tor-android/external/badvpn_dns/dhcpclient/DHCPIpUdpDecoder.c

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2015-01-25 11:08:34 +00:00
/**
* @file DHCPIpUdpDecoder.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 <limits.h>
#include <string.h>
#include <misc/ipv4_proto.h>
#include <misc/udp_proto.h>
#include <misc/byteorder.h>
#include <dhcpclient/DHCPIpUdpDecoder.h>
#define DHCP_SERVER_PORT 67
#define DHCP_CLIENT_PORT 68
#define IPUDP_HEADER_SIZE (sizeof(struct ipv4_header) + sizeof(struct udp_header))
static void input_handler_send (DHCPIpUdpDecoder *o, uint8_t *data, int data_len)
{
ASSERT(data_len >= 0)
DebugObject_Access(&o->d_obj);
struct ipv4_header iph;
uint8_t *pl;
int pl_len;
if (!ipv4_check(data, data_len, &iph, &pl, &pl_len)) {
goto fail;
}
if (ntoh8(iph.protocol) != IPV4_PROTOCOL_UDP) {
goto fail;
}
if (pl_len < sizeof(struct udp_header)) {
goto fail;
}
struct udp_header udph;
memcpy(&udph, pl, sizeof(udph));
if (ntoh16(udph.source_port) != DHCP_SERVER_PORT) {
goto fail;
}
if (ntoh16(udph.dest_port) != DHCP_CLIENT_PORT) {
goto fail;
}
int udph_length = ntoh16(udph.length);
if (udph_length < sizeof(udph)) {
goto fail;
}
if (udph_length > data_len - (pl - data)) {
goto fail;
}
if (ntoh16(udph.checksum) != 0) {
uint16_t checksum_in_packet = udph.checksum;
udph.checksum = 0;
uint16_t checksum_computed = udp_checksum(&udph, pl + sizeof(udph), udph_length - sizeof(udph), iph.source_address, iph.destination_address);
if (checksum_in_packet != checksum_computed) {
goto fail;
}
}
// pass payload to output
PacketPassInterface_Sender_Send(o->output, pl + sizeof(udph), udph_length - sizeof(udph));
return;
fail:
PacketPassInterface_Done(&o->input);
}
static void output_handler_done (DHCPIpUdpDecoder *o)
{
DebugObject_Access(&o->d_obj);
PacketPassInterface_Done(&o->input);
}
void DHCPIpUdpDecoder_Init (DHCPIpUdpDecoder *o, PacketPassInterface *output, BPendingGroup *pg)
{
ASSERT(PacketPassInterface_GetMTU(output) <= INT_MAX - IPUDP_HEADER_SIZE)
// init arguments
o->output = output;
// init output
PacketPassInterface_Sender_Init(o->output, (PacketPassInterface_handler_done)output_handler_done, o);
// init input
PacketPassInterface_Init(&o->input, IPUDP_HEADER_SIZE + PacketPassInterface_GetMTU(o->output), (PacketPassInterface_handler_send)input_handler_send, o, pg);
DebugObject_Init(&o->d_obj);
}
void DHCPIpUdpDecoder_Free (DHCPIpUdpDecoder *o)
{
DebugObject_Free(&o->d_obj);
// free input
PacketPassInterface_Free(&o->input);
}
PacketPassInterface * DHCPIpUdpDecoder_GetInput (DHCPIpUdpDecoder *o)
{
DebugObject_Access(&o->d_obj);
return &o->input;
}