dlls/rpcrt4/rpc_assoc.c

   1 /*
   2  * Associations
   3  *
   4  * Copyright 2007 Robert Shearman (for CodeWeavers)
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
  19  *
  20  */
  21
  22 #include <stdarg.h>
  23 #include <assert.h>
  24
  25 #include "rpc.h"
  26 #include "rpcndr.h"
  27 #include "winternl.h"
  28
  29 #include "wine/unicode.h"
  30 #include "wine/debug.h"
  31
  32 #include "rpc_binding.h"
  33 #include "rpc_assoc.h"
  34 #include "rpc_message.h"
  35
  36 WINE_DEFAULT_DEBUG_CHANNEL(rpc);
  37
  38 static CRITICAL_SECTION assoc_list_cs;
  39 static CRITICAL_SECTION_DEBUG assoc_list_cs_debug =
  40 {
  41     0, 0, &assoc_list_cs,
  42     { &assoc_list_cs_debug.ProcessLocksList, &assoc_list_cs_debug.ProcessLocksList },
  43       0, 0, { (DWORD_PTR)(__FILE__ ": assoc_list_cs") }
  44 };
  45 static CRITICAL_SECTION assoc_list_cs = { &assoc_list_cs_debug, -1, 0, 0, 0, 0 };
  46
  47 static struct list client_assoc_list = LIST_INIT(client_assoc_list);
  48 static struct list server_assoc_list = LIST_INIT(server_assoc_list);
  49
  50 static LONG last_assoc_group_id;
  51
  52 typedef struct _RpcContextHandle
  53 {
  54     struct list entry;
  55     void *user_context;
  56     NDR_RUNDOWN rundown_routine;
  57     void *ctx_guard;
  58     UUID uuid;
  59     RTL_RWLOCK rw_lock;
  60     unsigned int refs;
  61 } RpcContextHandle;
  62
  63 static void RpcContextHandle_Destroy(RpcContextHandle *context_handle);
  64
  65 static RPC_STATUS RpcAssoc_Alloc(LPCSTR Protseq, LPCSTR NetworkAddr,
  66                                  LPCSTR Endpoint, LPCWSTR NetworkOptions,
  67                                  RpcAssoc **assoc_out)
  68 {
  69     RpcAssoc *assoc;
  70     assoc = HeapAlloc(GetProcessHeap(), 0, sizeof(*assoc));
  71     if (!assoc)
  72         return RPC_S_OUT_OF_RESOURCES;
  73     assoc->refs = 1;
  74     list_init(&assoc->free_connection_pool);
  75     list_init(&assoc->context_handle_list);
  76     InitializeCriticalSection(&assoc->cs);
  77     assoc->cs.DebugInfo->Spare[0] = (DWORD_PTR)(__FILE__ ": RpcAssoc.cs");
  78     assoc->Protseq = RPCRT4_strdupA(Protseq);
  79     assoc->NetworkAddr = RPCRT4_strdupA(NetworkAddr);
  80     assoc->Endpoint = RPCRT4_strdupA(Endpoint);
  81     assoc->NetworkOptions = NetworkOptions ? RPCRT4_strdupW(NetworkOptions) : NULL;
  82     assoc->assoc_group_id = 0;
  83     list_init(&assoc->entry);
  84     *assoc_out = assoc;
  85     return RPC_S_OK;
  86 }
  87
  88 static BOOL compare_networkoptions(LPCWSTR opts1, LPCWSTR opts2)
  89 {
  90     if ((opts1 == NULL) && (opts2 == NULL))
  91         return TRUE;
  92     if ((opts1 == NULL) || (opts2 == NULL))
  93         return FALSE;
  94     return !strcmpW(opts1, opts2);
  95 }
  96
  97 RPC_STATUS RPCRT4_GetAssociation(LPCSTR Protseq, LPCSTR NetworkAddr,
  98                                  LPCSTR Endpoint, LPCWSTR NetworkOptions,
  99                                  RpcAssoc **assoc_out)
 100 {
 101     RpcAssoc *assoc;
 102     RPC_STATUS status;
 103
 104     EnterCriticalSection(&assoc_list_cs);
 105     LIST_FOR_EACH_ENTRY(assoc, &client_assoc_list, RpcAssoc, entry)
 106     {
 107         if (!strcmp(Protseq, assoc->Protseq) &&
 108             !strcmp(NetworkAddr, assoc->NetworkAddr) &&
 109             !strcmp(Endpoint, assoc->Endpoint) &&
 110             compare_networkoptions(NetworkOptions, assoc->NetworkOptions))
 111         {
 112             assoc->refs++;
 113             *assoc_out = assoc;
 114             LeaveCriticalSection(&assoc_list_cs);
 115             TRACE("using existing assoc %p\n", assoc);
