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wireshark/epan/wslua/wslua_struct.c

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/******************************************************************************
* Copyright (C) 2010-2012 Lua.org, PUC-Rio. All rights reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
******************************************************************************/
/*
** {======================================================
** Library for packing/unpacking structures.
** $Id: struct.c,v 1.4 2012/07/04 18:54:29 roberto Exp $
** See Copyright Notice above.
**
** Small changes were made by Hadriel Kaplan - those changes
** are in the Public Domain.
**
** Some changes are based on a patch to struct.h from
** Flemming Madsen, from here:
** http://lua-users.org/lists/lua-l/2009-10/msg00572.html
** In particular, these changes from him:
** -Can handle 'long long' integers (i8 / I8); though they're converted to doubles
** -Can insert/specify padding anywhere in a struct. ('X' eg. when a string is following a union)
** -Can report current offset in both pack and unpack ('=')
** -Can mask out return values when you only want to calculate sizes or unmarshal pascal-style strings. '(' & ')'
**
** Changes I made:
** -Added support for Int64/UIn64 being packed/unpacked, using 'e'/'E'
** -Made it follow Wireshark's conventions so we could get API docs
** =======================================================
*/
/*
** Valid formats:
** > - big endian
** < - little endian
** ![num] - alignment
** x[num] - pad num bytes, default 1
** X[num] - pad to num align, default MAXALIGN
**
** Following are system-dependent sizes:
** b/B - signed/unsigned byte
** h/H - signed/unsigned short
** i/I - signed/unsigned int
** l/L - signed/unsigned long
** f - float
** d - double
** T - size_t
**
** Following are system-independent sizes:
** in/In - signed/unsigned integer of size `n' bytes
Note: unpack of i/I is done to a Lua_number, typically a double,
so unpacking a 64-bit field (i8/I8) will lose precision.
Use e/E to unpack into a Wireshark Int64/UInt64 object/userdata instead.
** e/E - signed/unsigned eight-byte Integer (64bits, long long), to/from Int64/UInt64 object
** cn - sequence of `n' chars (from/to a string); when packing, n==0 means
the whole string; when unpacking, n==0 means use the previous
read number as the string length
** s - zero-terminated string
** ' ' - ignored
** '(' ')' - stop assigning items. ')' start assigning (padding when packing)
** '=' - return current position / offset
*/
#include <assert.h>
#include <ctype.h>
#include <limits.h>
#include <stddef.h>
#include <string.h>
#include <stdio.h>
#include "config.h"
#include "wslua.h"
/* WSLUA_MODULE Struct Binary encode/decode support */
/* TODO: figure out a way for wslua Module's to have (possibly long) description text */
/* The following line is here so that make-reg.pl does the right thing. This 'Struct' class
isn't really a class, so it doesn't have the checkStruct/pushStruct/etc. functions
the following macro would generate; but it does need to be registered and such.
