-- --
-- S p e c --
-- --
--- Copyright (C) 2001-2005 Ada Core Technologies, Inc. --
+-- Copyright (C) 2001-2010, AdaCore --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
-- Multicast is available only on systems which provide support for this
-- feature, so it is not available if Multicast is not supported, or not
--- installed. In particular Multicast is not available with the Windows
--- version.
+-- installed.
--- The VMS implementation has implemented using the DECC RTL Socket API,
+-- The VMS implementation was implemented using the DECC RTL Socket API,
-- and is thus subject to limitations in the implementation of this API.
-- VxWorks cross ports fully implement this package
with Ada.Streams;
with Ada.Unchecked_Deallocation;
-with System;
+with Interfaces.C;
+
+with System.OS_Constants;
+with System.Storage_Elements;
package GNAT.Sockets is
-- Sockets are designed to provide a consistent communication facility
- -- between applications. This package provides an Ada-like interface
- -- similar to that proposed as part of the BSD socket layer.
+ -- between applications. This package provides an Ada binding to the
+ -- the de-facto standard BSD sockets API. The documentation below covers
+ -- only the specific binding provided by this package. It assumes that
+ -- the reader is already familiar with general network programming and
+ -- sockets usage. A useful reference on this matter is W. Richard Stevens'
+ -- "UNIX Network Programming: The Sockets Networking API"
+ -- (ISBN: 0131411551).
-- GNAT.Sockets has been designed with several ideas in mind
-- notification of an asynchronous connect failure is delivered in the
-- write socket set (POSIX) instead of the exception socket set (NT).
- -- Here is a typical example of what you can do:
+ -- The example below demonstrates various features of GNAT.Sockets:
-- with GNAT.Sockets; use GNAT.Sockets;
-- Socket_Level,
-- (Reuse_Address, True));
- -- -- Join a multicast group
-
- -- Set_Socket_Option
- -- (Socket,
- -- IP_Protocol_For_IP_Level,
- -- (Add_Membership, Inet_Addr (Group), Any_Inet_Addr));
-
-- -- Controls the live time of the datagram to avoid it being
-- -- looped forever due to routing errors. Routers decrement
-- -- the TTL of every datagram as it traverses from one network
-- Bind_Socket (Socket, Address);
+ -- -- Join a multicast group
+
+ -- -- Portability note: On Windows, this option may be set only
+ -- -- on a bound socket.
+
+ -- Set_Socket_Option
+ -- (Socket,
+ -- IP_Protocol_For_IP_Level,
+ -- (Add_Membership, Inet_Addr (Group), Any_Inet_Addr));
+
-- -- If this socket is intended to send messages, provide the
-- -- receiver socket address.
-- Set_Socket_Option
-- (Socket,
-- IP_Protocol_For_IP_Level,
- -- (Add_Membership, Inet_Addr (Group), Any_Inet_Addr));
-
- -- Set_Socket_Option
- -- (Socket,
- -- IP_Protocol_For_IP_Level,
-- (Multicast_TTL, 1));
-- Set_Socket_Option
-- Bind_Socket (Socket, Address);
+ -- Set_Socket_Option
+ -- (Socket,
+ -- IP_Protocol_For_IP_Level,
+ -- (Add_Membership, Inet_Addr (Group), Any_Inet_Addr));
+
-- Address.Addr := Inet_Addr (Group);
-- Address.Port := 55505;
-- end Ping;
-- begin
- -- -- Indicate whether the thread library provides process
- -- -- blocking IO. Basically, if you are not using FSU threads
- -- -- the default is ok.
-
- -- Initialize (Process_Blocking_IO => False);
+ -- Initialize;
-- Ping.Start;
-- Pong.Start;
-- Ping.Stop;
-- Finalize;
-- end PingPong;
- procedure Initialize (Process_Blocking_IO : Boolean := False);
- -- Initialize must be called before using any other socket routines. The
- -- Process_Blocking_IO parameter indicates whether the thread library
- -- provides process-blocking or thread-blocking input/output operations.
- -- In the former case (typically with FSU threads) GNAT.Sockets should be
- -- initialized with a value of True to provide task-blocking IO through an
- -- emulation mechanism. Only the first call to Initialize is taken into
- -- account (further calls will be ignored). Note that with the default
- -- value of Process_Blocking_IO, this operation is a no-op on UNIX
- -- platforms, but applications should make sure to call it if portability
- -- is expected: some platforms (such as Windows) require initialization
- -- before any other socket operations.
