Make exceptions easier to translate to error codes

Avoid throwing base Botan::Exception type, as it is difficult to
determine what the error is in that case.

Add Exception::error_code and Exception::error_type which allows
(for error code) more information about the error and (for error type)
allows knowing the error type without requiring a sequence of catches.

See GH #1742

1 files changed, 8 insertions, 5 deletions

diff --git a/src/lib/pubkey/pkcs8.cpp b/src/lib/pubkey/pkcs8.cpp
index f6d50256d..d299a98a4 100644
--- a/src/lib/pubkey/pkcs8.cpp
+++ b/src/lib/pubkey/pkcs8.cpp
@@ -105,7 +105,7 @@ secure_vector<uint8_t> PKCS8_decode(
       if(is_encrypted)
          {
          if(OIDS::lookup(pbe_alg_id.get_oid()) != "PBE-PKCS5v20")
-            throw Exception("Unknown PBE type " + pbe_alg_id.get_oid().as_string());
+            throw PKCS8_Exception("Unknown PBE type " + pbe_alg_id.get_oid().as_string());
 #if defined(BOTAN_HAS_PKCS5_PBES2)
          key = pbes2_decrypt(key_data, get_passphrase(), pbe_alg_id.get_parameters());
 #else
@@ -167,10 +167,13 @@ choose_pbe_params(const std::string& pbe_algo, const std::string& key_algo)
       }
 
    SCAN_Name request(pbe_algo);
-   if(request.arg_count() != 2)
-      throw Exception("Unsupported PBE " + pbe_algo);
-   if(request.algo_name() != "PBE-PKCS5v20" && request.algo_name() != "PBES2")
-      throw Exception("Unsupported PBE " + pbe_algo);
+
+   if(request.arg_count() != 2 ||
+      (request.algo_name() != "PBE-PKCS5v20" && request.algo_name() != "PBES2"))
+      {
+      throw Invalid_Argument("Unsupported PBE " + pbe_algo);
+      }
+
    return std::make_pair(request.arg(0), request.arg(1));
    }