1 | /* $Id: proxy_dhcp6ds.c 63567 2016-08-16 14:06:54Z vboxsync $ */
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2 | /** @file
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3 | * NAT Network - Simple stateless DHCPv6 (RFC 3736) server.
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4 | */
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5 |
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6 | /*
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7 | * Copyright (C) 2013-2016 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.virtualbox.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 | #define LOG_GROUP LOG_GROUP_NAT_SERVICE
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19 |
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20 | #include "winutils.h"
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21 | #include "dhcp6.h"
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22 | #include "proxy.h"
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23 |
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24 | #include <string.h>
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25 |
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26 | #include "lwip/opt.h"
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27 | #include "lwip/mld6.h"
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28 | #include "lwip/udp.h"
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29 |
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30 |
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31 | static void dhcp6ds_recv(void *, struct udp_pcb *, struct pbuf *, ip6_addr_t *, u16_t);
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32 |
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33 |
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34 | /* ff02::1:2 - "All_DHCP_Relay_Agents_and_Servers" link-scoped multicast */
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35 | static /* const */ ip6_addr_t all_dhcp_relays_and_servers = {
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36 | { PP_HTONL(0xff020000UL), 0, 0, PP_HTONL(0x00010002UL) }
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37 | };
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38 |
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39 | /* ff05::1:3 - "All_DHCP_Servers" site-scoped multicast */
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40 | static /* const */ ip6_addr_t all_dhcp_servers = {
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41 | { PP_HTONL(0xff050000UL), 0, 0, PP_HTONL(0x00010003UL) }
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42 | };
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43 |
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44 |
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45 | static struct udp_pcb *dhcp6ds_pcb;
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46 |
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47 | /* prebuilt Server ID option */
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48 | #define DUID_LL_LEN (/* duid type */ 2 + /* hw type */ 2 + /* ether addr */ 6)
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49 | static u8_t dhcp6ds_serverid[/* opt */ 2 + /* optlen */ 2 + DUID_LL_LEN];
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50 |
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51 | /* prebuilt DNS Servers option */
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52 | static u8_t dhcp6ds_dns[/* opt */ 2 + /* optlen */ 2 + /* IPv6 addr */ 16];
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53 |
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54 |
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55 | /**
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56 | * Initialize DHCP6 server.
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57 | *
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58 | * Join DHCP6 multicast groups.
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59 | * Create and bind server pcb.
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60 | * Prebuild fixed parts of reply.
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61 | */
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62 | err_t
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63 | dhcp6ds_init(struct netif *proxy_netif)
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64 | {
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65 | ip6_addr_t *pxaddr, *pxaddr_nonlocal;
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66 | int i;
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67 | err_t error;
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68 |
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69 | LWIP_ASSERT1(proxy_netif != NULL);
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70 | LWIP_ASSERT1(proxy_netif->hwaddr_len == 6); /* ethernet */
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71 |
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72 | pxaddr = netif_ip6_addr(proxy_netif, 0); /* link local */
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73 |
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74 | /*
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75 | * XXX: TODO: This is a leftover from testing with IPv6 mapped
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76 | * loopback with a special IPv6->IPv4 mapping hack in pxudp.c
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77 | */
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78 | /* advertise ourself as DNS resolver - will be proxied to host */
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79 | pxaddr_nonlocal = NULL;
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80 | for (i = 1; i < LWIP_IPV6_NUM_ADDRESSES; ++i) {
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81 | if (ip6_addr_ispreferred(netif_ip6_addr_state(proxy_netif, i))
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82 | && !ip6_addr_islinklocal(netif_ip6_addr(proxy_netif, i)))
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83 | {
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84 | pxaddr_nonlocal = netif_ip6_addr(proxy_netif, i);
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85 | break;
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86 | }
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87 | }
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88 | LWIP_ASSERT1(pxaddr_nonlocal != NULL); /* must be configured on the netif */
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89 |
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90 |
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91 | error = mld6_joingroup(pxaddr, &all_dhcp_relays_and_servers);
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92 | if (error != ERR_OK) {
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93 | DPRINTF0(("%s: failed to join All_DHCP_Relay_Agents_and_Servers: %s\n",
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94 | __func__, proxy_lwip_strerr(error)));
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95 | goto err;
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96 | }
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97 |
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98 | error = mld6_joingroup(pxaddr, &all_dhcp_servers);
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99 | if (error != ERR_OK) {
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100 | DPRINTF0(("%s: failed to join All_DHCP_Servers: %s\n",
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101 | __func__, proxy_lwip_strerr(error)));
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102 | goto err1;
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103 | }
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104 |
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105 |
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106 | dhcp6ds_pcb = udp_new_ip6();
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107 | if (dhcp6ds_pcb == NULL) {
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108 | DPRINTF0(("%s: failed to allocate PCB\n", __func__));
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109 | error = ERR_MEM;
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110 | goto err2;
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111 | }
