finish;
  }

  switch (packet[0]) {
    /*
     *  Message-Authenticator is required in Status-Server
     *  packets, otherwise they can be trivially forged.
     */
  case FR_RADIUS_CODE_STATUS_SERVER:
    require_message_authenticator = true;
    break;

    /*
     *  Message-Authenticator may or may not be
     *  required for Access-* packets.
     */
  case FR_RADIUS_CODE_ACCESS_REQUEST:
  case FR_RADIUS_CODE_ACCESS_ACCEPT:
  case FR_RADIUS_CODE_ACCESS_CHALLENGE:
  case FR_RADIUS_CODE_ACCESS_REJECT:
  case FR_RADIUS_CODE_PROTOCOL_ERROR:
    break;

    /*
     *  Message-Authenticator is not required for all other packets, but is required if the
     *  caller asks for it.
     */
  case FR_RADIUS_CODE_ACCOUNTING_REQUEST:
  case FR_RADIUS_CODE_ACCOUNTING_RESPONSE:

  case FR_RADIUS_CODE_COA_REQUEST:
  case FR_RADIUS_CODE_COA_ACK:
  case FR_RADIUS_CODE_COA_NAK:

  case FR_RADIUS_CODE_DISCONNECT_REQUEST:
  case FR_RADIUS_CODE_DISCONNECT_ACK:
  case FR_RADIUS_CODE_DISCONNECT_NAK:
    break;

    /*
     *  All other packet codes are not handled by the encoder, so we reject them.
     */
  default:
    failure = FR_RADIUS_FAIL_UNKNOWN_PACKET_CODE;
    goto finish;
  }

  /*
   *  Repeat the length checks.  This time, instead of
   *  looking at the data we received, look at the value
   *  of the 'length' field inside of the packet.
   *
   *  Check for packets smaller than the packet header.
   *
   *  RFC 2865, Section 3., subsection 'length' says:
   *
   *  "The minimum length is 20 ..."
   */
  if (totallen < RADIUS_HEADER_LENGTH) {
    failure = FR_RADIUS_FAIL_MIN_LENGTH_FIELD;
    goto finish;
  }

  /*
   *  And again, for the value of the 'length' field.
   *
   *  RFC 2865, Section 3., subsection 'length' says:
   *
   *  " ... and maximum length is 4096."
   *
   *  HOWEVER.  This requirement is for the network layer.
   *  If the code gets here, we assume that a well-formed
   *  packet is an OK packet.
   *
   *  We allow both the UDP data length, and the RADIUS
   *  "length" field to contain up to 64K of data.
   */

  /*
   *  RFC 2865, Section 3., subsection 'length' says:
   *
   *  "If the packet is shorter than the Length field
   *  indicates, it MUST be silently discarded."
   *
   *  i.e. No response to the NAS.
   */
  if (totallen > packet_len) {
    failure = FR_RADIUS_FAIL_MIN_LENGTH_MISMATCH;
    goto finish;
  }

  /*
   *  RFC 2865, Section 3., subsection 'length' says:
   *
   *  "Octets outside the range of the Length field MUST be
   *  treated as padding and ignored on reception."
   */
  if (totallen < packet_len) {
    *packet_len_p = packet_len = totallen;
  }

  /*
   *  Walk through the packet's attributes, ensuring that
   *  they add up EXACTLY to the size of the packet.
   *
   *  If they don't, then the attributes either under-fill
   *  or over-fill the packet.  Any parsing of the packet
   *  is impossible, and will result in unknown side effects.
   *
   *  This would ONLY happen with buggy RADIUS implementations,
   *  or with an intentional attack.  Either way, we do NOT want
   *  to be vulnerable to this problem.
   */
  attr = packet + RADIUS_HEADER_LENGTH;
  end = packet + packet_len;
  num_attributes = 0;

  while (attr < end) {
    /*
     *  We need at least 2 bytes to check the
     *  attribute header.
     */
    if ((end - attr) < 2) {
      failure = FR_RADIUS_FAIL_HEADER_OVERFLOW;
      goto finish;
    }

