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netdb.c
00001 /** 00002 * @file 00003 * API functions for name resolving 00004 * 00005 */ 00006 00007 /* 00008 * Redistribution and use in source and binary forms, with or without modification, 00009 * are permitted provided that the following conditions are met: 00010 * 00011 * 1. Redistributions of source code must retain the above copyright notice, 00012 * this list of conditions and the following disclaimer. 00013 * 2. Redistributions in binary form must reproduce the above copyright notice, 00014 * this list of conditions and the following disclaimer in the documentation 00015 * and/or other materials provided with the distribution. 00016 * 3. The name of the author may not be used to endorse or promote products 00017 * derived from this software without specific prior written permission. 00018 * 00019 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED 00020 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 00021 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT 00022 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 00023 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT 00024 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 00025 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 00026 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING 00027 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY 00028 * OF SUCH DAMAGE. 00029 * 00030 * This file is part of the lwIP TCP/IP stack. 00031 * 00032 * Author: Simon Goldschmidt 00033 * 00034 */ 00035 00036 #include "lwip/netdb.h" 00037 00038 #if LWIP_DNS && LWIP_SOCKET 00039 00040 #include "lwip/err.h" 00041 #include "lwip/mem.h" 00042 #include "lwip/memp.h" 00043 #include "lwip/ip_addr.h" 00044 #include "lwip/api.h" 00045 #include "lwip/dns.h" 00046 00047 #include <string.h> 00048 #include <stdlib.h> 00049 00050 /** helper struct for gethostbyname_r to access the char* buffer */ 00051 struct gethostbyname_r_helper { 00052 ip_addr_t *addrs; 00053 ip_addr_t addr; 00054 char *aliases; 00055 }; 00056 00057 /** h_errno is exported in netdb.h for access by applications. */ 00058 #if LWIP_DNS_API_DECLARE_H_ERRNO 00059 int h_errno; 00060 #endif /* LWIP_DNS_API_DECLARE_H_ERRNO */ 00061 00062 /** define "hostent" variables storage: 0 if we use a static (but unprotected) 00063 * set of variables for lwip_gethostbyname, 1 if we use a local storage */ 00064 #ifndef LWIP_DNS_API_HOSTENT_STORAGE 00065 #define LWIP_DNS_API_HOSTENT_STORAGE 0 00066 #endif 00067 00068 /** define "hostent" variables storage */ 00069 #if LWIP_DNS_API_HOSTENT_STORAGE 00070 #define HOSTENT_STORAGE 00071 #else 00072 #define HOSTENT_STORAGE static 00073 #endif /* LWIP_DNS_API_STATIC_HOSTENT */ 00074 00075 /** 00076 * Returns an entry containing addresses of address family AF_INET 00077 * for the host with name name. 00078 * Due to dns_gethostbyname limitations, only one address is returned. 00079 * 00080 * @param name the hostname to resolve 00081 * @return an entry containing addresses of address family AF_INET 00082 * for the host with name name 00083 */ 00084 struct hostent* 00085 lwip_gethostbyname(const char *name) 00086 { 00087 err_t err; 00088 ip_addr_t addr; 00089 00090 /* buffer variables for lwip_gethostbyname() */ 00091 HOSTENT_STORAGE struct hostent s_hostent; 00092 HOSTENT_STORAGE char *s_aliases; 00093 HOSTENT_STORAGE ip_addr_t s_hostent_addr; 00094 HOSTENT_STORAGE ip_addr_t *s_phostent_addr[2]; 00095 00096 /* query host IP address */ 00097 err = netconn_gethostbyname(name, &addr); 00098 if (err != ERR_OK) { 00099 LWIP_DEBUGF(DNS_DEBUG, ("lwip_gethostbyname(%s) failed, err=%d\n", name, err)); 00100 h_errno = HOST_NOT_FOUND; 00101 return NULL; 00102 } 00103 00104 /* fill hostent */ 00105 s_hostent_addr = addr; 00106 s_phostent_addr[0] = &s_hostent_addr; 00107 s_phostent_addr[1] = NULL; 00108 s_hostent.h_name = (char*)name; 00109 s_hostent.h_aliases = &s_aliases; 00110 s_hostent.h_addrtype = AF_INET; 00111 s_hostent.h_length = sizeof(ip_addr_t); 00112 s_hostent.h_addr_list = (char**)&s_phostent_addr; 00113 00114 #if DNS_DEBUG 00115 /* dump hostent */ 00116 LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_name == %s\n", s_hostent.h_name)); 00117 LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_aliases == %p\n", s_hostent.h_aliases)); 00118 if (s_hostent.h_aliases != NULL) { 00119 u8_t idx; 00120 for ( idx=0; s_hostent.h_aliases[idx]; idx++) { 00121 LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_aliases[%i]-> == %p\n", idx, s_hostent.h_aliases[idx])); 00122 LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_aliases[%i]-> == %s\n", idx, s_hostent.h_aliases[idx])); 00123 } 00124 } 00125 LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_addrtype == %d\n", s_hostent.h_addrtype)); 00126 LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_length == %d\n", s_hostent.h_length)); 00127 LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_addr_list == %p\n", s_hostent.h_addr_list)); 00128 if (s_hostent.h_addr_list != NULL) { 00129 u8_t idx; 00130 for ( idx=0; s_hostent.h_addr_list[idx]; idx++) { 00131 LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_addr_list[%i] == %p\n", idx, s_hostent.h_addr_list[idx])); 00132 LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_addr_list[%i]-> == %s\n", idx, ip_ntoa((ip_addr_t*)s_hostent.h_addr_list[idx]))); 00133 } 00134 } 00135 #endif /* DNS_DEBUG */ 00136 00137 #if LWIP_DNS_API_HOSTENT_STORAGE 00138 /* this function should return the "per-thread" hostent after copy from s_hostent */ 00139 return sys_thread_hostent(&s_hostent); 00140 #else 00141 return &s_hostent; 00142 #endif /* LWIP_DNS_API_HOSTENT_STORAGE */ 00143 } 00144 00145 /** 00146 * Thread-safe variant of lwip_gethostbyname: instead of using a static 00147 * buffer, this function takes buffer and errno pointers as arguments 00148 * and uses these for the result. 00149 * 00150 * @param name the hostname to resolve 00151 * @param ret pre-allocated struct where to store the result 00152 * @param buf pre-allocated buffer where to store additional data 00153 * @param buflen the size of buf 00154 * @param result pointer to a hostent pointer that is set to ret on success 00155 * and set to zero on error 00156 * @param h_errnop pointer to an int where to store errors (instead of modifying 00157 * the global h_errno) 00158 * @return 0 on success, non-zero on error, additional error information 00159 * is stored in *h_errnop instead of h_errno to be thread-safe 00160 */ 00161 int 00162 lwip_gethostbyname_r(const char *name, struct hostent *ret, char *buf, 00163 size_t buflen, struct hostent **result, int *h_errnop) 00164 { 00165 err_t err; 00166 struct gethostbyname_r_helper *h; 00167 char *hostname; 00168 size_t namelen; 00169 int lh_errno; 00170 00171 if (h_errnop == NULL) { 00172 /* ensure h_errnop is never NULL */ 00173 h_errnop = &lh_errno; 00174 } 00175 00176 if (result == NULL) { 00177 /* not all arguments given */ 00178 *h_errnop = EINVAL; 00179 return -1; 00180 } 00181 /* first thing to do: set *result to nothing */ 00182 *result = NULL; 00183 if ((name == NULL) || (ret == NULL) || (buf == 0)) { 00184 /* not all arguments given */ 00185 *h_errnop = EINVAL; 00186 return -1; 00187 } 00188 00189 namelen = strlen(name); 00190 if (buflen < (sizeof(struct gethostbyname_r_helper) + namelen + 1 + (MEM_ALIGNMENT - 1))) { 00191 /* buf can't hold the data needed + a copy of name */ 00192 *h_errnop = ERANGE; 00193 return -1; 00194 } 00195 00196 h = (struct gethostbyname_r_helper*)LWIP_MEM_ALIGN(buf); 00197 hostname = ((char*)h) + sizeof(struct gethostbyname_r_helper); 00198 00199 /* query host IP address */ 00200 err = netconn_gethostbyname(name, &(h->addr)); 00201 if (err != ERR_OK) { 00202 LWIP_DEBUGF(DNS_DEBUG, ("lwip_gethostbyname(%s) failed, err=%d\n", name, err)); 00203 *h_errnop = ENSRNOTFOUND; 00204 return -1; 00205 } 00206 00207 /* copy the hostname into buf */ 00208 MEMCPY(hostname, name, namelen); 00209 hostname[namelen] = 0; 00210 00211 /* fill hostent */ 00212 h->addrs = &(h->addr); 00213 h->aliases = NULL; 00214 ret->h_name = (char*)hostname; 00215 ret->h_aliases = &(h->aliases); 00216 ret->h_addrtype = AF_INET; 00217 ret->h_length = sizeof(ip_addr_t); 00218 ret->h_addr_list = (char**)&(h->addrs); 00219 00220 /* set result != NULL */ 00221 *result = ret; 00222 00223 /* return success */ 00224 return 0; 00225 } 00226 00227 /** 00228 * Frees one or more addrinfo structures returned by getaddrinfo(), along with 00229 * any additional storage associated with those structures. If the ai_next field 00230 * of the structure is not null, the entire list of structures is freed. 