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/*
* Copyright (C) 2010 University of Basel <http://cn.cs.unibas.ch/>
* by Andre Graf <andre@dergraf.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <http://www.gnu.org/licenses/>.
*/

#include "controller.h"



struct protocol_buf * dyn_prot_buf_array[MAX_NR_OF_DYN_PROT_BUFS] = { NULL };


/* LUA_API: the function 'field_dynamic_setter' acts as a wrapper around
* a given Lua field setter function of a dynamic protocol buffer. The
* string containing the lua function name was piggybacked in the 'set'
* member of the protocol_field. We call this function passing the actual
* segment as byte array and the set value.
*
* Paramters:
* 1. lua_packet_segment (implicit)
* 2. some lua value
*
* Upvalues:
* 1. pointer to the protocol buffer
* 2. field index
*
* Returns:
* 1. true or false if the 'set' was successful
*/
int32_t field_dynamic_setter(lua_State *L)
{
size_t nbytes;
lua_packet_segment * array;
struct protocol_buf * prot_buf = (struct protocol_buf *)lua_topointer(L, lua_upvalueindex(1));
lua_packet_segment * seg = checkpacketseg(L, 1, prot_buf->name);

int32_t field_index = lua_tointeger(L, lua_upvalueindex(2));
    
/* the function name is piggybacked as a string */
lua_getglobal(L, (char *)prot_buf->protocol_fields[field_index].set);
if (!lua_isfunction(L, -1)) {
lua_pushboolean(L, 0);
return 1;
}

nbytes = sizeof(lua_packet_segment) + seg->length * sizeof(uint8_t);
array = (lua_packet_segment *)lua_newuserdata(L, nbytes);
array->length = seg->length;
array->start = seg->start + seg->offset;
array->changes = NULL;

luaL_getmetatable(L, LUA_BYTE_ARRAY);
lua_setmetatable(L, -2);
lua_pushvalue(L, 2); /* push value to set */
if (lua_pcall(L, 2, 1, 0) != 0) {
pr_debug("Error: %s \n", lua_tostring(L, -1));
lua_pop(L, 1);
lua_pushboolean(L, 0);
}
return 1;
}

/* LUA_API: the function 'field_dynamic_getter' acts as a wrapper around
* a given Lua field getter function of a dynamic protocol buffer. The
* string containing the lua function name was piggybacked in the 'get'
* member of the protocol_field. We call this function passing the actual
* segment as byte array.
*
* Paramters:
* 1. lua_packet_segment (implicit)
*
* Upvalues:
* 1. pointer to the protocol buffer
* 2. field index
*
* Returns:
* 1. true or false if the 'get' was successful
*/
int32_t field_dynamic_getter(lua_State *L)
{
size_t nbytes;
lua_packet_segment * array;
struct protocol_buf * prot_buf = (struct protocol_buf *)lua_topointer(L, lua_upvalueindex(1));
lua_packet_segment * seg = checkpacketseg(L, 1, prot_buf->name);

int32_t field_index = lua_tointeger(L, lua_upvalueindex(2));
    
/* the function name is piggybacked as a string */
lua_getglobal(L, (char *)prot_buf->protocol_fields[field_index].get);
if (!lua_isfunction(L, -1)) {
lua_pushboolean(L, 0);
return 1;
}

nbytes = sizeof(lua_packet_segment) + seg->length * sizeof(uint8_t);
array = (lua_packet_segment *)lua_newuserdata(L, nbytes);
array->length = seg->length;
array->start = seg->start + seg->offset;
array->changes = NULL;

luaL_getmetatable(L, LUA_BYTE_ARRAY);
lua_setmetatable(L, -2);
if (lua_pcall(L, 1, 1, 0) != 0) {
pr_debug("Error: %s \n", luaL_checkstring(L, -1));
lua_pop(L, 1);
lua_pushboolean(L, 0);
}
return 1;
}

/* LUA_API: the function 'has_protocol_dynamic' acts as a wrapper around
* a given lua has_protocol function of a dynamic protocol buffer. The
* string containing the lua function name was piggybacked in the 'has_protocol'
* member of the protocol_buffer. We call this function passing the actual
* segment.
*
* Paramters:
* 1. lua_packet_segment
* 2. protocol type
*
* Returns:
* 1. true or false if the payload field contains the given protocol
*/
int32_t has_protocol_dynamic(lua_State *L, struct protocol_buf * prot_buf, lua_packet_segment * seg, int32_t type)
{
lua_packet_segment *seg_new;
int32_t res = 0;

