source/include/byteorder.h

   1 /*
   2    Unix SMB/Netbios implementation.
   3    Version 1.9.
   4    SMB Byte handling
   5    Copyright (C) Andrew Tridgell 1992-1997
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 2 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program; if not, write to the Free Software
  19    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20 */
  21
  22 /*
  23    This file implements macros for machine independent short and
  24    int manipulation
  25
  26 Here is a description of this file that I emailed to the samba list once:
  27
  28 > I am confused about the way that byteorder.h works in Samba. I have
  29 > looked at it, and I would have thought that you might make a distinction
  30 > between LE and BE machines, but you only seem to distinguish between 386
  31 > and all other architectures.
  32 >
  33 > Can you give me a clue?
  34
  35 sure.
  36
  37 The distinction between 386 and other architectures is only there as
  38 an optimisation. You can take it out completely and it will make no
  39 difference. The routines (macros) in byteorder.h are totally byteorder
  40 independent. The 386 optimsation just takes advantage of the fact that
  41 the x86 processors don't care about alignment, so we don't have to
  42 align ints on int boundaries etc. If there are other processors out
  43 there that aren't alignment sensitive then you could also define
  44 CAREFUL_ALIGNMENT=0 on those processors as well.
  45
  46 Ok, now to the macros themselves. I'll take a simple example, say we
  47 want to extract a 2 byte integer from a SMB packet and put it into a
  48 type called uint16 that is in the local machines byte order, and you
  49 want to do it with only the assumption that uint16 is _at_least_ 16
  50 bits long (this last condition is very important for architectures
  51 that don't have any int types that are 2 bytes long)
  52
  53 You do this:
  54
  55 #define CVAL(buf,pos) (((unsigned char *)(buf))[pos])
  56 #define PVAL(buf,pos) ((unsigned)CVAL(buf,pos))
  57 #define SVAL(buf,pos) (PVAL(buf,pos)|PVAL(buf,(pos)+1)<<8)
  58
  59 then to extract a uint16 value at offset 25 in a buffer you do this:
  60
  61 char *buffer = foo_bar();
  62 uint16 xx = SVAL(buffer,25);
  63
  64 We are using the byteoder independence of the ANSI C bitshifts to do
  65 the work. A good optimising compiler should turn this into efficient
  66 code, especially if it happens to have the right byteorder :-)
  67
  68 I know these macros can be made a bit tidier by removing some of the
  69 casts, but you need to look at byteorder.h as a whole to see the
  70 reasoning behind them. byteorder.h defines the following macros:
  71
  72 SVAL(buf,pos) - extract a 2 byte SMB value
  73 IVAL(buf,pos) - extract a 4 byte SMB value
  74 SVALS(buf,pos) signed version of SVAL()
  75 IVALS(buf,pos) signed version of IVAL()
  76
  77 SSVAL(buf,pos,val) - put a 2 byte SMB value into a buffer
  78 SIVAL(buf,pos,val) - put a 4 byte SMB value into a buffer
  79 SSVALS(buf,pos,val) - signed version of SSVAL()
  80 SIVALS(buf,pos,val) - signed version of SIVAL()
  81
  82 RSVAL(buf,pos) - like SVAL() but for NMB byte ordering
  83 RIVAL(buf,pos) - like IVAL() but for NMB byte ordering
  84 RSSVAL(buf,pos,val) - like SSVAL() but for NMB ordering
  85 RSIVAL(buf,pos,val) - like SIVAL() but for NMB ordering
  86
  87 it also defines lots of intermediate macros, just ignore those :-)
  88
  89 */
  90
