aad.c

 
#include <freerdp/config.h>
 
#include <stdio.h>
#include <string.h>
 
#include <freerdp/crypto/crypto.h>
#include <freerdp/crypto/privatekey.h>
#include "../crypto/privatekey.h"
#include <freerdp/utils/http.h>
#include <freerdp/utils/aad.h>
 
#include <winpr/crypto.h>
#include <winpr/json.h>
 
#include "transport.h"
 
#include "aad.h"
 
struct rdp_aad
{
  AAD_STATE state;
  rdpContext* rdpcontext;
  rdpTransport* transport;
  char* access_token;
  rdpPrivateKey* key;
  char* kid;
  char* nonce;
  char* hostname;
  char* scope;
  wLog* log;
};
 
#ifdef WITH_AAD
 
static BOOL get_encoded_rsa_params(wLog* wlog, rdpPrivateKey* key, char** e, char** n);
static BOOL generate_pop_key(rdpAad* aad);
 
WINPR_ATTR_FORMAT_ARG(2, 3)
static SSIZE_T stream_sprintf(wStream* s, WINPR_FORMAT_ARG const char* fmt, ...)
{
  va_list ap = { 0 };
  va_start(ap, fmt);
  const int rc = vsnprintf(NULL, 0, fmt, ap);
  va_end(ap);
 
  if (rc < 0)
    return rc;
 
  if (!Stream_EnsureRemainingCapacity(s, (size_t)rc + 1))
    return -1;
 
  char* ptr = Stream_PointerAs(s, char);
  va_start(ap, fmt);
  const int rc2 = vsnprintf(ptr, rc + 1, fmt, ap);
  va_end(ap);
  if (rc != rc2)
    return -23;
  if (!Stream_SafeSeek(s, (size_t)rc2))
    return -3;
  return rc2;
}
 
static BOOL json_get_object(wLog* wlog, WINPR_JSON* json, const char* key, WINPR_JSON** obj)
{
  WINPR_ASSERT(json);
  WINPR_ASSERT(key);
 
  if (!WINPR_JSON_HasObjectItem(json, key))
  {
    WLog_Print(wlog, WLOG_ERROR, "[json] does not contain a key '%s'", key);
    return FALSE;
  }
 
  WINPR_JSON* prop = WINPR_JSON_GetObjectItem(json, key);
  if (!prop)
  {
    WLog_Print(wlog, WLOG_ERROR, "[json] object for key '%s' is NULL", key);
    return FALSE;
  }
  *obj = prop;
  return TRUE;
}
 
static BOOL json_get_number(wLog* wlog, WINPR_JSON* json, const char* key, double* result)
{
  BOOL rc = FALSE;
  WINPR_JSON* prop = NULL;
  if (!json_get_object(wlog, json, key, &prop))
    return FALSE;
 
  if (!WINPR_JSON_IsNumber(prop))
  {
    WLog_Print(wlog, WLOG_ERROR, "[json] object for key '%s' is NOT a NUMBER", key);
    goto fail;
  }
 
  *result = WINPR_JSON_GetNumberValue(prop);
 
  rc = TRUE;
fail:
  return rc;
}
 
static BOOL json_get_const_string(wLog* wlog, WINPR_JSON* json, const char* key,
                                  const char** result)
{
  BOOL rc = FALSE;
  WINPR_ASSERT(result);
 
  *result = NULL;
 
  WINPR_JSON* prop = NULL;
  if (!json_get_object(wlog, json, key, &prop))
    return FALSE;
 
  if (!WINPR_JSON_IsString(prop))
  {
    WLog_Print(wlog, WLOG_ERROR, "[json] object for key '%s' is NOT a STRING", key);
    goto fail;
  }
 
  const char* str = WINPR_JSON_GetStringValue(prop);
  if (!str)
    WLog_Print(wlog, WLOG_ERROR, "[json] object for key '%s' is NULL", key);
  *result = str;
  rc = str != NULL;
 
fail:
  return rc;
}
 
static BOOL json_get_string_alloc(wLog* wlog, WINPR_JSON* json, const char* key, char** result)
{
  const char* str = NULL;
  if (!json_get_const_string(wlog, json, key, &str))
    return FALSE;
  free(*result);
  *result = _strdup(str);
  if (!*result)
    WLog_Print(wlog, WLOG_ERROR, "[json] object for key '%s' strdup is NULL", key);
  return *result != NULL;
}
 
static INLINE const char* aad_auth_result_to_string(DWORD code)
{
#define ERROR_CASE(cd, x)   \
  if ((cd) == (DWORD)(x)) \
    return #x;
 
