1 files changed, 420 insertions, 0 deletions
diff --git a/src/VBox/NetworkServices/Dhcpd/DHCPD.cpp b/src/VBox/NetworkServices/Dhcpd/DHCPD.cpp
new file mode 100644
index 00000000..d0b3f819
--- /dev/null
+++ b/src/VBox/NetworkServices/Dhcpd/DHCPD.cpp
@@ -0,0 +1,420 @@
+/* $Id: DHCPD.cpp $ */
+/** @file
+ * DHCP server - protocol logic
+ */
+
+/*
+ * Copyright (C) 2017-2023 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 <https://www.gnu.org/licenses>.
+ *
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "DhcpdInternal.h"
+#include "DHCPD.h"
+#include "DhcpOptions.h"
+
+#include <iprt/message.h>
+
+
+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<DhcpServerMessage> 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<DhcpServerMessage> 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<DhcpServerMessage> 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<DhcpServerMessage> 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;
+}