promote filesize to a hashstring

It is a very simple hashstring, which is why it isn't contributing to
the usability of a list of them, but it is also trivial to check and
calculate, so it doesn't hurt checking it either as it can combined even
with the simplest other hashes greatly complicate attacks on them as you
suddenly need a same-size hash collision, which is usually a lot harder
to achieve.

1 files changed, 19 insertions, 6 deletions

diff --git a/test/libapt/hashsums_test.cc b/test/libapt/hashsums_test.cc
index 2159996ff..a19a0befd 100644
--- a/test/libapt/hashsums_test.cc
+++ b/test/libapt/hashsums_test.cc
@@ -163,30 +163,34 @@ TEST(HashSumsTest, FileBased)
 
    FileFd fd(__FILE__, FileFd::ReadOnly);
    EXPECT_TRUE(fd.IsOpen());
+   std::string FileSize;
+   strprintf(FileSize, "%llu", fd.FileSize());
 
    {
       Hashes hashes;
       hashes.AddFD(fd.Fd());
       HashStringList list = hashes.GetHashStringList();
       EXPECT_FALSE(list.empty());
-      EXPECT_EQ(4, list.size());
+      EXPECT_EQ(5, list.size());
       EXPECT_EQ(md5.Value(), list.find("MD5Sum")->HashValue());
       EXPECT_EQ(sha1.Value(), list.find("SHA1")->HashValue());
       EXPECT_EQ(sha256.Value(), list.find("SHA256")->HashValue());
       EXPECT_EQ(sha512.Value(), list.find("SHA512")->HashValue());
+      EXPECT_EQ(FileSize, list.find("Checksum-FileSize")->HashValue());
    }
-   unsigned long sz = fd.FileSize();
+   unsigned long long sz = fd.FileSize();
    fd.Seek(0);
    {
       Hashes hashes;
       hashes.AddFD(fd.Fd(), sz);
       HashStringList list = hashes.GetHashStringList();
       EXPECT_FALSE(list.empty());
-      EXPECT_EQ(4, list.size());
+      EXPECT_EQ(5, list.size());
       EXPECT_EQ(md5.Value(), list.find("MD5Sum")->HashValue());
       EXPECT_EQ(sha1.Value(), list.find("SHA1")->HashValue());
       EXPECT_EQ(sha256.Value(), list.find("SHA256")->HashValue());
       EXPECT_EQ(sha512.Value(), list.find("SHA512")->HashValue());
+      EXPECT_EQ(FileSize, list.find("Checksum-FileSize")->HashValue());
    }
    fd.Seek(0);
    {
@@ -279,37 +283,46 @@ TEST(HashSumsTest, HashStringList)
    EXPECT_EQ(NULL, list.find(""));
    EXPECT_EQ(NULL, list.find("MD5Sum"));
 
+   // empty lists aren't equal
    HashStringList list2;
    EXPECT_FALSE(list == list2);
    EXPECT_TRUE(list != list2);
 
+   // some hashes don't really contribute to usability
+   list.push_back(HashString("Checksum-FileSize", "29"));
+   EXPECT_FALSE(list.empty());
+   EXPECT_FALSE(list.usable());
+
    Hashes hashes;
    hashes.Add("The quick brown fox jumps over the lazy dog");
    list = hashes.GetHashStringList();
    EXPECT_FALSE(list.empty());
    EXPECT_TRUE(list.usable());
-   EXPECT_EQ(4, list.size());
+   EXPECT_EQ(5, list.size());
    EXPECT_TRUE(NULL != list.find(NULL));
    EXPECT_TRUE(NULL != list.find(""));
    EXPECT_TRUE(NULL != list.find("MD5Sum"));
+   EXPECT_TRUE(NULL != list.find("Checksum-FileSize"));
    EXPECT_TRUE(NULL == list.find("ROT26"));
 
    _config->Set("Acquire::ForceHash", "MD5Sum");
    EXPECT_FALSE(list.empty());
    EXPECT_TRUE(list.usable());
-   EXPECT_EQ(4, list.size());
+   EXPECT_EQ(5, list.size());
    EXPECT_TRUE(NULL != list.find(NULL));
    EXPECT_TRUE(NULL != list.find(""));
    EXPECT_TRUE(NULL != list.find("MD5Sum"));
+   EXPECT_TRUE(NULL != list.find("Checksum-FileSize"));
    EXPECT_TRUE(NULL == list.find("ROT26"));
 
    _config->Set("Acquire::ForceHash", "ROT26");
    EXPECT_FALSE(list.empty());
    EXPECT_FALSE(list.usable());
-   EXPECT_EQ(4, list.size());
+   EXPECT_EQ(5, list.size());
    EXPECT_TRUE(NULL == list.find(NULL));
    EXPECT_TRUE(NULL == list.find(""));
    EXPECT_TRUE(NULL != list.find("MD5Sum"));
+   EXPECT_TRUE(NULL != list.find("Checksum-FileSize"));
    EXPECT_TRUE(NULL == list.find("ROT26"));
 
    _config->Clear("Acquire::ForceHash");