107 lines
2.8 KiB
C
107 lines
2.8 KiB
C
/*++
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Copyright (c) 1997, Microsoft Corporation
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Module Name:
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edithlp.h
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Abstract:
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This module contains helper-declarations for the NAT's built-in editors.
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Author:
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Abolade Gbadegesin (t-abolag) 25-Aug-1997
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Revision History:
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--*/
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#ifndef _NAT_EDITHLP_H_
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#define _NAT_EDITHLP_H_
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//
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// Macro: COPY_FROM_BUFFER
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//
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// This macro copies from a buffer-chain to a flat buffer.
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//
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#define \
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COPY_FROM_BUFFER( \
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Destination, \
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Source, \
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Length, \
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Offset \
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) \
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{ \
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PUCHAR _Destination = Destination; \
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ULONG _Length = Length; \
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LONG _Offset = Offset; \
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IPRcvBuf* _Source = Source; \
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while ((LONG)_Source->ipr_size < _Offset) { \
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_Offset -= _Source->ipr_size; \
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_Source = _Source->ipr_next; \
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} \
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while (_Length) { \
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ULONG Bytes = min(_Length, _Source->ipr_size-_Offset); \
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RtlCopyMemory(_Destination, _Source->ipr_buffer+_Offset, Bytes);\
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_Length -= Bytes; \
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_Destination += Bytes; \
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_Source = _Source->ipr_next; \
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_Offset = 0; \
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} \
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}
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//
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// Macro: FIND_HEADER_FIELD
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//
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// This macro initializes a pseudo header's 'Field' member with the address
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// in a buffer chain of the corresponding application-header field.
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// It is assumed that each field of the application-header is aligned
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// on the natural boundary for its width (e.g. 32-bit fields aligned
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// on 32-bit boundaries).
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//
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// 'RecvBuffer' gives the first buffer in the chain containing the field,
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// and 'DataOffsetp' points to the (negative) offset into 'RecvBuffer'
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// of the header. This offset would be negative if the header is spread
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// over multiple buffers and 'RecvBuffer' is one of the later buffers.
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//
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// The macro advances through the buffer chain until it finds the buffer
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// containing the field (using FIELD_OFFSET). It then initializes the
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// pseudo-header's field pointer with the position of the field
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// (i.e. 'Header->Field = &(field in buffer-chain)).
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//
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// Given that it walks the buffer chain, the macro thus requires that
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// the pseudo-header's field pointers be initialized in-order,
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// since an earlier field cannot be found in the chain after we have
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// passed the buffer containing the latter while searching for a later field.
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//
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#define \
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FIND_HEADER_FIELD( \
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RecvBuffer, \
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DataOffsetp, \
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Header, \
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Field, \
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HeaderType, \
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FieldType \
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) \
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while ((LONG)(RecvBuffer)->ipr_size < \
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*(DataOffsetp) + FIELD_OFFSET(HeaderType, Field) \
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) { \
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*(DataOffsetp) -= (RecvBuffer)->ipr_size; \
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(RecvBuffer) = (RecvBuffer)->ipr_next; \
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if (!(RecvBuffer)) { break; } \
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} \
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if (RecvBuffer) { \
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(Header)->Field = \
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(FieldType)((RecvBuffer)->ipr_buffer + *(DataOffsetp) + \
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FIELD_OFFSET(HeaderType, Field)); \
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}
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#endif // _NAT_EDITHLP_H_
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