1 | /**
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2 | * @file
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3 | * API functions for name resolving
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4 | *
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5 | * @defgroup netdbapi NETDB API
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6 | * @ingroup socket
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7 | */
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8 |
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9 | /*
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10 | * Redistribution and use in source and binary forms, with or without modification,
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11 | * are permitted provided that the following conditions are met:
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12 | *
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13 | * 1. Redistributions of source code must retain the above copyright notice,
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14 | * this list of conditions and the following disclaimer.
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15 | * 2. Redistributions in binary form must reproduce the above copyright notice,
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16 | * this list of conditions and the following disclaimer in the documentation
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17 | * and/or other materials provided with the distribution.
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18 | * 3. The name of the author may not be used to endorse or promote products
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19 | * derived from this software without specific prior written permission.
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20 | *
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21 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
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22 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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23 | * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
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24 | * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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25 | * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
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26 | * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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27 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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28 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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29 | * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
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30 | * OF SUCH DAMAGE.
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31 | *
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32 | * This file is part of the lwIP TCP/IP stack.
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33 | *
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34 | * Author: Simon Goldschmidt
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35 | *
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36 | */
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37 |
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38 | #include "lwip/netdb.h"
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39 |
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40 | #if LWIP_DNS && LWIP_SOCKET
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41 |
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42 | #include "lwip/err.h"
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43 | #include "lwip/mem.h"
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44 | #include "lwip/memp.h"
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45 | #include "lwip/ip_addr.h"
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46 | #include "lwip/api.h"
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47 | #include "lwip/dns.h"
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48 |
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49 | #include <string.h> /* memset */
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50 | #include <stdlib.h> /* atoi */
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51 |
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52 | /** helper struct for gethostbyname_r to access the char* buffer */
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53 | struct gethostbyname_r_helper {
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54 | ip_addr_t *addr_list[2];
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55 | ip_addr_t addr;
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56 | char *aliases;
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57 | };
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58 |
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59 | /** h_errno is exported in netdb.h for access by applications. */
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60 | #if LWIP_DNS_API_DECLARE_H_ERRNO
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61 | int h_errno;
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62 | #endif /* LWIP_DNS_API_DECLARE_H_ERRNO */
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63 |
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64 | /** define "hostent" variables storage: 0 if we use a static (but unprotected)
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65 | * set of variables for lwip_gethostbyname, 1 if we use a local storage */
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66 | #ifndef LWIP_DNS_API_HOSTENT_STORAGE
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67 | #define LWIP_DNS_API_HOSTENT_STORAGE 0
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68 | #endif
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69 |
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70 | /** define "hostent" variables storage */
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71 | #if LWIP_DNS_API_HOSTENT_STORAGE
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72 | #define HOSTENT_STORAGE
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73 | #else
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74 | #define HOSTENT_STORAGE static
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75 | #endif /* LWIP_DNS_API_STATIC_HOSTENT */
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76 |
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77 | /**
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78 | * Returns an entry containing addresses of address family AF_INET
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79 | * for the host with name name.
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80 | * Due to dns_gethostbyname limitations, only one address is returned.
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81 | *
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82 | * @param name the hostname to resolve
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83 | * @return an entry containing addresses of address family AF_INET
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84 | * for the host with name name
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85 | */
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86 | struct hostent *
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87 | lwip_gethostbyname(const char *name)
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88 | {
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89 | err_t err;
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90 | ip_addr_t addr;
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91 |
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92 | /* buffer variables for lwip_gethostbyname() */
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93 | HOSTENT_STORAGE struct hostent s_hostent;
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94 | HOSTENT_STORAGE char *s_aliases;
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95 | HOSTENT_STORAGE ip_addr_t s_hostent_addr;
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96 | HOSTENT_STORAGE ip_addr_t *s_phostent_addr[2];
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97 | HOSTENT_STORAGE char s_hostname[DNS_MAX_NAME_LENGTH + 1];
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98 |
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99 | /* query host IP address */
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100 | err = netconn_gethostbyname(name, &addr);
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101 | if (err != ERR_OK) {
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102 | LWIP_DEBUGF(DNS_DEBUG, ("lwip_gethostbyname(%s) failed, err=%d\n", name, err));
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103 | h_errno = HOST_NOT_FOUND;
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104 | return NULL;
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105 | }
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106 |
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107 | /* fill hostent */
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108 | s_hostent_addr = addr;
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109 | s_phostent_addr[0] = &s_hostent_addr;
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110 | s_phostent_addr[1] = NULL;
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111 | strncpy(s_hostname, name, DNS_MAX_NAME_LENGTH);
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112 | s_hostname[DNS_MAX_NAME_LENGTH] = 0;
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113 | s_hostent.h_name = s_hostname;
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114 | s_aliases = NULL;
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115 | s_hostent.h_aliases = &s_aliases;
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116 | s_hostent.h_addrtype = AF_INET;
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117 | s_hostent.h_length = sizeof(ip_addr_t);
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118 | s_hostent.h_addr_list = (char **)&s_phostent_addr;
