/*
* Copyright (c) 2020-2022, the SerenityOS developers.
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include "DHCPv4Client.h"
#include <AK/Array.h>
#include <AK/Debug.h>
#include <AK/IPv4Address.h>
#include <AK/JsonArray.h>
#include <AK/JsonObject.h>
#include <AK/JsonParser.h>
#include <AK/Random.h>
#include <AK/ScopeGuard.h>
#include <AK/Try.h>
#include <LibCore/File.h>
#include <LibCore/Timer.h>
#include <stdio.h>
static u8 mac_part(Vector<ByteString> const& parts, size_t index)
{
auto result = AK::StringUtils::convert_to_uint_from_hex(parts.at(index));
VERIFY(result.has_value());
return result.value();
}
static MACAddress mac_from_string(ByteString const& str)
{
auto chunks = str.split(':');
VERIFY(chunks.size() == 6); // should we...worry about this?
return {
mac_part(chunks, 0), mac_part(chunks, 1), mac_part(chunks, 2),
mac_part(chunks, 3), mac_part(chunks, 4), mac_part(chunks, 5)
};
}
static bool send(InterfaceDescriptor const& iface, DHCPv4Packet const& packet, Core::EventReceiver*)
{
int fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
if (fd < 0) {
dbgln("ERROR: socket :: {}", strerror(errno));
return false;
}
ScopeGuard socket_close_guard = [&] { close(fd); };
if (setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE, iface.ifname.characters(), IFNAMSIZ) < 0) {
dbgln("ERROR: setsockopt(SO_BINDTODEVICE) :: {}", strerror(errno));
return false;
}
int allow_broadcast = 1;
if (setsockopt(fd, SOL_SOCKET, SO_BROADCAST, &allow_broadcast, sizeof(int)) < 0) {
dbgln("ERROR: setsockopt(SO_BROADCAST) :: {}", strerror(errno));
return false;
}
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));
dbgln_if(DHCPV4CLIENT_DEBUG, "sendto({} bound to {}, ..., {} at {}) = ...?", fd, iface.ifname, dst.sin_addr.s_addr, dst.sin_port);
auto rc = sendto(fd, &packet, sizeof(packet), 0, (sockaddr*)&dst, sizeof(dst));
dbgln_if(DHCPV4CLIENT_DEBUG, "sendto({}) = {}", fd, rc);
if (rc < 0) {
dbgln("sendto failed with {}", strerror(errno));
return false;
}
return true;
}
static void set_params(InterfaceDescriptor const& iface, IPv4Address const& ipv4_addr, IPv4Address const& netmask, Optional<IPv4Address> const& gateway)
{
int fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
if (fd < 0) {
dbgln("ERROR: socket :: {}", strerror(errno));
return;
}
struct ifreq ifr;
memset(&ifr, 0, sizeof(ifr));
bool fits = iface.ifname.copy_characters_to_buffer(ifr.ifr_name, IFNAMSIZ);
if (!fits) {
dbgln("Interface name doesn't fit into IFNAMSIZ!");
return;
}
// 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) {
dbgln("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) {
dbgln("ERROR: ioctl(SIOCSIFNETMASK) :: {}", strerror(errno));
}
if (!gateway.has_value())
return;
// set the default gateway
struct rtentry rt;
memset(&rt, 0, sizeof(rt));
rt.rt_dev = const_cast<char*>(iface.ifname.characters());
rt.rt_gateway.sa_family = AF_INET;
((sockaddr_in&)rt.rt_gateway).sin_addr.s_addr = gateway.value().to_in_addr_t();
rt.rt_flags = RTF_UP | RTF_GATEWAY;
if (ioctl(fd, SIOCADDRT, &rt) < 0) {
dbgln("Error: ioctl(SIOCADDRT) :: {}", strerror(errno));
}
}
DHCPv4Client::DHCPv4Client(Vector<ByteString> interfaces_with_dhcp_enabled)
: m_interfaces_with_dhcp_enabled(move(interfaces_with_dhcp_enabled))
{
m_server = Core::UDPServer::construct(this);
m_server->on_ready_to_receive = [this] {
// TODO: we need to handle possible errors here somehow
auto buffer = MUST(m_server->receive(sizeof(DHCPv4Packet)));
dbgln_if(DHCPV4CLIENT_DEBUG, "Received {} bytes", buffer.size());
if (buffer.size() < sizeof(DHCPv4Packet) - DHCPV4_OPTION_FIELD_MAX_LENGTH + 1 || buffer.size() > sizeof(DHCPv4Packet)) {
dbgln("we expected {}-{} bytes, this is a bad packet", sizeof(DHCPv4Packet) - DHCPV4_OPTION_FIELD_MAX_LENGTH + 1, sizeof(DHCPv4Packet));
return;
