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masock_sa2name.c

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/** \file masock_sa2name.c
 *  (C) Copyright 2001 by Matthias Andree
 *  \author Matthias Andree
 *  \year 2001
 */

#include "masock.h"
#include "critmem.h"
#include "config.h"

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#ifndef __LCLINT__
#include <arpa/inet.h>
#endif /* not __LCLINT__ */
#include <netdb.h>

#include <string.h>

#ifdef WITH_DMALLOC
#include <dmalloc.h>
#endif

#include <errno.h>

/** Look up the host name belonging to the socket address. If compiled
 * with IPv6 support, use IPv6 lookup unless the address is actually an
 * IPv6-mapped IPv4 address.
 *
 * \return strdup'ed string containing the host name or NULL in case of
 * trouble.
 *
 * \bug Linux glibc has broken IN6_IS_ADDR_* macros that do not cast to
 * const.
 * 
 */
char *
00039 masock_sa2name(const struct sockaddr *sa
    /** socket address to convert */ ,
             /*@out@*/ int *h_e
    /** variable to place h_errno into */ )
{
    struct hostent *he;
    char *ret;

    switch (sa->sa_family) {
#ifdef HAVE_IPV6
    case AF_INET6:
      /* any warnings issued here are the fault of broken system
         includes */
      if (IN6_IS_ADDR_V4MAPPED(&((const struct sockaddr_in6 *)sa)->sin6_addr)) {
          /* do IPv4 lookup on mapped addresses */
          /* see RFC-2553 section 6.2 for "12" */
          he = gethostbyaddr(12 + (const char *)
                         &((const struct sockaddr_in6 *)sa)
                         ->sin6_addr, sizeof(struct in_addr), AF_INET);
      } else {
          /* real IPv6 */
          he = gethostbyaddr((const char *)
                         &((const struct sockaddr_in6 *)sa)
                         ->sin6_addr,
                         sizeof(struct in6_addr), sa->sa_family);
      }
      if (!he)
          errno = 0, *h_e = h_errno;
      break;
#endif
    case AF_INET:
      he = gethostbyaddr((const char *)
                     &((const struct sockaddr_in *)sa)
                     ->sin_addr.s_addr,
                     sizeof(struct in_addr), sa->sa_family);
      if (!he)
          errno = 0, *h_e = h_errno;
      break;
    default:
      errno = EAFNOSUPPORT;
      *h_e = 0;
      he = 0;
      break;
    }

    ret = he && he->h_name ? critstrdup(he->h_name, "masock_sa2name") : 0;
    endhostent();
    return ret;
}

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