net

This module implements a high-level cross-platform sockets interface. The procedures implemented in this module are primarily for blocking sockets. For asynchronous non-blocking sockets use the asyncnet module together with the asyncdispatch module.

The first thing you will always need to do in order to start using sockets, is to create a new instance of the Socket type using the newSocket procedure.

SSL

In order to use the SSL procedures defined in this module, you will need to compile your application with the -d:ssl flag.

Examples

Connecting to a server

After you create a socket with the newSocket procedure, you can easily connect it to a server running at a known hostname (or IP address) and port. To do so over TCP, use the example below.

var socket = newSocket()
socket.connect("google.com", Port(80))

UDP is a connectionless protocol, so UDP sockets don't have to explicitly call the connect procedure. They can simply start sending data immediately.

var socket = newSocket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)
socket.sendTo("192.168.0.1", Port(27960), "status\n")

Creating a server

After you create a socket with the newSocket procedure, you can create a TCP server by calling the bindAddr and listen procedures.

var socket = newSocket()
socket.bindAddr(Port(1234))
socket.listen()

You can then begin accepting connections using the accept procedure.

var client: Socket
var address = ""
while true:
  socket.acceptAddr(client, address)
  echo("Client connected from: ", address)

Types

SslError = object of Exception
  Source Edit
SslCVerifyMode = enum
  CVerifyNone, CVerifyPeer
  Source Edit
SslProtVersion = enum
  protSSLv2, protSSLv3, protTLSv1, protSSLv23
  Source Edit
SslContext = ref object
  context*: SslCtx
  referencedData: HashSet[int]
  extraInternal: SslContextExtraInternal
  Source Edit
SslAcceptResult = enum
  AcceptNoClient = 0, AcceptNoHandshake, AcceptSuccess
  Source Edit
SslHandshakeType = enum
  handshakeAsClient, handshakeAsServer
  Source Edit
SslClientGetPskFunc = proc (hint: string): tuple[identity: string, psk: string]
  Source Edit
SslServerGetPskFunc = proc (identity: string): string
  Source Edit
SocketImpl = object
  fd: SocketHandle
  isBuffered: bool
  buffer: array[0 .. BufferSize, char]
  currPos: int
  bufLen: int
  when defineSsl:
      isSsl: bool
      sslHandle: SslPtr
      sslContext: SslContext
      sslNoHandshake: bool
      sslHasPeekChar: bool
      sslPeekChar: char

  lastError: OSErrorCode       ## stores the last error on this socket
  domain: Domain
  sockType: SockType
  protocol: Protocol
socket type   Source Edit
Socket = ref SocketImpl
  Source Edit
SOBool = enum
  OptAcceptConn, OptBroadcast, OptDebug, OptDontRoute, OptKeepAlive, OptOOBInline,
  OptReuseAddr, OptReusePort, OptNoDelay
Boolean socket options.   Source Edit
ReadLineResult = enum
  ReadFullLine, ReadPartialLine, ReadDisconnected, ReadNone
result for readLineAsync   Source Edit
TimeoutError = object of Exception
  Source Edit
SocketFlag {...}{.pure.} = enum
  Peek, SafeDisconn            ## Ensures disconnection exceptions (ECONNRESET, EPIPE etc) are not thrown.
  Source Edit
IpAddressFamily {...}{.pure.} = enum
  IPv6,                       ## IPv6 address
  IPv4                        ## IPv4 address
Describes the type of an IP address   Source Edit
IpAddress = object
  case family*: IpAddressFamily ## the type of the IP address (IPv4 or IPv6)
  of IpAddressFamily.IPv6:
      address_v6*: array[0 .. 15, uint8] ## Contains the IP address in bytes in
                                    ## case of IPv6
    
  of IpAddressFamily.IPv4:
      address_v4*: array[0 .. 3, uint8] ## Contains the IP address in bytes in
                                   ## case of IPv4
    
  
stores an arbitrary IP address   Source Edit

Consts

BufferSize: int = 4000
size of a buffered socket's buffer   Source Edit
MaxLineLength = 1000000
  Source Edit