  91 /* some switch macros that do both store and read to and from SMB buffers */
  92
  93 #define RW_PCVAL(read,inbuf,outbuf,len) \
  94                 if (read) { PCVAL (inbuf,0,outbuf,len) } \
  95                 else      { PSCVAL(inbuf,0,outbuf,len) }
  96
  97 #define RW_PIVAL(read,inbuf,outbuf,len) \
  98                 if (read) { PIVAL (inbuf,0,outbuf,len) } \
  99                 else      { PSIVAL(inbuf,0,outbuf,len) }
 100
 101 #define RW_PSVAL(read,inbuf,outbuf,len) \
 102                 if (read) { PSVAL (inbuf,0,outbuf,len) } \
 103                 else      { PSSVAL(inbuf,0,outbuf,len) }
 104
 105 #define RW_CVAL(read, inbuf, outbuf, offset) \
 106                 if (read) (outbuf) = CVAL (inbuf,offset); \
 107                 else                 SCVAL(inbuf,offset,outbuf);
 108
 109 #define RW_IVAL(read, inbuf, outbuf, offset) \
 110                 if (read) (outbuf)= IVAL (inbuf,offset); \
 111                 else                SIVAL(inbuf,offset,outbuf);
 112
 113 #define RW_SVAL(read, inbuf, outbuf, offset) \
 114                 if (read) (outbuf)= SVAL (inbuf,offset); \
 115                 else                SSVAL(inbuf,offset,outbuf);
 116
 117 #undef CAREFUL_ALIGNMENT
 118
 119 /* we know that the 386 can handle misalignment and has the "right"
 120    byteorder */
 121 #ifdef __i386__
 122 #define CAREFUL_ALIGNMENT 0
 123 #endif
 124
 125 #ifndef CAREFUL_ALIGNMENT
 126 #define CAREFUL_ALIGNMENT 1
 127 #endif
 128
 129 #define CVAL(buf,pos) (((unsigned char *)(buf))[pos])
 130 #define PVAL(buf,pos) ((unsigned)CVAL(buf,pos))
 131 #define SCVAL(buf,pos,val) (CVAL(buf,pos) = (val))
 132
 133
 134 #if CAREFUL_ALIGNMENT
 135
 136 #define SVAL(buf,pos) (PVAL(buf,pos)|PVAL(buf,(pos)+1)<<8)
 137 #define IVAL(buf,pos) (SVAL(buf,pos)|SVAL(buf,(pos)+2)<<16)
 138 #define SSVALX(buf,pos,val) (CVAL(buf,pos)=(val)&0xFF,CVAL(buf,pos+1)=(val)>>8)
 139 #define SIVALX(buf,pos,val) (SSVALX(buf,pos,val&0xFFFF),SSVALX(buf,pos+2,val>>16))
 140 #define SVALS(buf,pos) ((int16)SVAL(buf,pos))
 141 #define IVALS(buf,pos) ((int32)IVAL(buf,pos))
 142 #define SSVAL(buf,pos,val) SSVALX((buf),(pos),((uint16)(val)))
 143 #define SIVAL(buf,pos,val) SIVALX((buf),(pos),((uint32)(val)))
 144 #define SSVALS(buf,pos,val) SSVALX((buf),(pos),((int16)(val)))
 145 #define SIVALS(buf,pos,val) SIVALX((buf),(pos),((int32)(val)))
 146
 147 #else
 148
 149 /* this handles things for architectures like the 386 that can handle
 150    alignment errors */
 151 /*
 152    WARNING: This section is dependent on the length of int16 and int32
 153    being correct
 154 */
 155
 156 /* get single value from an SMB buffer */
 157 #define SVAL(buf,pos) (*(uint16 *)((char *)(buf) + (pos)))
 158 #define IVAL(buf,pos) (*(uint32 *)((char *)(buf) + (pos)))
 159 #define SVALS(buf,pos) (*(int16 *)((char *)(buf) + (pos)))
 160 #define IVALS(buf,pos) (*(int32 *)((char *)(buf) + (pos)))
 161
 162 /* store single value in an SMB buffer */
 163 #define SSVAL(buf,pos,val) SVAL(buf,pos)=((uint16)(val))
 164 #define SIVAL(buf,pos,val) IVAL(buf,pos)=((uint32)(val))
 165 #define SSVALS(buf,pos,val) SVALS(buf,pos)=((int16)(val))
 166 #define SIVALS(buf,pos,val) IVALS(buf,pos)=((int32)(val))
 167
 168 #endif
 169
 170
 171 /* macros for reading / writing arrays */
 172
 173 #define SMBMACRO(macro,buf,pos,val,len,size) \
 174 { int l; for (l = 0; l < (len); l++) (val)[l] = macro((buf), (pos) + (size)*l); }
 175
 176 #define SSMBMACRO(macro,buf,pos,val,len,size) \
