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Diffstat (limited to 'epan/wslua/wslua_struct.c')
| -rw-r--r-- | epan/wslua/wslua_struct.c | 671 |
1 files changed, 671 insertions, 0 deletions
diff --git a/epan/wslua/wslua_struct.c b/epan/wslua/wslua_struct.c new file mode 100644 index 0000000..7d62dc0 --- /dev/null +++ b/epan/wslua/wslua_struct.c @@ -0,0 +1,671 @@ +/****************************************************************************** +* Copyright (C) 2010-2012 Lua.org, PUC-Rio. All rights reserved. +* +* SPDX-License-Identifier: MIT +* +******************************************************************************/ +/* +** {====================================================== +** Library for packing/unpacking structures. +** 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/UInt64 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: +** i/I - signed/unsigned int +** l/L - signed/unsigned long +** f - float +** T - size_t +** +** Following are system-independent sizes: +** b/B - signed/unsigned byte +** h/H - signed/unsigned short +** 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 +** d - double +** 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 "config.h" + +#include <assert.h> +#include <limits.h> +#include <stddef.h> +#include <string.h> + +#include <stdio.h> + +#include "wslua.h" + +/* WSLUA_MODULE Struct Binary encode/decode support + + The Struct class offers basic facilities to convert Lua values to and from C-style structs + in binary Lua strings. This is based on Roberto Ierusalimschy's Lua struct library found + in http://www.inf.puc-rio.br/~roberto/struct/, with some minor modifications as follows: + * Added support for `Int64`/`UInt64` being packed/unpacked, using 'e'/'E'. + * 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 using '`(`' & '`)`'. + + All but the first of those changes are based on an email from Flemming Madsen, on the lua-users + mailing list, which can be found http://lua-users.org/lists/lua-l/2009-10/msg00572.html[here]. + + The main functions are `Struct.pack`, which packs multiple Lua values into a struct-like + Lua binary string; and `Struct.unpack`, which unpacks multiple Lua values from a given + struct-like Lua binary string. There are some additional helper functions available as well. + + All functions in the Struct library are called as static member functions, not object methods, + so they are invoked as "Struct.pack(...)" instead of "object:pack(...)". + + The fist argument to several of the `Struct` functions is a format string, which describes + the layout of the structure. The format string is a sequence of conversion elements, which + respect the current endianness and the current alignment requirements. Initially, the + current endianness is the machine's native endianness and the current alignment requirement + is 1 (meaning no alignment at all). You can change these settings with appropriate directives + in the format string. + + The supported elements in the format string are as follows: + + * `$$ $$' (empty space) ignored. + * `++!++__n__' flag to set the current alignment requirement to 'n' (necessarily a power of 2); + an absent 'n' means the machine's native alignment. + * `++>++' flag to set mode to big endian (i.e., network-order). + * `++<++' flag to set mode to little endian. + * `++x++' a padding zero byte with no corresponding Lua value. + * `++b++' a signed char. + * `++B++' an unsigned char. + * `++h++' a signed short (native size). + * `++H++' an unsigned short (native size). + * `++l++' a signed long (native size). + * `++L++' an unsigned long (native size). + * `++T++' a size_t (native size). + * `++i++__n__' a signed integer with 'n' bytes. An absent 'n' means the native size of an int. + * `++I++__n__' like `++i++__n__' but unsigned. + * `++e++' signed 8-byte Integer (64-bits, long long), to/from a +Int64+ object. + * `++E++' unsigned 8-byte Integer (64-bits, long long), to/from a +UInt64+ object. + * `++f++' a float (native size). + * `++d++' a double (native size). + * `++s++' a zero-terminated string. + * `++c++__n__' a sequence of exactly 'n' chars corresponding to a single Lua string. An absent 'n' + means 1. When packing, the given string must have at least 'n' characters (extra + characters are discarded). + * `++c0++' this is like `++c++__n__', except that the 'n' is given by other means: When packing, 'n' is + the length of the given string; when unpacking, 'n' is the value of the previous unpacked + value (which must be a number). In that case, this previous value is not returned. + * `++x++__n__' pad