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, 12 insertions, 13 deletions

diff --git a/src/lib/pubkey/dl_group/dl_group.cpp b/src/lib/pubkey/dl_group/dl_group.cpp
index 9bab123cb..6a2d21c8b 100644
--- a/src/lib/pubkey/dl_group/dl_group.cpp
+++ b/src/lib/pubkey/dl_group/dl_group.cpp
@@ -457,37 +457,36 @@ std::vector<uint8_t> DL_Group::DER_encode(Format format) const
    if(get_q().is_zero() && (format == ANSI_X9_57 || format == ANSI_X9_42))
       throw Encoding_Error("Cannot encode DL_Group in ANSI formats when q param is missing");
 
+   std::vector<uint8_t> output;
+   DER_Encoder der(output);
+
    if(format == ANSI_X9_57)
       {
-      return DER_Encoder()
-         .start_cons(SEQUENCE)
+      der.start_cons(SEQUENCE)
             .encode(get_p())
             .encode(get_q())
             .encode(get_g())
-         .end_cons()
-      .get_contents_unlocked();
+         .end_cons();
       }
    else if(format == ANSI_X9_42)
       {
-      return DER_Encoder()
-         .start_cons(SEQUENCE)
+      der.start_cons(SEQUENCE)
             .encode(get_p())
             .encode(get_g())
             .encode(get_q())
-         .end_cons()
-      .get_contents_unlocked();
+         .end_cons();
       }
    else if(format == PKCS_3)
       {
-      return DER_Encoder()
-         .start_cons(SEQUENCE)
+      der.start_cons(SEQUENCE)
             .encode(get_p())
             .encode(get_g())
-         .end_cons()
-      .get_contents_unlocked();
+         .end_cons();
       }
+   else
+      throw Invalid_Argument("Unknown DL_Group encoding " + std::to_string(format));
 
-   throw Invalid_Argument("Unknown DL_Group encoding " + std::to_string(format));
+   return output;
    }
 
 /*