WSLUA_CLASS_DEFINE_BASE(Struct,NOP,NOP,0);
*/
/* basic integer type - yes this is system-specific size - it's meant to be */
#if !defined(STRUCT_INT)
#define STRUCT_INT long
#endif
typedef STRUCT_INT Inttype;
/* corresponding unsigned version */
typedef unsigned STRUCT_INT Uinttype;
/* maximum size (in bytes) for integral types */
#define MAXINTSIZE 32
/* is 'x' a power of 2? */
#define isp2(x) ((x) > 0 && ((x) & ((x) - 1)) == 0)
/* dummy structure to get padding/alignment requirements */
struct cD {
gchar c;
gdouble d;
};
#define PADDING (sizeof(struct cD) - sizeof(gdouble))
#define MAXALIGN (PADDING > sizeof(int) ? PADDING : sizeof(int))
/* endian options */
#define BIG 0
#define LITTLE 1
/* trick to determine native endianess of system */
static union {
int dummy;
gchar endian;
} const native = {1};
/* settings info */
typedef struct Header {
int endian;
int align;
gboolean noassign;
} Header;
/* For options that take a number argument, gets the number */
static int getnum (const gchar **fmt, int df) {
if (!isdigit(**fmt)) /* no number? */
return df; /* return default value */
else {
int a = 0;
do {
a = a*10 + *((*fmt)++) - '0';
} while (isdigit(**fmt));
return a;
}
}
#define defaultoptions(h) ((h)->endian = native.endian, (h)->align = 1, (h)->noassign = FALSE)
/* gets size (number of bytes) for a given type */
static size_t optsize (lua_State *L, gchar opt, const gchar **fmt) {
switch (opt) {
case 'B': case 'b': return sizeof(gchar);
case 'H': case 'h': return sizeof(gshort);
case 'L': case 'l': return sizeof(glong);
case 'E': case 'e': return sizeof(gint64);
case 'T': return sizeof(size_t);
case 'f': return sizeof(gfloat);
case 'd': return sizeof(gdouble);
case 'x': return getnum(fmt, 1);
case 'X': return getnum(fmt, MAXALIGN);
case 'c': return getnum(fmt, 1);
case 'i': case 'I': {
int sz = getnum(fmt, sizeof(int));
if (sz > MAXINTSIZE)
luaL_error(L, "integral size %d is larger than limit of %d",
sz, MAXINTSIZE);
return sz;
}
case 's': case ' ':
case '<': case '>':
case '(': case ')':
case '!': case '=':
return 0; /* these cases do not have a size */
default: {
const gchar *msg = lua_pushfstring(L, "invalid format option [%c]", opt);
return luaL_argerror(L, 1, msg);
}
}
}
/*
** return number of bytes needed to align an element of size 'size'
** at current position 'len'
*/
static int gettoalign (size_t len, Header *h, int opt, size_t size) {
if (size == 0 || opt == 'c' || opt == 's') return 0;
if (size > (size_t)h->align)
size = h->align; /* respect max. alignment */
return (int)((size - (len & (size - 1))) & (size - 1));
}
/*
** options to control endianess and alignment settings
*/
static void controloptions (lua_State *L, int opt, const gchar **fmt,
Header *h) {
switch (opt) {
case ' ': return; /* ignore white spaces */
case '>': h->endian = BIG; return;
case '<': h->endian = LITTLE; return;
case '(': h->noassign = TRUE; return;
case ')': h->noassign = FALSE; return;
case '!': {
int a = getnum(fmt, MAXALIGN);
if (!isp2(a))
luaL_error(L, "alignment %d is not a power of 2", a);
h->align = a;
return;
}
default: {
const char *msg = lua_pushfstring(L, "invalid format option '%c'", opt);
luaL_argerror(L, 1, msg);
}
}
}
/* Encodes a Lua number as an integer of given size and endiannes into a string struct */
static void putinteger (lua_State *L, luaL_Buffer *b, int arg, int endian,
int size) {
lua_Number n = luaL_checknumber(L, arg);
/* this one's not system dependent size - it's a long long */
gint64 value;
gchar buff[MAXINTSIZE];
if (n < 0)
value = (guint64)(gint64)n;
else
value = (guint64)n;
if (endian == LITTLE) {
int i;
for (i = 0; i < size; i++) {
buff[i] = (value & 0xff);
value >>= 8;
}
}
else {
int i;