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119 |
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120 | #if DNS_DEBUG
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121 | /* dump hostent */
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122 | LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_name == %s\n", s_hostent.h_name));
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123 | LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_aliases == %p\n", (void *)s_hostent.h_aliases));
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124 | /* h_aliases are always empty */
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125 | LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_addrtype == %d\n", s_hostent.h_addrtype));
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126 | LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_length == %d\n", s_hostent.h_length));
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127 | LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_addr_list == %p\n", (void *)s_hostent.h_addr_list));
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128 | if (s_hostent.h_addr_list != NULL) {
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129 | u8_t idx;
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130 | for (idx = 0; s_hostent.h_addr_list[idx]; idx++) {
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131 | LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_addr_list[%i] == %p\n", idx, s_hostent.h_addr_list[idx]));
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132 | LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_addr_list[%i]-> == %s\n", idx, ipaddr_ntoa((ip_addr_t *)s_hostent.h_addr_list[idx])));
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133 | }
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134 | }
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135 | #endif /* DNS_DEBUG */
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136 |
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137 | #if LWIP_DNS_API_HOSTENT_STORAGE
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138 | /* this function should return the "per-thread" hostent after copy from s_hostent */
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139 | return sys_thread_hostent(&s_hostent);
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140 | #else
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141 | return &s_hostent;
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142 | #endif /* LWIP_DNS_API_HOSTENT_STORAGE */
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143 | }
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144 |
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145 | /**
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146 | * Thread-safe variant of lwip_gethostbyname: instead of using a static
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147 | * buffer, this function takes buffer and errno pointers as arguments
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148 | * and uses these for the result.
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149 | *
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150 | * @param name the hostname to resolve
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151 | * @param ret pre-allocated struct where to store the result
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152 | * @param buf pre-allocated buffer where to store additional data
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153 | * @param buflen the size of buf
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154 | * @param result pointer to a hostent pointer that is set to ret on success
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155 | * and set to zero on error
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156 | * @param h_errnop pointer to an int where to store errors (instead of modifying
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157 | * the global h_errno)
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158 | * @return 0 on success, non-zero on error, additional error information
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159 | * is stored in *h_errnop instead of h_errno to be thread-safe
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160 | */
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161 | int
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162 | lwip_gethostbyname_r(const char *name, struct hostent *ret, char *buf,
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163 | size_t buflen, struct hostent **result, int *h_errnop)
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164 | {
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165 | err_t err;
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166 | struct gethostbyname_r_helper *h;
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167 | char *hostname;
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168 | size_t namelen;
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169 | int lh_errno;
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170 |
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171 | if (h_errnop == NULL) {
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172 | /* ensure h_errnop is never NULL */
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173 | h_errnop = &lh_errno;
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174 | }
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175 |
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176 | if (result == NULL) {
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177 | /* not all arguments given */
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178 | *h_errnop = EINVAL;
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179 | return -1;
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180 | }
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181 | /* first thing to do: set *result to nothing */
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182 | *result = NULL;
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183 | if ((name == NULL) || (ret == NULL) || (buf == NULL)) {
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184 | /* not all arguments given */
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185 | *h_errnop = EINVAL;
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186 | return -1;
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187 | }
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188 |
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189 | namelen = strlen(name);
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190 | if (buflen < (sizeof(struct gethostbyname_r_helper) + LWIP_MEM_ALIGN_BUFFER(namelen + 1))) {
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191 | /* buf can't hold the data needed + a copy of name */
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192 | *h_errnop = ERANGE;
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193 | return -1;
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194 | }
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195 |
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196 | h = (struct gethostbyname_r_helper *)LWIP_MEM_ALIGN(buf);
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197 | hostname = ((char *)h) + sizeof(struct gethostbyname_r_helper);
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198 |
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199 | /* query host IP address */
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200 | err = netconn_gethostbyname(name, &h->addr);
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201 | if (err != ERR_OK) {
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202 | LWIP_DEBUGF(DNS_DEBUG, ("lwip_gethostbyname(%s) failed, err=%d\n", name, err));
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203 | *h_errnop = HOST_NOT_FOUND;
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204 | return -1;
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205 | }
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206 |
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207 | /* copy the hostname into buf */
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208 | MEMCPY(hostname, name, namelen);
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209 | hostname[namelen] = 0;
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210 |
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211 | /* fill hostent */
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212 | h->addr_list[0] = &h->addr;
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213 | h->addr_list[1] = NULL;
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214 | h->aliases = NULL;
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215 | ret->h_name = hostname;
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216 | ret->h_aliases = &h->aliases;
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217 | ret->h_addrtype = AF_INET;
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218 | ret->h_length = sizeof(ip_addr_t);
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219 | ret->h_addr_list = (char **)&h->addr_list;
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220 |
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221 | /* set result != NULL */
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222 | *result = ret;
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223 |
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224 | /* return success */
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225 | return 0;
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226 | }
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227 |
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228 | /**
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229 | * Frees one or more addrinfo structures returned by getaddrinfo(), along with
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230 | * any additional storage associated with those structures. If the ai_next field
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231 | * of the structure is not null, the entire list of structures is freed.