  ERROR_CASE(code, S_OK)
  ERROR_CASE(code, SEC_E_INVALID_TOKEN)
  ERROR_CASE(code, E_ACCESSDENIED)
  ERROR_CASE(code, STATUS_LOGON_FAILURE)
  ERROR_CASE(code, STATUS_NO_LOGON_SERVERS)
  ERROR_CASE(code, STATUS_INVALID_LOGON_HOURS)
  ERROR_CASE(code, STATUS_INVALID_WORKSTATION)
  ERROR_CASE(code, STATUS_PASSWORD_EXPIRED)
  ERROR_CASE(code, STATUS_ACCOUNT_DISABLED)
  return "Unknown error";
}
 
static BOOL aad_get_nonce(rdpAad* aad)
{
  BOOL ret = FALSE;
  BYTE* response = NULL;
  long resp_code = 0;
  size_t response_length = 0;
  WINPR_JSON* json = NULL;
 
  if (!freerdp_http_request("https://login.microsoftonline.com/common/oauth2/v2.0/token",
                            "grant_type=srv_challenge", &resp_code, &response, &response_length))
  {
    WLog_Print(aad->log, WLOG_ERROR, "nonce request failed");
    goto fail;
  }
 
  if (resp_code != HTTP_STATUS_OK)
  {
    WLog_Print(aad->log, WLOG_ERROR,
               "Server unwilling to provide nonce; returned status code %li", resp_code);
    if (response_length > 0)
      WLog_Print(aad->log, WLOG_ERROR, "[status message] %s", response);
    goto fail;
  }
 
  json = WINPR_JSON_ParseWithLength((const char*)response, response_length);
  if (!json)
  {
    WLog_Print(aad->log, WLOG_ERROR, "Failed to parse nonce response");
    goto fail;
  }
 
  if (!json_get_string_alloc(aad->log, json, "Nonce", &aad->nonce))
    goto fail;
 
  ret = TRUE;
 
fail:
  free(response);
  WINPR_JSON_Delete(json);
  return ret;
}
 
int aad_client_begin(rdpAad* aad)
{
  size_t size = 0;
 
  WINPR_ASSERT(aad);
  WINPR_ASSERT(aad->rdpcontext);
 
  rdpSettings* settings = aad->rdpcontext->settings;
  WINPR_ASSERT(settings);
 
  freerdp* instance = aad->rdpcontext->instance;
  WINPR_ASSERT(instance);
 
  /* Get the host part of the hostname */
  const char* hostname = freerdp_settings_get_string(settings, FreeRDP_AadServerHostname);
  if (!hostname)
    hostname = freerdp_settings_get_string(settings, FreeRDP_ServerHostname);
  if (!hostname)
  {
    WLog_Print(aad->log, WLOG_ERROR, "FreeRDP_ServerHostname == NULL");
    return -1;
  }
 
  aad->hostname = _strdup(hostname);
  if (!aad->hostname)
  {
    WLog_Print(aad->log, WLOG_ERROR, "_strdup(FreeRDP_ServerHostname) == NULL");
    return -1;
  }
 
  char* p = strchr(aad->hostname, '.');
  if (p)
    *p = '\0';
 
  if (winpr_asprintf(&aad->scope, &size,
                     "ms-device-service%%3A%%2F%%2Ftermsrv.wvd.microsoft.com%%2Fname%%2F%s%%"
                     "2Fuser_impersonation",
                     aad->hostname) <= 0)
    return -1;
 
  if (!generate_pop_key(aad))
    return -1;
 
  /* Obtain an oauth authorization code */
  if (!instance->GetAccessToken)
  {
    WLog_Print(aad->log, WLOG_ERROR, "instance->GetAccessToken == NULL");
    return -1;
  }
  const BOOL arc = instance->GetAccessToken(instance, ACCESS_TOKEN_TYPE_AAD, &aad->access_token,
                                            2, aad->scope, aad->kid);
  if (!arc)
  {
    WLog_Print(aad->log, WLOG_ERROR, "Unable to obtain access token");
    return -1;
  }
 