    /* the function name is piggybacked as a string */
lua_getglobal(L, (char *)prot_buf->has_protocol);
seg_new = (lua_packet_segment *)lua_newuserdata(L, sizeof(lua_packet_segment));
seg_new->start = seg->start;
seg_new->offset = seg->offset;
seg_new->length = seg->length;
seg_new->changes = NULL;
luaL_getmetatable(L, prot_buf->name);
lua_setmetatable(L, -2);
lua_pushinteger(L, type); /* push the protocol type */
if (lua_pcall(L, 2, 1, 0) != 0) {
pr_debug("Error: %s \n", luaL_checkstring(L, -1));
lua_pop(L, 1);
return 0;
}
res = lua_toboolean(L, -1);
lua_pop(L, 1);

return res;
}

/* LUA_API: the function 'get_field_changes_dynamic' acts as a wrapper around
* a given lua get_field_changes function of a dynamic protocol buffer. The
* string containing the lua function name was piggybacked in the 'get_field_changes'
* member of the protocol_buffer. We call this function passing the actual
* segment. The lua function must return two lua table containing the offset
* and length changes (in bits).
*
* Paramters:
* 1. lua_packet_segment
*
* Returns:
* 1. new allocated field_changes struct
*/
struct field_changes * get_field_changes_dynamic(lua_State *L, struct protocol_buf *prot_buf, lua_packet_segment * seg)
{
lua_packet_segment *seg_new;
struct field_changes * changes;
int32_t nr_of_changes, i;

lua_getglobal(L, (char *)prot_buf->get_field_changes);

seg_new = (lua_packet_segment *)lua_newuserdata(L, sizeof(lua_packet_segment));
seg_new->start = seg->start;
seg_new->offset = seg->offset;
seg_new->length = seg->length;
seg_new->changes = NULL;
luaL_getmetatable(L, prot_buf->name);
lua_setmetatable(L, -2);

if (lua_pcall(L, 1, 2, 0) != 0)
luaL_error(L, "inside get_field_changes_dynamic. %s\n", lua_tostring(L, -1));

/* the function call must return a table containing length changes */
luaL_checktype(L, -1, LUA_TTABLE);
/* the function call must return a table containing offset changes */
luaL_checktype(L, -2, LUA_TTABLE);
/* both tables have to be of same size */
if (lua_objlen(L, -1) != lua_objlen(L, -2))
luaL_error(L, "the provided tables are not of equal size");

nr_of_changes = lua_objlen(L, -1);
changes = get_allocated_field_changes(L, nr_of_changes);

/* loop over the tables */
for (i = 1; i < nr_of_changes; i++) {
lua_rawgeti(L, -1, i); /* push length value of field at index i */
changes->field_length_changes[i - 1] = luaL_checkinteger(L, -1);
lua_pop(L, 1); /* pop offset value */

lua_rawgeti(L, -2, i); /* push offset value of field at index i */
changes->field_offset_changes[i - 1] = luaL_checkinteger(L, -1);
lua_pop(L, 1); /* pop length value */
}

/* pop both tables */
lua_pop(L, 2);

return changes;
}

/* C_INT: 'get_free_protocol_index' is only used internally. This function
* gets a free slot inside the array holding all the protocol buffers.
* There are several ways to get to this information. In this case I take
* the way over the reflected array SUPPORTED_PROTOCOL_TABLE inside the
* Lua state. Since this function is called at laodtime, we do not have
* to care about performance.
*/
static int32_t get_free_protocol_index(lua_State *L)
{
int32_t protocol_index;

lua_getglobal(L, SUPPORTED_PROTOCOL_TABLE);
protocol_index = lua_objlen(L, -1) + 1;
lua_pop(L, 1);
return protocol_index;
}

/* C_API: 'free_dynamic_prot_buf' frees the allocated memory of a given
* dynamic protocol buffer. this function is normally called inside a
* cleanup routine. Be aware, before running this function you must be
* sure that no references to the dynamic protocol buffers were available.
* It's recomended to close the Lua state before calling the function. */
void free_dynamic_prot_buf(struct protocol_buf * prot_buf)
{
struct protocol_field * field = prot_buf->protocol_fields;

for (; field->name != NULL; field++) {
if (field->get) kfree(field->get);
if (field->set) kfree(field->set);
if (field->name) kfree((char *)field->name);
}

if (prot_buf->payload_field) kfree(prot_buf->payload_field);
if (prot_buf->has_protocol) kfree(prot_buf->has_protocol);

if (prot_buf->get_field_changes) kfree(prot_buf->get_field_changes);
kfree((char *)prot_buf->name);
kfree(prot_buf);
return;
}

void cleanup_dynamic_prot_bufs(void)
{
int32_t i;

for (i = 0; i < MAX_NR_OF_DYN_PROT_BUFS; i++) {
if (dyn_prot_buf_array[i]) {
free_dynamic_prot_buf(dyn_prot_buf_array[i]);
dyn_prot_buf_array[i] = NULL;
}
}
return;
}


