From 603d5f21ab8c580422b06bc776a5b8c514d663a7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Petr=20=C5=A0tetiar?= <ynezz@true.cz>
Date: Thu, 19 Nov 2020 16:32:46 +0100
Subject: [PATCH] download: handle possibly invalid local tarballs
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Currently it's assumed, that already downloaded tarballs are always
fine, so no checksum checking is performed and the tarball is used even
if it might be corrupted.

From now on, we're going to always check the downloaded tarballs before
considering them valid.

Steps to reproduce:

 1. Remove cached tarball

   rm dl/libubox-2020-08-06-9e52171d.tar.xz

 2. Download valid tarball again

   make package/libubox/download

 3. Invalidate the tarball

   sed -i 's/PKG_MIRROR_HASH:=../PKG_MIRROR_HASH:=ff/' package/libs/libubox/Makefile

 4. Now compile with corrupt tarball source

   make package/libubox/{clean,compile}

Signed-off-by: Petr Štetiar <ynezz@true.cz>
---
 include/host-build.mk |  2 ++
 include/package.mk    |  2 ++
 scripts/download.pl   | 18 ++++++++++++++++++
 3 files changed, 22 insertions(+)

diff --git a/include/host-build.mk b/include/host-build.mk
index 9fc14241c6..1cd9ff5ac0 100644
--- a/include/host-build.mk
+++ b/include/host-build.mk
@@ -184,6 +184,8 @@ ifndef DUMP
     clean-build: host-clean-build
   endif
 
+  $(DL_DIR)/$(FILE): FORCE
+
   $(_host_target)host-prepare: $(HOST_STAMP_PREPARED)
   $(_host_target)host-configure: $(HOST_STAMP_CONFIGURED)
   $(_host_target)host-compile: $(HOST_STAMP_BUILT) $(HOST_STAMP_INSTALLED)
diff --git a/include/package.mk b/include/package.mk
index ae613bf376..5165179cb1 100644
--- a/include/package.mk
+++ b/include/package.mk
@@ -187,6 +187,8 @@ define Build/CoreTargets
   $(call Build/Autoclean)
   $(call DefaultTargets)
 
+  $(DL_DIR)/$(FILE): FORCE
+
   download:
 	$(foreach hook,$(Hooks/Download),
 		$(call $(hook))$(sep)
diff --git a/scripts/download.pl b/scripts/download.pl
index 910e1e3a94..52b1e85a5d 100755
--- a/scripts/download.pl
+++ b/scripts/download.pl
@@ -277,6 +277,24 @@ foreach my $mirror (@ARGV) {
 push @mirrors, 'https://sources.openwrt.org';
 push @mirrors, 'https://mirror2.openwrt.org/sources';
 
+if (-f "$target/$filename") {
+	$hash_cmd and do {
+		if (system("cat '$target/$filename' | $hash_cmd > '$target/$filename.hash'")) {
+			die "Failed to generate hash for $filename\n";
+		}
+
+		my $sum = `cat "$target/$filename.hash"`;
+		$sum =~ /^(\w+)\s*/ or die "Could not generate file hash\n";
+		$sum = $1;
+
+		exit 0 if $sum eq $file_hash;
+
+		die "Hash of the local file $filename does not match (file: $sum, requested: $file_hash) - deleting download.\n";
+		unlink "$target/$filename";
+		cleanup();
+	};
+}
+
 while (!-f "$target/$filename") {
 	my $mirror = shift @mirrors;
 	$mirror or die "No more mirrors to try - giving up.\n";