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byteduckbyteduck
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Beginning of dhcpclient service
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‎services/CMakeLists.txt

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@@ -1,4 +1,5 @@
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ADD_COMPILE_OPTIONS(-O2)
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ADD_SUBDIRECTORY(dhcpclient/)
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ADD_SUBDIRECTORY(init/)
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ADD_SUBDIRECTORY(pond/)
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ADD_SUBDIRECTORY(quack/)

‎services/dhcpclient/CMakeLists.txt

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SET(SOURCES main.cpp Client.cpp DHCP.cpp)
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MAKE_PROGRAM(dhcpclient)
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TARGET_LINK_LIBRARIES(dhcpclient libduck)

‎services/dhcpclient/Client.cpp

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/* SPDX-License-Identifier: GPL-3.0-or-later */
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/* Copyright © 2016-2024 Byteduck */
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#include "Client.h"
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#include "DHCP.h"
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#include <unistd.h>
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#include <ifaddrs.h>
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#include <libduck/Log.h>
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using namespace Duck;
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ResultRet<Ptr<Client>> Client::make() {
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// Get interfaces
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std::vector<Interface> interfaces;
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struct ifaddrs* addrs;
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if (getifaddrs(&addrs) < 0)
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return Result(errno);
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struct ifaddrs* cur_addr = addrs;
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while (cur_addr) {
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if (cur_addr->ifa_addr->sa_family != AF_INET || cur_addr->ifa_macaddr->sa_family != AF_MACADDR)
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goto next;
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interfaces.push_back(Interface {
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.name = cur_addr->ifa_name,
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.addr = { *((sockaddr_in*) cur_addr->ifa_addr) },
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.hwaddr = { *((sockaddr_mac*) cur_addr->ifa_macaddr) }
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});
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next:
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cur_addr = cur_addr->ifa_next;
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}
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freeifaddrs(addrs);
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if (interfaces.empty())
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return Result("No interfaces to use");
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// Open socket
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int fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
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if (fd == -1)
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return Result(errno);
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// Bind to port 68
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sockaddr_in addr = IPv4Address(0).as_sockaddr(68);
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if (bind(fd, (sockaddr*) &addr, sizeof(addr)) < 0) {
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close(fd);
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return Result(errno);
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}
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return Ptr<Client>(new Client(fd, interfaces));
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}
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Client::Client(int socket, std::vector<Interface> interfaces):
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m_socket(socket),
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m_interfaces(std::move(interfaces))
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{
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}
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void Client::loop() {
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for (auto& interface : m_interfaces)
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discover(interface);
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DHCPPacket buf;
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while (true) {
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auto nread = recv(m_socket, &buf.raw_packet(), sizeof(RawDHCPPacket), 0);
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if (nread < 0) {
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Duck::Log::errf("Error reading packet: {}", strerror(errno));
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break;
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}
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if (nread != sizeof(RawDHCPPacket)) {
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Duck::Log::errf("Received packet of invalid size: {}", nread);
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continue;
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}
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if (!buf.has_valid_cookie()) {
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Duck::Log::errf("Received packet with invalid magic cookie");
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continue;
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}
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auto type = buf.get_option<uint8_t>(MessageType);
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if (!type.has_value()) {
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Duck::Log::errf("Received packet without message type");
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continue;
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}
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Result res = Result::SUCCESS;
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switch (type.value()) {
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case Ack:
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res = do_ack(buf);
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break;
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case Offer:
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Duck::Log::warnf("Received offer, can't handle this yet");
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break;
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case Nak:
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Duck::Log::warnf("Received nak, can't handle this yet");
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break;
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case Decline:
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Duck::Log::warnf("Was declined DHCP request from {}", buf.raw_packet().siaddr);
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break;
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default:
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break;
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}
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if (res.is_error())
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Duck::Log::errf("{}", res);
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}
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}
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Result Client::discover(const Interface& interface) {
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int txid = rand();
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m_transactions[txid] = {.iface = interface, .id = txid};
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DHCPPacket packet;
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packet.raw_packet().op = DHCPOp::BootPRequest;
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packet.raw_packet().htype = 1;
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packet.raw_packet().hlen = sizeof(MACAddress);
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packet.raw_packet().xid = txid;
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packet.raw_packet().flags = 0x1;
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packet.raw_packet().ciaddr = interface.addr;
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for (int i = 0; i < 6; i++)
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packet.raw_packet().chaddr[i] = interface.hwaddr[i];
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packet.raw_packet().secs = 5000;
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uint8_t msgtype = DHCPMsgType::Discover;
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packet.add_option(MessageType, 1, &msgtype);
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packet.add_option(End, 0, nullptr);
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return send_packet(interface, packet.raw_packet());
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}
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Result Client::send_packet(const Interface& interface, const RawDHCPPacket& packet) {
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const int sockid = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
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if (sockid < 0)
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return errno;
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// Bind to interface
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if (setsockopt(sockid, SOL_SOCKET, SO_BINDTODEVICE, interface.name.c_str(), interface.name.length() + 1) < 0) {
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close(sockid);
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return errno;
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}
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// Set allow broadcast
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const int allow = 1;
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if (setsockopt(sockid, SOL_SOCKET, SO_BROADCAST, &allow, sizeof(int)) < 0) {
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close(sockid);
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return errno;
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}
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sockaddr_in addr = IPv4Address(255, 255, 255, 255).as_sockaddr(67);
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auto res = sendto(sockid, &packet, sizeof(packet), 0, (struct sockaddr*) &addr, sizeof(addr));
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close(sockid);
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if (res < 0)
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return errno;
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return Result::SUCCESS;
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}
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Duck::Result Client::do_ack(const DHCPPacket& packet) {
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Duck::Log::dbgf("Received ack from {}", packet.raw_packet().siaddr);
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auto tx = m_transactions.find(packet.raw_packet().xid);
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if (tx == m_transactions.end())
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return {"Couldn't handle ack: No such transaction"};
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auto subnet = packet.get_option<IPv4Address>(SubnetMask);
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if (!subnet.has_value())
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return {"Couldn't handle ack: Wasn't given a subnet mask"};
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auto gateway = packet.get_option<IPv4Address>(Router);
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return setup_interface(tx->second.iface, packet.raw_packet().yiaddr, subnet.value(), gateway);
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}
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Duck::Result Client::setup_interface(const Client::Interface& interface, const IPv4Address& addr, const IPv4Address& subnet, const std::optional<IPv4Address>& gateway) {
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const int sockid = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
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if (sockid < 0)
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return errno;
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// TODO
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}