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112 |
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113 | udp_recv_ip6(dhcp6ds_pcb, dhcp6ds_recv, NULL);
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114 |
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115 | error = udp_bind_ip6(dhcp6ds_pcb, pxaddr, DHCP6_SERVER_PORT);
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116 | if (error != ERR_OK) {
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117 | DPRINTF0(("%s: failed to bind PCB\n", __func__));
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118 | goto err3;
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119 | }
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120 |
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121 |
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122 | #define OPT_SET(buf, off, c) do { \
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123 | u16_t _s = PP_HTONS(c); \
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124 | memcpy(&(buf)[off], &_s, sizeof(u16_t)); \
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125 | } while (0)
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126 |
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127 | #define SERVERID_SET(off, c) OPT_SET(dhcp6ds_serverid, (off), (c))
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128 | #define DNSSRV_SET(off, c) OPT_SET(dhcp6ds_dns, (off), (c))
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129 |
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130 | SERVERID_SET(0, DHCP6_OPTION_SERVERID);
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131 | SERVERID_SET(2, DUID_LL_LEN);
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132 | SERVERID_SET(4, DHCP6_DUID_LL);
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133 | SERVERID_SET(6, ARES_HRD_ETHERNET);
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134 | memcpy(&dhcp6ds_serverid[8], proxy_netif->hwaddr, 6);
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135 |
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136 | DNSSRV_SET(0, DHCP6_OPTION_DNS_SERVERS);
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137 | DNSSRV_SET(2, 16); /* one IPv6 address */
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138 | /*
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139 | * XXX: TODO: This is a leftover from testing with IPv6 mapped
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140 | * loopback with a special IPv6->IPv4 mapping hack in pxudp.c
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141 | */
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142 | memcpy(&dhcp6ds_dns[4], pxaddr_nonlocal, sizeof(ip6_addr_t));
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143 |
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144 | #undef SERVERID_SET
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145 | #undef DNSSRV_SET
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146 |
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147 | return ERR_OK;
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148 |
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149 |
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150 | err3:
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151 | udp_remove(dhcp6ds_pcb);
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152 | dhcp6ds_pcb = NULL;
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153 | err2:
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154 | mld6_leavegroup(pxaddr, &all_dhcp_servers);
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155 | err1:
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156 | mld6_leavegroup(pxaddr, &all_dhcp_relays_and_servers);
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157 | err:
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158 | return error;
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159 | }
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160 |
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161 |
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162 | static u8_t dhcp6ds_reply_buf[1024];
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163 |
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164 | static void
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165 | dhcp6ds_recv(void *arg, struct udp_pcb *pcb, struct pbuf *p,
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166 | ip6_addr_t *addr, u16_t port)
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167 | {
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168 | u8_t msg_header[4];
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169 | unsigned int msg_type, msg_tid;
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170 | int copied;
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171 | size_t roff;
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172 | struct pbuf *q;
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173 | err_t error;
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174 |
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175 | LWIP_UNUSED_ARG(arg);
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176 | LWIP_ASSERT1(p != NULL);
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177 |
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178 | copied = pbuf_copy_partial(p, msg_header, sizeof(msg_header), 0);
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179 | if (copied != sizeof(msg_header)) {
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180 | DPRINTF(("%s: message header truncated\n", __func__));
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181 | pbuf_free(p);
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182 | return;
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183 | }
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184 | pbuf_header(p, -(s16_t)sizeof(msg_header));
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185 |
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186 | msg_type = msg_header[0];
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187 | msg_tid = (msg_header[1] << 16) | (msg_header[2] << 8) | msg_header[3];
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188 | DPRINTF(("%s: type %u, tid 0x%6x\n", __func__, msg_type, msg_tid));
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189 | if (msg_type != DHCP6_INFORMATION_REQUEST) { /** @todo ? RELAY_FORW */
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190 | pbuf_free(p);
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191 | return;
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192 | }
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193 |
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194 | roff = 0;
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195 |
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196 | msg_header[0] = DHCP6_REPLY;
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197 | memcpy(dhcp6ds_reply_buf + roff, msg_header, sizeof(msg_header));
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198 | roff += sizeof(msg_header);
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199 |
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200 |
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201 | /* loop over options */
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202 | while (p->tot_len > 0) {
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203 | u16_t opt, optlen;
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204 |
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205 | /* fetch option code */
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206 | copied = pbuf_copy_partial(p, &opt, sizeof(opt), 0);
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207 | if (copied != sizeof(opt)) {
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208 | DPRINTF(("%s: option header truncated\n", __func__));
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209 | pbuf_free(p);
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210 | return;
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211 | }
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212 | pbuf_header(p, -(s16_t)sizeof(opt));
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213 | opt = ntohs(opt);
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214 |