  /* Send the nonce request message */
  if (!aad_get_nonce(aad))
  {
    WLog_Print(aad->log, WLOG_ERROR, "Unable to obtain nonce");
    return -1;
  }
 
  return 1;
}
 
static char* aad_create_jws_header(rdpAad* aad)
{
  WINPR_ASSERT(aad);
 
  /* Construct the base64url encoded JWS header */
  char* buffer = NULL;
  size_t bufferlen = 0;
  const int length =
      winpr_asprintf(&buffer, &bufferlen, "{\"alg\":\"RS256\",\"kid\":\"%s\"}", aad->kid);
  if (length < 0)
    return NULL;
 
  char* jws_header = crypto_base64url_encode((const BYTE*)buffer, bufferlen);
  free(buffer);
  return jws_header;
}
 
static char* aad_create_jws_payload(rdpAad* aad, const char* ts_nonce)
{
  const time_t ts = time(NULL);
 
  WINPR_ASSERT(aad);
 
  char* e = NULL;
  char* n = NULL;
  if (!get_encoded_rsa_params(aad->log, aad->key, &e, &n))
    return NULL;
 
  /* Construct the base64url encoded JWS payload */
  char* buffer = NULL;
  size_t bufferlen = 0;
  const int length =
      winpr_asprintf(&buffer, &bufferlen,
                     "{"
                     "\"ts\":\"%li\","
                     "\"at\":\"%s\","
                     "\"u\":\"ms-device-service://termsrv.wvd.microsoft.com/name/%s\","
                     "\"nonce\":\"%s\","
                     "\"cnf\":{\"jwk\":{\"kty\":\"RSA\",\"e\":\"%s\",\"n\":\"%s\"}},"
                     "\"client_claims\":\"{\\\"aad_nonce\\\":\\\"%s\\\"}\""
                     "}",
                     ts, aad->access_token, aad->hostname, ts_nonce, e, n, aad->nonce);
  free(e);
  free(n);
 
  if (length < 0)
    return NULL;
 
  char* jws_payload = crypto_base64url_encode((BYTE*)buffer, bufferlen);
  free(buffer);
  return jws_payload;
}
 
static BOOL aad_update_digest(rdpAad* aad, WINPR_DIGEST_CTX* ctx, const char* what)
{
  WINPR_ASSERT(aad);
  WINPR_ASSERT(ctx);
  WINPR_ASSERT(what);
 
  const BOOL dsu1 = winpr_DigestSign_Update(ctx, what, strlen(what));
  if (!dsu1)
  {
    WLog_Print(aad->log, WLOG_ERROR, "winpr_DigestSign_Update [%s] failed", what);
    return FALSE;
  }
  return TRUE;
}
 
static char* aad_final_digest(rdpAad* aad, WINPR_DIGEST_CTX* ctx)
{
  char* jws_signature = NULL;
 
  WINPR_ASSERT(aad);
  WINPR_ASSERT(ctx);
 
  size_t siglen = 0;
  const int dsf = winpr_DigestSign_Final(ctx, NULL, &siglen);
  if (dsf <= 0)
  {
    WLog_Print(aad->log, WLOG_ERROR, "winpr_DigestSign_Final failed with %d", dsf);
    return FALSE;
  }
 
  char* buffer = calloc(siglen + 1, sizeof(char));
  if (!buffer)
  {
    WLog_Print(aad->log, WLOG_ERROR, "calloc %" PRIuz " bytes failed", siglen + 1);
    goto fail;
  }
 
  size_t fsiglen = siglen;
  const int dsf2 = winpr_DigestSign_Final(ctx, (BYTE*)buffer, &fsiglen);
  if (dsf2 <= 0)
  {
    WLog_Print(aad->log, WLOG_ERROR, "winpr_DigestSign_Final failed with %d", dsf2);
    goto fail;
  }
 
  if (siglen != fsiglen)
  {
    WLog_Print(aad->log, WLOG_ERROR,
               "winpr_DigestSignFinal returned different sizes, first %" PRIuz " then %" PRIuz,
               siglen, fsiglen);
    goto fail;
  }
  jws_signature = crypto_base64url_encode((const BYTE*)buffer, fsiglen);
fail:
  free(buffer);
  return jws_signature;
}
 
static char* aad_create_jws_signature(rdpAad* aad, const char* jws_header, const char* jws_payload)
{
  char* jws_signature = NULL;
 
