5 files changed, 59 insertions, 5 deletions

diff --git a/src/lib/ffi/ffi.cpp b/src/lib/ffi/ffi.cpp
index b540a9b8e..74c576631 100644
--- a/src/lib/ffi/ffi.cpp
+++ b/src/lib/ffi/ffi.cpp
@@ -14,10 +14,10 @@
 
 namespace Botan_FFI {
 
-int ffi_error_exception_thrown(const char* func_name, const char* exn)
+int ffi_error_exception_thrown(const char* func_name, const char* exn, int rc)
    {
-   fprintf(stderr, "in %s exception %s\n", func_name, exn);
-   return BOTAN_FFI_ERROR_EXCEPTION_THROWN;
+   fprintf(stderr, "in %s exception '%s' returning %d\n", func_name, exn, rc);
+   return rc;
    }
 
 }
@@ -48,6 +48,9 @@ const char* botan_error_description(int err)
       case BOTAN_FFI_ERROR_EXCEPTION_THROWN:
          return "Exception thrown";
 
+      case BOTAN_FFI_ERROR_OUT_OF_MEMORY:
+         return "Out of memory";
+
       case BOTAN_FFI_ERROR_BAD_FLAG:
          return "Bad flag";
 
@@ -57,6 +60,9 @@ const char* botan_error_description(int err)
       case BOTAN_FFI_ERROR_BAD_PARAMETER:
          return "Bad parameter";
 
+      case BOTAN_FFI_ERROR_KEY_NOT_SET:
+         return "Key not set on object";
+
       case BOTAN_FFI_ERROR_NOT_IMPLEMENTED:
          return "Not implemented";
 
diff --git a/src/lib/ffi/ffi.h b/src/lib/ffi/ffi.h
index 676a451f1..9deefffb5 100644
--- a/src/lib/ffi/ffi.h
+++ b/src/lib/ffi/ffi.h
@@ -73,9 +73,11 @@ enum BOTAN_FFI_ERROR {
 
    BOTAN_FFI_ERROR_INSUFFICIENT_BUFFER_SPACE = -10,
    BOTAN_FFI_ERROR_EXCEPTION_THROWN = -20,
+   BOTAN_FFI_ERROR_OUT_OF_MEMORY = -21,
    BOTAN_FFI_ERROR_BAD_FLAG = -30,
    BOTAN_FFI_ERROR_NULL_POINTER = -31,
    BOTAN_FFI_ERROR_BAD_PARAMETER = -32,
+   BOTAN_FFI_ERROR_KEY_NOT_SET = -33,
    BOTAN_FFI_ERROR_NOT_IMPLEMENTED = -40,
    BOTAN_FFI_ERROR_INVALID_OBJECT = -50,
 
@@ -563,6 +565,18 @@ BOTAN_PUBLIC_API(2,8) int botan_block_cipher_name(botan_block_cipher_t cipher,
                                                   char* name, size_t* name_len);
 
 
+/**
+* Get the key length limits of this block cipher
+* @param cipher the object to read
+* @param out_minimum_keylength if non-NULL, will be set to minimum keylength of cipher
+* @param out_maximum_keylength if non-NULL, will be set to maximum keylength of cipher
+* @param out_keylength_modulo if non-NULL will be set to byte multiple of valid keys
+*/
+BOTAN_PUBLIC_API(2,8) int botan_block_cipher_query_keylen(botan_block_cipher_t,
+                                                          size_t* out_minimum_keylength,
+                                                          size_t* out_maximum_keylength,
+                                                          size_t* out_keylength_modulo);
+
 /*
 * Multiple precision integers
 */
diff --git a/src/lib/ffi/ffi_block.cpp b/src/lib/ffi/ffi_block.cpp
index fad492fd4..e19747d2b 100644
--- a/src/lib/ffi/ffi_block.cpp
+++ b/src/lib/ffi/ffi_block.cpp
@@ -85,4 +85,19 @@ int botan_block_cipher_name(botan_block_cipher_t cipher, char* name, size_t* nam
       return write_str_output(name, name_len, bc.name()); });
    }
 
