afd: use a simpler method to create AFD helper handles

src/afd.c

@@ -10,120 +10,50 @@
 
 #define IOCTL_AFD_POLL 0x00012024
 
-/* clang-format off */
-static const GUID AFD__PROVIDER_GUID_LIST[] = {
-  /* MSAFD Tcpip [TCP+UDP+RAW / IP] */
-  {0xe70f1aa0, 0xab8b, 0x11cf,
-   {0x8c, 0xa3, 0x00, 0x80, 0x5f, 0x48, 0xa1, 0x92}},
-  /* MSAFD Tcpip [TCP+UDP+RAW / IPv6] */
-  {0xf9eab0c0, 0x26d4, 0x11d0,
-   {0xbb, 0xbf, 0x00, 0xaa, 0x00, 0x6c, 0x34, 0xe4}},
-  /* MSAFD RfComm [Bluetooth] */
-  {0x9fc48064, 0x7298, 0x43e4,
-   {0xb7, 0xbd, 0x18, 0x1f, 0x20, 0x89, 0x79, 0x2a}},
-  /* MSAFD Irda [IrDA] */
-  {0x3972523d, 0x2af1, 0x11d1,
-   {0xb6, 0x55, 0x00, 0x80, 0x5f, 0x36, 0x42, 0xcc}}};
-/* clang-format on */
-
-static const int AFD__ANY_PROTOCOL = -1;
-
-/* This protocol info record is used by afd_create_driver_socket() to create
- * sockets that can be used as the first argument to afd_poll(). It is
- * populated on startup by afd_global_init(). */
-static WSAPROTOCOL_INFOW afd__driver_socket_protocol_info;
-
-static const WSAPROTOCOL_INFOW* afd__find_protocol_info(
-    const WSAPROTOCOL_INFOW* infos, size_t infos_count, int protocol_id) {
-  size_t i, j;
-
-  for (i = 0; i < infos_count; i++) {
-    const WSAPROTOCOL_INFOW* info = &infos[i];
-
-    /* Apply protocol id filter. */
-    if (protocol_id != AFD__ANY_PROTOCOL && protocol_id != info->iProtocol)
-      continue;
-
-    /* Filter out non-MSAFD protocols. */
-    for (j = 0; j < array_count(AFD__PROVIDER_GUID_LIST); j++) {
-      if (memcmp(&info->ProviderId,
-                 &AFD__PROVIDER_GUID_LIST[j],
-                 sizeof info->ProviderId) == 0)
-        return info;
-    }
-  }
-
-  return NULL; /* Not found. */
-}
-
-int afd_global_init(void) {
-  WSAPROTOCOL_INFOW* infos;
-  size_t infos_count;
-  const WSAPROTOCOL_INFOW* afd_info;
-
-  /* Load the winsock catalog. */
-  if (ws_get_protocol_catalog(&infos, &infos_count) < 0)
-    return -1;
-
-  /* Find a WSAPROTOCOL_INFOW structure that we can use to create an MSAFD
-   * socket. Preferentially we pick a UDP socket, otherwise try TCP or any
-   * other type. */
-  for (;;) {
-    afd_info = afd__find_protocol_info(infos, infos_count, IPPROTO_UDP);
-    if (afd_info != NULL)
-      break;
-
-    afd_info = afd__find_protocol_info(infos, infos_count, IPPROTO_TCP);
-    if (afd_info != NULL)
-      break;
-
-    afd_info = afd__find_protocol_info(infos, infos_count, AFD__ANY_PROTOCOL);
-    if (afd_info != NULL)
-      break;
-
-    free(infos);
-    return_set_error(-1, WSAENETDOWN); /* No suitable protocol found. */
-  }
-
-  /* Copy found protocol information from the catalog to a static buffer. */
-  afd__driver_socket_protocol_info = *afd_info;
+static UNICODE_STRING afd__helper_name =
+    RTL_CONSTANT_STRING(L"\\Device\\Afd\\Wepoll");
 
