<em>by value</em>, they can be understood as pointers into the packet data with added type
information providing parsing functions.
+ Packet parsers are \e only used within the packet framework. You should never allocate a new
+ parser instance directly, you should the Packet library let that do for you (either by having
+ the parser as a packet parser in a packet type or by having a member in the packet parser which
+ allocates the parser as a sub-parser).
+
Parsers are built hierarchically. A high-level parser will return other parsers when accessing
an element (Example: Asking an EthernetParser for the ethertype field by calling the parsers \c
type() member will return an \c UInt16 parser). The lowest level building blocks then return the
complex parsers provide type specific access members. Assigning a value to a parser will change
the underlying representation (the packet data).
- More complex parsers (especially those representing a collection of values) provide an
- additional wrapper class for mutating access (e.g. Parse_Vector provides a container wrapper
- with am STL compatible random-access sequence interface). See the documentation of the specific
- parser for the wrapper specification.
+ Parsers can be grouped into several categories. These categories are not all defined rigorously
+ but are nevertheless helpful when working with the parsers:
+ \li <em>\ref parserimpl_value</em> provide the lowest level parsers (e.g. senf::Parse_UInt16 which
+ returns an integer value).
+ \li <em>\ref parserimpl_collection</em> are parsers which model a collection of sub-elements like
+ senf::Parse_List or senf::Parse_Vector.
+ \li <em>\ref parserimpl_composite</em> collect several fields of arbitrary type into a new
+ parser. Parsers defined using the \ref packetparsermacros fall under this category.
+ \li <em>\ref parserimpl_packet</em> are used to define a packet type.
+
+ \warning Parsers are like iterators: They are invalidated <em>whenever the size of the packet's
+ data is changed</em>. You should not store a parser anywhere. If you want to keep a parser
+ reference, use the senf::SafePacketParser wrapper. You still will need to take extra care to
+ ensure the parser is not invalidated.
+
+ \section parserimpl Packet parser categories
Every parser is derived from senf::PacketParserBase. This class provides the necessary
- housekeeping information and provides the parsers with access to the data.
+ housekeeping information and provides the parsers with access to the data. You may in principle
+ define arbitrary methods as parser members (e.g. methods to calculate a checksum, methods
+ processing fields in some way and so on). You should however be very wary to access data outside
+ the range assigned to the packet (the range starting at \c i() and with a size of senf::bytes()
+ bytes).
+
+ Each parser type has specific features
+
+ \subsection parserimpl_value Value parsers
+
+ For a parser \a SomeParser to be a value parser, the following expressions must be valid:
+ \code
+ // SomeParser must have a 'value_type', The 'value_type' must be default constructible, copy
+ // constructible and assignable
+ SomeParser::value_type v;
+
+ // An instance of 'SomeParser' must have a 'value' member which returns a value which may be
+ // assigned to a variable of type 'value_type'
+ v = p.someParserField().value()
+
+ // It must be possible to assign a new value using the 'value' member
+ p.someParserField().value(v)
+ \endcode
+
+ If at all possible, the 'value_type' should not reference the packet data using iterators or
+ pointers, it should hold a copy of the value (it's Ok for \c value() to return such a reference
+ as long as assigning it to a \c value_type variable will copy the value).
+
+ \see parseint
+
+ \subsection parserimpl_collection Collection parsers
+
+ A collection parser \a SomeParser should model STL containers. The parsers themselves will
+ probably only // provide a reduced interface, but the collection parser should have a \c
+ collection member which is a wrapper providing the full interface.
+ \code
+ SomeParser::container c (p.someParserField());
+ \endcode
+
+ You will probably only very seldom need to implement a completely new collection
+ parser. Instead, you can rely on senf::Parse_Vector or senf::Parse_List and implement new
+ policies.
+
+ \see parsecollection
+
+ \subsection parserimpl_composite Composite parsers
+
+ If possible, composite parsers should be implemented using the \ref packetparsermacros. In
+ addition to the normal parser requirements, these macros ensure, that for each field,
+ <em>fieldname</em><tt>_t</tt> is a typedef for the fields parser and
+ <em>fieldname</em><tt>_offset</tt> is the offset of the field in bytes from the beginning of the
+ parser (either a constant for fixed size parsers or a member function for dynamically sized
+ parsers). When defining composite parsers without the help of the \ref packetparsermacros, you
+ should provide those same members.
+
+ \subsection parserimpl_packet Packet parsers
+
+ Packet parsers are composite parsers with relaxed requirements. Since a packet parser will never
+ be used as a sub-parser (it will not be used within another composite parser or as value type in
+ a collection parser), the value returned by senf::bytes for this parser must not necessarily
+ cover the complete packet (e.g. if the packet has a trailer, the trailer will live outside the
+ range given by senf::bytes). You may define any member you want to have in your packets field
+ interface. These members may access the packet data in any way. You just need to ensure, that
+ the integration into the packet-type is correct (the senf::PacketTypeMixin will by default use
+ senf::bytes() to find the end of the header).
