BadVPN – Rev 1
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/**
* @file BArpProbe.c
* @author Ambroz Bizjak <ambrop7@gmail.com>
*
* @section LICENSE
*
* 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 name of the author 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 BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 AUTHOR 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 <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <net/if.h>
#include <net/if_arp.h>
#include <sys/ioctl.h>
#include <linux/filter.h>
#include <misc/debug.h>
#include <misc/byteorder.h>
#include <misc/ethernet_proto.h>
#include <misc/ipv4_proto.h>
#include <misc/udp_proto.h>
#include <misc/get_iface_info.h>
#include <base/BLog.h>
#include "BArpProbe.h"
#include <generated/blog_channel_BArpProbe.h>
#define STATE_INITIAL 1
#define STATE_NOEXIST 2
#define STATE_EXIST 3
#define STATE_EXIST_PANIC 4
static void dgram_handler (BArpProbe *o, int event)
{
DebugObject_Access(&o->d_obj);
BLog(BLOG_ERROR, "packet socket error");
// report error
DEBUGERROR(&o->d_err, o->handler(o->user, BARPPROBE_EVENT_ERROR));
return;
}
static void send_request (BArpProbe *o)
{
if (o->send_sending) {
BLog(BLOG_ERROR, "cannot send packet while another packet is being sent!");
return;
}
// build packet
struct arp_packet *arp = &o->send_packet;
arp->hardware_type = hton16(ARP_HARDWARE_TYPE_ETHERNET);
arp->protocol_type = hton16(ETHERTYPE_IPV4);
arp->hardware_size = hton8(6);
arp->protocol_size = hton8(4);
arp->opcode = hton16(ARP_OPCODE_REQUEST);
memcpy(arp->sender_mac, o->if_mac, 6);
arp->sender_ip = hton32(0);
memset(arp->target_mac, 0, sizeof(arp->target_mac));
arp->target_ip = o->addr;
// send packet
PacketPassInterface_Sender_Send(o->send_if, (uint8_t *)&o->send_packet, sizeof(o->send_packet));
// set sending
o->send_sending = 1;
}
static void send_if_handler_done (BArpProbe *o)
{
DebugObject_Access(&o->d_obj);
ASSERT(o->send_sending)
// set not sending
o->send_sending = 0;
}
static void recv_if_handler_done (BArpProbe *o, int data_len)
{
DebugObject_Access(&o->d_obj);
ASSERT(data_len >= 0)
ASSERT(data_len <= sizeof(struct arp_packet))
// receive next packet
PacketRecvInterface_Receiver_Recv(o->recv_if, (uint8_t *)&o->recv_packet);
if (data_len != sizeof(struct arp_packet)) {
BLog(BLOG_WARNING, "receive: wrong size");
return;
}
struct arp_packet *arp = &o->recv_packet;
if (ntoh16(arp->hardware_type) != ARP_HARDWARE_TYPE_ETHERNET) {
BLog(BLOG_WARNING, "receive: wrong hardware type");
return;
}
if (ntoh16(arp->protocol_type) != ETHERTYPE_IPV4) {
BLog(BLOG_WARNING, "receive: wrong protocol type");
return;
}
if (ntoh8(arp->hardware_size) != 6) {
BLog(BLOG_WARNING, "receive: wrong hardware size");
return;
}
if (ntoh8(arp->protocol_size) != 4) {
BLog(BLOG_WARNING, "receive: wrong protocol size");
return;
}
if (ntoh16(arp->opcode) != ARP_OPCODE_REPLY) {
return;
}
if (arp->sender_ip != o->addr) {
return;
}
int old_state = o->state;
// set minus one missed
o->num_missed = -1;
// set timer
BReactor_SetTimerAfter(o->reactor, &o->timer, BARPPROBE_EXIST_WAITSEND);
// set state exist
o->state = STATE_EXIST;
// report exist if needed
if (old_state == STATE_INITIAL || old_state == STATE_NOEXIST) {
o->handler(o->user, BARPPROBE_EVENT_EXIST);
return;
}
}
static void timer_handler (BArpProbe *o)
{
DebugObject_Access(&o->d_obj);
// send request
send_request(o);
switch (o->state) {
case STATE_INITIAL: {
ASSERT(o->num_missed >= 0)
ASSERT(o->num_missed < BARPPROBE_INITIAL_NUM_ATTEMPTS)
// increment missed
o->num_missed++;
// all attempts failed?
if (o->num_missed == BARPPROBE_INITIAL_NUM_ATTEMPTS) {
// set timer
BReactor_SetTimerAfter(o->reactor, &o->timer, BARPPROBE_NOEXIST_WAITRECV);
// set state noexist
o->state = STATE_NOEXIST;
// report noexist
o->handler(o->user, BARPPROBE_EVENT_NOEXIST);
return;
}
// set timer
BReactor_SetTimerAfter(o->reactor, &o->timer, BARPPROBE_INITIAL_WAITRECV);
} break;
case STATE_NOEXIST: {
// set timer
BReactor_SetTimerAfter(o->reactor, &o->timer, BARPPROBE_NOEXIST_WAITRECV);
} break;
case STATE_EXIST: {
ASSERT(o->num_missed >= -1)
ASSERT(o->num_missed < BARPPROBE_EXIST_NUM_NOREPLY)
// increment missed
o->num_missed++;
// all missed?
