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/ip_addr.h"
00043 #include "lwip/api.h"
00044 
00045 /** helper struct for gethostbyname_r to access the char* buffer */
00046 struct gethostbyname_r_helper {
00047   struct ip_addr *addrs;
00048   struct ip_addr addr;
00049   char *aliases;
00050 };
00051 
00052 /** h_errno is exported in netdb.h for access by applications. */
00053 #if LWIP_DNS_API_DECLARE_H_ERRNO
00054 int h_errno;
00055 #endif /* LWIP_DNS_API_DECLARE_H_ERRNO */
00056 
00057 /** define "hostent" variables storage: 0 if we use a static (but unprotected)
00058  * set of variables for lwip_gethostbyname, 1 if we use a local storage */
00059 #ifndef LWIP_DNS_API_HOSTENT_STORAGE
00060 #define LWIP_DNS_API_HOSTENT_STORAGE 0
00061 #endif
00062 
00063 /** define "hostent" variables storage */
00064 #if LWIP_DNS_API_HOSTENT_STORAGE
00065 #define HOSTENT_STORAGE
00066 #else
00067 #define HOSTENT_STORAGE static
00068 #endif /* LWIP_DNS_API_STATIC_HOSTENT */
00069 
00070 /**
00071  * Returns an entry containing addresses of address family AF_INET
00072  * for the host with name name.
00073  * Due to dns_gethostbyname limitations, only one address is returned.
00074  *
00075  * @param name the hostname to resolve
00076  * @return an entry containing addresses of address family AF_INET
00077  *         for the host with name name
00078  */
00079 struct hostent*
00080 lwip_gethostbyname(const char *name)
00081 {
00082   err_t err;
00083   struct ip_addr addr;
00084 
00085   /* buffer variables for lwip_gethostbyname() */
00086   HOSTENT_STORAGE struct hostent s_hostent;
00087   HOSTENT_STORAGE char *s_aliases;
00088   HOSTENT_STORAGE struct ip_addr s_hostent_addr;
00089   HOSTENT_STORAGE struct ip_addr *s_phostent_addr;
00090 
00091   /* query host IP address */
00092   err = netconn_gethostbyname(name, &addr);
00093   if (err != ERR_OK) {
00094     LWIP_DEBUGF(DNS_DEBUG, ("lwip_gethostbyname(%s) failed, err=%d\n", name, err));
00095     h_errno = HOST_NOT_FOUND;
00096     return NULL;
00097   }
00098 
00099   /* fill hostent */
00100   s_hostent_addr = addr;
00101   s_phostent_addr = &s_hostent_addr;
00102   s_hostent.h_name = (char*)name;
00103   s_hostent.h_aliases = &s_aliases;
00104   s_hostent.h_addrtype = AF_INET;
00105   s_hostent.h_length = sizeof(struct ip_addr);
00106   s_hostent.h_addr_list = (char**)&s_phostent_addr;
00107 
00108 #if DNS_DEBUG
00109   /* dump hostent */
00110   LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_name           == %s\n",      s_hostent.h_name));
00111   LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_aliases        == 0x%08lX\n",(u32_t)(s_hostent.h_aliases)));
00112   if (s_hostent.h_aliases != NULL) {
00113     u8_t idx;
00114     for ( idx=0; s_hostent.h_aliases[idx]; idx++) {
00115       LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_aliases[%i]->   == 0x%08lX\n", idx, s_hostent.h_aliases[idx]));
00116       LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_aliases[%i]->   == %s\n",      idx, s_hostent.h_aliases[idx]));
00117     }
00118   }
00119   LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_addrtype       == %lu\n",    (u32_t)(s_hostent.h_addrtype)));
00120   LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_length         == %lu\n",    (u32_t)(s_hostent.h_length)));
00121   LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_addr_list      == 0x%08lX\n", s_hostent.h_addr_list));
00122   if (s_hostent.h_addr_list != NULL) {
00123     u8_t idx;
00124     for ( idx=0; s_hostent.h_addr_list[idx]; idx++) {
00125       LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_addr_list[%i]   == 0x%08lX\n", idx, s_hostent.h_addr_list[idx]));
00126       LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_addr_list[%i]-> == %s\n",      idx, inet_ntoa(*((struct in_addr*)(s_hostent.h_addr_list[idx])))));
00127     }
00128   }
00129 #endif /* DNS_DEBUG */
00130 
00131 #if LWIP_DNS_API_HOSTENT_STORAGE
00132   /* this function should return the "per-thread" hostent after copy from s_hostent */
00133   return sys_thread_hostent(&s_hostent);
00134 #else
00135   return &s_hostent;
00136 #endif /* LWIP_DNS_API_HOSTENT_STORAGE */
00137 }
00138 
00139 /**
00140  * Thread-safe variant of lwip_gethostbyname: instead of using a static
00141  * buffer, this function takes buffer and errno pointers as arguments
00142  * and uses these for the result.
