gethostent(3n)             DG/UX 4.30              gethostent(3n)



     NAME
          gethostent, gethostbyaddr, gethostbyname, sethostent,
          endhostent - get network host entry

     SYNOPSIS
          #include <netdb.h>

          struct hostent *gethostent()

          struct hostent *gethostbyname(name)
          char *name;

          struct hostent *gethostbyaddr(addr, len, type)
          char *addr; int len, type;

          sethostent(stayopen)
          int stayopen

          endhostent()

     DESCRIPTION
          Gethostent, gethostbyname, and gethostbyaddr each return a
          pointer to an object with the following structure describing
          an Internet host referenced by name or by address,
          respectively.  This structure contains either the
          information obtained from the name server, named(8), YP (see
          Managing NFS and Its Facilities on the DG/UX System), or
          broken-out fields from a line in /etc/hosts.  Gethostbyname
          and gethostbyaddr read the /etc/svcorder file to determine
          which host/name address resolution method to use.  If
          /etc/svcorder does not exist or has invalid data, the
          default order is YP, /etc/hosts, then the name server.

          struct hostent {
             char   *h_name;        /* official name of host */
             char   **h_aliases;    /* alias list */
             int    h_addrtype;     /* host address type */
             int    h_length;       /* length of address */
             char   **h_addr_list;  /* list of address from the name server */
          };
          #define   h_addr h_addr_list[0]  /* address for backward
                                              compatibility */

          The members of this structure are:
          hname
               Official name of the host.

          haliases
               A zero-terminated array of alternate names for the
               host.

          haddrtype



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     gethostent(3n)             DG/UX 4.30              gethostent(3n)



               The type of address being returned; currently always
               AF_INET.

          hlength
               The length, in bytes, of the address.

          haddrlist
               A zero-terminated array of network addresses for the
               host.  Host addresses are returned in network byte
               order.

          haddr
               The first address in haddrlist;  this is for backward
               compatibility.

          When using the name server, gethostbyname will search for
          the named host in the current domain and its parents unless
          the name ends in a dot.  If the name contains no dot, and if
          the environment variable HOSTALIASES contains the name of an
          alias file, the alias file will first be searched for an
          alias matching the input name.  See hostname(7) for the
          domain search procedure and the alias file format.

          Sethostent may be used to request the use of a connected TCP
          socket for queries.  If the stayopen flag is non-zero, this
          sets the option to send all queries to the name server using
          TCP and to retain the connection after each call to
          gethostbyname or gethostbyaddr.  Otherwise, queries are
          performed using UDP datagrams.

          Gethostent reads the next line of /etc/hosts, opening the
          file if necessary.

          Sethostent is redefined to open and rewind the file.  If the
          stayopen argument is non-zero, the hosts database will not
          be closed after each call to gethostbyname or gethostbyaddr.
          Endhostent is redefined to close the file.

          If your system is using the Yellow Pages (YP), you may need
          to see Managing NFS and Its Facilities on the DG/UX System
          for information on how to update the /etc/hosts file.

     DIAGNOSTICS
          Error return status from gethostbyname and gethostbyaddr is
          indicated by return of a null pointer.  The external integer
          herrno may then be checked to see whether this is a
          temporary failure or an invalid or unknown host. The routine
          herror can be used to print an error message describing the
          failure. If its argument string is non-NULL, it is printed,
          followed by a colon and a space.  The error message is
          printed with a trailing newline.




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     gethostent(3n)             DG/UX 4.30              gethostent(3n)



          herrno can have the following values:

          HOST_NOT_FOUND
               No such host is known.

          TRY_AGAIN
               This is usually a temporary error and means that the
               local server did not receive a response from an
               authoritative server.  A retry at some later time may
               succeed.

          NO_RECOVERY
               Some unexpected server failure was encountered.  This
               is a non-recoverable error.

          NO_DATA
               The requested name is valid but does not have an IP
               address; this is not a temporary error.  This means
               that the name is known to the name server but there is
               no address associated with this name. Another type of
               request to the name server using this domain name will
               result in an answer; for example, a mail-forwarder may
               be registered for this domain.

               Null pointer (0) returned on EOF or error.

     FILES
          /etc/hosts, /etc/svcorder

     SEE ALSO
          hosts(4)

     BUGS
          All information is contained in a static area, so you must
          copy it if you want to save it.  Only the Internet address
          format is currently understood.



















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