lib/liblwip/api/netdb.c

   1 /**
   2  * @file
   3  * API functions for name resolving
   4  *
   5  */
   6
   7 /*
   8  * Redistribution and use in source and binary forms, with or without modification,
   9  * are permitted provided that the following conditions are met:
  10  *
  11  * 1. Redistributions of source code must retain the above copyright notice,
  12  *    this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright notice,
  14  *    this list of conditions and the following disclaimer in the documentation
  15  *    and/or other materials provided with the distribution.
  16  * 3. The name of the author may not be used to endorse or promote products
  17  *    derived from this software without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
  20  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
  21  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
  22  * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  23  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
  24  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  25  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  26  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
  27  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
  28  * OF SUCH DAMAGE.
  29  *
  30  * This file is part of the lwIP TCP/IP stack.
  31  *
  32  * Author: Simon Goldschmidt
  33  *
  34  */
  35
  36 #include "lwip/netdb.h"
  37
  38 #if LWIP_DNS && LWIP_SOCKET
  39
  40 #include "lwip/err.h"
  41 #include "lwip/mem.h"
  42 #include "lwip/memp.h"
  43 #include "lwip/ip_addr.h"
  44 #include "lwip/api.h"
  45 #include "lwip/dns.h"
  46
  47 #include <string.h>
  48 #include <stdlib.h>
  49
  50 /** helper struct for gethostbyname_r to access the char* buffer */
  51 struct gethostbyname_r_helper {
  52   ip_addr_t *addrs;
  53   ip_addr_t addr;
  54   char *aliases;
  55 };
  56
  57 /** h_errno is exported in netdb.h for access by applications. */
  58 #if LWIP_DNS_API_DECLARE_H_ERRNO
  59 int h_errno;
  60 #endif /* LWIP_DNS_API_DECLARE_H_ERRNO */
  61
  62 /** define "hostent" variables storage: 0 if we use a static (but unprotected)
  63  * set of variables for lwip_gethostbyname, 1 if we use a local storage */
  64 #ifndef LWIP_DNS_API_HOSTENT_STORAGE
  65 #define LWIP_DNS_API_HOSTENT_STORAGE 0
  66 #endif
  67
  68 /** define "hostent" variables storage */
  69 #if LWIP_DNS_API_HOSTENT_STORAGE
  70 #define HOSTENT_STORAGE
  71 #else
  72 #define HOSTENT_STORAGE static
  73 #endif /* LWIP_DNS_API_STATIC_HOSTENT */
  74
  75 /**
  76  * Returns an entry containing addresses of address family AF_INET
  77  * for the host with name name.
  78  * Due to dns_gethostbyname limitations, only one address is returned.
  79  *
  80  * @param name the hostname to resolve
  81  * @return an entry containing addresses of address family AF_INET
  82  *         for the host with name name
  83  */
  84 struct hostent*
  85 lwip_gethostbyname(const char *name)
  86 {
  87   err_t err;
  88   ip_addr_t addr;
  89
  90   /* buffer variables for lwip_gethostbyname() */
  91   HOSTENT_STORAGE struct hostent s_hostent;
  92   HOSTENT_STORAGE char *s_aliases;
  93   HOSTENT_STORAGE ip_addr_t s_hostent_addr;
  94   HOSTENT_STORAGE ip_addr_t *s_phostent_addr[2];
  95
  96   /* query host IP address */
  97   err = netconn_gethostbyname(name, &addr);
  98   if (err != ERR_OK) {
  99     LWIP_DEBUGF(DNS_DEBUG, ("lwip_gethostbyname(%s) failed, err=%d\n", name, err));
 100     h_errno = HOST_NOT_FOUND;
 101     return NULL;
 102   }
 103
 104   /* fill hostent */
 105   s_hostent_addr = addr;
 106   s_phostent_addr[0] = &s_hostent_addr;
 107   s_phostent_addr[1] = NULL;
 108   s_hostent.h_name = (char*)name;
 109   s_hostent.h_aliases = &s_aliases;
 110   s_hostent.h_addrtype = AF_INET;
 111   s_hostent.h_length = sizeof(ip_addr_t);
 112   s_hostent.h_addr_list = (char**)&s_phostent_addr;
 113
 114 #if DNS_DEBUG
 115   /* dump hostent */
 116   LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_name           == %s\n", s_hostent.h_name));