  WINPR_ASSERT(aad);
 
  WINPR_DIGEST_CTX* md_ctx = freerdp_key_digest_sign(aad->key, WINPR_MD_SHA256);
  if (!md_ctx)
  {
    WLog_Print(aad->log, WLOG_ERROR, "winpr_Digest_New failed");
    goto fail;
  }
 
  if (!aad_update_digest(aad, md_ctx, jws_header))
    goto fail;
  if (!aad_update_digest(aad, md_ctx, "."))
    goto fail;
  if (!aad_update_digest(aad, md_ctx, jws_payload))
    goto fail;
 
  jws_signature = aad_final_digest(aad, md_ctx);
fail:
  winpr_Digest_Free(md_ctx);
  return jws_signature;
}
 
static int aad_send_auth_request(rdpAad* aad, const char* ts_nonce)
{
  int ret = -1;
  char* jws_header = NULL;
  char* jws_payload = NULL;
  char* jws_signature = NULL;
 
  WINPR_ASSERT(aad);
  WINPR_ASSERT(ts_nonce);
 
  wStream* s = Stream_New(NULL, 1024);
  if (!s)
    goto fail;
 
  /* Construct the base64url encoded JWS header */
  jws_header = aad_create_jws_header(aad);
  if (!jws_header)
    goto fail;
 
  /* Construct the base64url encoded JWS payload */
  jws_payload = aad_create_jws_payload(aad, ts_nonce);
  if (!jws_payload)
    goto fail;
 
  /* Sign the JWS with the pop key */
  jws_signature = aad_create_jws_signature(aad, jws_header, jws_payload);
  if (!jws_signature)
    goto fail;
 
  /* Construct the Authentication Request PDU with the JWS as the RDP Assertion */
  if (stream_sprintf(s, "{\"rdp_assertion\":\"%s.%s.%s\"}", jws_header, jws_payload,
                     jws_signature) < 0)
    goto fail;
 
  /* Include null terminator in PDU */
  Stream_Write_UINT8(s, 0);
 
  Stream_SealLength(s);
 
  if (transport_write(aad->transport, s) < 0)
  {
    WLog_Print(aad->log, WLOG_ERROR, "transport_write [%" PRIdz " bytes] failed",
               Stream_Length(s));
  }
  else
  {
    ret = 1;
    aad->state = AAD_STATE_AUTH;
  }
fail:
  Stream_Free(s, TRUE);
  free(jws_header);
  free(jws_payload);
  free(jws_signature);
 
  return ret;
}
 
static int aad_parse_state_initial(rdpAad* aad, wStream* s)
{
  const char* jstr = Stream_PointerAs(s, char);
  const size_t jlen = Stream_GetRemainingLength(s);
  const char* ts_nonce = NULL;
  int ret = -1;
  WINPR_JSON* json = NULL;
 
  if (!Stream_SafeSeek(s, jlen))
    goto fail;
 
  json = WINPR_JSON_ParseWithLength(jstr, jlen);
  if (!json)
    goto fail;
 
  if (!json_get_const_string(aad->log, json, "ts_nonce", &ts_nonce))
    goto fail;
 
  ret = aad_send_auth_request(aad, ts_nonce);
fail:
  WINPR_JSON_Delete(json);
  return ret;
}
 
static int aad_parse_state_auth(rdpAad* aad, wStream* s)
{
  int rc = -1;
  double result = 0;
  DWORD error_code = 0;
  WINPR_JSON* json = NULL;
  const char* jstr = Stream_PointerAs(s, char);
  const size_t jlength = Stream_GetRemainingLength(s);
 
  if (!Stream_SafeSeek(s, jlength))
    goto fail;
 
  json = WINPR_JSON_ParseWithLength(jstr, jlength);
  if (!json)
    goto fail;
 
  if (!json_get_number(aad->log, json, "authentication_result", &result))
    goto fail;
  error_code = (DWORD)result;
 
  if (error_code != S_OK)
  {
    WLog_Print(aad->log, WLOG_ERROR, "Authentication result: %s (0x%08" PRIx32 ")",
               aad_auth_result_to_string(error_code), error_code);
    goto fail;
  }
  aad->state = AAD_STATE_FINAL;
  rc = 1;
fail:
  WINPR_JSON_Delete(json);
  return rc;
}
 
