/*

* (C) 2015,2016 Jack Lloyd

*

* Botan is released under the Simplified BSD License (see license.txt)

*/

#include "fuzzers.h"

#include <botan/hex.h>

#include <botan/internal/eme_pkcs.h>

namespace {

std::vector<uint8_t> simple_pkcs1_unpad(const uint8_t in[], size_t len) {

   if(len < 10) {

      throw Botan::Decoding_Error("bad len");

   }

   if(in[0] != 0 || in[1] != 2) {

      throw Botan::Decoding_Error("bad header field");

   }

   for(size_t i = 2; i < len; ++i) {

      if(in[i] == 0) {

         if(i < 10) {  // at least 8 padding bytes required

            throw Botan::Decoding_Error("insufficient padding bytes");

         }

         return std::vector<uint8_t>(in + i + 1, in + len);

      }

   }

   throw Botan::Decoding_Error("delim not found");

}

}  // namespace

void fuzz(std::span<const uint8_t> in) {

   static Botan::EME_PKCS1v15 pkcs1;

   std::vector<uint8_t> lib_result;

   std::vector<uint8_t> ref_result;

   bool lib_rejected = false;

   bool ref_rejected = false;

   try {

      lib_result.resize(in.size());

      auto written = (static_cast<Botan::EncryptionPaddingScheme*>(&pkcs1))->unpad(lib_result, in);

      lib_rejected = !written.has_value().as_bool();

      lib_result.resize(written.value_or(0));

   } catch(Botan::Decoding_Error&) {

      lib_rejected = true;

   }

   try {

      ref_result = simple_pkcs1_unpad(in.data(), in.size());

   } catch(Botan::Decoding_Error& e) {

      ref_rejected = true;

   }

   if(lib_rejected == true && ref_rejected == false) {

      FUZZER_WRITE_AND_CRASH("Library rejected input accepted by ref " << Botan::hex_encode(ref_result));

   } else if(ref_rejected == true && lib_rejected == false) {

      FUZZER_WRITE_AND_CRASH("Library accepted input rejected by ref " << Botan::hex_encode(lib_result));

   }

   // otherwise the two implementations agree

}