 116             return RPC_S_OK;
 117         }
 118     }
 119
 120     status = RpcAssoc_Alloc(Protseq, NetworkAddr, Endpoint, NetworkOptions, &assoc);
 121     if (status != RPC_S_OK)
 122     {
 123         LeaveCriticalSection(&assoc_list_cs);
 124         return status;
 125     }
 126     list_add_head(&client_assoc_list, &assoc->entry);
 127     *assoc_out = assoc;
 128
 129     LeaveCriticalSection(&assoc_list_cs);
 130
 131     TRACE("new assoc %p\n", assoc);
 132
 133     return RPC_S_OK;
 134 }
 135
 136 RPC_STATUS RpcServerAssoc_GetAssociation(LPCSTR Protseq, LPCSTR NetworkAddr,
 137                                          LPCSTR Endpoint, LPCWSTR NetworkOptions,
 138                                          ULONG assoc_gid,
 139                                          RpcAssoc **assoc_out)
 140 {
 141     RpcAssoc *assoc;
 142     RPC_STATUS status;
 143
 144     EnterCriticalSection(&assoc_list_cs);
 145     if (assoc_gid)
 146     {
 147         LIST_FOR_EACH_ENTRY(assoc, &server_assoc_list, RpcAssoc, entry)
 148         {
 149             /* FIXME: NetworkAddr shouldn't be NULL */
 150             if (assoc->assoc_group_id == assoc_gid &&
 151                 !strcmp(Protseq, assoc->Protseq) &&
 152                 (!NetworkAddr || !assoc->NetworkAddr || !strcmp(NetworkAddr, assoc->NetworkAddr)) &&
 153                 !strcmp(Endpoint, assoc->Endpoint) &&
 154                 ((!assoc->NetworkOptions == !NetworkOptions) &&
 155                  (!NetworkOptions || !strcmpW(NetworkOptions, assoc->NetworkOptions))))
 156             {
 157                 assoc->refs++;
 158                 *assoc_out = assoc;
 159                 LeaveCriticalSection(&assoc_list_cs);
 160                 TRACE("using existing assoc %p\n", assoc);
 161                 return RPC_S_OK;
 162             }
 163         }
 164         *assoc_out = NULL;
 165         LeaveCriticalSection(&assoc_list_cs);
 166         return RPC_S_NO_CONTEXT_AVAILABLE;
 167     }
 168
 169     status = RpcAssoc_Alloc(Protseq, NetworkAddr, Endpoint, NetworkOptions, &assoc);
 170     if (status != RPC_S_OK)
 171     {
 172         LeaveCriticalSection(&assoc_list_cs);
 173         return status;
 174     }
 175     assoc->assoc_group_id = InterlockedIncrement(&last_assoc_group_id);
 176     list_add_head(&server_assoc_list, &assoc->entry);
 177     *assoc_out = assoc;
 178
 179     LeaveCriticalSection(&assoc_list_cs);
 180
 181     TRACE("new assoc %p\n", assoc);
 182
 183     return RPC_S_OK;
 184 }
 185
 186 ULONG RpcAssoc_Release(RpcAssoc *assoc)
 187 {
 188     ULONG refs;
 189
 190     EnterCriticalSection(&assoc_list_cs);
 191     refs = --assoc->refs;
 192     if (!refs)
 193         list_remove(&assoc->entry);
 194     LeaveCriticalSection(&assoc_list_cs);
 195
 196     if (!refs)
 197     {
 198         RpcConnection *Connection, *cursor2;
 199         RpcContextHandle *context_handle, *context_handle_cursor;
 200
 201         TRACE("destroying assoc %p\n", assoc);
 202
 203         LIST_FOR_EACH_ENTRY_SAFE(Connection, cursor2, &assoc->free_connection_pool, RpcConnection, conn_pool_entry)
 204         {
 205             list_remove(&Connection->conn_pool_entry);
 206             RPCRT4_ReleaseConnection(Connection);
 207         }
 208
 209         LIST_FOR_EACH_ENTRY_SAFE(context_handle, context_handle_cursor, &assoc->context_handle_list, RpcContextHandle, entry)
 210             RpcContextHandle_Destroy(context_handle);
 211
 212         HeapFree(GetProcessHeap(), 0, assoc->NetworkOptions);
 213         HeapFree(GetProcessHeap(), 0, assoc->Endpoint);
 214         HeapFree(GetProcessHeap(), 0, assoc->NetworkAddr);
