Fix X509_DN comparison

An issue in #1936 indicated that X509_DN operator< was not
behaving correctly. Indeed, DNs could compare in such a way
that DN1 < DN2 && DN2 < DN1. STL containers do not like this.

1 files changed, 46 insertions, 0 deletions

diff --git a/src/fuzzer/x509_dn.cpp b/src/fuzzer/x509_dn.cpp
new file mode 100644
index 000000000..dca6352e9
--- /dev/null
+++ b/src/fuzzer/x509_dn.cpp
@@ -0,0 +1,46 @@
+/*
+* (C) 2019 Jack Lloyd
+*
+* Botan is released under the Simplified BSD License (see license.txt)
+*/
+
+#include "fuzzers.h"
+#include <botan/x509_dn.h>
+#include <botan/ber_dec.h>
+#include <botan/hex.h>
+
+void fuzz(const uint8_t in[], size_t len)
+   {
+   const size_t half = len / 2;
+   Botan::X509_DN dn1;
+   Botan::X509_DN dn2;
+
+   try
+      {
+      Botan::BER_Decoder ber1(in, half);
+      dn1.decode_from(ber1);
+      ber1.verify_end();
+
+      Botan::BER_Decoder ber2(in + half, half);
+      dn2.decode_from(ber2);
+      ber2.verify_end();
+      }
+   catch(...) { return; }
+
+   const bool eq = dn1 == dn2;
+   const bool lt1 = dn1 < dn2;
+   const bool lt2 = dn2 < dn1;
+
+   if(lt1 == false && lt2 == false)
+      {
+      FUZZER_ASSERT_TRUE(eq);
+      }
+   else
+      {
+      // one is less than the other
+      FUZZER_ASSERT_TRUE(lt1 || lt2);
+
+      // it is not the case that both are less than the other
+      FUZZER_ASSERT_TRUE(!lt1 || !lt2);
+      }
+   }