| 1 | /* $Id: DHCPD.cpp 79563 2019-07-06 01:22:56Z vboxsync $ */
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| 2 | /** @file
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| 3 | * DHCP server - protocol logic
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| 4 | */
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| 5 |
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| 6 | /*
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| 7 | * Copyright (C) 2017-2019 Oracle Corporation
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| 8 | *
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| 9 | * This file is part of VirtualBox Open Source Edition (OSE), as
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| 10 | * available from http://www.alldomusa.eu.org. This file is free software;
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| 11 | * you can redistribute it and/or modify it under the terms of the GNU
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| 12 | * General Public License (GPL) as published by the Free Software
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| 13 | * Foundation, in version 2 as it comes in the "COPYING" file of the
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| 14 | * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
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| 15 | * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
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| 16 | */
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| 17 |
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| 18 |
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| 19 | /*********************************************************************************************************************************
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| 20 | * Header Files *
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| 21 | *********************************************************************************************************************************/
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| 22 | #include "DhcpdInternal.h"
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| 23 | #include "DHCPD.h"
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| 24 | #include "DhcpOptions.h"
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| 25 |
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| 26 | #include <iprt/message.h>
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| 27 | #include <iprt/cpp/path.h>
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| 28 |
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| 29 |
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| 30 | DHCPD::DHCPD()
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| 31 | : m_pConfig(NULL), m_db()
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| 32 | {
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| 33 | }
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| 34 |
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| 35 |
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| 36 | /**
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| 37 | * Initializes the DHCPD with the given config.
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| 38 | *
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| 39 | * @returns VBox status code.
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| 40 | * @param pConfig The configuration to use.
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| 41 | */
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| 42 | int DHCPD::init(const Config *pConfig) RT_NOEXCEPT
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| 43 | {
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| 44 | Assert(pConfig);
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| 45 | AssertReturn(!m_pConfig, VERR_INVALID_STATE);
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| 46 |
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| 47 | /** @todo r=bird: This must be configurable so main can read the database and
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| 48 | * fish assignments out of it. (That's the most efficient and accurate way of
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| 49 | * figuring out the IP address of a VM.) */
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| 50 |
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| 51 | /* leases filename */
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| 52 | int rc = m_strLeasesFilename.assignNoThrow(pConfig->getHome());
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| 53 | if (RT_SUCCESS(rc))
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| 54 | rc = RTPathAppendCxx(m_strLeasesFilename, pConfig->getBaseName());
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| 55 | if (RT_SUCCESS(rc))
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| 56 | rc = m_strLeasesFilename.appendNoThrow("-Dhcpd.leases");
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| 57 | if (RT_SUCCESS(rc))
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| 58 | {
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| 59 | /* Load the lease database, ignoring most issues except being out of memory: */
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| 60 | rc = m_db.init(pConfig);
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| 61 | if (RT_SUCCESS(rc))
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| 62 | {
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| 63 | rc = i_loadLeases();
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| 64 | if (rc != VERR_NO_MEMORY)
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| 65 | {
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| 66 | m_pConfig = pConfig;
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| 67 | rc = VINF_SUCCESS;
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| 68 | }
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| 69 | else
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| 70 | {
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| 71 | LogRel(("Ran out of memory loading leases from '%s'. Try rename or delete the file.\n",
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| 72 | m_strLeasesFilename.c_str()));
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| 73 | RTMsgError("Ran out of memory loading leases from '%s'. Try rename or delete the file.\n",
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| 74 | m_strLeasesFilename.c_str());
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| 75 | }
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| 76 | }
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| 77 | }
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| 78 | return rc;
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| 79 | }
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| 80 |
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| 81 |
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| 82 | /**
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| 83 | * Load leases from m_strLeasesFilename.
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| 84 | */
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| 85 | int DHCPD::i_loadLeases() RT_NOEXCEPT
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| 86 | {
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| 87 | return m_db.loadLeases(m_strLeasesFilename);
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| 88 | }
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| 89 |
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| 90 |
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| 91 | /**
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| 92 | * Save the current leases to m_strLeasesFilename, doing expiry first.
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| 93 | *
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| 94 | * This is called after m_db is updated during a client request, so the on disk
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| 95 | * database is always up-to-date. This means it doesn't matter if we're
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| 96 | * terminated with extreme prejudice, and it allows Main to look up IP addresses
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| 97 | * for VMs.
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| 98 | *
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| 99 | * @throws nothing
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| 100 | */
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| 101 | void DHCPD::i_saveLeases() RT_NOEXCEPT
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| 102 | {
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| 103 | m_db.expire();
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| 104 | m_db.writeLeases(m_strLeasesFilename);
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| 105 | }
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| 106 |
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| 107 |
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| 108 | /**
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| 109 | * Process a DHCP client message.