 215         HeapFree(GetProcessHeap(), 0, assoc->Protseq);
 216
 217         assoc->cs.DebugInfo->Spare[0] = 0;
 218         DeleteCriticalSection(&assoc->cs);
 219
 220         HeapFree(GetProcessHeap(), 0, assoc);
 221     }
 222
 223     return refs;
 224 }
 225
 226 #define ROUND_UP(value, alignment) (((value) + ((alignment) - 1)) & ~((alignment)-1))
 227
 228 static RPC_STATUS RpcAssoc_BindConnection(const RpcAssoc *assoc, RpcConnection *conn,
 229                                           const RPC_SYNTAX_IDENTIFIER *InterfaceId,
 230                                           const RPC_SYNTAX_IDENTIFIER *TransferSyntax)
 231 {
 232     RpcPktHdr *hdr;
 233     RpcPktHdr *response_hdr;
 234     RPC_MESSAGE msg;
 235     RPC_STATUS status;
 236     unsigned char *auth_data = NULL;
 237     ULONG auth_length;
 238
 239     TRACE("sending bind request to server\n");
 240
 241     hdr = RPCRT4_BuildBindHeader(NDR_LOCAL_DATA_REPRESENTATION,
 242                                  RPC_MAX_PACKET_SIZE, RPC_MAX_PACKET_SIZE,
 243                                  assoc->assoc_group_id,
 244                                  InterfaceId, TransferSyntax);
 245
 246     status = RPCRT4_Send(conn, hdr, NULL, 0);
 247     RPCRT4_FreeHeader(hdr);
 248     if (status != RPC_S_OK)
 249         return status;
 250
 251     status = RPCRT4_ReceiveWithAuth(conn, &response_hdr, &msg, &auth_data, &auth_length);
 252     if (status != RPC_S_OK)
 253     {
 254         ERR("receive failed with error %d\n", status);
 255         return status;
 256     }
 257
 258     switch (response_hdr->common.ptype)
 259     {
 260     case PKT_BIND_ACK:
 261     {
 262         RpcAddressString *server_address = msg.Buffer;
 263         if ((msg.BufferLength >= FIELD_OFFSET(RpcAddressString, string[0])) ||
 264             (msg.BufferLength >= ROUND_UP(FIELD_OFFSET(RpcAddressString, string[server_address->length]), 4)))
 265         {
 266             unsigned short remaining = msg.BufferLength -
 267             ROUND_UP(FIELD_OFFSET(RpcAddressString, string[server_address->length]), 4);
 268             RpcResultList *results = (RpcResultList*)((ULONG_PTR)server_address +
 269                 ROUND_UP(FIELD_OFFSET(RpcAddressString, string[server_address->length]), 4));
 270             if ((results->num_results == 1) &&
 271                 (remaining >= FIELD_OFFSET(RpcResultList, results[results->num_results])))
 272             {
 273                 switch (results->results[0].result)
 274                 {
 275                 case RESULT_ACCEPT:
 276                     /* respond to authorization request */
 277                     if (auth_length > sizeof(RpcAuthVerifier))
 278                         status = RPCRT4_ClientConnectionAuth(conn,
 279                                                              auth_data + sizeof(RpcAuthVerifier),
 280                                                              auth_length);
 281                     if (status == RPC_S_OK)
 282                     {
 283                         conn->assoc_group_id = response_hdr->bind_ack.assoc_gid;
 284                         conn->MaxTransmissionSize = response_hdr->bind_ack.max_tsize;
 285                         conn->ActiveInterface = *InterfaceId;
 286                     }
 287                     break;
 288                 case RESULT_PROVIDER_REJECTION:
 289                     switch (results->results[0].reason)
 290                     {
 291                     case REASON_ABSTRACT_SYNTAX_NOT_SUPPORTED:
 292                         ERR("syntax %s, %d.%d not supported\n",