int aad_recv(rdpAad* aad, wStream* s)
{
  WINPR_ASSERT(aad);
  WINPR_ASSERT(s);
 
  switch (aad->state)
  {
    case AAD_STATE_INITIAL:
      return aad_parse_state_initial(aad, s);
    case AAD_STATE_AUTH:
      return aad_parse_state_auth(aad, s);
    case AAD_STATE_FINAL:
    default:
      WLog_Print(aad->log, WLOG_ERROR, "Invalid AAD_STATE %d", aad->state);
      return -1;
  }
}
 
static BOOL generate_rsa_2048(rdpAad* aad)
{
  WINPR_ASSERT(aad);
  return freerdp_key_generate(aad->key, 2048);
}
 
static char* generate_rsa_digest_base64_str(rdpAad* aad, const char* input, size_t ilen)
{
  char* b64 = NULL;
  WINPR_DIGEST_CTX* digest = winpr_Digest_New();
  if (!digest)
  {
    WLog_Print(aad->log, WLOG_ERROR, "winpr_Digest_New failed");
    goto fail;
  }
 
  if (!winpr_Digest_Init(digest, WINPR_MD_SHA256))
  {
    WLog_Print(aad->log, WLOG_ERROR, "winpr_Digest_Init(WINPR_MD_SHA256) failed");
    goto fail;
  }
 
  if (!winpr_Digest_Update(digest, (const BYTE*)input, ilen))
  {
    WLog_Print(aad->log, WLOG_ERROR, "winpr_Digest_Update(%" PRIuz ") failed", ilen);
    goto fail;
  }
 
  BYTE hash[WINPR_SHA256_DIGEST_LENGTH] = { 0 };
  if (!winpr_Digest_Final(digest, hash, sizeof(hash)))
  {
    WLog_Print(aad->log, WLOG_ERROR, "winpr_Digest_Final(%" PRIuz ") failed", sizeof(hash));
    goto fail;
  }
 
  /* Base64url encode the hash */
  b64 = crypto_base64url_encode(hash, sizeof(hash));
 
fail:
  winpr_Digest_Free(digest);
  return b64;
}
 
static BOOL generate_json_base64_str(rdpAad* aad, const char* b64_hash)
{
  WINPR_ASSERT(aad);
 
  char* buffer = NULL;
  size_t blen = 0;
  const int length = winpr_asprintf(&buffer, &blen, "{\"kid\":\"%s\"}", b64_hash);
  if (length < 0)
    return FALSE;
 
  /* Finally, base64url encode the JSON text to form the kid */
  free(aad->kid);
  aad->kid = crypto_base64url_encode((const BYTE*)buffer, (size_t)length);
  free(buffer);
 
  if (!aad->kid)
  {
    return FALSE;
  }
  return TRUE;
}
 
BOOL generate_pop_key(rdpAad* aad)
{
  BOOL ret = FALSE;
  char* buffer = NULL;
  char* b64_hash = NULL;
  char* e = NULL;
  char* n = NULL;
 
  WINPR_ASSERT(aad);
 
  /* Generate a 2048-bit RSA key pair */
  if (!generate_rsa_2048(aad))
    goto fail;
 
  /* Encode the public key as a JWK */
  if (!get_encoded_rsa_params(aad->log, aad->key, &e, &n))
    goto fail;
 
  size_t blen = 0;
  const int alen =
      winpr_asprintf(&buffer, &blen, "{\"e\":\"%s\",\"kty\":\"RSA\",\"n\":\"%s\"}", e, n);
  if (alen < 0)
    goto fail;
 
  /* Hash the encoded public key */
  b64_hash = generate_rsa_digest_base64_str(aad, buffer, blen);
  if (!b64_hash)
    goto fail;
 
  /* Encode a JSON object with a single property "kid" whose value is the encoded hash */
  ret = generate_json_base64_str(aad, b64_hash);
 
fail:
  free(b64_hash);
  free(buffer);
  free(e);
  free(n);
  return ret;
}
 
static char* bn_to_base64_url(wLog* wlog, rdpPrivateKey* key, enum FREERDP_KEY_PARAM param)
{
  WINPR_ASSERT(wlog);
  WINPR_ASSERT(key);
 
  size_t len = 0;
  BYTE* bn = freerdp_key_get_param(key, param, &len);
  if (!bn)
    return NULL;
 
  char* b64 = crypto_base64url_encode(bn, len);
  free(bn);
 
  if (!b64)
    WLog_Print(wlog, WLOG_ERROR, "failed  base64 url encode BIGNUM");
 
  return b64;
}
 
BOOL get_encoded_rsa_params(wLog* wlog, rdpPrivateKey* key, char** pe, char** pn)
{
  BOOL rc = FALSE;
  char* e = NULL;
  char* n = NULL;
 