+ package SOSC renames System.OS_Constants;
+ -- Renaming used to provide short-hand notations throughout the sockets
+ -- binding. Note that System.OS_Constants is an internal unit, and the
+ -- entities declared therein are not meant for direct access by users,
+ -- including through this renaming.
+
+ procedure Initialize;
+ pragma Obsolescent
+ (Entity => Initialize,
+ Message => "explicit initialization is no longer required");
+ -- Initialize must be called before using any other socket routines.
+ -- Note that this operation is a no-op on UNIX platforms, but applications
+ -- should make sure to call it if portability is expected: some platforms
+ -- (such as Windows) require initialization before any socket operation.
+ -- This is now a no-op (initialization and finalization are done
+ -- automatically).
+
+ procedure Initialize (Process_Blocking_IO : Boolean);
+ pragma Obsolescent
+ (Entity => Initialize,
+ Message => "passing a parameter to Initialize is no longer supported");
+ -- Previous versions of GNAT.Sockets used to require the user to indicate
+ -- whether socket I/O was process- or thread-blocking on the platform.
+ -- This property is now determined automatically when the run-time library
+ -- is built. The old version of Initialize, taking a parameter, is kept
+ -- for compatibility reasons, but this interface is obsolete (and if the
+ -- value given is wrong, an exception will be raised at run time).
+ -- This is now a no-op (initialization and finalization are done
+ -- automatically).
procedure Finalize;
+ pragma Obsolescent
+ (Entity => Finalize,
+ Message => "explicit finalization is no longer required");
-- After Finalize is called it is not possible to use any routines
-- exported in by this package. This procedure is idempotent.
+ -- This is now a no-op (initialization and finalization are done
+ -- automatically).
type Socket_Type is private;
-- Sockets are used to implement a reliable bi-directional point-to-point,
No_Socket : constant Socket_Type;
+ type Selector_Type is limited private;
+ type Selector_Access is access all Selector_Type;
+ -- Selector objects are used to wait for i/o events to occur on sockets
+
+ Null_Selector : constant Selector_Type;
+ -- The Null_Selector can be used in place of a normal selector without
+ -- having to call Create_Selector if the use of Abort_Selector is not
+ -- required.
+
+ -- Timeval_Duration is a subtype of Standard.Duration because the full
+ -- range of Standard.Duration cannot be represented in the equivalent C
+ -- structure. Moreover, negative values are not allowed to avoid system
+ -- incompatibilities.
+
+ Immediate : constant Duration := 0.0;
+
+ Timeval_Forever : constant := 2.0 ** (SOSC.SIZEOF_tv_sec * 8 - 1) - 1.0;
+ Forever : constant Duration :=
+ Duration'Min (Duration'Last, Timeval_Forever);
+
+ subtype Timeval_Duration is Duration range Immediate .. Forever;
+
+ subtype Selector_Duration is Timeval_Duration;
+ -- Timeout value for selector operations
+
+ type Selector_Status is (Completed, Expired, Aborted);
+ -- Completion status of a selector operation, indicated as follows:
+ -- Complete: one of the expected events occurred
+ -- Expired: no event occurred before the expiration of the timeout
+ -- Aborted: an external action cancelled the wait operation before
+ -- any event occurred.
+
Socket_Error : exception;
-- There is only one exception in this package to deal with an error during
-- a socket routine. Once raised, its message contains a string describing
type Family_Type is (Family_Inet, Family_Inet6);
-- Address family (or protocol family) identifies the communication domain
- -- and groups protocols with similar address formats. IPv6 will soon be
- -- supported.
+ -- and groups protocols with similar address formats.
type Mode_Type is (Socket_Stream, Socket_Datagram);
-- Stream sockets provide connection-oriented byte streams. Datagram
-- more data can be transmitted. Neither transmission nor reception can be
-- performed with Shut_Read_Write.
- type Port_Type is new Natural;
- -- Classical port definition. No_Port provides a special value to
- -- denote uninitialized port. Any_Port provides a special value
- -- enabling all ports.
+ type Port_Type is range 0 .. 16#ffff#;
+ -- TCP/UDP port number
Any_Port : constant Port_Type;
- No_Port : constant Port_Type;
+ -- All ports
+
+ No_Port : constant Port_Type;
+ -- Uninitialized port number
type Inet_Addr_Type (Family : Family_Type := Family_Inet) is private;
- -- An Internet address depends on an address family (IPv4 contains 4
- -- octets and Ipv6 contains 16 octets). Any_Inet_Addr is a special value
- -- treated like a wildcard enabling all addresses. No_Inet_Addr provides a
- -- special value to denote uninitialized inet addresses.
