1 | /**
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2 | * @file
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3 | * DNS-SD APIs used by LWIP_HOOK_NETCONN_EXTERNAL_RESOLVE
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4 | *
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5 | * This implementation assumes the DNS-SD API implementation (most likely provided by
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6 | * mDNSResponder) is implemented in the same process space as LwIP and can directly
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7 | * invoke the callback for DNSServiceGetAddrInfo. This is the typical deployment in
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8 | * an embedded environment where as a traditional OS requires pumping the callback results
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9 | * through an IPC mechanism (see DNSServiceRefSockFD/DNSServiceProcessResult)
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10 | *
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11 | * @defgroup dnssd DNS-SD
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12 | * @ingroup dns
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13 | */
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14 |
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15 | /*
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16 | * Copyright (c) 2017 Joel Cunningham, Garmin International, Inc. <joel.cunningham@garmin.com>
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17 | * All rights reserved.
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18 | *
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19 | * Redistribution and use in source and binary forms, with or without modification,
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20 | * are permitted provided that the following conditions are met:
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21 | *
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22 | * 1. Redistributions of source code must retain the above copyright notice,
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23 | * this list of conditions and the following disclaimer.
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24 | * 2. Redistributions in binary form must reproduce the above copyright notice,
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25 | * this list of conditions and the following disclaimer in the documentation
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26 | * and/or other materials provided with the distribution.
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27 | * 3. The name of the author may not be used to endorse or promote products
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28 | * derived from this software without specific prior written permission.
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29 | *
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30 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
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31 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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32 | * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
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33 | * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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34 | * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
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35 | * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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36 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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37 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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38 | * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
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39 | * OF SUCH DAMAGE.
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40 | *
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41 | * This file is part of the lwIP TCP/IP stack.
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42 | *
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43 | * Author: Joel Cunningham <joel.cunningham@me.com>
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44 | *
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45 | */
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46 | #include "lwip/opt.h"
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47 |
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48 | #include "lwip/err.h"
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49 | #include "lwip/inet.h"
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50 | #include "lwip/sockets.h"
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51 | #include "lwip/sys.h"
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52 |
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53 | #include "dnssd.h"
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54 |
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55 | /* External headers */
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56 | #include <string.h>
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57 | #include <dns_sd.h>
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58 |
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59 | /* This timeout should allow for multiple queries.
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60 | mDNSResponder has the following query timeline:
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61 | Query 1: time = 0s
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62 | Query 2: time = 1s
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63 | Query 3: time = 4s
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64 | */
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65 | #define GETADDR_TIMEOUT_MS 5000
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66 | #define LOCAL_DOMAIN ".local"
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67 |
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68 | /* Only consume .local hosts */
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69 | #ifndef CONSUME_LOCAL_ONLY
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70 | #define CONSUME_LOCAL_ONLY 1
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71 | #endif
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72 |
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73 | struct addr_clbk_msg {
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74 | sys_sem_t sem;
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75 | struct sockaddr_storage addr;
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76 | err_t err;
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77 | };
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78 |
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79 | static void addr_info_callback(DNSServiceRef ref, DNSServiceFlags flags, u32_t interface_index,
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80 | DNSServiceErrorType error_code, char const* hostname,
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81 | const struct sockaddr* address, u32_t ttl, void* context);
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82 |
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83 | int
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84 | lwip_dnssd_gethostbyname(const char *name, ip_addr_t *addr, u8_t addrtype, err_t *err)
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85 | {
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86 | DNSServiceErrorType result;
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87 | DNSServiceRef ref;
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88 | struct addr_clbk_msg msg;
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89 | char *p;
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90 |
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91 | /* @todo: use with IPv6 */
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92 | LWIP_UNUSED_ARG(addrtype);
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93 |
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94 | #if CONSUME_LOCAL_ONLY
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95 | /* check if this is a .local host. If it is, then we consume the query */
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96 | p = strstr(name, LOCAL_DOMAIN);
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97 | if (p == NULL) {
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98 | return 0; /* not consumed */
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99 | }
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100 | p += (sizeof(LOCAL_DOMAIN) - 1);
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101 | /* check to make sure .local isn't a substring (only allow .local\0 or .local.\0) */
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102 | if ((*p != '.' && *p != '\0') ||
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103 | (*p == '.' && *(p + 1) != '\0')) {
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104 | return 0; /* not consumed */
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105 | }
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106 | #endif /* CONSUME_LOCAL_ONLY */
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107 |
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108 | msg.err = sys_sem_new(&msg.sem, 0);
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109 | if (msg.err != ERR_OK) {
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110 | goto query_done;
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111 | }
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112 |
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113 | msg.err = ERR_TIMEOUT;
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114 | result = DNSServiceGetAddrInfo(&ref, 0, 0, kDNSServiceProtocol_IPv4, name, addr_info_callback, &msg);
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115 | if (result == kDNSServiceErr_NoError) {
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116 | sys_arch_sem_wait(&msg.sem, GETADDR_TIMEOUT_MS);
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117 | DNSServiceRefDeallocate(ref);
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118 |
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119 | /* We got a response */
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120 | if (msg.err == ERR_OK) {
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121 | struct sockaddr_in* addr_in = (struct sockaddr_in *)&msg.addr;
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122 | if (addr_in->sin_family == AF_INET) {
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123 | inet_addr_to_ip4addr(ip_2_ip4(addr), &addr_in->sin_addr);
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124 | } else {
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125 | /* @todo add IPv6 support */
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126 | msg.err = ERR_VAL;
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127 | }
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128 | }
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129 | }
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130 | sys_sem_free(&msg.sem);
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131 |
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132 | /* Query has been consumed and is finished */
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133 | query_done:
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134 | *err = msg.err;
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135 | return 1;
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136 | }
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137 |
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138 | static void
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139 | addr_info_callback(DNSServiceRef ref, DNSServiceFlags flags, u32_t interface_index,
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140 | DNSServiceErrorType error_code, char const* hostname,
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141 | const struct sockaddr* address, u32_t ttl, void* context)
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142 | {
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143 | struct addr_clbk_msg* msg = (struct addr_clbk_msg*)context;
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144 | struct sockaddr_in* addr_in = (struct sockaddr_in *)address;
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145 |
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146 | LWIP_UNUSED_ARG(ref);
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147 | LWIP_UNUSED_ARG(flags);
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148 | LWIP_UNUSED_ARG(interface_index);
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149 | LWIP_UNUSED_ARG(hostname);
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150 | LWIP_UNUSED_ARG(ttl);
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151 | LWIP_UNUSED_ARG(context);
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152 |
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153 | if ((error_code == kDNSServiceErr_NoError) &&
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154 | (addr_in->sin_family == AF_INET)) {
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155 | MEMCPY(&msg->addr, addr_in, sizeof(*addr_in));
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156 | msg->err = ERR_OK;
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157 | }
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158 | else {
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159 | /* @todo add IPv6 support */
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160 | msg->err = ERR_VAL;
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161 | }
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162 |
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163 | sys_sem_signal(&msg->sem);
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164 | } /* addr_info_callback() */
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