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/**

 * @file

 * API functions for name resolving

 *

 */

/*

 * Redistribution and use in source and binary forms, with or without modification,

 * are permitted provided that the following conditions are met:

 *

 * 1. Redistributions of source code must retain the above copyright notice,

 *    this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright notice,

 *    this list of conditions and the following disclaimer in the documentation

 *    and/or other materials provided with the distribution.

 * 3. The name of the author may not be used to endorse or promote products

 *    derived from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED

 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF

 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT

 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,

 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT

 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING

 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY

 * OF SUCH DAMAGE.

 *

 * This file is part of the lwIP TCP/IP stack.

 *

 * Author: Simon Goldschmidt

 *

 */

#include "lwip/netdb.h"

#if LWIP_DNS && LWIP_SOCKET

#include "lwip/err.h"

#include "lwip/mem.h"

#include "lwip/ip_addr.h"

#include "lwip/api.h"

#include <string.h>

#include <stdlib.h>

/** helper struct for gethostbyname_r to access the char* buffer */

struct gethostbyname_r_helper {

  struct ip_addr *addrs;

  struct ip_addr addr;

  char *aliases;

};

/** h_errno is exported in netdb.h for access by applications. */

#if LWIP_DNS_API_DECLARE_H_ERRNO

int h_errno;

#endif /* LWIP_DNS_API_DECLARE_H_ERRNO */

/** define "hostent" variables storage: 0 if we use a static (but unprotected)

 * set of variables for lwip_gethostbyname, 1 if we use a local storage */

#ifndef LWIP_DNS_API_HOSTENT_STORAGE

#define LWIP_DNS_API_HOSTENT_STORAGE 0

#endif

/** define "hostent" variables storage */

#if LWIP_DNS_API_HOSTENT_STORAGE

#define HOSTENT_STORAGE

#else

#define HOSTENT_STORAGE static

#endif /* LWIP_DNS_API_STATIC_HOSTENT */

/**

 * Returns an entry containing addresses of address family AF_INET

 * for the host with name name.

 * Due to dns_gethostbyname limitations, only one address is returned.

 *

 * @param name the hostname to resolve

 * @return an entry containing addresses of address family AF_INET

 *         for the host with name name

 */

struct hostent*

lwip_gethostbyname(const char *name)

{

  err_t err;

  struct ip_addr addr;

  /* buffer variables for lwip_gethostbyname() */

  HOSTENT_STORAGE struct hostent s_hostent;

  HOSTENT_STORAGE char *s_aliases;

  HOSTENT_STORAGE struct ip_addr s_hostent_addr;

  HOSTENT_STORAGE struct ip_addr *s_phostent_addr;

  /* query host IP address */

  err = netconn_gethostbyname(name, &addr);

  if (err != ERR_OK) {

    LWIP_DEBUGF(DNS_DEBUG, ("lwip_gethostbyname(%s) failed, err=%d\n", name, err));

    h_errno = HOST_NOT_FOUND;

    return NULL;

  }

  /* fill hostent */

  s_hostent_addr = addr;

  s_phostent_addr = &s_hostent_addr;

  s_hostent.h_name = (char*)name;

  s_hostent.h_aliases = &s_aliases;

  s_hostent.h_addrtype = AF_INET;

  s_hostent.h_length = sizeof(struct ip_addr);

  s_hostent.h_addr_list = (char**)&s_phostent_addr;

#if DNS_DEBUG

  /* dump hostent */

  LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_name           == %s\n", s_hostent.h_name));

  LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_aliases        == %p\n", s_hostent.h_aliases));

  if (s_hostent.h_aliases != NULL) {

    u8_t idx;

    for ( idx=0; s_hostent.h_aliases[idx]; idx++) {

      LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_aliases[%i]->   == %p\n", idx, s_hostent.h_aliases[idx]));

      LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_aliases[%i]->   == %s\n", idx, s_hostent.h_aliases[idx]));