+
+ <hr>
*/
#ifndef HH_PacketParser_
#include <boost/utility/enable_if.hpp>
#include <boost/type_traits.hpp>
#include <boost/optional.hpp>
-#include "Utils/SafeBool.hh"
+#include "../Utils/safe_bool.hh"
#include "PacketTypes.hh"
#include "PacketData.hh"
+#include "ParseHelpers.hh"
-#include "PacketParser.mpp"
+//#include "PacketParser.mpp"
///////////////////////////////hh.p////////////////////////////////////////
namespace senf {
+
+ class Packet;
/** \brief Parser Base class
- Parsers come in two favors: fixed and dynamically sized parsers. A <em>fixed size
+ Parsers come in two flavors: fixed and dynamically sized parsers. A <em>fixed size
parser</em> has a constant size, it will always parse a fixed number of bytes. The low-level
'final' parsers (like the integer parsers) are fixed size parsers as are composite parsers
built up only of fixed-size fields.
typedef detail::packet::difference_type difference_type; ///< Signed integral type
typedef detail::packet::byte byte; ///< Unsigned 8bit value, the raw value type
typedef PacketData * state_type; ///< Type of the 'state' parameter
+ typedef PacketParserBase parser_base_type; ///< Base type of the next parser
///////////////////////////////////////////////////////////////////////////
///\name Structors and default members
container does not hold at least \a size bytes
beginning at \a i. */
- bool check(size_type size); ///< Check size of data container
+ bool check(size_type size) const; ///< Check size of data container
/**< \returns \c true, if the data container holds at least
\a size beginning at i(), \c false otherwise. */
- void validate(size_type size); ///< Validate size of data container
+ void validate(size_type size) const; ///< Validate size of data container
/**< \throws TruncatedPacketException if the raw data
container does not hold at least \a size bytes
beginning at i(). */
implementation. Re-implement this member in your own
parsers if needed. */
+ Packet packet() const; ///< Get packet this parser is parsing from
+ /**< \important This member should only be used from packet
+ parsers when access to previous or following packets is
+ needed e.g. for calculating checksums etc. */
+
private:
- data_iterator end();
+ data_iterator end() const;
data_iterator i_;
PacketData * data_;
struct init_bytes : public detail::ParserInitBytes<Parser>
{};
+# ifndef DOXYGEN
+ template <class Parser>
+ typename boost::enable_if<
+ boost::is_base_of<PacketParserBase, Parser>,
+ Parser >::type
+ operator<<(Parser target, Parser source);
+# else
/** \brief Generic parser copying
+
This operator allows to copy the values of identical parsers. This operation does \e not
depend on the parsers detailed implementation, it will just replace the data bytes of the
target parser with those from the source parser. This allows to easily copy around complex
\ingroup packetparser
*/
template <class Parser>
- typename boost::enable_if<
- boost::is_base_of<PacketParserBase, Parser>,
- Parser >::type
- operator<<(Parser target, Parser source);
+ Parser operator<<(Parser target, Parser source);
+# endif
+# ifndef DOXYGEN
+ template <class Parser, class Value>
+ typename boost::enable_if_c <
+ boost::is_base_of<PacketParserBase, Parser>::value
+ && ! boost::is_base_of<PacketParserBase, Value>::value,
+ Parser >::type
+ operator<<(Parser target, Value const & value);
+# else
/** \brief Generic parser value assignment
This operator allows to assign a value to parsers which implement a <tt>value(</tt>\a
\ingroup packetparser
*/
template <class Parser, class Value>
+ Parser operator<<(Parser target, Value const & value);
+# endif
+
+# ifndef DOXYGEN
+ template <class Parser, class Value>
typename boost::enable_if_c <
boost::is_base_of<PacketParserBase, Parser>::value
&& ! boost::is_base_of<PacketParserBase, Value>::value,
Parser >::type
- operator<<(Parser target, Value const & value);
-
- /** \defgroup packetparsermacros Helper macros for defining new packet parsers
-
- To simplify the definition of simple packet parsers, several macros are provided. Before
- using these macros you should familiarize yourself with the packet parser interface as
- described in senf::PacketParserBase.
-
- These macros simplify providing the above defined interface. A typical packet declaration
- using these macros has the following form (This is a concrete example from the definition of
- the ethernet packet in <tt>DefaultBundle/EthernetPacket.hh</tt>)
-
- \dontinclude EthernetPacket.hh
- \skipline struct Parse_EthVLan : public PacketParserBase
- \until };
-
- The macros take care of the following:
- \li They define the accessor functions returning parsers of the given type.