Procs

proc isDisconnectionError(flags: set[SocketFlag]; lastError: OSErrorCode): bool {...}{.
    raises: [], tags: [].}
Determines whether lastError is a disconnection error. Only does this if flags contains SafeDisconn.   Source Edit
proc toOSFlags(socketFlags: set[SocketFlag]): cint {...}{.raises: [], tags: [].}
Converts the flags into the underlying OS representation.   Source Edit
proc newSocket(fd: SocketHandle; domain: Domain = AF_INET;
              sockType: SockType = SOCK_STREAM; protocol: Protocol = IPPROTO_TCP;
              buffered = true): owned(Socket) {...}{.raises: [], tags: [].}
Creates a new socket as specified by the params.   Source Edit
proc newSocket(domain, sockType, protocol: cint; buffered = true): owned(Socket) {...}{.
    raises: [OSError], tags: [].}

Creates a new socket.

If an error occurs OSError will be raised.

  Source Edit
proc newSocket(domain: Domain = AF_INET; sockType: SockType = SOCK_STREAM;
              protocol: Protocol = IPPROTO_TCP; buffered = true): owned(Socket) {...}{.
    raises: [OSError], tags: [].}

Creates a new socket.

If an error occurs OSError will be raised.

  Source Edit
proc parseIpAddress(addressStr: string): IpAddress {...}{.raises: [ValueError], tags: [].}
Parses an IP address Raises ValueError on error   Source Edit
proc isIpAddress(addressStr: string): bool {...}{.tags: [], raises: [].}
Checks if a string is an IP address Returns true if it is, false otherwise   Source Edit
proc toSockAddr(address: IpAddress; port: Port; sa: var Sockaddr_storage;
               sl: var SockLen) {...}{.raises: [], tags: [].}
Converts IpAddress and Port to SockAddr and SockLen   Source Edit
proc fromSockAddr(sa: Sockaddr_storage | SockAddr | Sockaddr_in | Sockaddr_in6;
                 sl: SockLen; address: var IpAddress; port: var Port) {...}{.inline.}
Converts SockAddr and SockLen to IpAddress and Port. Raises ObjectConversionError in case of invalid sa and sl arguments.   Source Edit
proc raiseSSLError(s = "") {...}{.raises: [SslError, OSError], tags: [].}
Raises a new SSL error.   Source Edit
proc getExtraData(ctx: SslContext; index: int): RootRef {...}{.
    raises: [IndexError, SslError, OSError], tags: [].}
Retrieves arbitrary data stored inside SSLContext.   Source Edit
proc setExtraData(ctx: SslContext; index: int; data: RootRef) {...}{.
    raises: [IndexError, SslError, OSError], tags: [].}
Stores arbitrary data inside SSLContext. The unique index should be retrieved using getSslContextExtraDataIndex.   Source Edit
proc newContext(protVersion = protSSLv23; verifyMode = CVerifyPeer; certFile = "";
               keyFile = ""; cipherList = "ALL"): SslContext {...}{.
    raises: [Exception, SslError, OSError, IOError],
    tags: [RootEffect, ReadDirEffect].}

Creates an SSL context.

Protocol version specifies the protocol to use. SSLv2, SSLv3, TLSv1 are available with the addition of protSSLv23 which allows for compatibility with all of them.

There are currently only two options for verify mode; one is CVerifyNone and with it certificates will not be verified the other is CVerifyPeer and certificates will be verified for it, CVerifyPeer is the safest choice.

The last two parameters specify the certificate file path and the key file path, a server socket will most likely not work without these. Certificates can be generated using the following command: openssl req -x509 -nodes -days 365 -newkey rsa:1024 -keyout mycert.pem -out mycert.pem.

