1 | /* $Id: ip_output.c 98103 2023-01-17 14:15:46Z vboxsync $ */
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2 | /** @file
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3 | * NAT - IP output.
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4 | */
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5 |
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6 | /*
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7 | * Copyright (C) 2006-2023 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 | * This code is based on:
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30 | *
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31 | * Copyright (c) 1982, 1986, 1988, 1990, 1993
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32 | * The Regents of the University of California. All rights reserved.
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33 | *
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34 | * Redistribution and use in source and binary forms, with or without
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35 | * modification, are permitted provided that the following conditions
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36 | * are met:
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37 | * 1. Redistributions of source code must retain the above copyright
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38 | * notice, this list of conditions and the following disclaimer.
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39 | * 2. Redistributions in binary form must reproduce the above copyright
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40 | * notice, this list of conditions and the following disclaimer in the
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41 | * documentation and/or other materials provided with the distribution.
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42 | * 3. Neither the name of the University nor the names of its contributors
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43 | * may be used to endorse or promote products derived from this software
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44 | * without specific prior written permission.
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45 | *
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46 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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47 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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48 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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49 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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50 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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51 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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52 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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53 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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54 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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55 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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56 | * SUCH DAMAGE.
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57 | *
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58 | * @(#)ip_output.c 8.3 (Berkeley) 1/21/94
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59 | * ip_output.c,v 1.9 1994/11/16 10:17:10 jkh Exp
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60 | */
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61 |
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62 | /*
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63 | * Changes and additions relating to SLiRP are
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64 | * Copyright (c) 1995 Danny Gasparovski.
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65 | *
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66 | * Please read the file COPYRIGHT for the
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67 | * terms and conditions of the copyright.
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68 | */
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69 |
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70 | #include <slirp.h>
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71 | #include <iprt/errcore.h>
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72 | #include "alias.h"
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73 |
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74 | static const uint8_t broadcast_ethaddr[6] =
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75 | {
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76 | 0xff, 0xff, 0xff, 0xff, 0xff, 0xff
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77 | };
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78 |
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79 | static int rt_lookup_in_cache(PNATState pData, uint32_t dst, uint8_t *ether)
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80 | {
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81 | int rc;
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82 | LogFlowFunc(("ENTER: dst:%RTnaipv4, ether:%RTmac\n", dst, ether));
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83 | if (dst == INADDR_BROADCAST)
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84 | {
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85 | memcpy(ether, broadcast_ethaddr, ETH_ALEN);
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86 | LogFlowFunc(("LEAVE: VINF_SUCCESS\n"));
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87 | return VINF_SUCCESS;
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88 | }
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89 |
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90 | rc = slirp_arp_lookup_ether_by_ip(pData, dst, ether);
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91 | if (RT_SUCCESS(rc))
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92 | {
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93 | LogFlowFunc(("LEAVE: %Rrc\n", rc));
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94 | return rc;
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95 | }
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96 |
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97 | rc = bootp_cache_lookup_ether_by_ip(pData, dst, ether);
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98 | if (RT_SUCCESS(rc))
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99 | {
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100 | LogFlowFunc(("LEAVE: %Rrc\n", rc));
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101 | return rc;
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102 | }
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103 | /*
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104 | * no chance to send this packet, sorry, we will request ether address via ARP
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105 | */
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106 | slirp_arp_who_has(pData, dst);
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107 | LogFlowFunc(("LEAVE: VERR_NOT_FOUND\n"));
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108 | return VERR_NOT_FOUND;
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109 | }
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110 |
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111 | /*
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112 | * IP output. The packet in mbuf chain m contains a skeletal IP
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113 | * header (with len, off, ttl, proto, tos, src, dst).
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114 | * The mbuf chain containing the packet will be freed.
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115 | * The mbuf opt, if present, will not be freed.
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116 | */
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117 | int
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118 | ip_output(PNATState pData, struct socket *so, struct mbuf *m0)
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119 | {
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120 | return ip_output0(pData, so, m0, 0);
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121 | }
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122 |
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123 | /* This function will free m0! */
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124 | int
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125 | ip_output0(PNATState pData, struct socket *so, struct mbuf *m0, int urg)
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126 | {
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127 | register struct ip *ip;
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128 | register struct mbuf *m = m0;
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129 | register int hlen = sizeof(struct ip);
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130 | int len, off, error = 0;
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131 | struct ethhdr *eh = NULL;
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132 | uint8_t eth_dst[ETH_ALEN];
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133 | int rc = 1;
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134 |
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135 | STAM_PROFILE_START(&pData->StatIP_output, a);
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136 |
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137 | #ifdef LOG_ENABLED
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138 | LogFlowFunc(("ip_output: so = %R[natsock], m0 = %p\n", so, m0));
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139 | #else
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140 | NOREF(so);
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141 | #endif
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142 |
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143 | M_ASSERTPKTHDR(m);
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144 | Assert(m->m_pkthdr.header);
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145 |
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146 | #if 0 /* We do no options */
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147 | if (opt)
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148 | {
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149 | m = ip_insertoptions(m, opt, &len);
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150 | hlen = len;
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151 | }
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152 | #endif
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153 | ip = mtod(m, struct ip *);
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154 | LogFunc(("ip(src:%RTnaipv4, dst:%RTnaipv4)\n", ip->ip_src, ip->ip_dst));
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155 | /*
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156 | * Fill in IP header.