- \li They automatically calculate the offset of the fields from the preceding fields.
- \li The macros provide a definition for \c init()
- \li The macros define the \c bytes(), \c fixed_bytes and \c init_bytes members as needed.
-
- You may define either a fixed or a dynamically sized parser. Fixed size parsers are defined
- using \ref SENF_PACKET_PARSER_DEFINE_FIXED_FIELDS, dynamically sized parsers are defined
- using \ref SENF_PACKET_PARSER_DEFINE_FIELDS. The different members are implemented such
- that:
-
- \li The needed parser constructor is defined
- \li \c init() calls \c defaultInit(). \c defaultInit() is defined to call \c init() on each
- of the fields.
- \li \c bytes() (on dynamically sized parser) respectively \c fixed_bytes (on fixed size
- parsers) is defined to return the sum of the sizes of all fields.
- \li On dynamically sized parsers, \c init_bytes is defined to return the sum of the
- \c init_size's of all fields
-
- The central definition macros are \ref SENF_PACKET_PARSER_DEFINE_FIXED_FIELDS and \ref
- SENF_PACKET_PARSER_DEFINE_FIELDS. The argument to both has the same structure. It is a
- (boost preprocessor style) sequence of field definitions where each field definition
- provides the builder macro to use and the name and type of the field to define:
- \code
- SENF_PACKET_PARSER_DEFINE[_FIXED]_FIELDS(
- (( <builder> )( <name>, <type> ))
- ...
- )
- \endcode
-
- For each field, this command will define
- \li A method \a name() returning an instance of the \a type parser
- \li \a name<tt>_t</tt> as a typedef for \a type, the fields value
- \li \a name<tt>_offset</tt> to give the offset of the field from the beginning of the
- parser. If the parser is a fixed size parser, this will be a static constant, otherwise
- it will be a method.
-
- The \a builder argument selects, how the field is defined
- \li <tt>Field</tt> defines a field and increments the current position by the size of the
- field
- \li <tt>OverlayField</tt> defines a field like <tt>Field</tt> but does \e not increment the
- position. In the above example, this is used to overlay the different bitfield parsers:
- All overlaying bitfield parser except the last one (the one with the highest bit
- numbers) is marked as OverlayField.
-
- The \a name argument defines the name of the accessor method.
-
- The \a type argument is the parser to return for that field. Since none of the arguments may
- contain a comma, <em>This argument cannot be a multi-parameter template</em>. Always use
- typedefs to access templated parsers as shown above.
-
- The \ref SENF_PACKET_PARSER_INIT macro defines the constructor and the \c init() member. If
- you want to provide your own \c init() implementation, use \ref
- SENF_PACKET_PARSER_NO_INIT. The first statement in your init method should probably to call
- \c defaultInit(). This will call the \c init() member of all the fields. Afterwards you can
- set up the field values as needed:
- \code
- struct SomePacket : public senf::PacketParserBase
- {
- SENF_PACKET_PARSER_NO_INIT(SomePacket);
-
- typedef senf::Parse_UInt8 Parse_Type;
- typedef senf::Parse_Vector< senf::Parse_UInt32,
- senf::SimpleVectorSizer<senf::Parse_UInt16>
- > Parse_Elements;
-
- SENF_PACKET_PARSER_DEFINE_FIELDS(
- ((Field)( type, Parse_Type ))
- ((Field)( elements, Parse_Elements ))
- );
-
- void init() const {
- defaultInit();
- type() = 0x01;
- elements().push_back(0x01020304u);
- }
- }
- \endcode
-
- \ingroup packetparser
- */
-
- /** \brief Define initialization members of a parser
-
- This macro defines the packet parser constructor and the \c init() member. \c init() is
- defined to just call \c defaultInit() which is defined by the other macros to call \c init()
- on each of the parsers fields.
-
- \ingroup packetparsermacros
- \hideinitializer
- */
-# define SENF_PACKET_PARSER_INIT(name) \
- name(data_iterator i, state_type s) : senf::PacketParserBase(i,s) {} \
- void init() const { defaultInit(); }
-
- /** \brief Define initialization members of a parser except init()
-
- This macro is like SENF_PACKET_PARSER_INIT but does \e not define \c init(). This allows you
- to provide your own implementation. You should call \c defaultInit() first before
- initializing your data fields.
-
- \ingroup packetparsermacros
- \hideinitializer
- */
-# define SENF_PACKET_PARSER_NO_INIT(name) \
- name(data_iterator i, state_type s) : senf::PacketParserBase(i,s) {}
-
- /** \brief Define fields for a dynamically sized parser
-
- Define the fields as specified in \a fields. This macro supports dynamically sized
- subfields, the resulting parser will be dynamically sized.