00143  *
00144  * @param name the hostname to resolve
00145  * @param ret pre-allocated struct where to store the result
00146  * @param buf pre-allocated buffer where to store additional data
00147  * @param buflen the size of buf
00148  * @param result pointer to a hostent pointer that is set to ret on success
00149  *               and set to zero on error
00150  * @param h_errnop pointer to an int where to store errors (instead of modifying
00151  *                 the global h_errno)
00152  * @return 0 on success, non-zero on error, additional error information
00153  *         is stored in *h_errnop instead of h_errno to be thread-safe
00154  */
00155 int
00156 lwip_gethostbyname_r(const char *name, struct hostent *ret, char *buf,
00157                 size_t buflen, struct hostent **result, int *h_errnop)
00158 {
00159   err_t err;
00160   struct gethostbyname_r_helper *h;
00161   char *hostname;
00162   size_t namelen;
00163   int lh_errno;
00164 
00165   if (h_errnop == NULL) {
00166     /* ensure h_errnop is never NULL */
00167     h_errnop = &lh_errno;
00168   }
00169 
00170   if (result == NULL) {
00171     /* not all arguments given */
00172     *h_errnop = EINVAL;
00173     return -1;
00174   }
00175   /* first thing to do: set *result to nothing */
00176   *result = NULL;
00177   if ((name == NULL) || (ret == NULL) || (buf == 0)) {
00178     /* not all arguments given */
00179     *h_errnop = EINVAL;
00180     return -1;
00181   }
00182 
00183   namelen = strlen(name);
00184   if (buflen < (sizeof(struct gethostbyname_r_helper) + namelen + 1 + (MEM_ALIGNMENT - 1))) {
00185     /* buf can't hold the data needed + a copy of name */
00186     *h_errnop = ERANGE;
00187     return -1;
00188   }
00189 
00190   h = (struct gethostbyname_r_helper*)LWIP_MEM_ALIGN(buf);
00191   hostname = ((char*)h) + sizeof(struct gethostbyname_r_helper);
00192 
00193   /* query host IP address */
00194   err = netconn_gethostbyname(name, &(h->addr));
00195   if (err != ERR_OK) {
00196     LWIP_DEBUGF(DNS_DEBUG, ("lwip_gethostbyname(%s) failed, err=%d\n", name, err));
00197     *h_errnop = ENSRNOTFOUND;
00198     return -1;
00199   }
00200 
00201   /* copy the hostname into buf */
00202   MEMCPY(hostname, name, namelen);
00203   hostname[namelen] = 0;
00204 
00205   /* fill hostent */
00206   h->addrs = &(h->addr);
00207   h->aliases = NULL;
00208   ret->h_name = (char*)hostname;
00209   ret->h_aliases = &(h->aliases);
00210   ret->h_addrtype = AF_INET;
00211   ret->h_length = sizeof(struct ip_addr);
00212   ret->h_addr_list = (char**)&(h->addrs);
00213 
00214   /* set result != NULL */
00215   *result = ret;
00216 
00217   /* return success */
00218   return 0;
00219 }
00220 
00221 /**
00222  * Frees one or more addrinfo structures returned by getaddrinfo(), along with
00223  * any additional storage associated with those structures. If the ai_next field
00224  * of the structure is not null, the entire list of structures is freed.