 293                             debugstr_guid(&InterfaceId->SyntaxGUID),
 294                             InterfaceId->SyntaxVersion.MajorVersion,
 295                             InterfaceId->SyntaxVersion.MinorVersion);
 296                         status = RPC_S_UNKNOWN_IF;
 297                         break;
 298                     case REASON_TRANSFER_SYNTAXES_NOT_SUPPORTED:
 299                         ERR("transfer syntax not supported\n");
 300                         status = RPC_S_SERVER_UNAVAILABLE;
 301                         break;
 302                     case REASON_NONE:
 303                     default:
 304                         status = RPC_S_CALL_FAILED_DNE;
 305                     }
 306                     break;
 307                 case RESULT_USER_REJECTION:
 308                 default:
 309                     ERR("rejection result %d\n", results->results[0].result);
 310                     status = RPC_S_CALL_FAILED_DNE;
 311                 }
 312             }
 313             else
 314             {
 315                 ERR("incorrect results size\n");
 316                 status = RPC_S_CALL_FAILED_DNE;
 317             }
 318         }
 319         else
 320         {
 321             ERR("bind ack packet too small (%d)\n", msg.BufferLength);
 322             status = RPC_S_PROTOCOL_ERROR;
 323         }
 324         break;
 325     }
 326     case PKT_BIND_NACK:
 327         switch (response_hdr->bind_nack.reject_reason)
 328         {
 329         case REJECT_LOCAL_LIMIT_EXCEEDED:
 330         case REJECT_TEMPORARY_CONGESTION:
 331             ERR("server too busy\n");
 332             status = RPC_S_SERVER_TOO_BUSY;
 333             break;
 334         case REJECT_PROTOCOL_VERSION_NOT_SUPPORTED:
 335             ERR("protocol version not supported\n");
 336             status = RPC_S_PROTOCOL_ERROR;
 337             break;
 338         case REJECT_UNKNOWN_AUTHN_SERVICE:
 339             ERR("unknown authentication service\n");
 340             status = RPC_S_UNKNOWN_AUTHN_SERVICE;
 341             break;
 342         case REJECT_INVALID_CHECKSUM:
 343             ERR("invalid checksum\n");
 344             status = ERROR_ACCESS_DENIED;
 345             break;
 346         default:
 347             ERR("rejected bind for reason %d\n", response_hdr->bind_nack.reject_reason);
 348             status = RPC_S_CALL_FAILED_DNE;
 349         }
 350         break;
 351     default:
 352         ERR("wrong packet type received %d\n", response_hdr->common.ptype);
 353         status = RPC_S_PROTOCOL_ERROR;
 354         break;
 355     }
 356
 357     I_RpcFree(msg.Buffer);
 358     RPCRT4_FreeHeader(response_hdr);
 359     HeapFree(GetProcessHeap(), 0, auth_data);
 360     return status;
 361 }
 362
 363 static RpcConnection *RpcAssoc_GetIdleConnection(RpcAssoc *assoc,
 364                                                  const RPC_SYNTAX_IDENTIFIER *InterfaceId,
 365                                                  const RPC_SYNTAX_IDENTIFIER *TransferSyntax, const RpcAuthInfo *AuthInfo,
 366                                                  const RpcQualityOfService *QOS)
 367 {
 368     RpcConnection *Connection;
 369     EnterCriticalSection(&assoc->cs);
 370     /* try to find a compatible connection from the connection pool */
 371     LIST_FOR_EACH_ENTRY(Connection, &assoc->free_connection_pool, RpcConnection, conn_pool_entry)
 372     {
 373         if (!memcmp(&Connection->ActiveInterface, InterfaceId,
 374                     sizeof(RPC_SYNTAX_IDENTIFIER)) &&
 375             RpcAuthInfo_IsEqual(Connection->AuthInfo, AuthInfo) &&