‎services/dhcpclient/Client.h

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/* SPDX-License-Identifier: GPL-3.0-or-later */
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/* Copyright © 2016-2024 Byteduck */
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#pragma once
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#include <string>
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#include <vector>
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#include "DHCP.h"
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#include <libduck/Result.h>
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#include <libduck/Object.h>
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#include <sys/socket.h>
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#include <map>
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class Client {
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public:
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static Duck::ResultRet<Duck::Ptr<Client>> make();
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void loop();
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private:
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struct Interface {
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std::string name;
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IPv4Address addr;
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MACAddress hwaddr;
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};
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struct Transaction {
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Interface iface;
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int id;
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};
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Client(int socket, std::vector<Interface> interfaces);
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Duck::Result discover(const Interface& interface);
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Duck::Result send_packet(const Interface& interface, const RawDHCPPacket& packet);
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Duck::Result do_ack(const DHCPPacket& packet);
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Duck::Result setup_interface(const Interface& interface, const IPv4Address& addr, const IPv4Address& subnet, const std::optional<IPv4Address>& gateway);
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std::vector<Interface> m_interfaces;
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int m_socket;
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std::map<int, Transaction> m_transactions;
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};

‎services/dhcpclient/DHCP.cpp

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/* SPDX-License-Identifier: GPL-3.0-or-later */
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/* Copyright © 2016-2024 Byteduck */
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#include "DHCP.h"
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#include <string.h>
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DHCPPacket::DHCPPacket() {
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// Magic cookie
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m_packet.options[0] = 0x63;
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m_packet.options[1] = 0x82;
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m_packet.options[2] = 0x53;
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m_packet.options[3] = 0x63;
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}
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bool DHCPPacket::add_option(DHCPOption option, uint8_t size, const void* data) {
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if (m_options_offset + sizeof(uint8_t) * 2 + size > BOOTP_OPTS_MAXLEN)
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return false;
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m_packet.options[m_options_offset++] = option;
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m_packet.options[m_options_offset++] = size;
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if (data && size) {
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memcpy(&m_packet.options, data, size);
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m_options_offset += size;
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}
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return true;
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}
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bool DHCPPacket::has_valid_cookie() const {
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return m_packet.options[0] == 0x63 && m_packet.options[1] == 0x82 && m_packet.options[2] == 0x53 && m_packet.options[3] == 0x63;
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}
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bool DHCPPacket::get_option(DHCPOption option, size_t size, void* ptr) const {
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size_t offset = 4;
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while (offset < BOOTP_OPTS_MAXLEN) {
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if (!m_packet.options[offset] || !m_packet.options[offset + 1])
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return false;
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if (m_packet.options[offset] == option && m_packet.options[offset + 1] == size) {
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memcpy(ptr, &m_packet.options[offset + 2], size);
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return true;
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}
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offset += m_packet.options[offset + 1] + 2;
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}
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return false;
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}

