1 /**
2 * @file
3 * API functions for name resolving
4 *
5 * @defgroup netdbapi NETDB API
6 * @ingroup socket
7 */
8
9 /*
10 * Redistribution and use in source and binary forms, with or without modification,
11 * are permitted provided that the following conditions are met:
12 *
13 * 1. Redistributions of source code must retain the above copyright notice,
14 * this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright notice,
16 * this list of conditions and the following disclaimer in the documentation
17 * and/or other materials provided with the distribution.
18 * 3. The name of the author may not be used to endorse or promote products
19 * derived from this software without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
22 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
23 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
24 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
25 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
26 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
29 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
30 * OF SUCH DAMAGE.
31 *
32 * This file is part of the lwIP TCP/IP stack.
33 *
34 * Author: Simon Goldschmidt
35 *
36 */
37
38 #include "lwip/netdb.h"
39
40 #if LWIP_DNS && LWIP_SOCKET
41
42 #include "lwip/err.h"
43 #include "lwip/mem.h"
44 #include "lwip/memp.h"
45 #include "lwip/ip_addr.h"
46 #include "lwip/api.h"
47 #include "lwip/dns.h"
48
49 #include <string.h> /* memset */
50 #include <stdlib.h> /* atoi */
51
52 /** helper struct for gethostbyname_r to access the char* buffer */
53 struct gethostbyname_r_helper {
54 ip_addr_t *addr_list[2];
55 ip_addr_t addr;
56 char *aliases;
57 };
58
59 /** h_errno is exported in netdb.h for access by applications. */
60 #if LWIP_DNS_API_DECLARE_H_ERRNO
61 int h_errno;
62 #endif /* LWIP_DNS_API_DECLARE_H_ERRNO */
63
64 /** define "hostent" variables storage: 0 if we use a static (but unprotected)
65 * set of variables for lwip_gethostbyname, 1 if we use a local storage */
66 #ifndef LWIP_DNS_API_HOSTENT_STORAGE
67 #define LWIP_DNS_API_HOSTENT_STORAGE 0
68 #endif
69
70 /** define "hostent" variables storage */
71 #if LWIP_DNS_API_HOSTENT_STORAGE
72 #define HOSTENT_STORAGE
73 #else
74 #define HOSTENT_STORAGE static
75 #endif /* LWIP_DNS_API_STATIC_HOSTENT */
76
77 /**
78 * Returns an entry containing addresses of address family AF_INET
79 * for the host with name name.
80 * Due to dns_gethostbyname limitations, only one address is returned.
81 *
82 * @param name the hostname to resolve
83 * @return an entry containing addresses of address family AF_INET
84 * for the host with name name
85 */
86 struct hostent *
lwip_gethostbyname(const char * name)87 lwip_gethostbyname(const char *name)
88 {
89 err_t err;
90 ip_addr_t addr;
91
92 /* buffer variables for lwip_gethostbyname() */
93 HOSTENT_STORAGE struct hostent s_hostent;
94 HOSTENT_STORAGE char *s_aliases;
95 HOSTENT_STORAGE ip_addr_t s_hostent_addr;
96 HOSTENT_STORAGE ip_addr_t *s_phostent_addr[2];
97 HOSTENT_STORAGE char s_hostname[DNS_MAX_NAME_LENGTH + 1];
98
99 /* query host IP address */
100 err = netconn_gethostbyname(name, &addr);
101 if (err != ERR_OK) {
102 LWIP_DEBUGF(DNS_DEBUG, ("lwip_gethostbyname(%s) failed, err=%d\n", name, err));
103 h_errno = HOST_NOT_FOUND;
104 return NULL;
105 }
106
107 /* fill hostent */
108 s_hostent_addr = addr;
109 s_phostent_addr[0] = &s_hostent_addr;
110 s_phostent_addr[1] = NULL;
111 strncpy(s_hostname, name, DNS_MAX_NAME_LENGTH);
112 s_hostname[DNS_MAX_NAME_LENGTH] = 0;
113 s_hostent.h_name = s_hostname;
114 s_aliases = NULL;
115 s_hostent.h_aliases = &s_aliases;
116 s_hostent.h_addrtype = AF_INET;
117 s_hostent.h_length = sizeof(ip_addr_t);
118 s_hostent.h_addr_list = (char **)&s_phostent_addr;
119
120 #if DNS_DEBUG
121 /* dump hostent */
122 LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_name == %s\n", s_hostent.h_name));