+ -- An Internet address depends on an address family (IPv4 contains 4 octets
+ -- and IPv6 contains 16 octets). Any_Inet_Addr is a special value treated
+ -- like a wildcard enabling all addresses. No_Inet_Addr provides a special
+ -- value to denote uninitialized inet addresses.
Any_Inet_Addr : constant Inet_Addr_Type;
No_Inet_Addr : constant Inet_Addr_Type;
Broadcast_Inet_Addr : constant Inet_Addr_Type;
+ Loopback_Inet_Addr : constant Inet_Addr_Type;
+
+ -- Useful constants for IPv4 multicast addresses
+
+ Unspecified_Group_Inet_Addr : constant Inet_Addr_Type;
+ All_Hosts_Group_Inet_Addr : constant Inet_Addr_Type;
+ All_Routers_Group_Inet_Addr : constant Inet_Addr_Type;
type Sock_Addr_Type (Family : Family_Type := Family_Inet) is record
Addr : Inet_Addr_Type (Family);
Host_Error : exception;
-- Exception raised by the two following procedures. Once raised, its
-- message contains a string describing the error code. This exception is
- -- raised when an host entry can not be retrieved.
+ -- raised when an host entry cannot be retrieved.
function Get_Host_By_Address
(Address : Inet_Addr_Type;
function Get_Host_By_Name
(Name : String) return Host_Entry_Type;
-- Return host entry structure for the given host name. Here name is
- -- either a host name, or an IP address. If Name is an IP address, this is
- -- equivalent to Get_Host_By_Address (Inet_Addr (Name)).
+ -- either a host name, or an IP address. If Name is an IP address, this
+ -- is equivalent to Get_Host_By_Address (Inet_Addr (Name)).
function Host_Name return String;
-- Return the name of the current host
Service_Error : exception;
-- Comment required ???
- -- Errors are described by an enumeration type. There is only one
- -- exception Socket_Error in this package to deal with an error during a
- -- socket routine. Once raised, its message contains the error code
- -- between brackets and a string describing the error code.
+ -- Errors are described by an enumeration type. There is only one exception
+ -- Socket_Error in this package to deal with an error during a socket
+ -- routine. Once raised, its message contains the error code between
+ -- brackets and a string describing the error code.
-- The name of the enumeration constant documents the error condition
+ -- Note that on some platforms, a single error value is used for both
+ -- EWOULDBLOCK and EAGAIN. Both errors are therefore always reported as
+ -- Resource_Temporarily_Unavailable.
type Error_Type is
(Success,
Connection_Timed_Out,
Too_Many_References,
Resource_Temporarily_Unavailable,
+ Broken_Pipe,
Unknown_Host,
Host_Name_Lookup_Failure,
Non_Recoverable_Error,
-- with a socket. Options may exist at multiple protocol levels in the
-- communication stack. Socket_Level is the uppermost socket level.
- type Level_Type is (
- Socket_Level,
- IP_Protocol_For_IP_Level,
- IP_Protocol_For_UDP_Level,
- IP_Protocol_For_TCP_Level);
+ type Level_Type is
+ (Socket_Level,
+ IP_Protocol_For_IP_Level,
+ IP_Protocol_For_UDP_Level,
+ IP_Protocol_For_TCP_Level);
-- There are several options available to manipulate sockets. Each option
-- has a name and several values available. Most of the time, the value is
-- a boolean to enable or disable this option.