00225  *
00226  * @param ai struct addrinfo to free
00227  */
00228 void
00229 lwip_freeaddrinfo(struct addrinfo *ai)
00230 {
00231   struct addrinfo *next;
00232 
00233   while (ai != NULL) {
00234     if (ai->ai_addr != NULL) {
00235       mem_free(ai->ai_addr);
00236     }
00237     if (ai->ai_canonname != NULL) {
00238       mem_free(ai->ai_canonname);
00239     }
00240     next = ai->ai_next;
00241     mem_free(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   struct ip_addr addr;
00271   struct addrinfo *ai;
00272   struct sockaddr_in *sa = NULL;
00273   int port_nr = 0;
00274 
00275   if (res == NULL) {
00276     return EAI_FAIL;
00277   }
00278   *res = NULL;
00279   if ((nodename == NULL) && (servname == NULL)) {
00280     return EAI_NONAME;
00281   }
00282 
00283   if (servname != NULL) {
00284     /* service name specified: convert to port number
00285      * @todo?: currently, only ASCII integers (port numbers) are supported! */
00286     port_nr = atoi(servname);
00287     if ((port_nr <= 0) || (port_nr > 0xffff)) {
00288       return EAI_SERVICE;
00289     }
00290   }
00291 
00292   if (nodename != NULL) {
00293     /* service location specified, try to resolve */
00294     err = netconn_gethostbyname(nodename, &addr);
00295     if (err != ERR_OK) {
00296       return EAI_FAIL;
00297     }
00298   } else {
00299     /* service location specified, use loopback address */
00300     addr.addr = INADDR_LOOPBACK;
00301   }
00302 
00303   ai = mem_malloc(sizeof(struct addrinfo));
00304   if (ai == NULL) {
00305     goto memerr;
00306   }
00307   memset(ai, 0, sizeof(struct addrinfo));
00308   sa = mem_malloc(sizeof(struct sockaddr_in));
00309   if (sa == NULL) {
00310     goto memerr;
00311   }
00312   memset(sa, 0, sizeof(struct sockaddr_in));
00313   /* set up sockaddr */
00314   sa->sin_addr.s_addr = addr.addr;
00315   sa->sin_family = AF_INET;
00316   sa->sin_len = sizeof(struct sockaddr_in);
00317   sa->sin_port = htons(port_nr);
00318 
00319   /* set up addrinfo */
00320   ai->ai_family = AF_INET;
00321   if (hints != NULL) {
00322     /* copy socktype & protocol from hints if specified */
00323     ai->ai_socktype = hints->ai_socktype;
00324     ai->ai_protocol = hints->ai_protocol;
00325   }
00326   if (nodename != NULL) {
00327     /* copy nodename to canonname if specified */
00328     size_t namelen = strlen(nodename);
00329     ai->ai_canonname = mem_malloc(namelen + 1);
00330     if (ai->ai_canonname == NULL) {
00331       goto memerr;
00332     }
00333     MEMCPY(ai->ai_canonname, nodename, namelen);
00334     ai->ai_canonname[namelen] = 0;
00335   }
00336   ai->ai_addrlen = sizeof(struct sockaddr_in);
00337   ai->ai_addr = (struct sockaddr*)sa;
00338 
00339   *res = ai;
00340 
00341   return 0;
00342 memerr:
00343   if (ai != NULL) {
00344     mem_free(ai);
00345   }
00346   if (sa != NULL) {
00347     mem_free(sa);
00348   }
00349   return EAI_MEMORY;
00350 }
00351 
00352 #endif /* LWIP_DNS && LWIP_SOCKET */