123 LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_aliases == %p\n", (void *)s_hostent.h_aliases));
124 /* h_aliases are always empty */
125 LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_addrtype == %d\n", s_hostent.h_addrtype));
126 LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_length == %d\n", s_hostent.h_length));
127 LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_addr_list == %p\n", (void *)s_hostent.h_addr_list));
128 if (s_hostent.h_addr_list != NULL) {
129 u8_t idx;
130 for (idx = 0; s_hostent.h_addr_list[idx]; idx++) {
131 LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_addr_list[%i]-> == %s\n", idx, ipaddr_ntoa(s_phostent_addr[idx])));
132 }
133 }
134 #endif /* DNS_DEBUG */
135
136 #if LWIP_DNS_API_HOSTENT_STORAGE
137 /* this function should return the "per-thread" hostent after copy from s_hostent */
138 return sys_thread_hostent(&s_hostent);
139 #else
140 return &s_hostent;
141 #endif /* LWIP_DNS_API_HOSTENT_STORAGE */
142 }
143
144 /**
145 * Thread-safe variant of lwip_gethostbyname: instead of using a static
146 * buffer, this function takes buffer and errno pointers as arguments
147 * and uses these for the result.
148 *
149 * @param name the hostname to resolve
150 * @param ret pre-allocated struct where to store the result
151 * @param buf pre-allocated buffer where to store additional data
152 * @param buflen the size of buf
153 * @param result pointer to a hostent pointer that is set to ret on success
154 * and set to zero on error
155 * @param h_errnop pointer to an int where to store errors (instead of modifying
156 * the global h_errno)
157 * @return 0 on success, non-zero on error, additional error information
158 * is stored in *h_errnop instead of h_errno to be thread-safe
159 */
160 int
lwip_gethostbyname_r(const char * name,struct hostent * ret,char * buf,size_t buflen,struct hostent ** result,int * h_errnop)161 lwip_gethostbyname_r(const char *name, struct hostent *ret, char *buf,
162 size_t buflen, struct hostent **result, int *h_errnop)
163 {
164 err_t err;
165 struct gethostbyname_r_helper *h;
166 char *hostname;
167 size_t namelen;
168 int lh_errno;
169
170 if (h_errnop == NULL) {
171 /* ensure h_errnop is never NULL */
172 h_errnop = &lh_errno;
173 }
174
175 if (result == NULL) {
176 /* not all arguments given */
177 *h_errnop = EINVAL;
178 return -1;
179 }
180 /* first thing to do: set *result to nothing */
181 *result = NULL;
182 if ((name == NULL) || (ret == NULL) || (buf == NULL)) {
183 /* not all arguments given */
184 *h_errnop = EINVAL;
185 return -1;
186 }
187
188 namelen = strlen(name);
189 if (buflen < (sizeof(struct gethostbyname_r_helper) + LWIP_MEM_ALIGN_BUFFER(namelen + 1))) {
190 /* buf can't hold the data needed + a copy of name */
191 *h_errnop = ERANGE;
192 return -1;
193 }
194
195 h = (struct gethostbyname_r_helper *)LWIP_MEM_ALIGN(buf);
196 hostname = ((char *)h) + sizeof(struct gethostbyname_r_helper);
197
198 /* query host IP address */
199 err = netconn_gethostbyname(name, &h->addr);
200 if (err != ERR_OK) {
201 LWIP_DEBUGF(DNS_DEBUG, ("lwip_gethostbyname(%s) failed, err=%d\n", name, err));
202 *h_errnop = HOST_NOT_FOUND;
203 return -1;
204 }
205
206 /* copy the hostname into buf */
207 MEMCPY(hostname, name, namelen);
208 hostname[namelen] = 0;
209
210 /* fill hostent */
211 h->addr_list[0] = &h->addr;
212 h->addr_list[1] = NULL;
213 h->aliases = NULL;
214 ret->h_name = hostname;
215 ret->h_aliases = &h->aliases;
216 ret->h_addrtype = AF_INET;
217 ret->h_length = sizeof(ip_addr_t);
218 ret->h_addr_list = (char **)&h->addr_list;
219
220 /* set result != NULL */
221 *result = ret;
222
223 /* return success */
224 return 0;
225 }
226
227 /**
228 * Frees one or more addrinfo structures returned by getaddrinfo(), along with
229 * any additional storage associated with those structures. If the ai_next field
230 * of the structure is not null, the entire list of structures is freed.
