src/tcpedit/plugins/dlt_linuxsll/linuxsll.c
/* $Id$ */
/*
* Copyright (c) 2001-2010 Aaron Turner <aturner at synfin dot net>
* Copyright (c) 2013-2024 Fred Klassen <tcpreplay at appneta dot com> - AppNeta
*
* The Tcpreplay Suite of tools 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 3 of the
* License, or with the authors permission any later version.
*
* The Tcpreplay Suite 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 the Tcpreplay Suite. If not, see <http://www.gnu.org/licenses/>.
*/
#include "linuxsll.h"
#include "../ethernet.h"
#include "dlt_utils.h"
#include "tcpedit.h"
#include "tcpedit_stub.h"
#include <stdlib.h>
#include <string.h>
static char dlt_name[] = "linuxsll";
static char _U_ dlt_prefix[] = "linuxsll";
static uint16_t dlt_value = DLT_LINUX_SLL;
/*
* Function to register ourselves. This function is always called, regardless
* of what DLT types are being used, so it shouldn't be allocating extra buffers
* or anything like that (use the dlt_linuxsll_init() function below for that).
* Tasks:
* - Create a new plugin struct
* - Fill out the provides/requires bit masks. Note: Only specify which fields are
* actually in the header.
* - Add the plugin to the context's plugin chain
* Returns: TCPEDIT_ERROR | TCPEDIT_OK | TCPEDIT_WARN
*/
int
dlt_linuxsll_register(tcpeditdlt_t *ctx)
{
tcpeditdlt_plugin_t *plugin;
assert(ctx);
/* create a new plugin structure */
plugin = tcpedit_dlt_newplugin();
/* FIXME: set what we provide & require */
plugin->provides += PLUGIN_MASK_PROTO + PLUGIN_MASK_SRCADDR;
plugin->
requires
+= 0;
/* what is our DLT value? */
plugin->dlt = dlt_value;
/* set the prefix name of our plugin. This is also used as the prefix for our options */
plugin->name = safe_strdup(dlt_prefix);
/*
* Point to our functions, note, you need a function for EVERY method.
* Even if it is only an empty stub returning success.
*/
plugin->plugin_init = dlt_linuxsll_init;
plugin->plugin_cleanup = dlt_linuxsll_cleanup;
plugin->plugin_parse_opts = dlt_linuxsll_parse_opts;
plugin->plugin_decode = dlt_linuxsll_decode;
plugin->plugin_encode = dlt_linuxsll_encode;
plugin->plugin_proto = dlt_linuxsll_proto;
plugin->plugin_l2addr_type = dlt_linuxsll_l2addr_type;
plugin->plugin_l2len = dlt_linuxsll_l2len;
plugin->plugin_get_layer3 = dlt_linuxsll_get_layer3;
plugin->plugin_merge_layer3 = dlt_linuxsll_merge_layer3;
plugin->plugin_get_mac = dlt_linuxsll_get_mac;
/* add it to the available plugin list */
return tcpedit_dlt_addplugin(ctx, plugin);
}
/*
* Initializer function. This function is called only once, if and only if
* this plugin will be utilized. Remember, if you need to keep track of any state,
* store it in your plugin->config, not a global!
* Returns: TCPEDIT_ERROR | TCPEDIT_OK | TCPEDIT_WARN
*/
int
dlt_linuxsll_init(tcpeditdlt_t *ctx)
{
tcpeditdlt_plugin_t *plugin;
assert(ctx);
if ((plugin = tcpedit_dlt_getplugin(ctx, dlt_value)) == NULL) {
tcpedit_seterr(ctx->tcpedit, "Unable to initialize unregistered plugin %s", dlt_name);
return TCPEDIT_ERROR;
}
/* allocate memory for our decode extra data */
if (ctx->decoded_extra_size > 0) {
if (ctx->decoded_extra_size < sizeof(linuxsll_extra_t)) {
ctx->decoded_extra_size = sizeof(linuxsll_extra_t);
ctx->decoded_extra = safe_realloc(ctx->decoded_extra, ctx->decoded_extra_size);
}
} else {
ctx->decoded_extra_size = sizeof(linuxsll_extra_t);
ctx->decoded_extra = safe_malloc(ctx->decoded_extra_size);
}
/* allocate memory for our config data */
plugin->config_size = sizeof(linuxsll_config_t);
plugin->config = safe_malloc(plugin->config_size);
return TCPEDIT_OK; /* success */
}
/*
* Since this is used in a library, we should manually clean up after ourselves
* Unless you allocated some memory in dlt_linuxsll_init(), this is just an stub.
* Returns: TCPEDIT_ERROR | TCPEDIT_OK | TCPEDIT_WARN
*/
int
dlt_linuxsll_cleanup(tcpeditdlt_t *ctx)
{
tcpeditdlt_plugin_t *plugin;
assert(ctx);
if ((plugin = tcpedit_dlt_getplugin(ctx, dlt_value)) == NULL) {
tcpedit_seterr(ctx->tcpedit, "Unable to cleanup unregistered plugin %s", dlt_name);
return TCPEDIT_ERROR;
}
safe_free(plugin->name);
plugin->name = NULL;
safe_free(plugin->config);
plugin->config = NULL;
plugin->config_size = 0;
return TCPEDIT_OK; /* success */
}
/*
* This is where you should define all your AutoGen AutoOpts option parsing.