+int botan_block_cipher_query_keylen(botan_block_cipher_t cipher,
+                                    size_t* out_minimum_keylength,
+                                    size_t* out_maximum_keylength,
+                                    size_t* out_keylength_modulo)
+   {
+   return BOTAN_FFI_DO(Botan::BlockCipher, cipher, bc, {
+      if(out_minimum_keylength)
+         *out_minimum_keylength = bc.minimum_keylength();
+      if(out_maximum_keylength)
+         *out_maximum_keylength = bc.maximum_keylength();
+      if(out_keylength_modulo)
+         *out_keylength_modulo = bc.key_spec().keylength_multiple();
+      });
+   }
+
 }
diff --git a/src/lib/ffi/ffi_util.h b/src/lib/ffi/ffi_util.h
index 9ff1b0e2f..afd359dbb 100644
--- a/src/lib/ffi/ffi_util.h
+++ b/src/lib/ffi/ffi_util.h
@@ -43,7 +43,8 @@ struct botan_struct
    struct NAME final : public Botan_FFI::botan_struct<TYPE, MAGIC> { explicit NAME(TYPE* x) : botan_struct(x) {} }
 
 // Declared in ffi.cpp
-int ffi_error_exception_thrown(const char* func_name, const char* exn);
+int ffi_error_exception_thrown(const char* func_name, const char* exn,
+                               int rc = BOTAN_FFI_ERROR_EXCEPTION_THROWN);
 
 template<typename T, uint32_t M>
 T& safe_get(botan_struct<T,M>* p)
@@ -69,7 +70,15 @@ int ffi_guard_thunk(const char* func_name, Thunk thunk)
       }
    catch(std::bad_alloc&)
       {
-      return ffi_error_exception_thrown(func_name, "bad_alloc");
+      return ffi_error_exception_thrown(func_name, "bad_alloc", BOTAN_FFI_ERROR_OUT_OF_MEMORY);
+      }
+   catch(Botan::Key_Not_Set& e)
+      {
+      return ffi_error_exception_thrown(func_name, e.what(), BOTAN_FFI_ERROR_KEY_NOT_SET);
+      }
+   catch(Botan::Invalid_Argument& e)
+      {
+      return ffi_error_exception_thrown(func_name, e.what(), BOTAN_FFI_ERROR_BAD_PARAMETER);
       }
    catch(std::exception& e)
       {
diff --git a/src/tests/test_ffi.cpp b/src/tests/test_ffi.cpp
index c0afd9ac2..5940a1009 100644
--- a/src/tests/test_ffi.cpp
+++ b/src/tests/test_ffi.cpp
@@ -860,6 +860,16 @@ class FFI_Unit_Tests final : public Test
 
             TEST_FFI_RC(16, botan_block_cipher_block_size, (cipher));
 
+            size_t min_keylen = 0, max_keylen = 0, mod_keylen = 0;
+            TEST_FFI_RC(0, botan_block_cipher_query_keylen, (cipher, nullptr, nullptr, nullptr));
+            TEST_FFI_RC(0, botan_block_cipher_query_keylen, (cipher, &min_keylen, nullptr, nullptr));
+            TEST_FFI_RC(0, botan_block_cipher_query_keylen, (cipher, nullptr, &max_keylen, nullptr));
+            TEST_FFI_RC(0, botan_block_cipher_query_keylen, (cipher, nullptr, nullptr, &mod_keylen));
+
+            result.test_eq("Expected min keylen", min_keylen, 16);
+            result.test_eq("Expected max keylen", max_keylen, 16);
+            result.test_eq("Expected mod keylen", mod_keylen, 1);
+
             TEST_FFI_OK(botan_block_cipher_set_key, (cipher, zero16.data(), zero16.size()));
 
             TEST_FFI_OK(botan_block_cipher_encrypt_blocks, (cipher, block.data(), block.data(), 1));