- type Option_Name is (
- Keep_Alive, -- Enable sending of keep-alive messages
- Reuse_Address, -- Allow bind to reuse local address
- Broadcast, -- Enable datagram sockets to recv/send broadcast packets
- Send_Buffer, -- Set/get the maximum socket send buffer in bytes
- Receive_Buffer, -- Set/get the maximum socket recv buffer in bytes
- Linger, -- Shutdown wait for msg to be sent or timeout occur
- Error, -- Get and clear the pending socket error
- No_Delay, -- Do not delay send to coalesce packets (TCP_NODELAY)
- Add_Membership, -- Join a multicast group
- Drop_Membership, -- Leave a multicast group
- Multicast_TTL, -- Indicate the time-to-live of sent multicast packets
- Multicast_Loop); -- Sent multicast packets are looped to the local socket
+ type Option_Name is
+ (Keep_Alive, -- Enable sending of keep-alive messages
+ Reuse_Address, -- Allow bind to reuse local address
+ Broadcast, -- Enable datagram sockets to recv/send broadcasts
+ Send_Buffer, -- Set/get the maximum socket send buffer in bytes
+ Receive_Buffer, -- Set/get the maximum socket recv buffer in bytes
+ Linger, -- Shutdown wait for msg to be sent or timeout occur
+ Error, -- Get and clear the pending socket error
+ No_Delay, -- Do not delay send to coalesce data (TCP_NODELAY)
+ Add_Membership, -- Join a multicast group
+ Drop_Membership, -- Leave a multicast group
+ Multicast_If, -- Set default out interface for multicast packets
+ Multicast_TTL, -- Set the time-to-live of sent multicast packets
+ Multicast_Loop, -- Sent multicast packets are looped to local socket
+ Receive_Packet_Info, -- Receive low level packet info as ancillary data
+ Send_Timeout, -- Set timeout value for output
+ Receive_Timeout); -- Set timeout value for input
type Option_Type (Name : Option_Name := Keep_Alive) is record
case Name is
- when Keep_Alive |
- Reuse_Address |
- Broadcast |
- Linger |
- No_Delay |
- Multicast_Loop =>
+ when Keep_Alive |
+ Reuse_Address |
+ Broadcast |
+ Linger |
+ No_Delay |
+ Receive_Packet_Info |
+ Multicast_Loop =>
Enabled : Boolean;
case Name is
Multicast_Address : Inet_Addr_Type;
Local_Interface : Inet_Addr_Type;
+ when Multicast_If =>
+ Outgoing_If : Inet_Addr_Type;
+
when Multicast_TTL =>
Time_To_Live : Natural;
+ when Send_Timeout |
+ Receive_Timeout =>
+ Timeout : Timeval_Duration;
+
end case;
end record;
-- socket options in that they are not specific to sockets but are
-- available for any device.
- type Request_Name is (
- Non_Blocking_IO, -- Cause a caller not to wait on blocking operations.
+ type Request_Name is
+ (Non_Blocking_IO, -- Cause a caller not to wait on blocking operations
N_Bytes_To_Read); -- Return the number of bytes available to read
type Request_Type (Name : Request_Name := Non_Blocking_IO) is record
-- Socket_Stream).
Peek_At_Incoming_Data : constant Request_Flag_Type;
- -- This flag causes the receive operation to return data from the
- -- beginning of the receive queue without removing that data from the
- -- queue. A subsequent receive call will return the same data.
+ -- This flag causes the receive operation to return data from the beginning
+ -- of the receive queue without removing that data from the queue. A
+ -- subsequent receive call will return the same data.
Wait_For_A_Full_Reception : constant Request_Flag_Type;
-- This flag requests that the operation block until the full request is
-- is filled in with the address of the connection. Raises Socket_Error on
-- error.
+ procedure Accept_Socket
+ (Server : Socket_Type;
+ Socket : out Socket_Type;
+ Address : out Sock_Addr_Type;
+ Timeout : Selector_Duration;
+ Selector : access Selector_Type := null;
+ Status : out Selector_Status);
+ -- Accept a new connection on Server using Accept_Socket, waiting no longer
+ -- than the given timeout duration. Status is set to indicate whether the
+ -- operation completed successfully, timed out, or was aborted. If Selector
+ -- is not null, the designated selector is used to wait for the socket to
+ -- become available, else a private selector object is created by this
+ -- procedure and destroyed before it returns.
+
procedure Bind_Socket
(Socket : Socket_Type;
Address : Sock_Addr_Type);
procedure Connect_Socket
(Socket : Socket_Type;
- Server : in out Sock_Addr_Type);
- -- Make a connection to another socket which has the address of
- -- Server. Raises Socket_Error on error.
+ Server : Sock_Addr_Type);
+ -- Make a connection to another socket which has the address of Server.
+ -- Raises Socket_Error on error.
+
+ procedure Connect_Socket
+ (Socket : Socket_Type;
+ Server : Sock_Addr_Type;
+ Timeout : Selector_Duration;
+ Selector : access Selector_Type := null;
+ Status : out Selector_Status);
+ -- Connect Socket to the given Server address using Connect_Socket, waiting
+ -- no longer than the given timeout duration. Status is set to indicate
+ -- whether the operation completed successfully, timed out, or was aborted.
+ -- If Selector is not null, the designated selector is used to wait for the
+ -- socket to become available, else a private selector object is created
+ -- by this procedure and destroyed before it returns.
procedure Control_Socket
(Socket : Socket_Type;
Request : in out Request_Type);
-- Obtain or set parameter values that control the socket. This control
- -- differs from the socket options in that they are not specific to
- -- sockets but are available for any device.