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157 | */
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158 | ip->ip_v = IPVERSION;
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159 | ip->ip_off &= IP_DF;
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160 | ip->ip_id = RT_H2N_U16(ip_currid);
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161 | ip->ip_hl = hlen >> 2;
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162 | ip_currid++;
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163 | ipstat.ips_localout++;
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164 |
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165 | /* Current TCP/IP stack hasn't routing information at
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166 | * all so we need to calculate destination ethernet address
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167 | */
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168 | rc = rt_lookup_in_cache(pData, ip->ip_dst.s_addr, eth_dst);
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169 | if (RT_FAILURE(rc))
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170 | goto exit_drop_package;
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171 |
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172 | eh = (struct ethhdr *)(m->m_data - ETH_HLEN);
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173 | /*
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174 | * If small enough for interface, can just send directly.
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175 | */
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176 | if ((u_int16_t)ip->ip_len <= if_mtu)
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177 | {
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178 | ip->ip_len = RT_H2N_U16((u_int16_t)ip->ip_len);
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179 | ip->ip_off = RT_H2N_U16((u_int16_t)ip->ip_off);
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180 | ip->ip_sum = 0;
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181 | ip->ip_sum = cksum(m, hlen);
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182 |
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183 | if (!(m->m_flags & M_SKIP_FIREWALL)){
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184 | STAM_PROFILE_START(&pData->StatALIAS_output, b);
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185 | rc = LibAliasOut(pData->proxy_alias, mtod(m, char *), m_length(m, NULL));
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186 | if (rc == PKT_ALIAS_IGNORED)
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187 | {
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188 | Log(("NAT: packet was droppped\n"));
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189 | goto exit_drop_package;
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190 | }
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191 | STAM_PROFILE_STOP(&pData->StatALIAS_output, b);
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192 | }
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193 | else
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194 | m->m_flags &= ~M_SKIP_FIREWALL;
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195 |
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196 | memcpy(eh->h_source, eth_dst, ETH_ALEN);
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197 |
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198 | LogFlowFunc(("ip(ip_src:%RTnaipv4, ip_dst:%RTnaipv4)\n",
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199 | ip->ip_src, ip->ip_dst));
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200 | if_encap(pData, ETH_P_IP, m, urg? ETH_ENCAP_URG : 0);
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201 | goto done;
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202 | }
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203 |
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204 | /*
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205 | * Too large for interface; fragment if possible.
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206 | * Must be able to put at least 8 bytes per fragment.
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207 | */
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208 | if (ip->ip_off & IP_DF)
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209 | {
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210 | error = -1;
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211 | ipstat.ips_cantfrag++;
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212 | goto exit_drop_package;
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213 | }
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214 |
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215 | len = (if_mtu - hlen) &~ 7; /* ip databytes per packet */
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216 | if (len < 8)
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217 | {
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218 | error = -1;
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219 | goto exit_drop_package;
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220 | }
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221 |
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222 | {
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223 | int mhlen, firstlen = len;
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224 | struct mbuf **mnext = &m->m_nextpkt;
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225 | char *buf; /* intermediate buffer we'll use for a copy of the original packet */
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226 | /*
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227 | * Loop through length of segment after first fragment,
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228 | * make new header and copy data of each part and link onto chain.
