GETSERVENT(3N)                                                  GETSERVENT(3N)


NAME
     getservent, getservent_r, fgetservent, fgetservent_r, getservbyport,
     getservbyport_r, getservbyname, getservbyname_r, setservent, endservent -
     get service entry

SYNOPSIS
     #include <netdb.h>

     struct servent *getservent(void);

     struct servent *getservent_r(struct servent *entry, char *buffer, int bufsize);

     struct servent *fgetservent(FILE *);

     struct servent *fgetservent_r(FILE *, struct servent *entry, char *buffer, int bufsize);

     struct servent *getservbyname(const char *name, const char *proto);

     struct servent *getservbyname_r(const char *name, const char *proto, struct servent *entry, char *buffer, int bufsize);

     struct servent *getservbyport(int port, const char *proto);

     struct servent *getservbyport_r(int port, const char *proto, struct servent *entry, char *buffer, int bufsize);

     void setservent(int stayopen);

     void endservent(void);

DESCRIPTION
     getservent, getservbyname, getservbyport and their reentrant counterparts
     each return a pointer to an object with the following structure
     containing the broken-out fields of a line in the file /etc/services, or
     some other back-end database.

          struct    servent {
               char *s_name;  /* official name of service */
               char **s_aliases;   /* alias list */
               int  s_port;        /* port service resides at */
               char *s_proto; /* protocol to use */
          };

     The members of this structure are:

     s_name     The official name of the service.

     s_aliases  A zero terminated list of alternate names for the service.

     s_port     The port number at which the service  resides.   Port  numbers
                are returned as a 16-bit value in network byte order.


     s_proto    The name of the protocol to use when contacting the service.

     Getservent reads  the  next  line  of  the  file,  opening  the  file  if
     necessary.

     Setservent opens and rewinds the file.  If the stayopen flag is non-zero,
     the  net data base will not be closed after each call to getservbyname or
     getservbyport.

     Endservent closes the file.

     Getservbyname and getservbyport sequentially search from the beginning of
     the file until a matching protocol name or port number is found, or until
     EOF is encountered.  If a protocol  name  is  also  supplied  (non-NULL),
     searches must also match the protocol.

     The routines fgetservent and fgetservent_r return the next entry from the
     supplied stream as a struct servent structure.  The stream must be of the
     same format as the file /etc/services.

     The functions getservent, fgetservent,  getservbyname  and  getservbyport
     all  return  results in static memory which are overwritten on each call.
     Reentrant versions of each of these routines getservent_r, fgetservent_t,
     getservbyname_r  and  getservbyport_r  are  provided to parse the results
     into supplied memory.  They take three extra arguments, a  pointer  to  a
     struct  servent  structure, a pointer to a character buffer, and a length
     for the buffer.

     The functions presented in this manual  page  only  parse  files  of  the
     format  given  in  services(4).   Other back-end databases and protocols,
     such as NIS, can be supplied by the nsd(1M) daemon as  specified  in  the
     nsd configuration file /etc/nsswitch.conf.

NOTE
     The Mips ABI specifies nothing but local files so applications which wish
     to use anything else must compile with libc prior to libnsl in the
     library list.

     When nsd is running changes in the local services file may not be noticed
     by getservent() until the enumeration cache file has timed out.

DIAGNOSTICS
     All functions that return struct servent * will return a null (0) pointer
     in the case of EOF or failure.

FILES
     /etc/services /etc/nsswitch.conf /var/ns/cache/services.byname.m
     /var/ns/cache/services.byport.m


SEE ALSO
     nsd(1M), getprotoent(3N), services(4)

DIAGNOSTICS
     Null pointer (0) returned on EOF or error.

BUGS
     Expecting port numbers to fit in a 32-bit quantity is probably naive.


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