DER improvements

Let DER_Encoder write to a user specified vector instead of only to an
internal vector. This allows encoding to a std::vector without having
to first write to a locked vector and then copying out the result.

Add ASN1_Object::BER_encode convenience method. Replaces
X509_Object::BER_encode which had the same logic but was restricted to
a subtype. This replaces many cases where DER_Encoder was just used
to encode a single object (X509_DN, AlgorithmIdentifier, etc).

1 files changed, 22 insertions, 1 deletions

diff --git a/src/lib/asn1/der_enc.h b/src/lib/asn1/der_enc.h
index ebca73d33..f351817f9 100644
--- a/src/lib/asn1/der_enc.h
+++ b/src/lib/asn1/der_enc.h
@@ -10,6 +10,7 @@
 
 #include <botan/asn1_obj.h>
 #include <vector>
+#include <functional>
 
 namespace Botan {
 
@@ -22,6 +23,25 @@ class ASN1_Object;
 class BOTAN_PUBLIC_API(2,0) DER_Encoder final
    {
    public:
+      /**
+      * DER encode, writing to an internal buffer
+      * Use get_contents or get_contents_unlocked to read the results
+      * after all encoding is completed.
+      */
+      DER_Encoder() = default;
+
+      /**
+      * DER encode, writing to @param vec
+      * If this constructor is used, get_contents* may not be called.
+      */
+      DER_Encoder(secure_vector<uint8_t>& vec);
+
+      /**
+      * DER encode, writing to @param vec
+      * If this constructor is used, get_contents* may not be called.
+      */
+      DER_Encoder(std::vector<uint8_t>& vec);
+
       secure_vector<uint8_t> get_contents();
 
       std::vector<uint8_t> get_contents_unlocked();
@@ -183,7 +203,8 @@ class BOTAN_PUBLIC_API(2,0) DER_Encoder final
             std::vector< secure_vector<uint8_t> > m_set_contents;
          };
 
-      secure_vector<uint8_t> m_contents;
+      std::function<void (const uint8_t[], size_t)> m_append_output_fn;
+      secure_vector<uint8_t> m_default_outbuf;
       std::vector<DER_Sequence> m_subsequences;
    };