From 4c4121f164adac9dc9212372a02efd66d65cae97 Mon Sep 17 00:00:00 2001
From: Alexander Diemand <codieplusplus@apax.net>
Date: Mon, 27 Nov 2023 00:32:20 +0100
Subject: [PATCH] add: Gpg::decrypt_from_buffer

---
 build/test/CMakeLists.txt    |  4 ++--
 src/cpp/gpg.hpp.md           |  2 ++
 src/cpp/gpg_ctor.cpp.md      | 26 ++++++++++++++++++++++++++
 src/cpp/gpg_functions.cpp.md |  5 +++++
 test/cpp/utGpg.cpp.md        | 11 ++++++++---
 5 files changed, 43 insertions(+), 5 deletions(-)

diff --git a/build/test/CMakeLists.txt b/build/test/CMakeLists.txt
index 2213857..a566fd9 100644
--- a/build/test/CMakeLists.txt
+++ b/build/test/CMakeLists.txt
@@ -11,8 +11,8 @@ set(Boost_DEBUG OFF)
 set(Boost_USE_STATIC_LIBS OFF)
 set(Boost_USE_STATIC_RUNTIME OFF)
 set(Boost_USE_MULTITHREADED ON)
-find_package( Boost 1.74.0 REQUIRED COMPONENTS system date_time unit_test_framework contract)
-#include_directories(${Boost_INCLUDE_DIRS})
+find_package( Boost 1.83.0 REQUIRED COMPONENTS unit_test_framework)
+include_directories(${Boost_INCLUDE_DIRS})
 
 # mine
 include_directories(../src)
diff --git a/src/cpp/gpg.hpp.md b/src/cpp/gpg.hpp.md
index 730d204..247ee25 100644
--- a/src/cpp/gpg.hpp.md
+++ b/src/cpp/gpg.hpp.md
@@ -43,6 +43,8 @@ namespace [lxr](namespace.list) {
 
 >bool [decrypt_from_file](gpg_functions.cpp.md)(std::string const & fpath);
 
+>std::optional&lt;std::string&gt; [decrypt_from_buffer](gpg_functions.cpp.md)(std::string const & buffer);
+
 >private:
 
 >Gpg(Gpg const &) = delete;
diff --git a/src/cpp/gpg_ctor.cpp.md b/src/cpp/gpg_ctor.cpp.md
index 2613827..e28329e 100644
--- a/src/cpp/gpg_ctor.cpp.md
+++ b/src/cpp/gpg_ctor.cpp.md
@@ -13,6 +13,7 @@ struct Gpg::pimpl {
     std::ostream& ostream() { oss.reset(new std::ostringstream()); return *oss; }
     std::istream& istream() { return *iss; }
     bool decrypt_from_file(std::string const & fpath);
+    std::optional<std::string> decrypt_from_buffer(std::string const & buffer);
 
     private:
     gpgme_ctx_t ctx{nullptr};
@@ -181,6 +182,31 @@ bool Gpg::pimpl::decrypt_from_file(std::string const &p_fp)
     return true;
 }
 
+std::optional<std::string> Gpg::pimpl::decrypt_from_buffer(std::string const &p_buffer)
+{
+    gpgme_error_t err;
+    gpgme_data_t plain, cipher;
+    err = gpgme_data_new_from_mem(&cipher, p_buffer.c_str(), p_buffer.size(), 0);
+    if (err != GPG_ERR_NO_ERROR) { OUTPUT_GPGME_ERROR(err); return {}; }
+    err = gpgme_data_new(&plain);
+    if (err != GPG_ERR_NO_ERROR) { OUTPUT_GPGME_ERROR(err); gpgme_data_release(cipher); return {}; }
+    auto cleanup_data = [&](void) {
+        gpgme_data_release(plain);
+        gpgme_data_release(cipher);
+    };
+
+    err = gpgme_new(&ctx);
+    if (err != GPG_ERR_NO_ERROR) { OUTPUT_GPGME_ERROR(err); cleanup_data(); return {}; }
+
+    err = gpgme_op_decrypt(ctx, cipher, plain);
+    if (err != GPG_ERR_NO_ERROR) { OUTPUT_GPGME_ERROR(err); cleanup_data(); gpgme_release(ctx); return {}; }
+
+    gpgme_data_release(cipher);
+    size_t mlen;
+    const char *mptr = gpgme_data_release_and_get_mem(plain, &mlen);
+    return std::string(mptr, mlen);
+}
+
 Gpg::Gpg()
     : _pimpl(std::make_unique<pimpl>())
 {
diff --git a/src/cpp/gpg_functions.cpp.md b/src/cpp/gpg_functions.cpp.md
index 579576f..7f6d2c6 100644
--- a/src/cpp/gpg_functions.cpp.md
+++ b/src/cpp/gpg_functions.cpp.md
@@ -37,4 +37,9 @@ bool Gpg::decrypt_from_file(std::string const &fp)
     return _pimpl->decrypt_from_file(fp);
 }
 
+std::optional<std::string> Gpg::decrypt_from_buffer(std::string const &b)
+{
+    return _pimpl->decrypt_from_buffer(b);
+}
+
 ```
\ No newline at end of file
diff --git a/test/cpp/utGpg.cpp.md b/test/cpp/utGpg.cpp.md
index 3cdfcc0..2654727 100644
--- a/test/cpp/utGpg.cpp.md
+++ b/test/cpp/utGpg.cpp.md
@@ -52,11 +52,16 @@ BOOST_AUTO_TEST_CASE( gpg_check_non_private_key )
   BOOST_TEST_WARN(!gpg.has_private_key(addr), "the archiving process should not have access to this private key.");
 }
 
-BOOST_AUTO_TEST_CASE( gpg_encrypt_string )
+BOOST_AUTO_TEST_CASE( gpg_encrypt_decrypt_string )
 {
   lxr::Gpg gpg;
-  auto s = gpg.encrypt_to_key(addr, "hello world.");
-  BOOST_CHECK(s);
+  std::optional<std::string> cipher = gpg.encrypt_to_key(addr, "hello world.");
+  BOOST_CHECK(cipher);
+  if (cipher) {
+    std::optional<std::string> plain = gpg.decrypt_from_buffer(cipher.value());
+    BOOST_CHECK(plain);
+    BOOST_CHECK_EQUAL("hello world.", plain.value());
+  }
 }
 
 BOOST_AUTO_TEST_CASE( gpg_encrypt_stream )