1 | /* $Id: IPv4Pool.cpp 106061 2024-09-16 14:03:52Z vboxsync $ */
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2 | /** @file
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3 | * DHCP server - A pool of IPv4 addresses.
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4 | */
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5 |
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6 | /*
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7 | * Copyright (C) 2017-2024 Oracle and/or its affiliates.
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8 | *
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9 | * This file is part of VirtualBox base platform packages, as
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10 | * available from https://www.virtualbox.org.
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11 | *
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12 | * This program is free software; you can redistribute it and/or
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13 | * modify it under the terms of the GNU General Public License
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14 | * as published by the Free Software Foundation, in version 3 of the
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15 | * License.
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16 | *
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17 | * This program is distributed in the hope that it will be useful, but
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18 | * WITHOUT ANY WARRANTY; without even the implied warranty of
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19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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20 | * General Public License for more details.
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21 | *
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22 | * You should have received a copy of the GNU General Public License
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23 | * along with this program; if not, see <https://www.gnu.org/licenses>.
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24 | *
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25 | * SPDX-License-Identifier: GPL-3.0-only
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26 | */
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27 |
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28 |
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29 | /*********************************************************************************************************************************
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30 | * Header Files *
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31 | *********************************************************************************************************************************/
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32 | #include "DhcpdInternal.h"
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33 | #include <iprt/errcore.h>
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34 |
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35 | #include "IPv4Pool.h"
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36 |
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37 |
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38 | int IPv4Pool::init(const IPv4Range &aRange) RT_NOEXCEPT
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39 | {
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40 | AssertReturn(aRange.isValid(), VERR_INVALID_PARAMETER);
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41 |
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42 | m_range = aRange;
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43 | try
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44 | {
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45 | m_pool.insert(m_range);
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46 | }
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47 | catch (std::bad_alloc &)
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48 | {
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49 | return VERR_NO_MEMORY;
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50 | }
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51 | return VINF_SUCCESS;
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52 | }
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53 |
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54 |
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55 | int IPv4Pool::init(RTNETADDRIPV4 aFirstAddr, RTNETADDRIPV4 aLastAddr) RT_NOEXCEPT
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56 | {
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57 | return init(IPv4Range(aFirstAddr, aLastAddr));
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58 | }
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59 |
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60 |
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61 | /**
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62 | * Internal worker for inserting a range into the pool of available addresses.
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63 | *
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64 | * @returns IPRT status code (asserted).
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65 | * @param a_Range The range to insert.
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66 | */
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67 | int IPv4Pool::i_insert(const IPv4Range &a_Range) RT_NOEXCEPT
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68 | {
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69 | /*
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70 | * Check preconditions. Asserting because nobody checks the return code.
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71 | */
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72 | AssertReturn(m_range.isValid(), VERR_INVALID_STATE);
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73 | AssertReturn(a_Range.isValid(), VERR_INVALID_PARAMETER);
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74 | AssertReturn(m_range.contains(a_Range), VERR_INVALID_PARAMETER);
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75 |
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76 | /*
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77 | * Check that the incoming range doesn't overlap with existing ranges in the pool.
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78 | */
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79 | it_t itHint = m_pool.upper_bound(IPv4Range(a_Range.LastAddr)); /* successor, insertion hint */
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80 | #if 0 /** @todo r=bird: This code is wrong. It has no end() check for starters. Since the method is
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81 | * only for internal consumption, I've replaced it with a strict build assertion. */
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82 | if (itHint != m_pool.begin())
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83 | {
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84 | it_t prev(itHint);
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85 | --prev;
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86 | if (a_Range.FirstAddr <= prev->LastAddr)
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87 | {
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88 | LogRel(("%08x-%08x conflicts with %08x-%08x\n",
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89 | a_Range.FirstAddr, a_Range.LastAddr,
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90 | prev->FirstAddr, prev->LastAddr));
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91 | return VERR_INVALID_PARAMETER;
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92 | }
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93 | }
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94 | #endif
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95 | #ifdef VBOX_STRICT
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96 | for (it_t it2 = m_pool.begin(); it2 != m_pool.end(); ++it2)
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97 | AssertMsg(it2->LastAddr < a_Range.FirstAddr || it2->FirstAddr > a_Range.LastAddr,
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98 | ("%08RX32-%08RX32 conflicts with %08RX32-%08RX32\n",
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99 | a_Range.FirstAddr, a_Range.LastAddr, it2->FirstAddr, it2->LastAddr));
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100 | #endif
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101 |
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102 | /*
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103 | * No overlaps, insert it.