/* C_INT: 'free_protocol_fields' is used internally as a helper function for
* 'register_dynamic_protbuf'. It is used when durin registration an error
* occurs and the afore allocated fields needed to be freed. */
static inline void free_protocol_fields(struct protocol_field * prot_fields, int32_t i)
{
struct protocol_field * f;

while (i >= 0) {
f = &prot_fields[i];
if (f->name) kfree((void *)f->name);
if (f->get) kfree((void *)f->get);
if (f->set) kfree((void *)f->set);
kfree((void *)f);
i--;
}
}

/* LUA_API: 'register_dynamic_protbuf' is called from within the Lua script.
* it takes a Lua table representing the dynamic protocol buffer as parameter.
* e.g.:
* eth_prot_buf = {
* name = "packet_eth_dyn",
* payload_field = "data",
* protocol_fields = {
* {"dmac", 0, 48, nil, nil },
* {"smac", 48, 48, nil, nil },
* {"type", 96, 16, nil, nil },
* {"data", 112, 0, nil, nil },
* },
* has_protocol = "eth_dyn_has_protocol",
* get_field_changes = "eth_dyn_get_field_changes"
* }
* register_dynamic_protbuf(eth_prot_buf)
*
* the table gets parsed and a new protocol_buf struct is allocated and
* initialized using 'register_protbuf', which is also used for the static
* protocol buffers. This enables an identical behavior like the static
* protocol buffers. The dynamic protocol buffers are not garbage collected,
* use 'free_dynamic_protbuf' to free them after closing the Lua state.
*/
static int32_t register_dynamic_protbuf(lua_State *L)
{
struct protocol_buf *prot_buf;
struct protocol_field *field, sentinel = PROT_FIELD_SENTINEL;
int32_t nr_of_fields, i;

prot_buf = (struct protocol_buf *)kmalloc(sizeof(struct protocol_buf), GFP_KERNEL);
prot_buf->is_dynamic = 1;

/* check if parameter is a table */
luaL_checktype(L, 1, LUA_TTABLE);

/* initialize prot_buf.name */
lua_getfield(L, 1, "name");
prot_buf->name = kmalloc(lua_objlen(L, -1), GFP_KERNEL);
strcpy((char *)prot_buf->name, luaL_checkstring(L, -1));
lua_pop(L, 1); /* pop res from lua_getfield */

/* check if protocol buffer is already registered */
lua_getglobal(L, prot_buf->name);
if (!lua_isnil(L, -1)) {
lua_pop(L, 1); /* pop res from lua_getglobal */
pr_debug("protocol_buf '%s' already registered.\n", prot_buf->name);
goto free_prot_buf;
}
lua_pop(L, 1); /* pop res from lua_getglobal */

/* initialize payload field */
lua_getfield(L, 1, "payload_field");
if (lua_isstring(L, -1)) {
prot_buf->payload_field = kmalloc(lua_objlen(L, -1), GFP_KERNEL);
strcpy(prot_buf->payload_field, lua_tostring(L, -1));
}else
prot_buf->payload_field = NULL;
lua_pop(L, 1); /* pop res from lua_getfield */

/* initialize protocol_fields field*/
lua_getfield(L, 1, "protocol_fields");
if (!lua_istable(L, -1)) {
pr_debug("invalid protocol_fields table.\n");
goto err2;

}

nr_of_fields = lua_objlen(L, -1);
prot_buf->protocol_fields = (struct protocol_field *)kmalloc((nr_of_fields + 1) * sizeof(struct protocol_field), GFP_KERNEL);

for (i = 1; i <= nr_of_fields; i++) {
field = &prot_buf->protocol_fields[i - 1];
/* initialize protocol field */
lua_rawgeti(L, -1, i); /* push field-table */
if (!lua_istable(L, -1)) {
free_protocol_fields(prot_buf->protocol_fields, i);
pr_debug("invalid protocol_field at %i.\n", i);
goto err;
}