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| 110 | *
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| 111 | * Called by VBoxNetDhcpd::dhcp4Recv().
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| 112 | *
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| 113 | * @returns Pointer to DHCP reply (caller deletes this). NULL if no reply
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| 114 | * warranted or we're out of memory.
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| 115 | * @param req The client message.
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| 116 | * @throws nothing
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| 117 | */
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| 118 | DhcpServerMessage *DHCPD::process(DhcpClientMessage &req) RT_NOEXCEPT
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| 119 | {
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| 120 | /*
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| 121 | * Dump the package if release log level 3+1 are enable or if debug logging is
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| 122 | * enabled. We don't normally want to do this at the default log level, of course.
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| 123 | */
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| 124 | if ((LogRelIs3Enabled() && LogRelIsEnabled()) || LogIsEnabled())
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| 125 | req.dump();
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| 126 |
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| 127 | /*
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| 128 | * Fend off requests that are not for us.
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| 129 | */
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| 130 | OptServerId sid(req);
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| 131 | if (sid.present() && sid.value().u != m_pConfig->getIPv4Address().u)
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| 132 | {
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| 133 | if (req.broadcasted() && req.messageType() == RTNET_DHCP_MT_REQUEST)
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| 134 | {
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| 135 | LogRel2(("Message is not for us, canceling any pending offer.\n"));
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| 136 | m_db.cancelOffer(req);
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| 137 | }
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| 138 | else
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| 139 | LogRel2(("Message is not for us.\n"));
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| 140 | return NULL;
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| 141 | }
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| 142 |
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| 143 | /*
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| 144 | * Process it.
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| 145 | */
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| 146 | DhcpServerMessage *reply = NULL;
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| 147 |
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| 148 | switch (req.messageType())
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| 149 | {
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| 150 | /*
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| 151 | * Requests that require server's reply.
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| 152 | */
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| 153 | case RTNET_DHCP_MT_DISCOVER:
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| 154 | try
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| 155 | {
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| 156 | reply = i_doDiscover(req);
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| 157 | }
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| 158 | catch (std::bad_alloc &)
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| 159 | {
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| 160 | LogRelFunc(("i_doDiscover threw bad_alloc\n"));
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| 161 | }
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| 162 | break;
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| 163 |
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| 164 | case RTNET_DHCP_MT_REQUEST:
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| 165 | try
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| 166 | {
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| 167 | reply = i_doRequest(req);
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| 168 | }
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| 169 | catch (std::bad_alloc &)
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| 170 | {
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| 171 | LogRelFunc(("i_doRequest threw bad_alloc\n"));
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| 172 | }
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| 173 | break;
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| 174 |
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| 175 | case RTNET_DHCP_MT_INFORM:
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| 176 | try
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| 177 | {
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| 178 | reply = i_doInform(req);
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| 179 | }
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| 180 | catch (std::bad_alloc &)
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| 181 | {
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| 182 | LogRelFunc(("i_doInform threw bad_alloc\n"));
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| 183 | }
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| 184 | break;
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| 185 |
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| 186 | /*
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| 187 | * Requests that don't have a reply.
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| 188 | */
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| 189 | case RTNET_DHCP_MT_DECLINE:
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| 190 | i_doDecline(req);
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| 191 | break;
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| 192 |
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| 193 | case RTNET_DHCP_MT_RELEASE:
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| 194 | i_doRelease(req);
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| 195 | break;
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| 196 |
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| 197 | /*
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| 198 | * Unexpected or unknown message types.
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| 199 | */
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| 200 | case RTNET_DHCP_MT_OFFER:
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| 201 | LogRel2(("Ignoring unexpected message of type RTNET_DHCP_MT_OFFER!\n"));
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| 202 | break;
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| 203 | case RTNET_DHCP_MT_ACK:
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| 204 | LogRel2(("Ignoring unexpected message of type RTNET_DHCP_MT_ACK!\n"));
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| 205 | break;
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| 206 | case RTNET_DHCP_MT_NAC:
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| 207 | LogRel2(("Ignoring unexpected message of type RTNET_DHCP_MT_NAC!\n"));
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| 208 | break;
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| 209 | default:
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| 210 | LogRel2(("Ignoring unexpected message of unknown type: %d (%#x)!\n", req.messageType(), req.messageType()));
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| 211 | break;
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| 212 | }
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| 213 |
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| 214 | return reply;
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| 215 | }
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| 216 |
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| 217 |
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| 218 | /**
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| 219 | * Internal helper.