+ -- differs from the socket options in that they are not specific to sockets
+ -- but are available for any device.
function Get_Peer_Name (Socket : Socket_Type) return Sock_Addr_Type;
-- Return the peer or remote socket address of a socket. Raise
function Get_Socket_Name (Socket : Socket_Type) return Sock_Addr_Type;
-- Return the local or current socket address of a socket. Return
- -- No_Sock_Addr on error (for instance, socket closed or not locally
- -- bound).
+ -- No_Sock_Addr on error (e.g. socket closed or not locally bound).
function Get_Socket_Option
(Socket : Socket_Type;
Level : Level_Type := Socket_Level;
Name : Option_Name) return Option_Type;
- -- Get the options associated with a socket. Raises Socket_Error
- -- on error.
+ -- Get the options associated with a socket. Raises Socket_Error on error
procedure Listen_Socket
(Socket : Socket_Type;
- Length : Positive := 15);
+ Length : Natural := 15);
-- To accept connections, a socket is first created with Create_Socket,
-- a willingness to accept incoming connections and a queue Length for
-- incoming connections are specified. Raise Socket_Error on error.
+ -- The queue length of 15 is an example value that should be appropriate
+ -- in usual cases. It can be adjusted according to each application's
+ -- particular requirements.
procedure Receive_Socket
(Socket : Socket_Type;
Flags : Request_Flag_Type := No_Request_Flag);
-- Receive message from Socket. Last is the index value such that Item
-- (Last) is the last character assigned. Note that Last is set to
- -- Item'First - 1 when the socket has been closed by peer. This is not an
- -- error and no exception is raised. Flags allows to control the
- -- reception. Raise Socket_Error on error.
+ -- Item'First - 1 when the socket has been closed by peer. This is not
+ -- an error, and no exception is raised in this case unless Item'First
+ -- is Stream_Element_Offset'First, in which case Constraint_Error is
+ -- raised. Flags allows to control the reception. Raise Socket_Error on
+ -- error.
procedure Receive_Socket
(Socket : Socket_Type;
procedure Receive_Vector
(Socket : Socket_Type;
Vector : Vector_Type;
- Count : out Ada.Streams.Stream_Element_Count);
+ Count : out Ada.Streams.Stream_Element_Count;
+ Flags : Request_Flag_Type := No_Request_Flag);
-- Receive data from a socket and scatter it into the set of vector
-- elements Vector. Count is set to the count of received stream elements.
+ -- Flags allow control over reception.
function Resolve_Exception
(Occurrence : Ada.Exceptions.Exception_Occurrence) return Error_Type;
(Socket : Socket_Type;
Item : Ada.Streams.Stream_Element_Array;
Last : out Ada.Streams.Stream_Element_Offset;
+ To : access Sock_Addr_Type;
Flags : Request_Flag_Type := No_Request_Flag);
- -- Transmit a message to another socket. Note that Last is set to
- -- Item'First-1 when socket has been closed by peer. This is not
- -- considered an error and no exception is raised. Flags allows to control
- -- the transmission. Raises Socket_Error on any other error condition.
+ pragma Inline (Send_Socket);
+ -- Transmit a message over a socket. For a datagram socket, the address
+ -- is given by To.all. For a stream socket, To must be null. Last
+ -- is the index value such that Item (Last) is the last character
+ -- sent. Note that Last is set to Item'First - 1 if the socket has been
+ -- closed by the peer (unless Item'First is Stream_Element_Offset'First,
+ -- in which case Constraint_Error is raised instead). This is not an error,
+ -- and Socket_Error is not raised in that case. Flags allows control of the
+ -- transmission. Raises exception Socket_Error on error. Note: this
+ -- subprogram is inlined because it is also used to implement the two
+ -- variants below.
+
+ procedure Send_Socket
+ (Socket : Socket_Type;
+ Item : Ada.Streams.Stream_Element_Array;
+ Last : out Ada.Streams.Stream_Element_Offset;
+ Flags : Request_Flag_Type := No_Request_Flag);
+ -- Transmit a message over a socket. Upon return, Last is set to the index
+ -- within Item of the last element transmitted. Flags allows to control
+ -- the transmission. Raises Socket_Error on any detected error condition.
procedure Send_Socket
(Socket : Socket_Type;
Last : out Ada.Streams.Stream_Element_Offset;
To : Sock_Addr_Type;
Flags : Request_Flag_Type := No_Request_Flag);
- -- Transmit a message to another socket. The address is given by To. Flags
- -- allows to control the transmission. Raises Socket_Error on error.