 117   LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_aliases        == %p\n", s_hostent.h_aliases));
 118   if (s_hostent.h_aliases != NULL) {
 119     u8_t idx;
 120     for ( idx=0; s_hostent.h_aliases[idx]; idx++) {
 121       LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_aliases[%i]->   == %p\n", idx, s_hostent.h_aliases[idx]));
 122       LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_aliases[%i]->   == %s\n", idx, s_hostent.h_aliases[idx]));
 123     }
 124   }
 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", 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, ip_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  */
 161 int
 162 lwip_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 == 0)) {
 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 = ENSRNOTFOUND;
 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->addrs = &(h->addr);
 213   h->aliases = NULL;
 214   ret->h_name = (char*)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->addrs);
 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
 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 int
 266 lwip_getaddrinfo(const char *nodename, const char *servname,
 267        const struct addrinfo *hints, struct addrinfo **res)
 268 {
 269   err_t err;
 270   ip_addr_t addr;
 271   struct addrinfo *ai;
 272   struct sockaddr_in *sa = NULL;
 273   int port_nr = 0;
 274   size_t total_size;
 275   size_t namelen = 0;
 276
 277   if (res == NULL) {
 278     return EAI_FAIL;
 279   }
 280   *res = NULL;
 281   if ((nodename == NULL) && (servname == NULL)) {
 282     return EAI_NONAME;
 283   }
 284
 285   if (servname != NULL) {
 286     /* service name specified: convert to port number
 287      * @todo?: currently, only ASCII integers (port numbers) are supported! */
 288     port_nr = atoi(servname);
 289     if ((port_nr <= 0) || (port_nr > 0xffff)) {
 290       return EAI_SERVICE;
 291     }
 292   }
 293
 294   if (nodename != NULL) {
 295     /* service location specified, try to resolve */
 296     err = netconn_gethostbyname(nodename, &addr);
 297     if (err != ERR_OK) {
 298       return EAI_FAIL;
 299     }
 300   } else {
 301     /* service location specified, use loopback address */
 302     ip_addr_set_loopback(&addr);
 303   }
 304
 305   total_size = sizeof(struct addrinfo) + sizeof(struct sockaddr_in);
 306   if (nodename != NULL) {
 307     namelen = strlen(nodename);
 308     LWIP_ASSERT("namelen is too long", (namelen + 1) <= (mem_size_t)-1);
 309     total_size += namelen + 1;
 310   }
 311   /* If this fails, please report to lwip-devel! :-) */
 312   LWIP_ASSERT("total_size <= NETDB_ELEM_SIZE: please report this!",
 313     total_size <= NETDB_ELEM_SIZE);
 314   ai = (struct addrinfo *)memp_malloc(MEMP_NETDB);
 315   if (ai == NULL) {
 316     goto memerr;
 317   }
 318   memset(ai, 0, total_size);
 319   sa = (struct sockaddr_in*)((u8_t*)ai + sizeof(struct addrinfo));
 320   /* set up sockaddr */
 321   inet_addr_from_ipaddr(&sa->sin_addr, &addr);
 322   sa->sin_family = AF_INET;
 323   sa->sin_len = sizeof(struct sockaddr_in);
 324   sa->sin_port = htons((u16_t)port_nr);
 325
 326   /* set up addrinfo */
 327   ai->ai_family = AF_INET;
 328   if (hints != NULL) {
 329     /* copy socktype & protocol from hints if specified */
 330     ai->ai_socktype = hints->ai_socktype;
 331     ai->ai_protocol = hints->ai_protocol;
 332   }
 333   if (nodename != NULL) {
 334     /* copy nodename to canonname if specified */
 335     ai->ai_canonname = ((char*)ai + sizeof(struct addrinfo) + sizeof(struct sockaddr_in));
 336     MEMCPY(ai->ai_canonname, nodename, namelen);
 337     ai->ai_canonname[namelen] = 0;
 338   }
 339   ai->ai_addrlen = sizeof(struct sockaddr_in);
 340   ai->ai_addr = (struct sockaddr*)sa;
 341
 342   *res = ai;
 343
 344   return 0;
 345 memerr:
 346   if (ai != NULL) {
 347     memp_free(MEMP_NETDB, ai);
 348   }
 349   return EAI_MEMORY;
 350 }
 351
 352 #endif /* LWIP_DNS && LWIP_SOCKET */