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 */
53struct 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
61int 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 */
86struct hostent*
87lwip_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]   == %p\n", idx, s_hostent.h_addr_list[idx]));
132      LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_addr_list[%i]-> == %s\n", idx, ipaddr_ntoa((ip_addr_t*)s_hostent.h_addr_list[idx])));
133    }
134  }
135#endif /* DNS_DEBUG */
136
137#if LWIP_DNS_API_HOSTENT_STORAGE
138  /* this function should return the "per-thread" hostent after copy from s_hostent */
139  return sys_thread_hostent(&s_hostent);
140#else
141  return &s_hostent;
142#endif /* LWIP_DNS_API_HOSTENT_STORAGE */
143}
144
145/**
146 * Thread-safe variant of lwip_gethostbyname: instead of using a static
147 * buffer, this function takes buffer and errno pointers as arguments
148 * and uses these for the result.
149 *
150 * @param name the hostname to resolve
151 * @param ret pre-allocated struct where to store the result
152 * @param buf pre-allocated buffer where to store additional data
153 * @param buflen the size of buf
154 * @param result pointer to a hostent pointer that is set to ret on success
155 *               and set to zero on error
156 * @param h_errnop pointer to an int where to store errors (instead of modifying
157 *                 the global h_errno)
158 * @return 0 on success, non-zero on error, additional error information
159 *         is stored in *h_errnop instead of h_errno to be thread-safe
160 */
161int
162lwip_gethostbyname_r(const char *name, struct hostent *ret, char *buf,
163                size_t buflen, struct hostent **result, int *h_errnop)
164{
165  err_t err;
166  struct gethostbyname_r_helper *h;
167  char *hostname;
168  size_t namelen;
169  int lh_errno;
170
171  if (h_errnop == NULL) {
172    /* ensure h_errnop is never NULL */
173    h_errnop = &lh_errno;
174  }
175
176  if (result == NULL) {
177    /* not all arguments given */
178    *h_errnop = EINVAL;
179    return -1;
180  }
181  /* first thing to do: set *result to nothing */
182  *result = NULL;
183  if ((name == NULL) || (ret == NULL) || (buf == NULL)) {
184    /* not all arguments given */
185    *h_errnop = EINVAL;
186    return -1;
187  }
188
189  namelen = strlen(name);
190  if (buflen < (sizeof(struct gethostbyname_r_helper) + namelen + 1 + (MEM_ALIGNMENT - 1))) {
191    /* buf can't hold the data needed + a copy of name */
192    *h_errnop = ERANGE;
193    return -1;
194  }
195
196  h = (struct gethostbyname_r_helper*)LWIP_MEM_ALIGN(buf);
197  hostname = ((char*)h) + sizeof(struct gethostbyname_r_helper);
198
199  /* query host IP address */
200  err = netconn_gethostbyname(name, &h->addr);
201  if (err != ERR_OK) {
202    LWIP_DEBUGF(DNS_DEBUG, ("lwip_gethostbyname(%s) failed, err=%d\n", name, err));
203    *h_errnop = HOST_NOT_FOUND;
204    return -1;
205  }
206
207  /* copy the hostname into buf */
208  MEMCPY(hostname, name, namelen);
209  hostname[namelen] = 0;
210
211  /* fill hostent */
212  h->addr_list[0] = &h->addr;
213  h->addr_list[1] = NULL;
214  h->aliases = NULL;
215  ret->h_name = hostname;
216  ret->h_aliases = &h->aliases;
217  ret->h_addrtype = AF_INET;
218  ret->h_length = sizeof(ip_addr_t);
219  ret->h_addr_list = (char**)&h->addr_list;
220
221  /* set result != NULL */
222  *result = ret;
223
224  /* return success */
225  return 0;
226}
227
228/**
229 * Frees one or more addrinfo structures returned by getaddrinfo(), along with
230 * any additional storage associated with those structures. If the ai_next field
231 * of the structure is not null, the entire list of structures is freed.
232 *
233 * @param ai struct addrinfo to free
234 */
235void
236lwip_freeaddrinfo(struct addrinfo *ai)
237{
238  struct addrinfo *next;
239
240  while (ai != NULL) {
241    next = ai->ai_next;
242    memp_free(MEMP_NETDB, ai);
243    ai = next;
244  }
245}
246
247/**
248 * Translates the name of a service location (for example, a host name) and/or
249 * a service name and returns a set of socket addresses and associated
250 * information to be used in creating a socket with which to address the
251 * specified service.
252 * Memory for the result is allocated internally and must be freed by calling
253 * lwip_freeaddrinfo()!
254 *
255 * Due to a limitation in dns_gethostbyname, only the first address of a
256 * host is returned.
257 * Also, service names are not supported (only port numbers)!
