From c484ced63dcc80d2deb88ce84d90ce6882a8b8ee Mon Sep 17 00:00:00 2001
From: Arun M <arun11299@gmail.com>
Date: Sat, 16 Dec 2017 18:50:44 +0530
Subject: [PATCH] Exception and non exception based decoding

---
 include/jwt/error_codes.hpp      |  4 +++-
 include/jwt/impl/error_codes.ipp |  4 ++++
 include/jwt/impl/jwt.ipp         | 41 ++++++++++++++++++++++++++++----
 include/jwt/jwt.hpp              | 10 ++++++++
 4 files changed, 53 insertions(+), 6 deletions(-)

diff --git a/include/jwt/error_codes.hpp b/include/jwt/error_codes.hpp
index 08d2b7d..6b63a9b 100644
--- a/include/jwt/error_codes.hpp
+++ b/include/jwt/error_codes.hpp
@@ -26,7 +26,8 @@ enum class AlgorithmFailureSource
  */
 enum class DecodeErrc
 {
-  JsonParseError = 1,
+  EmptyAlgoList = 1,
+  JsonParseError,
   AlgHeaderMiss,
   TypHeaderMiss,
   TypMismatch,
@@ -42,6 +43,7 @@ enum class VerificationErrc
   InvalidIssuer,
   InvalidAudience,
   ImmatureSignature,
+  InvalidSignature,
 };
 
 /**
diff --git a/include/jwt/impl/error_codes.ipp b/include/jwt/impl/error_codes.ipp
index 672967c..d3bda2d 100644
--- a/include/jwt/impl/error_codes.ipp
+++ b/include/jwt/impl/error_codes.ipp
@@ -43,6 +43,8 @@ struct DecodeErrorCategory: std::error_category
   {
     switch (static_cast<DecodeErrc>(ev))
     {
+    case DecodeErrc::EmptyAlgoList:
+      return "empty algorithm list";
     case DecodeErrc::AlgHeaderMiss:
       return "missing algorithm header";
     case DecodeErrc::TypHeaderMiss:
@@ -82,6 +84,8 @@ struct VerificationErrorCategory: std::error_category
       return "invalid audience";
     case VerificationErrc::ImmatureSignature:
       return "immature signature";
+    case VerificationErrc::InvalidSignature:
+      return "invalid signature";
     };
 
     assert (0 && "Code not reached");
diff --git a/include/jwt/impl/jwt.ipp b/include/jwt/impl/jwt.ipp
index a5f31c8..6766a86 100644
--- a/include/jwt/impl/jwt.ipp
+++ b/include/jwt/impl/jwt.ipp
@@ -470,10 +470,15 @@ template <typename SequenceT, typename... Args>
 jwt_object decode(const string_view enc_str,
                   const string_view key,
                   const params::detail::algorithms_param<SequenceT>& algos,
+                  std::error_code& ec,
                   Args&&... args)
 {
+  ec.clear();
+  jwt_object obj;
+
   if (algos.get().size() == 0) {
-    throw DecodeError("Algorithms list cannot be empty");
+    ec = DecodeErrc::EmptyAlgoList;
+    return obj;
   }
 
   struct decode_params
@@ -495,7 +500,6 @@ jwt_object decode(const string_view enc_str,
   decode_params dparams{};
   set_decode_params(dparams, std::forward<Args>(args)...);
 
-  jwt_object obj;
   auto parts = jwt_object::three_parts(enc_str);
 
   //throws decode error
@@ -505,7 +509,9 @@ jwt_object decode(const string_view enc_str,
   obj.payload(jwt_payload{parts[1]});
 
   if (dparams.verify) {
-    std::error_code ec = obj.verify(dparams, algos);
+    ec = obj.verify(dparams, algos);
+
+    if (ec) return obj;
   }
 
   jwt_signature jsign{key};
@@ -514,18 +520,43 @@ jwt_object decode(const string_view enc_str,
   // Addition of '1' to account for the '.' character.
   auto l = parts[0].length() + 1 + parts[1].length();
 
+  //MemoryAllocationError is not caught
   verify_result_t res = jsign.verify(obj.header(), enc_str.substr(0, l), parts[2]);
   if (res.second) {
-    throw VerificationError(res.second.message());
+    ec = res.second;
+    return obj;
   }
 
   if (!res.first) {
-    throw VerificationError("Verification failed due to unknown reason");
+    ec = VerificationErrc::InvalidSignature;
+    return obj;
   }
 
   return obj; 
 }
 
+
+
+template <typename SequenceT, typename... Args>
+jwt_object decode(const string_view enc_str,
+                  const string_view key,
+                  const params::detail::algorithms_param<SequenceT>& algos,
+                  Args&&... args)
+{
+  std::error_code ec{};
+  auto jwt_obj = decode(enc_str,
+                        key,
+                        algos,
+                        ec,
+                        std::forward<Args>(args)...);
+
+  if (ec) {
+    jwt_throw_exception(ec);
+  }
+
+  return jwt_obj;
+}
+
 } // END namespace jwt
 
 
diff --git a/include/jwt/jwt.hpp b/include/jwt/jwt.hpp
index 2a9ba86..52401aa 100644
--- a/include/jwt/jwt.hpp
+++ b/include/jwt/jwt.hpp
@@ -722,11 +722,21 @@ private: // Data Members
 jwt_object jwt_decode(const string_view encoded_str, const string_view key, bool validate=true);
 
 /**
+ * NOTE: Memory allocation exceptions are not caught.
  */
 template <typename SequenceT, typename... Args>
 jwt_object decode(const string_view enc_str, 
                   const string_view key, 
                   const params::detail::algorithms_param<SequenceT>& algos, 
+                  std::error_code& ec,
+                  Args&&... args);
+
+/**
+ */
+template <typename SequenceT, typename... Args>
+jwt_object decode(const string_view enc_str,
+                  const string_view key,
+                  const params::detail::algorithms_param<SequenceT>& algos,
                   Args&&... args);