ladybird/Services/DHCPClient/DHCPv4Client.cpp

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/*
* Copyright (c) 2020, The SerenityOS developers.
* 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.
*
* 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 COPYRIGHT HOLDER OR CONTRIBUTORS 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 "DHCPv4Client.h"
#include <AK/ByteBuffer.h>
#include <AK/Function.h>
#include <LibCore/SocketAddress.h>
#include <LibCore/Timer.h>
#include <stdio.h>
//#define DHCPV4CLIENT_DEBUG
static void send(const InterfaceDescriptor& iface, const DHCPv4Packet& packet, Core::Object*)
{
int fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
if (fd < 0) {
dbg() << "ERROR: socket :: " << strerror(errno);
return;
}
if (setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE, iface.m_ifname.characters(), IFNAMSIZ) < 0) {
dbg() << "ERROR: setsockopt(SO_BINDTODEVICE) :: " << strerror(errno);
return;
}
sockaddr_in dst;
memset(&dst, 0, sizeof(dst));
dst.sin_family = AF_INET;
dst.sin_port = htons(67);
dst.sin_addr.s_addr = IPv4Address { 255, 255, 255, 255 }.to_u32();
memset(&dst.sin_zero, 0, sizeof(dst.sin_zero));
auto rc = sendto(fd, &packet, sizeof(packet), 0, (sockaddr*)&dst, sizeof(dst));
if (rc < 0) {
dbg() << "sendto failed with " << strerror(errno);
// FIXME: what do we do here?
}
}
static void set_params(const InterfaceDescriptor& iface, const IPv4Address& ipv4_addr, const IPv4Address& netmask, const IPv4Address& gateway)
{
int fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
if (fd < 0) {
dbg() << "ERROR: socket :: " << strerror(errno);
return;
}
struct ifreq ifr;
memset(&ifr, 0, sizeof(ifr));
strncpy(ifr.ifr_name, iface.m_ifname.characters(), IFNAMSIZ);
// set the IP address
ifr.ifr_addr.sa_family = AF_INET;
((sockaddr_in&)ifr.ifr_addr).sin_addr.s_addr = ipv4_addr.to_in_addr_t();
if (ioctl(fd, SIOCSIFADDR, &ifr) < 0) {
dbg() << "ERROR: ioctl(SIOCSIFADDR) :: " << strerror(errno);
}
// set the network mask
((sockaddr_in&)ifr.ifr_netmask).sin_addr.s_addr = netmask.to_in_addr_t();
if (ioctl(fd, SIOCSIFNETMASK, &ifr) < 0) {
dbg() << "ERROR: ioctl(SIOCSIFNETMASK) :: " << strerror(errno);
}
// set the default gateway
struct rtentry rt;
memset(&rt, 0, sizeof(rt));
rt.rt_dev = const_cast<char*>(iface.m_ifname.characters());
rt.rt_gateway.sa_family = AF_INET;
((sockaddr_in&)rt.rt_gateway).sin_addr.s_addr = gateway.to_in_addr_t();
rt.rt_flags = RTF_UP | RTF_GATEWAY;
if (ioctl(fd, SIOCADDRT, &rt) < 0) {
dbg() << "Error: ioctl(SIOCADDRT) :: " << strerror(errno);
}
}
DHCPv4Client::DHCPv4Client(Vector<InterfaceDescriptor> ifnames)
: m_ifnames(ifnames)
{
m_server = Core::UDPServer::construct(this);
m_server->on_ready_to_receive = [this] {
auto buffer = m_server->receive(sizeof(DHCPv4Packet));
dbg() << "Received " << buffer.size() << " bytes";
if (buffer.size() != sizeof(DHCPv4Packet)) {
dbg() << "we expected " << sizeof(DHCPv4Packet) << " bytes, this is a bad packet";
return;
}
auto& packet = *(DHCPv4Packet*)buffer.data();
process_incoming(packet);
};
if (!m_server->bind({}, 68)) {
dbg() << "The server we just created somehow came already bound, refusing to continue";
ASSERT_NOT_REACHED();
}
for (auto& iface : m_ifnames)
dhcp_discover(iface);
}
DHCPv4Client::~DHCPv4Client()
{
}
void DHCPv4Client::handle_offer(const DHCPv4Packet& packet, const ParsedDHCPv4Options& options)
{
dbg() << "We were offered " << packet.yiaddr().to_string() << " for " << options.get<u32>(DHCPOption::IPAddressLeaseTime).value_or(0);
auto* transaction = const_cast<DHCPv4Transaction*>(m_ongoing_transactions.get(packet.xid()).value_or(nullptr));
if (!transaction) {
dbg() << "we're not looking for " << packet.xid();
return;
}
if (transaction->has_ip)
return;
if (transaction->accepted_offer) {
// we've accepted someone's offer, but they haven't given us an ack
// TODO: maybe record this offer?
return;
}
// TAKE IT...
