jnpr_ether.c

/* $Id$ */

/*
 * Copyright (c) 2006-2007 Aaron Turner.
 * Copyright (c) 2013-2022 Fred Klassen <tcpreplay at appneta dot com> - AppNeta
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the names of the copyright owners nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
 * IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "jnpr_ether.h"
#include "dlt_utils.h"
#include "jnpr_ether_types.h"
#include "tcpedit.h"
#include "tcpedit_stub.h"
#include <dlt_en10mb/en10mb.h>
#include <stdlib.h>
#include <string.h>

static char dlt_name[] = "jnpr_eth";
static uint16_t dlt_value = DLT_JUNIPER_ETHER;

/*
 * 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_jnpr_ether_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_jnpr_ether_register(tcpeditdlt_t *ctx)
{
    tcpeditdlt_plugin_t *plugin;
    assert(ctx);

    /* create  a new plugin structure */
    plugin = tcpedit_dlt_newplugin();

    plugin->provides += PLUGIN_MASK_PROTO + PLUGIN_MASK_SRCADDR + PLUGIN_MASK_DSTADDR;
    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_name);

    /*
     * 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_jnpr_ether_init;
    plugin->plugin_post_init = dlt_jnpr_ether_post_init;
    plugin->plugin_cleanup = dlt_jnpr_ether_cleanup;
    plugin->plugin_parse_opts = dlt_jnpr_ether_parse_opts;
    plugin->plugin_decode = dlt_jnpr_ether_decode;
    plugin->plugin_encode = dlt_jnpr_ether_encode;
    plugin->plugin_proto = dlt_jnpr_ether_proto;
    plugin->plugin_l2addr_type = dlt_jnpr_ether_l2addr_type;
    plugin->plugin_l2len = dlt_jnpr_ether_l2len;
    plugin->plugin_get_layer3 = dlt_jnpr_ether_get_layer3;
    plugin->plugin_merge_layer3 = dlt_jnpr_ether_merge_layer3;
    plugin->plugin_get_mac = dlt_jnpr_ether_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_jnpr_ether_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 config data */
    plugin->config_size = sizeof(jnpr_ether_config_t);
    plugin->config = safe_malloc(plugin->config_size);

    return TCPEDIT_OK; /* success */
}

/**
 * Post init function.  This function is called only once after init() and parse_opts()
 * It basically allows decoders to properly initialize sub-plugins.
 */
int
dlt_jnpr_ether_post_init(tcpeditdlt_t *ctx)
{
    jnpr_ether_config_t *config;

    /* do nothing if we're not the decoder */
    if (ctx->decoder->dlt != dlt_value)
        return TCPEDIT_OK;

    /* init our subcontext & decoder of en10mb */
    config = (jnpr_ether_config_t *)ctx->encoder->config;
    if (config->subctx == NULL)
        config->subctx = tcpedit_dlt_init(ctx->tcpedit, DLT_EN10MB);

    return TCPEDIT_OK;
}

/*
 * Since this is used in a library, we should manually clean up after ourselves
 * Unless you allocated some memory in dlt_jnpr_ether_init(), this is just an stub.
 * Returns: TCPEDIT_ERROR | TCPEDIT_OK | TCPEDIT_WARN
 */
int
dlt_jnpr_ether_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;
    if (plugin->config != NULL) {
        /* clean up the en10mb plugin */
        jnpr_ether_config_t *config;

        config = (jnpr_ether_config_t *)ctx->encoder->config;
        if (config->subctx != NULL) {
            ctx->decoded_extra = NULL;
            tcpedit_dlt_cleanup(config->subctx);
        }
        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_jnpr_ether_parse_opts(tcpeditdlt_t *ctx)
{
    assert(ctx);

    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_jnpr_ether_decode(tcpeditdlt_t *ctx, const u_char *packet, int pktlen)
{
    int jnpr_header_len = 0;
    const u_char *ethernet = NULL;
    jnpr_ether_config_t *config;

    assert(ctx);
    assert(packet);

