minix/lib/liblwip/dist/src/api/netdb.c

   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*
  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]   == %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  */
 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 == 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) + LWIP_MEM_ALIGN_BUFFER(namelen + 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  */
 235 void
 236 lwip_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  */
 268 int
 269 lwip_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     sa6->sin6_scope_id = ip6_addr_zone(ip_2_ip6(&addr));
 380     ai->ai_family = AF_INET6;
 381 #endif /* LWIP_IPV6 */
 382   } else {
 383 #if LWIP_IPV4
 384     struct sockaddr_in *sa4 = (struct sockaddr_in*)sa;
 385     /* set up sockaddr */
 386     inet_addr_from_ip4addr(&sa4->sin_addr, ip_2_ip4(&addr));
 387     sa4->sin_family = AF_INET;
 388     sa4->sin_len = sizeof(struct sockaddr_in);
 389     sa4->sin_port = lwip_htons((u16_t)port_nr);
 390     ai->ai_family = AF_INET;
 391 #endif /* LWIP_IPV4 */
 392   }
 393
 394   /* set up addrinfo */
 395   if (hints != NULL) {
 396     /* copy socktype & protocol from hints if specified */
 397     ai->ai_socktype = hints->ai_socktype;
 398     ai->ai_protocol = hints->ai_protocol;
 399   }
 400   if (nodename != NULL) {
 401     /* copy nodename to canonname if specified */
 402     ai->ai_canonname = ((char*)ai + sizeof(struct addrinfo) + sizeof(struct sockaddr_storage));
 403     MEMCPY(ai->ai_canonname, nodename, namelen);
 404     ai->ai_canonname[namelen] = 0;
 405   }
 406   ai->ai_addrlen = sizeof(struct sockaddr_storage);
 407   ai->ai_addr = (struct sockaddr*)sa;
 408
 409   *res = ai;
 410
 411   return 0;
 412 }
 413
 414 #endif /* LWIP_DNS && LWIP_SOCKET */