    /*
     *  Attribute number zero is NOT defined.
     */
    if (attr[0] == 0) {
      failure = FR_RADIUS_FAIL_INVALID_ATTRIBUTE;
      goto finish;
    }

    /*
     *  Attributes are at LEAST as long as the ID & length
     *  fields.  Anything shorter is an invalid attribute.
     */
    if (attr[1] < 2) {
      failure = FR_RADIUS_FAIL_ATTRIBUTE_TOO_SHORT;
      goto finish;
    }

    /*
     *  If there are fewer bytes in the packet than in the
     *  attribute, it's a bad packet.
     */
    if ((attr + attr[1]) > end) {
      failure = FR_RADIUS_FAIL_ATTRIBUTE_OVERFLOW;
      goto finish;
    }

    /*
     *  Sanity check the attributes for length.
     */
    switch (attr[0]) {
    default:  /* don't do anything by default */
      break;

      /*
       *  If there's an EAP-Message, we require
       *  a Message-Authenticator.
       */
    case FR_EAP_MESSAGE:
      require_message_authenticator = true;
      break;

    case FR_MESSAGE_AUTHENTICATOR:
      if (attr[1] != 2 + RADIUS_AUTH_VECTOR_LENGTH) {
        failure = FR_RADIUS_FAIL_MA_INVALID_LENGTH;
        goto finish;
      }

      /*
       *  Can't have two of them.
       */
      if (seen_ma) {
        failure = FR_RADIUS_FAIL_MA_TOO_MANY;
        goto finish;
      }

      seen_ma = true;
      break;
    }

    attr += attr[1];
    num_attributes++; /* seen one more attribute */

    /*
     *  If we're configured to look for a maximum number of
     *  attributes, and we've seen more than that maximum,
     *  then throw the packet away, as a possible DoS.
     */
    if (num_attributes > max_attributes) {
      failure = FR_RADIUS_FAIL_TOO_MANY_ATTRIBUTES;
      goto finish;
    }
  }

  /*
   *  http://www.freeradius.org/rfc/rfc2869.html#EAP-Message
   *
   *  A packet with an EAP-Message attribute MUST also have
   *  a Message-Authenticator attribute.
   *
   *  A Message-Authenticator all by itself is OK, though.
   *
   *  Similarly, Status-Server packets MUST contain
   *  Message-Authenticator attributes.
   */
  if (require_message_authenticator && !seen_ma) {
    failure = FR_RADIUS_FAIL_MA_MISSING;
    goto finish;
  }

finish:

  if (reason) *reason = failure;

  return (failure == FR_RADIUS_FAIL_NONE);
}


/** Verify the signature of a request / response packet
 *
 *  This function does its work by calling fr_radius_sign(), and then comparing the signature in the packet
 *  with the one we calculated.  If they differ, there's a problem.
 *
 *  @note - We rely on the security of the shared secret for UDP and TCP transport.  For TLS transport, we
 *  rely on TLS to make the RADIUS packets both secure and private.
 *
 *  @note - The BlastRADIUS mitigations require that "require_message_authenticator" and "limit_proxy_state"
 *  are used only for Access-Request packets.  These mitigations MUST NOT be used for any any other packet
 *  codes.
 *
 *  The caller should have called fr_radius_packet_ok() to see if the packet is well-formed, at least for the
 *  base RFC attributes.
 *
 * @param[in] packet        the raw RADIUS packet (request or response)
 * @param[in] vector        the original packet vector
 * @param[in] secret        the shared secret
 * @param[in] secret_len      the length of the secret
 * @param[in] require_message_authenticator whether we require Message-Authenticator.
 * @param[in] limit_proxy_state     whether we allow Proxy-State without Message-Authenticator.
 * @return
 *  < <0 on error (negative fr_radius_decode_fail_t)
 *  - 0 on success.
 */
int fr_radius_verify(uint8_t *packet, uint8_t const *vector,
         uint8_t const *secret, size_t secret_len,
         bool require_message_authenticator, bool limit_proxy_state)
{
  bool    found_message_authenticator = false;
  bool    found_proxy_state = false;
  int   rcode;
  int   code;
  uint8_t   *attr, *msg, *end;
  size_t    packet_len = fr_nbo_to_uint16(packet + 2);
  uint8_t   request_authenticator[RADIUS_AUTH_VECTOR_LENGTH];
  uint8_t   message_authenticator[RADIUS_AUTH_VECTOR_LENGTH];

