Add support for external tarballs

Signed-off-by: Jan Engelhardt <jengelh@computergmbh.de>

.gitignore

@@ -12,6 +12,8 @@ Makefile
 Makefile.in
 Module.symvers
 
+/downloads
+
 /aclocal.m4
 /autom4te*.cache
 /compile

README

@@ -8,3 +8,32 @@ package.
 Xtables-addons is different from patch-o-matic in that you do not have
 to patch or recompile either kernel or Xtables(iptables). But please
 see the INSTALL file for the minimum requirements of this package.
+
+
+External extensions
+===================
+
+The program "xa-download-more" can be used to download more extensions
+from 3rd parties into the source tree. The URLs are listed in the
+"sources" file. If the "sources" file contains an entry like
+
+	http://foobar.org/xa/
+
+xa-download-more will inspect http://foobar.org/xa/xa-index.txt for files
+to download. That file may contain
+
+	foobar.tar.bz2
+
+and xa-download-more will then retrieve and unpack
+http://foobar.org/xa/foobar.tar.bz2.
+
+Files that should be contained in the tarball are an mconfig and Kbuild
+files to control building the extension, libxt_foobar.c for the userspace
+extension and xt_foobar.c for the kernel extension.
+
+	mconfig.foobar
+	extensions/Kbuild.foobar
+	extensions/libxt_foobar.c
+	extensions/libxt_foobar.man
+	extensions/xt_foobar.c
+	extensions/xt_foobar.h

sources

@@ -0,0 +1,3 @@
+#
+# Source URLs for external patchlets
+#

xa-download-more

@@ -0,0 +1,83 @@
+#!/usr/bin/perl -w
+
+use HTTP::Request;
+use LWP::UserAgent;
+use strict;
+
+&main(\@ARGV);
+
+sub main ($)
+{
+	local *FH;
+
+	if (!-d "downloads") {
+		if (!mkdir("downloads")) {
+			die "Could not create downloads/ directory";
+		}
+	}
+
+	open(FH, "<sources");
+	while (defined($_ = <FH>)) {
+		chomp $_;
+		$_ =~ s/#.*//gs;
+		$_ =~ s/^\s+|\s+$//gs;
+		if (length($_) == 0) {
+			next;
+		}
+		&process_index($_);
+	}
+
+	close FH;
+}
+
+sub process_index ($)
+{
+	my $top = shift @_;
+	my($agent, $res, $url);
+	local *FH;
+
+	$agent = LWP::UserAgent->new();
+	$agent->env_proxy();
+
+	$url = &slash_remove("$top/xa-index.txt");
+	print "  GET     $url\n";
+	$res = $agent->get($url);
+	if (!$res->is_success()) {
+		print STDERR "  `->     ", $res->status_line(), "\n";
+		return;
+	}
+
+	foreach my $ext (split(/\s+/, $res->content())) {
+		my($ex_url, $ex_res);
+
+		$ex_url = &slash_remove("$top/$ext");
+		print "  GET     $ex_url\n";
+
+		$ex_res = $agent->mirror($ex_url, "downloads/$ext");
+		if ($ex_res->code() == 304) {
+			# "Not modified" = up to date
+			next;
+		}
+		if (!$ex_res->is_success()) {
+			print STDERR "  `->     ", $ex_res->status_line(), "\n";
+			next;
+		}
+
+		print "  UNPACK  downloads/$ext\n";
+		system "tar", "-xjf", "downloads/$ext";
+	}
+}
+
+sub slash_remove ($)
+{
+	my $s = shift @_;
+	$s =~ s{(\w+://)(.*)}{$1.&slash_remove2($2)}eg;
+	return $s;
+}
+
+sub slash_remove2 ($)
+{
+	my $s = shift @_;
+	$s =~ s{/+}{/}g;
+	return $s;
+}