From 44d21d74cf114063b750a6122ab79ab77ffc767f Mon Sep 17 00:00:00 2001
From: Brad Hards <bradh@frogmouth.net>
Date: Tue, 28 Aug 2007 21:23:43 +0000
Subject: [PATCH] Add a bit more information on the InfoContext class that
Justin just added.
CCMAIL: justin@affinix.com
svn path=/trunk/kdesupport/qca/; revision=705906
---
Mainpage.dox | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 52 insertions(+), 1 deletion(-)
diff --git a/Mainpage.dox b/Mainpage.dox
index 4a0d6ff6..180ed548 100644
--- a/Mainpage.dox
+++ b/Mainpage.dox
@@ -163,7 +163,7 @@
/** \page architecture Architecture
-\note You don't need to understand any of this to use %QCA. It is
+\note You don't need to understand any of this to use %QCA - it is
documented for those who are curious, and for anyone planning to
extend or modify %QCA.
@@ -296,11 +296,62 @@ because the plugins are often based on existing libraries.
return new opensslCipherContext( EVP_aes_128_cbc(), 0, this, type);
else
return 0;
+ }
\endcode
The resulting effect is that %QCA can ask the provider to provide an appropriate
Context object without worrying about how it is implemented.
+For features that are implemented with variable algorithms (for example, HashContext can
+support a wide range of algorithms - MD5, SHA0, and SHA1 in the example above; and
+CipherContext and MACContext can also do this), we need to be able to let applications
+determine which algorithms are supported. This is handled through the InfoContext class.
+A typical example is shown below:
+\code
+ class opensslInfoContext : public InfoContext
+ {
+ Q_OBJECT
+ public:
+ opensslInfoContext(Provider *p) : InfoContext(p)
+ {
+ }
+
+ Context *clone() const
+ {
+ return new opensslInfoContext(*this);
+ }
+
+ QStringList supportedHashTypes() const
+ {
+ QStringList list;
+ list += "sha1";
+ list += "sha0";
+ list += "md5";
+ return list;
+ }
+
+ // MAC and Cipher types can go in here
+ };
+\endcode
+
+Note that InfoContext is itself a feature, so you have to add it to the createContext()
+method for the provider, as shown below:
+\code
+ Context *createContext(const QString &type)
+ {
+ if ( type == "sha1" )
+ return new opensslHashContext( EVP_sha1(), this, type);
+ else if ( type == "sha0" )
+ return new opensslHashContext( EVP_sha(), this, type);
+ else if ( type == "md5" )
+ return new opensslHashContext( EVP_md5(), this, type);
+ else if ( type == "info" )
+ return new opensslInfoContext( this );
+ else
+ return 0;
+ }
+\endcode
+
*/
/** \page providers Providers