Tweak ICMP ping check logic for DHCPv4.

Commit f77700aa, which fixes a compiler warning, also breaks the
behaviour of prepending ".<layer>" to basenames in --pxe-service: in
situations where the basename contains a ".", the ".<layer>" suffix is
erroneously added, and in situations where the basename doesn't contain
a ".", the ".<layer>" suffix is erroneously omitted.

A patch against the git HEAD is attached that inverts this logic and
restores the expected behaviour of --pxe-service.

debian/changelog

@@ -1,3 +1,9 @@
+dnsmasq (2.77-2) unstable; urgency=low
+
+   * Improve sed regexp for parsing root.ds.
+
+ -- Simon Kelley <simon@thekelleys.org.uk>  Mon, 5 Jun 2017 20:46:32 +0000
+
 dnsmasq (2.77-1) unstable; urgency=low
 
    * New upstream.

debian/init

@@ -111,7 +111,7 @@ DNSMASQ_OPTS="$DNSMASQ_OPTS --local-service"
 ROOT_DS="/usr/share/dns/root.ds"
 
 if [ -f $ROOT_DS ]; then
-   DNSMASQ_OPTS="$DNSMASQ_OPTS `sed -e s/"^.*DS[\t ]"/--trust-anchor=.,/ -e s/" "/,/g $ROOT_DS | tr '\n' ' '`" 
+    DNSMASQ_OPTS="$DNSMASQ_OPTS `sed -rne "s/^([.a-ZA-Z0-9]+)([[:space:]]+[0-9]+)*([[:space:]]+IN)*[[:space:]]+DS[[:space:]]+/--trust-anchor=\1,/;s/[[:space:]]+/,/gp" $ROOT_DS | tr '\n' ' '`"
 fi
 
 start()

src/rfc2131.c

@@ -836,10 +836,10 @@ size_t dhcp_reply(struct dhcp_context *context, char *iface_name, int int_index,
 	  
 	  if (strchr(service->basename, '.'))
 	    snprintf((char *)mess->file, sizeof(mess->file),
-		"%s.%d", service->basename, layer);
+		"%s", service->basename);
 	  else
 	    snprintf((char *)mess->file, sizeof(mess->file),
-		"%s", service->basename);
+		"%s.%d", service->basename, layer);
 	  
 	  option_put(mess, end, OPTION_MESSAGE_TYPE, 1, DHCPACK);
 	  option_put(mess, end, OPTION_SERVER_IDENTIFIER, INADDRSZ, htonl(context->local.s_addr));
@@ -1040,7 +1040,7 @@ size_t dhcp_reply(struct dhcp_context *context, char *iface_name, int int_index,
 		  else if (have_config(config, CONFIG_DECLINED) &&
 			   difftime(now, config->decline_time) < (float)DECLINE_BACKOFF)
 		    my_syslog(MS_DHCP | LOG_WARNING, _("not using configured address %s because it was previously declined"), addrs);
-		  else if (!do_icmp_ping(now, config->addr, 0, loopback))
+		  else if ((!lease || lease->addr.s_addr != config->addr.s_addr) && !do_icmp_ping(now, config->addr, 0, loopback))
 		    my_syslog(MS_DHCP | LOG_WARNING, _("not using configured address %s because it is in use by another host"), addrs);
 		  else
 		    conf = config->addr;