258 *
259 * @param nodename descriptive name or address string of the host
260 *                 (may be NULL -> local address)
261 * @param servname port number as string of NULL
262 * @param hints structure containing input values that set socktype and protocol
263 * @param res pointer to a pointer where to store the result (set to NULL on failure)
264 * @return 0 on success, non-zero on failure
265 *
266 * @todo: implement AI_V4MAPPED, AI_ADDRCONFIG
267 */
268int
269lwip_getaddrinfo(const char *nodename, const char *servname,
270       const struct addrinfo *hints, struct addrinfo **res)
271{
272  err_t err;
273  ip_addr_t addr;
274  struct addrinfo *ai;
275  struct sockaddr_storage *sa = NULL;
276  int port_nr = 0;
277  size_t total_size;
278  size_t namelen = 0;
279  int ai_family;
280
281  if (res == NULL) {
282    return EAI_FAIL;
283  }
284  *res = NULL;
285  if ((nodename == NULL) && (servname == NULL)) {
286    return EAI_NONAME;
287  }
288
289  if (hints != NULL) {
290    ai_family = hints->ai_family;
291    if ((ai_family != AF_UNSPEC)
292#if LWIP_IPV4
293      && (ai_family != AF_INET)
294#endif /* LWIP_IPV4 */
295#if LWIP_IPV6
296      && (ai_family != AF_INET6)
297#endif /* LWIP_IPV6 */
298      ) {
299      return EAI_FAMILY;
300    }
301  } else {
302    ai_family = AF_UNSPEC;
303  }
304
305  if (servname != NULL) {
306    /* service name specified: convert to port number
307     * @todo?: currently, only ASCII integers (port numbers) are supported (AI_NUMERICSERV)! */
308    port_nr = atoi(servname);
309    if ((port_nr <= 0) || (port_nr > 0xffff)) {
310      return EAI_SERVICE;
311    }
312  }
313
314  if (nodename != NULL) {
315    /* service location specified, try to resolve */
316    if ((hints != NULL) && (hints->ai_flags & AI_NUMERICHOST)) {
317      /* no DNS lookup, just parse for an address string */
318      if (!ipaddr_aton(nodename, &addr)) {
319        return EAI_NONAME;
320      }
321#if LWIP_IPV4 && LWIP_IPV6
322      if ((IP_IS_V6_VAL(addr) && ai_family == AF_INET) ||
323          (IP_IS_V4_VAL(addr) && ai_family == AF_INET6)) {
324        return EAI_NONAME;
325      }
326#endif /* LWIP_IPV4 && LWIP_IPV6 */
327    } else {
328#if LWIP_IPV4 && LWIP_IPV6
329      /* AF_UNSPEC: prefer IPv4 */
330      u8_t type = NETCONN_DNS_IPV4_IPV6;
331      if (ai_family == AF_INET) {
332        type = NETCONN_DNS_IPV4;
333      } else if (ai_family == AF_INET6) {
334        type = NETCONN_DNS_IPV6;
335      }
336#endif /* LWIP_IPV4 && LWIP_IPV6 */
337      err = netconn_gethostbyname_addrtype(nodename, &addr, type);
338      if (err != ERR_OK) {
339        return EAI_FAIL;
340      }
341    }
342  } else {
343    /* service location specified, use loopback address */
344    if ((hints != NULL) && (hints->ai_flags & AI_PASSIVE)) {
345      ip_addr_set_any(ai_family == AF_INET6, &addr);
346    } else {
347      ip_addr_set_loopback(ai_family == AF_INET6, &addr);
348    }
349  }
350
351  total_size = sizeof(struct addrinfo) + sizeof(struct sockaddr_storage);
352  if (nodename != NULL) {
353    namelen = strlen(nodename);
354    if (namelen > DNS_MAX_NAME_LENGTH) {
355      /* invalid name length */
356      return EAI_FAIL;
357    }
358    LWIP_ASSERT("namelen is too long", total_size + namelen + 1 > total_size);
359    total_size += namelen + 1;
360  }
361  /* If this fails, please report to lwip-devel! :-) */
362  LWIP_ASSERT("total_size <= NETDB_ELEM_SIZE: please report this!",
363    total_size <= NETDB_ELEM_SIZE);
364  ai = (struct addrinfo *)memp_malloc(MEMP_NETDB);
365  if (ai == NULL) {
366    return EAI_MEMORY;
367  }
368  memset(ai, 0, total_size);
369  /* cast through void* to get rid of alignment warnings */
370  sa = (struct sockaddr_storage *)(void*)((u8_t*)ai + sizeof(struct addrinfo));
371  if (IP_IS_V6_VAL(addr)) {
372#if LWIP_IPV6
373    struct sockaddr_in6 *sa6 = (struct sockaddr_in6*)sa;
374    /* set up sockaddr */
375    inet6_addr_from_ip6addr(&sa6->sin6_addr, ip_2_ip6(&addr));
376    sa6->sin6_family = AF_INET6;
377    sa6->sin6_len = sizeof(struct sockaddr_in6);
378    sa6->sin6_port = lwip_htons((u16_t)port_nr);
379    ai->ai_family = AF_INET6;
380#endif /* LWIP_IPV6 */
381  } else {
382#if LWIP_IPV4
383    struct sockaddr_in *sa4 = (struct sockaddr_in*)sa;
384    /* set up sockaddr */
385    inet_addr_from_ip4addr(&sa4->sin_addr, ip_2_ip4(&addr));
386    sa4->sin_family = AF_INET;
387    sa4->sin_len = sizeof(struct sockaddr_in);
388    sa4->sin_port = lwip_htons((u16_t)port_nr);
389    ai->ai_family = AF_INET;
390#endif /* LWIP_IPV4 */
391  }
392
393  /* set up addrinfo */
394  if (hints != NULL) {
395    /* copy socktype & protocol from hints if specified */
396    ai->ai_socktype = hints->ai_socktype;
397    ai->ai_protocol = hints->ai_protocol;
398  }
399  if (nodename != NULL) {
400    /* copy nodename to canonname if specified */
401    ai->ai_canonname = ((char*)ai + sizeof(struct addrinfo) + sizeof(struct sockaddr_storage));
402    MEMCPY(ai->ai_canonname, nodename, namelen);
403    ai->ai_canonname[namelen] = 0;
404  }
405  ai->ai_addrlen = sizeof(struct sockaddr_storage);
406  ai->ai_addr = (struct sockaddr*)sa;
407
408  *res = ai;
409
410  return 0;
411}
412
413#endif /* LWIP_DNS && LWIP_SOCKET */
414