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| 220 | *
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| 221 | * @throws std::bad_alloc
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| 222 | */
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| 223 | DhcpServerMessage *DHCPD::i_createMessage(int type, DhcpClientMessage &req)
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| 224 | {
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| 225 | return new DhcpServerMessage(req, type, m_pConfig->getIPv4Address());
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| 226 | }
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| 227 |
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| 228 |
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| 229 | /**
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| 230 | * 4.3.1 DHCPDISCOVER message
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| 231 | *
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| 232 | * When a server receives a DHCPDISCOVER message from a client, the server
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| 233 | * chooses a network address for the requesting client. If no address is
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| 234 | * available, the server may choose to report the problem to the system
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| 235 | * administrator. If an address is available, the new address SHOULD be chosen
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| 236 | * as follows:
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| 237 | * - The client's current address as recorded in the client's current binding,
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| 238 | * ELSE
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| 239 | * - The client's previous address as recorded in the client's (now expired or
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| 240 | * released) binding, if that address is in the server's pool of available
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| 241 | * addresses and not already allocated, ELSE
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| 242 | * - The address requested in the 'Requested IP Address' option, if that
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| 243 | * address is valid and not already allocated, ELSE
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| 244 | * - A new address allocated from the server's pool of available addresses;
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| 245 | * the address is selected based on the subnet from which the message was
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| 246 | * received (if 'giaddr' is 0) or on the address of the relay agent that
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| 247 | * forwarded the message ('giaddr' when not 0).
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| 248 | *
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| 249 | * ...
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| 250 | *
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| 251 | * @throws std::bad_alloc
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| 252 | */
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| 253 | DhcpServerMessage *DHCPD::i_doDiscover(DhcpClientMessage &req)
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| 254 | {
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| 255 | /** @todo
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| 256 | * XXX: TODO: Windows iSCSI initiator sends DHCPDISCOVER first and
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| 257 | * it has ciaddr filled. Shouldn't let it screw up the normal
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| 258 | * lease we already have for that client, but we should probably
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| 259 | * reply with a pro-forma offer.
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| 260 | */
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| 261 | if (req.ciaddr().u != 0)
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| 262 | return NULL;
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| 263 |
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| 264 | Binding *b = m_db.allocateBinding(req);
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| 265 | if (b == NULL)
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| 266 | return NULL;
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| 267 |
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| 268 | std::unique_ptr<DhcpServerMessage> reply;
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| 269 |
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| 270 | bool fRapidCommit = OptRapidCommit(req).present();
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| 271 | if (!fRapidCommit)
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| 272 | {
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| 273 | reply.reset(i_createMessage(RTNET_DHCP_MT_OFFER, req));
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| 274 |
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| 275 | if (b->state() < Binding::OFFERED)
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| 276 | b->setState(Binding::OFFERED);
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| 277 |
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| 278 | /** @todo use small lease time internally to quickly free unclaimed offers? */
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| 279 | }
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| 280 | else
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| 281 | {
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| 282 | reply.reset(i_createMessage(RTNET_DHCP_MT_ACK, req));
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| 283 | reply->addOption(OptRapidCommit(true));
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| 284 |
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| 285 | b->setState(Binding::ACKED);
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| 286 | i_saveLeases();
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| 287 | }
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| 288 |
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| 289 | reply->setYiaddr(b->addr());
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| 290 | reply->addOption(OptLeaseTime(b->leaseTime()));
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| 291 |
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| 292 |
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| 293 | OptParameterRequest optlist(req);
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| 294 | optmap_t replyOptions;
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| 295 | reply->addOptions(m_pConfig->getOptions(replyOptions, optlist, req.clientId()));
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| 296 |
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| 297 | // reply->maybeUnicast(req); /** @todo XXX: we reject ciaddr != 0 above */
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| 298 | return reply.release();
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| 299 | }
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| 300 |
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| 301 |
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| 302 | /**
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| 303 | * 4.3.2 DHCPREQUEST message
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| 304 | *
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| 305 | * A DHCPREQUEST message may come from a client responding to a DHCPOFFER
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| 306 | * message from a server, from a client verifying a previously allocated IP
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| 307 | * address or from a client extending the lease on a network address. If the
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| 308 | * DHCPREQUEST message contains a 'server identifier' option, the message is in
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| 309 | * response to a DHCPOFFER message. Otherwise, the message is a request to
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| 310 | * verify or extend an existing lease. If the client uses a 'client identifier'
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| 311 | * in a DHCPREQUEST message, it MUST use that same 'client identifier' in all
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| 312 | * subsequent messages. If the client included a list of requested parameters in
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| 313 | * a DHCPDISCOVER message, it MUST include that list in all subsequent messages.
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| 314 | *
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| 315 | * ...