 376             RpcQualityOfService_IsEqual(Connection->QOS, QOS))
 377         {
 378             list_remove(&Connection->conn_pool_entry);
 379             LeaveCriticalSection(&assoc->cs);
 380             TRACE("got connection from pool %p\n", Connection);
 381             return Connection;
 382         }
 383     }
 384
 385     LeaveCriticalSection(&assoc->cs);
 386     return NULL;
 387 }
 388
 389 RPC_STATUS RpcAssoc_GetClientConnection(RpcAssoc *assoc,
 390                                         const RPC_SYNTAX_IDENTIFIER *InterfaceId,
 391                                         const RPC_SYNTAX_IDENTIFIER *TransferSyntax, RpcAuthInfo *AuthInfo,
 392                                         RpcQualityOfService *QOS, LPCWSTR CookieAuth, RpcConnection **Connection)
 393 {
 394     RpcConnection *NewConnection;
 395     RPC_STATUS status;
 396
 397     *Connection = RpcAssoc_GetIdleConnection(assoc, InterfaceId, TransferSyntax, AuthInfo, QOS);
 398     if (*Connection)
 399         return RPC_S_OK;
 400
 401     /* create a new connection */
 402     status = RPCRT4_CreateConnection(&NewConnection, FALSE /* is this a server connection? */,
 403         assoc->Protseq, assoc->NetworkAddr,
 404         assoc->Endpoint, assoc->NetworkOptions,
 405         AuthInfo, QOS, CookieAuth);
 406     if (status != RPC_S_OK)
 407         return status;
 408
 409     NewConnection->assoc = assoc;
 410     status = RPCRT4_OpenClientConnection(NewConnection);
 411     if (status != RPC_S_OK)
 412     {
 413         RPCRT4_ReleaseConnection(NewConnection);
 414         return status;
 415     }
 416
 417     status = RpcAssoc_BindConnection(assoc, NewConnection, InterfaceId, TransferSyntax);
 418     if (status != RPC_S_OK)
 419     {
 420         RPCRT4_ReleaseConnection(NewConnection);
 421         return status;
 422     }
 423
 424     *Connection = NewConnection;
 425
 426     return RPC_S_OK;
 427 }
 428
 429 void RpcAssoc_ReleaseIdleConnection(RpcAssoc *assoc, RpcConnection *Connection)
 430 {
 431     assert(!Connection->server);
 432     Connection->async_state = NULL;
 433     EnterCriticalSection(&assoc->cs);
 434     if (!assoc->assoc_group_id) assoc->assoc_group_id = Connection->assoc_group_id;
 435     list_add_head(&assoc->free_connection_pool, &Connection->conn_pool_entry);
 436     LeaveCriticalSection(&assoc->cs);
 437 }
 438
 439 RPC_STATUS RpcServerAssoc_AllocateContextHandle(RpcAssoc *assoc, void *CtxGuard,
 440                                                 NDR_SCONTEXT *SContext)
 441 {
 442     RpcContextHandle *context_handle;
 443
 444     context_handle = HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, sizeof(*context_handle));
 445     if (!context_handle)
 446         return ERROR_OUTOFMEMORY;
 447
 448     context_handle->ctx_guard = CtxGuard;
 449     RtlInitializeResource(&context_handle->rw_lock);
 450     context_handle->refs = 1;
 451
 452     /* lock here to mirror unmarshall, so we don't need to special-case the
 453      * freeing of a non-marshalled context handle */
 454     RtlAcquireResourceExclusive(&context_handle->rw_lock, TRUE);
 455
 456     EnterCriticalSection(&assoc->cs);
 457     list_add_tail(&assoc->context_handle_list, &context_handle->entry);
 458     LeaveCriticalSection(&assoc->cs);
 459
 460     *SContext = (NDR_SCONTEXT)context_handle;
 461     return RPC_S_OK;
 462 }
 463
 464 BOOL RpcContextHandle_IsGuardCorrect(NDR_SCONTEXT SContext, void *CtxGuard)
 465 {
 466     RpcContextHandle *context_handle = (RpcContextHandle *)SContext;
 467     return context_handle->ctx_guard == CtxGuard;
 468 }
 469
 470 RPC_STATUS RpcServerAssoc_FindContextHandle(RpcAssoc *assoc, const UUID *uuid,
