------------------------------------------------------------------------------ -- -- -- GNAT COMPILER COMPONENTS -- -- -- -- G N A T . S O C K E T S -- -- -- -- S p e c -- -- -- -- Copyright (C) 2001-2002 Ada Core Technologies, Inc. -- -- -- -- 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- -- -- ware Foundation; either version 2, or (at your option) any later ver- -- -- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- -- for more details. You should have received a copy of the GNU General -- -- Public License distributed with GNAT; see file COPYING. If not, write -- -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, -- -- MA 02111-1307, USA. -- -- -- -- As a special exception, if other files instantiate generics from this -- -- unit, or you link this unit with other files to produce an executable, -- -- this unit does not by itself cause the resulting executable to be -- -- covered by the GNU General Public License. This exception does not -- -- however invalidate any other reasons why the executable file might be -- -- covered by the GNU Public License. -- -- -- -- GNAT is maintained by Ada Core Technologies Inc (http://www.gnat.com). -- -- -- ------------------------------------------------------------------------------ -- This package provides an interface to the sockets communication facility -- provided on many operating systems. Currently this is implemented on all -- native GNAT ports except for VMS. It is not yet implemented on the Lynx -- cross-ports. -- Another restriction is that there is no multicast support under Windows -- or under any system on which the multicast support is not available or -- installed. with Ada.Exceptions; with Ada.Streams; package GNAT.Sockets is -- Sockets are designed to provide a consistent communication facility -- between applications. This package provides an Ada-like intrerface -- similar to that proposed as part of the BSD socket layer. This is a -- system independent thick binding. -- Here is a typical example of what you can do: -- with GNAT.Sockets; use GNAT.Sockets; -- -- with Ada.Text_IO; -- with Ada.Exceptions; use Ada.Exceptions; -- -- procedure PingPong is -- -- Group : constant String := "239.255.128.128"; -- -- Multicast groupe: administratively scoped IP address -- -- task Pong is -- entry Start; -- entry Stop; -- end Pong; -- -- task body Pong is -- Address : Sock_Addr_Type; -- Server : Socket_Type; -- Socket : Socket_Type; -- Channel : Stream_Access; -- -- begin -- accept Start; -- -- -- Get an Internet address of a host (here the local host name). -- -- Note that a host can have several addresses. Here we get -- -- the first one which is supposed to be the official one. -- -- Address.Addr := Addresses (Get_Host_By_Name (Host_Name), 1); -- -- -- Get a socket address that is an Internet address and a port -- -- Address.Port := 5432; -- -- -- The first step is to create a socket. Once created, this -- -- socket must be associated to with an address. Usually only -- -- a server (Pong here) needs to bind an address explicitly. -- -- Most of the time clients can skip this step because the -- -- socket routines will bind an arbitrary address to an unbound -- -- socket. -- -- Create_Socket (Server); -- -- -- Allow reuse of local addresses. -- -- Set_Socket_Option -- (Server, -- Socket_Level, -- (Reuse_Address, True)); -- -- Bind_Socket (Server, Address); -- -- -- A server marks a socket as willing to receive connect events. -- -- Listen_Socket (Server); -- -- -- Once a server calls Listen_Socket, incoming connects events -- -- can be accepted. The returned Socket is a new socket that -- -- represents the server side of the connection. Server remains -- -- available to receive further connections. -- -- Accept_Socket (Server, Socket, Address); -- -- -- Return a stream associated to the connected socket. -- -- Channel := Stream (Socket); -- -- -- Force Pong to block -- -- delay 0.2; -- -- -- Receive and print message from client Ping. -- -- declare -- Message : String := String'Input (Channel); -- -- begin -- Ada.Text_IO.Put_Line (Message); -- -- -- Send same message to server Pong. -- -- String'Output (Channel, Message); -- end; -- -- Close_Socket (Server); -- Close_Socket (Socket); -- -- -- Part of the multicast example -- -- -- Create a datagram socket to send connectionless, unreliable -- -- messages of a fixed maximum length. -- -- Create_Socket (Socket, Family_Inet, Socket_Datagram); -- -- -- Allow reuse of local addresses. -- -- Set_Socket_Option -- (Socket, -- 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 -- -- to another and when its value reaches 0 the packet is -- -- dropped. Default is 1. -- -- Set_Socket_Option -- (Socket, -- IP_Protocol_For_IP_Level, -- (Multicast_TTL, 1)); -- -- -- Want the data you send to be looped back to your host. -- -- Set_Socket_Option -- (Socket, -- IP_Protocol_For_IP_Level, -- (Multicast_Loop, True)); -- -- -- If this socket is intended to receive messages, bind it to a -- -- given socket address. -- -- Address.Addr := Any_Inet_Addr; -- Address.Port := 55505; -- -- Bind_Socket (Socket, Address); -- -- -- If this socket is intended to send messages, provide the -- -- receiver socket address. -- -- Address.Addr := Inet_Addr (Group); -- Address.Port := 55506; -- -- Channel := Stream (Socket, Address); -- -- -- Receive and print message from client Ping. -- -- declare -- Message : String := String'Input (Channel); -- -- begin -- -- -- Get the address of the sender. -- -- Address := Get_Address (Channel); -- Ada.Text_IO.Put_Line (Message & " from " & Image (Address)); -- -- -- Send same message to server Pong. -- -- String'Output (Channel, Message); -- end; -- -- Close_Socket (Socket); -- -- accept Stop; -- -- exception when E : others => -- Ada.Text_IO.Put_Line -- (Exception_Name (E) & ": " & Exception_Message (E)); -- end Pong; -- -- task Ping is -- entry Start; -- entry Stop; -- end Ping; -- -- task body Ping is -- Address : Sock_Addr_Type; -- Socket : Socket_Type; -- Channel : Stream_Access; -- -- begin -- accept Start; -- -- -- See comments in Ping section for the first steps. -- -- Address.Addr := Addresses (Get_Host_By_Name (Host_Name), 1); -- Address.Port := 5432; -- Create_Socket (Socket); -- -- Set_Socket_Option -- (Socket, -- Socket_Level, -- (Reuse_Address, True)); -- -- -- Force Pong to block -- -- delay 0.2; -- -- -- If the client's socket is not bound, Connect_Socket will -- -- bind to an unused address. The client uses Connect_Socket to -- -- create a logical connection between the client's socket and -- -- a server's socket returned by Accept_Socket. -- -- Connect_Socket (Socket, Address); -- -- Channel := Stream (Socket); -- -- -- Send message to server Pong. -- -- String'Output (Channel, "Hello world"); -- -- -- Force Ping to block -- -- delay 0.2; -- -- -- Receive and print message from server Pong. -- -- Ada.Text_IO.Put_Line (String'Input (Channel)); -- Close_Socket (Socket); -- -- -- Part of multicast example. Code similar to Pong's one. -- -- Create_Socket (Socket, Family_Inet, Socket_Datagram); -- -- Set_Socket_Option -- (Socket, -- Socket_Level, -- (Reuse_Address, True)); -- -- 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 -- (Socket, -- IP_Protocol_For_IP_Level, -- (Multicast_Loop, True)); -- -- Address.Addr := Any_Inet_Addr; -- Address.Port := 55506; -- -- Bind_Socket (Socket, Address); -- -- Address.Addr := Inet_Addr (Group); -- Address.Port := 55505; -- -- Channel := Stream (Socket, Address); -- -- -- Send message to server Pong. -- -- String'Output (Channel, "Hello world"); -- -- -- Receive and print message from server Pong. -- -- declare -- Message : String := String'Input (Channel); -- -- begin -- Address := Get_Address (Channel); -- Ada.Text_IO.Put_Line (Message & " from " & Image (Address)); -- end; -- -- Close_Socket (Socket); -- -- accept Stop; -- -- exception when E : others => -- Ada.Text_IO.Put_Line -- (Exception_Name (E) & ": " & Exception_Message (E)); -- 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); -- Ping.Start; -- Pong.Start; -- Ping.Stop; -- Pong.Stop; -- Finalize; -- end PingPong; procedure Initialize (Process_Blocking_IO : Boolean := False); -- Initialize must be called before using any socket routines. If -- the thread library provides process blocking IO - basically -- with FSU threads - GNAT.Sockets should be initialized with a -- value of True to simulate thread blocking IO. Further calls to -- Initialize will be ignored. procedure Finalize; -- After Finalize is called it is not possible to use any routines -- exported in by this package. This procedure is idempotent. type Socket_Type is private; -- Sockets are used to implement a reliable bi-directional -- point-to-point, stream-based connections between -- hosts. No_Socket provides a special value to denote -- uninitialized sockets. No_Socket : constant Socket_Type; 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 the error code. function Image (Socket : Socket_Type) return String; -- Return a printable string for Socket function To_C (Socket : Socket_Type) return Integer; -- Return a file descriptor to be used by external subprograms -- especially the C functions that are not yet interfaced in this -- package. 