From dc679ab41fbacd8847227653eea520e24c9c7dcc Mon Sep 17 00:00:00 2001
From: Volker Birk <vb@pep-project.org>
Date: Thu, 25 Jun 2020 20:26:56 +0200
Subject: [PATCH] passphrase cache

---
 .hgignore           |  1 +
 passphrase_cache.cc | 34 ++++++++++++++++++++++++++++++++++
 passphrase_cache.hh | 43 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 78 insertions(+)
 create mode 100644 passphrase_cache.cc
 create mode 100644 passphrase_cache.hh

diff --git a/.hgignore b/.hgignore
index ea86dde..e5cac49 100644
--- a/.hgignore
+++ b/.hgignore
@@ -1,6 +1,7 @@
 syntax: glob
 *.o
 *.a
+*.d
 *.swp
 ws
 test_adapter
diff --git a/passphrase_cache.cc b/passphrase_cache.cc
new file mode 100644
index 0000000..e91a3ca
--- /dev/null
+++ b/passphrase_cache.cc
@@ -0,0 +1,34 @@
+#include "passphrase_cache.hh"
+
+namespace pEp {
+    void PassphraseCache::add(std::string passphrase)
+    {
+        std::lock_guard<std::mutex> lock(_mtx);
+        cleanup();
+        _cache.push_back({passphrase, clock::now()});
+    }
+
+    bool PassphraseCache::for_each_passphrase(passphrase_callee& callee)
+    {
+        std::lock_guard<std::mutex> lock(_mtx);
+        cleanup();
+
+        for (auto entry : _cache) {
+            if (callee(entry.passphrase))
+                return true;
+        }
+
+        return false;
+    }
+
+    void PassphraseCache::cleanup()
+    {
+        for (auto entry = _cache.begin(); entry != _cache.end(); ) {
+            if (entry->tp < clock::now() - _timeout)
+                _cache.erase(entry);
+            else
+                break;
+        }
+    }
+};
+
diff --git a/passphrase_cache.hh b/passphrase_cache.hh
new file mode 100644
index 0000000..67749f8
--- /dev/null
+++ b/passphrase_cache.hh
@@ -0,0 +1,43 @@
+#pragma once
+
+#include <list>
+#include <string>
+#include <chrono>
+#include <mutex>
+#include <functional>
+
+namespace pEp {
+    class PassphraseCache {
+        using clock = std::chrono::system_clock;
+        using time_point = std::chrono::time_point<clock>;
+        using duration = clock::duration;
+
+        struct cache_entry {
+            std::string passphrase;
+            time_point tp;
+        };
+
+        std::list<cache_entry> _cache;   
+        std::mutex _mtx;
+        duration _timeout;
+
+    public:
+        PassphraseCache() : _timeout(std::chrono::minutes(10)) { }
+        ~PassphraseCache() { }
+        PassphraseCache(const PassphraseCache& second) :
+            _cache(second._cache), _timeout(second._timeout) { }
+
+        // adding a passphrase to the cache, which will timeout
+        void add(std::string passphrase);
+
+        // for each passphrase call the callee until it returns true for a
+        // matching passphrase or no passphrases are left
+        // returns true if a passphrase was matching, false otherwise
+        using passphrase_callee = std::function<bool(std::string)>;
+        bool for_each_passphrase(passphrase_callee& callee);
+
+    protected:
+        void cleanup();
+    };
+};
+