  if (packet_len < RADIUS_HEADER_LENGTH) {
    fr_strerror_printf("invalid packet length %zu", packet_len);
    return -FR_RADIUS_FAIL_MIN_LENGTH_PACKET;
  }

  code = packet[0];
  if (!code || (code >= FR_RADIUS_CODE_MAX)) {
    fr_strerror_printf("Unknown reply code %d", code);
    return -FR_RADIUS_FAIL_UNKNOWN_PACKET_CODE;
  }

  /*
   *  RFC 5997 says that all Status-Server packets MUST contain Message-Authenticator.
   */
  require_message_authenticator |= (code == FR_RADIUS_CODE_STATUS_SERVER);

  memcpy(request_authenticator, packet + 4, sizeof(request_authenticator));

  /*
   *  Find Message-Authenticator.  Its value has to be
   *  calculated before we calculate the Request
   *  Authenticator or the Response Authenticator.
   */
  msg = NULL;
  attr = packet + RADIUS_HEADER_LENGTH;
  end = packet + packet_len;

  /*
   *  See what we need to do in order to verify the packet.
   *
   *  Note that fr_radius_packet_ok() also does these checks, but it's worth re-doing them here so
   *  that potential API mis-use is safe.  i.e. we do "defense in depth".
   */
  while (attr < end) {
    if ((end - attr) < 2) goto invalid_attribute;

    if (attr[1] < 2) goto invalid_attribute;

    if ((attr + attr[1]) > end) {
    invalid_attribute:
      fr_strerror_printf("invalid attribute at offset %zd", attr - packet);
      return -FR_RADIUS_FAIL_INVALID_ATTRIBUTE;
    }

    /*
     *  If there's no Message-Authenticator, then we need to check Proxy-State, but only if
     *  the caller asked us to limit Proxy-State.
     */
    if (attr[0] == FR_PROXY_STATE) {
      found_proxy_state = limit_proxy_state;
      goto next;
    }

    /*
     *  Check the contents of Message-Authenticator
     */
    if (attr[0] == FR_MESSAGE_AUTHENTICATOR) {
      if (found_message_authenticator) {
        fr_strerror_const("Multiple Message-Authenticators are invalid");
        return -FR_RADIUS_FAIL_MA_TOO_MANY;
      }


      if (attr[1] != 18) {
        fr_strerror_const("too small Message-Authenticator");
        return -FR_RADIUS_FAIL_MA_INVALID_LENGTH;
      }

      /*
       *  If we have found Message-Authenticator, then we verify that.  We also can stop
       *  processing the packet, as we don't care about the contents of Proxy-State.
       */
      memcpy(message_authenticator, attr + 2, sizeof(message_authenticator));
      found_message_authenticator = true;
      msg = attr;
      goto next;
    }

    /*
     *  RFC 3579 Section 3.1 requires Message-Authenticator if the packet contains
     *  EAP-Message.
     */
    if (attr[0] == FR_EAP_MESSAGE) require_message_authenticator = true;

  next:
    attr += attr[1];
  }

  /*
   *  Enforce limit_proxy_state for Access-Request packets.
   */
  if (code == FR_RADIUS_CODE_ACCESS_REQUEST) {
    if (limit_proxy_state && found_proxy_state && !found_message_authenticator) {
      fr_strerror_const("Proxy-State is not allowed without Message-Authenticator");
      return -FR_RADIUS_FAIL_PROXY_STATE_MISSING_MA;
    }
  }