231 *
232 * @param ai struct addrinfo to free
233 */
234 void
lwip_freeaddrinfo(struct addrinfo * ai)235 lwip_freeaddrinfo(struct addrinfo *ai)
236 {
237 struct addrinfo *next;
238
239 while (ai != NULL) {
240 next = ai->ai_next;
241 memp_free(MEMP_NETDB, ai);
242 ai = next;
243 }
244 }
245
246 /**
247 * Translates the name of a service location (for example, a host name) and/or
248 * a service name and returns a set of socket addresses and associated
249 * information to be used in creating a socket with which to address the
250 * specified service.
251 * Memory for the result is allocated internally and must be freed by calling
252 * lwip_freeaddrinfo()!
253 *
254 * Due to a limitation in dns_gethostbyname, only the first address of a
255 * host is returned.
256 * Also, service names are not supported (only port numbers)!
257 *
258 * @param nodename descriptive name or address string of the host
259 * (may be NULL -> local address)
260 * @param servname port number as string of NULL
261 * @param hints structure containing input values that set socktype and protocol
262 * @param res pointer to a pointer where to store the result (set to NULL on failure)
263 * @return 0 on success, non-zero on failure
264 *
265 * @todo: implement AI_V4MAPPED, AI_ADDRCONFIG
266 */
267 int
lwip_getaddrinfo(const char * nodename,const char * servname,const struct addrinfo * hints,struct addrinfo ** res)268 lwip_getaddrinfo(const char *nodename, const char *servname,
269 const struct addrinfo *hints, struct addrinfo **res)
270 {
271 err_t err;
272 ip_addr_t addr;
273 struct addrinfo *ai;
274 struct sockaddr_storage *sa = NULL;
275 int port_nr = 0;
276 size_t total_size;
277 size_t namelen = 0;
278 int ai_family;
279
280 if (res == NULL) {
281 return EAI_FAIL;
282 }
283 *res = NULL;
284 if ((nodename == NULL) && (servname == NULL)) {
285 return EAI_NONAME;
286 }
287
288 if (hints != NULL) {
289 ai_family = hints->ai_family;
290 if ((ai_family != AF_UNSPEC)
291 #if LWIP_IPV4
292 && (ai_family != AF_INET)
293 #endif /* LWIP_IPV4 */
294 #if LWIP_IPV6
295 && (ai_family != AF_INET6)
296 #endif /* LWIP_IPV6 */
297 ) {
298 return EAI_FAMILY;
299 }
300 } else {
301 ai_family = AF_UNSPEC;
302 }
303
304 if (servname != NULL) {
305 /* service name specified: convert to port number
306 * @todo?: currently, only ASCII integers (port numbers) are supported (AI_NUMERICSERV)! */
307 port_nr = atoi(servname);
308 if (port_nr == 0 && (servname[0] != '0')) {
309 /* atoi failed - service was not numeric */
310 return EAI_SERVICE;
311 }
312 if ((port_nr < 0) || (port_nr > 0xffff)) {
313 return EAI_SERVICE;
314 }
315 }
316
317 if (nodename != NULL) {
318 /* service location specified, try to resolve */
319 if ((hints != NULL) && (hints->ai_flags & AI_NUMERICHOST)) {
320 /* no DNS lookup, just parse for an address string */
321 if (!ipaddr_aton(nodename, &addr)) {
322 return EAI_NONAME;
323 }
324 #if LWIP_IPV4 && LWIP_IPV6
325 if ((IP_IS_V6_VAL(addr) && ai_family == AF_INET) ||
326 (IP_IS_V4_VAL(addr) && ai_family == AF_INET6)) {