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. type Mode_Type is (Socket_Stream, Socket_Datagram); -- Stream sockets provide connection-oriented byte -- streams. Datagram sockets support unreliable connectionless -- message based communication. type Shutmode_Type is (Shut_Read, Shut_Write, Shut_Read_Write); -- When a process closes a socket, the policy is to retain any -- data queued until either a delivery or a timeout expiration (in -- this case, the data are discarded). A finer control is -- available through shutdown. With Shut_Read, no more data can be -- received from the socket. With_Write, no 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. Any_Port : constant Port_Type; No_Port : constant Port_Type; 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_Address 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; type Sock_Addr_Type (Family : Family_Type := Family_Inet) is record Addr : Inet_Addr_Type (Family); Port : Port_Type; end record; -- Socket addresses fully define a socket connection with a -- protocol family, an Internet address and a port. No_Sock_Addr -- provides a special value for uninitialized socket addresses. No_Sock_Addr : constant Sock_Addr_Type; function Image (Value : Inet_Addr_Type) return String; -- Return an image of an Internet address. IPv4 notation consists -- in 4 octets in decimal format separated by dots. IPv6 notation -- consists in 16 octets in hexadecimal format separated by -- colons (and possibly dots). function Image (Value : Sock_Addr_Type) return String; -- Return inet address image and port image separated by a colon. function Inet_Addr (Image : String) return Inet_Addr_Type; -- Convert address image from numbers-and-dots notation into an -- inet address. -- Host entries provide a complete information on a given host: -- the official name, an array of alternative names or aliases and -- array of network addresses. type Host_Entry_Type (Aliases_Length, Addresses_Length : Natural) is private; function Official_Name (E : Host_Entry_Type) return String; -- Return official name in host entry function Aliases_Length (E : Host_Entry_Type) return Natural; -- Return number of aliases in host entry function Addresses_Length (E : Host_Entry_Type) return Natural; -- Return number of addresses in host entry function Aliases (E : Host_Entry_Type; N : Positive := 1) return String; -- Return N'th aliases in host entry. The first index is 1. function Addresses (E : Host_Entry_Type; N : Positive := 1) return Inet_Addr_Type; -- Return N'th addresses in host entry. The first index is 1. 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. function Get_Host_By_Address (Address : Inet_Addr_Type; Family : Family_Type := Family_Inet) return Host_Entry_Type; -- Return host entry structure for the given inet address function Get_Host_By_Name (Name : String) return Host_Entry_Type; -- Return host entry structure for the given host name function Host_Name return String; -- Return the name of the current host -- 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. type Error_Type is (Permission_Denied, Address_Already_In_Use, Cannot_Assign_Requested_Address, Address_Family_Not_Supported_By_Protocol, Operation_Already_In_Progress, Bad_File_Descriptor, Connection_Refused, Bad_Address, Operation_Now_In_Progress, Interrupted_System_Call, Invalid_Argument, Input_Output_Error, Transport_Endpoint_Already_Connected, Message_Too_Long, Network_Is_Unreachable, No_Buffer_Space_Available, Protocol_Not_Available, Transport_Endpoint_Not_Connected, Operation_Not_Supported, Protocol_Not_Supported, Socket_Type_Not_Supported, Connection_Timed_Out, Resource_Temporarily_Unavailable, Unknown_Host, Host_Name_Lookup_Failure, No_Address_Associated_With_Name, Unknown_Server_Error, Cannot_Resolve_Error); -- Get_Socket_Options and Set_Socket_Options manipulate options -- associated 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); -- 