  /*
   *  The require_message_authenticator flag can be set for any of these packet types.  For other
   *  packet types, we check it if it exists, but we allow packets to not contain it.
   */
  if (require_message_authenticator && !found_message_authenticator) {
    fr_strerror_printf("%s is missing the required Message-Authenticator attribute",
           fr_radius_packet_name[code]);
    return -FR_RADIUS_FAIL_MA_MISSING;
  }

  /*
   *  Overwrite the contents of Message-Authenticator
   *  with the one we calculate.
   */
  rcode = fr_radius_sign(packet, vector, secret, secret_len);
  if (rcode < 0) {
    fr_strerror_const_push("Failed calculating correct authenticator");
    return -FR_RADIUS_FAIL_VERIFY;
  }

  /*
   *  Check the Message-Authenticator first.
   *
   *  If it's invalid, restore the original
   *  Message-Authenticator and Request Authenticator
   *  fields.
   *
   *  If it's valid the original and calculated
   *  message authenticators are the same, so we don't
   *  need to do anything.
   */
  if (msg &&
      (fr_digest_cmp(message_authenticator, msg + 2, sizeof(message_authenticator)) != 0)) {
    memcpy(msg + 2, message_authenticator, sizeof(message_authenticator));
    memcpy(packet + 4, request_authenticator, sizeof(request_authenticator));

    fr_strerror_const("invalid Message-Authenticator (shared secret is incorrect)");
    return -FR_RADIUS_FAIL_MA_INVALID;
  }

  /*
   *  These are random numbers, so there's no point in
   *  comparing them.
   */
  if ((code == FR_RADIUS_CODE_ACCESS_REQUEST) || (code == FR_RADIUS_CODE_STATUS_SERVER)) {
    return 0;
  }

  /*
   *  Check the Request Authenticator.
   */
  if (fr_digest_cmp(request_authenticator, packet + 4, sizeof(request_authenticator)) != 0) {
    memcpy(packet + 4, request_authenticator, sizeof(request_authenticator));
    if (vector) {
      fr_strerror_const("invalid Response Authenticator (shared secret is incorrect)");
    } else {
      fr_strerror_const("invalid Request Authenticator (shared secret is incorrect)");
    }
    return -FR_RADIUS_FAIL_VERIFY;
  }

  return 0;
}

void *fr_radius_next_encodable(fr_dcursor_t *cursor, void *current, void *uctx);

void *fr_radius_next_encodable(fr_dcursor_t *cursor, void *current, void *uctx)
{
  fr_pair_t *c = current;
  fr_dict_t *dict = talloc_get_type_abort(uctx, fr_dict_t);

  while ((c = fr_dcursor_list_next(cursor, c))) {
    PAIR_VERIFY(c);
    if ((c->da->dict == dict) &&
        (!c->da->flags.internal || ((c->da->attr > FR_TAG_BASE) && (c->da->attr < (FR_TAG_BASE + 0x20))))) {
      break;
    }
  }

  return c;
}


ssize_t fr_radius_encode(fr_dbuff_t *dbuff, fr_pair_list_t *vps, fr_radius_encode_ctx_t *packet_ctx)
{
  ssize_t     slen;
  fr_pair_t const   *vp;
  fr_dcursor_t    cursor;
  fr_dbuff_t    work_dbuff, length_dbuff;

  /*
   *  The RADIUS header can't do more than 64K of data.
   */
  work_dbuff = FR_DBUFF_MAX(dbuff, 65535);

  FR_DBUFF_IN_BYTES_RETURN(&work_dbuff, packet_ctx->code, packet_ctx->id);
  length_dbuff = FR_DBUFF(&work_dbuff);
  FR_DBUFF_IN_RETURN(&work_dbuff, (uint16_t) RADIUS_HEADER_LENGTH);

  switch (packet_ctx->code) {
  case FR_RADIUS_CODE_ACCESS_REQUEST:
  case FR_RADIUS_CODE_STATUS_SERVER:
    packet_ctx->request_authenticator = fr_dbuff_current(&work_dbuff);