-  free(infos);
-  return 0;
-}
-
-int afd_create_driver_socket(HANDLE iocp, SOCKET* driver_socket_out) {
-  SOCKET socket;
+static OBJECT_ATTRIBUTES afd__helper_attributes =
+    RTL_CONSTANT_OBJECT_ATTRIBUTES(&afd__helper_name, 0);
 
-  socket = WSASocketW(afd__driver_socket_protocol_info.iAddressFamily,
-                      afd__driver_socket_protocol_info.iSocketType,
-                      afd__driver_socket_protocol_info.iProtocol,
-                      &afd__driver_socket_protocol_info,
-                      0,
-                      WSA_FLAG_OVERLAPPED);
-  if (socket == INVALID_SOCKET)
-    return_map_error(-1);
+int afd_create_helper_handle(HANDLE iocp, HANDLE* afd_helper_handle_out) {
+  HANDLE afd_helper_handle;
+  IO_STATUS_BLOCK iosb;
+  NTSTATUS status;
 
-  /* TODO: use WSA_FLAG_NOINHERIT on Windows versions that support it. */
-  if (!SetHandleInformation((HANDLE) socket, HANDLE_FLAG_INHERIT, 0))
-    goto error;
+  /* By opening \Device\Afd without specifying any extended attributes, we'll
+   * get a handle that lets us talk to the AFD driver, but that doesn't have an
+   * associated endpoint (so it's not a socket). */
+  status = NtCreateFile(&afd_helper_handle,
+                        SYNCHRONIZE,
+                        &afd__helper_attributes,
+                        &iosb,
+                        NULL,
+                        0,
+                        FILE_SHARE_READ | FILE_SHARE_WRITE,
+                        FILE_OPEN,
+                        0,
+                        NULL,
+                        0);
+  if (status != STATUS_SUCCESS)
+    return_set_error(-1, RtlNtStatusToDosError(status));
 
-  if (CreateIoCompletionPort((HANDLE) socket, iocp, 0, 0) == NULL)
+  if (CreateIoCompletionPort(afd_helper_handle, iocp, 0, 0) == NULL)
     goto error;
 
-  if (!SetFileCompletionNotificationModes((HANDLE) socket,
+  if (!SetFileCompletionNotificationModes(afd_helper_handle,
                                           FILE_SKIP_SET_EVENT_ON_HANDLE))
     goto error;
 
-  *driver_socket_out = socket;
+  *afd_helper_handle_out = afd_helper_handle;
   return 0;
 
 error:
-  closesocket(socket);
+  CloseHandle(afd_helper_handle);
   return_map_error(-1);
 }
 
-int afd_poll(SOCKET driver_socket,
+int afd_poll(HANDLE afd_helper_handle,
              AFD_POLL_INFO* poll_info,
              OVERLAPPED* overlapped) {
   IO_STATUS_BLOCK* iosb;
@@ -147,7 +77,7 @@ int afd_poll(SOCKET driver_socket,
   }
 
   iosb->Status = STATUS_PENDING;
-  status = NtDeviceIoControlFile((HANDLE) driver_socket,
+  status = NtDeviceIoControlFile(afd_helper_handle,
                                  event,
                                  NULL,
                                  apc_context,

src/afd.h

@@ -31,12 +31,10 @@ typedef struct _AFD_POLL_INFO {
   AFD_POLL_HANDLE_INFO Handles[1];
 } AFD_POLL_INFO, *PAFD_POLL_INFO;
 
-WEPOLL_INTERNAL int afd_global_init(void);
+WEPOLL_INTERNAL int afd_create_helper_handle(HANDLE iocp,
+                                             HANDLE* afd_helper_handle_out);
 
-WEPOLL_INTERNAL int afd_create_driver_socket(HANDLE iocp,
-                                             SOCKET* driver_socket_out);
-
-WEPOLL_INTERNAL int afd_poll(SOCKET driver_socket,
+WEPOLL_INTERNAL int afd_poll(HANDLE afd_helper_handle,
                              AFD_POLL_INFO* poll_info,
                              OVERLAPPED* overlapped);
 

src/init.c

@@ -19,7 +19,7 @@ static BOOL CALLBACK init__once_callback(INIT_ONCE* once,
   unused_var(context);
 