to 'n' number of bytes, default 1. + * `++X++__n__' pad to 'n' alignment, default MAXALIGN. + * `++(++' to stop assigning items, and `++)++' start assigning (padding when packing). + * `++=++' to return the current position / offset. + + [NOTE] + ==== + Using `i`, `I`, `h`, `H`, `l`, `L`, `f`, and `T` is strongly discouraged, as those sizes + are system-dependent. Use the explicitly sized variants instead, such as `i4` or `E`. + + Unpacking of `i`/`I` is done to a Lua number, a double-precision floating point, + so unpacking a 64-bit field (`i8`/`I8`) will lose precision. + Use `e`/`E` to unpack into a Wireshark `Int64`/`UInt64` object instead. + ==== + + @since 1.11.3 + */ + + +/* The following line is here so that make-reg.py 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, so... + WSLUA_CLASS_DEFINE_BASE(Struct,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 endianness 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 (!g_ascii_isdigit(**fmt)) /* no number? */ + return df; /* return default value */ + else { + int a = 0; + do { + a = a*10 + *((*fmt)++) - '0'; + } while (g_ascii_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 endianness 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 endianness 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 endianness - 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_VALUE 2 /* One or more Lua value(s) to encode, based on the given format. */ + luaL_Buffer b; + const char *fmt = wslua_checkstring_only(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 endianness 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 additional 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 = wslua_checkstring_only(L, WSLUA_ARG_Struct_unpack_FORMAT); + size_t ld; + const char *data = wslua_checklstring_only(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 control options, '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 = g_ascii_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 position it stopped unpacking. */ +} + + +WSLUA_CONSTRUCTOR Struct_size (lua_State *L) { + /* Returns the length of a binary string 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 = wslua_checkstring_only(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 (!g_ascii_isalnum(opt)) + controloptions(L, opt, &fmt, &h); + pos += size; + } + lua_pushinteger(L, pos); + WSLUA_RETURN(1); /* The size number */ +} + +WSLUA_CONSTRUCTOR Struct_values (lua_State *L) { + /* Returns the number of Lua values contained in the given format string. + This will be the number of returned values from a call to Struct.unpack() + not including the extra return value of offset position. (i.e., Struct.values() + does not count that extra return value) This will also be the number of + arguments Struct.pack() expects, not including the format string argument. */ +#define WSLUA_ARG_Struct_values_FORMAT 1 /* The format string */ + Header h; + const gchar *fmt = wslua_checkstring_only(L, WSLUA_ARG_Struct_values_FORMAT); + size_t vals = 0; + defaultoptions(&h); + while (*fmt) { + int opt = *fmt++; + /* we use a size != 0 to mean it is a value */ + size_t size = optsize(L, opt, &fmt); + /* but some will be zero and not be a value, or vice-versa */ + switch (opt) { + case 's': case 'c': + /* these are values */ + size = 1; + break; + case 'x': case 'X': + /* these are not */ + size = 0; + break; + default: + break; + } + if (!g_ascii_isalnum(opt)) + controloptions(L, opt, &fmt, &h); + else if (size && !h.noassign) + vals++; + } + lua_pushinteger(L, vals); + WSLUA_RETURN(1); /* The number of values */ +} + +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; + + /* luaL_checklstring coerces the argument to a string, and that's ok for tohex, + just not fromhex. In fact, we should accept/coerce a Int64/UInt64 here too someday. */ + s = luaL_checklstring(L, WSLUA_ARG_Struct_tohex_BYTESTRING, &len); + + 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 none). */ + const gchar* s = NULL; + size_t len = 0; + const gchar* sep = NULL; + + /* luaL_checklstring coerces the argument to a string, and we don't want to do that */ + s = wslua_checklstring_only(L, WSLUA_ARG_Struct_fromhex_HEXBYTES, &len); + + 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,values), + 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; +} + +/* + * Editor modelines - https://www.wireshark.org/tools/modelines.html + * + * Local Variables: + * c-basic-offset: 2 + * tab-width: 8 + * indent-tabs-mode: nil + * End: + * + * vi: set shiftwidth=2 tabstop=8 expandtab: + * :indentSize=2:tabSize=8:noTabs=true: + */ |