    /* MAGIC + Static fields + Extension Length */
    if (pktlen < JUNIPER_ETHER_HEADER_LEN)
        return TCPEDIT_ERROR;

    config = (jnpr_ether_config_t *)ctx->encoder->config;

    /* first, verify magic */
    if (memcmp(packet, JUNIPER_ETHER_MAGIC, JUNIPER_ETHER_MAGIC_LEN) != 0) {
        tcpedit_seterr(ctx->tcpedit, "Invalid magic 0x%02X%02X%02X", packet[0], packet[1], packet[2]);
        return TCPEDIT_ERROR;
    }

    /* next make sure the L2 header is present */
    if ((packet[JUNIPER_ETHER_OPTIONS_OFFSET] & JUNIPER_ETHER_L2PRESENT) != JUNIPER_ETHER_L2PRESENT) {
        tcpedit_seterr(ctx->tcpedit, "Frame is missing L2 Header: %x", packet[JUNIPER_ETHER_OPTIONS_OFFSET]);
        return TCPEDIT_ERROR;
    }

    /* then get the Juniper header length */
    memcpy(&jnpr_header_len, &packet[JUNIPER_ETHER_EXTLEN_OFFSET], 2);

    jnpr_header_len = ntohs(jnpr_header_len) + JUNIPER_ETHER_HEADER_LEN;

    dbgx(1, "jnpr header len: %d", jnpr_header_len);
    /* make sure the packet is big enough to find the Ethernet Header */

    if (pktlen < jnpr_header_len + TCPR_ETH_H) {
        tcpedit_seterr(ctx->tcpedit, "Frame is too short! %d < %d", pktlen, (jnpr_header_len + TCPR_ETH_H));
        return TCPEDIT_ERROR;
    }

    ctx->l2len = jnpr_header_len;

    /* jump to the appropriate offset */
    ethernet = packet + jnpr_header_len;

    /* let the en10mb plugin decode the rest */
    if (tcpedit_dlt_decode(config->subctx, ethernet, (pktlen - jnpr_header_len)) == TCPEDIT_ERROR)
        return TCPEDIT_ERROR;

    /* copy the subdecoder state to our encoder state */
    if (tcpedit_dlt_copy_decoder_state(ctx, config->subctx) == TCPEDIT_ERROR)
        return TCPEDIT_ERROR;

    return TCPEDIT_OK;
}

/*
 * Function to encode the layer 2 header back into the packet.
 * Returns: total packet len or TCPEDIT_ERROR
 */
int
dlt_jnpr_ether_encode(tcpeditdlt_t *ctx, u_char *packet, int pktlen, _U_ tcpr_dir_t dir)
{
    assert(ctx);
    assert(packet);

    /* MAGIC + Static fields + Extension Length */
    if (pktlen < JUNIPER_ETHER_HEADER_LEN)
        return TCPEDIT_ERROR;

    tcpedit_seterr(ctx->tcpedit, "%s", "DLT_JUNIPER_ETHER 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
 * Make sure you return this value in NETWORK byte order!
 */
int
dlt_jnpr_ether_proto(tcpeditdlt_t *ctx, const u_char *packet, int pktlen)
{
    int jnpr_hdr_len;
    const u_char *ethernet;
    jnpr_ether_config_t *config;

    assert(ctx);
    assert(packet);

    /* MAGIC + Static fields + Extension Length */
    if (pktlen < JUNIPER_ETHER_HEADER_LEN)
        return TCPEDIT_ERROR;

    config = (jnpr_ether_config_t *)ctx->encoder->config;

