Linux IPv6 interface discovery patch dhcp4

[Matthew Newton]

Hi,

I'm new here - hope this is the correct place for patches :)

In playing with dhcpd 4.1.0a2 (and 4.0.0) there is a bug whereby
it refuses to start up if /proc/net/if_inet6 does not exist. This
is the case on machines that do not have IPv6 support.

In this case, even if "-4" is specified on the dhcpd command line,
the following error is given, and the daemon refuses to start:

Error opening '/proc/net/if_inet6' to list IPv6 interfaces; No such file or directory

The following patch fixes that by not scanning /proc/net/if_inet6
if the daemon has been started in IPv4 mode. It's also available as
original file at
http://www.le.ac.uk/its/mcn4/dhcpd/linux_ipv6_discover.patch

I thought about compiling with --disable-dhcpv6, but that produces
compile-time errors on 4.0 ;)

Cheers,

Matthew


diff -Naur dhcp-4.1.0a2/common/discover.c dhcp-4.1.0a2-mcn/common/discover.c
--- dhcp-4.1.0a2/common/discover.c	2008-08-29 18:48:57.000000000 +0100
+++ dhcp-4.1.0a2-mcn/common/discover.c	2008-10-02 13:02:06.000000000 +0100
@@ -443,15 +443,17 @@
 	}
 
 #ifdef DHCPv6
-	ifaces->fp6 = fopen("/proc/net/if_inet6", "r");
-	if (ifaces->fp6 == NULL) {
-		log_error("Error opening '/proc/net/if_inet6' to "
-			  "list IPv6 interfaces; %m");
-		close(ifaces->sock);
-		ifaces->sock = -1;
-		fclose(ifaces->fp);
-		ifaces->fp = NULL;
-		return 0;
+	if (local_family == AF_INET6) {
+		ifaces->fp6 = fopen("/proc/net/if_inet6", "r");
+		if (ifaces->fp6 == NULL) {
+			log_error("Error opening '/proc/net/if_inet6' to "
+				  "list IPv6 interfaces; %m");
+			close(ifaces->sock);
+			ifaces->sock = -1;
+			fclose(ifaces->fp);
+			ifaces->fp = NULL;
+			return 0;
+		}
 	}
 #endif
 
@@ -720,7 +722,8 @@
 	}
 #ifdef DHCPv6
 	if (!(*err)) {
-		return next_iface6(info, err, ifaces);
+		if (local_family == AF_INET6)
+			return next_iface6(info, err, ifaces);
 	}
 #endif
 	return 0;
@@ -736,7 +739,8 @@
 	close(ifaces->sock);
 	ifaces->sock = -1;
 #ifdef DHCPv6
-	fclose(ifaces->fp6);
+	if (local_family == AF_INET6)
+		fclose(ifaces->fp6);
 	ifaces->fp6 = NULL;
 #endif
 }


-- 
Matthew Newton, Ph.D. <mcn4 at le.ac.uk>

Systems Architect (UNIX and Networks), Network Services,
I.T. Services, University of Leicester, Leicester LE1 7RH, United Kingdom

For IT help contact helpdesk extn. 2253, <ithelp at le.ac.uk>