text: /**
   * @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"
  
  /** 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        == 0x%08lX\n",(u32_t)(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]->   == 0x%08lX\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       == %lu\n",    (u32_t)(s_hostent.h_addrtype)));
    LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_length         == %lu\n",    (u32_t)(s_hostent.h_length)));
    LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_addr_list      == 0x%08lX\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]   == 0x%08lX\n", idx, s_hostent.h_addr_list[idx]));
        LWIP_DEBUGF(DNS_DEBUG, ("hostent.h_addr_list[%i]-> == %s\n",      idx, inet_ntoa(*((struct in_addr*)(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) {
      if (ai->ai_addr != NULL) {
        mem_free(ai->ai_addr);
      }
      if (ai->ai_canonname != NULL) {
        mem_free(ai->ai_canonname);
      }
      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;
  
    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 = INADDR_LOOPBACK;
    }
  
    ai = mem_malloc(sizeof(struct addrinfo));
    if (ai == NULL) {
      goto memerr;
    }
    memset(ai, 0, sizeof(struct addrinfo));
    sa = mem_malloc(sizeof(struct sockaddr_in));
    if (sa == NULL) {
      goto memerr;
    }
    memset(sa, 0, sizeof(struct sockaddr_in));
    /* 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 */
      size_t namelen = strlen(nodename);
      ai->ai_canonname = mem_malloc(namelen + 1);
      if (ai->ai_canonname == NULL) {
        goto memerr;
      }
      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);
    }
    if (sa != NULL) {
      mem_free(sa);
    }
    return EAI_MEMORY;
  }
  
  #endif /* LWIP_DNS && LWIP_SOCKET */
  