Refactor random data generation

Add new RandomDataProvider object and implement existing random number
generation in terms of that.  This enables end users to supply their
own random data providers.

1 files changed, 65 insertions, 0 deletions

diff --git a/libtests/random.cc b/libtests/random.cc
new file mode 100644
index 00000000..644fdd91
--- /dev/null
+++ b/libtests/random.cc
@@ -0,0 +1,65 @@
+#include <qpdf/QUtil.hh>
+#include <qpdf/InsecureRandomDataProvider.hh>
+#include <qpdf/SecureRandomDataProvider.hh>
+#include <iostream>
+
+class BogusRandomDataProvider: public RandomDataProvider
+{
+  public:
+    virtual ~BogusRandomDataProvider()
+    {
+    }
+    BogusRandomDataProvider()
+    {
+    }
+    virtual void provideRandomData(unsigned char* data, size_t len)
+    {
+        for (size_t i = 0; i < len; ++i)
+        {
+            data[i] = static_cast<unsigned char>(i & 0xff);
+        }
+    }
+};
+
+int main()
+{
+    long r1 = QUtil::random();
+    long r2 = QUtil::random();
+    if (r1 == r2)
+    {
+        std::cout << "fail: two randoms were the same\n";
+    }
+    InsecureRandomDataProvider irdp;
+    irdp.provideRandomData(reinterpret_cast<unsigned char*>(&r1), 4);
+    irdp.provideRandomData(reinterpret_cast<unsigned char*>(&r2), 4);
+    if (r1 == r2)
+    {
+        std::cout << "fail: two insecure randoms were the same\n";
+    }
+    SecureRandomDataProvider srdp;
+    srdp.provideRandomData(reinterpret_cast<unsigned char*>(&r1), 4);
+    srdp.provideRandomData(reinterpret_cast<unsigned char*>(&r2), 4);
+    if (r1 == r2)
+    {
+        std::cout << "fail: two secure randoms were the same\n";
+    }
+    BogusRandomDataProvider brdp;
+    QUtil::setRandomDataProvider(&brdp);
+    r1 = QUtil::random();
+    r2 = QUtil::random();
+    if (r1 != r2)
+    {
+        std::cout << "fail: two bogus randoms were different\n";
+    }
+    unsigned char buf[4];
+    QUtil::initializeWithRandomBytes(buf, 4);
+    if (! ((buf[0] == 0) &&
+           (buf[1] == 1) &&
+           (buf[2] == 2) &&
+           (buf[3] == 3)))
+    {
+        std::cout << "fail: bogus random didn't provide correct bytes\n";
+    }
+    std::cout << "random: end of tests\n";
+    return 0;
+}