/* $Id: DHCPD.cpp 96407 2022-08-22 17:43:14Z vboxsync $ */ /** @file * DHCP server - protocol logic */ /* * Copyright (C) 2017-2022 Oracle and/or its affiliates. * * This file is part of VirtualBox base platform packages, as * available from https://www.virtualbox.org. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation, in version 3 of the * License. * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, see . * * SPDX-License-Identifier: GPL-3.0-only */ /********************************************************************************************************************************* * Header Files * *********************************************************************************************************************************/ #include "DhcpdInternal.h" #include "DHCPD.h" #include "DhcpOptions.h" #include DHCPD::DHCPD() : m_pConfig(NULL), m_db() { } /** * Initializes the DHCPD with the given config. * * @returns VBox status code. * @param pConfig The configuration to use. */ int DHCPD::init(const Config *pConfig) RT_NOEXCEPT { Assert(pConfig); AssertReturn(!m_pConfig, VERR_INVALID_STATE); m_pConfig = pConfig; /* Load the lease database, ignoring most issues except being out of memory: */ int rc = m_db.init(pConfig); if (RT_SUCCESS(rc)) { rc = i_loadLeases(); if (rc != VERR_NO_MEMORY) return VINF_SUCCESS; DHCP_LOG_MSG_ERROR(("Ran out of memory loading leases from '%s'. Try rename or delete the file.\n", pConfig->getLeasesFilename().c_str())); } return rc; } /** * Load leases from pConfig->getLeasesFilename(). */ int DHCPD::i_loadLeases() RT_NOEXCEPT { return m_db.loadLeases(m_pConfig->getLeasesFilename()); } /** * Save the current leases to pConfig->getLeasesFilename(), doing expiry first. * * This is called after m_db is updated during a client request, so the on disk * database is always up-to-date. This means it doesn't matter if we're * terminated with extreme prejudice, and it allows Main to look up IP addresses * for VMs. * * @throws nothing */ void DHCPD::i_saveLeases() RT_NOEXCEPT { m_db.expire(); m_db.writeLeases(m_pConfig->getLeasesFilename()); } /** * Process a DHCP client message. * * Called by VBoxNetDhcpd::dhcp4Recv(). * * @returns Pointer to DHCP reply (caller deletes this). NULL if no reply * warranted or we're out of memory. * @param req The client message. * @throws nothing */ DhcpServerMessage *DHCPD::process(DhcpClientMessage &req) RT_NOEXCEPT { /* * Dump the package if release log level 3+1 are enable or if debug logging is * enabled. We don't normally want to do this at the default log level, of course. */ if ((LogRelIs3Enabled() && LogRelIsEnabled()) || LogIsEnabled()) req.dump(); /* * Fend off requests that are not for us. */ OptServerId sid(req); if (sid.present() && sid.value().u != m_pConfig->getIPv4Address().u) { if (req.broadcasted() && req.messageType() == RTNET_DHCP_MT_REQUEST) { LogRel2(("Message is not for us, canceling any pending offer.\n")); m_db.cancelOffer(req); } else LogRel2(("Message is not for us.\n")); return NULL; } /* * Process it. */ DhcpServerMessage *reply = NULL; switch (req.messageType()) { /* * Requests that require server's reply. */ case RTNET_DHCP_MT_DISCOVER: try { reply = i_doDiscover(req); } catch (std::bad_alloc &) { LogRelFunc(("i_doDiscover threw bad_alloc\n")); } break; case RTNET_DHCP_MT_REQUEST: try { reply = i_doRequest(req); } catch (std::bad_alloc &) { LogRelFunc(("i_doRequest threw bad_alloc\n")); } break; case RTNET_DHCP_MT_INFORM: try { reply = i_doInform(req); } catch (std::bad_alloc &) { LogRelFunc(("i_doInform threw bad_alloc\n")); } break; /* * Requests that don't have a reply. */ case RTNET_DHCP_MT_DECLINE: i_doDecline(req); break; case RTNET_DHCP_MT_RELEASE: i_doRelease(req); break; /* * Unexpected or unknown message types. */ case RTNET_DHCP_MT_OFFER: LogRel2(("Ignoring unexpected message of type RTNET_DHCP_MT_OFFER!\n")); break; case RTNET_DHCP_MT_ACK: LogRel2(("Ignoring unexpected message of type RTNET_DHCP_MT_ACK!\n")); break; case RTNET_DHCP_MT_NAC: LogRel2(("Ignoring unexpected message of type RTNET_DHCP_MT_NAC!\n")); break; default: LogRel2(("Ignoring unexpected message of unknown type: %d (%#x)!\n", req.messageType(), req.messageType())); break; } return reply; } /** * Internal helper. * * @throws std::bad_alloc */ DhcpServerMessage *DHCPD::i_createMessage(int type, const DhcpClientMessage &req) { return new DhcpServerMessage(req, type, m_pConfig->getIPv4Address()); } /** * 4.3.1 DHCPDISCOVER message * * When a server receives a DHCPDISCOVER message from a client, the server * chooses a network address for the requesting client. If no address is * available, the server may choose to report the problem to the system * administrator. If an address is available, the new address SHOULD be chosen * as follows: * - The client's current address as recorded in the client's current binding, * ELSE * - The client's previous address as recorded in the client's (now expired or * released) binding, if that address is in the server's pool of available * addresses and not already allocated, ELSE * - The address requested in the 'Requested IP Address' option, if that * address is valid and not already allocated, ELSE * - A new address allocated from the server's pool of available