* Any user specified option should have it's bit turned on in the 'provides'
* bit mask.
* Returns: TCPEDIT_ERROR | TCPEDIT_OK | TCPEDIT_WARN
*/
int
dlt_linuxsll_parse_opts(tcpeditdlt_t *ctx)
{
assert(ctx);
/* nothing to parse */
return TCPEDIT_OK; /* success */
}
/*
* Function to decode the layer 2 header in the packet.
* You need to fill out:
* - ctx->l2len
* - ctx->srcaddr
* - ctx->dstaddr
* - ctx->proto
* - ctx->decoded_extra
* Returns: TCPEDIT_ERROR | TCPEDIT_OK | TCPEDIT_WARN
*/
int
dlt_linuxsll_decode(tcpeditdlt_t *ctx, const u_char *packet, int pktlen)
{
int type;
linux_sll_header_t *linux_sll;
assert(ctx);
assert(packet);
if (pktlen < (int)sizeof(linux_sll_header_t))
return TCPEDIT_ERROR;
linux_sll = (linux_sll_header_t *)packet;
ctx->proto = linux_sll->proto;
ctx->l2len = sizeof(linux_sll_header_t);
type = ntohs(linux_sll->type);
if (type == ARPHRD_ETHER || type == ARPHRD_LOOPBACK) { /* ethernet or loopback */
memcpy(&(ctx->srcaddr), linux_sll->address, ETHER_ADDR_LEN);
} else {
tcpedit_seterr(ctx->tcpedit, "%s", "DLT_LINUX_SLL pcap's must contain only ethernet or loopback packets");
return TCPEDIT_ERROR;
}
return TCPEDIT_OK; /* success */
}
/*
* Function to encode the layer 2 header back into the packet.
* Returns: total packet len or TCPEDIT_ERROR
*/
int
dlt_linuxsll_encode(tcpeditdlt_t *ctx, u_char *packet, _U_ int pktlen, _U_ tcpr_dir_t dir)
{
assert(ctx);
assert(packet);
tcpedit_seterr(ctx->tcpedit, "%s", "DLT_LINUX_SLL plugin does not support packet encoding");
return TCPEDIT_ERROR;
}
/*
* Function returns the Layer 3 protocol type of the given packet, or TCPEDIT_ERROR on error
*/
int
dlt_linuxsll_proto(tcpeditdlt_t *ctx, const u_char *packet, int pktlen)
{
linux_sll_header_t *linux_sll;
assert(ctx);
assert(packet);
if (pktlen < (int)sizeof(linux_sll_header_t))
return TCPEDIT_ERROR;
linux_sll = (linux_sll_header_t *)packet;
return linux_sll->proto;
}
/*
* Function returns a pointer to the layer 3 protocol header or NULL on error
*/
u_char *
dlt_linuxsll_get_layer3(tcpeditdlt_t *ctx, u_char *packet, int pktlen)
{
int l2len;
assert(ctx);
assert(packet);
l2len = dlt_linuxsll_l2len(ctx, packet, pktlen);
if (l2len == -1 || pktlen < l2len)
return NULL;
return tcpedit_dlt_l3data_copy(ctx, packet, pktlen, l2len);
}
/*
* function merges the packet (containing L2 and old L3) with the l3data buffer
* containing the new l3 data. Note, if L2 % 4 == 0, then they're pointing to the
* same buffer, otherwise there was a memcpy involved on strictly aligned architectures
* like SPARC
*/
u_char *
dlt_linuxsll_merge_layer3(tcpeditdlt_t *ctx, u_char *packet, int pktlen, u_char *ipv4_data, u_char *ipv6_data)
{
int l2len;
assert(ctx);
assert(packet);
assert(ipv4_data || ipv6_data);
l2len = dlt_linuxsll_l2len(ctx, packet, pktlen);
if (l2len == -1 || pktlen < l2len)
return NULL;
return tcpedit_dlt_l3data_merge(ctx, packet, pktlen, ipv4_data ?: ipv6_data, l2len);
}
/*
* return the length of the L2 header of the current packet
*/
int
dlt_linuxsll_l2len(tcpeditdlt_t *ctx, const u_char *packet, int pktlen)
{
assert(ctx);
assert(packet);
if (pktlen < (int)sizeof(linux_sll_header_t))
return -1;
return sizeof(linux_sll_header_t);
}
/*
* return a static pointer to the source/destination MAC address
* return NULL on error/address doesn't exist
*/
u_char *
dlt_linuxsll_get_mac(tcpeditdlt_t *ctx, tcpeditdlt_mac_type_t mac, const u_char *packet, int pktlen)
{
assert(ctx);
assert(packet);
if (pktlen < 14)
return NULL;
/* FIXME: return a ptr to the source or dest mac address. */
switch (mac) {
case SRC_MAC:
memcpy(ctx->srcmac, &packet[6], 8); /* linuxssl defines the src mac field to be 8 bytes, not 6 */
return (ctx->srcmac);
case DST_MAC:
return (NULL);
default:
errx(-1, "Invalid tcpeditdlt_mac_type_t: %d", mac);
}
}
tcpeditdlt_l2addr_type_t
dlt_linuxsll_l2addr_type(void)
{
/* we only support ethernet packets */
return ETHERNET;
}