Enable host-to-IP resolving in parse_host_mac_ip_list().

This adds functionality to the parse_host_mac_ip_list() function
making it able to resolve hostnames into numeric IP addresses.
Users can now have lines looking like

	www	01:23:45:67:89:ab	www.example.com

and the "www.example.com" name will be resolved into IP address(es)
that are added to the 'ipv4' and 'ipv6' elements as appropriate.

This is however not the default behaviour.  To enable it, users
must specify the flag 'resolve' in the new (optional) ``flags''
parameter to the function.

lib/puppet/parser/functions/parse_host_mac_ip_list.rb

@@ -12,11 +12,23 @@ module Puppet::Parser::Functions
 
 	This function parses lines containing hostname, MAC address, and IP
 	address(es), returning a hash mapping from hostname to a records
-	(in the form of hashes) with the MAC and IP addresses.	The single
-	parameter is a string, or (nested) list of strings, containing
-	lines.	Each line should be on the format
+	(in the form of hashes) with the MAC and IP addresses.  It takes two
+	parameters:
 
-	    NAME	MACADDR		[IPADDR ...]
+	 * hostlist_lines  (mandatory)
+		String or (nested) list of strings containing lines of hosts
+		with MAC and IP addresses.  See below for more details.
+
+	 * flags  (optional)
+		Flags altering the behaviour of the function.  Flags can be
+		given as comma-separated names in a string, or as a (nested)
+		list of such flag string.
+		The following flags are recognized:
+		 - resolve	Resolve names in the IP address section.
+
+	The lines in the hostlist_lines parameter must be on the format
+
+		NAME	MACADDR		[IPADDR ...]
 
 	i.e, a name, a MAC address, and zero, one or more IP addresses, all
 	separated by horizontal whitespace.
@@ -32,6 +44,12 @@ module Puppet::Parser::Functions
 	returned with the brackets removed.  Numeric IP addresses will be
 	canonicalized.
 
+	If the "resolve" flag is specified, hostnames without square brackets
+	around them can also be listed.  Such names will be resolved into
+	numeric IP addresses, and those will be added to the "ipv4" and
+	"ipv6" elements as appropriate; the name itself will not be added to
+	the "ip_Name" element.
+
 	The return value is a hash with the host names as keys, and the
 	value for each host being a hash with the following items:
 	 - "mac"	The MAC addresses (if any) for the host
@@ -95,13 +113,35 @@ module Puppet::Parser::Functions
 		},
 	    }
 
+	If the "resolve" flag is specified, then the line
+
+	    web		-		www.example.com [dub-dub-dub]
+
+	will be parsed into the element
+
+		"web" => {
+			"mac"     => [ ],
+			"ipv4"    => [ "192.0.2.80" ],
+			"ipv6"    => [ "2001:db8:1::80", "2001:db8:1::443" ],
+			"ip_Name" => [ "dub-dub-dub" ],
+			"ip"      => [ "192.0.2.80", "2001:db8:1::80", "2001:db8:1::443", "dub-dub-dub" ],
+		},
+
+	(assuming some specific entries in DNS for www.example.com).
+
     ') \
     do |args|
-	if args.length != 1
+	if args.length < 1 or args.length > 2
 	    raise(Puppet::ParseError,
 		  "parse_host_mac_ip_list(): Wrong number of arguments")
 	end
 	hostlist_lines = [args[0]].flatten.join("\n").split("\n")
+	flags = [(args[1] or [])].flatten.join(",").split(",")
+	do_resolve = flags.delete('resolve')
+	if not flags.empty?
+	    raise(Puppet::ParseError,
+		  "parse_host_mac_ip_list(): Bad flag ``#{flags[0]}''")
+	end
 
 	# Skip blank lines and comments
 	hostlist_lines = hostlist_lines.select { |line|
@@ -141,13 +181,32 @@ module Puppet::Parser::Functions
 		begin
 		    ipa = IPAddr.new(ip)
 		rescue ArgumentError => err
-		    errmsg = "parse_host_mac_ip_list(): #{err.to_s}, `#{ip}'"
-		    raise(err.class.new(errmsg))
+		    if not do_resolve
+			errmsg = "parse_host_mac_ip_list(): #{err.to_s}, `#{ip}'"
+			raise(err.class.new(errmsg))
+		    else
+			# Ignore, and continue to see if it can be resolved
+		    end
 		else
 		    ipaddrs[ipa.family] << ipa.to_s
 		    next
 		end
 
+		if do_resolve
+		    begin
+			addrinfos = Socket.getaddrinfo( # No reverse lookups
+			    ip, nil, nil, nil, nil, 0, false)
+		    rescue SocketError => err
+			errmsg = "parse_host_mac_ip_list(): #{err.to_s}, `#{ip}'"
+			raise(err.class.new(errmsg))
+		    else
+			addrinfos.each do |ai|
+			    ipaddrs[ai[4]] << ai[3]
+			end
+			next
+		    end
+		end
+
 		# Catch-all
 		raise(Puppet::ParseError,
 		      "parse_host_mac_ip_list(): Invalid IP format, `#{ip}'")