   /* N.b. that initialization order matters here. */
-  if (ws_global_init() < 0 || nt_global_init() < 0 || afd_global_init() < 0 ||
+  if (ws_global_init() < 0 || nt_global_init() < 0 ||
       reflock_global_init() < 0 || epoll_global_init() < 0)
     return FALSE;
 

src/nt.h

@@ -40,6 +40,9 @@ typedef struct _LSA_UNICODE_STRING {
   PWSTR Buffer;
 } LSA_UNICODE_STRING, *PLSA_UNICODE_STRING, UNICODE_STRING, *PUNICODE_STRING;
 
+#define RTL_CONSTANT_STRING(s) \
+  { sizeof(s) - sizeof((s)[0]), sizeof(s), s }
+
 typedef struct _OBJECT_ATTRIBUTES {
   ULONG Length;
   HANDLE RootDirectory;
@@ -49,7 +52,29 @@ typedef struct _OBJECT_ATTRIBUTES {
   PVOID SecurityQualityOfService;
 } OBJECT_ATTRIBUTES, *POBJECT_ATTRIBUTES;
 
+#define RTL_CONSTANT_OBJECT_ATTRIBUTES(ObjectName, Attributes) \
+  { sizeof(OBJECT_ATTRIBUTES), NULL, ObjectName, Attributes, NULL, NULL }
+
+#ifndef FILE_OPEN
+#define FILE_OPEN 0x00000001UL
+#endif
+
 #define NT_NTDLL_IMPORT_LIST(X)                                              \
+  X(NTSTATUS,                                                                \
+    NTAPI,                                                                   \
+    NtCreateFile,                                                            \
+    (PHANDLE FileHandle,                                                     \
+     ACCESS_MASK DesiredAccess,                                              \
+     POBJECT_ATTRIBUTES ObjectAttributes,                                    \
+     PIO_STATUS_BLOCK IoStatusBlock,                                         \
+     PLARGE_INTEGER AllocationSize,                                          \
+     ULONG FileAttributes,                                                   \
+     ULONG ShareAccess,                                                      \
+     ULONG CreateDisposition,                                                \
+     ULONG CreateOptions,                                                    \
+     PVOID EaBuffer,                                                         \
+     ULONG EaLength))                                                        \
+                                                                             \
   X(NTSTATUS,                                                                \
     NTAPI,                                                                   \
     NtDeviceIoControlFile,                                                   \

src/poll-group.c

@@ -13,7 +13,7 @@ static const size_t POLL_GROUP__MAX_GROUP_SIZE = 32;
 typedef struct poll_group {
   port_state_t* port_state;
   queue_node_t queue_node;
-  SOCKET socket;
+  HANDLE afd_helper_handle;
   size_t group_size;
 } poll_group_t;
 
@@ -27,7 +27,8 @@ static poll_group_t* poll_group__new(port_state_t* port_state) {
   queue_node_init(&poll_group->queue_node);
   poll_group->port_state = port_state;
 
-  if (afd_create_driver_socket(port_state->iocp, &poll_group->socket) < 0) {
+  if (afd_create_helper_handle(port_state->iocp,
+                               &poll_group->afd_helper_handle) < 0) {
     free(poll_group);
     return NULL;
   }
@@ -39,7 +40,7 @@ static poll_group_t* poll_group__new(port_state_t* port_state) {
 
 void poll_group_delete(poll_group_t* poll_group) {
   assert(poll_group->group_size == 0);
-  closesocket(poll_group->socket);
+  CloseHandle(poll_group->afd_helper_handle);
   queue_remove(&poll_group->queue_node);
   free(poll_group);
 }
@@ -48,8 +49,8 @@ poll_group_t* poll_group_from_queue_node(queue_node_t* queue_node) {
   return container_of(queue_node, poll_group_t, queue_node);
 }
 
