netcfg does not set netcfg/dhcp_ntp_servers

[Simon Kuhn]

netcfg in precise no longer has logic to set netcfg/dhcp_ntp_servers in debconf. This causes clock-setup to fail to run rdate against the first provided NTP server to set the time during install (which can lead to other problems). This is a regression from lucid's behavior which correctly passed DHCP-provided NTP servers into clock-setup.

netcfg-1.51ubuntu3 in lucid has the following logic in dhcp.c:

                /*
                 * Record any ntp server information from DHCP for later
                 * verification and use by clock-setup
                 */
                if ((d = fopen(NTP_SERVER_FILE, "r")) != NULL) {
                    char ntpservers[DHCP_OPTION_LEN + 1] = { 0 };
                    fgets(ntpservers, DHCP_OPTION_LEN, d);
                    fclose(d);
                    unlink(NTP_SERVER_FILE);

                    if (!empty_str(ntpservers)) {
                        debconf_set(client, "netcfg/dhcp_ntp_servers",
                                    ntpservers);
                    }
                }

netcfg-1.68ubuntu14 in precise has the following, which never calls debconf_set:

    /*
     * Record any ntp server information from DHCP for later
     * verification and use by clock-setup
     */
    if ((d = fopen(NTP_SERVER_FILE, "r")) != NULL) {
        char ntpservers[DHCP_OPTION_LEN + 1] = { 0 }, *ptr, *srv;
        int i;

        di_debug("Reading NTP servers from DHCP info");

        if (fgets(ntpservers, DHCP_OPTION_LEN, d) == NULL) {
            /* ignore errors; we check for empty strings later */
        }
        rtrim(ntpservers);
        fclose(d);
        unlink(NTP_SERVER_FILE);

        if (!empty_str(ntpservers)) {
            ptr = ntpservers;
            for (i = 0; i < NETCFG_NTPSERVERS_MAX; i++) {
                srv = strtok_r(ptr, " \n\t", &ptr);
                if (srv) {
                    di_debug("Read NTP server %s", srv);
                    strncpy(interface->ntp_servers[i], srv, NETCFG_ADDRSTRLEN);
                } else {
                    *(interface->ntp_servers[i]) = '\0';
                }
            }
        }
    }