for (i = size - 1; i >= 0; i--) {
buff[i] = (value & 0xff);
value >>= 8;
}
}
luaL_addlstring(b, buff, size);
}
/* corrects endiannes - usually done by other functions themselves, but is
* used for float/doubles, since on some platforms they're endian'ed as well
*/
static void correctbytes (gchar *b, int size, int endian) {
if (endian != native.endian) {
int i = 0;
while (i < --size) {
gchar temp = b[i];
b[i++] = b[size];
b[size] = temp;
}
}
}
WSLUA_CONSTRUCTOR Struct_pack (lua_State *L) {
/* Returns a string containing the values arg1, arg2, etc. packed/encoded according to the format string. */
#define WSLUA_ARG_Struct_pack_FORMAT 1 /* The format string */
#define WSLUA_ARG_Struct_pack_STRUCT 2 /* One or more Lua value(s) to encode, based on the given format. */
luaL_Buffer b;
const char *fmt = luaL_checkstring(L, WSLUA_ARG_Struct_pack_FORMAT);
Header h;
int poscnt = 0;
int posBuf[10];
int arg = 2;
size_t totalsize = 0;
defaultoptions(&h);
lua_pushnil(L); /* mark to separate arguments from string buffer */
luaL_buffinit(L, &b);
while (*fmt != '\0') {
int opt = *fmt++;
size_t size = optsize(L, opt, &fmt);
int toalign = gettoalign(totalsize, &h, opt, size);
totalsize += toalign;
while (toalign-- > 0) luaL_addchar(&b, '\0');
if (opt == 'X') size = 0; /* 'X' is about alignment, not size */
if (h.noassign && size) opt = 'x'; /* for pack, "(i4)" is the same as "x4" */
switch (opt) {
case 'b': case 'B': case 'h': case 'H':
case 'l': case 'L': case 'T': case 'i': case 'I': { /* integer types */
putinteger(L, &b, arg++, h.endian, (int)size);
break;
}
case 'e': {
Int64_pack(L, &b, arg++, h.endian == LITTLE);
break;
}
case 'E': {
UInt64_pack(L, &b, arg++, h.endian == LITTLE);
break;
}
case 'x': case 'X': {
size_t len = size;
while (len-- > 0)
luaL_addchar(&b, '\0');
break;
}
case 'f': {
gfloat f = (gfloat)luaL_checknumber(L, arg++);
correctbytes((gchar *)&f, (int)size, h.endian);
luaL_addlstring(&b, (gchar *)&f, size);
break;
}
case 'd': {
gdouble d = luaL_checknumber(L, arg++);
correctbytes((gchar *)&d, (int)size, h.endian);
luaL_addlstring(&b, (gchar *)&d, size);
break;
}
case 'c': case 's': {
size_t l;
const gchar *s = luaL_checklstring(L, arg++, &l);
if (size == 0) size = l;
luaL_argcheck(L, l >= (size_t)size, arg, "string too short");
luaL_addlstring(&b, s, size);
if (opt == 's') {
luaL_addchar(&b, '\0'); /* add zero at the end */
size++;
}
break;
}
case '=': {
if (poscnt < (int)(sizeof(posBuf)/sizeof(posBuf[0])))
posBuf[poscnt++] = (int)totalsize + 1;
break;
}
default: controloptions(L, opt, &fmt, &h);
}
totalsize += size;
}
luaL_pushresult(&b);
for (arg = 0; arg < poscnt; arg++)
lua_pushinteger(L, posBuf[arg]);
WSLUA_RETURN(poscnt + 1); /* The packed binary Lua string, plus any positions due to '=' being used in format. */
}
/* Decodes an integer from a string struct into a Lua number, based on
* given endianess and size. If the integer type is signed, this makes
* the Lua number be +/- correctly as well.
*/
static lua_Number getinteger (const gchar *buff, int endian,
int issigned, int size) {
Uinttype l = 0;
int i;
if (endian == BIG) {
for (i = 0; i < size; i++) {
l <<= 8;
l |= (Uinttype)(guchar)buff[i];
}
}
else {
for (i = size - 1; i >= 0; i--) {
l <<= 8;
l |= (Uinttype)(guchar)buff[i];
}
}
if (!issigned)
return (lua_Number)l;
else { /* signed format */
Uinttype mask = (Uinttype)(~((Uinttype)0)) << (size*8 - 1);
if (l & mask) /* negative value? */
l |= mask; /* signal extension */
return (lua_Number)(Inttype)l;
}
}
#define b_pushnumber(n) { if (!h.noassign) lua_pushnumber(L, (lua_Number)(n)); }
WSLUA_CONSTRUCTOR Struct_unpack (lua_State *L) {
/* Unpacks/decodes multiple Lua values from a given struct-like binary Lua string.