+ -- Transmit a message over a datagram socket. The destination address is
+ -- To. Flags allows to control the transmission. Raises Socket_Error on
+ -- error.
procedure Send_Vector
(Socket : Socket_Type;
Vector : Vector_Type;
- Count : out Ada.Streams.Stream_Element_Count);
+ Count : out Ada.Streams.Stream_Element_Count;
+ Flags : Request_Flag_Type := No_Request_Flag);
-- Transmit data gathered from the set of vector elements Vector to a
- -- socket. Count is set to the count of transmitted stream elements.
+ -- socket. Count is set to the count of transmitted stream elements. Flags
+ -- allow control over transmission.
procedure Set_Socket_Option
(Socket : Socket_Type;
procedure Shutdown_Socket
(Socket : Socket_Type;
How : Shutmode_Type := Shut_Read_Write);
- -- Shutdown a connected socket. If How is Shut_Read, further receives will
- -- be disallowed. If How is Shut_Write, further sends will be disallowed.
- -- If how is Shut_Read_Write, further sends and receives will be
- -- disallowed.
+ -- Shutdown a connected socket. If How is Shut_Read further receives will
+ -- be disallowed. If How is Shut_Write further sends will be disallowed.
+ -- If How is Shut_Read_Write further sends and receives will be disallowed.
type Stream_Access is access all Ada.Streams.Root_Stream_Type'Class;
-- Same interface as Ada.Streams.Stream_IO
- function Stream
- (Socket : Socket_Type) return Stream_Access;
- -- Create a stream associated with a stream-based socket that is
- -- already connected.
+ function Stream (Socket : Socket_Type) return Stream_Access;
+ -- Create a stream associated with an already connected stream-based socket
function Stream
(Socket : Socket_Type;
Send_To : Sock_Addr_Type) return Stream_Access;
- -- Create a stream associated with a datagram-based socket that is already
- -- bound. Send_To is the socket address to which messages are being sent.
+ -- Create a stream associated with an already bound datagram-based socket.
+ -- Send_To is the destination address to which messages are being sent.
function Get_Address
- (Stream : Stream_Access) return Sock_Addr_Type;
+ (Stream : not null Stream_Access) return Sock_Addr_Type;
-- Return the socket address from which the last message was received
procedure Free is new Ada.Unchecked_Deallocation
(Ada.Streams.Root_Stream_Type'Class, Stream_Access);
- -- Destroy a stream created by one of the Stream functions above,
- -- releasing the corresponding resources. The user is responsible for
- -- calling this subprogram when the stream is not needed anymore.
+ -- Destroy a stream created by one of the Stream functions above, releasing
+ -- the corresponding resources. The user is responsible for calling this
+ -- subprogram when the stream is not needed anymore.
type Socket_Set_Type is limited private;
-- This type allows to manipulate sets of sockets. It allows to wait for
- -- events on multiple endpoints at one time. This is an access type on a
- -- system dependent structure. To avoid memory leaks it is highly
- -- recommended to clean the access value with procedure Empty.
+ -- events on multiple endpoints at one time. This type has default
+ -- initialization, and the default value is the empty set.
+ --
+ -- Note: This type used to contain a pointer to dynamically allocated
+ -- storage, but this is not the case anymore, and no special precautions
+ -- are required to avoid memory leaks.
procedure Clear (Item : in out Socket_Set_Type; Socket : Socket_Type);
-- Remove Socket from Item
- procedure Copy (Source : Socket_Set_Type; Target : in out Socket_Set_Type);
+ procedure Copy (Source : Socket_Set_Type; Target : out Socket_Set_Type);
-- Copy Source into Target as Socket_Set_Type is limited private
- procedure Empty (Item : in out Socket_Set_Type);
- -- Remove all Sockets from Item and deallocate internal data
+ procedure Empty (Item : out Socket_Set_Type);
+ -- Remove all Sockets from Item
procedure Get (Item : in out Socket_Set_Type; Socket : out Socket_Type);
-- Extract a Socket from socket set Item. Socket is set to
-- No_Socket when the set is empty.
- function Is_Empty
- (Item : Socket_Set_Type) return Boolean;
+ function Is_Empty (Item : Socket_Set_Type) return Boolean;
-- Return True iff Item is empty
function Is_Set
procedure Set (Item : in out Socket_Set_Type; Socket : Socket_Type);
-- Insert Socket into Item
+ function Image (Item : Socket_Set_Type) return String;
+ -- Return a printable image of Item, for debugging purposes
+
-- The select(2) system call waits for events to occur on any of a set of
-- file descriptors. Usually, three independent sets of descriptors are
-- watched (read, write and exception). A timeout gives an upper bound
-- can block the full process (not just the calling thread).