}
auto& packet = *(DHCPv4Packet*)buffer.data();
process_incoming(packet);
};
if (!m_server->bind({}, 68)) {
dbgln("The server we just created somehow came already bound, refusing to continue");
VERIFY_NOT_REACHED();
}
m_check_timer = Core::Timer::create_repeating(
1000, [this] { try_discover_ifs(); }, this);
m_check_timer->start();
try_discover_ifs();
}
void DHCPv4Client::try_discover_ifs()
{
auto ifs_result = get_discoverable_interfaces();
if (ifs_result.is_error())
return;
dbgln_if(DHCPV4CLIENT_DEBUG, "Interfaces with DHCP enabled: {}", m_interfaces_with_dhcp_enabled);
bool sent_discover_request = false;
Interfaces& ifs = ifs_result.value();
for (auto& iface : ifs.ready) {
dbgln_if(DHCPV4CLIENT_DEBUG, "Checking interface {} / {}", iface.ifname, iface.current_ip_address);
if (!m_interfaces_with_dhcp_enabled.contains_slow(iface.ifname))
continue;
if (iface.current_ip_address != IPv4Address { 0, 0, 0, 0 })
continue;
dhcp_discover(iface);
sent_discover_request = true;
}
if (sent_discover_request) {
auto current_interval = m_check_timer->interval();
if (current_interval < m_max_timer_backoff_interval)
current_interval *= 1.9f;
m_check_timer->set_interval(current_interval);
} else {
m_check_timer->set_interval(1000);
}
}
ErrorOr<DHCPv4Client::Interfaces> DHCPv4Client::get_discoverable_interfaces()
{
auto file = TRY(Core::File::open("/sys/kernel/net/adapters"sv, Core::File::OpenMode::Read));
auto file_contents = TRY(file->read_until_eof());
auto json = JsonValue::from_string(file_contents);
if (json.is_error() || !json.value().is_array()) {
dbgln("Error: No network adapters available");
return Error::from_string_literal("No network adapters available");
}
Vector<InterfaceDescriptor> ifnames_to_immediately_discover, ifnames_to_attempt_later;
json.value().as_array().for_each([&ifnames_to_immediately_discover, &ifnames_to_attempt_later](auto& value) {
auto if_object = value.as_object();
if (if_object.get_byte_string("class_name"sv).value_or({}) == "LoopbackAdapter")
return;
auto name = if_object.get_byte_string("name"sv).value_or({});
auto mac = if_object.get_byte_string("mac_address"sv).value_or({});
auto is_up = if_object.get_bool("link_up"sv).value_or(false);
auto ipv4_addr_maybe = IPv4Address::from_string(if_object.get_byte_string("ipv4_address"sv).value_or({}));
auto ipv4_addr = ipv4_addr_maybe.has_value() ? ipv4_addr_maybe.value() : IPv4Address { 0, 0, 0, 0 };
if (is_up) {
dbgln_if(DHCPV4_DEBUG, "Found adapter '{}' with mac {}, and it was up!", name, mac);
ifnames_to_immediately_discover.empend(name, mac_from_string(mac), ipv4_addr);
} else {
dbgln_if(DHCPV4_DEBUG, "Found adapter '{}' with mac {}, but it was down", name, mac);
ifnames_to_attempt_later.empend(name, mac_from_string(mac), ipv4_addr);
}
});
return Interfaces {
move(ifnames_to_immediately_discover),
move(ifnames_to_attempt_later)
};
}
void DHCPv4Client::handle_offer(DHCPv4Packet const& packet, ParsedDHCPv4Options const& options)
{
dbgln("We were offered {} for {}", packet.yiaddr().to_byte_string(), options.get<u32>(DHCPOption::IPAddressLeaseTime).value_or(0));
auto* transaction = const_cast<DHCPv4Transaction*>(m_ongoing_transactions.get(packet.xid()).value_or(nullptr));
if (!transaction) {
dbgln("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(DHCPv4Packet const& packet, ParsedDHCPv4Options const& options)
{
if constexpr (DHCPV4CLIENT_DEBUG) {
dbgln("The DHCP server handed us {}", packet.yiaddr().to_byte_string());
dbgln("Here are the options: {}", options.to_byte_string());
}
auto* transaction = const_cast<DHCPv4Transaction*>(m_ongoing_transactions.get(packet.xid()).value_or(nullptr));
if (!transaction) {
dbgln("we're not looking for {}", packet.xid());
return;
}
transaction->has_ip = true;
auto& interface = transaction->interface;