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| 316 | *
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| 317 | * @throws std::bad_alloc
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| 318 | */
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| 319 | DhcpServerMessage *DHCPD::i_doRequest(DhcpClientMessage &req)
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| 320 | {
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| 321 | OptRequestedAddress reqAddr(req);
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| 322 | if (req.ciaddr().u != 0 && reqAddr.present() && reqAddr.value().u != req.ciaddr().u)
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| 323 | {
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| 324 | std::unique_ptr<DhcpServerMessage> nak (
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| 325 | i_createMessage(RTNET_DHCP_MT_NAC, req)
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| 326 | );
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| 327 | nak->addOption(OptMessage("Requested address does not match ciaddr"));
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| 328 | return nak.release();
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| 329 | }
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| 330 |
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| 331 |
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| 332 | Binding *b = m_db.allocateBinding(req);
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| 333 | if (b == NULL)
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| 334 | {
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| 335 | return i_createMessage(RTNET_DHCP_MT_NAC, req);
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| 336 | }
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| 337 |
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| 338 |
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| 339 | std::unique_ptr<DhcpServerMessage> ack(i_createMessage(RTNET_DHCP_MT_ACK, req));
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| 340 |
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| 341 | b->setState(Binding::ACKED);
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| 342 | i_saveLeases();
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| 343 |
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| 344 | ack->setYiaddr(b->addr());
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| 345 | ack->addOption(OptLeaseTime(b->leaseTime()));
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| 346 |
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| 347 | OptParameterRequest optlist(req);
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| 348 | optmap_t replyOptions;
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| 349 | ack->addOptions(m_pConfig->getOptions(replyOptions, optlist, req.clientId()));
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| 350 |
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| 351 | ack->addOption(OptMessage("Ok, ok, here it is"));
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| 352 |
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| 353 | ack->maybeUnicast(req);
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| 354 | return ack.release();
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| 355 | }
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| 356 |
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| 357 |
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| 358 | /**
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| 359 | * 4.3.5 DHCPINFORM message
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| 360 | *
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| 361 | * The server responds to a DHCPINFORM message by sending a DHCPACK message
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| 362 | * directly to the address given in the 'ciaddr' field of the DHCPINFORM
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| 363 | * message. The server MUST NOT send a lease expiration time to the client and
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| 364 | * SHOULD NOT fill in 'yiaddr'. The server includes other parameters in the
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| 365 | * DHCPACK message as defined in section 4.3.1.
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| 366 | *
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| 367 | * @throws std::bad_alloc
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| 368 | */
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| 369 | DhcpServerMessage *DHCPD::i_doInform(DhcpClientMessage &req)
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| 370 | {
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| 371 | if (req.ciaddr().u == 0)
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| 372 | return NULL;
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| 373 |
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| 374 | const OptParameterRequest params(req);
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| 375 | if (!params.present())
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| 376 | return NULL;
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| 377 |
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| 378 | optmap_t info;
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| 379 | m_pConfig->getOptions(info, params, req.clientId());
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| 380 | if (info.empty())
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| 381 | return NULL;
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| 382 |
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| 383 | std::unique_ptr<DhcpServerMessage> ack(i_createMessage(RTNET_DHCP_MT_ACK, req));
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| 384 | ack->addOptions(info);
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| 385 | ack->maybeUnicast(req);
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| 386 | return ack.release();
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| 387 | }
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| 388 |
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| 389 |
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| 390 | /**
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| 391 | * 4.3.3 DHCPDECLINE message
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| 392 | *
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| 393 | * If the server receives a DHCPDECLINE message, the client has discovered
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| 394 | * through some other means that the suggested network address is already in
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| 395 | * use. The server MUST mark the network address as not available and SHOULD
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| 396 | * notify the local system administrator of a possible configuration problem.
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| 397 | *
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| 398 | * @throws nothing
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| 399 | */
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| 400 | DhcpServerMessage *DHCPD::i_doDecline(const DhcpClientMessage &req) RT_NOEXCEPT
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| 401 | {
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| 402 | RT_NOREF(req);
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| 403 | return NULL;
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| 404 | }
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| 405 |
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| 406 |
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| 407 | /**
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| 408 | * 4.3.4 DHCPRELEASE message
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| 409 | *
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| 410 | * Upon receipt of a DHCPRELEASE message, the server marks the network address
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| 411 | * as not allocated. The server SHOULD retain a record of the client's
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| 412 | * initialization parameters for possible reuse in response to subsequent
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| 413 | * requests from the client.
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| 414 | *
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| 415 | * @throws nothing
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| 416 | */
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| 417 | DhcpServerMessage *DHCPD::i_doRelease(const DhcpClientMessage &req) RT_NOEXCEPT
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| 418 | {
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| 419 | if (req.ciaddr().u != 0)
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| 420 | {
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| 421 | bool fReleased = m_db.releaseBinding(req);
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| 422 | if (fReleased)
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| 423 | i_saveLeases();
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|---|
| 424 | }
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|---|
| 425 |
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|---|
| 426 | return NULL;
|
|---|
| 427 | }
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|---|
