def read_resolv_conf(self, f):
        if isinstance(f, str) or isinstance(f, unicode):
            try:
                f = open(f, 'r')
            except IOError:
                # /etc/resolv.conf doesn't exist, can't be read, etc.
                # We'll just use the default resolver configuration.
                self.nameservers = ['127.0.0.1']
                return
            want_close = True
        else:
            want_close = False
        try:
            for l in f:
                if len(l) == 0 or l[0] == '#' or l[0] == ';':
                    continue
                tokens = l.split()
                if len(tokens) == 0:
                    continue
                if tokens[0] == 'nameserver':
                    self.nameservers.append(tokens[1])
                elif tokens[0] == 'domain':
                    self.domain = dns.name.from_text(tokens[1])
                elif tokens[0] == 'search':
                    for suffix in tokens[1:]:
                        self.search.append(dns.name.from_text(suffix))
        finally:
            if want_close:
                f.close()
        if len(self.nameservers) == 0:
            self.nameservers.append('127.0.0.1')
Process f as a file in the /etc/resolv.conf format.  If f is
dataset/ETHPy150Open catap/namebench/nb_third_party/dns/resolver.py/Resolver.read_resolv_conf