Allow passing a writer function callback to DER_Encoder

2 files changed, 18 insertions, 10 deletions

diff --git a/src/lib/asn1/der_enc.cpp b/src/lib/asn1/der_enc.cpp
index c1ec010a0..99b833d27 100644
--- a/src/lib/asn1/der_enc.cpp
+++ b/src/lib/asn1/der_enc.cpp
@@ -68,7 +68,7 @@ void encode_length(std::vector<uint8_t>& encoded_length, size_t length)
 
 DER_Encoder::DER_Encoder(secure_vector<uint8_t>& vec)
    {
-   m_append_output_fn = [&vec](const uint8_t b[], size_t l)
+   m_append_output = [&vec](const uint8_t b[], size_t l)
       {
       vec.insert(vec.end(), b, b + l);
       };
@@ -76,7 +76,7 @@ DER_Encoder::DER_Encoder(secure_vector<uint8_t>& vec)
 
 DER_Encoder::DER_Encoder(std::vector<uint8_t>& vec)
    {
-   m_append_output_fn = [&vec](const uint8_t b[], size_t l)
+   m_append_output = [&vec](const uint8_t b[], size_t l)
       {
       vec.insert(vec.end(), b, b + l);
       };
@@ -154,7 +154,7 @@ secure_vector<uint8_t> DER_Encoder::get_contents()
    if(m_subsequences.size() != 0)
       throw Invalid_State("DER_Encoder: Sequence hasn't been marked done");
 
-   if(m_append_output_fn)
+   if(m_append_output)
       throw Invalid_State("DER_Encoder Cannot get contents when using output vector");
 
    secure_vector<uint8_t> output;
@@ -167,7 +167,7 @@ std::vector<uint8_t> DER_Encoder::get_contents_unlocked()
    if(m_subsequences.size() != 0)
       throw Invalid_State("DER_Encoder: Sequence hasn't been marked done");
 
-   if(m_append_output_fn)
+   if(m_append_output)
       throw Invalid_State("DER_Encoder Cannot get contents when using output vector");
 
    std::vector<uint8_t> output(m_default_outbuf.begin(), m_default_outbuf.end());
@@ -231,9 +231,9 @@ DER_Encoder& DER_Encoder::raw_bytes(const uint8_t bytes[], size_t length)
       {
       m_subsequences[m_subsequences.size()-1].add_bytes(bytes, length);
       }
-   else if(m_append_output_fn)
+   else if(m_append_output)
       {
-      m_append_output_fn(bytes, length);
+      m_append_output(bytes, length);
       }
    else
       {
@@ -257,10 +257,10 @@ DER_Encoder& DER_Encoder::add_object(ASN1_Tag type_tag, ASN1_Tag class_tag,
       {
       m_subsequences[m_subsequences.size()-1].add_bytes(hdr.data(), hdr.size(), rep, length);
       }
-   else if(m_append_output_fn)
+   else if(m_append_output)
       {
-      m_append_output_fn(hdr.data(), hdr.size());
-      m_append_output_fn(rep, length);
+      m_append_output(hdr.data(), hdr.size());
+      m_append_output(rep, length);
       }
    else
       {
diff --git a/src/lib/asn1/der_enc.h b/src/lib/asn1/der_enc.h
index f351817f9..135a70d07 100644
--- a/src/lib/asn1/der_enc.h
+++ b/src/lib/asn1/der_enc.h
@@ -23,6 +23,8 @@ class ASN1_Object;
 class BOTAN_PUBLIC_API(2,0) DER_Encoder final
    {
    public:
+      typedef std::function<void (const uint8_t[], size_t)> append_fn;
+
       /**
       * DER encode, writing to an internal buffer
       * Use get_contents or get_contents_unlocked to read the results
@@ -42,6 +44,12 @@ class BOTAN_PUBLIC_API(2,0) DER_Encoder final
       */
       DER_Encoder(std::vector<uint8_t>& vec);
 
+      /**
+      * DER encode, calling append to write output
+      * If this constructor is used, get_contents* may not be called.
+      */
+      DER_Encoder(append_fn append) : m_append_output(append) {}
+
       secure_vector<uint8_t> get_contents();
 
       std::vector<uint8_t> get_contents_unlocked();
@@ -203,7 +211,7 @@ class BOTAN_PUBLIC_API(2,0) DER_Encoder final
             std::vector< secure_vector<uint8_t> > m_set_contents;
          };
 
-      std::function<void (const uint8_t[], size_t)> m_append_output_fn;
+      append_fn m_append_output;
       secure_vector<uint8_t> m_default_outbuf;
       std::vector<DER_Sequence> m_subsequences;
    };