if (o->num_missed == BARPPROBE_EXIST_NUM_NOREPLY) {
// set timer
BReactor_SetTimerAfter(o->reactor, &o->timer, BARPPROBE_EXIST_PANIC_WAITRECV);
// set zero missed
o->num_missed = 0;
// set state panic
o->state = STATE_EXIST_PANIC;
return;
}
// set timer
BReactor_SetTimerAfter(o->reactor, &o->timer, BARPPROBE_EXIST_WAITRECV);
} break;
case STATE_EXIST_PANIC: {
ASSERT(o->num_missed >= 0)
ASSERT(o->num_missed < BARPPROBE_EXIST_PANIC_NUM_NOREPLY)
// increment missed
o->num_missed++;
// all missed?
if (o->num_missed == BARPPROBE_EXIST_PANIC_NUM_NOREPLY) {
// set timer
BReactor_SetTimerAfter(o->reactor, &o->timer, BARPPROBE_NOEXIST_WAITRECV);
// set state panic
o->state = STATE_NOEXIST;
// report noexist
o->handler(o->user, BARPPROBE_EVENT_NOEXIST);
return;
}
// set timer
BReactor_SetTimerAfter(o->reactor, &o->timer, BARPPROBE_EXIST_PANIC_WAITRECV);
} break;
}
}
int BArpProbe_Init (BArpProbe *o, const char *ifname, uint32_t addr, BReactor *reactor, void *user, BArpProbe_handler handler)
{
ASSERT(ifname)
ASSERT(handler)
// init arguments
o->addr = addr;
o->reactor = reactor;
o->user = user;
o->handler = handler;
// get interface information
int if_mtu;
int if_index;
if (!badvpn_get_iface_info(ifname, o->if_mac, &if_mtu, &if_index)) {
BLog(BLOG_ERROR, "failed to get interface information");
goto fail0;
}
uint8_t *if_mac = o->if_mac;
BLog(BLOG_INFO, "if_mac=%02"PRIx8":%02"PRIx8":%02"PRIx8":%02"PRIx8":%02"PRIx8":%02"PRIx8" if_mtu=%d if_index=%d",
if_mac[0], if_mac[1], if_mac[2], if_mac[3], if_mac[4], if_mac[5], if_mtu, if_index);
// check MTU
if (if_mtu < sizeof(struct arp_packet)) {
BLog(BLOG_ERROR, "MTU is too small for ARP !?!");
goto fail0;
}
// init dgram
if (!BDatagram_Init(&o->dgram, BADDR_TYPE_PACKET, o->reactor, o, (BDatagram_handler)dgram_handler)) {
BLog(BLOG_ERROR, "BDatagram_Init failed");
goto fail0;
}
// bind dgram
BAddr bind_addr;
BAddr_InitPacket(&bind_addr, hton16(ETHERTYPE_ARP), if_index, BADDR_PACKET_HEADER_TYPE_ETHERNET, BADDR_PACKET_PACKET_TYPE_HOST, if_mac);
if (!BDatagram_Bind(&o->dgram, bind_addr)) {
BLog(BLOG_ERROR, "BDatagram_Bind failed");
goto fail1;
}
// set dgram send addresses
BAddr dest_addr;
uint8_t broadcast_mac[] = {0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
BAddr_InitPacket(&dest_addr, hton16(ETHERTYPE_ARP), if_index, BADDR_PACKET_HEADER_TYPE_ETHERNET, BADDR_PACKET_PACKET_TYPE_BROADCAST, broadcast_mac);
BIPAddr local_addr;
BIPAddr_InitInvalid(&local_addr);
BDatagram_SetSendAddrs(&o->dgram, dest_addr, local_addr);
// init send interface
BDatagram_SendAsync_Init(&o->dgram, sizeof(struct arp_packet));
o->send_if = BDatagram_SendAsync_GetIf(&o->dgram);
PacketPassInterface_Sender_Init(o->send_if, (PacketPassInterface_handler_done)send_if_handler_done, o);
// set not sending
o->send_sending = 0;
// init recv interface
BDatagram_RecvAsync_Init(&o->dgram, sizeof(struct arp_packet));
o->recv_if = BDatagram_RecvAsync_GetIf(&o->dgram);
PacketRecvInterface_Receiver_Init(o->recv_if, (PacketRecvInterface_handler_done)recv_if_handler_done, o);
// init timer
BTimer_Init(&o->timer, 0, (BTimer_handler)timer_handler, o);
// receive first packet
PacketRecvInterface_Receiver_Recv(o->recv_if, (uint8_t *)&o->recv_packet);
// send request
send_request(o);
// set timer
BReactor_SetTimerAfter(o->reactor, &o->timer, BARPPROBE_INITIAL_WAITRECV);
// set zero missed
o->num_missed = 0;
// set state initial
o->state = STATE_INITIAL;
DebugError_Init(&o->d_err, BReactor_PendingGroup(o->reactor));
DebugObject_Init(&o->d_obj);
return 1;
fail1:
BDatagram_Free(&o->dgram);
fail0:
return 0;
}
void BArpProbe_Free (BArpProbe *o)
{
DebugObject_Free(&o->d_obj);
DebugError_Free(&o->d_err);
// free timer
BReactor_RemoveTimer(o->reactor, &o->timer);
// free recv interface
BDatagram_RecvAsync_Free(&o->dgram);
// free send interface
BDatagram_SendAsync_Free(&o->dgram);
// free dgram
BDatagram_Free(&o->dgram);
}