  Source Edit
proc destroyContext(ctx: SslContext) {...}{.raises: [IndexError, SslError, OSError],
                                    tags: [].}
Free memory referenced by SSLContext.   Source Edit
proc pskIdentityHint=(ctx: SslContext; hint: string) {...}{.raises: [SslError, OSError],
    tags: [].}

Sets the identity hint passed to server.

Only used in PSK ciphersuites.

  Source Edit
proc clientGetPskFunc(ctx: SslContext): SslClientGetPskFunc {...}{.raises: [], tags: [].}
  Source Edit
proc clientGetPskFunc=(ctx: SslContext; fun: SslClientGetPskFunc) {...}{.
    raises: [Exception], tags: [RootEffect].}

Sets function that returns the client identity and the PSK based on identity hint from the server.

Only used in PSK ciphersuites.

  Source Edit
proc serverGetPskFunc(ctx: SslContext): SslServerGetPskFunc {...}{.raises: [], tags: [].}
  Source Edit
proc serverGetPskFunc=(ctx: SslContext; fun: SslServerGetPskFunc) {...}{.
    raises: [Exception], tags: [RootEffect].}

Sets function that returns PSK based on the client identity.

Only used in PSK ciphersuites.

  Source Edit
proc getPskIdentity(socket: Socket): string {...}{.raises: [], tags: [].}
Gets the PSK identity provided by the client.   Source Edit
proc wrapSocket(ctx: SslContext; socket: Socket) {...}{.raises: [SslError, OSError], tags: [].}

Wraps a socket in an SSL context. This function effectively turns socket into an SSL socket.

This must be called on an unconnected socket; an SSL session will be started when the socket is connected.

Disclaimer: This code is not well tested, may be very unsafe and prone to security vulnerabilities.

  Source Edit
proc wrapConnectedSocket(ctx: SslContext; socket: Socket;
                        handshake: SslHandshakeType; hostname: string = "") {...}{.
    raises: [SslError, OSError, Exception], tags: [RootEffect].}

Wraps a connected socket in an SSL context. This function effectively turns socket into an SSL socket. hostname should be specified so that the client knows which hostname the server certificate should be validated against.

This should be called on a connected socket, and will perform an SSL handshake immediately.

Disclaimer: This code is not well tested, may be very unsafe and prone to security vulnerabilities.

  Source Edit
proc getSocketError(socket: Socket): OSErrorCode {...}{.raises: [OSError], tags: [].}
Checks osLastError for a valid error. If it has been reset it uses the last error stored in the socket object.   Source Edit
proc socketError(socket: Socket; err: int = -1; async = false; lastError = -1.OSErrorCode): void {...}{.
    gcsafe, raises: [SslError, OSError], tags: [].}

Raises an OSError based on the error code returned by SSLGetError (for SSL sockets) and osLastError otherwise.

If async is true no error will be thrown in the case when the error was caused by no data being available to be read.

If err is not lower than 0 no exception will be raised.

  Source Edit
proc listen(socket: Socket; backlog = SOMAXCONN) {...}{.tags: [ReadIOEffect],
    raises: [OSError].}

Marks socket as accepting connections. Backlog specifies the maximum length of the queue of pending connections.

Raises an OSError error upon failure.

  Source Edit
proc bindAddr(socket: Socket; port = Port(0); address = "") {...}{.tags: [ReadIOEffect],
    raises: [ValueError, OSError].}

Binds address:port to the socket.

If address is "" then ADDR_ANY will be bound.

  Source Edit
proc acceptAddr(server: Socket; client: var owned(Socket); address: var string;
               flags = {SafeDisconn}) {...}{.tags: [ReadIOEffect], gcsafe, locks: 0,
                                     raises: [OSError, IOError, SslError].}

Blocks until a connection is being made from a client. When a connection is made sets client to the client socket and address to the address of the connecting client. This function will raise OSError if an error occurs.

The resulting client will inherit any properties of the server socket. For example: whether the socket is buffered or not.