00231 * 00232 * @param ai struct addrinfo to free 00233 */ 00234 void 00235 lwip_freeaddrinfo(struct addrinfo *ai) 00236 { 00237 struct addrinfo *next; 00238 00239 while (ai != NULL) { 00240 next = ai->ai_next; 00241 memp_free(MEMP_NETDB, ai); 00242 ai = next; 00243 } 00244 } 00245 00246 /** 00247 * Translates the name of a service location (for example, a host name) and/or 00248 * a service name and returns a set of socket addresses and associated 00249 * information to be used in creating a socket with which to address the 00250 * specified service. 00251 * Memory for the result is allocated internally and must be freed by calling 00252 * lwip_freeaddrinfo()! 00253 * 00254 * Due to a limitation in dns_gethostbyname, only the first address of a 00255 * host is returned. 00256 * Also, service names are not supported (only port numbers)! 00257 * 00258 * @param nodename descriptive name or address string of the host 00259 * (may be NULL -> local address) 00260 * @param servname port number as string of NULL 00261 * @param hints structure containing input values that set socktype and protocol 00262 * @param res pointer to a pointer where to store the result (set to NULL on failure) 00263 * @return 0 on success, non-zero on failure 00264 */ 00265 int 00266 lwip_getaddrinfo(const char *nodename, const char *servname, 00267 const struct addrinfo *hints, struct addrinfo **res) 00268 { 00269 err_t err; 00270 ip_addr_t addr; 00271 struct addrinfo *ai; 00272 struct sockaddr_in *sa = NULL; 00273 int port_nr = 0; 00274 size_t total_size; 00275 size_t namelen = 0; 00276 00277 if (res == NULL) { 00278 return EAI_FAIL; 00279 } 00280 *res = NULL; 00281 if ((nodename == NULL) && (servname == NULL)) { 00282 return EAI_NONAME; 00283 } 00284 00285 if (servname != NULL) { 00286 /* service name specified: convert to port number 00287 * @todo?: currently, only ASCII integers (port numbers) are supported! */ 00288 port_nr = atoi(servname); 00289 if ((port_nr <= 0) || (port_nr > 0xffff)) { 00290 return EAI_SERVICE; 00291 } 00292 } 00293 00294 if (nodename != NULL) { 00295 /* service location specified, try to resolve */ 00296 err = netconn_gethostbyname(nodename, &addr); 00297 if (err != ERR_OK) { 00298 return EAI_FAIL; 00299 } 00300 } else { 00301 /* service location specified, use loopback address */ 00302 ip_addr_set_loopback(&addr); 00303 } 00304 00305 total_size = sizeof(struct addrinfo) + sizeof(struct sockaddr_in); 00306 if (nodename != NULL) { 00307 namelen = strlen(nodename); 00308 LWIP_ASSERT("namelen is too long", (namelen + 1) <= (mem_size_t)-1); 00309 total_size += namelen + 1; 00310 } 00311 /* If this fails, please report to lwip-devel! :-) */ 00312 LWIP_ASSERT("total_size <= NETDB_ELEM_SIZE: please report this!", 00313 total_size <= NETDB_ELEM_SIZE); 00314 ai = (struct addrinfo *)memp_malloc(MEMP_NETDB); 00315 if (ai == NULL) { 00316 goto memerr; 00317 } 00318 memset(ai, 0, total_size); 00319 sa = (struct sockaddr_in*)((u8_t*)ai + sizeof(struct addrinfo)); 00320 /* set up sockaddr */ 00321 inet_addr_from_ipaddr(&sa->sin_addr, &addr); 00322 sa->sin_family = AF_INET; 00323 sa->sin_len = sizeof(struct sockaddr_in); 00324 sa->sin_port = htons((u16_t)port_nr); 00325 00326 /* set up addrinfo */ 00327 ai->ai_family = AF_INET; 00328 if (hints != NULL) { 00329 /* copy socktype & protocol from hints if specified */ 00330 ai->ai_socktype = hints->ai_socktype; 00331 ai->ai_protocol = hints->ai_protocol; 00332 } 00333 if (nodename != NULL) { 00334 /* copy nodename to canonname if specified */ 00335 ai->ai_canonname = ((char*)ai + sizeof(struct addrinfo) + sizeof(struct sockaddr_in)); 00336 MEMCPY(ai->ai_canonname, nodename, namelen); 00337 ai->ai_canonname[namelen] = 0; 00338 } 00339 ai->ai_addrlen = sizeof(struct sockaddr_in); 00340 ai->ai_addr = (struct sockaddr*)sa; 00341 00342 *res = ai; 00343 00344 return 0; 00345 memerr: 00346 if (ai != NULL) { 00347 memp_free(MEMP_NETDB, ai); 00348 } 00349 return EAI_MEMORY; 00350 } 00351 00352 #endif /* LWIP_DNS && LWIP_SOCKET */
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