    /*
     *  Allow over-rides of the authentication vector for testing.
     */
    vp = fr_pair_find_by_da(vps, NULL, attr_packet_authentication_vector);
    if (vp && (vp->vp_length >= RADIUS_AUTH_VECTOR_LENGTH)) {
      FR_DBUFF_IN_MEMCPY_RETURN(&work_dbuff, vp->vp_octets, RADIUS_AUTH_VECTOR_LENGTH);
    } else {
      int i;

      for (i = 0; i < 4; i++) {
        FR_DBUFF_IN_RETURN(&work_dbuff, (uint32_t) fr_rand());
      }
    }
    break;

  case FR_RADIUS_CODE_ACCESS_ACCEPT:
  case FR_RADIUS_CODE_ACCESS_REJECT:
  case FR_RADIUS_CODE_ACCESS_CHALLENGE:
  case FR_RADIUS_CODE_ACCOUNTING_RESPONSE:
  case FR_RADIUS_CODE_DISCONNECT_ACK:
  case FR_RADIUS_CODE_DISCONNECT_NAK:
  case FR_RADIUS_CODE_COA_ACK:
  case FR_RADIUS_CODE_COA_NAK:
  case FR_RADIUS_CODE_PROTOCOL_ERROR:
    if (!packet_ctx->request_authenticator) {
      fr_strerror_const("Cannot encode response without request");
      return -1;
    }
    FR_DBUFF_IN_MEMCPY_RETURN(&work_dbuff, packet_ctx->request_authenticator, RADIUS_AUTH_VECTOR_LENGTH);
    break;

  case FR_RADIUS_CODE_ACCOUNTING_REQUEST:
  case FR_RADIUS_CODE_DISCONNECT_REQUEST:
    /*
     *  Tunnel-Password encoded attributes are allowed
     *  in CoA-Request packets, by RFC 5176 Section
     *  3.6.  HOWEVER, the tunnel passwords are
     *  "encrypted" using the Request Authenticator,
     *  which is all zeros!  That makes them much
     *  easier to decrypt.  The only solution here is
     *  to say "don't do that!"
     */
  case FR_RADIUS_CODE_COA_REQUEST:
    packet_ctx->request_authenticator = fr_dbuff_current(&work_dbuff);

    FR_DBUFF_MEMSET_RETURN(&work_dbuff, 0, RADIUS_AUTH_VECTOR_LENGTH);
    break;

  default:
    fr_strerror_printf("Cannot encode unknown packet code %d", packet_ctx->code);
    return -1;
  }

  /*
   *  Always add Message-Authenticator after the packet
   *  header for insecure transport protocols.
   */
  if (!packet_ctx->common->secure_transport) switch (packet_ctx->code) {
  case FR_RADIUS_CODE_ACCESS_ACCEPT:
  case FR_RADIUS_CODE_ACCESS_REJECT:
  case FR_RADIUS_CODE_ACCESS_CHALLENGE:
#ifdef NAS_VIOLATES_RFC
    /*
     *  Allow ridiculous behavior for vendors who violate the RFCs.
     *
     *  But only if there's no EAP-Message in the packet.
     */
    if (packet_ctx->allow_vulnerable_clients && !fr_pair_find_by_da(vps, NULL, attr_eap_message)) {
      break;
    }
    FALL_THROUGH;
#endif

  case FR_RADIUS_CODE_ACCESS_REQUEST:
  case FR_RADIUS_CODE_STATUS_SERVER:
  case FR_RADIUS_CODE_PROTOCOL_ERROR:
    FR_DBUFF_IN_BYTES_RETURN(&work_dbuff, FR_MESSAGE_AUTHENTICATOR, 0x12,
           0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
           0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00);
    packet_ctx->seen_message_authenticator = true;
    break;

  default:
    break;
  }

  /*
   *  If we're sending Protocol-Error, add in
   *  Original-Packet-Code manually.  If the user adds it
   *  later themselves, well, too bad.
   */
  if (packet_ctx->code == FR_RADIUS_CODE_PROTOCOL_ERROR) {
    FR_DBUFF_IN_BYTES_RETURN(&work_dbuff, FR_EXTENDED_ATTRIBUTE_1, 0x07, 0x04 /* Original-Packet-Code */,
           0x00, 0x00, 0x00, packet_ctx->request_code);
  }