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232 | *
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233 | * @param ai struct addrinfo to free
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234 | */
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235 | void
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236 | lwip_freeaddrinfo(struct addrinfo *ai)
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237 | {
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238 | struct addrinfo *next;
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239 |
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240 | while (ai != NULL) {
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241 | next = ai->ai_next;
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242 | memp_free(MEMP_NETDB, ai);
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243 | ai = next;
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244 | }
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245 | }
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246 |
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247 | /**
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248 | * Translates the name of a service location (for example, a host name) and/or
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249 | * a service name and returns a set of socket addresses and associated
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250 | * information to be used in creating a socket with which to address the
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251 | * specified service.
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252 | * Memory for the result is allocated internally and must be freed by calling
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253 | * lwip_freeaddrinfo()!
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254 | *
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255 | * Due to a limitation in dns_gethostbyname, only the first address of a
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256 | * host is returned.
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257 | * Also, service names are not supported (only port numbers)!
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258 | *
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259 | * @param nodename descriptive name or address string of the host
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260 | * (may be NULL -> local address)
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261 | * @param servname port number as string of NULL
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262 | * @param hints structure containing input values that set socktype and protocol
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263 | * @param res pointer to a pointer where to store the result (set to NULL on failure)
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264 | * @return 0 on success, non-zero on failure
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265 | *
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266 | * @todo: implement AI_V4MAPPED, AI_ADDRCONFIG
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267 | */
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268 | int
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269 | lwip_getaddrinfo(const char *nodename, const char *servname,
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270 | const struct addrinfo *hints, struct addrinfo **res)
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271 | {
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272 | err_t err;
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273 | ip_addr_t addr;
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274 | struct addrinfo *ai;
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275 | struct sockaddr_storage *sa = NULL;
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276 | int port_nr = 0;
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277 | size_t total_size;
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278 | size_t namelen = 0;
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279 | int ai_family;
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280 |
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281 | if (res == NULL) {
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282 | return EAI_FAIL;
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283 | }
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284 | *res = NULL;
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285 | if ((nodename == NULL) && (servname == NULL)) {
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286 | return EAI_NONAME;
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287 | }
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288 |
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289 | if (hints != NULL) {
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290 | ai_family = hints->ai_family;
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291 | if ((ai_family != AF_UNSPEC)
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292 | #if LWIP_IPV4
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293 | && (ai_family != AF_INET)
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294 | #endif /* LWIP_IPV4 */
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295 | #if LWIP_IPV6
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296 | && (ai_family != AF_INET6)
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297 | #endif /* LWIP_IPV6 */
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298 | ) {
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299 | return EAI_FAMILY;
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300 | }
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301 | } else {
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302 | ai_family = AF_UNSPEC;
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303 | }
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304 |
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305 | if (servname != NULL) {
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306 | /* service name specified: convert to port number
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307 | * @todo?: currently, only ASCII integers (port numbers) are supported (AI_NUMERICSERV)! */
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308 | port_nr = atoi(servname);
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309 | if ((port_nr <= 0) || (port_nr > 0xffff)) {
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310 | return EAI_SERVICE;
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311 | }
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312 | }
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313 |
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314 | if (nodename != NULL) {
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315 | /* service location specified, try to resolve */
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316 | if ((hints != NULL) && (hints->ai_flags & AI_NUMERICHOST)) {
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317 | /* no DNS lookup, just parse for an address string */
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318 | if (!ipaddr_aton(nodename, &addr)) {
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319 | return EAI_NONAME;
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320 | }
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321 | #if LWIP_IPV4 && LWIP_IPV6
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322 | if ((IP_IS_V6_VAL(addr) && ai_family == AF_INET) ||
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323 | (IP_IS_V4_VAL(addr) && ai_family == AF_INET6)) {
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324 | return EAI_NONAME;
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325 | }