The accept call may result in an error if the connecting socket disconnects during the duration of the accept. If the SafeDisconn flag is specified then this error will not be raised and instead accept will be called again.

  Source Edit
proc accept(server: Socket; client: var owned(Socket); flags = {SafeDisconn}) {...}{.
    tags: [ReadIOEffect], raises: [OSError, IOError, SslError].}

Equivalent to acceptAddr but doesn't return the address, only the socket.

The accept call may result in an error if the connecting socket disconnects during the duration of the accept. If the SafeDisconn flag is specified then this error will not be raised and instead accept will be called again.

  Source Edit
proc close(socket: Socket) {...}{.raises: [SslError, OSError], tags: [].}
Closes a socket.   Source Edit
proc toCInt(opt: SOBool): cint {...}{.raises: [], tags: [].}
Converts a SOBool into its Socket Option cint representation.   Source Edit
proc getSockOpt(socket: Socket; opt: SOBool; level = SOL_SOCKET): bool {...}{.
    tags: [ReadIOEffect], raises: [OSError].}
Retrieves option opt as a boolean value.   Source Edit
proc getLocalAddr(socket: Socket): (string, Port) {...}{.raises: [OSError, Exception],
    tags: [].}

Get the socket's local address and port number.

This is high-level interface for getsockname.

  Source Edit
proc getPeerAddr(socket: Socket): (string, Port) {...}{.raises: [OSError, Exception],
    tags: [].}

Get the socket's peer address and port number.

This is high-level interface for getpeername.

  Source Edit
proc setSockOpt(socket: Socket; opt: SOBool; value: bool; level = SOL_SOCKET) {...}{.
    tags: [WriteIOEffect], raises: [OSError].}
Sets option opt to a boolean value specified by value.
var socket = newSocket()
socket.setSockOpt(OptReusePort, true)
socket.setSockOpt(OptNoDelay, true, level=IPPROTO_TCP.toInt)
  Source Edit
proc connectUnix(socket: Socket; path: string) {...}{.raises: [], tags: [].}
Connects to Unix socket on path. This only works on Unix-style systems: Mac OS X, BSD and Linux   Source Edit
proc bindUnix(socket: Socket; path: string) {...}{.raises: [], tags: [].}
Binds Unix socket to path. This only works on Unix-style systems: Mac OS X, BSD and Linux   Source Edit
proc hasDataBuffered(s: Socket): bool {...}{.raises: [], tags: [].}
Determines whether a socket has data buffered.   Source Edit
proc recv(socket: Socket; data: pointer; size: int): int {...}{.tags: [ReadIOEffect],
    raises: [].}

Receives data from a socket.

Note: This is a low-level function, you may be interested in the higher level versions of this function which are also named recv.

  Source Edit
proc recv(socket: Socket; data: pointer; size: int; timeout: int): int {...}{.
    tags: [ReadIOEffect, TimeEffect], raises: [TimeoutError, OSError].}
overload with a timeout parameter in milliseconds.   Source Edit
proc recv(socket: Socket; data: var string; size: int; timeout = -1; flags = {SafeDisconn}): int {...}{.
    raises: [TimeoutError, OSError, SslError], tags: [ReadIOEffect, TimeEffect].}

Higher-level version of recv.

When 0 is returned the socket's connection has been closed.

This function will throw an OSError exception when an error occurs. A value lower than 0 is never returned.

A timeout may be specified in milliseconds, if enough data is not received within the time specified a TimeoutError exception will be raised.

Note: data must be initialised.

Warning: Only the SafeDisconn flag is currently supported.

  Source Edit
proc recv(socket: Socket; size: int; timeout = -1; flags = {SafeDisconn}): string {...}{.inline,
    raises: [TimeoutError, OSError, SslError], tags: [ReadIOEffect, TimeEffect].}

Higher-level version of recv which returns a string.

When "" is returned the socket's connection has been closed.