addresses; * the address is selected based on the subnet from which the message was * received (if 'giaddr' is 0) or on the address of the relay agent that * forwarded the message ('giaddr' when not 0). * * ... * * @throws std::bad_alloc */ DhcpServerMessage *DHCPD::i_doDiscover(const DhcpClientMessage &req) { /** @todo * XXX: TODO: Windows iSCSI initiator sends DHCPDISCOVER first and * it has ciaddr filled. Shouldn't let it screw up the normal * lease we already have for that client, but we should probably * reply with a pro-forma offer. */ if (req.ciaddr().u != 0) return NULL; Config::ConfigVec vecConfigs; m_pConfig->getConfigsForClient(vecConfigs, req.clientId(), OptVendorClassId(req), OptUserClassId(req)); Binding *b = m_db.allocateBinding(req, vecConfigs); if (b == NULL) return NULL; std::unique_ptr reply; bool fRapidCommit = OptRapidCommit(req).present(); if (!fRapidCommit) { reply.reset(i_createMessage(RTNET_DHCP_MT_OFFER, req)); if (b->state() < Binding::OFFERED) b->setState(Binding::OFFERED); /** @todo use small lease time internally to quickly free unclaimed offers? */ } else { reply.reset(i_createMessage(RTNET_DHCP_MT_ACK, req)); reply->addOption(OptRapidCommit(true)); b->setState(Binding::ACKED); if (!b->isFixed()) i_saveLeases(); } reply->setYiaddr(b->addr()); reply->addOption(OptLeaseTime(b->leaseTime())); OptParameterRequest optlist(req); optmap_t replyOptions; reply->addOptions(m_pConfig->getOptionsForClient(replyOptions, optlist, vecConfigs)); // reply->maybeUnicast(req); /** @todo XXX: we reject ciaddr != 0 above */ return reply.release(); } /** * 4.3.2 DHCPREQUEST message * * A DHCPREQUEST message may come from a client responding to a DHCPOFFER * message from a server, from a client verifying a previously allocated IP * address or from a client extending the lease on a network address. If the * DHCPREQUEST message contains a 'server identifier' option, the message is in * response to a DHCPOFFER message. Otherwise, the message is a request to * verify or extend an existing lease. If the client uses a 'client identifier' * in a DHCPREQUEST message, it MUST use that same 'client identifier' in all * subsequent messages. If the client included a list of requested parameters in * a DHCPDISCOVER message, it MUST include that list in all subsequent messages. * * ... * * @throws std::bad_alloc */ DhcpServerMessage *DHCPD::i_doRequest(const DhcpClientMessage &req) { OptRequestedAddress reqAddr(req); if (req.ciaddr().u != 0 && reqAddr.present() && reqAddr.value().u != req.ciaddr().u) { std::unique_ptr nak(i_createMessage(RTNET_DHCP_MT_NAC, req)); nak->addOption(OptMessage("Requested address does not match ciaddr")); return nak.release(); } Config::ConfigVec vecConfigs; m_pConfig->getConfigsForClient(vecConfigs, req.clientId(), OptVendorClassId(req), OptUserClassId(req)); Binding *b = m_db.allocateBinding(req, vecConfigs); if (b == NULL) { return i_createMessage(RTNET_DHCP_MT_NAC, req); } std::unique_ptr ack(i_createMessage(RTNET_DHCP_MT_ACK, req)); b->setState(Binding::ACKED); if (!b->isFixed()) i_saveLeases(); ack->setYiaddr(b->addr()); ack->addOption(OptLeaseTime(b->leaseTime())); OptParameterRequest optlist(req); optmap_t replyOptions; ack->addOptions(m_pConfig->getOptionsForClient(replyOptions, optlist, vecConfigs)); ack->maybeUnicast(req); return ack.release(); } /** * 4.3.5 DHCPINFORM message * * The server responds to a DHCPINFORM message by sending a DHCPACK message * directly to the address given in the 'ciaddr' field of the DHCPINFORM * message. The server MUST NOT send a lease expiration time to the client and * SHOULD NOT fill in 'yiaddr'. The server includes other parameters in the * DHCPACK message as defined in section 4.3.1. * * @throws std::bad_alloc */ DhcpServerMessage *DHCPD::i_doInform(const DhcpClientMessage &req) { if (req.ciaddr().u == 0) return NULL; OptParameterRequest optlist(req); if (!optlist.present()) return NULL; Config::ConfigVec vecConfigs; optmap_t info; m_pConfig->getOptionsForClient(info, optlist, m_pConfig->getConfigsForClient(vecConfigs, req.clientId(), OptVendorClassId(req), OptUserClassId(req))); if (info.empty()) return NULL; std::unique_ptr ack(i_createMessage(RTNET_DHCP_MT_ACK, req)); ack->addOptions(info); ack->maybeUnicast(req); return ack.release(); } /** * 4.3.3 DHCPDECLINE message * * If the server receives a DHCPDECLINE message, the client has discovered * through some other means that the suggested network address is already in * use. The server MUST mark the network address as not available and SHOULD * notify the local system administrator of a possible configuration problem. * * @throws nothing */ DhcpServerMessage *DHCPD::i_doDecline(const DhcpClientMessage &req) RT_NOEXCEPT { RT_NOREF(req); return NULL; } /** * 4.3.4 DHCPRELEASE message * * Upon receipt of a DHCPRELEASE message, the server marks the network address * as not allocated. The server SHOULD retain a record of the client's * initialization parameters for possible reuse in response to subsequent * requests from the client. * * @throws nothing */ DhcpServerMessage *DHCPD::i_doRelease(const DhcpClientMessage &req) RT_NOEXCEPT { if (req.ciaddr().u != 0) { bool fReleased = m_db.releaseBinding(req); if (fReleased) i_saveLeases(); } return NULL; }