The number of returned values depends on the format given, plus an addtional value of the position where it stopped reading is returned. */
#define WSLUA_ARG_Struct_unpack_FORMAT 1 /* The format string */
#define WSLUA_ARG_Struct_unpack_STRUCT 2 /* The binary Lua string to unpack */
#define WSLUA_OPTARG_Struct_unpack_BEGIN 3 /* The position to begin reading from (default=1) */
Header h;
const char *fmt = luaL_checkstring(L, WSLUA_ARG_Struct_unpack_FORMAT);
size_t ld;
const char *data = luaL_checklstring(L, WSLUA_ARG_Struct_unpack_STRUCT, &ld);
size_t pos = luaL_optinteger(L, WSLUA_OPTARG_Struct_unpack_BEGIN, 1) - 1;
defaultoptions(&h);
lua_settop(L, 2);
while (*fmt) {
int opt = *fmt++;
size_t size = optsize(L, opt, &fmt);
pos += gettoalign(pos, &h, opt, size);
luaL_argcheck(L, pos+size <= ld, 2, "data string too short");
if (opt == 'X') size = 0;
if (h.noassign && size > 0) {
/* if we're not assigning, and the opt type has a size, then loop again */
/* this will not be the case for controloptions, 'c0', 's', and '=' */
pos += size;
continue;
}
luaL_checkstack(L, 1, "too many results");
switch (opt) {
case 'b': case 'B': case 'h': case 'H':
case 'l': case 'L': case 'T': case 'i': case 'I': { /* integer types */
int issigned = islower(opt);
lua_Number res = getinteger(data+pos, h.endian, issigned, (int)size);
lua_pushnumber(L, res);
break;
}
case 'e': {
Int64_unpack(L, data+pos, h.endian == LITTLE);
break;
}
case 'E': {
UInt64_unpack(L, data+pos, h.endian == LITTLE);
break;
}
case 'x': case 'X': {
break;
}
case 'f': {
gfloat f;
memcpy(&f, data+pos, size);
correctbytes((gchar *)&f, sizeof(f), h.endian);
lua_pushnumber(L, f);
break;
}
case 'd': {
gdouble d;
memcpy(&d, data+pos, size);
correctbytes((gchar *)&d, sizeof(d), h.endian);
lua_pushnumber(L, d);
break;
}
case 'c': {
if (size == 0) {
if (!lua_isnumber(L, -1))
luaL_error(L, "format `c0' needs a previous size");
size = wslua_toguint32(L, -1);
lua_pop(L, 1);
luaL_argcheck(L, pos+size <= ld, 2, "data string too short");
}
if (!h.noassign)
lua_pushlstring(L, data+pos, size);
break;
}
case 's': {
const gchar *e = (const char *)memchr(data+pos, '\0', ld - pos);
if (e == NULL)
luaL_error(L, "unfinished string in data");
size = (e - (data+pos)) + 1;
if (!h.noassign)
lua_pushlstring(L, data+pos, size - 1);
break;
}
case '=': {
lua_pushinteger(L, pos + 1);
break;
}
default: controloptions(L, opt, &fmt, &h);
}
pos += size;
}
lua_pushinteger(L, pos + 1);
WSLUA_RETURN(lua_gettop(L) - 2); /* One or more values based on format, plus the posoition it stopped unpacking. */
}
WSLUA_CONSTRUCTOR Struct_size (lua_State *L) {
/* Returns the length of the binary string struct that would be consumed/handled by the given format string. */
#define WSLUA_ARG_Struct_size_FORMAT 1 /* The format string */