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229 | */
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230 | m0 = m;
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231 | mhlen = ip->ip_hl << 2;
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232 | Log(("NAT:ip:frag: mhlen = %d\n", mhlen));
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233 | for (off = hlen + len; off < (u_int16_t)ip->ip_len; off += len)
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234 | {
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235 | register struct ip *mhip;
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236 | m = m_getjcl(pData, M_NOWAIT, MT_HEADER , M_PKTHDR, slirp_size(pData));
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237 | if (m == 0)
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238 | {
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239 | error = -1;
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240 | ipstat.ips_odropped++;
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241 | goto exit_drop_package;
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242 | }
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243 | m->m_data += if_maxlinkhdr;
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244 | mhip = mtod(m, struct ip *);
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245 | *mhip = *ip;
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246 | m->m_pkthdr.header = mtod(m, void *);
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247 | /* we've calculated eth_dst for first packet */
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248 | #if 0 /* No options */
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249 | if (hlen > sizeof (struct ip))
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250 | {
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251 | mhlen = ip_optcopy(ip, mhip) + sizeof (struct ip);
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252 | mhip->ip_hl = mhlen >> 2;
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253 | }
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254 | #endif
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255 | m->m_len = mhlen;
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256 | mhip->ip_off = ((off - mhlen) >> 3) + (ip->ip_off & ~IP_MF);
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257 | if (ip->ip_off & IP_MF)
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258 | mhip->ip_off |= IP_MF;
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259 | if (off + len >= (u_int16_t)ip->ip_len)
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260 | len = (u_int16_t)ip->ip_len - off;
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261 | else
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262 | mhip->ip_off |= IP_MF;
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263 | mhip->ip_len = RT_H2N_U16((u_int16_t)(len + mhlen));
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264 |
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265 | buf = RTMemAlloc(len);
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266 | Log(("NAT:ip:frag: alloc = %d\n", len));
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267 | m_copydata(m0, off, len, buf); /* copy to buffer */
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268 | Log(("NAT:ip:frag: m_copydata(m0 = %p,off = %d, len = %d,)\n", m0, off, len));
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269 |
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270 | m->m_data += mhlen;
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271 | m->m_len -= mhlen;
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272 | m_copyback(pData, m, 0, len, buf); /* copy from buffer */
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273 | Log(("NAT:ip:frag: m_copyback(m = %p,, len = %d,)\n", m, len));
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274 | m->m_data -= mhlen;
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275 | m->m_len += mhlen;
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276 | RTMemFree(buf);
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277 | Assert((m->m_len == (mhlen + len)));
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278 |
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279 | mhip->ip_off = RT_H2N_U16((u_int16_t)(mhip->ip_off));
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280 | mhip->ip_sum = 0;
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281 | mhip->ip_sum = cksum(m, mhlen);
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282 | *mnext = m;
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283 | mnext = &m->m_nextpkt;
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284 | ipstat.ips_ofragments++;
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285 | }
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286 | /*
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287 | * Update first fragment by trimming what's been copied out
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288 | * and updating header, then send each fragment (in order).
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289 | *
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290 | * note: m_adj do all required releases for chained mbufs.
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291 | */
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292 | m = m0;
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293 | m_adj(m, mhlen + firstlen - (u_int16_t)ip->ip_len);
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294 | Log(("NAT:ip:frag: m_adj(m(m_len:%d) = %p, len = %d)\n", m->m_len, m, mhlen + firstlen - (u_int16_t)ip->ip_len));
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295 | ip->ip_len = RT_H2N_U16((u_int16_t)mhlen + firstlen);
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296 | ip->ip_off = RT_H2N_U16((u_int16_t)(ip->ip_off | IP_MF));
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297 | ip->ip_sum = 0;
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298 | ip->ip_sum = cksum(m, mhlen);
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299 |
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300 | if (!(m->m_flags & M_SKIP_FIREWALL)){
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301 | /** @todo We can't alias all fragments because the way libalias processing
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302 | * the fragments brake the sequence. libalias put alias_address to the source
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303 | * address of IP header of fragment, while IP header of the first packet is
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304 | * is unmodified. That confuses guest's TCP/IP stack and guest drop the sequence.
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305 | * Here we're letting libalias to process the first packet and send the rest as is,
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306 | * it's exactly the way in of packet are processing in proxyonly way.
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307 | * Here we need investigate what should be done to avoid such behavior and find right
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308 | * solution.
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309 | */
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310 | int rcLa;
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311 |
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312 | rcLa = LibAliasOut(pData->proxy_alias, mtod(m, char *), m->m_len);
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313 | if (rcLa == PKT_ALIAS_IGNORED)
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314 | {
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315 | Log(("NAT: packet was droppped\n"));
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316 | goto exit_drop_package;
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317 | }
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318 | Log2(("NAT: LibAlias return %d\n", rcLa));
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319 | }
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320 | else
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321 | m->m_flags &= ~M_SKIP_FIREWALL;
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322 | for (m = m0; m; m = m0)
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323 | {
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324 | m0 = m->m_nextpkt;
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325 | m->m_nextpkt = 0;
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326 | if (error == 0)
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327 | {
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328 | m->m_data -= ETH_HLEN;
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329 | eh = mtod(m, struct ethhdr *);
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330 | m->m_data += ETH_HLEN;
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331 | memcpy(eh->h_source, eth_dst, ETH_ALEN);
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332 |
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333 | Log(("NAT:ip:frag: if_encap(,,m(m_len = %d) = %p,0)\n", m->m_len, m));
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334 | if_encap(pData, ETH_P_IP, m, 0);
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335 | }
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336 | else
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337 | m_freem(pData, m);
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338 | }
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339 |
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340 | if (error == 0)
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341 | ipstat.ips_fragmented++;
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342 | }
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343 |
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344 | done:
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345 | STAM_PROFILE_STOP(&pData->StatIP_output, a);
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346 | LogFlowFunc(("LEAVE: %d\n", error));
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347 | return error;
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348 |
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349 | exit_drop_package:
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350 | m_freem(pData, m0);
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351 | STAM_PROFILE_STOP(&pData->StatIP_output, a);
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352 | LogFlowFunc(("LEAVE: %d\n", error));
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353 | return error;
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354 | }
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