  /*
   *  Loop over the reply attributes for the packet.
   */
  fr_pair_dcursor_iter_init(&cursor, vps, fr_radius_next_encodable, dict_radius);
  while ((vp = fr_dcursor_current(&cursor))) {
    PAIR_VERIFY(vp);

    /*
     *  Encode an individual VP
     */
    slen = fr_radius_encode_pair(&work_dbuff, &cursor, packet_ctx);
    if (slen < 0) return slen;
  } /* done looping over all attributes */

  /*
   *  Add Proxy-State to the end of the packet if the caller requested it.
   */
  if (packet_ctx->add_proxy_state) {
    FR_DBUFF_IN_BYTES_RETURN(&work_dbuff, FR_PROXY_STATE, (uint8_t) (2 + sizeof(packet_ctx->common->proxy_state)));
    FR_DBUFF_IN_RETURN(&work_dbuff, packet_ctx->common->proxy_state);
  }

  /*
   *  Fill in the length field we zeroed out earlier.
   *
   */
  fr_dbuff_in(&length_dbuff, (uint16_t) (fr_dbuff_used(&work_dbuff)));

  FR_PROTO_HEX_DUMP(fr_dbuff_start(&work_dbuff), fr_dbuff_used(&work_dbuff), "%s encoded packet", __FUNCTION__);

  return fr_dbuff_set(dbuff, &work_dbuff);
}

ssize_t fr_radius_decode(TALLOC_CTX *ctx, fr_pair_list_t *out,
       uint8_t *packet, size_t packet_len,
       fr_radius_decode_ctx_t *decode_ctx)
{
  ssize_t     slen;
  uint8_t const   *attr, *end;
  static const uint8_t    zeros[RADIUS_AUTH_VECTOR_LENGTH] = {};

  decode_ctx->reason = FR_RADIUS_FAIL_NONE;

  if (!decode_ctx->request_authenticator) {
    switch (packet[0]) {
    case FR_RADIUS_CODE_ACCESS_REQUEST:
    case FR_RADIUS_CODE_STATUS_SERVER:
      decode_ctx->request_authenticator = packet + 4;
      break;

    case FR_RADIUS_CODE_ACCOUNTING_REQUEST:
    case FR_RADIUS_CODE_COA_REQUEST:
    case FR_RADIUS_CODE_DISCONNECT_REQUEST:
      decode_ctx->request_authenticator = zeros;
      break;

    default:
      fr_strerror_const("No authentication vector passed for packet decode");
      decode_ctx->reason = FR_RADIUS_FAIL_NO_MATCHING_REQUEST;
      return -1;
    }
  }

  if (decode_ctx->request_code) {
    unsigned int code = packet[0];

    if (code >= FR_RADIUS_CODE_MAX) {
      decode_ctx->reason = FR_RADIUS_FAIL_UNKNOWN_PACKET_CODE;
      return -1;
    }
    if (decode_ctx->request_code >= FR_RADIUS_CODE_MAX) {
      decode_ctx->reason = FR_RADIUS_FAIL_UNKNOWN_PACKET_CODE;
      return -1;
    }

    if (!allowed_replies[code]) {
      decode_ctx->reason = FR_RADIUS_FAIL_UNEXPECTED_RESPONSE_CODE;
      return -1;
    }

    /*
     *  Protocol error can reply to any packet.
     *
     *  Status-Server can get any reply.
     *
     *  Otherwise the reply code must be associated with the request code we sent.
     */
    if ((allowed_replies[code] != decode_ctx->request_code) &&
        (code != FR_RADIUS_CODE_PROTOCOL_ERROR) &&
        (decode_ctx->request_code != FR_RADIUS_CODE_STATUS_SERVER)) {
      decode_ctx->reason = FR_RADIUS_FAIL_UNEXPECTED_RESPONSE_CODE;
      return -1;
    }
  }

