#ifndef _NTIOAPI_H

// Win32 FILE_REMOTE_PROTOCOL_INFO
typedef struct _FILE_REMOTE_PROTOCOL_INFORMATION
{
    // Structure Version
    USHORT StructureVersion;     // 1 for Win7, 2 for Win8 SMB3, 3 for Blue SMB3, 4 for RS5
    USHORT StructureSize;        // sizeof(FILE_REMOTE_PROTOCOL_INFORMATION)

    ULONG Protocol;             // Protocol (WNNC_NET_*) defined in winnetwk.h or ntifs.h.

    // Protocol Version & Type
    USHORT ProtocolMajorVersion;
    USHORT ProtocolMinorVersion;
    USHORT ProtocolRevision;

    USHORT Reserved;

    // Protocol-Generic Information
    ULONG Flags;

    struct
    {
        ULONG Reserved[8];
    } GenericReserved;

    // Protocol specific information

    union
    {
        struct
        {
            struct
            {
                ULONG Capabilities;
            } Server;
            struct
            {
                ULONG Capabilities;
                ULONG ShareFlags; // previoulsly CachingFlags before 21H1
                UCHAR ShareType; // RS5
                UCHAR Reserved0[3];
                ULONG Reserved1;
            } Share;
        } Smb2;
        ULONG Reserved[16];
    } ProtocolSpecific;
} FILE_REMOTE_PROTOCOL_INFORMATION, *PFILE_REMOTE_PROTOCOL_INFORMATION;

#endif
View code on GitHub

// ntifs.h

typedef struct _FILE_REMOTE_PROTOCOL_INFORMATION {
  USHORT StructureVersion;
  USHORT StructureSize;
  ULONG  Protocol;
  USHORT ProtocolMajorVersion;
  USHORT ProtocolMinorVersion;
  USHORT ProtocolRevision;
  USHORT Reserved;
  ULONG  Flags;
  struct {
    ULONG Reserved[8];
  } GenericReserved;
  struct {
    ULONG Reserved[16];
  } ProtocolSpecificReserved;
  union {
    struct {
      struct {
        ULONG Capabilities;
      } Server;
      struct {
        ULONG Capabilities;
        ULONG ShareFlags;
        ULONG CachingFlags;
        UCHAR ShareType;
        UCHAR Reserved0[3];
        ULONG Reserved1;
      } Share;
    } Smb2;
    ULONG Reserved[16];
  } ProtocolSpecific;
} FILE_REMOTE_PROTOCOL_INFORMATION, *PFILE_REMOTE_PROTOCOL_INFORMATION;
View the official Windows Driver Kit DDI reference