 471                                             void *CtxGuard, ULONG Flags, NDR_SCONTEXT *SContext)
 472 {
 473     RpcContextHandle *context_handle;
 474
 475     EnterCriticalSection(&assoc->cs);
 476     LIST_FOR_EACH_ENTRY(context_handle, &assoc->context_handle_list, RpcContextHandle, entry)
 477     {
 478         if (RpcContextHandle_IsGuardCorrect((NDR_SCONTEXT)context_handle, CtxGuard) &&
 479             !memcmp(&context_handle->uuid, uuid, sizeof(*uuid)))
 480         {
 481             *SContext = (NDR_SCONTEXT)context_handle;
 482             if (context_handle->refs++)
 483             {
 484                 LeaveCriticalSection(&assoc->cs);
 485                 TRACE("found %p\n", context_handle);
 486                 RtlAcquireResourceExclusive(&context_handle->rw_lock, TRUE);
 487                 return RPC_S_OK;
 488             }
 489         }
 490     }
 491     LeaveCriticalSection(&assoc->cs);
 492
 493     ERR("no context handle found for uuid %s, guard %p\n",
 494         debugstr_guid(uuid), CtxGuard);
 495     return ERROR_INVALID_HANDLE;
 496 }
 497
 498 RPC_STATUS RpcServerAssoc_UpdateContextHandle(RpcAssoc *assoc,
 499                                               NDR_SCONTEXT SContext,
 500                                               void *CtxGuard,
 501                                               NDR_RUNDOWN rundown_routine)
 502 {
 503     RpcContextHandle *context_handle = (RpcContextHandle *)SContext;
 504     RPC_STATUS status;
 505
 506     if (!RpcContextHandle_IsGuardCorrect((NDR_SCONTEXT)context_handle, CtxGuard))
 507         return ERROR_INVALID_HANDLE;
 508
 509     EnterCriticalSection(&assoc->cs);
 510     if (UuidIsNil(&context_handle->uuid, &status))
 511     {
 512         /* add a ref for the data being valid */
 513         context_handle->refs++;
 514         UuidCreate(&context_handle->uuid);
 515         context_handle->rundown_routine = rundown_routine;
 516         TRACE("allocated uuid %s for context handle %p\n",
 517               debugstr_guid(&context_handle->uuid), context_handle);
 518     }
 519     LeaveCriticalSection(&assoc->cs);
 520
 521     return RPC_S_OK;
 522 }
 523
 524 void RpcContextHandle_GetUuid(NDR_SCONTEXT SContext, UUID *uuid)
 525 {
 526     RpcContextHandle *context_handle = (RpcContextHandle *)SContext;
 527     *uuid = context_handle->uuid;
 528 }
 529
 530 static void RpcContextHandle_Destroy(RpcContextHandle *context_handle)
 531 {
 532     TRACE("freeing %p\n", context_handle);
 533
 534     if (context_handle->user_context && context_handle->rundown_routine)
 535     {
 536         TRACE("calling rundown routine %p with user context %p\n",
 537               context_handle->rundown_routine, context_handle->user_context);
 538         context_handle->rundown_routine(context_handle->user_context);
 539     }
 540
 541     RtlDeleteResource(&context_handle->rw_lock);
 542
 543     HeapFree(GetProcessHeap(), 0, context_handle);
 544 }
 545
 546 unsigned int RpcServerAssoc_ReleaseContextHandle(RpcAssoc *assoc, NDR_SCONTEXT SContext, BOOL release_lock)
 547 {
 548     RpcContextHandle *context_handle = (RpcContextHandle *)SContext;
 549     unsigned int refs;
 550
 551     if (release_lock)
 552         RtlReleaseResource(&context_handle->rw_lock);
 553
 554     EnterCriticalSection(&assoc->cs);
 555     refs = --context_handle->refs;
 556     if (!refs)
 557         list_remove(&context_handle->entry);
 558     LeaveCriticalSection(&assoc->cs);
 559
 560     if (!refs)
 561         RpcContextHandle_Destroy(context_handle);
 562
 563     return refs;
 564 }