--
-- Check_Selector provides the very same behaviour. The only difference is
- -- that it does not watch for exception events. Note that on some
- -- platforms it is kept process blocking on purpose. The timeout parameter
- -- allows the user to have the behaviour he wants. Abort_Selector allows
- -- to abort safely a Check_Selector that is blocked forever. A special
- -- file descriptor is opened by Create_Selector and included in each call
- -- to Check_Selector. Abort_Selector causes an event to occur on this
- -- descriptor in order to unblock Check_Selector. The user must call
- -- Close_Selector to discard this special file. A reason to abort a select
- -- operation is typically to add a socket in one of the socket sets when
- -- the timeout is set to forever.
-
- type Selector_Type is limited private;
- type Selector_Access is access all Selector_Type;
-
- -- Selector_Duration is a subtype of Standard.Duration because the full
- -- range of Standard.Duration cannot be represented in the equivalent C
- -- structure. Moreover, negative values are not allowed to avoid system
- -- incompatibilities.
-
- Immediate : constant := 0.0;
- Forever : constant := Duration (Integer'Last) * 1.0;
-
- subtype Selector_Duration is Duration range Immediate .. Forever;
+ -- that it does not watch for exception events. Note that on some platforms
+ -- it is kept process blocking on purpose. The timeout parameter allows the
+ -- user to have the behaviour he wants. Abort_Selector allows to safely
+ -- abort a blocked Check_Selector call. A special socket is opened by
+ -- Create_Selector and included in each call to Check_Selector.
+ --
+ -- Abort_Selector causes an event to occur on this descriptor in order to
+ -- unblock Check_Selector. Note that each call to Abort_Selector will cause
+ -- exactly one call to Check_Selector to return with Aborted status. The
+ -- special socket created by Create_Selector is closed when Close_Selector
+ -- is called.
+ --
+ -- A typical case where it is useful to abort a Check_Selector operation is
+ -- the situation where a change to the monitored sockets set must be made.
procedure Create_Selector (Selector : out Selector_Type);
- -- Create a new selector
+ -- Initialize (open) a new selector
procedure Close_Selector (Selector : in out Selector_Type);
- -- Close Selector and all internal descriptors associated
-
- type Selector_Status is (Completed, Expired, Aborted);
+ -- Close Selector and all internal descriptors associated; deallocate any
+ -- associated resources. This subprogram may be called only when there is
+ -- no other task still using Selector (i.e. still executing Check_Selector
+ -- or Abort_Selector on this Selector). Has no effect if Selector is
+ -- already closed.
procedure Check_Selector
- (Selector : in out Selector_Type;
+ (Selector : Selector_Type;
R_Socket_Set : in out Socket_Set_Type;
W_Socket_Set : in out Socket_Set_Type;
Status : out Selector_Status;
-- cases Status is set to Completed and sockets that are ready are set in
-- R_Socket_Set or W_Socket_Set. Status is set to Expired if no socket was
-- ready after a Timeout expiration. Status is set to Aborted if an abort
- -- signal has been received while checking socket status. As this
- -- procedure returns when Timeout occurs, it is a design choice to keep
- -- this procedure process blocking. Note that a Timeout of 0.0 returns
- -- immediately. Also note that two different Socket_Set_Type objects must
- -- be passed as R_Socket_Set and W_Socket_Set (even if they denote the
- -- same set of Sockets), or some event may be lost.
- -- Socket_Error is raised when the select(2) system call returns an
- -- error condition, or when a read error occurs on the signalling socket
- -- used for the implementation of Abort_Selector.
+ -- signal has been received while checking socket status.
+ --
+ -- Note that two different Socket_Set_Type objects must be passed as
+ -- R_Socket_Set and W_Socket_Set (even if they denote the same set of
+ -- Sockets), or some event may be lost.
+ --
+ -- Socket_Error is raised when the select(2) system call returns an error
+ -- condition, or when a read error occurs on the signalling socket used for
+ -- the implementation of Abort_Selector.
procedure Check_Selector
- (Selector : in out Selector_Type;
+ (Selector : Selector_Type;
R_Socket_Set : in out Socket_Set_Type;
W_Socket_Set : in out Socket_Set_Type;
E_Socket_Set : in out Socket_Set_Type;
Status : out Selector_Status;
Timeout : Selector_Duration := Forever);
- -- This refined version of Check_Selector allows to watch for exception
- -- events (that is notifications of out-of-band transmission and
- -- reception). As above, all of R_Socket_Set, W_Socket_Set and
- -- E_Socket_Set must be different objects.
