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213 lines
8.3 KiB
Plaintext
213 lines
8.3 KiB
Plaintext
internals.txt, 8 May 1996
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Written by David Chappell <David.Chappell@mail.trincoll.edu>.
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This document describes some of the internal functions which must be
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understood by anyone wishing to add features to Samba.
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=============================================================================
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This section describes the macros defined in byteorder.h. These macros
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are used extensively in the Samba code.
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-----------------------------------------------------------------------------
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CVAL(buf,pos)
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returns the byte at offset pos within buffer buf as an unsigned character.
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-----------------------------------------------------------------------------
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PVAL(buf,pos)
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returns the value of CVAL(buf,pos) cast to type unsigned integer.
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-----------------------------------------------------------------------------
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SCVAL(buf,pos,val)
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sets the byte at offset pos within buffer buf to value val.
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-----------------------------------------------------------------------------
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SVAL(buf,pos)
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returns the value of the unsigned short (16 bit) little-endian integer at
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offset pos within buffer buf. An integer of this type is sometimes
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refered to as "USHORT".
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-----------------------------------------------------------------------------
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IVAL(buf,pos)
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returns the value of the unsigned 32 bit little-endian integer at offset
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pos within buffer buf.
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-----------------------------------------------------------------------------
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SVALS(buf,pos)
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returns the value of the signed short (16 bit) little-endian integer at
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offset pos within buffer buf.
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-----------------------------------------------------------------------------
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IVALS(buf,pos)
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returns the value of the signed 32 bit little-endian integer at offset pos
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within buffer buf.
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-----------------------------------------------------------------------------
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SSVAL(buf,pos,val)
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sets the unsigned short (16 bit) little-endian integer at offset pos within
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buffer buf to value val.
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-----------------------------------------------------------------------------
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SIVAL(buf,pos,val)
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sets the unsigned 32 bit little-endian integer at offset pos within buffer
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buf to the value val.
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-----------------------------------------------------------------------------
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SSVALS(buf,pos,val)
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sets the short (16 bit) signed little-endian integer at offset pos within
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buffer buf to the value val.
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-----------------------------------------------------------------------------
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SIVALS(buf,pos,val)
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sets the signed 32 bit little-endian integer at offset pos withing buffer
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buf to the value val.
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-----------------------------------------------------------------------------
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RSVAL(buf,pos)
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returns the value of the unsigned short (16 bit) big-endian integer at
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offset pos within buffer buf.
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-----------------------------------------------------------------------------
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RIVAL(buf,pos)
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returns the value of the unsigned 32 bit big-endian integer at offset
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pos within buffer buf.
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-----------------------------------------------------------------------------
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RSSVAL(buf,pos,val)
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sets the value of the unsigned short (16 bit) big-endian integer at
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offset pos within buffer buf to value val.
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refered to as "USHORT".
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-----------------------------------------------------------------------------
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RSIVAL(buf,pos,val)
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sets the value of the unsigned 32 bit big-endian integer at offset
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pos within buffer buf to value val.
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=============================================================================
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This section describes the functions need to make a LAN Manager RPC call.
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This information had been obtained by examining the Samba code and the LAN
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Manager 2.0 API documentation. It should not be considered entirely
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reliable.
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-----------------------------------------------------------------------------
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call_api(int prcnt, int drcnt, int mprcnt, int mdrcnt,
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char *param, char *data, char **rparam, char **rdata);
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This function is defined in client.c. It uses an SMB transaction to call a
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remote api.
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The parameters are as follows:
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prcnt: the number of bytes of parameters begin sent.
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drcnt: the number of bytes of data begin sent.
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mprcnt: the maximum number of bytes of parameters which should be returned
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mdrcnt: the maximum number of bytes of data which should be returned
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param: a pointer to the parameters to be sent.
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data: a pointer to the data to be sent.
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rparam: a pointer to a pointer which will be set to point to the returned
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paramters. The caller of call_api() must deallocate this memory.
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rdata: a pointer to a pointer which will be set to point to the returned
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data. The caller of call_api() must deallocate this memory.
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-----------------------------------------------------------------------------
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These are the parameters which you ought to send, in the order of their
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appearance in the parameter block:
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* An unsigned 16 bit integer API number. You should set this value with
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SSVAL(). I do not know where these numbers are described.
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* An ASCIIZ string describing the parameters to the API function as defined
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in the LAN Manager documentation. The first parameter, which is the server
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name, is omitted. This string is based uppon the API function as described
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in the manual, not the data which is actually passed.
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* An ASCIIZ string describing the data structure which ought to be returned.
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* Any parameters which appear in the function call, as defined in the LAN
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Manager API documentation, after the "Server" and up to and including the
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"uLevel" parameters.
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* An unsigned 16 bit integer which gives the size in bytes of the buffer we
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will use to receive the returned array of data structures. Presumably this
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should be the same as mdrcnt. This value should be set with SSVAL().
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* An ASCIIZ string describing substructures which should be returned. If no
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substructures apply, this string is of zero length.
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-----------------------------------------------------------------------------
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The code in client.c always calls call_api() with no data. It is unclear
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when a non-zero length data buffer would be sent.
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-----------------------------------------------------------------------------
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The returned parameters (pointed to by rparam), in their order of appearance
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are:
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* An unsigned 16 bit integer which contains the API function's return code.
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This value should be read with SVAL().
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* An adjustment which tells the amount by which pointers in the returned
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data should be adjusted. This value should be read with SVAL(). Basically,
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the address of the start of the returned data buffer should have the returned
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pointer value added to it and then have this value subtracted from it in
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order to obtain the currect offset into the returned data buffer.
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* A count of the number of elements in the array of structures returned.
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It is also possible that this may sometimes be the number of bytes returned.
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-----------------------------------------------------------------------------
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When call_api() returns, rparam points to the returned parameters. The
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first if these is the result code. It will be zero if the API call
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suceeded. This value by be read with "SVAL(rparam,0)".
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The second parameter may be read as "SVAL(rparam,2)". It is a 16 bit offset
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which indicates what the base address of the returned data buffer was when
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it was built on the server. It should be used to correct pointer before
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use.
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The returned data buffer contains the array of returned data structures.
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Note that all pointers must be adjusted before use. The function
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fix_char_ptr() in client.c can be used for this purpose.
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The third parameter (which may be read as "SVAL(rparam,4)") has something to
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do with indicating the amount of data returned or possibly the amount of
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data which can be returned if enough buffer space is allowed.
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-----------------------------------------------------------------------------
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Certain data structures are described by means of ASCIIz strings containing
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code characters. These are the code characters:
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W a type byte little-endian unsigned integer
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N a count of substructures which follow
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D a four byte little-endian unsigned integer
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B a byte (with optional count expressed as trailing ASCII digits)
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z a four byte offset to a NULL terminated string
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l a four byte offset to non-string user data
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b an offset to data (with count expressed as trailing ASCII digits)
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r pointer to returned data buffer???
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L length in bytes of returned data buffer???
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h number of bytes of information available???
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----------------------------------------------------------------------------
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