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104 | */
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105 | try
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106 | {
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107 | m_pool.insert(itHint, a_Range);
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108 | }
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109 | catch (std::bad_alloc &)
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110 | {
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111 | return VERR_NO_MEMORY;
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112 | }
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113 | return VINF_SUCCESS;
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114 | }
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115 |
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116 |
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117 | /**
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118 | * Allocates an available IPv4 address from the pool.
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119 | *
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120 | * @returns Non-zero network order IPv4 address on success, zero address
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121 | * (0.0.0.0) on failure.
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122 | */
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123 | RTNETADDRIPV4 IPv4Pool::allocate()
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124 | {
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125 | RTNETADDRIPV4 RetAddr;
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126 | if (!m_pool.empty())
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127 | {
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128 | /* Grab the first address in the pool: */
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129 | it_t itBeg = m_pool.begin();
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130 | RetAddr.u = RT_H2N_U32(itBeg->FirstAddr);
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131 |
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132 | if (itBeg->FirstAddr == itBeg->LastAddr)
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133 | m_pool.erase(itBeg);
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134 | else
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135 | {
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136 | /* Trim the entry (re-inserting it): */
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137 | IPv4Range trimmed = *itBeg;
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138 | trimmed.FirstAddr += 1;
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139 | Assert(trimmed.FirstAddr <= trimmed.LastAddr);
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140 | m_pool.erase(itBeg);
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141 | try
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142 | {
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143 | m_pool.insert(trimmed);
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144 | }
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145 | catch (std::bad_alloc &)
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146 | {
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147 | /** @todo r=bird: Theortically the insert could fail with a bad_alloc and we'd
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148 | * drop a range of IP address. It would be nice if we could safely modify itBit
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149 | * without having to re-insert it. The author of this code (not bird) didn't
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150 | * seem to think this safe?
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151 | *
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152 | * If we want to play safe and all that, just use a AVLRU32TREE (or AVLRU64TREE
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153 | * if lazy) AVL tree from IPRT. Since we know exactly how it's implemented and
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154 | * works, there will be no uncertanties like this when using it (both here
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155 | * and in the i_insert validation logic). */
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156 | LogRelFunc(("Caught bad_alloc! We're truely buggered now!\n"));
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157 | }
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158 | }
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159 | }
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160 | else
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161 | RetAddr.u = 0;
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162 | return RetAddr;
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163 | }
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164 |
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165 |
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166 | /**
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167 | * Allocate the given address.
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168 | *
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169 | * @returns Success indicator.
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170 | * @param a_Addr The IP address to allocate (network order).
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171 | */
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172 | bool IPv4Pool::allocate(RTNETADDRIPV4 a_Addr)
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173 | {
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174 | /*
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175 | * Find the range containing a_Addr.
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176 | */
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177 | it_t it = m_pool.lower_bound(IPv4Range(a_Addr)); /* candidate range */
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178 | if (it != m_pool.end())
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179 | {
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180 | Assert(RT_N2H_U32(a_Addr.u) <= it->LastAddr); /* by definition of < and lower_bound */
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181 |
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182 | if (it->contains(a_Addr))
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183 | {
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184 | /*
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185 | * Remove a_Addr from the range by way of re-insertion.
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186 | */
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187 | const IPV4HADDR haddr = RT_N2H_U32(a_Addr.u);
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188 | IPV4HADDR first = it->FirstAddr;
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189 | IPV4HADDR last = it->LastAddr;
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190 |
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191 | m_pool.erase(it);
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192 | if (first != last)
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193 | {
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194 | if (haddr == first)
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195 | i_insert(++first, last);
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196 | else if (haddr == last)
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197 | i_insert(first, --last);
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198 | else
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199 | {
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200 | i_insert(first, haddr - 1);
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201 | i_insert(haddr + 1, last);
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202 | }
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203 | }
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204 |
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205 | return true;
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206 | }
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207 | }
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208 | return false;
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209 | }
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