auto new_ip = packet.yiaddr();
interface.current_ip_address = new_ip;
auto lease_time = AK::convert_between_host_and_network_endian(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
(void)Core::Timer::create_single_shot(
lease_time * 1000,
[this, transaction, interface = InterfaceDescriptor { interface }] {
transaction->accepted_offer = false;
transaction->has_ip = false;
dhcp_discover(interface);
},
this);
Optional<IPv4Address> gateway;
if (auto routers = options.get_many<IPv4Address>(DHCPOption::Router, 1); !routers.is_empty())
gateway = routers.first();
set_params(transaction->interface, new_ip, options.get<IPv4Address>(DHCPOption::SubnetMask).value(), gateway);
}
void DHCPv4Client::handle_nak(DHCPv4Packet const& packet, ParsedDHCPv4Options const& options)
{
dbgln("The DHCP server told us to go chase our own tail about {}", packet.yiaddr().to_byte_string());
dbgln("Here are the options: {}", options.to_byte_string());
// make another request a bit later :shrug:
auto* transaction = const_cast<DHCPv4Transaction*>(m_ongoing_transactions.get(packet.xid()).value_or(nullptr));
if (!transaction) {
dbgln("we're not looking for {}", packet.xid());
return;
}
transaction->accepted_offer = false;
transaction->has_ip = false;
auto& iface = transaction->interface;
(void)Core::Timer::create_single_shot(
10000,
[this, iface = InterfaceDescriptor { iface }] {
dhcp_discover(iface);
},
this);
}
void DHCPv4Client::process_incoming(DHCPv4Packet const& packet)
{
auto options = packet.parse_options();
dbgln_if(DHCPV4CLIENT_DEBUG, "Here are the options: {}", options.to_byte_string());
auto value_or_error = options.get<DHCPMessageType>(DHCPOption::DHCPMessageType);
if (!value_or_error.has_value())
return;
auto value = value_or_error.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:
dbgln("I dunno what to do with this {}", (u8)value);
VERIFY_NOT_REACHED();
break;
}
}
void DHCPv4Client::dhcp_discover(InterfaceDescriptor const& iface)
{
auto transaction_id = get_random<u32>();
if constexpr (DHCPV4CLIENT_DEBUG) {
dbgln("Trying to lease an IP for {} with ID {}", iface.ifname, transaction_id);
if (!iface.current_ip_address.is_zero())
dbgln("going to request the server to hand us {}", iface.current_ip_address.to_byte_string());
}
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() = iface.current_ip_address;
packet.set_chaddr(iface.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
if (!send(iface, dhcp_packet, this))
return;
m_ongoing_transactions.set(transaction_id, make<DHCPv4Transaction>(iface));
}
void DHCPv4Client::dhcp_request(DHCPv4Transaction& transaction, DHCPv4Packet const& offer)
{
auto& iface = transaction.interface;
dbgln("Leasing the IP {} for adapter {}", offer.yiaddr().to_byte_string(), iface.ifname);
DHCPv4PacketBuilder builder;
DHCPv4Packet& packet = builder.peek();
packet.set_op(DHCPv4Op::BootRequest);
packet.ciaddr() = iface.current_ip_address;
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.mac_address);
packet.set_secs(65535); // we lie
// set packet options
builder.set_message_type(DHCPMessageType::DHCPRequest);
builder.add_option(DHCPOption::RequestedIPAddress, sizeof(IPv4Address), &offer.yiaddr());
auto maybe_dhcp_server_ip = offer.parse_options().get<IPv4Address>(DHCPOption::ServerIdentifier);
if (maybe_dhcp_server_ip.has_value())
builder.add_option(DHCPOption::ServerIdentifier, sizeof(IPv4Address), &maybe_dhcp_server_ip.value());
AK::Array<DHCPOption, 2> parameter_request_list = {
DHCPOption::SubnetMask,
DHCPOption::Router,
};
builder.add_option(DHCPOption::ParameterRequestList, parameter_request_list.size(), ¶meter_request_list);
auto& dhcp_packet = builder.build();
// broadcast the "request" request
if (!send(iface, dhcp_packet, this))
return;
transaction.accepted_offer = true;
}
