Improve PEM detection for asn1 printer

1 files changed, 22 insertions, 5 deletions

diff --git a/src/cli/asn1.cpp b/src/cli/asn1.cpp
index 8a424aad8..65f38c060 100644
--- a/src/cli/asn1.cpp
+++ b/src/cli/asn1.cpp
@@ -9,6 +9,7 @@
 #if defined(BOTAN_HAS_ASN1)
 
 #include <botan/asn1_print.h>
+#include <botan/data_src.h>
 
 #if defined(BOTAN_HAS_PEM_CODEC)
   #include <botan/pem.h>
@@ -31,6 +32,18 @@ class ASN1_Printer final : public Command
          return "Decode and print file with ASN.1 Basic Encoding Rules (BER)";
          }
 
+      bool first_n(const std::vector<uint8_t>& data, size_t n, uint8_t b)
+         {
+         if(data.size() < n)
+            return false;
+
+         for(size_t i = 0; i != n; ++i)
+            if(data[i] != b)
+               return false;
+
+         return true;
+         }
+
       void go() override
          {
          const std::string input = get_arg("file");
@@ -42,26 +55,30 @@ class ASN1_Printer final : public Command
          const size_t value_column = 60;
          const size_t initial_level = 0;
 
-         std::vector<uint8_t> contents;
+         std::vector<uint8_t> file_contents = slurp_file(input);
+         std::vector<uint8_t> data;
 
-         if(flag_set("pem") || (input.size() > 4 && input.substr(input.size() - 4) == ".pem"))
+         if(flag_set("pem") ||
+            (input.size() > 4 && input.substr(input.size() - 4) == ".pem") ||
+            (file_contents.size() > 20 && first_n(file_contents, 5, '-')))
             {
 #if defined(BOTAN_HAS_PEM_CODEC)
             std::string pem_label;
-            contents = unlock(Botan::PEM_Code::decode(slurp_file_as_str(input), pem_label));
+            Botan::DataSource_Memory src(file_contents);
+            data = unlock(Botan::PEM_Code::decode(src, pem_label));
 #else
             throw CLI_Error_Unsupported("PEM decoding not available in this build");
 #endif
             }
          else
             {
-            contents = slurp_file(input);
+            data.swap(file_contents);
             }
 
          Botan::ASN1_Pretty_Printer printer(print_limit, bin_limit, print_context_specific,
                                             initial_level, value_column, max_depth);
 
-         printer.print_to_stream(output(), contents.data(), contents.size());
+         printer.print_to_stream(output(), data.data(), data.size());
          }
    };