slink(ADMN)

Syntax

Description

When the kernel is relinked, the /etc/kslgen script calls slink to parse the configuration files in the directory /etc/strcf.d (see strcf(SFF)). These files define the TCP/IP network interfaces known to the kernel. (The output is written to /etc/conf/pack.d/ksl/space.c.) The kernel must be relinked and rebooted for a new STREAMS configuration to take effect.

The following options may be specified on the slink command line:

-c file

Use file instead of /etc/strcf.

-f

Do not fork. slink must remain in the foreground, holding open its file descriptors. This assumes that persistent links are not being used. In this case, slink will only be able to build streams that are defined to use regular links (I_LINK; see streamio(M)).

-G

Generate C source code to be used by the ksl (kernel STREAMS linker) driver.

-n file

Write information about device nodes and external variables to file.

-u

Unlink persistent links (shut down the protocol stack). This option can only be run by the user root, and not by others with root authority.

-v

Verbose mode (each operation is logged to stderr).

The configuration file contains a list of functions, each of which is composed of a list of commands. Each command is a call to one of the functions defined in the configuration file or to one of a set of built-in functions. Among the built-in functions are the basic STREAMS operations open, link, plink, and push, along with several TCP/IP-specific functions.

A function definition has the following form:

   function-name {
   	command1
   	command2
   	...
   }

   function arg1 arg2 arg3 ...

   var = function arg1 arg2 arg3 ...

Comments are delimited by ``#'' and newline, and are considered equivalent to a newline.

Function and variable names may be any string of characters taken from A-Z, a-z, 0-9, and ``_'', except that the first character cannot be a digit. Function names and variable names occupy separate name spaces. All functions are global and may be forward referenced. All variables are local to the functions in which they occur.

Variables are defined when they appear to the left of an equals (=) on a command line. For example:

   tcp = open /dev/inet/tcp

Arguments to a command may be either variables, parameters, or strings.

A variable that appears as an argument must have been assigned a value on a previous command line in that function.

Parameters take the form of a dollar sign ($) followed by one or two decimal digits, and are replaced with the corresponding argument from the function call. If a given parameter was not specified in the function call, an error results (for example, if a command references $3 and only two arguments were passed to the function, an execution error will occur).

Strings are sequences of characters optionally enclosed in double quotes ("). Quotes may be used to prevent a string from being interpreted as a variable name or a parameter, and to allow the inclusion of spaces, tabs, and the special characters {, }, =, and #. The backslash (\) may also be used to quote the characters {, }, =, ", #, and \ individually.

The following built-in functions are provided by slink:

addmcaddr MAC_address

Send a message to the network driver to implement a multicast Media Access Control (MAC) address (MAC_address). The 48-bit address must be formatted as six hexadecimal numbers separated by colons, for example: 01:00:5e:7f:7f:7f.

call function

Call a function in the kernel. No arguments may be supplied and no return value is expected. For example, ip_set_if_address is called in /etc/strcf to set the IP addresses for the network and local loopback interfaces at boot time.

close fd

Close file descriptor fd.

dlattach fd unit

Send a DL_ATTACH_REQ message down the stream referenced by fd specifying unit unit.

dlbind fd sap

Send a DL_BIND_REQ message down the stream referenced by fd specifying the Service Access Point sap. The media-level address of the device at the bottom of the stream is returned if the operation succeeds. It can be used later as the argument to the sifaddr command.

dlsubsbind fd ssap

Send a DL_SUBS_BIND_REQ message down the stream referenced by fd specifying the Secondary Service Access Point ssap.

exit

Cause a kernel panic due to the failure of a built-in command in the streams-linking process.

initqp path qname lowat hiwat ...

Send an INITQPARMS (initialize queue parameters) ioctl to the driver corresponding to pathname path. qname specifies the queue for which the low and high water marks will be set, and must be one of:

hd

stream head

rq

read queue

wq

write queue

muxrq

multiplexor read queue

muxwq

multiplexor write queue

lowat and hiwat specify the new low and high water marks for the queue. Both lowat and hiwat must be present. To change only one of these parameters, the other may be replaced with a dash ``-''. Up to five qname lowat hiwat triplets may be present.

label label_name

Define a label named label_name.

link fd1 fd2

Link the stream referenced by fd2 beneath the stream referenced by fd1. Returns the link identifier associated with the link. Note that fd2 cannot be used after this operation.

noexit

Allow operations to continue rather than causing a kernel panic due to the failure of a built-in command in the streams-linking process. The currently executing function is terminated and execution resumes at the next statement.

onerror label_name

On error, jump to the label named label_name.

open path

Open the device specified by pathname path. Returns a file descriptor referencing the open stream.

plink fd1 fd2

Link the stream referenced by fd2 beneath the stream referenced by fd1 using a persistent link. Returns the link identifier associated with the link. Note that fd2 cannot be used after this operation.

push fd module

Push module onto the stream referenced by fd.

return val

Set the return value for the current function to val. Note that executing a return command does not terminate execution of the current function.

sifaddr fd name addr

Sends a SIOCSIFNAME ioctl down the stream referenced by fd. The arguments are an interface name and the media-level address associated with the specified name. This is used by the ARP driver to reply to ARP queries.

sifhrd fd type

Send a SIOCSHRDTYPE (set interface hardware type) ioctl down the stream referenced by fd. The hardware type is used by the ARP driver when sending messages. Legal values for type are ``ether'' and ``ieee''.

sifname fd link name flags

Send a SIOCSIFNAME (set interface name) ioctl down the stream referenced by fd for the link associated with link identifier link specifying the name name. flags are specified in hexadecimal by OR'ing the bit values defined in /usr/include/sys/net/if.h:

0x1

interface is up (IFF_UP)

0x2

broadcast address is valid (IFF_BROADCAST)

0x4

turn on debugging (IFF_DEBUG)

0x8

loopback through the network (IFF_LOOPBACK)

0x10

interface is a point-to-point link (IFF_POINTOPOINT)

0x20

interface wants to hear IP ioctl requests (IFF_WANTIOCTLS)

0x40

resources allocated (IFF_RUNNING)

0x80

no address resolution protocol (IFF_NOARP)

0x100

link-specific flag (IFF_LINK0)

0x200

receive all multicast packets (IFF_ALLMULTI; not implemented, reserved for future use)

0x400

link-specific flag (IFF_LINK1)

0x800

select one-packet mode (IFF_ONEPACKET)

0x1000

link-specific flag (IFF_LINK2)

0x2000

interface cannot hear own transmissions (IFF_SIMPLEX)

0x4000

interface supports IP multicasting (IFF_MULTICAST)

strcat str1 str2

Concatenate strings str1 and str2 and return the resulting string.

unitsel fd unit

Send a IF_UNITSEL (unit select) ioctl down the stream referenced by fd specifying unit unit.

Warning

Files

/etc/strcf

example STREAMS configuration file

/etc/strcf.d

directory containing STREAMS configuration files

See also