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, -- Indicates the time-to-live of sent multicast packets Multicast_Loop); -- Sent multicast packets are looped to the local socket type Option_Type (Name : Option_Name := Keep_Alive) is record case Name is when Keep_Alive | Reuse_Address | Broadcast | Linger | No_Delay | Multicast_Loop => Enabled : Boolean; case Name is when Linger => Seconds : Natural; when others => null; end case; when Send_Buffer | Receive_Buffer => Size : Natural; when Error => Error : Error_Type; when Add_Membership | Drop_Membership => Multiaddr : Inet_Addr_Type; Interface : Inet_Addr_Type; when Multicast_TTL => Time_To_Live : Natural; end case; end record; -- There are several controls available to manipulate -- sockets. Each option has a name and several values available. -- These controls differ from the 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. N_Bytes_To_Read); -- Return the number of bytes available to read type Request_Type (Name : Request_Name := Non_Blocking_IO) is record case Name is when Non_Blocking_IO => Enabled : Boolean; when N_Bytes_To_Read => Size : Natural; end case; end record; procedure Create_Socket (Socket : out Socket_Type; Family : Family_Type := Family_Inet; Mode : Mode_Type := Socket_Stream); -- Create an endpoint for communication. Raise Socket_Error on error. procedure Accept_Socket (Server : Socket_Type; Socket : out Socket_Type; Address : out Sock_Addr_Type); -- Extract the first connection request on the queue of pending -- connections, creates a new connected socket with mostly the -- same properties as Server, and allocates a new socket. The -- returned Address is filled in with the address of the -- connection. Raise Socket_Error on error. procedure Bind_Socket (Socket : Socket_Type; Address : Sock_Addr_Type); -- Once a socket is created, assign a local address to it. Raise -- Socket_Error on error. procedure Close_Socket (Socket : Socket_Type); -- Close a socket and more specifically a non-connected socket. procedure Connect_Socket (Socket : Socket_Type; Server : in out Sock_Addr_Type); -- Make a connection to another socket which has the address of -- Server. Raise Socket_Error on error. 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 avaiable 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 -- Socket_Error on error. function Get_Socket_Name (Socket : Socket_Type) return Sock_Addr_Type; -- Return the local or current socket address of a socket. Raise -- Socket_Error on error. 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. Raise Socket_Error on -- error. procedure Listen_Socket (Socket : Socket_Type; Length : Positive := 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. procedure Receive_Socket (Socket : Socket_Type; Item : out Ada.Streams.Stream_Element_Array; Last : out Ada.Streams.Stream_Element_Offset); -- 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. Raise -- Socket_Error on error. procedure Receive_Socket (Socket : Socket_Type; Item : out Ada.Streams.Stream_Element_Array; Last : out Ada.Streams.Stream_Element_Offset; From : out Sock_Addr_Type); -- Receive message from Socket. If Socket is not -- connection-oriented, the source address From of the message is -- filled in. Last is the index value such that Item (Last) is the -- last character assigned. Raise Socket_Error on error. function Resolve_Exception (Occurrence : Ada.Exceptions.Exception_Occurrence) return Error_Type; -- When Socket_Error or Host_Error are raised, the exception -- message contains the error code between brackets and a string -- describing the error code. Resolve_Error extracts the error -- code from an exception message and translate it into an -- enumeration value. procedure Send_Socket (Socket : Socket_Type; Item : Ada.Streams.Stream_Element_Array; Last : out Ada.Streams.Stream_Element_Offset); -- Transmit a message to another socket. Note that Last is set to -- Item'First when socket has been closed by peer. This is not an -- error and no exception is raised. Raise Socket_Error on error; procedure Send_Socket (Socket : Socket_Type; Item : Ada.Streams.Stream_Element_Array; Last : out Ada.Streams.Stream_Element_Offset; To : Sock_Addr_Type); -- Transmit a message to another socket. The address is given by -- To. Raise Socket_Error on error; procedure Set_Socket_Option (Socket : Socket_Type; Level : Level_Type := Socket_Level; Option : Option_Type); -- Manipulate socket options. Raise Socket_Error on error. 