327 return EAI_NONAME;
328 }
329 #endif /* LWIP_IPV4 && LWIP_IPV6 */
330 } else {
331 #if LWIP_IPV4 && LWIP_IPV6
332 /* AF_UNSPEC: prefer IPv4 */
333 u8_t type = NETCONN_DNS_IPV4_IPV6;
334 if (ai_family == AF_INET) {
335 type = NETCONN_DNS_IPV4;
336 } else if (ai_family == AF_INET6) {
337 type = NETCONN_DNS_IPV6;
338 }
339 #endif /* LWIP_IPV4 && LWIP_IPV6 */
340 err = netconn_gethostbyname_addrtype(nodename, &addr, type);
341 if (err != ERR_OK) {
342 return EAI_FAIL;
343 }
344 }
345 } else {
346 /* service location specified, use loopback address */
347 if ((hints != NULL) && (hints->ai_flags & AI_PASSIVE)) {
348 ip_addr_set_any_val(ai_family == AF_INET6, addr);
349 } else {
350 ip_addr_set_loopback_val(ai_family == AF_INET6, addr);
351 }
352 }
353
354 total_size = sizeof(struct addrinfo) + sizeof(struct sockaddr_storage);
355 if (nodename != NULL) {
356 namelen = strlen(nodename);
357 if (namelen > DNS_MAX_NAME_LENGTH) {
358 /* invalid name length */
359 return EAI_FAIL;
360 }
361 LWIP_ASSERT("namelen is too long", total_size + namelen + 1 > total_size);
362 total_size += namelen + 1;
363 }
364 /* If this fails, please report to lwip-devel! :-) */
365 LWIP_ASSERT("total_size <= NETDB_ELEM_SIZE: please report this!",
366 total_size <= NETDB_ELEM_SIZE);
367 ai = (struct addrinfo *)memp_malloc(MEMP_NETDB);
368 if (ai == NULL) {
369 return EAI_MEMORY;
370 }
371 memset(ai, 0, total_size);
372 /* cast through void* to get rid of alignment warnings */
373 sa = (struct sockaddr_storage *)(void *)((u8_t *)ai + sizeof(struct addrinfo));
374 if (IP_IS_V6_VAL(addr)) {
375 #if LWIP_IPV6
376 struct sockaddr_in6 *sa6 = (struct sockaddr_in6 *)sa;
377 /* set up sockaddr */
378 inet6_addr_from_ip6addr(&sa6->sin6_addr, ip_2_ip6(&addr));
379 sa6->sin6_family = AF_INET6;
380 sa6->sin6_len = sizeof(struct sockaddr_in6);
381 sa6->sin6_port = lwip_htons((u16_t)port_nr);
382 sa6->sin6_scope_id = ip6_addr_zone(ip_2_ip6(&addr));
383 ai->ai_family = AF_INET6;
384 ai->ai_addrlen = sizeof(struct sockaddr_in6);
385 #endif /* LWIP_IPV6 */
386 } else {
387 #if LWIP_IPV4
388 struct sockaddr_in *sa4 = (struct sockaddr_in *)sa;
389 /* set up sockaddr */
390 inet_addr_from_ip4addr(&sa4->sin_addr, ip_2_ip4(&addr));
391 sa4->sin_family = AF_INET;
392 sa4->sin_len = sizeof(struct sockaddr_in);
393 sa4->sin_port = lwip_htons((u16_t)port_nr);
394 ai->ai_family = AF_INET;
395 ai->ai_addrlen = sizeof(struct sockaddr_in);
396 #endif /* LWIP_IPV4 */
397 }
398
399 /* set up addrinfo */
400 if (hints != NULL) {
401 /* copy socktype & protocol from hints if specified */
402 ai->ai_socktype = hints->ai_socktype;
403 ai->ai_protocol = hints->ai_protocol;
404 }
405 if (nodename != NULL) {
406 /* copy nodename to canonname if specified */
407 ai->ai_canonname = ((char *)ai + sizeof(struct addrinfo) + sizeof(struct sockaddr_storage));
408 MEMCPY(ai->ai_canonname, nodename, namelen);
409 ai->ai_canonname[namelen] = 0;
410 }
411 ai->ai_addr = (struct sockaddr *)sa;
412
413 *res = ai;
414
415 return 0;
416 }
417
418 #endif /* LWIP_DNS && LWIP_SOCKET */
419