    }

  }

  LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_addrtype       == %d\n", s_hostent.h_addrtype));

  LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_length         == %d\n", s_hostent.h_length));

  LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_addr_list      == %p\n", s_hostent.h_addr_list));

  if (s_hostent.h_addr_list != NULL) {

    u8_t idx;

    for ( idx=0; s_hostent.h_addr_list[idx]; idx++) {

      LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_addr_list[%i]   == %p\n", idx, s_hostent.h_addr_list[idx]));

      LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_addr_list[%i]-> == %s\n", idx, ip_ntoa(s_hostent.h_addr_list[idx])));

    }

  }

#endif /* DNS_DEBUG */

#if LWIP_DNS_API_HOSTENT_STORAGE

  /* this function should return the "per-thread" hostent after copy from s_hostent */

  return sys_thread_hostent(&s_hostent);

#else

  return &s_hostent;

#endif /* LWIP_DNS_API_HOSTENT_STORAGE */

}

/**

 * Thread-safe variant of lwip_gethostbyname: instead of using a static

 * buffer, this function takes buffer and errno pointers as arguments

 * and uses these for the result.

 *

 * @param name the hostname to resolve

 * @param ret pre-allocated struct where to store the result

 * @param buf pre-allocated buffer where to store additional data

 * @param buflen the size of buf

 * @param result pointer to a hostent pointer that is set to ret on success

 *               and set to zero on error

 * @param h_errnop pointer to an int where to store errors (instead of modifying

 *                 the global h_errno)

 * @return 0 on success, non-zero on error, additional error information

 *         is stored in *h_errnop instead of h_errno to be thread-safe

 */

int

lwip_gethostbyname_r(const char *name, struct hostent *ret, char *buf,

                size_t buflen, struct hostent **result, int *h_errnop)

{

  err_t err;

  struct gethostbyname_r_helper *h;

  char *hostname;

  size_t namelen;

  int lh_errno;

  if (h_errnop == NULL) {

    /* ensure h_errnop is never NULL */

    h_errnop = &lh_errno;

  }

  if (result == NULL) {

    /* not all arguments given */

    *h_errnop = EINVAL;

    return -1;

  }

  /* first thing to do: set *result to nothing */

  *result = NULL;

  if ((name == NULL) || (ret == NULL) || (buf == 0)) {

    /* not all arguments given */

    *h_errnop = EINVAL;

    return -1;

  }

  namelen = strlen(name);

  if (buflen < (sizeof(struct gethostbyname_r_helper) + namelen + 1 + (MEM_ALIGNMENT - 1))) {

    /* buf can't hold the data needed + a copy of name */

    *h_errnop = ERANGE;

    return -1;

  }

  h = (struct gethostbyname_r_helper*)LWIP_MEM_ALIGN(buf);

  hostname = ((char*)h) + sizeof(struct gethostbyname_r_helper);

  /* query host IP address */

  err = netconn_gethostbyname(name, &(h->addr));

  if (err != ERR_OK) {

    LWIP_DEBUGF(DNS_DEBUG, ("lwip_gethostbyname(%s) failed, err=%d\n", name, err));

    *h_errnop = ENSRNOTFOUND;

    return -1;

  }

  /* copy the hostname into buf */

  MEMCPY(hostname, name, namelen);

  hostname[namelen] = 0;

  /* fill hostent */

  h->addrs = &(h->addr);

  h->aliases = NULL;

  ret->h_name = (char*)hostname;

  ret->h_aliases = &(h->aliases);

  ret->h_addrtype = AF_INET;

  ret->h_length = sizeof(struct ip_addr);

  ret->h_addr_list = (char**)&(h->addrs);

  /* set result != NULL */

  *result = ret;

  /* return success */

  return 0;

}

/**

 * Frees one or more addrinfo structures returned by getaddrinfo(), along with

 * any additional storage associated with those structures. If the ai_next field

 * of the structure is not null, the entire list of structures is freed.