-
- \ingroup packetparsermacros
- \hideinitializer
- */
-# define SENF_PACKET_PARSER_DEFINE_FIELDS(fields) \
- SENF_PACKET_PARSER_I_DEFINE_FIELDS(0,fields)
-
- /** \brief Define fields for a dynamically sized parser (with offset)
-
- Define the fields as specified in \a fields. This macro supports dynamically sized
- subfields, the resulting parser will be dynamically sized.
-
- The \a offset argument gives the byte offset at which to start parsing the fields. This
- helps defining extended parser deriving from a base parser:
- \code
- struct ExtendedParser : public BaseParser
- {
- ExtendedParser(data_iterator i, state_type s) : BaseParser(i,s) {}
-
- SENF_PACKET_PARSER_DEFINE_FIELDS_OFFSET(senf::bytes(BaseParser(*this)),
- ( ... fields ... ) );
-
- void init() {
- BaseParser::init();
- defaultInit();
- // other init code
- }
- }
- \endcode
-
- \ingroup packetparsermacros
- \hideinitializer
- */
-# define SENF_PACKET_PARSER_DEFINE_FIELDS_OFFSET(offset,fields) \
- SENF_PACKET_PARSER_I_DEFINE_FIELDS(offset,fields)
-
- /** \brief Define fields for a fixed size parser
-
- Define the fields as specified in \a fields. This macro only supports fixed size
- subfields, the resulting parser will also be a fixed size parser.
-
- \ingroup packetparsermacros
- \hideinitializer
- */
-# define SENF_PACKET_PARSER_DEFINE_FIXED_FIELDS(fields) \
- SENF_PACKET_PARSER_I_DEFINE_FIXED_FIELDS(0,fields)
+ operator<<(Parser target, boost::optional<Value> const & value);
+# else
+ /** \brief Generic parser value assignment
- /** \brief Define fields for a fixed size parser
+ This operator allows to assign a value to parsers which implement a <tt>value(</tt>\a
+ value<tt>)</tt> member. This special version allows to assign optional values: IF the
+ optional value is not set, the assignment will be skipped.
- Define the fields as specified in \a fields. This macro only supports fixed size
- subfields, the resulting parser will also be a fixed size parser.
+ This operator allows to use a common syntax for assigning values or parsers to a parser.
- The \a offset argument gives the byte offset at which to start parsing the fields. This
- helps defining extended parser deriving from a base parser:
- \code
- struct ExtendedParser : public BaseParser
- {
- ExtendedParser(data_iterator i, state_type s) : BaseParser(i,s) {}
-
- SENF_PACKET_PARSER_DEFINE_FIXED_FIELDS_OFFSET(BaseParser::fixed_bytes,
- ( ... fields ... ) );
-
- void init() {
- BaseParser::init();
- defaultInit();
- // other init code
- }
- }
- \endcode
-
- \ingroup packetparsermacros
- \hideinitializer
+ \ingroup packetparser
*/
-# define SENF_PACKET_PARSER_DEFINE_FIXED_FIELDS_OFFSET(offset,fields) \
- SENF_PACKET_PARSER_I_DEFINE_FIXED_FIELDS(offset,fields)
+ template <class Parser, class Value>
+ Parser operator<<(Parser target, boost::optional<Value> const & value);
+# endif
/** \brief Default parser parsing nothing
*/
struct VoidPacketParser
: public PacketParserBase
{
- SENF_PACKET_PARSER_INIT(VoidPacketParser);
+# include SENF_FIXED_PARSER()
+ SENF_PARSER_FINALIZE(VoidPacketParser);
};
/** \brief Iterator re-validating Parser wrapper
location will \e not be updated accordingly and therefore the parser will be
invalid.
- Additionally a SafePacketparser has an uninitialized state. The only allowed operations in
+ Additionally a SafePacketParser has an uninitialized state. The only allowed operations in
this state are the boolean test for validity and assigning another parser.
+
+ \ingroup packetparser
*/
template <class Parser>
class SafePacketParser
- : public SafeBool< SafePacketParser<Parser> >
+ : public safe_bool< SafePacketParser<Parser> >
{
public:
///////////////////////////////////////////////////////////////////////////
///////////////////////////////hh.e////////////////////////////////////////
#endif
-#if !defined(SENF_PACKETS_DECL_ONLY) && !defined(HH_PacketParser_i_)
+#if !defined(HH_Packets__decls_) && !defined(HH_PacketParser_i_)
#define HH_PacketParser_i_
#include "PacketParser.cci"
#include "PacketParser.ct"
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