  WINPR_ASSERT(wlog);
  WINPR_ASSERT(key);
  WINPR_ASSERT(pe);
  WINPR_ASSERT(pn);
 
  *pe = NULL;
  *pn = NULL;
 
  e = bn_to_base64_url(wlog, key, FREERDP_KEY_PARAM_RSA_E);
  if (!e)
  {
    WLog_Print(wlog, WLOG_ERROR, "failed  base64 url encode RSA E");
    goto fail;
  }
 
  n = bn_to_base64_url(wlog, key, FREERDP_KEY_PARAM_RSA_N);
  if (!n)
  {
    WLog_Print(wlog, WLOG_ERROR, "failed  base64 url encode RSA N");
    goto fail;
  }
 
  rc = TRUE;
fail:
  if (!rc)
  {
    free(e);
    free(n);
  }
  else
  {
    *pe = e;
    *pn = n;
  }
  return rc;
}
#else
int aad_client_begin(rdpAad* aad)
{
  WINPR_ASSERT(aad);
  WLog_Print(aad->log, WLOG_ERROR, "AAD security not compiled in, aborting!");
  return -1;
}
int aad_recv(rdpAad* aad, wStream* s)
{
  WINPR_ASSERT(aad);
  WLog_Print(aad->log, WLOG_ERROR, "AAD security not compiled in, aborting!");
  return -1;
}
#endif
 
rdpAad* aad_new(rdpContext* context, rdpTransport* transport)
{
  WINPR_ASSERT(transport);
  WINPR_ASSERT(context);
 
  rdpAad* aad = (rdpAad*)calloc(1, sizeof(rdpAad));
 
  if (!aad)
    return NULL;
 
  aad->log = WLog_Get(FREERDP_TAG("aad"));
  aad->key = freerdp_key_new();
  if (!aad->key)
    goto fail;
  aad->rdpcontext = context;
  aad->transport = transport;
 
  return aad;
fail:
  WINPR_PRAGMA_DIAG_PUSH
  WINPR_PRAGMA_DIAG_IGNORED_MISMATCHED_DEALLOC
  aad_free(aad);
  WINPR_PRAGMA_DIAG_POP
  return NULL;
}
 
void aad_free(rdpAad* aad)
{
  if (!aad)
    return;
 
  free(aad->hostname);
  free(aad->scope);
  free(aad->nonce);
  free(aad->access_token);
  free(aad->kid);
  freerdp_key_free(aad->key);
 
  free(aad);
}
 
AAD_STATE aad_get_state(rdpAad* aad)
{
  WINPR_ASSERT(aad);
  return aad->state;
}
 
BOOL aad_is_supported(void)
{
#ifdef WITH_AAD
  return TRUE;
#else
  return FALSE;
#endif
}
 
#ifdef WITH_AAD
char* freerdp_utils_aad_get_access_token(wLog* log, const char* data, size_t length)
{
  char* token = NULL;
  WINPR_JSON* access_token_prop = NULL;
  const char* access_token_str = NULL;
 
  WINPR_JSON* json = WINPR_JSON_ParseWithLength(data, length);
  if (!json)
  {
    WLog_Print(log, WLOG_ERROR, "Failed to parse access token response [got %" PRIuz " bytes",
               length);
    goto cleanup;
  }
 
  access_token_prop = WINPR_JSON_GetObjectItem(json, "access_token");
  if (!access_token_prop)
  {
    WLog_Print(log, WLOG_ERROR, "Response has no \"access_token\" property");
    goto cleanup;
  }
 
  access_token_str = WINPR_JSON_GetStringValue(access_token_prop);
  if (!access_token_str)
  {
    WLog_Print(log, WLOG_ERROR, "Invalid value for \"access_token\"");
    goto cleanup;
  }
 
  token = _strdup(access_token_str);
 
cleanup:
  WINPR_JSON_Delete(json);
  return token;
}
#endif