 *

 * @param ai struct addrinfo to free

 */

void

lwip_freeaddrinfo(struct addrinfo *ai)

{

  struct addrinfo *next;

  while (ai != NULL) {

    next = ai->ai_next;

    mem_free(ai);

    ai = next;

  }

}

/**

 * Translates the name of a service location (for example, a host name) and/or

 * a service name and returns a set of socket addresses and associated

 * information to be used in creating a socket with which to address the

 * specified service.

 * Memory for the result is allocated internally and must be freed by calling

 * lwip_freeaddrinfo()!

 *

 * Due to a limitation in dns_gethostbyname, only the first address of a

 * host is returned.

 * Also, service names are not supported (only port numbers)!

 *

 * @param nodename descriptive name or address string of the host

 *                 (may be NULL -> local address)

 * @param servname port number as string of NULL

 * @param hints structure containing input values that set socktype and protocol

 * @param res pointer to a pointer where to store the result (set to NULL on failure)

 * @return 0 on success, non-zero on failure

 */

int

lwip_getaddrinfo(const char *nodename, const char *servname,

       const struct addrinfo *hints, struct addrinfo **res)

{

  err_t err;

  struct ip_addr addr;

  struct addrinfo *ai;

  struct sockaddr_in *sa = NULL;

  int port_nr = 0;

  size_t total_size;

  size_t namelen = 0;

  if (res == NULL) {

    return EAI_FAIL;

  }

  *res = NULL;

  if ((nodename == NULL) && (servname == NULL)) {

    return EAI_NONAME;

  }

  if (servname != NULL) {

    /* service name specified: convert to port number

     * @todo?: currently, only ASCII integers (port numbers) are supported! */

    port_nr = atoi(servname);

    if ((port_nr <= 0) || (port_nr > 0xffff)) {

      return EAI_SERVICE;

    }

  }

  if (nodename != NULL) {

    /* service location specified, try to resolve */

    err = netconn_gethostbyname(nodename, &addr);

    if (err != ERR_OK) {

      return EAI_FAIL;

    }

  } else {

    /* service location specified, use loopback address */

    addr.addr = htonl(INADDR_LOOPBACK);

  }

  total_size = sizeof(struct addrinfo) + sizeof(struct sockaddr_in);

  if (nodename != NULL) {

    namelen = strlen(nodename);

    LWIP_ASSERT("namelen is too long", (namelen + 1) <= (mem_size_t)-1);

    total_size += namelen + 1;

  }

  ai = mem_malloc(total_size);

  if (ai == NULL) {

    goto memerr;

  }

  memset(ai, 0, total_size);

  sa = (struct sockaddr_in*)((u8_t*)ai + sizeof(struct addrinfo));

  /* set up sockaddr */

  sa->sin_addr.s_addr = addr.addr;

  sa->sin_family = AF_INET;

  sa->sin_len = sizeof(struct sockaddr_in);

  sa->sin_port = htons(port_nr);

  /* set up addrinfo */

  ai->ai_family = AF_INET;

  if (hints != NULL) {

    /* copy socktype & protocol from hints if specified */

    ai->ai_socktype = hints->ai_socktype;

    ai->ai_protocol = hints->ai_protocol;

  }

  if (nodename != NULL) {

    /* copy nodename to canonname if specified */

    ai->ai_canonname = ((char*)ai + sizeof(struct addrinfo) + sizeof(struct sockaddr_in));

    MEMCPY(ai->ai_canonname, nodename, namelen);

    ai->ai_canonname[namelen] = 0;

  }

  ai->ai_addrlen = sizeof(struct sockaddr_in);

  ai->ai_addr = (struct sockaddr*)sa;

  *res = ai;

  return 0;

memerr:

  if (ai != NULL) {

    mem_free(ai);

  }

  return EAI_MEMORY;

}

#endif /* LWIP_DNS && LWIP_SOCKET */