138 lines
4.2 KiB
C
138 lines
4.2 KiB
C
/**
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* @file DHCPIpUdpDecoder.c
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* @author Ambroz Bizjak <ambrop7@gmail.com>
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*
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* @section LICENSE
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the author nor the
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* names of its contributors may be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <limits.h>
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#include <string.h>
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#include <misc/ipv4_proto.h>
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#include <misc/udp_proto.h>
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#include <misc/byteorder.h>
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#include <dhcpclient/DHCPIpUdpDecoder.h>
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#define DHCP_SERVER_PORT 67
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#define DHCP_CLIENT_PORT 68
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#define IPUDP_HEADER_SIZE (sizeof(struct ipv4_header) + sizeof(struct udp_header))
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static void input_handler_send (DHCPIpUdpDecoder *o, uint8_t *data, int data_len)
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{
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ASSERT(data_len >= 0)
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DebugObject_Access(&o->d_obj);
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struct ipv4_header iph;
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uint8_t *pl;
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int pl_len;
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if (!ipv4_check(data, data_len, &iph, &pl, &pl_len)) {
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goto fail;
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}
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if (ntoh8(iph.protocol) != IPV4_PROTOCOL_UDP) {
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goto fail;
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}
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if (pl_len < sizeof(struct udp_header)) {
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goto fail;
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}
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struct udp_header udph;
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memcpy(&udph, pl, sizeof(udph));
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if (ntoh16(udph.source_port) != DHCP_SERVER_PORT) {
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goto fail;
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}
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if (ntoh16(udph.dest_port) != DHCP_CLIENT_PORT) {
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goto fail;
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}
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int udph_length = ntoh16(udph.length);
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if (udph_length < sizeof(udph)) {
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goto fail;
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}
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if (udph_length > data_len - (pl - data)) {
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goto fail;
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}
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if (ntoh16(udph.checksum) != 0) {
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uint16_t checksum_in_packet = udph.checksum;
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udph.checksum = 0;
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uint16_t checksum_computed = udp_checksum(&udph, pl + sizeof(udph), udph_length - sizeof(udph), iph.source_address, iph.destination_address);
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if (checksum_in_packet != checksum_computed) {
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goto fail;
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}
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}
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// pass payload to output
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PacketPassInterface_Sender_Send(o->output, pl + sizeof(udph), udph_length - sizeof(udph));
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return;
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fail:
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PacketPassInterface_Done(&o->input);
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}
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static void output_handler_done (DHCPIpUdpDecoder *o)
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{
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DebugObject_Access(&o->d_obj);
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PacketPassInterface_Done(&o->input);
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}
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void DHCPIpUdpDecoder_Init (DHCPIpUdpDecoder *o, PacketPassInterface *output, BPendingGroup *pg)
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{
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ASSERT(PacketPassInterface_GetMTU(output) <= INT_MAX - IPUDP_HEADER_SIZE)
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// init arguments
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o->output = output;
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// init output
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PacketPassInterface_Sender_Init(o->output, (PacketPassInterface_handler_done)output_handler_done, o);
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// init input
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PacketPassInterface_Init(&o->input, IPUDP_HEADER_SIZE + PacketPassInterface_GetMTU(o->output), (PacketPassInterface_handler_send)input_handler_send, o, pg);
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DebugObject_Init(&o->d_obj);
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}
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void DHCPIpUdpDecoder_Free (DHCPIpUdpDecoder *o)
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{
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DebugObject_Free(&o->d_obj);
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// free input
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PacketPassInterface_Free(&o->input);
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}
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PacketPassInterface * DHCPIpUdpDecoder_GetInput (DHCPIpUdpDecoder *o)
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{
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DebugObject_Access(&o->d_obj);
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return &o->input;
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}
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