‎services/dhcpclient/DHCP.h

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/* SPDX-License-Identifier: GPL-3.0-or-later */
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/* Copyright © 2016-2024 Byteduck */
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#pragma once
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#include <kernel/api/endian.h>
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#include <kernel/api/ipv4.h>
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#include <kernel/api/net.h>
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#include <optional>
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enum DHCPMsgType {
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Discover = 1,
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Offer = 2,
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Request = 3,
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Decline = 4,
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Ack = 5,
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Nak = 6,
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Release = 7
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};
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enum DHCPOp {
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BootPRequest = 1,
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BootPReply = 2
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};
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enum DHCPOption {
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Pad = 0,
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SubnetMask = 1,
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TimeOffset = 2,
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Router = 3,
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TimeServer = 4,
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NameServer = 5,
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DomainNameServer = 6,
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LogServer = 7,
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CookieServer = 8,
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LPRServer = 9,
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ImpressServer = 10,
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ResourceLocationServer = 11,
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Hostname = 12,
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BootFileSize = 13,
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MeritDumpFile = 14,
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DomainName = 15,
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SwapServer = 16,
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RootPath = 17,
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ExtensionsPath = 18,
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RequestedIP = 50,
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IPLeaseTime = 51,
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OptionOverload = 52,
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MessageType = 53,
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ServerID = 54,
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ParameterRequestList = 55,
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Message = 56,
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MaximumMessageSize = 57,
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RenewalTime = 58,
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RebindingTime = 59,
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VendorClass = 60,
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ClientID = 61,
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TFTPServerName = 66,
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BootfileName = 67,
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End = 255
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};
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#define BOOTP_OPTS_MAXLEN 312
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struct RawDHCPPacket {
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uint8_t op {0};
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uint8_t htype {0};
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uint8_t hlen {0};
68+
uint8_t hop {0};
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BigEndian<uint32_t> xid {0};
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BigEndian<uint16_t> secs {0};
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BigEndian<uint16_t> flags {0};
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IPv4Address ciaddr {0};
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IPv4Address yiaddr {0};
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IPv4Address siaddr {0};
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IPv4Address giaddr {0};
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uint8_t chaddr[16] { 0 };
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uint8_t sname[64] { 0 };
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uint8_t file[128] { 0 };
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uint8_t options[BOOTP_OPTS_MAXLEN] { 0 };
80+
81+
inline const MACAddress& mac() const { return *((const MACAddress*) &chaddr); }
82+
inline void set_mac(const MACAddress& mac) const { *((MACAddress*) &chaddr) = mac; }
83+
} __attribute__((packed));
84+
85+
class DHCPPacket {
86+
public:
87+
DHCPPacket();
88+
explicit DHCPPacket(const RawDHCPPacket& packet): m_packet(packet) {}
89+
90+
[[nodiscard]] RawDHCPPacket& raw_packet() { return m_packet; }
91+
[[nodiscard]] const RawDHCPPacket& raw_packet() const { return m_packet; }
92+
bool add_option(DHCPOption option, uint8_t size, const void* data);
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template<typename T>
95+
std::optional<T> get_option(DHCPOption option) const {
96+
T ret;
97+
if (get_option(option, sizeof(T), &ret))
98+
return ret;
99+
return std::nullopt;
100+
}
101+
102+
[[nodiscard]] bool has_valid_cookie() const;
103+
104+
private:
105+
bool get_option(DHCPOption option, size_t size, void* ptr) const;
106+
107+
RawDHCPPacket m_packet;
108+
size_t m_options_offset = 4;
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};

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