---
name: "ns_sock"
section: "3"
platform: "linux"
package: "aolserver4"
version: "4.0.10-7"
release: "Debian 4.0 (Etch)"
platforms: ["linux"]
url: "https://new.carta.tech/ns_sock"
---

# ns\_sock(3)

Network socket commands

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## NAME

ns\_sockaccept, ns\_sockblocking, ns\_sockcallback, ns\_sockcheck, ns\_socketpair, ns\_socklisten, ns\_socklistencallback, ns\_socknonblocking, ns\_socknread, ns\_sockopen, ns\_sockselect - Network socket commands

## SYNOPSIS

**ns\_sockaccept** *sockid*

**ns\_sockblocking** *sockid*

**ns\_sockcallback** *sockid script when*

**ns\_sockcheck** *fileid*

**ns\_socketpair**

**ns\_socklisten** *address port*

**ns\_socklistencallback** *address port script*

**ns\_socknonblocking** *sockid*

**ns\_socknread** *sockid*

**ns\_sockopen** ?*-nonblock* \| *-timeout seconds*? *host port*

**ns\_sockselect** ?*-timeout seconds*? *rfds wfds efds*

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```

## DESCRIPTION

Performs one of several network socket operations, providing a means to  manipulate and use sockets directly within AOLserver.

- **ns\_sockaccept** *sockid*

  Accepts a new connection on the socket specified by *sockid* and returns a list containing the read and write file descriptors for the socket, respectively.

  The file descriptors can be used with Tcl's **puts**, **gets**, **read** or any other Tcl socket manipulation commands.

  **ns\_sockaccept** does not create a socket for you. It is normally used in conjunction with **ns\_sockcallback**, **ns\_socklisten**, and **ns\_socklistencallback**.

  You can use **ns\_sockcheck** to see if the socket is valid before using **ns\_sockaccept** on it.

- **ns\_sockblocking** *sockid*

  Sets the socket specified by *sockid* to blocking mode. In blocking mode, an operation on a socket must complete before the command can return. This can cause your process or thread to block forever if the operation does not complete. If that happens in an ADP, the page may never complete until the socket is interrupted, closed or a TCP timeout occurs.

- **ns\_sockcallback** *sockid script when*

  Registers a socket callback script that will be run when a connection is made to the socket specified by *sockid*.

  The socket must already exist. You can create a socket using **ns\_socklisten**.

  The *script* should accept *sockid* and *when* as its first two arguments.

  The *script* is responsible for doing an **ns\_sockaccept** on *sockid* prior to reading from and writing to the socket.

  If the same *script* will handle all *when* values, you must still register the script four separate times, once for each type of *when* value.

  The *when* value is passed to *script* when *script* is invoked. The *when* value is one of:

-

  *r* - the socket is readable

-

  *w* - the socket is writeable

-

  *e* - the socket has an exceptional condition

-

  *x* - the server is shutting down

- **ns\_sockcheck** *fileid*

  Uses recv() or send() calls to check if a socket is still connected. The *fileid* is the read or write file id returned by **ns\_sockopen**.

  This function is useful if you used the *-nonblock* option with **ns\_sockopen** after calling **ns\_sockselect**.

- **ns\_socketpair**

  Creates a pair of connected sockets and returns a list of file ids: the first one for reads and the second one for writes.

- **ns\_socklisten** *address port*

  Creates a new socket and listens for connections at the specified *address* and *port*. An asterisk (\*) can be used as the *address* argument to specify all addresses.

  The socket id is returned.

  You must use **ns\_sockaccept** to accept connections on the socket.

- **ns\_socklistencallback** *address port script*

  Creates a new socket and listens for connections at the specified *address* and *port*. An asterisk (\*) can be used as the *address* argument to specify all addresses.

  Runs *script* when a new connection is received. The *script* must use **ns\_sockaccept** on the

- **ns\_socknonblocking** *sockid*

  Sets the socket specified by *sockid* to nonblocking.

- **ns\_socknread** *sockid*

  Returns the number of bytes waiting to be read from the socket specified by *sockid*.

- **ns\_sockopen** ?*-nonblock* \| *-timeout seconds*? *host port*

  Uses the socket(), bind() and connect() calls to connect to the remote *host* on the specified *port*. **ns\_sockopen** returns a list containing the read and write fileids, respectively.

  The *-nonblock* option causes **ns\_sockopen** to return immediately, while the connect is still in progress by the operating system. Use **ns\_sockcheck** with the write fileid to see if the connect has completed before attempting to read from or write to the socket.

  The *-timeout* option specifies how long to wait for the connect to  be made in *seconds* before timing out.

- **ns\_sockselect** ?*-timeout seconds*? *rfds wfds efds*

  Uses a call to select() to determine which fileids are readable, writable or have exceptional conditions. **ns\_sockselect** returns a list of three lists: readable fileids, writable fileids, and the fileids with exceptions.

  The *-timeout* option specifies how many *seconds* to wait  for **ns\_sockselect** before timing out.

  The *rfds*, *wfds* and *efds* arguments are lists of readable fileids, writeable fileids, and fileids with exceptions, respectively.

Be careful using these socket commands in an ADP or a procedure called by an ADP. If a socket command hangs, the page may not finish being served to the user until the TCP connection times out, typically several minutes later.

## SEE ALSO

nsd(1), [info(n)](/info/n.md)

## KEYWORDS