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. 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; -- Associate a stream with a stream-based socket that is already -- connected. function Stream (Socket : Socket_Type; Send_To : Sock_Addr_Type) return Stream_Access; -- Associate a stream with a datagram-based socket that is already -- bound. Send_To is the socket address to which messages are -- being sent. function Get_Address (Stream : Stream_Access) return Sock_Addr_Type; -- Return the socket address from which the last message was -- received. type Socket_Set_Type is 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. procedure Clear (Item : in out Socket_Set_Type; Socket : Socket_Type); -- Remove Socket from Item procedure Set (Item : in out Socket_Set_Type; Socket : Socket_Type); -- Insert Socket into Item procedure Empty (Item : in out Socket_Set_Type); -- Remove all Sockets from Item and deallocate internal data function Is_Empty (Item : Socket_Set_Type) return Boolean; -- Return True if Item is empty function Is_Set (Item : Socket_Set_Type; Socket : Socket_Type) return Boolean; -- Return True if Socket is present in Item -- C select() waits for a number of file descriptors to change -- status. Usually, three independent sets of descriptors are -- watched (read, write and exception). A timeout gives an upper -- bound on the amount of time elapsed before select returns. -- This function blocks until an event occurs. On some platforms, -- C select can block the full process. -- -- 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 in 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. Forever : constant Duration; type Selector_Type is limited private; type Selector_Access is access all Selector_Type; procedure Create_Selector (Selector : out Selector_Type); -- Create 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); procedure Check_Selector (Selector : in out Selector_Type; R_Socket_Set : in out Socket_Set_Type; W_Socket_Set : in out Socket_Set_Type; Status : out Selector_Status; Timeout : Duration := Forever); -- Return when one Socket in R_Socket_Set has some data to be read -- or if one Socket in W_Socket_Set is ready to receive some -- data. In these 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 -- immediatly. procedure Abort_Selector (Selector : Selector_Type); -- Send an abort signal to the selector. private type Socket_Type is new Integer; No_Socket : constant Socket_Type := -1; Forever : constant Duration := Duration'Last; type Selector_Type is limited record R_Sig_Socket : Socket_Type; W_Sig_Socket : Socket_Type; In_Progress : Boolean := False; end record; -- The two signalling sockets are used to abort a select -- operation. type Socket_Set_Record; type Socket_Set_Type is access all Socket_Set_Record; subtype Inet_Addr_Comp_Type is Natural range 0 .. 255; -- Octet for Internet address type Inet_Addr_VN_Type is array (Natural range <>) of Inet_Addr_Comp_Type; subtype Inet_Addr_V4_Type is Inet_Addr_VN_Type (1 .. 4); subtype Inet_Addr_V6_Type is Inet_Addr_VN_Type (1 .. 16); type Inet_Addr_Type (Family : Family_Type := Family_Inet) is record case Family is when Family_Inet => Sin_V4 : Inet_Addr_V4_Type := (others => 0); when Family_Inet6 => Sin_V6 : Inet_Addr_V6_Type := (others => 0); end case; end record; Any_Port : constant Port_Type := 0; No_Port : constant Port_Type := 0; Any_Inet_Addr : constant Inet_Addr_Type := (Family_Inet, (others => 0)); No_Inet_Addr : constant Inet_Addr_Type := (Family_Inet, (others => 0)); No_Sock_Addr : constant Sock_Addr_Type := (Family_Inet, No_Inet_Addr, 0); Max_Host_Name_Length : constant := 64; -- The constant MAXHOSTNAMELEN is usually set to 64 subtype Host_Name_Index is Natural range 1 .. Max_Host_Name_Length; type Host_Name_Type (Length : Host_Name_Index := Max_Host_Name_Length) is record Name : String (1 .. Length); end record; -- We need fixed strings to avoid access types in host entry type type Host_Name_Array is array (Natural range <>) of Host_Name_Type; type Inet_Addr_Array is array (Natural range <>) of Inet_Addr_Type; type Host_Entry_Type (Aliases_Length, Addresses_Length : Natural) is record Official : Host_Name_Type; Aliases : Host_Name_Array (1 .. Aliases_Length); Addresses : Inet_Addr_Array (1 .. Addresses_Length); end record; end GNAT.Sockets;