  /*
   *  We can skip verification for dynamic client checks, and where packets are unsigned as with
   *  RADIUS/1.1.
   */
  if (decode_ctx->verify) {
    if (!decode_ctx->request_authenticator) decode_ctx->request_authenticator = zeros;

    if (fr_radius_verify(packet, decode_ctx->request_authenticator,
             (uint8_t const *) decode_ctx->common->secret, decode_ctx->common->secret_length,
             decode_ctx->require_message_authenticator, decode_ctx->limit_proxy_state) < 0) {
      decode_ctx->reason = FR_RADIUS_FAIL_VERIFY;
      return -1;
    }
  }

  attr = packet + 20;
  end = packet + packet_len;

  /*
   *  The caller MUST have called fr_radius_ok() first.  If
   *  he doesn't, all hell breaks loose.
   */
  while (attr < end) {
    slen = fr_radius_decode_pair(ctx, out, attr, (end - attr), decode_ctx);
    if (slen < 0) {
      decode_ctx->reason = FR_RADIUS_FAIL_ATTRIBUTE_DECODE;
      return slen;
    }

    /*
     *  If slen is larger than the room in the packet,
     *  all kinds of bad things happen.
     */
     if (!fr_cond_assert(slen <= (end - attr))) {
       return -slen;
     }

    attr += slen;
    talloc_free_children(decode_ctx->tmp_ctx);
  }

  /*
   *  We've parsed the whole packet, return that.
   */
  return packet_len;
}

/** Simple wrapper for callers who just need a shared secret
 *
 *  @note - All callers verify the packet via fr_radius_packet_verify() before calling this function.
 */
ssize_t fr_radius_decode_simple(TALLOC_CTX *ctx, fr_pair_list_t *out,
        uint8_t *packet, size_t packet_len,
        uint8_t const *vector, char const *secret)
{
  ssize_t rcode;
  fr_radius_ctx_t   common_ctx = {};
  fr_radius_decode_ctx_t  packet_ctx = {};

  common_ctx.secret = secret;
  common_ctx.secret_length = strlen(secret);

  packet_ctx.common = &common_ctx;
  packet_ctx.tmp_ctx = talloc(ctx, uint8_t);
  packet_ctx.request_authenticator = vector;
  packet_ctx.end = packet + packet_len;

  rcode = fr_radius_decode(ctx, out, packet, packet_len, &packet_ctx);
  talloc_free(packet_ctx.tmp_ctx);

  return rcode;
}

int fr_radius_global_init(void)
{
  if (instance_count > 0) {
    instance_count++;
    return 0;
  }

  instance_count++;

  if (fr_dict_autoload(libfreeradius_radius_dict) < 0) {
  fail:
    instance_count--;
    return -1;
  }

  if (fr_dict_attr_autoload(libfreeradius_radius_dict_attr) < 0) {
    fr_dict_autofree(libfreeradius_radius_dict);
    goto fail;
  }

  instantiated = true;
  return 0;
}

void fr_radius_global_free(void)
{
  if (!instantiated) return;

  if (--instance_count != 0) return;

  fr_dict_autofree(libfreeradius_radius_dict);

  instantiated = false;
}

static bool attr_valid(fr_dict_attr_t *da)
{
  fr_radius_attr_flags_t const *flags = fr_radius_attr_flags(da);

  if (da->parent->type == FR_TYPE_STRUCT) {
    if (flags->extended) {
      fr_strerror_const("Attributes with 'extended' flag cannot be used inside of a 'struct'");
      return false;
    }

    if (flags->long_extended) {
      fr_strerror_const("Attributes with 'long_extended' flag cannot be used inside of a 'struct'");
      return false;
    }


    if (flags->concat) {
      fr_strerror_const("Attributes with 'concat' flag cannot be used inside of a 'struct'");
      return false;
    }

    if (flags->has_tag) {
      fr_strerror_const("Attributes with 'tag' flag cannot be used inside of a 'struct'");
      return false;
    }

    if (flags->abinary) {
      fr_strerror_const("Attributes with 'abinary' flag cannot be used inside of a 'struct'");
      return false;
    }

