Add option to remove type fromt he jwt_header #26

include/jwt/impl/jwt.ipp

@@ -85,19 +85,16 @@ inline void jwt_header::decode(const jwt::string_view enc_str, std::error_code&
   if (alg_ != algorithm::NONE)
   {
     auto itr = payload_.find("typ");
-    if (itr == payload_.end()) {
-      ec = DecodeErrc::TypHeaderMiss;
-      return;
+
+    if (itr != payload_.end()) {
+      const auto& typ = itr.value().get<std::string>();
+      if (strcasecmp(typ.c_str(), "JWT")) {
+        ec = DecodeErrc::TypMismatch;
+        return;
+      }
+
+      typ_ = str_to_type(typ);
     }
-
-    const auto& typ = itr.value().get<std::string>();
-
-    if (strcasecmp(typ.c_str(), "JWT")) {
-      ec = DecodeErrc::TypMismatch;
-      return;
-    }
-
-    typ_ = str_to_type(typ);
   } else {
     //TODO:
   }
@@ -107,7 +104,8 @@ inline void jwt_header::decode(const jwt::string_view enc_str, std::error_code&
     auto ret = headers_.insert(it.key());
     if (!ret.second) {
       ec = DecodeErrc::DuplClaims;
-      break;
+      //ATTN: Dont stop the decode here
+      //Not a hard error.
     }
   }
 

include/jwt/jwt.hpp

@@ -51,7 +51,8 @@ namespace jwt {
  */
 enum class type
 {
-  JWT = 0,
+  NONE = 0,
+  JWT  = 1,
 };
 
 /**
@@ -63,6 +64,7 @@ inline enum type str_to_type(const jwt::string_view typ) noexcept
   assert (typ.length() && "Empty type string");
 
   if (!strcasecmp(typ.data(), "jwt")) return type::JWT;
+  else if(!strcasecmp(typ.data(), "none")) return type::NONE;
 
   throw std::runtime_error("Unknown token type");
 
@@ -410,6 +412,40 @@ public: // Exposed APIs
                       overwrite);
   }
 
+  /**
+   * Remove the header from JWT.
+   * NOTE: Special handling for removing type field
+   * from header. The typ_ is set to NONE when removed.
+   */
+  bool remove_header(const jwt::string_view hname)
+  {
+    if (!strcasecmp(hname.data(), "typ")) {
+      typ_ = type::NONE;
+      payload_.erase(hname.data());
+      return true;
+    }
+
+    auto itr = headers_.find(hname);
+    if (itr == std::end(headers_)) {
+      return false;
+    }
+    payload_.erase(hname.data());
+    headers_.erase(hname.data());
+
+    return true;
+  }
+
+  /**
+   * Checks if header with the given name
+   * is present or not.
+   */
+  bool has_header(const jwt::string_view hname)
+  {
+    if (!strcasecmp(hname.data(), "typ")) return typ_ != type::NONE;
+    return headers_.find(hname) != std::end(headers_);
+  }
+
+
   /**
    * Get the URL safe base64 encoded string
    * of the header.

tests/test_jwt_decode.cc

@@ -156,6 +156,22 @@ TEST (DecodeTest, DecodeHS512)
   EXPECT_TRUE (obj.payload().has_claim_with_value("sub", "nothing much"));
 }
 
+TEST (DecodeTest, TypHeaderMiss)
+{
+  using namespace jwt::params;
+
+  const char* enc_str = 
+    "eyJhbGciOiJIUzI1NiJ9."
+    "eyJleHAiOjE1MzM0NjE1NTMsImlhdCI6MTUxMzg2MjM3MSwiaWQiOiJhLWItYy1kLWUtZi0xLTItMyIsImlzcyI6ImFydW4ubXVyYWxpZGhhcmFuIiwic3ViIjoiYWRtaW4ifQ."
+    "pMWBLSWl1p4V958lfe_6ZhvgFMOQv9Eq5mlndVKFKkA";
+
+  std::error_code ec;
+  auto obj = jwt::decode(enc_str, algorithms({"none", "hs256"}), ec, verify(false));
+  std::cout << "Decode header: " << obj.header() << std::endl;
+
+  EXPECT_FALSE (ec);
+}
+
 int main(int argc, char* argv[]) {
   ::testing::InitGoogleTest(&argc, argv);
   return RUN_ALL_TESTS();

tests/test_jwt_encode.cc

@@ -25,6 +25,26 @@ TEST (EncodeTest, TestRemoveClaim)
   EXPECT_FALSE (obj.has_claim("sub"));
 }
 
+TEST (EncodeTest, TestRemoveTypHeader)
+{
+  using namespace jwt::params;
+
+  jwt::jwt_object obj{algorithm("hs256"), secret("secret")};
+
+  obj.add_claim("iss", "arun.muralidharan")
+     .add_claim("sub", "admin")
+     .add_claim("id", "a-b-c-d-e-f-1-2-3")
+     .add_claim("iat", 1513862371)
+     .add_claim("exp", std::chrono::system_clock::now());
+
+  EXPECT_TRUE (obj.header().has_header("typ"));
+  obj.header().remove_header("typ");
+  EXPECT_FALSE (obj.header().has_header("typ"));
+
+  std::cout << "Header: " << obj.header() << '\n';
+  std::cout << "Signature: " << obj.signature() << '\n';
+}
+
 TEST (EncodeTest, StrEncodeHS256_1)
 {
   using namespace jwt::params;