 177 { int l; for (l = 0; l < (len); l++) macro((buf), (pos) + (size)*l, (val)[l]); }
 178
 179 /* reads multiple data from an SMB buffer */
 180 #define PCVAL(buf,pos,val,len) SMBMACRO(CVAL,buf,pos,val,len,1)
 181 #define PSVAL(buf,pos,val,len) SMBMACRO(SVAL,buf,pos,val,len,2)
 182 #define PIVAL(buf,pos,val,len) SMBMACRO(IVAL,buf,pos,val,len,4)
 183 #define PCVALS(buf,pos,val,len) SMBMACRO(CVALS,buf,pos,val,len,1)
 184 #define PSVALS(buf,pos,val,len) SMBMACRO(SVALS,buf,pos,val,len,2)
 185 #define PIVALS(buf,pos,val,len) SMBMACRO(IVALS,buf,pos,val,len,4)
 186
 187 /* stores multiple data in an SMB buffer */
 188 #define PSCVAL(buf,pos,val,len) SSMBMACRO(SCVAL,buf,pos,val,len,1)
 189 #define PSSVAL(buf,pos,val,len) SSMBMACRO(SSVAL,buf,pos,val,len,2)
 190 #define PSIVAL(buf,pos,val,len) SSMBMACRO(SIVAL,buf,pos,val,len,4)
 191 #define PSCVALS(buf,pos,val,len) SSMBMACRO(SCVALS,buf,pos,val,len,1)
 192 #define PSSVALS(buf,pos,val,len) SSMBMACRO(SSVALS,buf,pos,val,len,2)
 193 #define PSIVALS(buf,pos,val,len) SSMBMACRO(SIVALS,buf,pos,val,len,4)
 194
 195
 196 /* now the reverse routines - these are used in nmb packets (mostly) */
 197 #define SREV(x) ((((x)&0xFF)<<8) | (((x)>>8)&0xFF))
 198 #define IREV(x) ((SREV(x)<<16) | (SREV((x)>>16)))
 199
 200 #define RSVAL(buf,pos) SREV(SVAL(buf,pos))
 201 #define RIVAL(buf,pos) IREV(IVAL(buf,pos))
 202 #define RSSVAL(buf,pos,val) SSVAL(buf,pos,SREV(val))
 203 #define RSIVAL(buf,pos,val) SIVAL(buf,pos,IREV(val))
 204
 205 #define DBG_RW_PCVAL(charmode,string,depth,base,read,inbuf,outbuf,len) \
 206         RW_PCVAL(read,inbuf,outbuf,len) \
 207         DEBUG(5,("%s%04x %s: ", \
 208              tab_depth(depth), PTR_DIFF(inbuf,base),string)); \
 209     if (charmode) print_asc(5, (char*)(outbuf), (len)); else \
 210         { int idx; for (idx = 0; idx < len; idx++) { DEBUG(5,("%02x ", CVAL(&((outbuf)[idx]), 0))); } } \
 211         DEBUG(5,("\n"));
 212
 213 #define DBG_RW_PSVAL(charmode,string,depth,base,read,inbuf,outbuf,len) \
 214         RW_PSVAL(read,inbuf,outbuf,len) \
 215         DEBUG(5,("%s%04x %s: ", \
 216              tab_depth(depth), PTR_DIFF(inbuf,base),string)); \
 217     if (charmode) print_asc(5, (char*)(outbuf), 2*(len)); else \
 218         { int idx; for (idx = 0; idx < len; idx++) { DEBUG(5,("%04x ", SVAL(&((outbuf)[idx]), 0))); } } \
 219         DEBUG(5,("\n"));
 220
 221 #define DBG_RW_PIVAL(charmode,string,depth,base,read,inbuf,outbuf,len) \
 222         RW_PIVAL(read,inbuf,outbuf,len) \
 223         DEBUG(5,("%s%04x %s: ", \
 224              tab_depth(depth), PTR_DIFF(inbuf,base),string)); \
 225     if (charmode) print_asc(5, (char*)(outbuf), 4*(len)); else \
 226         { int idx; for (idx = 0; idx < len; idx++) { DEBUG(5,("%08x ", IVAL(&((outbuf)[idx]), 0))); } } \
 227         DEBUG(5,("\n"));
 228
 229 #define DBG_RW_CVAL(string,depth,base,read,inbuf,outbuf) \
 230         RW_CVAL(read,inbuf,outbuf,0) \
 231         DEBUG(5,("%s%04x %s: %02x\n", \
 232              tab_depth(depth), PTR_DIFF(inbuf,base), string, outbuf));
 233
 234 #define DBG_RW_SVAL(string,depth,base,read,inbuf,outbuf) \
 235         RW_SVAL(read,inbuf,outbuf,0) \
 236         DEBUG(5,("%s%04x %s: %04x\n", \
 237              tab_depth(depth), PTR_DIFF(inbuf,base), string, outbuf));
 238
 239 #define DBG_RW_IVAL(string,depth,base,read,inbuf,outbuf) \
 240         RW_IVAL(read,inbuf,outbuf,0) \
 241         DEBUG(5,("%s%04x %s: %08x\n", \
 242              tab_depth(depth), PTR_DIFF(inbuf,base), string, outbuf));
 243