This function will throw an OSError exception when an error occurs.

A timeout may be specified in milliseconds, if enough data is not received within the time specified a TimeoutError exception will be raised.

Warning: Only the SafeDisconn flag is currently supported.

  Source Edit
proc readLine(socket: Socket; line: var TaintedString; timeout = -1;
             flags = {SafeDisconn}; maxLength = MaxLineLength) {...}{.
    tags: [ReadIOEffect, TimeEffect], raises: [TimeoutError, OSError, SslError].}

Reads a line of data from socket.

If a full line is read \r\L is not added to line, however if solely \r\L is read then line will be set to it.

If the socket is disconnected, line will be set to "".

An OSError exception will be raised in the case of a socket error.

A timeout can be specified in milliseconds, if data is not received within the specified time a TimeoutError exception will be raised.

The maxLength parameter determines the maximum amount of characters that can be read. The result is truncated after that.

Warning: Only the SafeDisconn flag is currently supported.

  Source Edit
proc recvLine(socket: Socket; timeout = -1; flags = {SafeDisconn};
             maxLength = MaxLineLength): TaintedString {...}{.
    raises: [TimeoutError, OSError, SslError], tags: [ReadIOEffect, TimeEffect].}

Reads a line of data from socket.

If a full line is read \r\L is not added to the result, however if solely \r\L is read then the result will be set to it.

If the socket is disconnected, the result will be set to "".

An OSError exception will be raised in the case of a socket error.

A timeout can be specified in milliseconds, if data is not received within the specified time a TimeoutError exception will be raised.

The maxLength parameter determines the maximum amount of characters that can be read. The result is truncated after that.

Warning: Only the SafeDisconn flag is currently supported.

  Source Edit
proc recvFrom(socket: Socket; data: var string; length: int; address: var string;
             port: var Port; flags = 0'i32): int {...}{.tags: [ReadIOEffect],
    raises: [Exception, OSError, IOError].}

Receives data from socket. This function should normally be used with connection-less sockets (UDP sockets).

If an error occurs an OSError exception will be raised. Otherwise the return value will be the length of data received.

Warning: This function does not yet have a buffered implementation, so when socket is buffered the non-buffered implementation will be used. Therefore if socket contains something in its buffer this function will make no effort to return it.

  Source Edit
proc skip(socket: Socket; size: int; timeout = -1) {...}{.raises: [TimeoutError, OSError],
    tags: [TimeEffect, ReadIOEffect].}

Skips size amount of bytes.

An optional timeout can be specified in milliseconds, if skipping the bytes takes longer than specified a TimeoutError exception will be raised.

Returns the number of skipped bytes.

  Source Edit
proc send(socket: Socket; data: pointer; size: int): int {...}{.tags: [WriteIOEffect],
    raises: [].}

Sends data to a socket.

Note: This is a low-level version of send. You likely should use the version below.

  Source Edit
proc send(socket: Socket; data: string; flags = {SafeDisconn}) {...}{.tags: [WriteIOEffect],
    raises: [SslError, OSError].}
sends data to a socket.   Source Edit
proc trySend(socket: Socket; data: string): bool {...}{.tags: [WriteIOEffect], raises: [].}
Safe alternative to send. Does not raise an OSError when an error occurs, and instead returns false on failure.   Source Edit
proc sendTo(socket: Socket; address: string; port: Port; data: pointer; size: int;
           af: Domain = AF_INET; flags = 0'i32) {...}{.tags: [WriteIOEffect],
    raises: [OSError].}

This proc sends data to the specified address, which may be an IP address or a hostname, if a hostname is specified this function will try each IP of that hostname.

If an error occurs an OSError exception will be raised.

Note: You may wish to use the high-level version of this function which is defined below.

Note: This proc is not available for SSL sockets.