-SOCKET poll_group_get_socket(poll_group_t* poll_group) {
-  return poll_group->socket;
+HANDLE poll_group_get_afd_helper_handle(poll_group_t* poll_group) {
+  return poll_group->afd_helper_handle;
 }
 
 poll_group_t* poll_group_acquire(port_state_t* port_state) {

src/poll-group.h

@@ -16,6 +16,7 @@ WEPOLL_INTERNAL void poll_group_delete(poll_group_t* poll_group);
 
 WEPOLL_INTERNAL poll_group_t* poll_group_from_queue_node(
     queue_node_t* queue_node);
-WEPOLL_INTERNAL SOCKET poll_group_get_socket(poll_group_t* poll_group);
+WEPOLL_INTERNAL HANDLE
+    poll_group_get_afd_helper_handle(poll_group_t* poll_group);
 
 #endif /* WEPOLL_POLL_GROUP_H_ */

src/sock.c

@@ -47,13 +47,13 @@ static inline void sock__free(sock_state_t* sock_state) {
 }
 
 static int sock__cancel_poll(sock_state_t* sock_state) {
-  HANDLE driver_handle =
-      (HANDLE)(uintptr_t) poll_group_get_socket(sock_state->poll_group);
+  HANDLE afd_helper_handle =
+      poll_group_get_afd_helper_handle(sock_state->poll_group);
   assert(sock_state->poll_status == SOCK__POLL_PENDING);
 
   /* CancelIoEx() may fail with ERROR_NOT_FOUND if the overlapped operation has
    * already completed. This is not a problem and we proceed normally. */
-  if (!CancelIoEx(driver_handle, &sock_state->overlapped) &&
+  if (!CancelIoEx(afd_helper_handle, &sock_state->overlapped) &&
       GetLastError() != ERROR_NOT_FOUND)
     return_map_error(-1);
 
@@ -232,7 +232,7 @@ int sock_update(port_state_t* port_state, sock_state_t* sock_state) {
 
     memset(&sock_state->overlapped, 0, sizeof sock_state->overlapped);
 
-    if (afd_poll(poll_group_get_socket(sock_state->poll_group),
+    if (afd_poll(poll_group_get_afd_helper_handle(sock_state->poll_group),
                  &sock_state->poll_info,
                  &sock_state->overlapped) < 0) {
       switch (GetLastError()) {

src/ws.c

@@ -10,8 +10,6 @@
 #define SIO_BASE_HANDLE 0x48000022
 #endif
 
-#define WS__INITIAL_CATALOG_BUFFER_SIZE 0x4000 /* 16kb. */
-
 int ws_global_init(void) {
   int r;
   WSADATA wsa_data;
@@ -40,30 +38,3 @@ SOCKET ws_get_base_socket(SOCKET socket) {
 
   return base_socket;
 }
-
-/* Retrieves a copy of the winsock catalog.
- * The infos pointer must be released by the caller with free(). */
-int ws_get_protocol_catalog(WSAPROTOCOL_INFOW** infos_out,
-                            size_t* infos_count_out) {
-  DWORD buffer_size = WS__INITIAL_CATALOG_BUFFER_SIZE;
-  int count;
-  WSAPROTOCOL_INFOW* infos;
-
-retry:
-  infos = malloc(buffer_size);
-  if (infos == NULL)
-    return_set_error(-1, ERROR_NOT_ENOUGH_MEMORY);
-
-  count = WSAEnumProtocolsW(NULL, infos, &buffer_size);
-  if (count == SOCKET_ERROR) {
-    free(infos);
-    if (WSAGetLastError() == WSAENOBUFS)
-      goto retry; /* Try again with bigger buffer size. */
-    else
-      return_map_error(-1);
-  }
-
-  *infos_out = infos;
-  *infos_count_out = (size_t) count;
-  return 0;
-}

src/ws.h

@@ -6,9 +6,6 @@
 #include "win.h"
 
 WEPOLL_INTERNAL int ws_global_init(void);
-
 WEPOLL_INTERNAL SOCKET ws_get_base_socket(SOCKET socket);
-WEPOLL_INTERNAL int ws_get_protocol_catalog(WSAPROTOCOL_INFOW** infos_out,
-                                            size_t* infos_count_out);
 
 #endif /* WEPOLL_WS_H_ */