transaction->offered_lease_time = options.get<u32>(DHCPOption::IPAddressLeaseTime).value();
dhcp_request(*transaction, packet);
}
void DHCPv4Client::handle_ack(const DHCPv4Packet& packet, const ParsedDHCPv4Options& options)
{
#ifdef DHCPV4CLIENT_DEBUG
dbg() << "The DHCP server handed us " << packet.yiaddr().to_string();
dbg() << "Here are the options: " << options.to_string();
#endif
auto* transaction = const_cast<DHCPv4Transaction*>(m_ongoing_transactions.get(packet.xid()).value_or(nullptr));
if (!transaction) {
dbg() << "we're not looking for " << packet.xid();
return;
}
transaction->has_ip = true;
auto& interface = transaction->interface;
auto new_ip = packet.yiaddr();
auto lease_time = convert_between_host_and_network(options.get<u32>(DHCPOption::IPAddressLeaseTime).value_or(transaction->offered_lease_time));
// set a timer for the duration of the lease, we shall renew if needed
Core::Timer::create_single_shot(
lease_time * 1000,
[this, transaction, interface = InterfaceDescriptor { interface }, new_ip] {
transaction->accepted_offer = false;
transaction->has_ip = false;
dhcp_discover(interface, new_ip);
},
this);
set_params(transaction->interface, new_ip, options.get<IPv4Address>(DHCPOption::SubnetMask).value(), options.get_many<IPv4Address>(DHCPOption::Router, 1).first());
}
void DHCPv4Client::handle_nak(const DHCPv4Packet& packet, const ParsedDHCPv4Options& options)
{
dbg() << "The DHCP server told us to go chase our own tail about " << packet.yiaddr().to_string();
dbg() << "Here are the options: " << options.to_string();
// make another request a bit later :shrug:
auto* transaction = const_cast<DHCPv4Transaction*>(m_ongoing_transactions.get(packet.xid()).value_or(nullptr));
if (!transaction) {
dbg() << "we're not looking for " << packet.xid();
return;
}
transaction->accepted_offer = false;
transaction->has_ip = false;
auto& iface = transaction->interface;
Core::Timer::create_single_shot(
10000,
[this, iface = InterfaceDescriptor { iface }] {
dhcp_discover(iface);
},
this);
}
void DHCPv4Client::process_incoming(const DHCPv4Packet& packet)
{
auto options = packet.parse_options();
#ifdef DHCPV4CLIENT_DEBUG
dbg() << "Here are the options: " << options.to_string();
#endif
auto value = options.get<DHCPMessageType>(DHCPOption::DHCPMessageType).value();
switch (value) {
case DHCPMessageType::DHCPOffer:
handle_offer(packet, options);
break;
case DHCPMessageType::DHCPAck:
handle_ack(packet, options);
break;
case DHCPMessageType::DHCPNak:
handle_nak(packet, options);
break;
case DHCPMessageType::DHCPDiscover:
case DHCPMessageType::DHCPRequest:
case DHCPMessageType::DHCPRelease:
// These are not for us
// we're just getting them because there are other people on our subnet
// broadcasting stuff
break;
case DHCPMessageType::DHCPDecline:
default:
dbg() << "I dunno what to do with this " << (u8)value;
ASSERT_NOT_REACHED();
break;
}
}
void DHCPv4Client::dhcp_discover(const InterfaceDescriptor& iface, IPv4Address previous)
{
auto transaction_id = rand();
#ifdef DHCPV4CLIENT_DEBUG
dbg() << "Trying to lease an IP for " << iface.m_ifname << " with ID " << transaction_id;
if (!previous.is_zero())
dbg() << "going to request the server to hand us " << previous.to_string();
#endif
DHCPv4PacketBuilder builder;
DHCPv4Packet& packet = builder.peek();
packet.set_op(DHCPv4Op::BootRequest);
packet.set_htype(1); // 10mb ethernet
packet.set_hlen(sizeof(MACAddress));
packet.set_xid(transaction_id);
packet.set_flags(DHCPv4Flags::Broadcast);
packet.ciaddr() = previous;
packet.set_chaddr(iface.m_mac_address);
packet.set_secs(65535); // we lie
// set packet options
builder.set_message_type(DHCPMessageType::DHCPDiscover);
auto& dhcp_packet = builder.build();
// broadcast the discover request
send(iface, dhcp_packet, this);
m_ongoing_transactions.set(transaction_id, make<DHCPv4Transaction>(iface));
}
void DHCPv4Client::dhcp_request(DHCPv4Transaction& transaction, const DHCPv4Packet& offer)
{
auto& iface = transaction.interface;
dbg() << "Leasing the IP " << offer.yiaddr().to_string() << " for adapter " << iface.m_ifname;
DHCPv4PacketBuilder builder;
DHCPv4Packet& packet = builder.peek();
packet.set_op(DHCPv4Op::BootRequest);
packet.set_htype(1); // 10mb ethernet
packet.set_hlen(sizeof(MACAddress));
packet.set_xid(offer.xid());
packet.set_flags(DHCPv4Flags::Broadcast);
packet.set_chaddr(iface.m_mac_address);
packet.set_secs(65535); // we lie
// set packet options
builder.set_message_type(DHCPMessageType::DHCPRequest);
auto& dhcp_packet = builder.build();
// broadcast the "request" request
send(iface, dhcp_packet, this);
transaction.accepted_offer = true;
}