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215 | /* fetch option length */
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216 | copied = pbuf_copy_partial(p, &optlen, sizeof(optlen), 0);
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217 | if (copied != sizeof(optlen)) {
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218 | DPRINTF(("%s: option %u length truncated\n", __func__, opt));
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219 | pbuf_free(p);
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220 | return;
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221 | }
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222 | pbuf_header(p, -(s16_t)sizeof(optlen));
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223 | optlen = ntohs(optlen);
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224 |
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225 | /* enough data? */
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226 | if (optlen > p->tot_len) {
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227 | DPRINTF(("%s: option %u truncated: expect %u, got %u\n",
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228 | __func__, opt, optlen, p->tot_len));
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229 | pbuf_free(p);
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230 | return;
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231 | }
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232 |
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233 | DPRINTF2(("%s: option %u length %u\n", __func__, opt, optlen));
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234 |
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235 | if (opt == DHCP6_OPTION_CLIENTID) {
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236 | u16_t s;
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237 |
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238 | /* "A DUID can be no more than 128 octets long (not
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239 | including the type code)." */
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240 | if (optlen > 130) {
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241 | DPRINTF(("%s: client DUID too long: %u\n", __func__, optlen));
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242 | pbuf_free(p);
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243 | return;
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244 | }
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245 |
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246 | s = PP_HTONS(DHCP6_OPTION_CLIENTID);
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247 | memcpy(dhcp6ds_reply_buf + roff, &s, sizeof(s));
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248 | roff += sizeof(s);
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249 |
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250 | s = ntohs(optlen);
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251 | memcpy(dhcp6ds_reply_buf + roff, &s, sizeof(s));
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252 | roff += sizeof(s);
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253 |
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254 | pbuf_copy_partial(p, dhcp6ds_reply_buf + roff, optlen, 0);
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255 | roff += optlen;
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256 | }
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257 | else if (opt == DHCP6_OPTION_ORO) {
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258 | u16_t *opts;
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259 | int i, nopts;
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260 |
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261 | if (optlen % 2 != 0) {
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262 | DPRINTF2(("%s: Option Request of odd length\n", __func__));
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263 | goto bad_oro;
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264 | }
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265 | nopts = optlen / 2;
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266 |
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267 | opts = (u16_t *)malloc(optlen);
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268 | if (opts == NULL) {
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269 | DPRINTF2(("%s: failed to allocate space for Option Request\n",
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270 | __func__));
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271 | goto bad_oro;
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272 | }
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273 |
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274 | pbuf_copy_partial(p, opts, optlen, 0);
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275 | for (i = 0; i < nopts; ++i) {
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276 | opt = ntohs(opts[i]);
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277 | DPRINTF2(("> request option %u\n", opt));
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278 | };
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279 | free(opts);
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280 |
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281 | bad_oro: /* empty */;
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282 | }
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283 |
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284 | pbuf_header(p, -optlen); /* go to next option */
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285 | }
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286 | pbuf_free(p); /* done */
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287 |
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288 |
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289 | memcpy(dhcp6ds_reply_buf + roff, dhcp6ds_serverid, sizeof(dhcp6ds_serverid));
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290 | roff += sizeof(dhcp6ds_serverid);
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291 |
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292 | memcpy(dhcp6ds_reply_buf + roff, dhcp6ds_dns, sizeof(dhcp6ds_dns));
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293 | roff += sizeof(dhcp6ds_dns);
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294 |
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295 | Assert(roff == (u16_t)roff);
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296 | q = pbuf_alloc(PBUF_RAW, (u16_t)roff, PBUF_RAM);
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297 | if (q == NULL) {
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298 | DPRINTF(("%s: pbuf_alloc(%d) failed\n", __func__, (int)roff));
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299 | return;
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300 | }
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301 |
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302 | error = pbuf_take(q, dhcp6ds_reply_buf, (u16_t)roff);
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303 | if (error != ERR_OK) {
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304 | DPRINTF(("%s: pbuf_take(%d) failed: %s\n",
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305 | __func__, (int)roff, proxy_lwip_strerr(error)));
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306 | pbuf_free(q);
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307 | return;
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308 | }
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309 |
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310 | error = udp_sendto_ip6(pcb, q, addr, port);
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311 | if (error != ERR_OK) {
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312 | DPRINTF(("%s: udp_sendto failed: %s\n",
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313 | __func__, proxy_lwip_strerr(error)));
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314 | }
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315 |
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316 | pbuf_free(q);
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317 | }
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