  Source Edit
proc sendTo(socket: Socket; address: string; port: Port; data: string) {...}{.
    tags: [WriteIOEffect], raises: [OSError].}

This proc sends data to the specified address, which may be an IP address or a hostname, if a hostname is specified this function will try each IP of that hostname.

If an error occurs an OSError exception will be raised.

This is the high-level version of the above sendTo function.

  Source Edit
proc isSsl(socket: Socket): bool {...}{.raises: [], tags: [].}
Determines whether socket is a SSL socket.   Source Edit
proc getFd(socket: Socket): SocketHandle {...}{.raises: [], tags: [].}
Returns the socket's file descriptor   Source Edit
proc IPv4_any(): IpAddress {...}{.raises: [], tags: [].}
Returns the IPv4 any address, which can be used to listen on all available network adapters   Source Edit
proc IPv4_loopback(): IpAddress {...}{.raises: [], tags: [].}
Returns the IPv4 loopback address (127.0.0.1)   Source Edit
proc IPv4_broadcast(): IpAddress {...}{.raises: [], tags: [].}
Returns the IPv4 broadcast address (255.255.255.255)   Source Edit
proc IPv6_any(): IpAddress {...}{.raises: [], tags: [].}
Returns the IPv6 any address (::0), which can be used to listen on all available network adapters   Source Edit
proc IPv6_loopback(): IpAddress {...}{.raises: [], tags: [].}
Returns the IPv6 loopback address (::1)   Source Edit
proc `==`(lhs, rhs: IpAddress): bool {...}{.raises: [], tags: [].}
Compares two IpAddresses for Equality. Returns true if the addresses are equal   Source Edit
proc `$`(address: IpAddress): string {...}{.raises: [], tags: [].}
Converts an IpAddress into the textual representation   Source Edit
proc dial(address: string; port: Port; protocol = IPPROTO_TCP; buffered = true): owned(
    Socket) {...}{.tags: [ReadIOEffect, WriteIOEffect], raises: [OSError, IOError].}
Establishes connection to the specified address:port pair via the specified protocol. The procedure iterates through possible resolutions of the address until it succeeds, meaning that it seamlessly works with both IPv4 and IPv6. Returns Socket ready to send or receive data.   Source Edit
proc connect(socket: Socket; address: string; port = Port(0)) {...}{.tags: [ReadIOEffect],
    raises: [OSError, SslError].}

Connects socket to address:port. Address can be an IP address or a host name. If address is a host name, this function will try each IP of that host name. htons is already performed on port so you must not do it.

If socket is an SSL socket a handshake will be automatically performed.

  Source Edit
proc connect(socket: Socket; address: string; port = Port(0); timeout: int) {...}{.
    tags: [ReadIOEffect, WriteIOEffect], raises: [OSError, TimeoutError].}

Connects to server as specified by address on port specified by port.

The timeout paremeter specifies the time in milliseconds to allow for the connection to the server to be made.

  Source Edit
proc getPrimaryIPAddr(dest = parseIpAddress("8.8.8.8")): IpAddress {...}{.
    raises: [OSError, SslError, ValueError, Exception], tags: [ReadIOEffect].}

Finds the local IP address, usually assigned to eth0 on LAN or wlan0 on WiFi, used to reach an external address. Useful to run local services.

No traffic is sent.

Supports IPv4 and v6. Raises OSError if external networking is not set up.

echo $getPrimaryIPAddr()  # "192.168.1.2"
  Source Edit

Templates

template `&=`(socket: Socket; data: typed)
an alias for 'send'.   Source Edit

Exports

Port, $, $, $, $, $, $, $, $, $, $, $, $, $, $, $, $, $, $, $, $, $, $, $, $, $, $, $, $, $, $, ==, ==, ==, ==, ==, ==, ==, ==, ==, ==, ==, ==, ==, ==, ==, ==, ==, ==, ==, ==, ==, ==, ==, ==, ==, ==, ==, ==, ==, ==, ==, ==, ==, ==, ==, Domain, SockType, Protocol