cosmos::ReceiveMessageHeader Class Reference

Wrapper for struct msghdr for receiving message via Socket::receiveMessage(). More...

#include <message_header.hxx>

Inheritance diagram for cosmos::ReceiveMessageHeader:

Classes
class	ControlMessage
	Wrapper for struct cmsghdr used for iterating over received control messages. More...
class	ControlMessageIterator
	Helper type for iterating over ControlMessage instances received in a ReceiveMessageHeader. More...

Public Member Functions
MessageFlags	flags () const
	Returns the MessageFlags provided by the last recvmsg() operation.
void	setControlBufferSize (const size_t bytes)
	Set the size of the buffer used for receiving ancillary messages.
void	clearControlBuffer ()
	No longer receive control messages.
ControlMessageIterator	begin ()
ControlMessageIterator	end ()
Public Member Functions inherited from cosmos::MessageHeaderBase< msghdr >
	MessageHeaderBase ()
	Create a MSGHDR initialized to all zeroes and with default flags applied.
void	clear ()
	Clear the complete system call structure with zeroes.
void	setIOFlags (const MessageFlags flags)
	Set the flags used for sending or receiving data.

Public Attributes
ReadIOVector	iovec
	Memory regions to receive data into.

Protected Member Functions
void	prepareReceive (SocketAddress *addr)
	Prepare a recvmsg() operation using the given optional source address storage.
void	postReceive (size_t received)
	Perform any cleanup or bookkeeping after a successful recvmsg() operation.
void	setAddress (SocketAddress &addr)
	Fill in the source address storage fields of the struct msghdr for the given address object.
struct msghdr *	rawHeader ()
const struct msghdr *	rawHeader () const
Protected Member Functions inherited from cosmos::MessageHeaderBase< msghdr >
void	resetAddress ()
	Reset the address portion of the msghdr struct.
void	setIov (IOVEC &iovec)
	Set the msg_iov fields of the msghdr struct based on the given iovector object.
MessageFlags	ioFlags () const
	Returns the currently set MessageFlags for send/receive.

Protected Attributes
std::vector< uint8_t >	m_control_buffer
	Optional buffer used to receive ancillary messages.
Protected Attributes inherited from cosmos::MessageHeaderBase< msghdr >
msghdr	m_header
	The low level struct msghdr
MessageFlags	m_io_flags
	The currently configured send/receive flags.

Friends
class	Socket

Detailed Description

Wrapper for struct msghdr for receiving message via Socket::receiveMessage().

This type holds extended data for receiving a message over a socket. For one it allows receiving data into multiple scattered memory regions using a ReadIOVector. Furthermore additional ancillary data can be received, if setup via setControlBufferSize(). The public iovec member is used for setting up the according memory regions for receiving. These settings will be applied when passing the ReceiveMessageHeader to Socket::receiveMessage() or one of its specializations.

This type implements an iterator interface to iterate over any received ancillary messages. Beware that ancillary data may arrive in a different order and payload/ancillary data combination than it was sent.

Definition at line 250 of file message_header.hxx.

Member Function Documentation

begin()

ControlMessageIterator cosmos::ReceiveMessageHeader::begin ( )

inline

Definition at line 416 of file message_header.hxx.

                                       {
                return ControlMessageIterator{*this};
        }

clearControlBuffer()

void cosmos::ReceiveMessageHeader::clearControlBuffer ( )

inline

No longer receive control messages.

Definition at line 412 of file message_header.hxx.

                                  {
                setControlBufferSize(0);
        }

end()

ControlMessageIterator cosmos::ReceiveMessageHeader::end ( )

inline

Definition at line 420 of file message_header.hxx.

                                     {
                return ControlMessageIterator{};
        }

flags()

MessageFlags cosmos::ReceiveMessageHeader::flags ( ) const

inline

Returns the MessageFlags provided by the last recvmsg() operation.

Definition at line 391 of file message_header.hxx.

                                   {
                return MessageFlags{m_header.msg_flags};
        }

postReceive()

void cosmos::ReceiveMessageHeader::postReceive ( size_t received )

inlineprotected

Perform any cleanup or bookkeeping after a successful recvmsg() operation.

Definition at line 430 of file message_header.hxx.

                                          {
                iovec.update(received);
        }

prepareReceive()

void cosmos::ReceiveMessageHeader::prepareReceive ( SocketAddress * addr )

protected

Prepare a recvmsg() operation using the given optional source address storage.

Definition at line 59 of file message_header.cxx.

                                                             {
        if (addr) {
                setAddress(*addr);
        } else {
                resetAddress();
        }
 
        setIov(iovec);
 
        if (!m_control_buffer.empty()) {
                m_header.msg_control = m_control_buffer.data();
                m_header.msg_controllen = m_control_buffer.size();
        }
}

rawHeader() [1/2]

struct msghdr * cosmos::ReceiveMessageHeader::rawHeader ( )

inlineprotected

Definition at line 437 of file message_header.hxx.

                                   {
                return &m_header;
        }

rawHeader() [2/2]

const struct msghdr * cosmos::ReceiveMessageHeader::rawHeader ( ) const

inlineprotected

Definition at line 441 of file message_header.hxx.

                                               {
                return &m_header;
        }

setAddress()

void cosmos::ReceiveMessageHeader::setAddress ( SocketAddress & addr )

protected

Fill in the source address storage fields of the struct msghdr for the given address object.

Definition at line 43 of file message_header.cxx.

                                                         {
        m_header.msg_name = reinterpret_cast<void*>(addr.basePtr());
        m_header.msg_namelen = addr.maxSize();
}

setControlBufferSize()

void cosmos::ReceiveMessageHeader::setControlBufferSize

(

const size_t

bytes

)

Set the size of the buffer used for receiving ancillary messages.

By default no ancillary messages will be received. Setting this buffer size expresses the intent to receive ControlMessages in future calls to Socket::receiveMessage() or one of its specializations. This setting remains active until clearControlBuffer() is called.

Note that receiving ancillary messages should not be taken lightly, especially with UNIX domain sockets. Other processes connected to this socket can now send file descriptors to this process, that will use up entries in the file descriptor table unless properly dealt with by the application.

Definition at line 48 of file message_header.cxx.

                                                                  {
        if (bytes == 0) {
                m_control_buffer.clear();
                return;
        } else if (bytes < sizeof(cmsghdr)) {
                cosmos_throw (RuntimeError("control buffer size smaller than control message header"));
        }
 
        m_control_buffer.resize(bytes);
}

Friends And Related Symbol Documentation

Socket

friend class Socket

friend

Definition at line 252 of file message_header.hxx.

Member Data Documentation

iovec

ReadIOVector cosmos::ReceiveMessageHeader::iovec

Memory regions to receive data into.

Definition at line 386 of file message_header.hxx.

m_control_buffer

std::vector<uint8_t> cosmos::ReceiveMessageHeader::m_control_buffer

protected

Optional buffer used to receive ancillary messages.

Definition at line 448 of file message_header.hxx.

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The documentation for this class was generated from the following files:

• include/net/message_header.hxx
• src/net/message_header.cxx