/* initialize protocol field name */
lua_rawgeti(L, -1, 1);
if (!lua_isstring(L, -1)) {
free_protocol_fields(prot_buf->protocol_fields, i);
pr_debug("invalid protocol_field name at %i.\n", i);
goto err;
}

field->name = kmalloc(lua_objlen(L, -1), GFP_KERNEL);
strcpy((char*)field->name, lua_tostring(L, -1));
lua_pop(L, 1); /* pop field name */

/* initialize protocol field offset */
lua_rawgeti(L, -1, 2);
if (!lua_isnumber(L, -1)) {
free_protocol_fields(prot_buf->protocol_fields, i);
pr_debug("invalid protocol_field offset at %i.\n", i);
goto err;
}
field->offset = lua_tointeger(L, -1);
lua_pop(L, 1); /* pop field offset */

/* initialize protocol field length */
lua_rawgeti(L, -1, 3);
if (!lua_isnumber(L, -1)) {
free_protocol_fields(prot_buf->protocol_fields, i);
pr_debug("invalid protocol_field length at %i.\n", i);
goto err;
}
field->length = lua_tointeger(L, -1);
lua_pop(L, 1); /* pop field length */

/* initialize protocol field getter */
lua_rawgeti(L, -1, 4);
if (lua_isstring(L, -1)) {
field->get = kmalloc(lua_objlen(L, -1), GFP_KERNEL);
strcpy((char *)field->get, lua_tostring(L, -1)); /* the get-wrapper knows about the piggybacked string */
}else
field->get = NULL;
lua_pop(L, 1); /* pop field getter */

/* initialize protocol field setter */
lua_rawgeti(L, -1, 5);
if (lua_isstring(L, -1)) {
field->set = kmalloc(lua_objlen(L, -1), GFP_KERNEL);
strcpy((char *)field->set, lua_tostring(L, -1)); /* the set-wrapper knows about the piggybacked string */
}else
field->set = NULL;
lua_pop(L, 1); /* pop field setter */

/* field initialization completed */
lua_pop(L, 1); /* pop field-table */
}

/* put sentinel at the end of protocol_fields */
memcpy(&prot_buf->protocol_fields[nr_of_fields], &sentinel, sizeof(sentinel));
lua_pop(L, 1); /* pop protocol-fields-table */

/* initialize has_protocol field */
lua_getfield(L, 1, "has_protocol");
if (lua_isstring(L, -1)) {
prot_buf->has_protocol = kmalloc(lua_objlen(L, -1), GFP_KERNEL);
strcpy((char *)prot_buf->has_protocol, lua_tostring(L, -1)); /* the has_protocol-wrapper knows about the piggybacked string */
}else
prot_buf->has_protocol = NULL;
lua_pop(L, 1); /* pop has_protocol */

/* initialize get_field_changes field */
lua_getfield(L, 1, "get_field_changes");
if (lua_isstring(L, -1)) {
prot_buf->get_field_changes = kmalloc(lua_objlen(L, -1), GFP_KERNEL);
strcpy((char *)prot_buf->get_field_changes, lua_tostring(L, -1)); /* the get_field_changes-wrapper knows about the piggybacked string */
}else
prot_buf->get_field_changes = NULL;
lua_pop(L, 1); /* pop get_field_changes */

/* Storing the pointer to the DYNAMIC protbuf within dyn_prot_buf_array, in order to free it at cleanup */
for (i = 0; i < MAX_NR_OF_DYN_PROT_BUFS; i++) {
if (!dyn_prot_buf_array[i]) {
dyn_prot_buf_array[i] = prot_buf;
break;
}else
goto err;
}

/* call the "common" register_protbuf */
register_protbuf(L, prot_buf, get_free_protocol_index(L)); /* register prot_buf as it is done with the static ones */

return 0;

err:
kfree(prot_buf->protocol_fields);
err2:
if (prot_buf->payload_field) kfree(prot_buf->payload_field);
free_prot_buf:
kfree((void *)prot_buf->name);
kfree(prot_buf);

luaL_error(L, "one or more error happend while registering a dynamic protocol buffer, please consult the debug log");

return 0;

}

void luaopen_protbuf_dynamic(lua_State *L)
{
lua_getglobal(L, "_G");
lua_pushcclosure(L, register_dynamic_protbuf, 0);
lua_setfield(L, -2, "register_dynamic_protbuf");
lua_pop(L, 1); /* pop _G */
return;
}
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