badvpn/dhcpclient/DHCPIpUdpEncoder.c

/**
 * @file DHCPIpUdpEncoder.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 <stddef.h>

#include <misc/ipv4_proto.h>
#include <misc/udp_proto.h>
#include <misc/byteorder.h>

#include <dhcpclient/DHCPIpUdpEncoder.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 output_handler_recv (DHCPIpUdpEncoder *o, uint8_t *data)
{
    DebugObject_Access(&o->d_obj);
    
    // remember output packet
    o->data = data;
    
    // receive payload
    PacketRecvInterface_Receiver_Recv(o->input, o->data + IPUDP_HEADER_SIZE);
}

static void input_handler_done (DHCPIpUdpEncoder *o, int data_len)
{
    DebugObject_Access(&o->d_obj);
    
    // build IP header
    struct ipv4_header iph;
    iph.version4_ihl4 = IPV4_MAKE_VERSION_IHL(sizeof(iph));
    iph.ds = hton8(0);
    iph.total_length = hton16(IPUDP_HEADER_SIZE + data_len);
    iph.identification = hton16(0);
    iph.flags3_fragmentoffset13 = hton16(0);
    iph.ttl = hton8(64);
    iph.protocol = hton8(IPV4_PROTOCOL_UDP);
    iph.checksum = hton16(0);
    iph.source_address = hton32(0x00000000);
    iph.destination_address = hton32(0xFFFFFFFF);
    iph.checksum = ipv4_checksum(&iph, NULL, 0);
    
    // write UDP header
    struct udp_header udph;
    udph.source_port = hton16(DHCP_CLIENT_PORT);
    udph.dest_port = hton16(DHCP_SERVER_PORT);
    udph.length = hton16(sizeof(udph) + data_len);
    udph.checksum = hton16(0);
    udph.checksum = udp_checksum(&udph, o->data + IPUDP_HEADER_SIZE, data_len, iph.source_address, iph.destination_address);
    
    // write header
    memcpy(o->data, &iph, sizeof(iph));
    memcpy(o->data + sizeof(iph), &udph, sizeof(udph));
    
    // finish packet
    PacketRecvInterface_Done(&o->output, IPUDP_HEADER_SIZE + data_len);
}

void DHCPIpUdpEncoder_Init (DHCPIpUdpEncoder *o, PacketRecvInterface *input, BPendingGroup *pg)
{
    ASSERT(PacketRecvInterface_GetMTU(input) <= INT_MAX - IPUDP_HEADER_SIZE)
    
    // init arguments
    o->input = input;
    
    // init input
    PacketRecvInterface_Receiver_Init(o->input, (PacketRecvInterface_handler_done)input_handler_done, o);
    
    // init output
    PacketRecvInterface_Init(&o->output, IPUDP_HEADER_SIZE + PacketRecvInterface_GetMTU(o->input), (PacketRecvInterface_handler_recv)output_handler_recv, o, pg);
    
    DebugObject_Init(&o->d_obj);
}

void DHCPIpUdpEncoder_Free (DHCPIpUdpEncoder *o)
{
    DebugObject_Free(&o->d_obj);
    
    // free output
    PacketRecvInterface_Free(&o->output);
}

PacketRecvInterface * DHCPIpUdpEncoder_GetOutput (DHCPIpUdpEncoder *o)
{
    DebugObject_Access(&o->d_obj);
    
    return &o->output;
}