Do

# man setrpcent

I got
...
       getrpcent() reads the next line of the file,  opening  the
       file if necessary.

       getrpcent()  opens  and rewinds the file.  If the stayopen
       flag is non-zero, the net data base  will  not  be  closed
       after  each call to getrpcent() (either directly, or indi-
       rectly through one of the other "getrpc" calls).

I think the second getrpcent should be setrpcent.