shill: Add Nl80211Attribute type.
This checkin is just a framework for the Nl80211Attribute type.
The Nl80211Attribute type encapsulates each attribute in an object.
This will enable the creation of an AttributeList type that can
encapsulate an arbitrary number of levels of nested attributes.
The next checkin includes all the types and all the attributes
necessary to use Nl80211Attribute. It also passes unittests.
BUG=chromium-os:36637
TEST=unittests.
Change-Id: Ide967812e5286526d37f3ac5d478ab5a4c358bd6
Reviewed-on: https://gerrit.chromium.org/gerrit/38973
Reviewed-by: mukesh agrawal <quiche@chromium.org>
Commit-Ready: Wade Guthrie <wdg@chromium.org>
Tested-by: Wade Guthrie <wdg@chromium.org>
diff --git a/nl80211_attribute.h b/nl80211_attribute.h
new file mode 100644
index 0000000..9ead8ee
--- /dev/null
+++ b/nl80211_attribute.h
@@ -0,0 +1,160 @@
+// Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef SHILL_NLATTRIBUTE_H_
+#define SHILL_NLATTRIBUTE_H_
+
+#include <linux/nl80211.h>
+#include <netlink/netlink.h>
+
+#include <map>
+#include <string>
+
+#include <base/memory/scoped_ptr.h>
+
+#include "shill/byte_string.h"
+
+struct nlattr;
+
+namespace shill {
+
+// Nl80211Attribute is an abstract base class that describes an attribute in a
+// netlink-80211 message. Child classes are type-specific and will define
+// Get*Value and Set*Value methods (where * is the type). A second-level of
+// child classes exist for each individual attribute type.
+//
+// An attribute has a name (which is really an enumerated value), a data type,
+// and a value. In an nlattr (the underlying format for an attribute in a
+// message), the data is stored as a blob without type information; the writer
+// and reader of the attribute must agree on the data type.
+class Nl80211Attribute {
+ public:
+ enum Type {
+ kTypeU8,
+ kTypeU16,
+ kTypeU32,
+ kTypeU64,
+ kTypeString,
+ kTypeFlag,
+ kTypeMsecs,
+ kTypeNested,
+ kTypeRaw,
+ kTypeError
+ };
+
+ Nl80211Attribute(nl80211_attrs name, const char *name_string,
+ Type type, const char *type_string);
+ virtual ~Nl80211Attribute() {}
+
+ virtual bool InitFromNlAttr(const nlattr *data);
+
+ // Static factory generates the appropriate Nl80211Attribute object from the
+ // raw nlattr data.
+ static Nl80211Attribute *NewFromNlAttr(nl80211_attrs name,
+ const nlattr *data);
+
+ // Accessors for the attribute's name and type information.
+ nl80211_attrs name() const { return name_; }
+ virtual const char *name_string() const { return name_string_; }
+ Type type() const { return type_; }
+ std::string type_string() const { return type_string_; }
+
+ // TODO(wdg): Since |data| is used, externally, to support |nla_parse_nested|,
+ // make it protected once all functionality has been brought inside the
+ // Nl80211Attribute classes.
+ //
+ // |data_| contains an 'nlattr *' but it's been stored as a ByteString.
+ // This returns a pointer to the data in the form that is intended.
+ const nlattr *data() const {
+ return reinterpret_cast<const nlattr *>(data_.GetConstData());
+ }
+
+ // TODO(wdg): GetRawData is used to support
+ // UserBoundNlMessage::GetRawAttributeData which, in turn, is used to support
+ // NL80211_ATTR_FRAME and NL80211_ATTR_KEY_SEQ. Remove this method (and that
+ // one) once those classes are fleshed-out.
+ //
+ // If successful, returns 'true' and sets *|value| to the raw attribute data
+ // (after the header) for this attribute. Otherwise, returns 'false' and
+ // leaves |value| unchanged.
+ bool GetRawData(ByteString *value) const;
+
+ // Fill a string with characters that represents the value of the attribute.
+ // If no attribute is found or if the type isn't trivially stringizable,
+ // this method returns 'false' and |value| remains unchanged.
+ virtual bool AsString(std::string *value) const = 0;
+
+ // Writes the raw attribute data to a string. For debug.
+ std::string RawToString() const;
+
+ protected:
+ // Raw data corresponding to the value in any of the child classes.
+ // TODO(wdg): When 'data()' is removed, move this to the Nl80211RawAttribute
+ // class.
+ ByteString data_;
+
+ private:
+ nl80211_attrs name_;
+ const char *name_string_;
+ Type type_;
+ const char *type_string_;
+};
+
+// Type-specific sub-classes. These provide their own type-specific data get
+// and set functions.
+
+class Nl80211U32Attribute : public Nl80211Attribute {
+ public:
+ static const char kMyTypeString[];
+ static const Type kType;
+ Nl80211U32Attribute(nl80211_attrs name, const char *name_string)
+ : Nl80211Attribute(name, name_string, kType, kMyTypeString) {}
+ bool InitFromNlAttr(const nlattr *data);
+ bool GetU32Value(uint32_t *value) const;
+ bool SetU32Value(uint32_t new_value);
+ bool AsString(std::string *value) const;
+
+ private:
+ uint32_t value_;
+};
+
+// TODO(wdg): Add more data types.
+
+class Nl80211RawAttribute : public Nl80211Attribute {
+ public:
+ static const char kMyTypeString[];
+ static const Type kType;
+ Nl80211RawAttribute(nl80211_attrs name, const char *name_string)
+ : Nl80211Attribute(name, name_string, kType, kMyTypeString) {}
+ bool InitFromNlAttr(const nlattr *data);
+ bool GetRawValue(const ByteString **value) const;
+ // Not supporting 'set' for raw data. This type is a "don't know" type to
+ // be used for user-bound massages (via InitFromNlAttr). The 'set' method
+ // is intended for building kernel-bound messages and shouldn't be used with
+ // raw data.
+ bool AsString(std::string *value) const;
+};
+
+// Attribute-specific sub-classes.
+
+class Nl80211AttributeDuration : public Nl80211U32Attribute {
+ public:
+ static const nl80211_attrs kName;
+ static const char kNameString[];
+ explicit Nl80211AttributeDuration()
+ : Nl80211U32Attribute(kName, kNameString) {}
+};
+
+class Nl80211AttributeGeneric : public Nl80211RawAttribute {
+ public:
+ explicit Nl80211AttributeGeneric(nl80211_attrs name);
+ const char *name_string() const;
+
+ private:
+ std::string name_string_;
+};
+
+} // namespace shill
+
+#endif // SHILL_NLATTRIBUTE_H_