Compute MAPI PR_ENTRYID for messages and attachments

In e-discovery applications, messages will often be referred to by a
MAPI PR_ENTRYID.  This is a computed property, as described here:

  http://pstsdk.codeplex.com/Thread/View.aspx?ThreadId=215111

Because this is a fairly useful property, and because it's relatively
hard to calculate, I feel it might be worth including somewhere in
pstsdk.

I wanted to implement a node::get_entry_id function, but because
get_entry_id needs access to the message store property bag, this would
have made the ndb layer depend on the ltp layer.

Thus, this patch provides a property_bag::get_entry_id() function, which
does not require any additional dependencies between layers.

pstsdk/ltp/propbag.h

@@ -79,6 +79,10 @@ class property_bag : public const_property_object
     //! \returns The node
     node& get_node() { return m_pbth->get_node(); }
 
+    //! \brief Get the MAPI entry id for this node's property bag.
+    //! \returns The MAPI entry id
+    std::vector<byte> get_entry_id() const;
+
 private:
     property_bag& operator=(const property_bag& other); // = delete
 
@@ -241,4 +245,25 @@ inline pstsdk::hnid_stream_device pstsdk::property_bag::open_prop_stream(prop_id
     else
         return m_pbth->get_heap_ptr()->open_stream(h_id);
 }
+
+inline std::vector<pstsdk::byte> pstsdk::property_bag::get_entry_id() const {
+    using namespace std;
+
+    // A MAPI entry id contains 4 leading 0 bytes, the data store ID, and
+    // the node ID.
+    vector<byte> entry_id(4, 0);
+
+    node store(get_node().get_db()->lookup_node(nid_message_store));
+    property_bag store_props(store);
+    vector<byte> store_id(store_props.read_prop<vector<byte> >(0x0ff9));
+    copy(store_id.begin(), store_id.end(),
+         insert_iterator<vector<byte> >(entry_id, entry_id.end()));
+
+    node_id nid(get_node().get_id());
+    for (int i = sizeof(node_id) - 1; i >= 0; --i)
+        entry_id.push_back((nid >> 8*i) & 0xff);
+
+    return entry_id;
+}
+
 #endif

pstsdk/pst/message.h

@@ -91,6 +91,11 @@ class attachment
     const property_bag& get_property_bag() const
         { return m_bag; }
 
+    //! \brief Get the MAPI entry ID of this attachment
+    //! \returns The MAPI entry ID of this attachment
+    std::vector<byte> get_entry_id() const
+        { return m_bag.get_entry_id(); }
+
 private:
     attachment& operator=(const attachment&); // = delete
     friend class message;
@@ -346,6 +351,11 @@ class message
     node_id get_id() const
         { return m_bag.get_node().get_id(); }
 
+    //! \brief Get the MAPI entry ID of this message
+    //! \returns The MAPI entry ID of this message
+    std::vector<byte> get_entry_id() const
+        { return m_bag.get_entry_id(); }
+
 private:
     message& operator=(const message&); // = delete
 

test/pstlevel.cpp

@@ -89,6 +89,28 @@ void process_pst(const pstsdk::pst& p)
     process_folder(root);
 }
 
+void test_entry_id(pstsdk::pst& p) {
+    using namespace std;
+    using namespace pstsdk;
+
+    message m(*p.message_begin());
+    attachment a(*m.attachment_begin());
+
+    const byte expected1_bytes[24] = {
+        0x00, 0x00, 0x00, 0x00, 0x6a, 0x55, 0x2b, 0x81, 0x3c, 0x43, 0xf9, 0x43,
+        0x84, 0xf1, 0x8b, 0x7d, 0xa2, 0x39, 0x3e, 0x95, 0x00, 0x20, 0x00, 0x24
+    };
+    vector<byte> expected1(expected1_bytes, expected1_bytes + 24);
+    assert(expected1 == m.get_entry_id());
+
+    const byte expected2_bytes[24] = {
+        0x00, 0x00, 0x00, 0x00, 0x6a, 0x55, 0x2b, 0x81, 0x3c, 0x43, 0xf9, 0x43,
+        0x84, 0xf1, 0x8b, 0x7d, 0xa2, 0x39, 0x3e, 0x95, 0x00, 0x00, 0x80, 0x25
+    };
+    vector<byte> expected2(expected2_bytes, expected2_bytes + 24);
+    assert(expected2 == a.get_entry_id());
+}
+
 void test_pstlevel()
 {
     using namespace pstsdk;
@@ -107,4 +129,7 @@ void test_pstlevel()
 
     // make sure searching by name works
     process_folder(uni.open_folder(L"Folder"));
+
+    // make sure we can calculate entry_id values
+    test_entry_id(s1);
 }