    if (flags->encrypt > 0) {
      fr_strerror_const("Attributes with 'encrypt' flag cannot be used inside of a 'struct'");
      return false;
    }

    return true;
  }

  if (da->flags.length > 253) {
    fr_strerror_printf("Attributes cannot be more than 253 octets in length");
    return false;
  }
  /*
   *  Secret things are secret.
   */
  if (flags->encrypt != 0) da->flags.secret = true;

  if (flags->concat) {
    if (!da->parent->flags.is_root) {
      fr_strerror_const("Attributes with the 'concat' flag MUST be at the root of the dictionary");
      return false;
    }

    if (da->type != FR_TYPE_OCTETS) {
      fr_strerror_const("Attributes with the 'concat' flag MUST be of data type 'octets'");
      return false;
    }

    return true; /* can't use any other flag */
  }

  /*
   *  Tagged attributes can only be of two data types.  They
   *  can, however, be VSAs.
   */
  if (flags->has_tag) {
    if ((da->type != FR_TYPE_UINT32) && (da->type != FR_TYPE_STRING)) {
      fr_strerror_printf("The 'has_tag' flag can only be used for attributes of type 'integer' "
             "or 'string'");
      return false;
    }

    if (!(da->parent->flags.is_root ||
          ((da->parent->type == FR_TYPE_VENDOR) &&
           (da->parent->parent && da->parent->parent->type == FR_TYPE_VSA)))) {
      fr_strerror_const("The 'has_tag' flag can only be used with RFC and VSA attributes");
      return false;
    }

    return true;
  }

  if (flags->extended) {
    if (da->type != FR_TYPE_TLV) {
      fr_strerror_const("The 'long' or 'extended' flag can only be used for attributes of type 'tlv'");
      return false;
    }

    if (!da->parent->flags.is_root) {
      fr_strerror_const("The 'long' flag can only be used for top-level RFC attributes");
      return false;
    }

    return true;
  }

  /*
   *  Stupid hacks for MS-CHAP-MPPE-Keys.  The User-Password
   *  encryption method has no provisions for encoding the
   *  length of the data.  For User-Password, the data is
   *  (presumably) all printable non-zero data.  For
   *  MS-CHAP-MPPE-Keys, the data is binary crap.  So... we
   *  MUST specify a length in the dictionary.
   */
  if ((flags->encrypt == RADIUS_FLAG_ENCRYPT_USER_PASSWORD) && (da->type != FR_TYPE_STRING)) {
    if (da->type != FR_TYPE_OCTETS) {
      fr_strerror_printf("The 'encrypt=User-Password' flag can only be used with "
             "attributes of type 'string'");
      return false;
    }

    if (da->flags.length == 0) {
      fr_strerror_printf("The 'encrypt=User-Password' flag MUST be used with an explicit length for "
             "'octets' data types");
      return false;
    }
  }

  switch (da->type) {
  case FR_TYPE_STRING:
    break;

  case FR_TYPE_TLV:
  case FR_TYPE_IPV4_ADDR:
  case FR_TYPE_UINT32:
  case FR_TYPE_OCTETS:
    if (flags->encrypt != RADIUS_FLAG_ENCRYPT_ASCEND_SECRET) break;
    FALL_THROUGH;

  default:
    if (flags->encrypt) {
      fr_strerror_printf("The 'encrypt' flag cannot be used with attributes of type '%s'",
             fr_type_to_str(da->type));
      return false;
    }
  }

  return true;
}

fr_dict_protocol_t libfreeradius_radius_dict_protocol = {
  .name = "radius",
  .default_type_size = 1,
  .default_type_length = 1,
  .attr = {
    .flags = {
      .table = radius_flags,
      .table_len = NUM_ELEMENTS(radius_flags),
      .len = sizeof(fr_radius_attr_flags_t),
    },
    .valid = attr_valid,
  },

  .init = fr_radius_global_init,
  .free = fr_radius_global_free,

  .decode = fr_radius_decode_foreign,
  .encode = fr_radius_encode_foreign,
};

Coverage Report

Created: 2026-09-28 06:27