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326 | #endif /* LWIP_IPV4 && LWIP_IPV6 */
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327 | } else {
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328 | #if LWIP_IPV4 && LWIP_IPV6
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329 | /* AF_UNSPEC: prefer IPv4 */
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330 | u8_t type = NETCONN_DNS_IPV4_IPV6;
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331 | if (ai_family == AF_INET) {
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332 | type = NETCONN_DNS_IPV4;
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333 | } else if (ai_family == AF_INET6) {
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334 | type = NETCONN_DNS_IPV6;
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335 | }
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336 | #endif /* LWIP_IPV4 && LWIP_IPV6 */
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337 | err = netconn_gethostbyname_addrtype(nodename, &addr, type);
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338 | if (err != ERR_OK) {
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339 | return EAI_FAIL;
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340 | }
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341 | }
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342 | } else {
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343 | /* service location specified, use loopback address */
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344 | if ((hints != NULL) && (hints->ai_flags & AI_PASSIVE)) {
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345 | ip_addr_set_any_val(ai_family == AF_INET6, addr);
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346 | } else {
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347 | ip_addr_set_loopback_val(ai_family == AF_INET6, addr);
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348 | }
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349 | }
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350 |
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351 | total_size = sizeof(struct addrinfo) + sizeof(struct sockaddr_storage);
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352 | if (nodename != NULL) {
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353 | namelen = strlen(nodename);
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354 | if (namelen > DNS_MAX_NAME_LENGTH) {
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355 | /* invalid name length */
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356 | return EAI_FAIL;
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357 | }
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358 | LWIP_ASSERT("namelen is too long", total_size + namelen + 1 > total_size);
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359 | total_size += namelen + 1;
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360 | }
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361 | /* If this fails, please report to lwip-devel! :-) */
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362 | LWIP_ASSERT("total_size <= NETDB_ELEM_SIZE: please report this!",
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363 | total_size <= NETDB_ELEM_SIZE);
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364 | ai = (struct addrinfo *)memp_malloc(MEMP_NETDB);
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365 | if (ai == NULL) {
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366 | return EAI_MEMORY;
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367 | }
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368 | memset(ai, 0, total_size);
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369 | /* cast through void* to get rid of alignment warnings */
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370 | sa = (struct sockaddr_storage *)(void *)((u8_t *)ai + sizeof(struct addrinfo));
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371 | if (IP_IS_V6_VAL(addr)) {
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372 | #if LWIP_IPV6
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373 | struct sockaddr_in6 *sa6 = (struct sockaddr_in6 *)sa;
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374 | /* set up sockaddr */
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375 | inet6_addr_from_ip6addr(&sa6->sin6_addr, ip_2_ip6(&addr));
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376 | sa6->sin6_family = AF_INET6;
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377 | sa6->sin6_len = sizeof(struct sockaddr_in6);
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378 | sa6->sin6_port = lwip_htons((u16_t)port_nr);
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379 | sa6->sin6_scope_id = ip6_addr_zone(ip_2_ip6(&addr));
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380 | ai->ai_family = AF_INET6;
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381 | #endif /* LWIP_IPV6 */
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382 | } else {
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383 | #if LWIP_IPV4
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384 | struct sockaddr_in *sa4 = (struct sockaddr_in *)sa;
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385 | /* set up sockaddr */
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386 | inet_addr_from_ip4addr(&sa4->sin_addr, ip_2_ip4(&addr));
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387 | sa4->sin_family = AF_INET;
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388 | sa4->sin_len = sizeof(struct sockaddr_in);
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389 | sa4->sin_port = lwip_htons((u16_t)port_nr);
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390 | ai->ai_family = AF_INET;
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391 | #endif /* LWIP_IPV4 */
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392 | }
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393 |
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394 | /* set up addrinfo */
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395 | if (hints != NULL) {
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396 | /* copy socktype & protocol from hints if specified */
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397 | ai->ai_socktype = hints->ai_socktype;
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398 | ai->ai_protocol = hints->ai_protocol;
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399 | }
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400 | if (nodename != NULL) {
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401 | /* copy nodename to canonname if specified */
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402 | ai->ai_canonname = ((char *)ai + sizeof(struct addrinfo) + sizeof(struct sockaddr_storage));
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403 | MEMCPY(ai->ai_canonname, nodename, namelen);
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404 | ai->ai_canonname[namelen] = 0;
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405 | }
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406 | ai->ai_addrlen = sizeof(struct sockaddr_storage);
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407 | ai->ai_addr = (struct sockaddr *)sa;
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408 |
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409 | *res = ai;
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410 |
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411 | return 0;
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412 | }
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413 |
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414 | #endif /* LWIP_DNS && LWIP_SOCKET */
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