    /* next make sure the L2 header is present */
    if ((packet[JUNIPER_ETHER_OPTIONS_OFFSET] & JUNIPER_ETHER_L2PRESENT) != JUNIPER_ETHER_L2PRESENT) {
        tcpedit_seterr(ctx->tcpedit, "Frame is missing L2 Header: %x", packet[JUNIPER_ETHER_OPTIONS_OFFSET]);
        return TCPEDIT_ERROR;
    }

    /* then get the Juniper header length */
    memcpy(&jnpr_hdr_len, &packet[JUNIPER_ETHER_EXTLEN_OFFSET], 2);

    jnpr_hdr_len = ntohs(jnpr_hdr_len) + JUNIPER_ETHER_HEADER_LEN;
    ethernet = packet + jnpr_hdr_len;

    /* let the en10mb plugin do the rest of the work */
    return tcpedit_dlt_proto(config->subctx, DLT_EN10MB, ethernet, (pktlen - jnpr_hdr_len));
}

/*
 * Function returns a pointer to the layer 3 protocol header or NULL on error
 */
u_char *
dlt_jnpr_ether_get_layer3(tcpeditdlt_t *ctx, u_char *packet, int pktlen)
{
    int l2len;
    assert(ctx);
    assert(packet);

    /* next make sure the L2 header is present */
    if ((packet[JUNIPER_ETHER_OPTIONS_OFFSET] & JUNIPER_ETHER_L2PRESENT) != JUNIPER_ETHER_L2PRESENT) {
        tcpedit_seterr(ctx->tcpedit, "Frame is missing L2 Header: %x", packet[JUNIPER_ETHER_OPTIONS_OFFSET]);
        return NULL;
    }

    l2len = dlt_jnpr_ether_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_jnpr_ether_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_jnpr_ether_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 a static pointer to the source/destination MAC address
 * return NULL on error/address doesn't exist
 */
u_char *
dlt_jnpr_ether_get_mac(tcpeditdlt_t *ctx, tcpeditdlt_mac_type_t mac, const u_char *packet, int pktlen)
{
    const u_char *ethernet = NULL;
    jnpr_ether_config_t *config;
    int jnpr_hdr_len = 0;

    assert(ctx);
    assert(packet);

    if (pktlen < JUNIPER_ETHER_EXTLEN_OFFSET + 2)
        return NULL;

    config = (jnpr_ether_config_t *)ctx->encoder->config;

    /* first get the Juniper header length */
    memcpy(&jnpr_hdr_len, &packet[JUNIPER_ETHER_EXTLEN_OFFSET], 2);

    jnpr_hdr_len = ntohs(jnpr_hdr_len) + JUNIPER_ETHER_HEADER_LEN;
    ethernet = packet + jnpr_hdr_len;

    return dlt_en10mb_get_mac(config->subctx, mac, ethernet, (pktlen - jnpr_hdr_len));
}

/*
 * return the length of the L2 header of the current packet
 */
int
dlt_jnpr_ether_l2len(tcpeditdlt_t *ctx, const u_char *packet, int pktlen)
{
    int len, res;
    jnpr_ether_config_t *config;

    assert(ctx);
    assert(packet);

    if (pktlen < JUNIPER_ETHER_EXTLEN_OFFSET + 2)
        return -1;

    config = (jnpr_ether_config_t *)ctx->encoder->config;

    /* first get the Juniper header length */
    memcpy(&len, &packet[JUNIPER_ETHER_EXTLEN_OFFSET], 2);

    len = ntohs(len) + JUNIPER_ETHER_HEADER_LEN;
    dbgx(3, "juniper header len: %u", len);

    /* add the 802.3 length */
    res = tcpedit_dlt_l2len(config->subctx, DLT_EN10MB, (packet + len), (pktlen - len));
    if (res == -1)
        return TCPEDIT_ERROR;

    len += res;
    dbgx(3, "total l2len: %u", len);

    /* and return that */
    return len;
}

tcpeditdlt_l2addr_type_t
dlt_jnpr_ether_l2addr_type(void)
{
    return ETHERNET;
}