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Kea
1.9.9-git
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Kea
1.9.9-git
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The forwarder of socket sessions. More...
#include <socketsession.h>
Inheritance diagram for isc::util::io::SocketSessionForwarder:Classes | |
| struct | ForwarderImpl |
Public Member Functions | |
| SocketSessionForwarder (const std::string &unix_file) | |
| The constructor. More... | |
| virtual | ~SocketSessionForwarder () |
| The destructor. More... | |
| virtual void | close () |
| Close the connection to the receiver. More... | |
| virtual void | connectToReceiver () |
| Establish a connection to the receiver. More... | |
| virtual void | push (int sock, int family, int type, int protocol, const struct sockaddr &local_end, const struct sockaddr &remote_end, const void *data, size_t data_len) |
| Forward a socket session to the receiver. More... | |
| Public Member Functions inherited from isc::util::io::BaseSocketSessionForwarder | |
| virtual | ~BaseSocketSessionForwarder () |
Additional Inherited Members | |
| Protected Member Functions inherited from isc::util::io::BaseSocketSessionForwarder | |
| BaseSocketSessionForwarder () | |
The forwarder of socket sessions.
An object of this class maintains a UNIX domain socket (normally expected to be connected to a SocketSessionReceiver object) and forwards socket sessions to the receiver.
See the description of Socket session utility for other details of how the session forwarding works.
Definition at line 194 of file socketsession.h.
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explicit |
The constructor.
It's constructed with path information of the intended receiver, but does not immediately establish a connection to the receiver; connectToReceiver() must be called to establish it. These are separated so that an object of class can be initialized (possibly as an attribute of a higher level application class object) without knowing the receiver is ready for accepting new forwarders. The separate connect interface allows the object to be reused when it detects connection failure and tries to re-establish it after closing the failed one.
On construction, it also installs a signal filter for SIGPIPE to ignore it. Since this class uses a stream-type connected UNIX domain socket, if the receiver (abruptly) closes the connection a subsequent write operation on the socket would trigger a SIGPIPE signal, which kills the caller process by default. This behavior would be undesirable in many cases, so this implementation always disables the signal.
This approach has some drawbacks, however; first, since signal handling is process (or thread) wide, ignoring it may not what the application wants. On the other hand, if the application changes how the signal is handled after instantiating this class, the new behavior affects the class operation. Secondly, even if ignoring the signal is the desired operation, it's a waste to set the filter every time this class object is constructed. It's sufficient to do it once. We still adopt this behavior based on the observation that in most cases applications would like to ignore SIGPIPE (or simply doesn't care about it) and that this class is not instantiated so often (so the wasteful setting overhead should be marginal). On the other hand, doing it every time is beneficial if the application is threaded and different threads create different forwarder objects (and if signals work per thread).
| SocketSessionError | unix_file is invalid as a path name of a UNIX domain socket. |
| Unexpected | Error in setting a filter for SIGPIPE (see above) |
| std::bad_alloc | resource allocation failure |
| unix_file | Path name of the receiver. |
Definition at line 86 of file socketsession.cc.
References isc::util::io::SocketSessionForwarder::ForwarderImpl::fd_, isc::flex_option::impl, isc_throw, isc_throw_assert, isc::util::io::SocketSessionForwarder::ForwarderImpl::sock_un_, and isc::util::io::SocketSessionForwarder::ForwarderImpl::sock_un_len_.
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virtual |
The destructor.
If a connection has been established, it's automatically closed in the destructor.
Definition at line 120 of file socketsession.cc.
References close(), and isc::util::io::SocketSessionForwarder::ForwarderImpl::fd_.
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virtual |
Close the connection to the receiver.
The connection must have been established by connectToReceiver(). As long as it's met this method is exception free.
| BadValue | The connection hasn't been established. |
Implements isc::util::io::BaseSocketSessionForwarder.
Definition at line 176 of file socketsession.cc.
References isc::util::io::SocketSessionForwarder::ForwarderImpl::fd_, and isc_throw.
Referenced by connectToReceiver(), and ~SocketSessionForwarder().
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virtual |
Establish a connection to the receiver.
This method establishes a connection to the receiver at the path given on construction. It makes the underlying UNIX domain socket non blocking, so this method (or subsequent push() calls) does not block.
| BadValue | The method is called while an already established connection is still active. |
| SocketSessionError | A system error in socket operation. |
Implements isc::util::io::BaseSocketSessionForwarder.
Definition at line 128 of file socketsession.cc.
References close(), isc::util::io::internal::convertSockAddr(), isc::util::io::SocketSessionForwarder::ForwarderImpl::fd_, isc_throw, isc::util::io::SocketSessionForwarder::ForwarderImpl::sock_un_, isc::util::io::SocketSessionForwarder::ForwarderImpl::sock_un_len_, and isc::util::io::SOCKSESSION_BUFSIZE.
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virtual |
Forward a socket session to the receiver.
This method takes a set of parameters that represent a single socket session, renders them in the "wire" format according to the internal protocol (see Socket session utility) and forwards them to the receiver through the UNIX domain connection.
The connection must have been established by connectToReceiver().
For simplicity and for the convenience of detecting application errors, this method imposes some restrictions on the parameters:
AF_INET or AF_INET6 sa_family) member of the local and remote end points must be equal to the family parameterdata_len must not be 0 and data must not be NULL)Since the underlying UNIX domain socket is non blocking (see the description for the constructor), a call to this method should either return immediately or result in exception (in case of "would block").
| BadValue | The method is called before establishing a connection or given parameters are invalid. |
| SocketSessionError | A system error in socket operation, including the case where the write operation would block. |
| sock | The socket file descriptor |
| family | The address family (such as AF_INET6) of the socket |
| type | The socket type (such as SOCK_DGRAM) of the socket |
| protocol | The transport protocol (such as IPPROTO_UDP) of the socket |
| local_end | The local end point of the session in the form of sockaddr. |
| remote_end | The remote end point of the session in the form of sockaddr. |
| data | A pointer to the beginning of the memory region for the session data |
| data_len | The size of the session data in bytes. |
Implements isc::util::io::BaseSocketSessionForwarder.
Definition at line 185 of file socketsession.cc.
References isc::util::io::SocketSessionForwarder::ForwarderImpl::buf_, isc::util::OutputBuffer::clear(), isc::util::io::SocketSessionForwarder::ForwarderImpl::fd_, isc::util::OutputBuffer::getData(), isc::util::OutputBuffer::getLength(), isc::util::io::internal::getSALength(), isc_throw, isc_throw_assert, isc::util::io::send_fd(), isc::util::OutputBuffer::skip(), isc::util::OutputBuffer::writeData(), isc::util::OutputBuffer::writeUint16At(), and isc::util::OutputBuffer::writeUint32().
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1.8.9.1 