Header h;
const gchar *fmt = luaL_checkstring(L, WSLUA_ARG_Struct_size_FORMAT);
size_t pos = 0;
defaultoptions(&h);
while (*fmt) {
int opt = *fmt++;
size_t size = optsize(L, opt, &fmt);
pos += gettoalign(pos, &h, opt, size);
if (opt == 's')
luaL_argerror(L, 1, "option 's' has no fixed size");
else if (opt == 'c' && size == 0)
luaL_argerror(L, 1, "option 'c0' has no fixed size");
if (!isalnum(opt))
controloptions(L, opt, &fmt, &h);
pos += size;
}
lua_pushinteger(L, pos);
WSLUA_RETURN(1); /* The size number */
}
WSLUA_CONSTRUCTOR Struct_tohex (lua_State *L) {
/* Converts the passed-in binary string to a hex-ascii string. */
#define WSLUA_ARG_Struct_tohex_BYTESTRING 1 /* A Lua string consisting of binary bytes */
#define WSLUA_OPTARG_Struct_tohex_LOWERCASE 2 /* True to use lower-case hex characters (default=false). */
#define WSLUA_OPTARG_Struct_tohex_SEPARATOR 3 /* A string separator to insert between hex bytes (default=nil). */
const gchar* s = NULL;
size_t len = 0;
gboolean lowercase = FALSE;
const gchar* sep = NULL;
s = luaL_checklstring(L,WSLUA_ARG_Struct_tohex_BYTESTRING,&len);
if (!s) {
WSLUA_ARG_ERROR(Struct_tohex,BYTESTRING,"must be a Lua string");
return 0;
}
lowercase = wslua_optbool(L,WSLUA_OPTARG_Struct_tohex_LOWERCASE,FALSE);
sep = luaL_optstring(L,WSLUA_OPTARG_Struct_tohex_SEPARATOR,NULL);
wslua_bin2hex(L, s, (guint)len, lowercase, sep);
WSLUA_RETURN(1); /* The Lua hex-ascii string */
}
WSLUA_CONSTRUCTOR Struct_fromhex (lua_State *L) {
/* Converts the passed-in hex-ascii string to a binary string. */
#define WSLUA_ARG_Struct_fromhex_HEXBYTES 1 /* A string consisting of hexadecimal bytes like "00 B1 A2" or "1a2b3c4d" */
#define WSLUA_OPTARG_Struct_fromhex_SEPARATOR 2 /* A string separator between hex bytes/words (default=" "). */
const gchar* s = NULL;
size_t len = 0;
const gchar* sep = NULL;
s = luaL_checklstring(L,WSLUA_ARG_Struct_fromhex_HEXBYTES,&len);
if (!s) {
WSLUA_ARG_ERROR(Struct_tohex,BYTESTRING,"must be a Lua string");
return 0;
}
sep = luaL_optstring(L,WSLUA_OPTARG_Struct_fromhex_SEPARATOR,NULL);
wslua_hex2bin(L, s, (guint)len, sep);
WSLUA_RETURN(1); /* The Lua binary string */
}
/* }====================================================== */
/* Gets registered as metamethod automatically by WSLUA_REGISTER_CLASS/META */
static int Struct__gc(lua_State* L _U_) {
return 0;
}
WSLUA_METHODS Struct_methods[] = {
WSLUA_CLASS_FNREG(Struct,pack),
WSLUA_CLASS_FNREG(Struct,unpack),
WSLUA_CLASS_FNREG(Struct,size),
WSLUA_CLASS_FNREG(Struct,tohex),
WSLUA_CLASS_FNREG(Struct,fromhex),
{ NULL, NULL }
};
WSLUA_META Struct_meta[] = {
{ NULL, NULL }
};
LUALIB_API int Struct_register(lua_State* L) {
WSLUA_REGISTER_CLASS(Struct);
return 0;
}
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