+ -- This refined version of Check_Selector allows watching for exception
+ -- events (i.e. notifications of out-of-band transmission and reception).
+ -- As above, all of R_Socket_Set, W_Socket_Set and E_Socket_Set must be
+ -- different objects.
procedure Abort_Selector (Selector : Selector_Type);
- -- Send an abort signal to the selector
+ -- Send an abort signal to the selector. The Selector may not be the
+ -- Null_Selector.
+
+ type Fd_Set is private;
+ -- ??? This type must not be used directly, it needs to be visible because
+ -- it is used in the visible part of GNAT.Sockets.Thin_Common. This is
+ -- really an inversion of abstraction. The private part of GNAT.Sockets
+ -- needs to have visibility on this type, but since Thin_Common is a child
+ -- of Sockets, the type can't be declared there. The correct fix would
+ -- be to move the thin sockets binding outside of GNAT.Sockets altogether,
+ -- e.g. by renaming it to GNAT.Sockets_Thin.
private
type Socket_Type is new Integer;
No_Socket : constant Socket_Type := -1;
- type Selector_Type is limited record
- R_Sig_Socket : Socket_Type;
- W_Sig_Socket : Socket_Type;
+ -- A selector is either a null selector, which is always "open" and can
+ -- never be aborted, or a regular selector, which is created "closed",
+ -- becomes "open" when Create_Selector is called, and "closed" again when
+ -- Close_Selector is called.
+
+ type Selector_Type (Is_Null : Boolean := False) is limited record
+ case Is_Null is
+ when True =>
+ null;
+
+ when False =>
+ R_Sig_Socket : Socket_Type := No_Socket;
+ W_Sig_Socket : Socket_Type := No_Socket;
+ -- Signalling sockets used to abort a select operation
+
+ end case;
end record;
pragma Volatile (Selector_Type);
- -- The two signalling sockets are used to abort a select operation
+ Null_Selector : constant Selector_Type := (Is_Null => True);
+
+ type Fd_Set is
+ new System.Storage_Elements.Storage_Array (1 .. SOSC.SIZEOF_fd_set);
+ for Fd_Set'Alignment use Interfaces.C.long'Alignment;
+ -- Set conservative alignment so that our Fd_Sets are always adequately
+ -- aligned for the underlying data type (which is implementation defined
+ -- and may be an array of C long integers).
- subtype Socket_Set_Access is System.Address;
- No_Socket_Set : constant Socket_Set_Access := System.Null_Address;
+ type Fd_Set_Access is access all Fd_Set;
+ pragma Convention (C, Fd_Set_Access);
+ No_Fd_Set_Access : constant Fd_Set_Access := null;
type Socket_Set_Type is record
- Last : Socket_Type := No_Socket;
- Set : Socket_Set_Access := No_Socket_Set;
+ Last : Socket_Type := No_Socket;
+ -- Highest socket in set. Last = No_Socket denotes an empty set (which
+ -- is the default initial value).
+
+ Set : aliased Fd_Set;
+ -- Underlying socket set. Note that the contents of this component is
+ -- undefined if Last = No_Socket.
end record;
subtype Inet_Addr_Comp_Type is Natural range 0 .. 255;
(Family_Inet, (others => 0));
Broadcast_Inet_Addr : constant Inet_Addr_Type :=
(Family_Inet, (others => 255));
+ Loopback_Inet_Addr : constant Inet_Addr_Type :=
+ (Family_Inet, (127, 0, 0, 1));
+
+ Unspecified_Group_Inet_Addr : constant Inet_Addr_Type :=
+ (Family_Inet, (224, 0, 0, 0));
+ All_Hosts_Group_Inet_Addr : constant Inet_Addr_Type :=
+ (Family_Inet, (224, 0, 0, 1));
+ All_Routers_Group_Inet_Addr : constant Inet_Addr_Type :=
+ (Family_Inet, (224, 0, 0, 2));
No_Sock_Addr : constant Sock_Addr_Type := (Family_Inet, No_Inet_Addr, 0);
subtype Name_Index is Natural range 1 .. Max_Name_Length;
- type Name_Type
- (Length : Name_Index := Max_Name_Length)
- is record
+ type Name_Type (Length : Name_Index := Max_Name_Length) is record
Name : String (1 .. Length);
end record;
-- We need fixed strings to avoid access types in host entry type
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